No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Temporal trends in gaseous mercury evasion from the Mediterranean seawaters
Abstract
Mercury evasion from seawaters is considered to be one of the main natural sources of mercury released to the atmosphere. The temporal evolution of this mechanism is related to biotic and abiotic processes that produce mercury in its elemental form and as DGM. The efficiency of these processes depends upon the intensity of the solar radiation, the ambient temperature of the air parcel above the seawater, and the water temperature. In the Mediterranean region, the magnitude of these mechanisms are particularly significant, due to favorable climate conditions and to the presence of large cinnabar deposits that cross the whole region; all these synergic factors yield significant evasional fluxes of mercury from the surface water during most of the annual period. In this work, mercury fluxes were measured by using a floating flux chamber connected to an atomic absorption analyzer. Photosynthetic active radiation (PAR) and UV components of the solar radiation were measured using the same system adopted in the EC 'ELDONet project'. The measurements of the mercury evasional fluxes were carried out at three sites of the northern Tyrrhenian Sea during 1998. Two sites were located at unpolluted and polluted coastal areas, and the third was an offshore site. The evasional flux showed a typical daily trend, highest at midday when the ambient temperature and solar radiation were at the maximum, and lowest, near to zero, during the night. Besides the day-night behavior, a seasonal trend was also observed, with minimum values during the winter period (0.7-2.0 ng/m2 h) and maximum values during the summer (10-13 ng/m2 h).
... Generally, the gaseous Hg fluxes at the WAI were significantly higher in summer (p < 0.05, Dunn's test) than autumn and spring at all sites ( Figure 3). The highest values of gaseous Hg fluxes found in summer are related to the intensity of the incident solar radiation, as observed in several studies conducted in both marine (e.g., [67,68,105]) and freshwater environments (e.g., [19,98,99]); in fact, solar radiation is a key factor in promoting a faster rate of DGM production in warmer periods via the photoreduction of Hg 2+ in surface waters and the subsequent evasion to the atmosphere The highest values of gaseous Hg fluxes found in summer are related to the intensity of the incident solar radiation, as observed in several studies conducted in both marine (e.g., [67,68,105]) and freshwater environments (e.g., [19,98,99]); in fact, solar radiation is a key factor in promoting a faster rate of DGM production in warmer periods via the photoreduction of Hg 2+ in surface waters and the subsequent evasion to the atmosphere [26,[106][107][108]. This was also confirmed in this study, as high DGM concentrations were detected in summer and the lowest in autumn in parallel with UV radiation intensity, which is most effective in systems with low DOC content that in turn allow for higher light penetration [24,26]. ...
... Generally, the gaseous Hg fluxes at the WAI were significantly higher in summer (p < 0.05, Dunn's test) than autumn and spring at all sites ( Figure 3). The highest values of gaseous Hg fluxes found in summer are related to the intensity of the incident solar radiation, as observed in several studies conducted in both marine (e.g., [67,68,105]) and freshwater environments (e.g., [19,98,99]); in fact, solar radiation is a key factor in promoting a faster rate of DGM production in warmer periods via the photoreduction of Hg 2+ in surface waters and the subsequent evasion to the atmosphere The highest values of gaseous Hg fluxes found in summer are related to the intensity of the incident solar radiation, as observed in several studies conducted in both marine (e.g., [67,68,105]) and freshwater environments (e.g., [19,98,99]); in fact, solar radiation is a key factor in promoting a faster rate of DGM production in warmer periods via the photoreduction of Hg 2+ in surface waters and the subsequent evasion to the atmosphere [26,[106][107][108]. This was also confirmed in this study, as high DGM concentrations were detected in summer and the lowest in autumn in parallel with UV radiation intensity, which is most effective in systems with low DOC content that in turn allow for higher light penetration [24,26]. ...
... This value is in agreement with those usually reported for lake water ( [35] and references therein). The highest values of gaseous Hg fluxes found in summer are related to the intensity of the incident solar radiation, as observed in several studies conducted in both marine (e.g., [67,68,105]) and freshwater environments (e.g., [19,98,99]); in fact, solar radiation is a key factor in promoting a faster rate of DGM production in warmer periods via the photoreduction of Hg 2+ in surface waters and the subsequent evasion to the atmosphere [26,[106][107][108]. This was also confirmed in this study, as high DGM concentrations were detected in summer and the lowest in autumn in parallel with UV radiation intensity, which is most effective in systems with low DOC content that in turn allow for higher light penetration [24,26]. ...
