No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
High-resolution sulphur isotope analysis of speleothem carbonate by secondary ionisation mass spectrometry
Abstract
Sulphur emitted into the atmosphere from industrial activity is regarded as a key mechanism in forcing recent climate and has impacts upon the environment and human health at both local and regional scales. Trace amounts of sulphate present within speleothem carbonate can be used to provide an emissions inventory for regional sulphur loading to the atmosphere where sulphur isotopes can be extracted and used as a tool for provenance. However, speleothem sulphur concentrations are low and manual techniques for sulphur isotope analysis allow only low sampling resolution. SIMS (Secondary Ionisation Mass Spectrometry) is used here to develop records of sulphur isotopic change in speleothems from the Italian and Austrian Alps, where annual laminae are less than 100 µm thick. Analysis at annual resolution over the past 100 years demonstrates an excursion in sulphur isotopic composition from values close to the carbonate bedrock end-member composition in the pre-industrial era, to values isotopically depleted in 34 S. This trend is mirrored by increasing concentrations of sulphate and is suggested to reflect the increase in SO2 emissions with industrial activity. Subsequent decline in speleothem sulphate concentrations in one of the stalagmites reflects the recent European decline in industrial atmospheric SO2 content and is matched by a rebound in sulphur isotopic composition to values more enriched in 34 S. Superimposed on this general secular trend are smaller (annual) variations in concentration reflecting cave environmental conditions. High magnitude events of short duration, potentially reflect volcanic inputs of SO2 or the incorporation of dust particulates into the speleothem carbonate. This is the first micro-analysis of carbonate-associated sulphate (CAS) sulphur isotopes by SIMS. SIMS analysis of δ34S–SO4 in speleothem carbonate reveals a high resolution archive depicting a regional sulphur emissions inventory for SO2 loading to the atmosphere.
... In this regard, Grotta di Ernesto is an excellent site because it is largely undisturbed and contains numerous active annually laminated stalagmites (Frisia et al., 2003). Moreover, it is one of the most extensively monitored cave sites worldwide where detailed hydrochemical monitoring, which has been carried out since 1993, established the relationships between speleothem proxy data and climate and environmental parameters (Borsato, 1995;Borsato et al., 2007;Borsato, 1997;Borsato et al., 2015aBorsato et al., , 2015bBorsato et al., , 2016Fairchild et al., 2000Fairchild et al., , 2001Frisia and Borsato, 2010;Frisia et al., 2000Frisia et al., , 2003Frisia et al., , 2005Frisia et al., , 2008Frisia et al., , 2011Huang et al., 2001;Johnston et al., 2013;McDermott et al., 1999;Miorandi et al., 2010;Scholz et al., 2012;Smith et al., 2006Smith et al., , 2009Wynn et al., 2010Wynn et al., , 2013Wynn et al., , 2014bWynn et al., , 2018. ...
... In the last two decades, cave monitoring also included the analysis of colloidal transport in dripwater (Hartland et al., 2012), as well as sulfate concentrations and sulfate isotopes in both drips and stalagmites, aimed at establishing a speleothem archive of atmospheric sulfur composition (Borsato et al., 2015b;Fairchild and Frisia, 2014;Fairchild et al., 2009;Frisia et al., 2005Frisia et al., , 2008Wynn et al., 2010Wynn et al., , 2013Wynn et al., , 2014b. Soil carbon dynamics were investigated by analyzing the 14 C activity and δ 13 C values of C dissolved in soil and cave drip water (Frisia et al., 2011). ...
... Sulfur isotope analyses of speleothem carbonate were undertaken using polished, gold-coated thin sections 150 μm thick using a Cameca 1270 ion probe at the University of Edinburgh, School of Geosciences. 34 S/ 32 S ratios are expressed using the delta convention in per mil notation standardised to VCDT (Wynn et al., 2010). ...
Annually laminated stalagmites ER77 and ER78 from Grotta di Ernesto provide an accurate annual record of environmental and anthropogenic signals for the last ~200 years. Two major transitions are recorded in the stalagmites. The first coincides with the year 1840 CE, when a change from porous and impurity-rich-laminae to clean, translucent laminae occurs. This is accompanied by a steady increase in the growth rate, a decrease in fluorescence and a sharp increase in δ ¹³ C values. These changes concur with the end of the Little Ice Age. The second transition takes place around the year 1960 CE and corresponds with an increase in both annual growth rate and sulfur concentration in stalagmite ER78 at 4.2 mm from the top, and with the deflection point in the ¹⁴ C activity curve in stalagmite ER77 at 4.8 mm from the top. This latter is the stratigraphic signal proposed as the primary guide for the definition of the Anthropocene series. The following shift toward depleted δ ³⁴ S–SO 4 in stalagmite ER78 suggests that industrial pollution is a major source of sulfur. The interpretation of atmospheric signals (S, δ34 S, ¹⁴ C) in the stalagmites is affected by attenuation and time lags and the environmental signals are influenced by soil and ecosystem processes, while other anthropogenic signals (δ ¹⁵ N, ²³⁹ Pu) are not recorded. For these reasons, the stalagmite record is here proposed as an auxiliary (reference) section rather than a global standard. In summary, Grotta di Ernesto contains one of the best stalagmite records documenting the Anthropocene, and one of only two stalagmite records where the S peak has been measured at high resolution.
... atmospheric sulfur is assimilated by plants and algae, through which it is then passed onto aquatic and terrestrial consumers). Understanding changes in the loading and provenance of sulfur dioxide in the atmosphere could provide critical information regarding the efficacy of legislation and mitigation measures (Wynn et al. 2010, Barros et al. 2015. Furthermore, structurally substituted sulfate in biogenic carbonates can provide an accurate re cord of the sulfur isotope composition of ancient oceans, helping to uncover global environmental change over geological time scales (Kampschulte & Strauss 2004, Perrin et al. 2017. ...
... Standards with a known isotopic value can be developed from relevant biominerals, if material with homogenous sulfur isotope distributions can be found (e.g. coral standard used for speleothem carbonate; Wynn et al. 2010), or be synthetically produced (e.g. Weber et al. 2002). ...
... Provenance and loading of SO 2 emissions Natural and anthropogenic sources of atmospheric sulfur tracked using lichen thalli (Barros et al. 2015) and speleothem carbonate (Wynn et al. 2010). ...
Sulfur isotope ratios are used to untangle food web dynamics, track animal movements and determine dietary provenance. Yet, their application in the biomineralised tissues of animals is relatively unexplored. These tissues are particularly useful for isotopic analyses as they can retain a permanent and temporally-resolved chemical record over the lifetime of the organism. We experimentally determined whether biogenic carbonate records environmental variation in sulfur isotope ratios (34S/32S) in an aquatic system and whether such variation is influenced by the ambient water or diet. Juvenile fish were raised in two water treatments with differing sulfur isotope ratios, as well as three diet treatments with differing ratios. We subsequently analysed the calcium carbonate fish ear bones (otoliths) using secondary ion mass spectrometry, a technique that allowed the experimental growth of the otolith to be targeted. Our findings suggest that biogenic carbonate records variation in sulfur isotope ratios and that diet is not the sole source of sulfur isotope variation in aquatic consumers. Drawing from a multi-disciplinary body of literature we also reviewed the potential ecological and environmental applications of sulfur isotope analysis in biominerals. We emphasise the extensive application of sulfur isotope ratios and that progressing this field of research to include biominerals is a worthwhile pursuit.
... The sulphate content of speleothem carbonate has recently become appreciated as a valuable record of the changing sulphur biogeochemical cycle at a local to regional scale. Where atmospheric sulphur is deposited through precipitation, and cycling of sulphur through the biomass above the cave can be accounted for, secular trends in speleothem sulphur content can record regional pollution characteristics (Frisia et al., 2005;Wynn et al., 2008Wynn et al., , 2010Uchida et al., 2013), as well as infer volcanic events (Frisia et al., 2008;Badertscher et al., 2014) and periods of biomass burning (Nagra et al., 2016;Treble et al., 2016). However, beyond the long-term trends in speleothem sulphur content, there is much information still to be revealed by addressing sulphur dynamics at the sub-annual scale. ...
... We also use two different sulphate concentrations covering the range typically found in cave drip waters. Experimental results are compared to two European Alpine caves: Obir Cave (Spötl et al., 2005;Fairchild et al., 2010), Austria; and Grotta di Ernesto (Frisia et al., 2005;Borsato et al., 2007;Wynn et al., 2010Wynn et al., , 2013, Italy, where sample analysis at high temporal resolution demonstrates the seasonality of sulphate partitioning between cave waters and speleothem calcite. Summary data from other globally-distributed cave sites also allow calculation of partition co-efficients between sulphur contained in drip waters and speleothem calcite, albeit at a lower temporal resolution. ...
... The internal cave temperature is +6.7 +/-0.1 °C (Miorandi et al., 2010), and a strong seasonality in external temperature drives a cave ventilation pattern which holds a dominant influence over the cave carbon budget and speleothem growth patterns (Frisia et al., 2011). Speleothem ER78 was collected in 2000 and has been studied extensively for its sulphur content (Frisia et al., 2005;Wynn et al., 2010) and associated biogeochemical cycling of sulphur through the cave and overlying ecosystem (Wynn et al., 2013;Borsato et al., 2015). ...
Carbonate-associated sulphate (CAS) is a useful carrier of palaeoenvironmental information throughout the geologic record, particularly through its stable isotope composition. However, a paucity of experimental data restricts quantitative understanding of sulphate incorporation into carbonates, and consequently CAS concentrations and their diagenetic modifications are rarely interpreted. However, in the case of calcite speleothems, the remarkably high-resolution CAS records which are obtainable via modern microanalytical techniques represent a potentially invaluable source of palaeoenvironmental information. Here, we describe the results of controlled experiments of sulphate co-precipitation with calcite in freshwater solutions where pH, saturation state, and sulphate concentration were varied independently of each other. Solution pH is confirmed as the principal control on sulphate incorporation into calcite. The relative efficiency of incorporation was calculated as a partition coefficient DSO4 = (mSO4/mCO3)solid/(mSO4/mCO3)solution. High crystal growth rates (driven by either pH or saturation state) encouraged higher values of DSO4 because of an increasing concentration of defect sites on crystal surfaces. At low growth rates, DSO4 was reduced due to an inferred competition between sulphate and bicarbonate at the calcite surface. These experimental results are applied to understand the incorporation of sulphate into speleothem calcite. The experimentally determined pH-dependence suggests that strong seasonal variations in cave air PCO2 could account for annual cycles in sulphate concentration observed in stalagmites. Our new experimentally determined values of DSO4 were compared with DSO4 values calculated from speleothem-drip water monitoring from two caves within the Austrian and Italian Alps. At Obir cave, Austria, DSO4 (×10⁵) varies between 11.1 (winter) and 9.0 (summer) and the corresponding figures for Ernesto cave, Italy, are 15.4 (winter) and 14.9 (summer). These values approximate predicted DSO4 values based on our chamber experiments containing both low (2 ppm) and high (20 ppm) sulphate concentrations. Our experimental values of DSO4 obtained at crystal growth rates typical of stalagmites, closely match those observed in other cave sites from around the world. This validates the universality of the controls behind DSO4 and will enhance the use of speleothem CAS as a palaeoenvironmental proxy.
... The 18 th -and 19 th -century spikes in sulphate are signals of volcanic eruptions. (Frisia et al. 2003); b) 18 O and 13 C profiles (Scholz et al. 2012); c) Radiocarbon profile and comparable European atmospheric emissions (Fohlmeister et al. 2011); d) S concentration and δ 34 S (Frisia et al. 2005, Wynn et al. 2010. and two-tailed 95% bootstrap confidence intervals (blue) (from Esper et al. 2002); b) δ 13 C variability from Loader et al. (2013) for the period 1500-2008 CE measured in tree-ring cellulose for a composite tree-ring stable isotope chronology developed using Pinus sylvestris trees from northern Fennoscandia. ...
... Fairchild et al. 2009) and speleothems (e.g. Frisia et al. 2005, Wynn et al. 2010 during the second half of the 20 th century. ...
... The 14 C bomb-spike has been recorded from the cave (Figure 29c), but with a decade lag compared with atmospheric signals (Fohlmeister et al. 2011). Records of sulphur loading and lowering of δ 34 S in both speleothem and tree rings show a similar lag in the speleothems of about 15-20 years (Figure 29c), such that in 2000 CE the speleothem was still recording peak atmospheric loading (Wynn et al. 2010 that was locally experienced in the 1980s ...
The Anthropocene as a potential new unit of the International Chronostratigraphic Chart (which serves as the basis of the Geological Time Scale) is assessed in terms of the stratigraphic markers and approximate boundary levels available to define the base of the unit. The task of assessing and selecting potential Global Boundary Stratotype Section and Point (GSSP) candidate sections, a required part of the process in seeking formalisation of the term, is now being actively pursued. Here, we review the suitability of different stratified palaeoenvironmental settings and facies as potential hosts for a candidate GSSP and auxiliary sections, and the relevant stratigraphical markers for correlation. Published examples are evaluated for their strengths and weaknesses in this respect. A marked upturn in abundance of radioisotopes of 239Pu or 14C, approximately in 1952 and 1954 CE respectively, broadly coincident with a downturn in δ13C values, is applicable across most environments. Principal palaeoenvironments examined include: settings associated with accumulations of anthropogenic material, marine anoxic basins, coral reefs, estuaries and deltas, lakes at various latitudes, peat bogs, snow/ice layers, speleothems and trees. Together, many of these geographically diverse palaeoenvironments offer annual/subannual laminae that can be counted and independently dated radiometrically (e.g. by 210Pb). Examples of possible sections offer the possibility of correlation with annual/seasonal resolution. From among such examples, a small number of potentially representative sites require the acquisition of more systematic and comprehensive datasets, with correlation established between sections, to allow selection of a candidate GSSP and auxiliary stratotypes. The assessments in this paper will help find the optimal locations for these sections. (online first 30 Dec 2017; printed vers. March 2018)
... [9,20] Sulfur inputs from atmospheric pollution, volcanic and marine emissions have distinct end-member compositions. This allows identification of trends in anthropogenic pollution, [21] potentially high-resolution volcanic emission inventories [22] and records of atmospheric circulation dynamics. However, capture of these end-member signals is dependent upon the degree of modification in the soil and epikarst. ...
... A decrease in d 34 S for this speleothem confirms the origin of elevated S levels to be from industrial SO 2 emissions. [21] Offsets between the timing of changes to S emissions and isotopic values were attributed to changing isotopic signatures of pollution. [21] The peak SO 4 2À concentration in the speleothem calcite lags compared to the peak S emissions to the atmosphere, evident both here and in an analogous cave site at Ernesto, north-east Italy. ...
... [21] Offsets between the timing of changes to S emissions and isotopic values were attributed to changing isotopic signatures of pollution. [21] The peak SO 4 2À concentration in the speleothem calcite lags compared to the peak S emissions to the atmosphere, evident both here and in an analogous cave site at Ernesto, north-east Italy. This attenuation in SO 4 2À can be explained by the delayed recovery of the soil ecosystem as a result of storage of S in the biogeochemical cycle. ...
Speleothems (mineral deposits that formed in caves) are currently giving us some of the most exciting insights into environments and climates during the Pleistocene ice ages and the subsequent Holocene rise of civilizations. The book applies system science to Quaternary environments in a new and rigorous way and gives holistic explanations the relations between the properties of speleothems and the climatic and cave setting in which they are found. It is designed as the ideal companion to someone embarking on speleothem research and, since the underlying science is very broad, it will also be invaluable to a wide variety of others. Students and professional scientists interested in carbonate rocks, karst hydrogeology, climatology, aqueous geochemistry, carbonate geochemistry and the calibration of climatic proxies will find up-to-date reviews of these topics here. The book will also be valuable to Quaternary scientists who, up to now, have lacked a thorough overview of these important archives. Additional resources for this book can be found at: www.wiley.com/go/fairchild/speleothem.
... Stalagmites are known to record atmospheric sulphur loads and ecosystem dynamics in karst regions, thus expanding the inventory of trace element proxies extracted from speleothems to a level commensurate with ice cores (Frisia et al., 2005Wynn et al., 2008Wynn et al., , 2010Wynn et al., , 2013. Sulphur concentration trends in stalagmites were related to anthropogenic emissions starting in the late 19th century (Frisia et al., 2005Uchida et al., 2013). ...
... In this case, preferential flow routing through epikarst results in speleothem capture of a sulphate signal largely unmodified with respect to the atmospheric source. Most commonly, the biogeochemical cycling of sulphur through vegetation and soils and the successive mixing with stored soil and aquifer sources will delay, concentrate and fractionate the S chemical or isotopic signal in dripwater and, eventually, speleothems (Wynn et al., 2008(Wynn et al., , 2010(Wynn et al., , 2013. ...
... Despite the importance of understanding the timing of atmospheric sulphur transfer into caves, there are very few sulphur data available for karst dripwater (Wynn et al., 2008(Wynn et al., , 2010Riechelmann et al., 2011;Tremaine and Froelich, 2013;Uchida et al., 2013). Moreover, several data are strongly modified by evapotranspiration (Tremaine and Froelich, 2013) and pyrite oxidation in the host rock (Riechelmann et al., 2011), or were collected in caves located near the sea and affected by a high proportion of sea-salt derived SO 4 (Uchida et al., 2013). ...
... [9,20] Sulfur inputs from atmospheric pollution, volcanic and marine emissions have distinct end-member compositions. This allows identification of trends in anthropogenic pollution, [21] potentially high-resolution volcanic emission inventories [22] and records of atmospheric circulation dynamics. However, capture of these end-member signals is dependent upon the degree of modification in the soil and epikarst. ...
... A decrease in d 34 S for this speleothem confirms the origin of elevated S levels to be from industrial SO 2 emissions. [21] Offsets between the timing of changes to S emissions and isotopic values were attributed to changing isotopic signatures of pollution. [21] The peak SO 4 2À concentration in the speleothem calcite lags compared to the peak S emissions to the atmosphere, evident both here and in an analogous cave site at Ernesto, north-east Italy. ...