Gaseous exchanges of mercury (Hg) at the water–air interface in contaminated sites strongly influence its fate in the environment. In this study, diurnal gaseous Hg exchanges were seasonally evaluated by means of a floating flux chamber in two freshwater environments impacted by anthropogenic sources of Hg, specifically historical mining activity (Solkan Reservoir, Slovenia) and the chlor-alkali industry (Torviscosa dockyard, Italy), and in a pristine site, Cavazzo Lake (Italy). The highest fluxes (21.88 ± 11.55 ng m−2 h−1) were observed at Solkan, coupled with high dissolved gaseous mercury (DGM) and dissolved Hg (THgD) concentrations. Conversely, low vertical mixing and saltwater intrusion at Torviscosa limited Hg mobility through the water column, with higher Hg concentrations in the deep layer near the contaminated sediments. Consequently, both DGM and THgD in surface water were generally lower at Torviscosa than at Solkan, resulting in lower fluxes (19.01 ± 12.65 ng m−2 h−1). However, at this site, evasion may also be limited by high atmospheric Hg levels related to dispersion of emissions from the nearby chlor-alkali plant. Surprisingly, comparable fluxes (15.56 ± 12.78 ng m−2 h−1) and Hg levels in water were observed at Cavazzo, suggesting a previously unidentified Hg input (atmospheric depositions or local geology). Overall, at all sites the fluxes were higher in the summer and correlated to incident UV radiation and water temperature due to enhanced photo production and diffusivity of DGM, the concentrations of which roughly followed the same seasonal trend.
... This result was also reported by other studies [43]. The main factors that affect the increased levels of GEM concentration around midday are the enhanced ambient temperature and solar radiation during the day that prevail especially during August, and enhance the release of Hg 0 from surface water [11]. The enhanced evasion is linked to the increased photoreduction and biological activity [44]. ...
... During summer, the depth of the thermocline and temperature gradient in the surface water increased from the Western to the Eastern Basin of the Mediterranean [37]. The high water temperature may affect the biotic and abiotic processes that contribute to the evasion of Hg to the atmosphere [11]. In addition, the release of Hg 0 from the surface water is facilitated by solar radiation [11]. ...
... The high water temperature may affect the biotic and abiotic processes that contribute to the evasion of Hg to the atmosphere [11]. In addition, the release of Hg 0 from the surface water is facilitated by solar radiation [11]. According to [45], the coastal waters and especially shallow waters act as significant sources of gaseous mercury during summer. ...
Gaseous elemental mercury (GEM) was monitored in the atmosphere of a coastal site situated in the Northern Aegean Sea of Greece from August 2014 to January 2015. The selected sampling site is seldom impacted by human activities. Thus, it was possible to study the processes involved in natural terrestrial, aquatic, and atmospheric environments. The diurnal and monthly variations in the concentration of GEM as well as the factors influencing these variations were determined. The GEM concentrations were found to be in the range from 0.63 to 4.44 ng m–3 during data acquisition. The mean GEM concentration was about 1.04 ±0.30 ng m–3. Higher concentrations and variability were observed during the summer than in fall and winter. In addition, increased GEM concentrations were measured during midday. The diurnal and monthly variations in GEM were possibly affected by solar radiation, temperature, vegetation, and boundary layer height. Various peaks were observed for air masses of terrestrial origin, possibly due to the small extent of biomass burning as well as rainfall. The background concentrations of GEM in the studied coastal site were around 1.50 ng m–3. The sampling site is a complex environment as this coastal region has seasonal surface water in the mainland and extended areas of grassland and vegetated surfaces. All individual parameters of this area play significant roles in determining GEM concentrations.
... In autumn and winter, the same experimental sites were affected by the reduction of solar radiation, especially in the afternoon, resulting in lower GEM evasion fluxes. This seasonal variation was observed by Ferrara et al. (2000) in the Tyrrhenian Sea: in that study, the fluxes ranged between 10.1 ng m −2 h −1 in summer and 0.7 ng m −2 h −1 in winter that are considerably lower than those found in our study. A pos- sible explanation for this substantial difference could be due to the en- vironment where Ferrara et al. (2000) operated that is not contaminated by Hg and is located in an offshore area. ...
... This seasonal variation was observed by Ferrara et al. (2000) in the Tyrrhenian Sea: in that study, the fluxes ranged between 10.1 ng m −2 h −1 in summer and 0.7 ng m −2 h −1 in winter that are considerably lower than those found in our study. A pos- sible explanation for this substantial difference could be due to the en- vironment where Ferrara et al. (2000) operated that is not contaminated by Hg and is located in an offshore area. Here, the ex- change processes involved in the Hg biogeochemical cycle among sedi- ment, water, and atmosphere occur at reduced rates compared to a fish farm, where the water depth is, on average, about 1 m. ...
... Finally, the experimental setup cho- sen, such as accumulation in a closed (e.g. this study, Bagnato et al., 2013) or dynamic (e.g. Ferrara et al., 2000;Gårdfeldt et al., 2001 flux chamber, could also influence the obtained value. In other studies, authors have estimated the fluxes through the application of micrometeorological models that measure flux from a wide fetch and do not impact the area of interest (e.g. ...
A crucial step towards developing a more complete understanding of mercury (Hg) biogeochemical cycling in coastal environments is the measurement of the fluxes of gaseous elemental mercury (GEM), at the water-air interface (W-A interface). A floating flux chamber coupled with a real-time atomic adsorption spectrometer (Lumex-RA 915M) was applied to measure GEM concentrations, and to estimate the diurnal evasion flux at the W-A interface during three seasonal campaigns at four selected sites: two in a lagoon-based fish farm, one in an open lagoon environment highly impacted by long-term activities from the Idrija mercury mine (Slovenia), and an uncontaminated area of the Gulf of Trieste, the Bay of Piran (Slovenia). In this study, the regional background concentration measured at the uncontaminated site of atmospheric GEM (from 1.60 ± 0.95 to 2.87 ± 1.52 ng m ⁻³ ) was determined. GEM fluxes at the W-A interface were found to be significantly higher during the summer (from 51.2 ± 8.8 ng m ⁻² h ⁻¹ to 79.9 ± 11.4 ng m ⁻² h ⁻¹ ) and correlated to incident solar radiation and water temperature. This finding confirms the importance of these two parameters in the photoreduction and biotic reduction of Hg ²⁺ to dissolved gaseous mercury (DGM), which is volatile and easily released to the atmosphere in the form of GEM. These new insights will be of help for future estimates of Hg mass balance in one of the most contaminated areas in the Adriatic Sea.
... Such an approach is being used for the first time in the present study. The aim of this research is to (i) develop a mercury exchange model in the Adriatic Sea based on the wind parameterisation described by Nightingale et al. (2000); (ii) simulate DGM and RHg concentrations, and net reduction in the water compartment, considering preciously modelled deposition and concentrations in the atmosphere (Žagar et al., 2007, 2014) and measured concentrations in the ocean (Kotnik et al., 2015); (iii) run Hg exchange simulations using available real-time data from one-and twoway coupled models for a one-month period during the winter 2012 with an extreme Bora-wind event (Ličer et al., 2016); (iv) compare the results based on one-and two-way coupled models with other data on Hg exchange in the Adriatic and Mediterranean Seas (Andersson et al., 2007;Ferrara et al., 2000;Gårdfeldt et al., 2003;Gencarelli et al., 2014;Kotnik et al., 2015;Mastromonaco et al., 2017;Pirrone et al., 2001;Rajar et al., 2007;Žagar et al., 2007;Žagar et al., 2014); compare the exchange to the quantities estimated by Kotnik et al. (2015). In their manuscript Kotnik et al. (2015) assumed the atmosphere-ocean exchange in the Adriatic Sea to be overestimated. ...
... In order to enhance this estimation, the results of the AdriHg model were extrapolated to the entire year. As reported by Ferrara et al. (2000) and Pirrone et al. (2001), Hg emissions into the atmosphere in winter are significantly lower than in other seasons. In order to consider seasonality we calculated evasion by accounting for the variability of fluxes as reported in three studies: Pirrone et al. (2001) Table 3 depict seasonal multiplication factors calculated from the above studies and the annual quantity of evasion. ...
... estimated 2.67-fold higher evasion during the warmer half of the year (April-October);Ferrara et al. (2000) calculated seasonal evasion based on flux chamber ...
A new mercury (Hg) evasion model for the Adriatic Sea was developed accounting for the ocean mixed layer depth in order to decrease Hg depletion at the surface. Previously modelled airborne Hg species and measured Hg in the ocean were used. Simulations were run using one-and two-way coupled atmosphere-ocean models. Discrepancies in evasion between the applied coupling schemes were shown to be insignificant. The model was evaluated by applying various wind parameterisations and diffusive coefficient formulae. Relatively high discrepancies among the applied methods were observed. The results of a shorter simulation were extrapolated over a one-year period by applying a measurement-based adaptation. We obtained good agreement with previously published data on Hg evasion in the entire Mediterranean area, thus confirming the suitability of the new model for Hg evasion simulations. Model computations performed for the Adriatic Sea resulted in levels of evasion approximately two times lower than previously estimated.
... Three distinct sampling campaigns to determine Hg 0 fluxes at the water-air interface were performed for both sites during the period of the year characterised by higher irradiation and temperature, which may favour the gaseous exchanges of Hg between the aquatic and atmospheric compartment (Cizdziel et al., 2019;Ferrara et al., 2000;Nerentorp Mastromonaco et al., 2017). More specifically, measurements were performed during late spring (VN: May 2022; PR: June 2021), summer (VN: August 2020; PR: August 2019), and autumn (VN: November 2020, PR: November 2021), whereas no measurements were carried out in winter due to logistical difficulties; however, previously published data report that Hg 0 emission during the winter period in these sites might be relatively low compared to those observed in other seasons . ...