... [21] Offsets between the timing of changes to S emissions and isotopic values were attributed to changing isotopic signatures of pollution. [21] The peak SO 4 2À concentration in the speleothem calcite lags compared to the peak S emissions to the atmosphere, evident both here and in an analogous cave site at Ernesto, north-east Italy. This attenuation in SO 4 2À can be explained by the delayed recovery of the soil ecosystem as a result of storage of S in the biogeochemical cycle. ...
Synchrotron micro-X-ray fluorescence (mXRF) spectrometry is used to reveal trace element patterns within speleothem calcite at the sub-annual scale and provide one of the first calibrations to prevailing meteorological conditions. Mapping of Zn and SO42- within speleothem calcite was performed at the European Synchrotron Radiation Facility over three annual cycles (1977-1979). Peaks in mXRF Zn concentrations occur on an annual basis, although banding of lower XRF intensity reveals multiple events at the sub-annual scale. The delivery of Zn to the speleothem was found to be dependent upon the presence of a water excess, the condition of any overlying snowpack and the pH of the soil solution as controlled by microbial activity. This generated a pattern of Zn event laminae that documented increasing concentrations from winter through to the following autumn and complies with existing models inferring surface-active trace metals are delivered to the point of speleothem growth in association with natural organic matter (referred to as NOM-metal complexes). Minimum and maximum concentrations of speleothem SO42- coincide with winter and summer respectively, in contrast to the near constant SO42- concentrations of the drip water. Fluctuations in speleothem SO42- levels closely follow changes in cave external temperatures, thereby validating existing models of sulfate incorporation into carbonate minerals thought to be driven by cave ventilation dynamics and internal cave atmospheric pCO(2) (partial pressure). At the current resolution of analysis, this represents some of the first evidence linking event-based meteorological (temperature and precipitation) records to the trace element content of speleothem calcite, building towards reconstruction of indices of climatic change beyond the instrumental period.
... This highlights the potential for tree ring archives of sulphur isotopes to be used as a readily available, sensitive record of local atmospheric change if methods can be improved to enhance spatial resolution of analysis, optimise analytical precision, and increase sample throughput. Grotta di Ernesto is a shallow cave site developed within the dolomitized Jurassic limestone in which extensive in-situ monitoring of cave atmosphere (Frisia et al., 2011), hydrology (Miorandi et al., 2010), and drip water and speleothem geochemistry (Borsato, 1997(Borsato, , 2007Fairchild et al., 2000;Frisia et al., 2003Frisia et al., , 2008Hartland et al., 2012;Huang et al., 2001;Wynn et al., 2008Wynn et al., , 2010Wynn et al., , 2013, make this an ideal site to compare cave speleothem records of twentieth century environmental change with terrestrial records from tree ring dendrochemistry. Soils in the area are up to 1 m thick (calcareous brown forest soils; Rendzic Leptosol, pH 6.5e7.7) and overlie Jurassic dolomitized limestones with blocks of red marly limestones. ...
... Vegetation growth is well managed and dominated by deforestation events in the 19th and 20th centuries, thereby limiting longevity of available tree ring records. Sulphur pollution at the site has been documented in Wynn et al. (2010) and attributed to industrial activity within the nearby Valsugana valley, transported up to 4000 m altitude by strong vertical air mixing (Gabrielli et al., 2006). The sulphur biogeochemical cycle, traced from precipitation input to speleothem host, has been described within Wynn et al. (2013). ...
... multiple tree cores, ice cores, speleothems), but real merit in understanding environmental processes is afforded through consideration of different archives, which develop at the same location. Records of sulphur concentration and isotopic change within both speleothems (ER78) and trees (Abies 2) are depicted in Fig. 3. Sulphur isotopes within speleothem calcite, extracted from Grotta di Ernesto within the locale of tree sampling, were analysed by secondary ionization mass spectrometry and presented within Wynn et al. (2010). The controls on speleothem sulphur composition were found to be determined not only by atmospheric input, but also by biogeochemical cycling through vegetation, soils and groundwaters (Wynn et al., 2013). ...
Palaeorecords which depict changes in sulphur dynamics form an invaluable resource for recording atmospheric pollution. Tree rings constitute an archive that are ubiquitously available and can be absolutely dated, providing the potential to explore local- to regional-scale trends in sulphur availability. Rapid isotopic analysis by a novel "on-line" method using elemental analyser isotope ratio mass spectrometry (EA-IRMS) is developed, achieving sample precision of <0.4‰ using sample sizes of 40 mg wood powder. Tree cores from NE Italy show trends in pollution, evidenced through increasing concentrations of sulphur towards the youngest growth, and inverse trends in sulphur isotopes differentiating modern growth with light sulphur isotopes (+0.7‰) from pre-industrial growth (+7.5‰) influenced by bedrock composition. Comparison with speleothem records from the same location demonstrate replication, albeit offset in isotopic value due to groundwater storage. Using EA-IRMS, tree ring archives form a valuable resource for understanding local- to regional-scale sulphur pollution dynamics.
... Figure EC1. Thin section image in transmitted and fluorescent light (470 nm) of the topmost section of stalagmite ER78, which was collected in 2000, compared with the annual growth rate and age model derived from layer counting (Frisia et al., 2003), the fluorescence signal , the SO4-S concentration (Frisia et al., 2005), and δ 34 S-SO4 (Wynn et al., 2010). The proposed base of the Crawfordian stage at 1952 CE is highlighted together with four other time markers: (1) The passage from porous microcrystalline to compact columnar calcite associated with onset of faster growth at 8.6 mm dft (lamina age 1836 ± 15 CE); (2) the increase in the annual growth rate and S concentration (lamina age 1960 ± 2 CE); (3) a shift towards depleted δ 34 S-SO4 (lamina age 1975 ± 2 CE) that demonstrates an additional source of stalagmite sulfur originating from industrial pollution (Wynn et al., 2010); (4) the sudden increase of growth rate along a thin micro-detrital layer that corresponds to the opening of the cave entrance in autumn 1983 followed by archaeological excavations during summer 1984 (Dalmeri, 1985) and re-sealing the entrance in autumn 1984. ...
... Thin section image in transmitted and fluorescent light (470 nm) of the topmost section of stalagmite ER78, which was collected in 2000, compared with the annual growth rate and age model derived from layer counting (Frisia et al., 2003), the fluorescence signal , the SO4-S concentration (Frisia et al., 2005), and δ 34 S-SO4 (Wynn et al., 2010). The proposed base of the Crawfordian stage at 1952 CE is highlighted together with four other time markers: (1) The passage from porous microcrystalline to compact columnar calcite associated with onset of faster growth at 8.6 mm dft (lamina age 1836 ± 15 CE); (2) the increase in the annual growth rate and S concentration (lamina age 1960 ± 2 CE); (3) a shift towards depleted δ 34 S-SO4 (lamina age 1975 ± 2 CE) that demonstrates an additional source of stalagmite sulfur originating from industrial pollution (Wynn et al., 2010); (4) the sudden increase of growth rate along a thin micro-detrital layer that corresponds to the opening of the cave entrance in autumn 1983 followed by archaeological excavations during summer 1984 (Dalmeri, 1985) and re-sealing the entrance in autumn 1984. Note the inverted scale for δ 34 S. ...
This part of the Anthropocene Working Group (AWG) submission proposes that the base of the Anthropocene should be defined as series/epoch, terminating the Holocene Series/Epoch with a single Crawfordian stage/age using a Global boundary Stratotype Section and Point (GSSP) in an annually varved Crawford Lake core, Ontario, Canada, defined at 17.5 cm in core CRA23-BC-1F-B at the base of the dark lamina in a varve deposited in 1952 CE, at the level where the primary marker shows a rapid increase in 239+240Pu concentrations (coinciding with a globally recognisable, isochronous signal of the first above-ground thermonuclear tests). Secondary markers, determined in precisely correlated core closely adjacent to the proposed GSSP host, include a marked increase in 14C values and in spheroidal carbonaceous particles (SCPs), increased heavy metal concentrations, a decline in δ15N values, a marked change in phytoplankton assemblages and declines in elm (Ulmus) pollen and in non-arboreal pollen. The submission also provides descriptions of three proposed Standard Auxiliary Boundary Stratotypes (SABSs), in cores extracted from marine anoxic sediments of Beppu Bay (Japan), in Sihailongwan Maar Lake (China) and in the Śnieżka Peatland (Poland) and eight reference sections located in cores extracted from marine anoxic sediments in the Baltic Sea, from coral bioherms off Australia and in the Gulf of Mexico, from an Antarctic ice core, from San Francisco Estuary and nearby lake (USA), in a speleothem from northern Italy and a section in urban anthropogenic deposits in Austria. This ubiquity of signals verifies that the Anthropocene can be widely delineated as a sharply distinctive chronostratigraphic unit in diverse terrestrial and marine depositional environments, and reflects a major Earth System change that will have geologically lasting consequences.
... A follow-up paper will be then devoted to describe the internal structure of annual laminated stalagmites by comparying S-μXRF mapping with optical and fluorescent microscopy. In the last decades the demand for annual to sub-annual climate proxy records expanded the use of high-resolution analytical techniques including laser-induced breakdown spectroscopy (LIBS) [44], secondary ionization mass spectrometry (SIMS) [17,18,22,[45][46][47][48], nuclear microprobe particle-induced X-ray fluorescence (PIXE), Rutherford backscattering spectrometry (RBS) [39,49], and full field X-ray fluorescence (FF-XRF) [50,51]. However, most of these techniques are limited by either sample size, spatial resolution, or detection limits for elements at ppm levels, all crucial aspects in speleothem-based research. ...
... However, most of these techniques are limited by either sample size, spatial resolution, or detection limits for elements at ppm levels, all crucial aspects in speleothem-based research. For these reasons, they have been utilised in pilot studies as well as for the investigation of short-lived climate and environmental events [17,18,48], while S-μXRF and LA-ICP-MS are emerging as the two most used techniques for speleothem mapping [19,32,33]. In particular, with respect to S-μXRF, speleothem mapping by LA-ICP-MS (in rasterscanning mode) can detect a larger suite of elements with lower detection limits [52], but it is limited to a resolution of around 20 μm [19]. ...
Annually laminated stalagmites are an exceptional archive of high-resolution past hydroclimate changes and provide robust annually-resolved age models. Stalagmite chemical annual laminae are invisible through optical and fluorescence microscopy, but are revealed by X-ray fluorescence or mass-spectrometry techniques. Synchrotron radiation based micro-X-ray fluorescence (S-μXRF) has the unique advantage of creating 2-dimensional maps of element distribution, which allows visualizing lateral heterogeneity and porosity that pose problems when one dimensional line-scanning techniques, such as LA-ICP-MS, are used. Here, we show how S-μXRF fast element mapping allows obtaining robust age models and palaeoclimate data from stalagmites otherwise difficult to date. Analytical challenges and solution to problems are discussed for both thick polished slabs and thin sections. The elements detectable through the fast acquisition mode (dwell time 1 to 4 ms) are typically Ca, Sr, Br, while Fe, Zn, Ni, Cu, Mn, Y, and Rb are occasionally detected in few distinctive layers or, in association with grain inclusions and porosity. Only Sr, however, exhibits a consistent and clear annual cyclicity. At incident angles of 90° the attenuation depth for Sr is ca. 240 μm and, therefore thick samples are preferable as they produce stronger fluorescence signal and sharper images unaffected by non-linear drift. On the other hand, thick samples are more affected by geometric and edge effects that can be particularly severe in the presence of irregular lamination and when the laminae are dipping with variable angle within the sample. The Sr concentration in the tropical stalagmites analysed in this study varied from 15 to 600 ppm, which strongly influences the dwell time needed to obtain high-quality maps. For Sr concentration below 20 ppm the ideal dwell time exceeds 20 ms and this renders the acquisition of large maps (> 20 Megapixels) hardly feasible. For concentrations above 20 ppm the fast mapping (dwell time < 5 ms) through S-μXRF is by far the best methodology to visualise chemical annual cycles in stalagmites.
... SIMS stable isotope studies have investigated the δ 18 O, δ 13 C and δ 34 S-SO 4 dynamics in stalagmite records (typical uncertainties (2σ): δ 18 O = 0.2‰ (Orland et al., 2019); δ 13 C = 0.6-0.7‰ (Oerter et al., 2016;Sliwinski et al., 2015); δ 34 S = 1.6‰ (1σ) at 70 ppm S concentrations (Wynn et al., 2010)). Whereas each of these isotope ratios reflects changing surface environmental conditions over inter-annual timescales, only the δ 18 O measurements by SIMS can produce records of intra-annual seasonality. ...
... Analysis of δ 13 C in speleothem carbonate cannot be undertaken simultaneously with δ 18 O, and any available records in the literature (e.g., (Pacton et al., 2013)) are not undertaken at seasonal resolution. The apparent lack of seasonal change in cave dripwater δ 34 S-SO 4 (Borsato et al., 2015) has also so far prevented SIMS speleothem sulphur isotope measurements at the seasonal scale (Wynn et al., 2010). Despite the clear advantages of utilising SIMS stable isotope analyses of speleothem carbonate to reveal seasonal patterns of rainfall delivery and drivers of climatic change, the technique also comes with its analytical challenges, including the considerable impact of geometric imperfections (e.g., sample topography, porosity, inclusions, cracks, etc) (Kita et al., 2011;Liu et al., 2015;Pacton et al., 2013;Treble et al., 2005a). ...
Stalagmites are an extraordinarily powerful resource for the reconstruction of climatological palaeoseasonality. Here, we provide a comprehensive review of different types of seasonality preserved by stalagmites and methods for extracting this information. A new drip classification scheme is introduced, which facilitates the identification of stalagmites fed by seasonally responsive drips and which highlights the wide variability in drip types feeding stalagmites. This hydrological variability, combined with seasonality in Earth atmospheric processes, meteoric precipitation, biological processes within the soil, and cave atmosphere composition means that every stalagmite retains a different and distinct (but correct) record of environmental conditions. Replication of a record is extremely useful but should not be expected unless comparing stalagmites affected by the same processes in the same proportion. A short overview of common microanalytical techniques is presented, and suggested best practice discussed. In addition to geochemical methods, a new modelling technique for extracting meteoric precipitation and temperature palaeoseasonality from stalagmite d18O data is discussed and tested with both synthetic and real-world datasets. Finally, world maps of temperature, meteoric precipitation amount, and meteoric precipitation oxygen isotope ratio seasonality are presented and discussed, with an aim of helping to identify regions most sensitive to shifts in seasonality.
... In order to evaluate whether CAS contributes to the observed Δ 18 O SIMS-GSMS , we reference analysis of a calcite speleothem, where CAS concentrations are known to track atmospheric SO 2 sourced by volcanogenic and anthropogenic emissions (e.g. Frisia et al., 2008;Wynn et al., 2010;Borsato et al., 2015). Consequently, CAS concentrations in speleothem calcite have increased by a factor of 10 (from <10 ppm to~100 ppm) during the past~150 years due to fossil fuel emissions (Frisia et al., 2008;Wynn et al., 2010;Borsato et al., 2015). ...
... Frisia et al., 2008;Wynn et al., 2010;Borsato et al., 2015). Consequently, CAS concentrations in speleothem calcite have increased by a factor of 10 (from <10 ppm to~100 ppm) during the past~150 years due to fossil fuel emissions (Frisia et al., 2008;Wynn et al., 2010;Borsato et al., 2015). Yet, Δ 18 O SIMS-GSMS values measured in a speleothem that grew continuously from pre-industrial to modern are temporally invariant within SIMS analytical precision (±0.5‰, 2SD; Orland, 2012 ...
The oxygen isotope (δ¹⁸O) compositions of final chamber fragments of individual shells of the planktic foraminifer Orbulina universa were measured in situ via secondary ion mass spectrometry (SIMS) and by traditional gas-source mass spectrometry (GSMS) entailing acid digestion of sampled calcite. The paired SIMS-GSMS analyses were performed on final chamber fragments of fossil shells taken from the top of a sediment core (Holocene) as well as shells grown in laboratory culture. Multiple iterations of SIMS-GSMS analyses were conducted on final chamber fragments treated with a variety cleaning protocols. The series of paired analyses yielded an average SIMS-GSMS δ¹⁸O offset (Δ¹⁸OSIMS-GSMS) of −0.9 ± 0.1‰ (±2 SE). The volume of material analyzed in 10-μm SIMS spots is ~10⁵ times smaller than that analyzed by GSMS; hence, the extent to which these Δ¹⁸OSIMS-GSMS values represent real differences in analyte vs. instrumental factors remains unclear. Possible contributing factors to the SIMS-GSMS δ¹⁸O difference include sample-standard mismatch by SIMS, differences in standardization of SIMS and GSMS, and non-calcite contaminants in samples. Although the two datasets are consistently offset, SIMS values reproduce inter-shell δ¹⁸O variability delineated by shell fragment GSMS values. This strong positive covariance proved useful for bringing the two datasets into agreement (i.e. Δ¹⁸OSIMS-GSMS = 0), and confirms that SIMS-based foraminifer δ¹⁸O values record changes in calcification temperature and/or δ¹⁸O of seawater. Whether shells of foraminifer taxa with differing microcrystalline structures, chemical composition, and/or preservation histories register a similar Δ¹⁸OSIMS-GSMS value is a subject of ongoing testing.
... Volcanic events have also been recognized in speleothems (Frisia et al. 2005(Frisia et al. , 2008, but the sulphur records in speleothems can be complicated, as issues arise because of assimilation of sulphate by vegetation, which leads to a smearing of the atmospheric signal when transmitted underground (Wynn et al. 2013). A particularly distinctive attribute of sulphate is its d 34 S composition (Wynn et al. 2008(Wynn et al. , 2010, which reflects the sulphate source and will assume importance when we consider atmospheric inputs later. ...