... This discrepancy may be explained by the different hydrodynamism of the selected sites. The PR site was located in an open coastal area subject to marked water turbulence due to waves and tides which could have favoured the release of Hg 0 at the water-air interface extending the surface boundary layer (Ferrara et al., 2000;Zappa et al., 2003). This enhancement is effective mostly when surface water is super-saturated in DGM with respect to the atmosphere (Castelle et al., 2009) which is likely what occurred in this study taking into consideration both the atmospheric Hg 0 levels recorded in ambient air before the chamber deployment (Ci) and the measured DGM concentrations. ...
The northern Adriatic Sea is well known for mercury (Hg) contamination mainly due to historical Hg mining which took place in Idrija (Slovenia). The formation of dissolved gaseous mercury (DGM) and its subsequent volatilisation can reduce the amount of Hg available in the water column. In this work, the diurnal patterns of both DGM production and gaseous Hg fluxes at the water-air interface were seasonally evaluated in two selected environments within this area, a highly Hg-impacted, confined fish farm (VN: Val Noghera, Italy) and an open coastal zone less impacted by Hg inputs (PR: Bay of Piran, Slovenia). A floating flux chamber coupled with real-time Hg0 analyser was used for flux estimation in parallel with DGM concentrations determination through in-field incubations. Substantial DGM production was observed at VN (range = 126.0-711.3 pg L-1) driven by both strong photoreduction and possibly dark biotic reduction, resulting in higher values in spring and summer and comparable concentrations throughout both day and night. Significantly lower DGM was observed at PR (range = 21.8-183.4 pg L-1). Surprisingly, comparable Hg0 fluxes were found at the two sites (range VN = 7.43-41.17 ng m-2 h-1, PR = 0-81.49 ng m-2 h-1), likely due to enhanced gaseous exchanges at PR thanks to high water turbulence and to the strong limitation of evasion at VN by water stagnation and expected high DGM oxidation in saltwater. Slight differences between the temporal variation of DGM and fluxes indicate that Hg evasion is more controlled by factors such as water temperature and mixing conditions than DGM concentrations alone. The relative low Hg losses through volatilisation at VN (2.4-4.6% of total Hg) further confirm that static conditions in saltwater environments negatively affect the ability of this process in reducing the amount of Hg retained in the water column, therefore potentially leading to a greater availability for methylation and trophic transfer.
... Hg enters the ocean in different ways and various forms; however, it is mainly released as Hg(0) (Andersson et al., 2011;Mason et al., 2012;Lamborg et al., 2014). Typically, air-sea Hg(0) fluxes are measured using two methods: the dynamic flux chamber (DFC) technique (Ferrara et al., 2000;Gårdfeldt et al., 2001;Gardfeldt et al., 2003;Bagnato et al., 2013) and the different gas exchange model (Andersson et al., 2008(Andersson et al., , 2011Kirk et al., 2008;Ci et al., 2011Ci et al., , 2015Wang et al., 2016;Mason et al., 2017;Marumoto et al., 2018;DiMento et al., 2019). The calculation methods include measuring Hg(0) concentrations in the air and water, and incorporate various hydrological and meteorological parameters. ...
... The standard DFC technique calculates the difference between the concentrations of Hg(0) in the ambient air entering the chamber and the concentrations of Hg(0) in the air leaving the chamber (Qureshi et al., 2012). Thus far, measurements of air-sea Hg(0) fluxes using this technique have mainly been conducted in coastal areas on small vessels or rubber boats (Ferrara et al., 2000;Bagnato et al., 2013). However, the oceanographic R/V Akademik M.A. Lavrentev is designed for research in the open ocean. ...
The Eastern Arctic Seas and the north-western Pacific are among the most poorly investigated areas as far as Hg cycling in marine systems is concerned. Continuous measurements of gaseous elemental mercury (Hg(0)) concentrations in the marine boundary layer and Hg(0) evasion fluxes from the sea surface were performed in these regions in fall 2018. Atmospheric Hg(0) concentrations of 1.02–2.50 ng/m³ were measured (average: 1.45 ± 0.12 ng/m³; N = 2518). Values in the Far Eastern Seas of Russia were lower compared to previous observations, presumably reflecting а global trend of decreasing atmospheric Hg(0). Concentration-weighted trajectory analysis highlighted three source regions influencing Hg(0) concentrations in the ambient air during the cruise: 1) the north-eastern China and the Yellow Sea region; 2) the Kuril-Kamchatka region of the Pacific Ocean and the region around the Commander and Aleutian Islands; and 3) the Arctic region. In the Arctic, sea-air Hg(0) evasion fluxes were at the same low levels as those observed earlier in the northern sea areas (0.28–1.35 ng/m²/h, average, 0.70 ± 0.26 ng/m²/h, N = 29). In the Eastern Arctic Seas, Hg(0) evasion fluxes were significantly dependent on river runoff. In the Arctic Ocean, they were negatively correlated with water temperature and positively correlated with salinity, suggesting a proximity to areas with contiguous ice and higher dissolved Hg(0) concentrations in the surface seawater. These findings are consistent with the hypothesis that the Arctic Ocean is a source of atmospheric Hg(0) during late summer and fall.
... Mercury (Hg) is a global pollutant released by natural agencies and anthropogenic activities (Zhou, Hopke, Zhou, & Holsen, 2019). Natural agencies include emission of Hg from vegetation, geo tectonics, forest fires, soil, and water (Ferrara, Mazzolai, Lanzillotta, Nucaro, & Pirrone, 2000). Anthropogenic sources include geological Hg mobilization, mining, extraction, and burning of fossil fuels which contain Hg as a trace contaminant to chlor-alkali industries (Pacyna et al., 2010). ...
... contains supplementary material, which is available to authorized users. occurred through scavenging aerosols and clouds (Ferrara et al., 2000). Dry deposition includes the direct intact of Hg from the atmosphere to terrestrial and water bodies. ...
Throughout continents, reservoirs tend to have elevated methylmercury (MeHg) concentration transformed from mercury (Hg/total Hg). This impact may be pronounced in the reservoir with less velocity of water during the charging period resulted in the deposition of sediments. In sediments on favorable conditions, methylation may be enhanced by the decomposition of flood organic material, which can release Hg and enhance microbial activity. However, much less is known about the transfer ratio of Hg and its form MeHg from sediment to biota in the hydrological reservoir during the dam charging phase. The objective of our study was to understand the interrelationship between total Hg and MeHg in two key components sediment and fish in the reservoir ecosystem. This study was performed at the Three Gorges Reservoir (TGR) located on upstream of the Yangtze River in China. At the TGR charging phase, during winter time, the water level was high due to blockade of water by Three Gorges Dam (TGD). Sediment and fish samples were collected in winter season for total Hg, MeHg, and several ancillary parameters. The results showed that total Hg in sediment samples of the winter season were ranged from 6.2 ± 0.001 to 193.3 ± 0.001 × 10−3 mg/kg, with an average value of 53.76 ± 51.80 × 10−3 mg/kg, and for MeHg was ranged from 12.1 ± 0.04 to 348.7 ± 0.16 × 10−2 ng/g, with an average value of 98.96 ± 93.07 × 10−2 ng/g. Total Hg and MeHg in fish samples of the winter season were from 42.48 ± 6.71 to 166 ± 52.56 ng/g, with an average value of 76.22 ± 31.23 ng/g, and from 21.09 ± 2.31 to 61.60 ± 13.30 ng/g, with an average value of 37.89 ± 11.96 ng/g. The relationship of total Hg and MeHg concentrations in fish to those of sediments from corresponding sites showed a negative relationship. This might include a strong association of total Hg with an inorganic component of sediment (e.g., bound to sulfides or coprecipitated with other metal oxides such as manganese and iron). The average concentration of fish MeHg found in this study, at rates greater than 1.72 g/day, was estimated hazardous to human health. This study concludes sediment was acting as sequestrate for total Hg and MeHg in TGR. The bioaccumulation of total Hg and MeHg in fish was not controlled by sediment further investigation about pathological routes and dietary habits of fish needed to be identified for total Hg and MeHg study in TGR.
... Salt-marsh plants, such as Halimione portulacoides that exists in our sampling area, enhance the vegetation-air Hg 0 fluxes during daylight [43]. A daily trend was observed elsewhere with nighttime GEM evasion fluxes 2 to 5-fold lower than such of the daytime probably due to solar radiation that affects the release of elemental mercury from surface waters during daytime [35]. The negative sign in some cases is due to transported elemental mercury from other places, nearby or faraway. ...
... The measurement of mercury fluxes in the bibliography extend up to 88.90 ng m -2 h -1 in surface waters, up to 46 ng m -2 h -1 in coastal sea and estuarine waters, up to 80 ng m -2 h -1 in open sea waters, from -375 ng m -2 h -1 up to 677 ng m -2 h -1 in wetlands and from -342 ng m -2 h -1 up to 517 ng m -2 h -1 in agricultural fields as it is reviewed in[8]. In the Mediterranean area the minimum values during the winter period were 0.70-2 ng m -2 h -1 and maximum values during the summer were 10-13 ng m -2 h -1[35]. In other study the values of mercury fluxes in Mediterranean open water extend up to 40.50 ng m -2 h -1[10]. ...