... Speleothem records (Frisia et al. 2005;Wynn et al. 2008Wynn et al. , 2010 commonly display a pollution imprint, but the sulphur records are not identical to the atmospheric changes. In the Crag Cave (Ireland) catchment, strong redox effects in the waterlogged aquifer led to changes in concentration and isotopic composition of sulphate, nullifying the anthropogenic signal. ...
... Speleothem S may be measured quantitatively via SIMS (e.g. Wynn et al., 2010). The approximate decline in dripwater SO 4 concentrations over the study period is 1.4 mg/l, calculated using the averages of the first and final six months of monitoring. ...
... Applying the partition coefficient for S/Ca from dripwater to speleothem used by Borsato et al. (2015), yielded an estimated decline in speleothem calcite equivalent to 47 ppm, well above the analytical precision of several ppm for SIMS (e.g. Wynn et al., 2010). ...
Forest biomass has the potential to significantly impact the chemistry and volume of diffuse recharge to cave dripwater via the processes of nutrient uptake, transpiration and forest fire. Yet to-date, this role has been under-appreciated in the interpretation of speleothem trace element records from forested catchments. In this study, the impact of vegetation is examined and quantified in a long-term monitoring program from Golgotha Cave, SW Australia. The contribution of salts from rain and dry-deposition of aerosols and dissolved elements from soil mineral and bedrock dissolution to dripwater chemistry are also examined. This study is an essential pre-requisite for the future interpretation of trace element data from SW Australian stalagmite records, whose record of past environmental change will include alterations in these biogeochemical fluxes. Solute concentrations in dripwater vary spatially, supporting the existence of distinct flow paths governed by varying amounts of transpiration as well as nutrient uptake by deeply-rooted biomass. Applying principal components analysis, we identify a common pattern of variation in dripwater Cl, Mg, K, Ca, Sr and Si, interpreted as reflecting increasing transpiration, due to forest growth. Mass-balance calculations show that increasing elemental sequestration into biomass has the largest impact on SO4, providing an explanation for the overall falling dripwater SO4 concentrations through time, in contrast to the transpiration-driven rising trend dominating other ions. The long-term rise in transpiration and nutrient uptake driven by increased forest bioproductivity and its impact on our dripwater chemistry is attributed to (i) the post-fire recovery of the forest understorey after fire impacted the site in 2006 CE; (ii) and/or increased water and nutrient demand as trees in the overlying forest mature. The impact of climate-driven changes on the water balance is also examined. Finally, the implications for interpreting SW Australian speleothem trace element records are discussed.
... Here, we describe and discuss the petrography and geochemistry of stalagmites from Obir cave in Austria (Spötl et al. 2005). Obir lies beneath an alpine forest at 1100 m altitude and the climatic context and ecological setting are comparable to that of the more extensively described Grotta di Ernesto in NE Italy Frisia et al. 2000Frisia et al. , 2003Frisia et al. , 2005Borsato et al. 2007;Wynn et al. 2010;Miorandi et al. in press) which lies 220 km to the WSW. Both caves contain stalagmites with distinct annual laminae as viewed in thin section. ...
... This parallels the impact of late 20th century pollution recorded in speleothem ER78 from Ernesto cave (Frisia et al. 2005). In work presented elsewhere (Wynn et al. 2010), we confirm this using the first in-situ micro-measurements of d 34 S in carbonateassociated sulphate. ...
... This parallels the impact of late 20th century pollution recorded in speleothem ER78 from Ernesto cave (Frisia et al. 2005). In work presented elsewhere (Wynn et al. 2010 ), we confirm this using the first in-situ micro-measurements of δ 34 S in carbonate-associated sulphate. ...
... Volcanic events have also been recognized in speleothems (Frisia et al. 2005(Frisia et al. , 2008, but the sulphur records in speleothems can be complicated, as issues arise because of assimilation of sulphate by vegetation, which leads to a smearing of the atmospheric signal when transmitted underground (Wynn et al. 2013). A particularly distinctive attribute of sulphate is its d 34 S composition (Wynn et al. 2008(Wynn et al. , 2010, which reflects the sulphate source and will assume importance when we consider atmospheric inputs later. ...
... Speleothem records (Frisia et al. 2005;Wynn et al. 2008Wynn et al. , 2010 commonly display a pollution imprint, but the sulphur records are not identical to the atmospheric changes. In the Crag Cave (Ireland) catchment, strong redox effects in the waterlogged aquifer led to changes in concentration and isotopic composition of sulphate, nullifying the anthropogenic signal. ...
Annually laminated stalagmites from natural caves and limestone mines capture a number of significant environmental and climatic signals during the anthropogenically disturbed era. The effects of forest clearance, or development of agricultural or industrial practices, can be marked by changes in soil or hydrological responses leading to shifts in both chemical (e.g. carbon and oxygen isotope ratios or trace elements) and physical (e.g. fabric, thickness of laminae) signals. However, these signals are diachronous because of the spatial heterogeneity of human societies. Twentieth-century changes in atmospheric composition are known from speleothems at several sites and demonstrate pollution disturbance of the sulphur cycle and the signal provided by the 1950s rise in radiocarbon caused by atmospheric nuclear tests. This latter is a global signal and hence a strong candidate to define the start of the Anthropocene, although other considerations, including comparison with instrumental archives, would favour an earlier timing. An attractive option is the climate amelioration marking the end of the Little Ice Age in the mid-nineteenth century, which is marked in Alpine and other Northern Hemisphere areas. Examples are illustrated from the Grotta di Ernesto cave to illustrate the appearance of a putative mid-nineteenth-century boundary.
... This combination of microanalytical methods was found to constrain both regional palaeoclimate patterns as well as provide more local hydrological information at an annual timescale resolution. Another investigation by Wynn et al. (2010) used SIMS-determined sulfur concentration and d 34 S values in speleothem collected from the European Alps as a an environmental monitoring tool applicable to the past century. The data set reported by Wynn et al. (2010) records both a steady increase in sulfur content and a decrease in d 34 S values until towards the end of the past century, interpreted as the result of human industrial activity. ...
... Another investigation by Wynn et al. (2010) used SIMS-determined sulfur concentration and d 34 S values in speleothem collected from the European Alps as a an environmental monitoring tool applicable to the past century. The data set reported by Wynn et al. (2010) records both a steady increase in sulfur content and a decrease in d 34 S values until towards the end of the past century, interpreted as the result of human industrial activity. Significant short-term excursions are superimposed on these trends, which have been interpreted as either due to changes in the cave environment or due to short, discreet events such as volcanic eruptions. ...
Advances in the chemical and isotopic characterisation of geological and environmental materials can often be ascribed to technological improvements in analytical hardware. Equally, the creation of novel methods of data acquisition and interpretation, including access to better reference materials, can also be crucial components enabling important breakthroughs. This biennial review highlights key advances in either instrumentation or data acquisition and treatment, which have appeared since January 2010. This review is based on the assessments by scientists prominent in each of the given analytical fields; it is not intended as an exhaustive summary, but rather provides insight from experts of the most significant advances and trends in their given field of expertise. In contrast to earlier reviews, this presentation has been formulated into a unified work, providing a single source covering a broad spectrum of geoanalytical techniques. Additionally, some themes that were not previously emphasised, in particular thermal ionisation mass spectrometry, accelerator-based methods and vibrational spectroscopy, are also presented in detail.
... Our study focused on sulfur, which occurs in HA in either its oxidized or its reduced form. The S species contained within calcite matrices provide valuable environmental indicators, as has been demonstrated for calcite from a number of environments, including sediments~Bostick et al., !, soils~Prietzel et al., 2008!, biominerals~Dauphin et al., 2003Cusack et al., 2008!, andspeleothems~Frisia et al., 2005;Wynn et al., 2010!. Oxidation degree and chemical environment of S provide a means of distinguishing between different sources of S, such as volcanic ash sulfate associated with minerals!, anthropic gas~SO 2 !, or reduced forms linked to organic matter. ...
... The suitability of S as a tracer element needs to be confirmed for different types of natural organic matter. S speciation in a natural matrix has already been used in studies of speleothems~Frisia et al., 2005;Wynn et al., 2010!; however, these studies only investigated the origin of the sulfate, which was found to be mostly detrital and atmospheric~pollution or volcanic input during stalagmite formation!. ...
Organic matter (OM) entrapped in calcite is regularly used for
environmental studies; however, incorporation mechanisms and types of
interaction remain poorly understood. This study used a new methodology
to investigate interactions between OM and the calcite matrix during
crystallization processes using humic acid entrapment. A multi-method
approach confirmed that OM is both adsorbed onto the calcite surface and
incorporated into the calcite lattice during crystallization. Our
results also confirm the log-linear correlation between fluorescence
intensity and calcite matrix OM concentration. Fourier transform
infrared spectroscopy (FTIR) showed that OM in colloidal conformation is
adsorbed onto the calcite surface as a result of the structure of the OH
stretching band. Based on synchrotron analysis (XRF and XANES), we also
developed a new method in which sulfur is used as a tracer for entrapped
humic acid and for locating the OM electrostatically adsorbed onto the
calcite surface. Changes in the sulfur environment, determined using
XANES, indicated partitioning during calcite crystallization due to the
effect of the matrix on OM incorporation. Desorption experiments
revealed the stability of the OM atomic structure and the layered nature
of that structure. These results have allowed us to devise a general
model of OM incorporation into calcite.
... Greenland ice cores show the increasingly industrial origins of sulfur from 1860 to 1970 CE by progressively lower δ 34 S values (Patris et al., 2002), a trend also observed in the Ernesto Cave reference section (Figure 12b; Borsato et al., 2023) and in fir trees near to the cave ( Figure 12c (Wolfe et al., 2013), alongside annual rates of reactive N production from agricultural fertiliser and NOx emissions from fossil fuel combustion (Holland et al., 2005); (c) Coevolution of ice core NO3 and δ 15 N for NO3 from GISP 2 Greenland ice core (Hastings et al., 2009) and nitrate concentrations from Law Dome and Siple Dôme Antarctic ice core (from Wolff, 2013). (Mayewski et al., 1990), and sulfur emissions from N. America and Europe (from Hoesly et al., 2018); (b) S concentration and δ 34 S from Ernesto cave, Italy (Frisia et al., 2005;Wynn et al., 2010;Borsato et al., 2023); and (c) S concentrations and δ 34 S in Abies alba from NE Italy (Wynn et al., 2014). ...
The Anthropocene Working Group (AWG) has concluded that the Anthropocene represents geological reality and should be linked with the plethora of stratigraphic proxies that initiate or show marked perturbations at around the 1950s, and should be defined using a Global boundary Stratotype Section and Point (GSSP). We propose formalizing the Anthropocene as series/epoch, terminating the Holocene Series/Epoch with a single Crawfordian stage/age. The GSSP should be located at the level where the primary marker shows a rapid increase in 239+240Pu concentrations (coinciding with a globally recognisable, isochronous signal of the first above-ground thermonuclear tests). The stratigraphic signature of the Anthropocene comprises: a) lithostratigraphic signals, including many new proxies, such as synthetic inorganic crystalline mineral-like compounds, microplastics, fly ash and black carbon, in addition to direct modification through human terraforming of landscape and indirect influences on sedimentary facies through drivers such as climate change; b) chemostratigraphic signals including inorganic and organic contaminants and isotopic shifts of carbon and nitrogen; c) fallout from above-ground nuclear weapons testing; d) stratigraphic effects of climate warming, sea-level rise and ocean acidification; and e) biostratigraphic signals, especially range and abundance changes characterised by unprecedented rates and extents of non-native species introductions, increased population and species extinction and extirpation rates. These correlative markers are present in many kinds of geological deposits around the world. This ubiquity of signals verifies that the Anthropocene can be widely delineated as a sharply distinctive chronostratigraphic unit in diverse terrestrial and marine depositional environments, and reflects a major Earth System change that will have geologically lasting consequences. As background, the Anthropocene was suggested as a new epoch by Paul Crutzen in 2000. The AWG was established in 2009 by the Subcommission on Quaternary Stratigraphy to examine the evidence for the potential inclusion of the Anthropocene in the International Chronostratigraphic Chart (ICC) and, if warranted, to formulate a definition and proposal. Various suggested start dates were considered, and the mid-20th century was found to be the only one associated with an extensive array of effectively globally isochronous geological markers reflecting the ‘Great Acceleration’ of population, industrialization and globalization. Alternative interpretations of the Anthropocene, including as an informal ‘event’, were considered in detail by the AWG and found to be inconsistent with the stratigraphic evidence.
... Hartland et al. (2012) also showed that transport was affected by particulate or colloid size, with all sizes more easily transported under high-flow conditions (when fractures are activated), while during low-flow particulates and small colloids decoupled. Speleothem sulfur and sulfate concentrations and their isotopes have been used to investigate industrial pollution and past volcanic activity, and sulfate isotopes enable pollution provenance as well as emissions quantification (Borsato et al., 2015;Wynn et al., 2008Wynn et al., , 2010. ...
From sediment cores to speleothems, environmental archives are helping us to understand the history of wildfires.
... Hartland et al. (2012) also showed that transport was affected by particulate or colloid size, with all sizes more easily transported under high-flow conditions (when fractures are activated), while during low-flow particulates and small colloids decoupled. Speleothem sulfur and sulfate concentrations and their isotopes have been used to investigate industrial pollution and past volcanic activity, and sulfate isotopes enable pollution provenance as well as emissions quantification (Borsato et al., 2015;Wynn et al., 2008Wynn et al., , 2010. ...
Wildfires affect 40% of the earth's terrestrial biome, but much of our knowledge of wildfire activity is limited to the satellite era. Improved understanding of past fires is necessary to better forecast how fire regimes might change with future climate change, to understand ecosystem resilience to fire, and to improve data‐model comparisons. Environmental proxy archives can extend our knowledge of past fire activity. Speleothems, naturally occurring cave formations, are widely used in paleoenvironmental research as they are absolutely dateable, occur on every ice‐free continent, and include multiple proxies. Recently, speleothems have been shown to record past fire events (Argiriadis et al., 2019, https://doi.org/10.1021/acs.analchem.9b00767; McDonough et al., 2022, https://doi.org/10.1016/j.gca.2022.03.020; Homann et al., 2022, https://doi.org/10.1038/s41467-022-34950-x). Here we present a review of this emerging application in speleothem paleoenvironmental science. We give a concise overview of fire regimes and common paleofire proxies, describe past attempts to use stalagmites to investigate paleofire, and describe the physical basis through which speleothems can record past fires. We then describe the ideal speleothem sample for paleofire research and offer a summary of applicable laboratory and statistical methods. Finally, we present four case studies from southwest Australia which: (a) explore the geochemistry of ash leachates, (b) detail how sulfate isotopes may be a proxy for post fire ecological recovery, (c) demonstrate how a catastrophic paleofire was linked to changes in climate and land management, and (d) investigate whether deep caves can record past fire events. We conclude the paper by outlining future research directions for paleofire applications.
... For example, Hobbs and Atkins (1990) reported more rapid vegetative regrowth in Banksia woodland after spring fires compared to autumn fires. The opposite loading of S compared to aerosolsourced Mg and Br on PC2 suggests that the predominant source of S within YD-S2 may be derived from the bedrock, however this is unlikely given that published studies from four different caves document that bedrock S contribution to dripwaters is minor (between 1.1% À 2.1%, Wynn et al., 2008;Wynn et al., 2010;Wynn et al., 2013). Rather, the positive relationship between S and bedrock sourced parameters such as Sr and Ba, may result from a pH control on S incorporation into speleothems (Wynn et al., 2014;Wynn et al., 2018). ...
Speleothem records of past environmental change provide an important opportunity to explore fire frequency and intensity in the past, and the antecedent climatic conditions leading to fire events. Here, fire sensitive geochemical signals in a stalagmite from Yonderup Cave, a shallow cave in Western Australia, are compared to well-documented wildfire events that occurred in recent decades. The results are extended to identify wildfires during the growth interval of the speleothem (1760 CE–2005 CE). Principal component analysis of the stalagmite time-series revealed distinct peaks in a combination of phosphorus and metal (aluminium, zinc, copper and lead) concentrations in response to known fire events, which are interpreted to have come from ash. Varying responses in the geochemical signal in the pre- and post-European colonisation period are likely linked to changes in land management, fire frequency and fire intensities. Of note is what we infer to be a particularly intense fire event concluded to have occurred in 1897 ± 5 CE, which climate sensitive proxies (δ¹⁸O and bedrock-derived elements) indicate was preceded by a multi-decadal dry period that began in the late 1860s. The intensity of the deduced fire event is supported by a peak in P that is 6.3 times higher than elsewhere in the speleothem, accompanied by a peak in Zn. It was also inferred that changes to the surface-cave hydrology occurred as a result of this event, indicated by increased input of colloidal organic material onto the stalagmite that was interpreted to be caused by shallow karst bedrock fracturing from the heat-induced deformation that is observed after intense fires. These findings show the potential for speleothems to provide dated records of fire intensity and recurrence intervals. Further development could lead to a better understanding of the climate-fire relationship and the effects of land-management practices on wildfire frequency and intensity.
... The concentration of sulphur in stalagmite samples can be used to reflect the atmospheric sulphur loading [3]. The chronologies of stalagmite can be obtained by absolute radiometric methods [5], however, the transmission of sulphur from atmosphere to soil, and eventually to stalagmite in the drip sites, can be significantly lagged by up to a few decades and attenuated due to secondary processes, such as uptake by vegetation [6,7], biogenic activity and soil storage [8,9]. ...