Coastal rural areas can be a source of elemental mercury, but the potential influence of their topographic and climatic particularities on gaseous elemental mercury (GEM) fluxes have not been investigated extensively. In this study gaseous elemental mercury was measured over Mediterranean coastal grassland located at Northern Greece from 2014 to 2015 and GEM fluxes were evaluated utilizing Monin-Obukhov similarity theory. The GEM fluxes ranged from -50.30 to 109.695 ng m-2 h-1 with a mean value equal to 10.501 ng m-2 h-1 ± 19.14 ng m-2 h-1. Concerning the peak events, with high positive and low negative GEM fluxes, those were recorded from the morning until the evening. Rain events were a strong contributing factor for enhanced GEM fluxes. The enhanced turbulent mixing under daytime unstable conditions led to greater evasion and positive GEM fluxes while during nighttime periods the GEM evasion is lower indicating the effect of atmospheric stability on GEM fluxes. The coastal grassland with its specific characteristics influences the GEM fluxes and this area could be characterized as source of elemental mercury. This study is one of the rare efforts in the research community to estimate GEM fluxes in a coastal natural site based on aerodynamic gradient method.
... Mg per year; Bagnato et al., 2015;Ferrara et al., 2000;Geyman et al., 2023;Lamborg et al., 2006;Mason, 2009;Nriagu, 1989;Pyle and Mather, 2003;Buseck, 1981, 1986). By comparison, emission estimates from geothermal 510 systems-while far fewer in number-span only two orders of magnitude (8.5--60 Mg per year in total globally; Bagnato et al., 2015Bagnato et al., , 2018Varekamp and Buseck, 1986). ...
The Multi-Compartment Hg (mercury) Modeling and Analysis Project (MCHgMAP) is an international multi-model research initiative intended to simulate and analyze the geospatial distributions and temporal trends of environmental Hg to inform the effectiveness evaluations of two multilateral environmental agreements (MEAs): the Minamata Convention on Mercury (MC) and Convention on Long-Range Transboundary Air Pollution (LRTAP). This MCHgMAP overview paper presents its science objectives, background and rationale, experimental design (multi-model ensemble (MME) architecture, inputs and evaluation data, simulations and reporting framework), and methodologies for the evaluation and analysis of simulated environmental Hg levels. The primary goals of the project are to facilitate detection and attribution of recent (observed) and future (projected) spatial patterns and temporal trends of global environmental Hg levels, and identification of key knowledge gaps in Hg science and modeling to improve future effectiveness evaluation cycles of the MEAs. The current advances and challenges of Hg models, emission inventories, and observational data are examined, and an optimized multi-model experimental design is introduced for addressing the key policy questions of the MEAs. A common set of emissions, environmental conditions, and observation datasets are proposed (where possible) to enhance the MME comparability. A novel harmonized simulation approach between atmospheric, land, oceanic and multi-media models is developed to account for the short- and long-term changes in secondary Hg exchanges and to achieve mechanistic consistency of Hg levels across environmental matrices. A comprehensive set of model experiments is developed and prioritized to ensure a systematic analysis and participation of a variety of models from the scientific community.
... Methylmercury is a chemical compound that is neurotoxic and can adversely affects mitochondria, lipids, and microtubules which will lead to neurotoxic chemicals accumulation such as aspartate, serotonin, and glutamate [19]. Estimates suggests that a cumulative total of 2200 metric tonnes of mercury is released into the atmosphere annually [20]. As the primary organ targeted by mercury, the brain exhibits negative neurological and behavioural effects in animals exposed to toxic mercury environments. ...
The escalation of industrial activities over the past century has significantly heightened human exposure to heavy metals, posing grave threat to the health as well as the environment. Cadmium, mercury, and lead are few of the many heavy metals. They are prevalent pollutants and are absorbed, retained, and accumulated within the human body. On the basis of the absorbed dosage, exposure route, and duration, the range of the toxicity fluctuate. While these metals are essential in limited quantities, excessive exposure can lead to severe health complications and disorders. This review examines the mechanisms and adverse effects of cadmium, mercury, and lead on human health when present in exceedingly large amounts.
... However, inorganic forms of arsenic, such as arsenite and arsenate, have been found to be particularly dangerous to human health because they are extremely carcinogenic to people and can lead to skin, bladder, liver, and other types of cancer. [39] Humans are exposed to arsenic through air, food, and water, with drinking water contamination being one of the major contributors to arsenic toxicity in more than thirty countries worldwide. [40,41]. ...