Variation of sulphur in annually laminated stalagmites can be used to infer the impact of past volcanic activities, anthropogenic pollution, and climate change due to increased bushfire activity. The synchrotron radiation micro-X-Ray fluorescence (SR-XRF) microprobe is a powerful tool to analyse and image sulphur recorded in stalagmites with micrometre resolution. However, access to SR-XRF beamlines can be limited, so researchers must select the most promising stalagmites for imaging. Benchtop micro-XRF is an effective tool for trace elemental analysis of speleothem samples and is a candidate for routine laboratory measurement of sulphur along stalagmite laminae and screening for SR-XRF. This study describes a protocol using matrix-matched standards to measure annual variations of sulphur at trace to percent level along the laminae of two Western Australian stalagmites, one of which already having been analysed using SR-XRF. Parameters that affected quantitation include X-ray tube voltage and current, spot size of the X-ray beam and stalagmite surface roughness and porosity. The use of a 20 μm X-ray spot size provides sub-annual spatial resolution that can be completed in an overnight scan. The features in a 1000 point micro-XRF analysis of sulphur along a 20 mm transect show good consistency with SR-XRF microprobe data. Micro-XRF mapping was also performed to produce chemical images on the stalagmite and compared with Raman and X-ray diffraction (XRD) to confirm that the stalagmite is exclusively calcite, with no aragonite, and that the source of sulphur in the samples was gypsum and anhydrite. Regions of very high sulphur in the micro-XRF maps were found to be artefacts due to diffraction of the incident beam but these could be efficiently removed by using a multiple point statistics approach to produce a clean image suitable for analysis of the laminae. This work shows the potential of micro-XRF for routine analysis of sulphur in stalagmites, and to streamline sample characterisation before SR-XRF imaging.
... However, the analysis of stable isotopes by SIMS now achieves a spatial resolution capable of allowing direct comparability between both isotopic and trace element indicators of seasonality (Orland et al., 2014). (Borsato et al., 2015) has also so far prevented SIMS speleothem sulphur isotope measurements at the seasonal scale (Wynn et al., 2010). Treble et al. (2005a) produced the first d 18 O record unambiguously linking seasonal cycles in speleothem oxygen isotopes to rainfall dynamics and corroborated these interpretations with trace element cycles and contemporary rainfall monitoring. ...
Stalagmites are an extraordinarily powerful resource for the reconstruction of climatological palaeoseasonality. Here, we provide a review of different types of seasonality preserved by stalagmites and methods for extracting this information. A new drip classification scheme is introduced, which facilitates the identification of stalagmites fed by seasonally responsive drips and which highlights the wide variability in drip types feeding stalagmites. This hydrological variability, combined with seasonality in Earth atmospheric processes, meteoric precipitation, biological processes within the soil, and cave atmosphere composition means that every stalagmite retains a different and distinct (but correct) record of environmental conditions. Replication of a record is extremely useful but should not be expected unless comparing stalagmites affected by the same processes in the same proportion. A short overview of common microanalytical techniques is presented, and suggested best practice discussed. In addition to geochemical methods, a new modelling technique for extracting meteoric precipitation and temperature palaeoseasonality from stalagmite δ¹⁸O data is discussed and tested with both synthetic and real-world datasets. Finally, world maps of temperature, meteoric precipitation amount, and meteoric precipitation oxygen isotope ratio seasonality are presented and discussed, with an aim of helping to identify regions most sensitive to shifts in seasonality.
... Lauritzen and Lundberg 1999;Finch et al. 2001;Finch et al. 2003;McMillan et al. 2005;Lachniet 2009). Particularly, minor-element geochemistry in speleothems strongly reflects the ambient chemical composition (Perrin et al. 2014) and thus speleothems constitute potential archives of past volcanic eruptions and, probably, their consequent environmental impact Frisia, Borsato, and Susini 2008;Wynn et al. 2010;Badertscher et al. 2014). ...
... Sulfur isotope (δ 34 S) analysis is routinely used to answer questions concerning paleodiet (Sayle et al., 2016;Kinaston et al., 2014;Nehlich et al., 2012;Privat et al., 2007;Richards et al., 2003), animal migration (Haché et al., 2014;Lott et al., 2003), and pollution Xiao et al., 2011;Wynn et al., 2010Wynn et al., , 2014Winner et al., 1989;Case andKrouse, 1980, 1978). To confidently use sulfur isotopes as a geographic proxy, it is necessary to establish spatial isotopic patterns in terrestrial biological systems. ...
Coastal proximity, wind direction, and amount of precipitation can all influence the distribution of marine sulfur on land. However, the relative importance of these different factors to vegetation is not well constrained, and previous research has been geographically limited. Here we use sulfur isotope (δ³⁴S) values for total sulfur in foliage to assess the spatial distribution of marine-derived sulfur (+15.6 to +21‰) on the island of Trinidad. We expected that plants that receive heavy precipitation and are located on windward coasts (along the east and north coasts) would have higher δ³⁴S values resembling marine sulfur, whereas areas with low precipitation or on leeward coasts (i.e. the west and southwest) would have lower values. Samples were collected along an east-west transect that spanned the island's width, as well as 18 additional sites across the island. As anticipated, along the transect, plant δ³⁴S values are highest on the windward coast (ca. +17.4‰). Values decline ca. 9‰ within 1.5 km, and another ca. 6‰ within 10 km from the east coast. Island-wide, plants from the north and northeast exhibit the highest δ³⁴S values (+16.2 to +20.4‰), while those from the southwest have markedly lower δ³⁴S values (ca. +9.6‰). Overall, we find that a marine sulfur signal is most pronounced for sites within 1.5 km of the ocean yet may still be detectable within 10 km of the ocean for sites that receive abundant precipitation or are on a windward coast. Our data also suggest that anthropogenically-derived sulfur is utilized by vegetation growing in roadside and urban settings on the island.
... 477aerosols as well as anthropogenic pollution (Frisia et al. 2005b, Wynn et al. 2010 Wolff et al., 2017). ...
Central European climate is strongly influenced by North Atlantic (Westerlies) and Siberian High circulation patterns, which govern precipitation and temperature dynamics and induce heterogeneous climatic conditions, with distinct boundaries between climate zones. These climate boundaries are not stationary and shift geographically, depending on long-term atmospheric conditions. So far, little is known about past shifts of these climate boundaries and the local to regional environmental response prior to the instrumental era. High resolution multi-proxy data (stable oxygen and carbon isotope ratios, S/Ca and Sr/Ca) from two Holocene stalagmites from Bleßberg Cave (Thuringia) are used here to differentiate local and pan-regional environmental and climatic conditions Central Germany through the Holocene. Carbon isotope and S/Ca and Sr/Ca ratios inform us on local Holocene environmental changes in and around the cave, while δ ¹⁸ O (when combined with independent records) serves as proxy for (pan-)regional atmospheric conditions. The stable carbon isotope record suggests repeated changes in vegetation density (open vs. dense forest), and increasing forest cover in the late Holocene. Concurrently, decreasing S/Ca values indicate more effective sulfur retention in better developed soils, with a stabilization in the mid-Holocene. This goes in hand with changes in effective summer infiltration, reflected in the Sr/Ca profile. Highest Sr/Ca values between 4 ka and 1 ka BP indicate intensified prior calcite precipitation resulting from reduced effective moisture supply. The region of Bleßberg Cave is sensitive to shifts of the boundary between maritime (Cfb) and continental (Dfb) climate and ideally suited to reconstruct past meridional shifts of this divide. We combined the Bleßberg Cave δ ¹⁸ O time series with δ ¹⁸ O data from Bunker Cave (western Germany) and a North Atlantic Oscillation (NAO) record from lake SS1220 (SW Greenland) to reconstruct the mean position of the Cfb-Dfb climate boundary. We further estimate the dynamic interplay of the North Atlantic Oscillation and the Siberian High and their influence on Central European climate. Repeated shifts of the Cfb-Dfb boundary over the last 4000 years might explain previously observed discrepancies between proxy records from Europe. Detailed correlation analyses reveal multi-centennial scale alternations of maritime and continental climate and, concurrently, waning and waxing influences of Siberian High and NAO on Central Europe.
... Other element ratios such as Sr/Ca or Ba/Ca also produce complementary information about hydrology (McDonald et al., 2007). In addition, sulphate concentrations in speleothems have been used as tracers of volcanic or anthropogenic inputs to the karst system (Borsato et al., 2015;Frisia et al., 2005;Wynn et al., 2008;Wynn et al., 2010;Wynn et al., 2014). ...
Speleothem trace elements are an important and effective tool for palaeoenvironmental reconstruction. They can be used to reconstruct a plethora of climate variables, and are a vital tool for improving our understanding of the climate system. This is particularly important given the on-going challenges of comprehending and tackling anthropogenic climate change. Only by thoroughly understanding controls on climate variability can we attempt to predict future change. This thesis presents a broad study of current speleothem trace element proxies. In addition to reviewing the current state of knowledge, this thesis presents several additions and developments to the speleothem trace element toolkit.
The 22 year ATM-7 trace element record from Belize has a greater than seasonal resolution, and a highly precise chronology. As a result of this exceptional chronology, combined with extremely high resolution LA-ICP-MS analysis, it is possible to detect the geochemical indicators of volcanic ash deposition. Principal Component Analysis identifies a clear signal of a multi-elemental input of trace elements at the beginning of the wet season following volcanic eruptions with ash reaching the cave site.
U/Ca variability in aragonitic speleothems is strongly influenced by the occurrence of Prior Aragonite Precipitation. The U/Ca record in Belizean stalagmite YOK-G strongly suggests that modern drying has occurred in Belize, primarily caused by a reduction in wet season rainfall. This is consistent with published stable isotope data from YOK-G, previously interpreted as the result of southward ITCZ displacement. These results strongly suggest that U/Ca values in aragonitic speleothems are excellent proxies for rainfall variability. This new tool, combined with the exceptional chronological control characteristic of aragonitic stalagmites and the high spatial resolution afforded by modern microanalytical techniques, should facilitate the construction of new exquisitely resolved rainfall records, providing rare insights into seasonality changes as well as long-term changes in local recharge conditions.
In the Bermudan stalagmite BER-SWI-13, magnesium concentrations record, via varying prior calcite precipitation, changes in local rainfall which appear to correspond to variation in the North Atlantic Oscillation (NAO). Through a different mechanism, phosphorous also correlates with changes in the NAO. We infer that local effective rainfall changes, influenced by NAO state, influence bioproductivity above the cave and thus the amount of phosphorous in dripwaters. Surprisingly, for a location such as Bermuda, we see no evidence of clear direct anthropogenic influence on speleothem chemistry. These results suggest that Bermudan speleothems are well situated to record basin scale climate changes in the North Atlantic.
Together, these three separate studies demonstrate the strength and versatility of high- resolution trace element analysis of speleothems. They establish new techniques of data analysis, new proxies, and the applications of existing proxies in new contexts to reconstruct palaeoenvironmental variables. Looking forward, these discoveries demonstrate that speleothem trace elements continue to have a great deal to offer to the field of palaeoclimate reconstruction, and that there are still new techniques and applications to be developed.
... Instead, to further corroborate our interpretation of the Uluu-2 δ 18 O record as indicator for moisture variations, we compare it with the sulfur-to-calcite (S/Ca) ratio obtained with µXRF. In general, variations in the sulfur concentrations in speleothems may reflect atmospheric sulfur variability because of sea spray, dust, volcanic activity, and/or industrial pollution (Frisia et al., 2005;Wynn et al., 2010). Sulfur aerosols in CA are mainly derived from gypsum sourced from the Caspian and Aral Sea regions (Kreutz and Sholkovitz, 2000). ...
Central Asia is located at the confluence of large-scale atmospheric circulation systems. However, the number of Holocene climate records is still low in most parts of this region and insufficient to allow detailed discussion and comparisons to disentangle the complex climate history and interplays between the different climatic systems. Here, we present the first stalagmite record from arid Central Asia (south-western Kyrgyzstan) by using δ¹⁸O, δ¹³C, and micro x-ray fluorescence (µXRF)-sulfur data spanning the last 5000 years. The cave hosting stalagmite Uluu-2 is ideally suited to identify past shifts in seasonal variations in precipitation in this part of the world. Comparison of instrumental and paleo-isotopic studies demonstrates that the Uluu-2 speleothem isotope composition faithfully records climate changes and responds to shifts in the proportion of moisture derived from mid-latitude Westerlies during the winter/spring season. The reconstructions suggest that the area was characterized by a dry climate from 4700 to 3900 yr BP, interrupted by a wet episode around 4200 yr BP. Further drier conditions also occurred between 4000 and 3500 yr BP. Wetter conditions were re-established at ca. 2500 yr BP, after another dry episode between 3000 and 2500 yr BP. With the exception of two short dry events (1150 and 1300 yr BP), the period after 1700 yr BP shows moderate to wet conditions. Regional comparisons suggest that the strength and position of the Westerly winds control climatic shifts in arid Central Asia, leading to complex local responses.
... In forested catchments, sulphate can be subjected to biogeochemical cycling above the cave (e.g., Likens et al., 2002). Sulphate sources and biogeochemical cycling have been extensively studied at Grotta di Ernesto (Wynn et al., 2010(Wynn et al., , 2013Borsato et al., 2015b) revealing that most of the sulphate (>97%) in soil water and dripwater derived from anthropogenic emissions and a delay of 15-20 years between the atmospheric deposition and the cave dripwater signal exists. This delay is related to the retention of sulphur in the soil and vegetation above the cave through processes of inorganic adsorption as well as biologically mediated processes (Wynn et al., 2013). ...
The reconstruction of robust past climate records from speleothems requires a prior understanding of the environmental and hydrological conditions that lead to speleothem formation and the chemical signals encoded within them. On regional-scales, there has been little quantification of the dependency of cave dripwater geochemistry on meteorology (net infiltration, temperature), environmental and geographical factors (elevation, latitude, soil activity, vegetation cover, atmospheric aerosol composition) and geological properties of the aquifer (lithology, porosity and thickness). In the present study, we analysed over 200 karst waters collected in 11 caves of the Trentino region (NE Italy). The caves span sub-humid Mediterranean to cold-humid temperate climates and infiltration elevations (Zinf) ranging from 355 to 2400 m a.s.l., corresponding to infiltration mean annual temperatures (MATinf) between 12 and 0°C. Since all the caves developed in pure carbonate rocks, soil pCO2 is found to be the main factor controlling the carbonate dissolution. For this reason, the parameters controlling the carbonate-carbonic acid system and calcite saturation state (SICC) are directly correlated with the MATinf, which influences the vegetation zones and eventually the production of CO2 in the soil. SICC linearly depends on MATinf (SICC = 0.09 MATinf – 0.4) and SICC = 0 is reached at Zinf = 1.66 km a.s.l., corresponding to a MATinf = 4.4°C. This point identifies the “speleothem limit” defined here as the elevation (or corresponding MATinf) above which no sparitic speleothem precipitation usually occurs. We demonstrate that due to temperature-forced changes in the soil and vegetation and subsequently SICC, the speleothem limit shifts to higher altitudes during maximum interglacial conditions. Speleothems from high altitude caves (1.5–2.5 km a.s.l.) thus can identify optimum interglacial periods. By contrast, speleothems formed at lower altitudes are better suited as archives of hydrological proxies. At altitudes below 1.2 km a.s.l., prior calcite precipitation (PCP) modifies percolating waters, particularly during periods of reduced infiltration. We introduce the use of the SiO2/Ca and SO4/Ca ratios in cave waters to complement Mg/Ca and Sr/Ca ratios as markers of PCP. SO4 and SiO2 are derived from atmospheric deposition and siliciclastic minerals in the soil zone, rather than carbonate host rocks (as in the case of Mg and Sr). By combing shifts to higher Mg/Ca, SiO2/Ca and SO4/Ca ratios along their characteristics PCP lines, we improve the robustness of the interpretation that this resulted from increasing PCP, rather than incongruent calcite dissolution (ICD). Our method permits the quantification of PCP between 0 and 40% for low elevation cave waters. This novel approach has important implications for speleothem-based paleoclimate studies where the distinction between PCP and ICD can be ambiguous and, in combination with Mg/Ca and Sr/Ca ratios, permits the quantification of net infiltration and/or rainfall amount from speleothem records.
... New technical developments, such as benchtop X-ray fluorescence microscopy and microanalysis of certain isotopes, may transform current understanding of some proxies (for example, the use of secondary ionization mass spectrometry for d 34 S, Wynn et al., 2010;Fike et al., 2015). New types of measurement (for example, phosphate in calcite, Shimura et al., 2014; or trace elements in pyrite, Large et al., 2014) will open new windows on past environments, but typically will require theoretical and experimental studies to fully unlock their potential. ...
Sedimentological insights underpin many of the important recent advances in understanding of Earth system behaviour in the Neoproterozoic Era. This article reviews three main areas: (i) chemical proxies and their preservation, with emphasis on carbonate facies; (ii) glacial and post-glacial facies, including their age constraints; III) sedimentary evidence for biotic innovations and responses. Chemostratigraphy plays an important role in ordering Neoproterozoic events and defining disturbances to the carbon cycle. There is increasing attention being paid to assessing the role of diagenetic origination or modification of chemostratigraphic signals. Alongside this, new criteria for identifying primary dolomite and precursor metastable phases such as ikaite have been developed. In respect of oxygenation, geochemical proxies substantiate the concept of a Neoproterozoic Oxygenation Event as a very gradual transition, the ocean being at any one time a heterogeneous assemblage of ferruginous, sulphidic and oxic conditions, with some evidence of increasing deep-sea oxidation through the Ediacaran Period. Techniques such as Fe-speciation need to be supplemented with proxies sensitive to suboxic conditions. More generally, it is predicted that petrographically constrained microanalytical studies will also become more important in reconstructing palaeoenvironmental conditions. The global distribution of Neoproterozoic glacial deposits combined with palaeomagnetic evidence supports the concept of panglaciations in which ice sheets reached sea-level in the tropics. Advances in radiometric dating have demonstrated the synchronous onset of global (Sturtian) glaciation at 717 Ma and the demise of a second (Marinoan) glaciation at 635 Ma and plausibly indicate long durations for each (55 Ma for Sturtian and 5 to 15 My for Marinoan). However, a compilation of radiometric dates indicates ambiguities indicating the need for further improvements to the radiometric and Sr-isotope database to understand events within the Sturtian time frame, the timing of onset of Marinoan glaciations, and age and synchroneity of individual negative δ13C anomalies. Sturtian deposits are typically thick, rift-related successions containing a range of environments influenced or dominated by dynamic glaciers, as well as ice-free marine intervals. Marinoan glacial deposits, by contrast, tend to be thin and continental. During the latter interval, oxygen isotope systematics of sulphate demonstrate that atmospheric CO2 was high as predicted by Snowball Earth theory, and that sedimentation was influenced by orbital forcing. The Sturtian record, by comparison, needs to be searched for evidence of cold-climate hiatuses on the one hand and orbital forcing on the other. Cap carbonate formation appears to have coincided with rising sea-levels following panglaciations. Snowball theory considers that they formed rapidly in the postglacial greenhouse, but an alternative model of slower formation with clastic sediment starvation during transgression may prove to be consistent with new data and models showing extensive glacier terminations on land. For all facies, but especially caps, the use of microanalytical techniques and holistic studies of petrogenesis are future priorities. There are important discrepancies between molecular clock predictions of early metazoan origination and the hard evidence from the sedimentary records which largely depend on local exceptional preservation by early diagenesis. A variety of life survived panglaciation, and there is little evidence that glaciations directly caused oxygenation or stimulated evolution. This article is protected by copyright. All rights reserved.
... Enhanced understanding of the climate factors governing variability in the incorporation of dead carbon, however, could help determine when and where 14 C records are more/less sensitive to variability in proportion of dead carbon incorporated in speleothems. Borsato et al. (this issue) build on a line of research investigating the fidelity of sulfur in speleothems as a record of historic anthropogenic SO 4 emissions and volcanic activity Frisia et al., 2005;Wynn et al., 2013Wynn et al., , 2010Wynn et al., , 2008. Gonzalez-Lemos et al. (this issue) develop a reconstruction of Holocene flood frequency, and explore the potential of quantitative reconstruction of flood magnitude using modern flood events. ...
... Plus récemment, l'apport des spectres de terres rares ( = rare earth elements, ou REE) pour contraindre l'origine de ces éléments a été proposé (ZHOU et al., 2008b). Par ailleurs, la double analyse des signatures isotopiques en δ 34 S et δ 18 O des sulfates a été développée récemment (WYNN et al., 2008;WYNN et al., 2010). (BAKER et al., 2000). ...
Calcareous deposits forming within caves, also known as speleothems, have become acknowledged paleoclimatic archives. One of their main interests is that they can be absolutely dated by Uranium-Thorium methods. However, traditionally used speleothem climatic proxies cannot be directly translated into environmental variables such as the mean annual temperature or the amount of annual rainfall. In some contexts, the variations of trace element concentrations in speleothem calcite could be linked to past climatic changes, but the robustness of trace element signals between speleothems of the same or nearby caves is still questionable.We determined by ICP-MS the concentrations of several families of chemical elements (alkaline-earth metals, uranium, rare-earth elements) in stalagmites from two caves located in Southern France (Villars cave in Dordogne and Chauvet Cave in Ardèche) spanning the last 50,000 years. The selected speleothems had already been dated and their stable isotope profiles had proven to record paleoenvironmental fluctuations occurring during three separate periods: the Marine Isotopic Stage 3 or MIS 3 (~50-30 ka), the Last Deglaciation (~20-10 ka), and the end of the Holocene (~2-0 ka).Variations of alkaline-earth metals recorded in two stalagmites from Villars Cave during MIS 3 are significant and robust. Notably, Sr concentrations follow the rapid climatic changes recorded in the Northern Hemisphere. Furthermore, several trace elements behave similarly during the Last Deglaciation in the Villars and the Chauvet Cave. Finally, changes of the vegetation cover above the cave are likely to have caused the synchronous fluctuations of the trace element and stable isotope contents that happened during the last two thousand years in Villars speleothems.Lastly, the partition coefficients of alkaline-earth metals, uranium and rare-earth elements were measured in different sites and conditions and proved to be very site-dependent.
... Recently, uranium (Siklosy et al., 2011), anthropogenic sulfate Wynn et al., 2008), and lead (McFarlane et al., 2013) were detected in speleothems in a specific context of pollution demonstrating their potential as archives for human impact on the environment. Wynn et al. (2010) and Frisia et al. (2005) showed that the sulfate in speleothem calcite is indicative of atmospheric pollution opening the possibility of speleothems to be archives of atmospheric pollution. ...
Lead concentrations and isotope ratios from two speleothems from the Han-sur-Lesse cave in southern Belgium were measured in order to study the ability of speleothems to act as archives of atmospheric pollution. To address this aim we analyzed trace elemental Al and Pb compositions by LA-ICP-MS and ICP-MS as well as Pb isotopes by MC-ICP-MS. The results help to identify three intervals characterized by particularly high enrichment of Pb: from 1880 to 1905 AD, from 1945 to 1965 AD, and from 1975 to 1990 AD. The speleothem record shows similar changes as the known historical atmospheric pollution level in Belgium. Lead isotope ratios discriminate between Pb sources and confirm that coal and gasoline combustion, combined with regional metallurgical activities, were the predominant Pb pollution sources in the stalagmites during the last 250 years. This study opens possibilities to determine anthropogenic versus natural metal sources in well-dated speleothem archives.
... This is also higher than noted so far in speleothems. For ex am ple, Wynn et al. (2010) re ported a mean con tent of S in un pol luted sam ples of sta lag mites the equalled 25 and 14 ppm, re spec tively from Ernesto Cave (It aly) and Obir Cave (Aus tria). Un for tu nately, com par i son of the an a lyt i cal data from phreatic speleothems is im pos si ble as their chem i cal compo si tions have not yet been pub lished. ...
Peculiar calcite speleothems developed in fissures in the Cergowa Sandstones were found in the Kle{ogonek}czany Quarry (Polish Western Carpathians). They represent flowstone and stalactites, rafts and various sparry crusts. Such speleothems, especially phreatic ones, are uncommon in the Outer Carpathians that are composed mainly of siliciclastic rocks of flysch type, with only limited calcium carbonate content. The speleothems analysed grew in vadose and phreatic conditions as well as at the air-water interface. Phreatic speleothems and thin rafts comprise calcite crystals of eccentric morphology. Based on their stable isotope composition the majority of the speleothems form two clusters. The first is characterized by δ18O values between -9.8 and -8.5‰ and of d13C values between -5.7 and -0.6‰ whereas the second cluster of samples yields δ18 O values between -9.4 and -7.3‰ and d13C values from -11.5 to -9.7‰. Speleothems grew between 230+14-13 ka and Holocene time. Phreatic speleothems, including massive rafts, precipitated from ascending water of deep circulation whereas vadose and water table speleothems crystallized from local infiltration water charged with soil CO2. Mixing of both waters in the shallow phreatic zone is plausible.
... hardwater effect, varying marine reservoir ages). A potential, but still underexploited, archive of local to regional paleovolcanism are speleothems, as changes in their sulphur concentration (incorporated as sulphate into speleothem calcite) seem to be closely related to fluctuations in atmospheric sulphur loads (Frisia et al., 2005(Frisia et al., , 2008Wynn et al., 2010). However, secondary processes, such as biogeochemical cycling , hydrological mixing and redox state in the soil (Wynn et al., 2013), delays the transmission of volcanic sulphur from the atmosphere through the soil zone and aquifer to the stalagmite. ...
Available online xxxx Editor: G.M. Henderson Keywords: Minoan eruption volcanic eruption stalagmite trace elements Turkey eastern Mediterranean Mounting evidence exists that variations in sulphur content in stalagmites are closely linked to changes in volcanic or anthropogenic atmospheric sulphur. The strong dependency of sulphur on soil pH and ecosystem storage, however, can result in a delay of several years to decades in the registration of volcanic eruptions and anthropogenic emissions by stalagmites. Here we present synchrotron-radiation based trace element analysis performed on a precisely-dated section of a stalagmite from Sofular Cave in Northern Turkey. As this section covers the time interval of the intensively studied Minoan volcanic eruption between 1600 and 1650 BC, we can test whether this vigorous eruption can be traced in a stalagmite. Of all measured trace elements, only bromine shows a clear short-lived peak at 1621 ± 25 BC, whereas sulphur and molybdenum show peaks later at 1617 ± 25 and 1589 ± 25 respectively. We suggest that all trace element peaks are related to the Minoan eruption, whereas the observed phasing of bromine, molybdenum and sulphur is related to differences in their retention rates in the soil above Sofular Cave. For the first time, we can show that bromine appears to be an ideal volcanic tracer in stalagmites, as it is a prominent volatile component in volcanic eruptions, can be easily leached in soils and rapidly transferred from the atmosphere through the soil and bedrock into the cave and stalagmite respectively. Highly resolved oxygen and carbon isotope profiles indicate that the Minoan eruption had no detectable climatic and environmental impact in Northern Turkey.
... Indeed, organic molecules entrapped in speleothems have been attributed to soil or canopy sources (Van Beynen et al., 2000;Blyth et al., 2007Blyth et al., , 2011. However, atmospheric inorganic deposits, such as sulfur, have been studied in speleothems (Frisia et al., 2005;Wynn et al., 2010), illustrating the ability of speleothems to record directly atmospheric deposits that have had little interaction with soils. ...
a b s t r a c t The analysis of PAHs (polycyclic aromatic hydrocarbons) in karst environments has provided an assessment of the vulnerability of karst water and the study of PAH records in stalagmites. The major source of PAHs has generally been considered to be the soil. In this study, we report the quantification of PAHs in the ecosystem compartments of a mountain karst system over a snow-melting period and the spring to summer dry period. PAH profiles in karst seepage waters were consistently similar to those in wet deposits, following the change in PAH profiles between winter and summer periods. However, PAH signatures of atmospheric wet deposits were modulated by a loss of the high molecular weight PAHs, which appear to accumulate in soils. A PAH mass balance was calculated during a summer storm event. This mass balance suggests that dry deposits and canopy throughfall could account for the PAH abundance in karst seepage waters. This study demonstrates the ability of organic hydrophobic com-pounds to be directly transferred from the atmosphere or canopy into seepage waters, giving new emphasis to the study of PAHs recorded in stalagmites.
... Recently, uranium (Siklosy et al., 2011), anthropogenic sulfate Wynn et al., 2008), and lead (McFarlane et al., 2013) were detected in speleothems in a specific context of pollution demonstrating their potential as archives for human impact on the environment. Wynn et al. (2010) and Frisia et al. (2005) showed that the sulfate in speleothem calcite is indicative of atmospheric pollution opening the possibility of speleothems to be archives of atmospheric pollution. ...
Speleothems are now regarded as valuable archives of climatic conditions
on the continents, offering the advantages of absolute U-series dating
relative to other continental climate proxy recorders such as lake
sediments and peat cores. High spatial resolution measurements of Mg, U,
Sr, Ba and Zn were realized by laser-ablation inductively coupled plasma
mass spectrometry in the Belgian Père Noël cave Holocene
stalagmite (Verheyden et al., 2000, 2008). The stalagmite of 65 cm long
was deposited from ~12000 years to ~2000 years dated by U/Th method. Mg,
Sr, Ba, U, and Zn are known as indicators for hydrological conditions
(e.g. Ayalon et al., 1999; Fairchild et al., 2000). Mg, Sr, Ba
concentrations are positively correlated (r> 0.7) with similar
changes in the δ 13C implying similar processes influence their
concentration changes. U has an inverse relationship with δ 13C.
The study suggests that trace elements in the Père Noël
stalagmite have the potential to provide high resolution insights into
variability in water recharge during the Holocene. References Ayalon
A., Bar-Matthews M. and Kaufman A., 1999. Petrography, strontium, barium
and uranium concentrations, and strontium and uranium isotope ratios in
speleothems as palaeoclimatic proxies: Soreq cave, Israel. The Holocene
9 (6), 715-722. Fairchild I.J., Borsato A., Tooth A.F.,Frisia S.,
Hawkesworth C.J., Huang Y., Mcdermott F. and Spiro B., 2000. Controls on
trace element (Sr-Mg) compositions of carbonate cave waters:
implications for speleothem climatic records. Chemical Geology 166,
255-269. Verheyden S., Keppens E. , Fairchild I.J., Mc Dermott F. and D.
Weis, 2000. Sr isotope geochemistry of a Belgian Holocene speleothem:
implications for paleoclimate reconstructions. Chemical Geology, 169:
131 144. Verheyden S., Genty D., Deflandre G., Quinif Y. and Keppens E.,
2008. Monitoring climatological, hydrological and geochemical parameters
in the Père Noël cave (Belgium): Implication for the
interpretation of speleothem isotopic and geochemical time-series.
International Journal of Speleology, 37(3): 221234
NanoSIMS has been widely used for in-situ sulfur isotopic analysis (³²S and ³⁴S) of micron-sized grains or complex zoning in sulfide in terrestrial and extraterrestrial samples. However, the conventional spot mode analysis is restricted by depth effects at the spatial resolution < 0.5–1 μm. Thus sufficient signal amount cannot be achieved due to limited analytical depths, resulting in low analytical precision (1.5‰). Here we report a new method that simultaneously improves spatial resolution and precision of sulfur isotopic analysis based on the NanoSIMS imaging mode. This method uses a long acquisition time (e.g., 3 h) for each analytical area to obtain sufficient signal amount, rastered with the Cs⁺ primary beam of ∼100 nm in diameter. Due to the high acquisition time, primary ion beam (FCP) intensity drifting and quasi-simultaneous arrival (QSA) significantly affects the sulfur isotopic measurement of secondary ion images. Therefore, the interpolation correction was used to eliminate the effect of FCP intensity variation, and the coefficients for the QSA correction were determined with sulfide isotopic standards. Then, the sulfur isotopic composition was acquired by the segmentation and calculation of the calibrated isotopic images. The optimal spatial resolution of ∼ 100 nm (Sampling volume of 5 nm × 1.5 μm²) for sulfur isotopic analysis can be implemented with an analytical precision of ∼1‰ (1SD). Our study demonstrates that imaging analysis is superior to spot-mode analysis in irregular analytical areas where relatively high spatial resolution and precision are required and may be widely applied to other isotopic analyses.
Analytical Archaeometry describes this interesting and challenging field of research - on the border between natural sciences (chemistry, spectroscopy, biology, geology) and humanities (archaeology, (art-)history, conservation sciences). It fills the gap between these two areas whilst focussing on the analytical aspects of this research field. The first part of the book studies the main analytical techniques used in this research field. The second part expands from the different types of materials usually encountered, and the final part is organised around a series of typical research questions. The book is not only focussed on archaeological materials, but is also accessible to a broader lay audience. Overall the book is clearly structured and gives insight into different approaches to the study of analytical providing extensive discussion on a wide range of techniques, materials, questions and applications. Due to the advances in analytical instrumentation and applications in this field, it is important to have all this information merged together. Academics as well as professionals in archaeology, art history, museum labs and conservation science will find this an invaluable reference source ensuring the reader is provided with the latest progress in this research field.
The Anthropocene, currently an informal term, being investigated as a potential series/epoch within the Quaternary System/Period. It represents a time when intensified anthropogenic impacts have caused the Earth System to depart from the comparatively stable conditions that characterized the Holocene Epoch. A Holocene/Anthropocene boundary may be best placed to coincide with a marked inflection in a wide array of environmental proxies at about the mid-20th century. A GSSP (Global Boundary Stratotype Section and Point) may be sought among a range of sedimentary environments that offer annual to seasonal resolution.
Atmospheric deposition is an important source of trace elements in speleothems. In a pilot study, atmospheric deposition was collected monthly from Shihua Cave in Beijing, North China, from November 2012 to October 2013, to tentatively investigate the annual fluxes and seasonal variations of the water-soluble rare earth elements (REEs) in atmospheric deposition. The study led to the following results: (1) the annual fluxes of all the soluble REEs were in the descending sequence Ce, 67.9 μg m ⁻² yr ⁻¹ ; La, 42.1 μg m ⁻² yr ⁻¹ ; Nd, 23.8 μg m ⁻² yr ⁻¹ ; Pr, 5.94 μg m ⁻² yr ⁻¹ ; Sm, 4.68 μg m ⁻² yr ⁻¹ ; Gd, 4.26 μg m ⁻² yr ⁻¹ ; Dy, 3.53 μg m ⁻² yr ⁻¹ ; Er, 2.10 μg m ⁻² yr ⁻¹ ; Yb, 2.00 μg m ⁻² yr ⁻¹ ; Eu, 0.90 μg m ⁻² yr ⁻¹ ; Ho, 0.77 μg m ⁻² yr ⁻¹ ; Tb, 0.61 μg m ⁻² yr ⁻¹ ; Lu, 0.32 μg m ⁻² yr ⁻¹ ; and Tm, 0.31 μg m ⁻² yr ⁻¹ . (2) The seasonal deposition fluxes of all the REEs displayed two peaks, one in the spring and the other in the autumn. Lower deposition fluxes were observed in the summer and winter. Changes in the rainfall amount and in turn soil moisture content, snow coverage of the earth surface, and atmospheric dust activity were responsible for the seasonal changes in the REE deposition fluxes. (3) Natural materials, especially wind-blown dust, were the dominant source of water-soluble REEs in atmospheric deposition. The relative contribution from anthropogenic materials, such as automobile emissions, increased significantly in the winter when the snow coverage was large and the atmospheric dust activity limited.