Although many heavy metals have bio-toxic effects on human biochemistry, some of them have bio-importance as trace elements. The most frequent heavy metals to cause human poisonings are arsenic, mercury, lead, chromium, cadmium, and iron. Their wide distribution in the environment and detrimental effects on people are the results of their numerous industrial, domestic, agricultural, medical, and technological applications. These metals' carcinogenicity has been attributed to defects in DNA repair following the induction of oxidative stress and DNA damage by these metals. Metal toxicity is dependent on the dose ingested, the route of exposure, and the duration of the exposure, and it can cause a variety of disorders as well as excessive damage from oxidative stress brought on by the production of free radicals. In this review, their manufacturing and use, potential for human exposure, and molecular mechanisms of toxicity are all examined. The purpose of this article review is to discuss the effects that specific heavy metals may have on human health. Keywords: heavy metals, occurrence, uses, potential effect, toxicity mechanism
... The DGM concentrations in coastal surface waters mainly range from ~10 to ~150 pg L − 1 and generally demonstrate typical diurnal pattern with low values during nighttime and high values during daytime, mainly due to the photochemical production of Hg(0) in surface waters (Zhang et al., 2006;Fantozzi et al., 2007;Ci et al., 2011aCi et al., , 2016b. Most of field measurements report the oversaturation of DGM in surface waters with respect to the overlaying air and the positive Hg(0) emission fluxes of ~10 • -10 1 ng m − 2 h − 1 to the atmosphere (Ferrara et al., 2000;Gårdfeldt et al., 2003;Zhang et al., 2006;Castelle et al., 2009;Ci et al., 2011a;Floreani et al., 2019). The data and patterns of DGM and Hg(0) fluxes reported by these studies are comparable to our Wet− Light treatments, highlighting that the existing data and knowledge on aquatic Hg redox chemistry and air− sea water Hg(0) exchange can be used to explore the air− water Hg(0) exchange over tidal flats during high tide. ...
Gaseous mercury (mainly elemental mercury, Hg(0)) exchange between air and Earth's surfaces is one of the most critical fluxes governing global Hg cycle. As an important and unique part of intertidal ecosystem, tidal flat is characterized by periodic inundation and exposure due to tidal cycle, generating varying hydrological, photochemical and biogeochemical processes. However, quantitative and mechanistic understanding of Hg(0) dynamics between air and exceptionally dynamic tide flats has remained limited to date. In this study, we select five representative tidal flat sediments from typical coastal habits of Chinese coastlines to perform laboratory incubation experiments for deciphering the effect of the interaction of tidal cycle and solar radiation on Hg(0) dynamics over tidal flats with different sediment compositions. We show that sediment Hg concentration, tidal cycle and solar radiation collectively modulate the air-surface Hg(0) exchange over tidal flats and highlight that the photochemistry dominates the Hg(0) production and emission over tidal flats. We find that the daytime inundation presents highest Hg(0) emission fluxes for Hg-poor sediment, but the daytime exposure is the hot moment of Hg(0) emission from Hg-rich sediments and substantially contributes to daily Hg(0) emission fluxes. In the treatment to mimic semidiurnal tide, the daily Hg(0) fluxes are positively correlated to sediment Hg concentrations. Combining our mechanistic insights on air-surface Hg(0) exchange over tidal flats and related data and knowledge reported by other studies, we discuss the implications of our study for field measurement and model development of Hg(0) dynamics over highly dynamic tidal flats. We conclude that the air-surface Hg(0) dynamics over tidal flats are extremely complex and highly variable, and a greater understanding the interactions between natural processes, human impacts and climate forcings will better constrain current and future Hg biogeochemical cycle in global tidal flats.
... Ghosh et al., 2007 further added that, a continuous exposure of some heavy metals may result to a progressive muscular, physical and neurological diseases such as Parkinson's disease, Alzheimer's disease, muscular dystrophy and multiple sclerosis and might as well cause cancer. Due to this, knowledge on heavy metals is very significant in details to allow appropriate protective action against intemperate contact with the human body (Ferrara, 2000). ...
The goal of this study was to determine the amounts of certain heavy metals (Cr, Fe, Mn, Pb, and Zn) in milled millet and maize samples collected from ten (out of the twenty biggest) communities in the Accra Metropolis of Ghana's Greater Accra Region. Control samples of millet and maize were also generated to help determine if the heavy metals found in the samples were caused exclusively by the milling process. Heavy metals in milled samples were quantified using an AAS (spectrAA 220FS, Varian brand). 0.3860 ± 0.0077 mg/kg, 2.3365 ± 0.2365 mg/kg, 0.8253 ± 0.049 mg/kg, 0.3064 ± 0.0373 mg/kg, and 2.0668 ± 0.3281 mg/kg were reported as mean values of Cr, Fe, Mn, Pb and Zn respectively in milled millet samples. The average values for milled maize samples of Cr, Fe, Mn, Pb and Zn were 0.5021 ± 0.0171 mg/kg, 1.7800 ± 0.1752 mg/kg, 0.5378 ± 0.0330 mg/kg, 0.2986 ± 0.0228 mg/kg, and 1.7266 ± 0.2893 mg/kg respectively. With the exception of Pb, all of the heavy metals tested showed average amounts that were within WHO/FAO acceptable levels. Because the grains come into direct touch with the attrition plates in disk attrition mills, heavy metals were found to leach into milled samples. However, when milled samples of maize and millet were compared to pounded (control) samples, Zn was shown to be lower in milled samples of both maize and millet.
... Ghosh et al., 2007 further added that, a continuous exposure of some heavy metals may result to a progressive muscular, physical and neurological diseases such as Parkinson's disease, Alzheimer's disease, muscular dystrophy and multiple sclerosis and might as well cause cancer. Due to this, knowledge on heavy metals is very significant in details to allow appropriate protective action against intemperate contact with the human body (Ferrara, 2000). ...