Carbon dioxide concentrations in caves are a primary driver of rates of carbonate dissolution and precipitation, exerting strong control on speleothem growth rate and geochemistry. Long-term cave monitoring studies in midlatitude caves have observed seasonal variability in cave pCO2, whereby airflow is driven by temperature contrasts between the surface and subsurface. In tropical settings, where diurnal temperature cycles are larger than seasonal temperature cycles, it has been proposed that caves will ventilate on daily time scales, preventing cave pCO2 from increasing substantially above atmospheric pCO2. By contrast, the relatively small temperature difference between the surface and subsurface may be insufficient to drive complete ventilation of tropical caves. Here we present results of an 8 year cave monitoring study, including observations of cave pCO2 and carbonate chemistry, at Jinapsan Cave, Guam (13.4°N, 144.5°E). We find that cave pCO2 in Jinapsan Cave is both relatively high and strongly seasonal, with cave pCO2 ranging from 500 to 5000 ppm. The seasonality of cave pCO2 cannot be explained by temperature contrasts, instead we find evidence that seasonal trade winds drive cave ventilation and modulate cave pCO2. Calcite deposition rates at seven drip sites in Jinapsan Cave are shown to be seasonally variable, demonstrating that speleothem growth rates in Jinapsan Cave are strongly affected by seasonal variations in cave pCO2. These results highlight the importance that advection can have on cave ventilation processes and carbonate chemistry. Seasonality in carbonate chemistry and calcite deposition in this cave affect the interpretation of speleothem-based paleoclimate records.
Speleothem-like deposits that develop underground in urban areas are an archive of the environmental impact of anthropic activities that has been little studied so far. In this paper, the sulfate content in shallow groundwater from northern Paris (France) is compared with the sulfur content in two 300-year-old urban carbonate deposits that grew in a historical underground aqueduct. The present-day waters of the aqueduct have very high sulfur and calcium contents, suggesting pollution from gypsum dissolution. However, geological gypsum levels are located below the water table. Sulfur content was measured by micro-X-ray fluorescence in these very S-rich carbonate deposits (0.5 to 1% of S). A twofold S increase during the second half of the 1800s was found in both samples. These dates correspond to two major periods of urbanization above the site. We discus three possible S sources: anthropic sources (industries, fertilizers…), volcanic eruptions and input within the water through gypsum brought for urbanization above the studied site (backfill with quarry waste) since the middle of the 19th century. For the younger second half of the studied section, S input from gypsum brought during urbanization was confirmed by the study of isotopic sulfur composition (δ(34)S=+15.2‰ at the top). For the oldest part, several sulfur peaks could be related to early industrial activity in Paris, that caused high local air pollution, as reported in historical archives but also to historical gypsum extraction. This study provides information on the origin and timing of the very high SO4(2-) levels measured nowadays within the shallow groundwater, thus demonstrating the interest in using carbonate deposits in urban areas as a proxy for the history of urbanization or human activities and their impact on water bodies.
Aragonitic speleothems are increasingly utilised as palaeoclimate archives due to their amenability to high precision U–Th dating. Proxy records from fast-growing aragonitic stalagmites, precisely dated to annual timescales, can allow investigation of climatic events occurring on annual or even sub-annual timescales with minimal chronological uncertainty. However, the behaviour of many trace elements, such as uranium, in aragonitic speleothems has not thus far been as well constrained as in calcitic speleothems. Here, we use uranium concentration shifts measured across primary calcite-to-aragonite mineralogical transitions in speleothems to calculate the distribution coefficient of uranium in aragonitic speleothems (derived DU = 3.74 ± 1.13). Because our calculated DU is considerably above 1 increased prior aragonite precipitation due to increased karst water residence time should strongly control stalagmite aragonite U/Ca values. Consequently, uranium concentrations in aragonitic speleothems should act as excellent proxies for effective rainfall. We test this using a high-resolution ICP-MS derived trace element dataset from a Belizean stalagmite. YOK-G is an aragonitic stalagmite from Yok Balum cave in Belize with an extremely robust monthly-resolved chronology built using annual δ¹³C cycles. We interpret seasonal U/Ca variations in YOK-G as reflecting changes in the amount and seasonality of prior aragonite precipitation driven by variable rainfall amounts. The U/Ca record strongly suggests that modern drying has occurred in Belize, and that this drying was primarily caused by a reduction in wet season rainfall. This is consistent with published stable isotope data from YOK-G also very strongly suggesting modern rainfall reductions, previously interpreted as the result of southward ITCZ displacement. Our results strongly suggest that U/Ca values in aragonitic speleothems are excellent proxies for rainfall variability. This new tool, combined with the exceptional chronological control characteristic of aragonitic stalagmites and the high spatial resolution afforded by modern microanalytical techniques, should facilitate the construction of new exquisitely resolved rainfall records, providing rare insights into seasonality changes as well as long-term changes in local recharge conditions.
Here, we seek to address four issues. Firstly, we use strontium isotope ratios and sulphate concentrations and isotope ratios to illustrate how the changing elemental composition of the atmosphere (reflecting windiness or pollution e.g.) can be recorded in speleothems, although in the case of sulphur there can be significant lag and storage effects in the soil-ecosystem. Secondly, we illustrate how the differential dissolution rates of calcite (faster) and dolomite (slower) influences alkaline earth element chemistry in caves and speleothems, and how the occurrence of prior calcite precipitation in seasonally dry caves can be a useful signature of aridity. Thirdly, the impact of drip hydrology on speleothems is illustrated with two examples. Enrichments in alkaline earth elements tend to correspond with drier conditions. Many elements are transported preferentially in colloidal complexes, as is particularly clearly illustrated in hyperalkaline environments where the colloids are stabilized. Seasonal increases in colloidal abundance tend to be associated with enrichments in stalagmites in associated elements. Fourthly, the annual temperature cycle is difficult to recognize directly, but is seen indirectly in terms of its impact on cave air circulation, and in turn on PCO2 , pH and hence sulphate concentrations in speleothems. Multiproxy approaches prove to be particularly valuable. © 2010 the European Mineralogical Union and the Mineralogical Society of Great Britain&Ireland.
Quantification of sulfur (S) deposition is critical to deciphering the environmental archive of S in terrestrial ecosystems. Here we propose a mixing model that quantifies S deposition based on the S isotope ratio (δS) in tree rings. We collected samples from Japanese cedar ( D. Don) stumps from two sites: one near Yokkaichi City (YOK), which is well known for having the heaviest S air pollution in the world, and one at Inabu-cho (INA) in central Japan, which has been much less affected by air pollution. The δS profiles at both sites are consistent with S air pollution and contributions of anthropogenic S. The minimum value in YOK is lower than the δS values of anthropogenic S or any other possible source. Because the δS in the tree rings is affected by fractionation in the forest ecosystems, we used a mixing model to account for the isotope effects and to distinguish the sources of S. Based on the model results, we infer that the peak of S emissions at YOK occurred sometime between the late 1960s and early 1970s (489 mmol m yr). This estimated value is comparable with the highest reported values in Europe. This is the first quantitative estimate of anthropogenic input of S in forest systems based on δS in tree rings. Our results suggest that tree ring data can be used when monitoring stations of atmospheric S are lacking and that estimates of S deposition using δS in tree rings will advance our understanding of the local-scale S dynamics and the effect of human activities on it.
This review aims to determine the challenges and perspectives of using conifer needles as samplers of particulate matter. The characteristics of these substrates are described and their advantages in monitoring air quality and in reconstructing recent pollution events and sources are highlighted. Monitoring air quality in this way enables the evaluation of the efficiency of improvements in air quality policies or in industrial off-gas abatement systems. The analytical procedures necessary for the effective exploitation of these samplers are assessed by critically discussing previously published analytical protocols. By supporting the discussion with original experimental data, the benefits of combining bulk (e.g., inductively coupled plasma atomic emission spectroscopy) and single particle analytical methods (e.g., scanning and transmission electron microscopy in association with spectroscopy) are highlighted. It is proposed that, if analytical protocols are tailored to the study of particulate matter collected by conifer needles, a reliable and cost-effective monitoring strategy could be widely adopted in many countries and used to reduce the impact of particulate matter on human health and the environment.
Monthly atmospheric deposition was collected in Northeast of Sichuan Province from August 2011 to July 2012. Contents of Na, Mg, Ca, K, Si, Sr, Ba and Zn in weak-acid leachable fraction (with pH values of ca. 2) of the deposition were determined using ICP-MS. The results indicated that the deposition fluxes of all these elements exhibited notable seasonal variations. For example, the deposition flux of Na increased with precipitation, suggesting a dominant derivation from wet deposition; whereas the fluxes of Ca, Ba, Si, Sr and Mg displayed higher values during winter or spring season, suggesting that these elements may be closely associated with atmospheric dust activity. The annual fluxes of these elements were remarkably different in value. Na had the highest flux of 30 497 microg x (10(2) cm2 x a)(-1), more than three orders of magnitude higher than the lowest flux of Ba of 27.4 microg x (10(2) cm2 x a)(-1).
Five fabrics were identified in Alpine and Irish caves on the basis of morphological and microstructural characteristics, and related to growth mechanisms and growth environment. Columnar and fibrous fabrics grow when speleothems are continuously wet, and from fluids at near equilibrium conditions (low supersaturation; SIcc < 0.35), through the screw dislocation mechanism. The highly defective microcrystalline fabrics form at the same supersaturation range as columnar fabric but under variable discharge and the presence of growth inhibitors. Dendritic fabrics, which have the highest density of crystal defects, develop in disequilibrium conditions (high supersaturation) under periodic very low-flow-regime periods that result in prolonged outgassing. Cave calcareous tufa forms in disequilibrium conditions. Only the calcite crystals of fabrics formed at low supersaturation seem to precipitate near-isotopic-equilibrium conditions.
Sulfur isotopes of sulfate have been measured in a discontinuous set of polar ice core samples from Summit, central Greenland, covering the preindustrial (from the fourteenth to the eighteenth century) and industrial (from 1872 to 1969 A.D.) periods. Results have been used to estimate the different source contributions to the deposited sulfate and their evolution along the last centuries. They indicate that the preindustrial background sulfate budget is slightly dominated on a year-round average by marine biogenic emissions, amounting to close to half of the non-sea-salt sulfate (49%). The second contribution is provided by continental sources of secondary sulfate, including background volcanism and, to a lesser extent, continental biota (44% of the non-sea-salt sulfate). Sulfur emitted by relatively weak eruptions is found to be largely depleted in 34S compared to bulk volcanic S, suggesting an efficient washout of the heavier isotope during the tropospheric transport. The impact of human-driven emissions on the sulfate deposited in central Greenland ice is visible in isotope data as early as 1870 A.D. The isotopic signature of anthropogenic sulfur deposited during the twentieth century is found to be constant (delta34S ~ +3.0 +/- 1.50/00), regardless of the changes of dominant source regions and emission processes. This signature is slightly but measurably lighter than the one reported for Arctic haze pollution events.
This study aims to establish evidence for the widespread existence of preserved high-resolution trace element variations in speleothems that may have climatic significance. Ion microprobe analysis of speleothems reveals that annual to sub-annual variations in element chemistry exist at five, shallow western European cave sites (Crag Cave, County Kerry and Ballynamintra, County Waterford. Ireland: Uamh an Tartair, Sutherland, Scotland: Grotte Pere-Noël, Belgium: Grotta di Ernesto, NE Italy) with widely varying climatic, geomorphic and geological settings. The variations are not restricted to species (Mg. Sr and Ba) known to substitute directly for Ca in the calcite lattice, but include H, F, Na and P, Phosphorus (as phosphate) displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element. The technique allows estimation of growth rate of speleothems at any interval of interest, which is one of several possible uses in palaeoclimatology.
Seasonality is encoded in palaeoproxies of secondary cave mineral deposits (speleothems) and the code is becoming cracked. The petrology of calcite stalagmites from Obir, an Alpine (1100 m altitude), perennially wet cave, was characterized by optical and electron backscatter diffraction, and their chemistry by bulk ICP-MS analysis, ion microprobe and synchrotronbased micro-X-ray fluorescence. Vadose water penetrates 70 m through Triassic limestones (with some Pb-Zn mineralization) to the chamber Säulenhalle where the stalagmites were collected. Strong seasonal ventilation in the cave leads to low PCO2 in winter associated with falls in speleothem sulphate S and increase in δ13C values. All samples display autumnal event lamination defined by a narrow, optically visible zone with increases in trace element concentrations, within which synchrotron studies have resolved mm-scale enrichments of Pb and Zn. Small-scale (10 μm) lateral trace element variations reflect alternate flat faces and rough crystal edges, influenced by high Zn content. The elemental covariations are consistent with the transport of Pb, Zn, P, F, Br and I adsorbed onto organic colloids in dripwater, but the final deposition may have been from aerosols and we propose this as a new mechanism requiring further investigation. This study represents the most complete demonstration of how chemical variations are powerful expressions of seasonal cave physiology in humid temperate caves, including the contrast between summer and winter conditions, and the preservation of sub-weekly events during the autumn season.
A synthesis of the biogeochemistry of S was done during 34 yr(1964–1965 to 1997–1998) in reference and human-manipulated forestecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. There have beensignificant declines in concentration (–0.44mol/liter-yr) and input (–5.44mol/ha-yr)of SO4
2– in atmospheric bulk wet deposition, and inconcentration(–0.64 mol/liter-yr) an d output (–3.74mol/ha-yr) of SO4
2– in stream water ofthe HBEF since 1964. These changes arestrongly correlated with concurrent decreases in emissions of SO2from the source area for the HBEF. The concentration and input ofSO4
2– in bulk deposition ranged from a low of 13.1mol/liter (1983–1984) and 211 mol/ha-yr(1997–1998) to a high of 34.7 mol/liter(1965–1966) and 479 mol/ha-yr (1967–1968), with along-term mean of 23.9 mol/liter and 336mol/ha-yr during 1964–1965 to 1997–1998. Despiterecentdeclines in concentrations, SO4
2– is the dominantanion in both bulk deposition and streamwater at HBEF. Dry deposition is difficult to measure, especially inmountainousterrain, but was estimated at 21% of bulk deposition. Thus, average totalatmospheric deposition was 491 and 323 mol/ha-yr during1964–1969 and 1993–1998, respectively. Based on the long-term34S pattern associated with anthropogenic emissions,SO4
2– deposition at HBEF is influenced by numerousSO2sources, but biogenic sources appear to be small. Annual throughfall plusstemflow in 1993–1994 was estimated at 346 molSO4
2–/ha. Aboveground litterfall, for thewatershed-ecosystemaveraged about 180 mol S/ha-yr, with highest inputs (190 molS/ha-yr) in the lower elevation, more deciduous forest zone. Weatheringrelease was calculated at a maximum of 50 mol S/ha-yr. Theconcentration and output of SO4
2– in stream waterranged from a low of 42.3mol/liter (1996–1997) and 309 mol/ha-yr(1964–1965), to a high of 66.1 mol/liter(1970–1971) and 849 mol/ha-yr (1973–1974), with along-term mean of 55.5 mol/liter and 496mol/ha-yr during the 34 yrs of study. Gross outputs ofSO4
2– in stream water consistently exceeded inputsin bulkdeposition and were positively and significantly related to annualprecipitationand streamflow. The relation between gross SO4
2–output and annual streamflow changed with time asatmospheric inputs declined. In contrast to the pattern for bulk depositionconcentration, there was no seasonal pattern for streamSO4
2– concentration. Nevertheless, stream outputs ofSO4
2– were highly seasonal, peaking during springsnowmelt, andproducing a monthly cross-over pattern where net hydrologic flux (NHF) ispositive during summer and negative during the remainder of the year. Nosignificant elevational pattern in streamwaterSO4
2– concentration was observed. Mean annual,volume-weightedsoil water SO4
2– concentrations were relativelyuniform by soil horizon andacross landscape position. Based upon isotopic evidence, much of theSO4
2– entering HBEF in atmospheric depositioncycles throughvegetation and microbial biomass before being released to the soil solution andstream water. Gaseous emissions of S from watershed-ecosystems at HBEF areunquantified, but estimated to be very small. Organic S (carbon bonded andestersulfates) represents some 89% of the total S in soil at HBEF. Some 6% exists asphosphate extractable SO4
2– (PSO4).About 73% of the total S in the soilprofile at HBEF occurs in the Bs2 horizon, and some 9% occurs in the forestfloor. The residence time for S in the soil was calculated to be 9 yr, butonly a small portion of the total organic soil pool turns over relativelyquickly. The S content of above- and belowground biomass is about 2885mol/ha, of which some 3–5% is in standing dead trees. Yellowbirch, American beech and sugar maple accounted for 89% of the S in trees, with31% in branches, 27% in roots and 25% in the lightwood of boles. The pool of Sin living biomass increased from 1965 to 1982 due to biomass accretion, andremained relatively constant thereafter. Of current inputs to the availablenutrient compartment of the forest ecosystem, 50% is from atmospheric bulkdeposition, 24% from net soil release, 11% from dry deposition, 11% from rootexudates and 4% is from canopy leaching. Comparing ecosystem processes for Sfrom 1964–1969 to 1993–1998, atmospheric bulk deposition decreasedby 34%, stream output decreased by 10%, net annual biomass storage decreased by92%, and net soil release increased by 184% compared to the 1964–1969values. These changes are correlated with decreased emissions of SO2from the source area for the HBEF. Average, annual bulk deposition inputsexceeded streamwater outputs by 160.0 75.3 SD molS/ha-yr,but average annual net ecosystem fluxes (NEF) were much smaller, mostlynegativeand highly variable during the 34 yr period (–54.3 72.9 SDmol S/ha-yr; NEF range, +86.8 to –229.5). While severalmechanisms may explain this small discrepancy, the most likely are netdesorption of S and net mineralization of organic S largely associated with theforest floor. Our best estimates indicate that additional S from dry depositionand weathering release is probably small and that desorption accounts for about37% of the NEF imbalance and net mineralization probably accounts for theremainder (60%). Additional inputs from dry deposition would result fromunmeasured inputs of gaseous and particulate deposition directly to the forestfloor. The source of any unmeasured S input has important implications for therecovery of soils and streams in response to decreases in inputs of acidicdeposition. Sulfate is a dominant contributor to acid deposition at HBEF,seriously degrading aquatic and terrestrial ecosystems. Because of the strongrelation between SO2 emissions and concentrations ofSO4
2– in both atmospheric deposition and streamwater at HBEF,further reductions in SO2 emissions will be required to allowsignificant ecosystem recovery from the effects of acidic deposition. Thedestruction or removal of vegetation on experimental watershed-ecosystems atHBEF resulted in increased rates of organic matter decomposition andnitrification, a lowering of soil and streamwater pH, enhancedSO4
2– adsorption on mineral soil and smallerconcentrations andlosses of SO4
2– in stream water. With vegetationregrowth, this adsorbedSO4
2– is released from the soil, increasingconcentrations andfluxes of SO4
2– in drainage water. Streamwaterconcentration ofSO4
2– and gross annual output ofSO4
2–/ha are essentially the same throughout theHubbard BrookValley in watersheds varying in size by about 4 orders of magnitude, from 3 to3000 ha.
Oxygen (O) and sulfur (S) isotope systematics in bog water sulfates were determined for six Sphagnum dominated wetlands located in the British Isles and the Czech Republic, Central Europe. Comparison of a polluted and unpolluted
site showed that 4 times higher atmospheric S inputs led to 3 times higher bog water sulfate concentrations and substrate
S concentrations, 3 times increased ranges of substrate S concentrations, and 3 times increased ranges of δ34S values. Sites with elevated atmospheric S inputs exhibited greater geochemical variability in wetland S species. Sulfate
O–S isotope composition of bog pore water at a depth of 40cm below surface differed from that of surface bog water, indicating
that dissimilatory bacterial sulfate reduction, a process known to discriminate against the heavier isotopes 18O and 34S, occurred in surface peat layers. While bacterial sulfate reduction remained to be one of the main isotope-selective processes
for sulfate in peat, it could not fully explain the O–S isotope systematics of peat waters. The ‘residual’ sulfate was not
simultaneously enriched in the heavier isotopes 18O and 34S. Mixing of residual sulfate following bacterial sulfate reduction with the product of S2− reoxidation, cleavage of esters, and isotope exchange reactions may have contributed to the decoupling of the δ34Sso4 and δ18Sso4 values. Large within-site differences in δ18Sso4 and δ34Sso4 (up to 13 and 15‰, respectively) indicated little communication between the 0 and 40cm peat depth at some sites. Extremely
high δ18Sso4 and δ34Sso4 values found in several peat bog water samples from Connemara (Ireland), Thorne Moors (England) and Ocean (Czech Republic)
were not seen in streams draining the wetlands. Direct runoff of atmogenic sulfate constituted a significant portion of the
bog outflow. At the wetland scale, zones of dissimilatory bacterial sulfate reduction form pockets whose lateral hydrological
fluxes are small.
Stalagmite ER78, from Grotta di Ernesto cave in NE Italy displays clear annual lamination consistent with its shallow depth below a forest ecosystem subject to autumnal peaking of water infiltration. Synchrotron radiation scanning micro-X-ray fluorescence analyses of heavy elements at European Synchrotron Radiation Facility beamline ID22, and light elements at ID21, with 1–3 μm resolution has been combined with data from ion microprobe analyses to reveal chemical variability across the visible layers of these annual laminae. A series of elements display a symmetrical peak, centered around the thin, dark layer at the top of each lamina. The peak concentration is ordered Y > Zn, Cu and Pb > P and Br. This hierarchy is thought to reflect the selectivity of transport of these elements, possibly by organic colloids flushed from the soil zone during autumn infiltration. Ion microprobe analysis indicates Na and F also increase, as does H, the latter reflecting increased microporosity. Sr displays a trough around the dark and thin autumn layer implying that its incorporation may be limited by competition with other elements. Mg and S show a different pattern of annual variation and Fe displays none. The trace metals, Br and Y display peak abundance in the early 20th century, which appears to reflect a period of tree-felling rather than a climatic anomaly. The results demonstrate the power of the high spatial resolution and low detection limits of the synchrotron technique, and its ability to produce quantitative maps that allow distinction of layered structure from that of isolated particles, or irregular inhomogeneities.
There are very few process studies that demonstrate the annual variation in cave environments depositing speleothems. Accordingly, we initiated a monitoring program at the Obir Caves, an Austrian dripstone cave system characterized by a seasonally changing air flow that results in a predictable pattern of high pCO2 during summer and low pCO2 in winter. Although similar seasonal changes in soil pCO2 occur, they are not directly connected with the changes in the subsurface since the dripwaters are fed from a well-mixed source showing little seasonal variation. Cold season flushing by relatively CO2-poor air enhances degassing of CO2 in the cave and leads to a high degree of supersaturation of dripwater with regard to calcite. Forced calcite deposition during the cold season also gives rise to a pronounced pattern of synchronous seasonal variations in electrical conductivity, alkalinity, pH, Ca and δ13CDIC which parallel variations recorded in δ13Ccave air. Chemical components unaffected by calcite precipitation (e.g., δD, δ18O, SiO2, SO4) lack a seasonal signal attesting to a long residence in the karst aquifer. Modeling shows that degassing of CO2 from seepage waters results in kinetically-enhanced C isotopic fractionation, which contrasts with the equilibrium degassing shown from the Soreq cave in Israel. The Obir Caves may serve as a case example of a dripstone cave whose seepage waters (and speleothems) show intra-annual geochemical variability that is primarily due to chemical modification of the groundwater by a dynamic, bidirectional subsurface air circulation.
Following the decline in sulphur deposition in Europe, sulphate dynamics of catchments and the reversibility of anthropogenic acidification of soils and freshwaters became of major interest. Long-term trends in sulphate concentrations and fluxes in precipitation/throughfall and freshwater of 20 European catchments were analysed to evaluate catchment response to decreasing sulphate deposition. Sulphate deposition in the catchments studied declined by 38-82% during the last decade. Sulphate concentrations in all freshwaters decreased significantly, but acidification reversal was clearly delayed in the German streams. In Scandinavian streams and Czech/Slovakian lakes sulphate concentrations responded quickly to decreased input. Sulphate fluxes in run-off showed no clear trend in Germany and Italy but decreased in Scandinavia, the Czech Republic and Slovakia. The decrease, however, was less than the decline in input fluxes. While long-term sulphate output fluxes from catchments were generally correlated to input fluxes, most catchments started a net release of sulphate during the early 1990s. Release of stored sulphate leads to a delay of acidification reversal and can be caused by four major processes. Desorption and excess mineralisation were regarded as the most important for the catchments investigated, while oxidation and weathering were of lesser importance for the long-term release of sulphate. Input from weathering has to be considered for the Italian catchments. Sulphate fluxes in German catchments, with deeply weathered soils and high soil storage capacity, responded more slowly to decreased deposition than catchments in Scandinavia and the Czech Republic/Slovakia, which have thin soils and relatively small sulphate storage. For predictions of acidification reversal, soil characteristics, sulphur pools and their dynamics have to be evaluated in future research.
During the last twenty-five years European emission data have been compiled and reported under the Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) as part of the work under the UNECE Convention on Long-range Transboundary Air Pollution (LRTAP). This paper presents emission trends of SO2 reported to EMEP and validated within the programme for the period 1980–2004. These European anthropogenic sulphur emissions have been steadily decreasing over the last twenty-five years, amounting from about 55 Tg SO2 in 1980 to 15 Tg SO2 in 2004. The uncertainty in sulphur emission estimates for individual countries and years are documented to range between 3% and 25%. The relative contribution of European emissions to global anthropogenic sulphur emissions has been halved during this period. Based on annual emission reports from European countries, three emission reduction regimes have been identified. The period 1980–1989 is characterized by low annual emission reductions (below 5% reduction per year and 20% for the whole period) and is dominated by emission reductions in Western Europe. The period 1990–1999 is characterised by high annual emission reductions (up to 11% reduction per year and 54% for the whole period), most pronounced in Central and Eastern Europe. The annual emission reductions in the period 2000–2004 are medium to low (below 6% reduction per year and 17% for the whole period) and reflect the unified Europe, with equally large reductions in both East and West. The sulphur emission reduction has been largest in the sector Combustion in energy and transformation industries, but substantial decreases are also seen in the Non-industrial combustion plants together with the sectors Industrial combustion and Industrial production processes. The majority of European countries have reduced their emissions by more than 60% between 1990 and 2004, and one quarter have already achieved sulphur emission reductions higher than 80%. At European level, the total sulphur target for 2010 set in the Gothenburg Protocol (16 Tg) has apparently already been met by 2004. However, still half of the Parties to the Gothenburg Protocol have to reduce further their sulphur emissions in order to attain their individual country total emission targets for 2010. It is also noteworthy that, contrasting the Gothenburg Protocol requirements, a growing number of countries have recently been reporting increasing sulphur emissions, while others report only minor further decreases. The emission trends presented here are supported by different studies of air concentrations and depositions carried out within and outside the framework of the LRTAP Convention.
There is a shortage of archives of sulfur that can be used to investigate industrial orvolcanic pollution in terrestrial catchments, but the role of S as a nutrient, coupled with sparse published evidence, suggests that trees are promising targets. We focused on two conifer species (Picea abies (L.) Karst and Abies alba Miller) from an Alpine site in NE Italy. Bulk analyses of Abies demonstrate that S concentrations were higher in the second half of the 20th century but with some high outliers possibly reflecting particulate impurities. X-ray synchrotron analyses confirmed the observed time trend, which is similar to that of a nearby stalagmite, and reflects an atmospheric pollution record mediated by storage in the soil and ecosystem. S and P were found to be localized in the inner cell wall (ca. 2 microm wide), local thickenings of which probably account for some outlying high values of S in synchrotron studies. S occurs as a mixture of oxidation states (0 to +0.5, +2, +5, and +6) which are consistent in space and time. The results indicate that wood older than a few years contains archive-quality S but that robust conclusions require multiple replicate analyses.
Only a few S isotope data from atmospheric precipitates are available. These results demonstrate the possibility to discriminate between sulfur burdens from different natural and/or anthropogenic sources. The ? 34 S patterns of the major suppliers of atmospheric sulfur are discussed. Their ? ranges overlap so completely that we cannot use S isotope data of atmospheric samples to calculate the net contribution rates from the individual sources at a global scale. For selected areas, however, such conclusions can frequently be drawn. The most reliable results are to be expected from areas with only two (at maximum three) major sulfur suppliers with well known S isotopic composition and large ? difference between the individual sources. Limitations are given mainly by the complex origin of atmospheric sulfur from a variety of different sources (especially in highly industrial regions) and by the broad ? ranges even in relatively “uniform” suppliers. Furthermore the fate of the sulfur compounds after emission to atmosphere may be quite complex. Additional fractionation processes efface the “fingerprint” character of the S isotope composition. In some cases these difficulties may be overcome, when the S isotope values are correlated with other geochemical data. DOI: 10.1111/j.2153-3490.1974.tb01969.x
Sulphur isotope abundance ratios can often be used to determine the relative magnitude of the contributions of natural and anthropogenic sources to atmospheric sulphur deposition. There is evidence that the δ 34S values of pre-industrial sulphur deposition were in some areas up to 10‰ higher than those of recent anthropogenic sulphur additions. Stable sulphur isotopes could therefore serve as a historical tracer of anthropogenic pollution, provided that the original isotopic composition of the deposited sulphur is preserved in historical archives. Ice cores and tree rings might provide the best records of changes in 34S/ 32S ratios caused by recent anthropogenic sulphur additions, because isotope fractionation during sulphur deposition and fixatiion in these historical archives is small. Only a few relevant data have been reported in the literature, since the ability isotopically to analyse microgram quantities of sulphur is needed for such investigations. Lake sediments, peat deposits, and (palaeo-)soils also have the potential to record chronologies of anthropogenic sulphur inputs. However, syn- and post-depositional sulphur transformations might significantly alter the sulphur isotopic composition in these archives. The isotopic integrity of the source signal might thereby be lost, but information on environmental changes in the catchment area might nevertheless be obtained. Although it is sometimes difficult to separate source versus process components of isotopic change, sulphur isotope abundance ratios can often be used as a valuable indicator of historical change in sulphur loading of natural ecosystems.
Until now, our knowledge of the sulfur isotopic composition of seawater through geologic time has depended on stable isotopic analysis of sulfate from evaporites. Owing to the sporadic occurrence of evaporites through time, the secular sulfur isotope age curve contains many gaps with little or no data. In order to fill in some of these gaps, particularly the Neogene, we have analyzed the sulfur isotopic composition of carbonate-associated sulfate in carbonate tests of planktonic foraminifera. Other investigators have shown that sulfate may occur in biogenic calcites either lattice-bound, as micro-fluid inclusions, in adsorbed phases, or as protein polysaccharides. Whatever the origin, the sulfur isotopic composition of this sulfate appears to be representative of that of the water in which the organism lived, as shown by results on recent calcareous foraminifera and macrofossils. Using this approach for study of Miocene to Recent pelagic marine sediments supplemented by new data for Miocene marine evaporites from the Gulf of Suez, we have found that theδ34S of seawater has decreased about 2.5‰ over the past 25 m.y. and that most of the decrease has occurred over the past 5 m.y., parallelling a decrease in theδ13C of dissolved oceanic bicarbonate from the same interval.Sedimentary redox models based on isotope records suggest that organic carbon and sulfide burial have both decreased over the past 5 m.y. Alternatively, an increase in weathering rates over the past 5 m.y. would not require a decrease in organic carbon or sulfide burial as long as the isotopic effect of the increased river input exceeds the isotopic effect of the burial of the reduced species. In either case, the net result would be a decrease in atmosphericpO2.
We report here the first speleothem time-series of the variability of sulphate, a species whose abundance in catchments is strongly influenced by atmospheric anthropogenic and volcanic sources. Annually-resolved archives of S, Mg, Si and P were generated by applying synchrotron radiation micro X-Ray Fluorescence (XRF) to two speleothems from different sites in northern Italy. X-ray absorption-edge spectrometry proves that the S is in the form of sulphate and XRF mapping demonstrates that S is within calcite and enriched zones are predominantly as layers. A post-1850 A.D. record from the Ernesto cave shows a substantial rise in sulphate, interpreted as reflecting the largely anthropogenically-forced variation of sulphate of the atmospheric boundary layer, moderated by some ecosystem storage. Analysis of the circa 5.2 to circa 5.0 ka interval of a speleothem from Savi cave, where ecosystem retention of S is likely to have been minimal, shows a spiky sulphate record, resembling that of ice cores. A series of sulphate peaks suggest that multiple volcanic sulphate aerosol emissions at that time. This probably enhanced summer temperature cooling thus favouring the preservation of the human mummy of Neolithic–Copper age, the “Iceman” on the watershed between Italy and Austria. Both examples illustrate the power of speleothems to record atmospheric sulphate variability.
Time-series O isotope profiles for three U–Th dated stalagmites have revealed that for much of the Holocene, a site on the Atlantic seaboard (SW Ireland) exhibits first-order δ18O trends that are almost exactly out of phase with coupled δ18O curves from two southern European sites (SE France and NW Italy). In the Irish stalagmite (CC3 from Crag Cave, SW Ireland), low δ18O at 10,000calyr BP reflects cool conditions. By the early to mid-Holocene (9000–6000calyr BP) δ18O had increased, reflecting the onset of warmer conditions on the Atlantic seaboard. This shift to higher δ18O was accompanied by a marked increase in the stalagmite extension rate, reinforcing our interpretation that this was a period of relative warmth. Except for an episode of increased extension rate about 5500yr ago, δ18O in the Crag stalagmite exhibits a gradual decrease, accompanied by declining extension rates between 7800 and 3500calyr BP, interpreted as a cooling trend. There is evidence for increases in both δ18O and stalagmite extension rate in the period from 3500calyr BP to the present day suggesting a return to warmer conditions on the Atlantic seaboard. In the stalagmite from NW Italy (ER76, Grotta di Ernesto, Trentino province) the early-Holocene (c. 9200-7800calyr BP) is characterised by high δ18O, probably indicative of warm and/or dry conditions. Exceptionally low δ18O from 7800 to 6900calyr BP at this site reflects a well-defined wet phase (Cerin wet phase). In the last three millennia, this stalagmite exhibits a shift to lower δ18O, interpreted as some combination of cooler and/or wetter conditions. Unlike the Irish stalagmite, the Italian sample does not show a correlation between δ18O and extension rate. Instead, its extension rate correlates roughly with δ13C, presumably reflecting a climate-driven vegetation change. In the early Holocene, δ18O in the French stalagmite (CL26, Grotte de Clamouse, Herault province, SE France) was low relative to its Holocene average. For much of the period since c. 3500calyr BP this stalagmite exhibits higher δ18O than in the early Holocene, suggesting warmer conditions. Like the Irish stalagmite, the French sample exhibits a well-defined correlation between δ18O and extension rate. Had drip-water availability been the dominant control on δ18O at this semi-arid site then higher δ18O would have been accompanied by lower, not higher extension rates. This suggests strongly that temperature rather than rainfall amount was the dominant control at this site. While conclusions regarding the patterns of climate variability on a continent scale must remain tentative because of the limited number of stalagmites studied we argue that early Holocene warm conditions on the Atlantic seaboard (Irish site) coincided with relatively cool conditions at the Clamouse site. By c. 3500yr ago the pattern appears to have been reversed.
Grotta di Ernesto is a cave site well suited for palaeoclimate studies because it contains annually laminated stalagmites and was monitored from 1995 to the end of 2008 for microclimate, hydrology and hydrochemistry. Long-term monitoring highlighted that cave drips show three different hydrological responses to rainfall and infiltration: (1) fast seasonal drips in the upper part of the cave, which are mostly fed by fractures, (2) slow seasonal drips, located at mid-depth in the cave characterized by mixed feeding and (3) slow drips, mostly located in the deeper gallery, which are fed by seepage flow from bulk porosity with a minor fracture-fed component. The slow drips display daily cycles during spring thaw. Monitoring also indicated that drip waters are only slightly modified by degassing within the soil zone and aquifer and by prior calcite precipitation. Hydrochemical studies show a clear seasonality in calcite saturation index, which results in most cave calcite precipitation occurring during late autumn and winter with similar amounts of precipitated calcite on most stalagmites, regardless of drip rate (discharge) differences. Drip rate, and drip rate variability, therefore, has a minor role in modulating the amount of annual calcite formation. In contrast, drip rate, when associated with moderate reduction in calcite saturation index, clearly influences stalagmite morphology. Increasing drip rate yields a passage from candle-, to cone- to dome-shaped stalagmites. Very high drip rates feed speleothems with flowstone morphology. In summary, monitoring provides information about the karst aquifer and how hydrology influences those physical and chemical characteristics of speleothems which are commonly used as climate proxies. Copyright © 2010 John Wiley & Sons, Ltd.
Solar variability and volcanic activity strongly interact with climate and the environment. Synchrotron radiation X-ray microfluorescence (micro-XRF) to an annually laminated Alpine stalagmite confirmed that annual laminae result from hydrological variability and changes in the duration of soil microbial degradation. The latter is modulated by solar variability. At the centennial timescale, growth rate and solar activity appear to be correlated with temperature change, with low temperatures at solar minima. By combining micro-XRF and absorption spectroscopy techniques (XANES), we also found that speleothems are a new archive of aerosol sulphate related to volcanic activity. Peaks in S-concentration from c. 5.2 to 5.0 ka bp in an Alpine stalagmite suggest that multiple volcanic sulphate aerosol emissions enhanced Mid-Holocene summer cooling, thus favouring the preservation of the Alpine Iceman mummy in a persistent ice casket.
Only a few S isotope data from atmospheric precipitates are available. These results demonstrate the possibility to discriminate between sulfur burdens from different natural and/or anthropogenic sources. The δ34S patterns of the major suppliers of atmospheric sulfur are discussed. Their δ ranges overlap so completely that we cannot use S isotope data of atmospheric samples to calculate the net contribution rates from the individual sources at a global scale. For selected areas, however, such conclusions can frequently be drawn. The most reliable results are to be expected from areas with only two (at maximum three) major sulfur suppliers with well known S isotopic composition and large δ difference between the individual sources. Limitations are given mainly by the complex origin of atmospheric sulfur from a variety of different sources (especially in highly industrial regions) and by the broad δ ranges even in relatively “uniform” suppliers. Furthermore the fate of the sulfur compounds after emission to atmosphere may be quite complex. Additional fractionation processes efface the “fingerprint” character of the S isotope composition. In some cases these difficulties may be overcome, when the S isotope values are correlated with other geochemical data.
Precise dating and correlation of past key volcanic eruptions over a wide geographic area in archives of past climate variability is necessary to support a direct causality between volcanism and climate changes. Research has mostly focused on ice cores and varved sediments, which capture a record of volcanic eruptions in geochemistry and the presence of tephra and criptotephra. Precisely dated cave carbonate deposits, collectively known as speleothems are other valuable palaeoclimate archives, and encode information on past volcanism in their sulphate concentration variability. Due to the physical characteristic of speleothems, detection of sulphate concentration variability requires techniques capable of high spatial resolution, very low limit of detection (ppm to ppb) and low background noise. Synchrotron radiation-based (SR) micro X-ray fluorescence (µXRF) and X-ray absorption near-edge spectrometry prove to be one of the most effective techniques to detect short-lived pulses of sulphate concentration increase, which may be interpreted as being related to atmospheric load due to volcanic eruptions. Here, we provide an overview of existing work as well as a novel interpretation of a SR µXRF-based sulphate series in an annually laminated stalagmite with robust chronology. Sulphate concentration peaks in the years 1815–1816, 1844 and 1947, possibly coinciding with Tambora, Krakatau, and Hekla eruptions. It is concluded that sulphate concentration in speleothems expand the potential to correlate volcanic eruption events at a global scale.
Opposite to greenhouse gases, sulphate aerosol particles are expected to cause climate cooling, but uncertainties exist about source variability and strength. We analysed an ice core from a European glacier to quantify source strengths of aerosol-borne sulphate over a 200-year period. Sulphate from emissions of SO2 increased by more than an order of magnitude during this century. This anthropogenic source is responsible for about 80% of total sulphate in the industrial period, and reflects emissions of west European countries. In the pre-industrial period mineral dust was the dominant contributor, followed by sulphate from SO2 emissions with volcanoes or biomass burning as possible sources.
We present a new inventory of global sulfur dioxide emissions from anthropogenic activities for the years 1980–2000. Emissions were estimated in 11 world regions using country-level emissions inventories and regional fossil fuel sulfur content information. Estimated global emissions in 1990 are 72 TgS with an estimated uncertainty of ±8% due to random errors with additional systematic errors that suggest that true emissions may be higher than this central value. We estimate that 56% of 1990 world emissions are from coal, 24% from oil, 15% from industrial processes and 3% from biomass burning. When our results are compared with other studies, they are similar at the global-mean level, but show marked differences at the regional level. Globally, emissions have been roughly constant from 1980 to the present. However, a significant shift has occurred in the spatial distribution of emissions. While 60% of global emissions in 1980 were from around the North Atlantic basin, this region contributed less than 40% of the global total by 1995 and will contribute even less in the future. Currently, based on our estimates, the centrally planned Asia (CPA) region, dominated by China, is the largest contributor to global sulfur dioxide emissions. A gridded data set for 1990 emissions is also produced, including a consistent seasonal cycle and a stratification of emissions into low and elevated releases. Implications for climate modeling and detection studies are discussed.
Variations in the abundance of stable isotope of sulfur, nitrogen and carbon in sulfate, nitrate and organic carbon, respectively, were studied in snow and air samples from high-alpine sites. Their suitability as a tool for characterizing the source regions which contribute to the pollution of the high-alpine areas was investigated.The contributions of different sources to a specific receptor site are generally unknown and depend on emission patterns and meteorological conditions. Measured isotope ratios reflect the actual superposition of the distinct source types under the assumption that no major isotope fractionation occurs during transport and deposition and that post-deposition isotope effects can be excluded. In order to study the relationship between source region and isotopic pattern, daily high-volume samplings of the atmospheric aerosol at Sonnblick (Austrian Alps, 3106 m asl) were combined with twice-daily backtrajectories and evaluated statistically. In addition, vertical snow profiles taken in pits at various locations in the Alps were analyzed. For their interpretation, a so-called snow calendar was constructed which relates specific snow strata to the dates of the respective precipitation events. Furthermore, the isotope ratios of hydrogen and oxygen in the snow samples were used to support the meteorological information.Main findings of the investigations are regional patterns of δ34S in airborne sulfates, the seasonality of nitrogen isotope composition in nitrates, and a pronounced isotopic difference in nitrates and sulfates of pre-industrial and modern origin, respectively.This study was part of EUROTRAC subproject ALPTRAC.
The hemispheric impact of industrial emissions upon atmospheric sulphur loading is reflected in the sulphur depositional history recorded in cores from ice sheets. However, these do not reveal regional variations. Recently deposited speleothems are used here as archives of regional sulphur depositional history at two locations within the United Kingdom and Ireland. δ34S-so4 and δ18O-so4 present within speleothem carbonate are measured for the first time as part of a dual isotope approach to decode the speleothem sulphur record. The largely refractory nature of δ34S-so4 under oxidising conditions enables source provenance of atmospheric SO2, whereas the complex cycles of isotopic exchange and fractionation during incorporation of oxygen into sulphate molecules enable δ18O-so4 signatures to yield insights into ambient environmental conditions and biogeochemical cycling in the ecosystem above the cave. δ34S-so4 values extracted from speleothem carbonate formed within Browns Folly Mine, UK, range from +3.5 to +5.5‰ and δ18O-so4 +10.3 to +13.7‰. Both signatures lie within the range expected from sulphate deposition in industrial locations and reflect the transfer of sulphate into speleothem calcite with little fractionation. However, δ18O-so4 signatures at Crag Cave, western Ireland, are isotopically heavier than expected and approach isotopic equilibrium with δ18O-h2o under reducing conditions. Dual isotope analysis of δ34S-so4 and δ18O-so4 optimises the correct identification of sulphur sources and biogeochemical cycling prior to incorporation into the speleothem record. At carefully selected cave sites where drip water flowpaths into the cave remain oxic, speleothems hold the potential to retain records of atmospheric sulphur loading at the local and regional scale.
The sulphur isotopic composition of ocean water sulphate was determined, using the SF6 method, for samples from various depths of the Geosecs Stations II and 3 and for a single Pacific Ocean surface sample. The total spread in values obtained is less than that found in previous studies and is consistent with the experimental precision except for one Geosecs II sample which has an unusually low δ34S value. The mean value, + 20.99%., is markedly different from the hitherto accepted value of +20.0%.. The difference is attributed to the greater accuracy obtained when SF6 rather than SO2 is used as the sample gas for sulphur isotope analysis.
Speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system. However, the climatological meaning of many speleothem records cannot be interpreted unequivocally; this is particularly so for more subtle shifts and shorter time periods, but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward.An explicit description of speleothem records as time series draws attention to the nature and importance of the signal filtering processes by which the weather, the seasons, and longer-term climatic and other environmental fluctuations become encoded in speleothems. We distinguish five sources of variation that influence speleothem geochemistry, i.e. atmospheric, vegetation/soil, karstic aquifer, primary speleothem crystal growth and secondary alteration, and give specific examples of their influence. The direct role of climate diminishes progressively through these five factors.We identify and review a number of processes identified in recent and current work that bear significantly on the conventional interpretation of speleothem records, for example:(1)speleothem geochemistry can vary seasonally and hence a research need is to establish the proportion of growth attributable to different seasons and whether this varies over time;(2)whereas there has traditionally been a focus on monthly mean δ18O data of atmospheric moisture, current work emphasizes the importance of understanding the synoptic processes that lead to characteristic isotope signals, since changing relative abundance of different weather types might control their variation on the longer-term;(3)the ecosystem and soil zone overlying the cave fundamentally imprint the carbon and trace element signals and can show characteristic variations with time;(4)new modelling on aquifer plumbing allows quantification of the effects of aquifer mixing;(5)recent work has emphasized the importance and seasonal variability of CO2-degassing leading to calcite precipitation upflow of a depositional site on carbon isotope and trace element composition of speleothems;(6)although much is known about the chemical partitioning between water and stalagmites, variability in relation to crystal growth mechanisms and kinetics is a research frontier;(7)aragonite is susceptible to conversion to calcite with major loss of chemical information, but the controls on the rate of this process are obscure.Analytical factors are critical in generating high-resolution speleothem records. A variety of methods of trace element analysis is available, but standardization is a common problem with the most rapid methods. New stable isotope data on Irish stalagmite CC3 compares rapid laser-ablation techniques with the conventional analysis of micromilled powders and ion microprobe methods. A high degree of comparability between techniques for δ18O is found on the millimeter to centimeter scale, but a previously described high-amplitude oxygen isotope excursion around 8.3 ka is identified as an analytical artefact related to fractionation of the laser-analysis associated with sample cracking. High-frequency variability of not less than 0.5‰ may be an inherent feature of speleothem δ18O records.
Annual growth rates and the ratio of dark to light-colored calcite within single annual laminae in three contemporaneously deposited Holocene speleothems from Grotta di Ernesto, an Alpine cave in northern Italy, respond to changes in surface temperature rather than precipitation. Based on monitoring of present-day calcite growth, and correlation with instrumental data for surface climatic conditions, we interpret a higher ratio of dark to light-colored calcite and the simultaneous thinning of annual laminae as indicative of colder-than-present winters. Such dark and thin laminae occur in those parts of the three stalagmites deposited from AD 1650 to 1713 and from AD 1798 to 1840, as reconstructed through lamina counting. These periods correspond to the well-known Maunder and Dalton Minima of solar activity. An 11-yr cyclicity in growth rate, coupled with reduced calcite deposition during the historic minima of solar activity, is indicative of a solar influence on lamina thickness. Spectral analysis of the lamina thickness data also suggests that the North Atlantic Oscillation variability influenced winter temperatures. Based on the present-day controls on cave calcite formation, we infer that high-frequency changes in solar activity modulated the seasonal duration of soil CO2 production.
Determination of annual lamination provides important additional constraints to radiometric dates on speleothems, both for dating the duration of specific growth intervals and optimizing growth models. In the absence of visible laminae, however, speleothem age models are reliant upon curve fitting through discretely dated points and are therefore inherently more uncertain than annual chronologies from laminae. Given that the impact of seasonality on speleothems is expected to be strong enough to generate an annual pulse in trace element chemistry regardless of whether or not visible or fluorescent growth laminae are visible, we demonstrate the potential for deriving high-resolution stalagmite chronologies from non-laminated samples using annual chemical variations in stalagmites from two Alpine caves (Obir, Austria and Ernesto, NE Italy). Trace element data were obtained by ion microprobe analyses for H, P, Mg, Na, Sr and Ba and the annual signal was sought using spectral and wavelet analysis. An automated chemical peak-counting software tool was developed in MATLAB©. It counts significant annual peaks using criteria of minimum amplitude in relation to the local standard deviation of signal variation and minimum separation between peaks determined by the thickness of the preceding layers. Verification of the tool using visibly laminated samples suggests the software is a reliable and accurate method of chronology building, with hit ratios greater than 0.93 and less than 0.75% false alarm occurrences. Used in conjunction with other dating methods such as radiocarbon, U–Th and sulphur peak dating, the automated chemical laminae chronology-building approach provides a more meaningful alternative to simple age-depth curve fitting for non-laminated samples.
Stable isotopes were used to analyze the submicron-size sulfate aerosol particles in the atmosphere over the Pacific Ocean, together with the air-mass back trajectories, in order to test the hypothesis of Charlson et al. (1987) who suggested that, over the remote ocean areas, the primary source of atmospheric nonseasalt (NSS) sulfate is marine emissions of dimethylsulfide (DMS). The observed results of isotopic fractionation between the seawater sulfate and NSS sulfate fractions was found to be consistent with the isotopic fractionation predicted for the transformation of the seawater sulfate to the atmospheric NSS sulfate via a DMS path way, supporting the hypothesis of Charlson et al.
Archived wheat (Triticum aestivum L.) grain and straw, and soil samples from the control plot of the Rothamsted Broadbalk Experiment, located in southeastern England and established in 1843, were used to investigate the effects of dramatically changing SO2 pollution inputs on the concentrations and stable isotope ratios (delta34S) of S in the samples. Representative coal samples from UK major coal fields were also determined for delta34S. Concentrations of S showed no clear trends in either grain or straw over the 155 years from 1845 to 1999. However, grain and straw delta34S decreased rapidly from 6 to 7/1000 in 1845 to -2 to -5/1000 in the early 1970s, and since then have increased to 0.5 to 2/1000 in the late 1990s. This pattern mirrored the trend of UK SO2 emissions over the 155 years. Both grain and straw delta34S correlated strongly and negatively with UK SO2 emissions (R2 > 0.89), but the relationships were different for the pre- and post-1970 data sets. Soil delta34S also decreased considerably, from 8.2/1000 in 1865 to 3.7 to 4.5/1000 during 1965-1999. A negative delta34S value was inferred for the anthropogenic S deposited at the experimental site before 1970, and further confirmed by negative delta34S values (-6 to -10/1000) found in the coal samples from southeastern England and southern Wales. Based on the S isotope ratios, we estimated that anthropogenic S contributed 62 to 78% of the S uptake by wheat at the peak of SO2 emissions, and accounted for 28 to 37% of the topsoil S in 1965.
Little is understood about the usefulness of sulfur isotopic ratios (sigma 34S) in tree rings because the sulfur content in rings is generally insufficient for analysis using conventional methods. We present sigma 34S values of the water-soluble and the organically bound sulfur fractions in rings of coniferous trees grown in Japan, analyzed using a large-volume oxygen bomb. Comparing the sigma 34S values of the organically bound fraction in tree rings with past atmospheric sulfur concentrations and with those of their sources, we find clear evidence that the sigma 34S values of the organically bound fraction in the rings are dependent upon the values of the atmospheric sulfur sources. The evidence suggests that the sigma 34S values in tree rings are a useful chronological proxy for evaluating possible causes of past atmospheric sulfur pollution.
Sulphur isotope measurements of submic-rometer sulphate aerosol particles over the Pacific Ocean Fairchild, I Annual to sub-annual resolution of multiple trace element trends in speleothems Modification and preservation of environmental signals in speleothems
- J Calhoun
- T Bates
- R J Charlson
- A Baker
- A Borsato
- S Frisia
- R W Hinton
- F Mcdermott
- A Tooth
Calhoun, J., Bates, T., Charlson, R., 1991. Sulphur isotope measurements of submic-rometer sulphate aerosol particles over the Pacific Ocean. Geophysical Research Letters 18, 1877–1880. Fairchild, I.J., Baker, A., Borsato, A., Frisia, S., Hinton, R.W., McDermott, F., Tooth, A., 2001. Annual to sub-annual resolution of multiple trace element trends in speleothems. Journal of the Geological Society, London 158, 831–841. Fairchild, I.J., Smith, C.L., Baker, A., Fuller, L., Spötl, C., Mattey, D., McDermott, F., E.I.M.F, 2006. Modification and preservation of environmental signals in speleothems
Potential and limitations of using sulphur isotope abundance ratios as an indicator for natural and anthropogenic induced environmental change. Isotope techniques in the study of environmental change
- B Mayer
Mayer, B., 1998. Potential and limitations of using sulphur isotope abundance ratios as an indicator for natural and anthropogenic induced environmental change. Isotope techniques in the study of environmental change. Proceedings of an international conference in Vienna, Austria. Pp 423-435. IAEA, Vienna Austria, 14-18th April 1997.
Isotopic composition of the major contributors to atmospheric sulphur
- Nielson
Global and regional anthropogenic sulphur dioxide emissions
- Smith
Twenty-five years of continuous sulphur dioxide emission reduction in Europe
- Vestreng
Stable sulfur isotope ratio indicates long-term changes in sulfur deposition in the Broadbalk Experiment since 1845
- Zhao