... As reported by Ballabio et al. (2021) and illustrated in Fig. S3, in Europe there are still 87 hotspots with known mining sites, the most important of which are the Idrija mine in Slovenia (Gosar et al. 2016) the Almadén mine in Spain (Millán et al. 2006) and the Monte Amiata (Rimondi et al. 2015). Even in the case of closure of these activities, re-emission of legacy mercury from soil areas surrounding these mining sites, still represent strong localized emission sources of atmospheric GEM (Ferrara et al. 2000;Zhu et al. 2018). Regarding coal combustion in power plants, as reported by the European Union Office, in 2020 there were 166 coal-fired power plants operating in 18 EU countries, with a total capacity of 112 GW (Kapetaki et al. 2021). ...
In the framework of the Italian Special Network for Mercury (ISNM) “Reti Speciali”, a sampling campaign to monitor atmospheric mercury (Hg) was carried out at Monte Sant’Angelo (MSA). This is a coastal monitoring station in the Apulia region, representative of the Southern Adriatic area, within the Mediterranean basin. This work presents continuous Gaseous Elemental Mercury (GEM) measurements over about three years at MSA, using the Lumex RA-915AM mercury analyzer. The aim was to obtain a dataset suitable for the analysis of Hg concentrations in terms of source and transport variation. Diurnal cycles of GEM were evaluated to observe the influence of local atmospheric temperature and wind speed on potential re-emissions from surrounding sea and soil surfaces. Data were also analyzed in terms of long-range transport, using backward trajectory cluster analysis. The spatial distribution of potential sources, contributing to higher measured GEM values, was obtained employing Potential Source Contribution Function (PSCF) statistics. The influence of major Hg anthropogenic point sources, such as mining activities and coal-fuel power plants, both regionally and continentally, from mainland Europe, was observed. The role of the vegetation GEM uptake in modulating the seasonal GEM variability was also investigated. The potential of wildfire influence over the highest detected GEM levels was further examined using active fire data and the evaluation of the vegetation dryness index during the selected episodes.
Graphical abstract
... Mercury in their methylated form is very toxic and bio-accumulative. This heavy metal is found in many anthropogenic activities like municipal waste water discharges, incineration, battery degradation, and seawaters (Ferrara et al. 2000). ...
The appropriate functioning of central nervous system is imperative for its physical integrity and even a slight change in the physicochemical properties leads to permanent neuronal injuries causing cognitive impairments and proteinopathies. Additionally, according to the statistics by WHO, it is expected that the progression of AD is estimated to swell up from 66% to 88% universally by the end of 2050. Epidemiologic studies expose that the foremost cause of neural collapse is the accumulation of heavy metals leading to DNA impairment and distressing the regular functioning of nearly all vital enzymes. Therefore, there exists the urgent prerequisite to alter such oxidative environment which not only limits the impedance of the biochemical processes but also initiates the chronic pathologies. Thus, in this chapter, the authors depict various effects of metal toxicity in human brain and its favorable antidotal strategies in treating the intoxication based on their pharmacological antagonists.KeywordsNeuronal damageAlzheimer’s diseaseReactive oxygen speciesNMDA receptorAntidotal strategy
... The reuse and replacement of steel slag is the alternate solution for preventing environmental pollution by steel industries. In this study, mill scale waste produced in steel companies was recycled to produce valuable products by suitable smelting process using submerged arc furnace and carbonaceous reducing agent (Ferrara et al., 2000). The reductant and fluxing materials were optimized to get hold of dissimilar valuable products. ...
In steel Industry, the manufacturing of steel is coupled with the production of solid waste materials like slag, dust, sludge, etc. Momentous quantities of wastes are generated from steelmaking process which is a spotlight point in recent years. Itsexploitation as well as environmental impact, Mill scale is one of waste materials which are produced as a result of hot undulating of steel in all steel companies. On the other hand, mill scale is painstaking a rich iron resource with least impurities. This paper recapitulates and scrutinizes the generation, composition, characteristics and present status of the employment of the most of the wastes engendered from the steelmaking processes. The alternate solution for avoiding environmental pollution was studied and the usage of steel mill scale in construction is the levelheaded solution was reviewed in numerous research works.The interaction of steel mill scale within the concrete has been methodically investigated. The partial replacement of steel mill scale was examined to explore the various expansions for full amount recycling of solid waste engendered from steel industry, so that the visualization for making "clean & green steel with zero waste" can be attained for endurance and enlargement of steel business in future.
... volcánicos o la actividad geotérmica, las formaciones geológicas con alta concentración de mercurio (depósitos de cinabrio), altas emisiones de intercambio de mercurio elemental entre agua y la atmósfera, la re-emisión de mercurio previamente depositado al suelo y la evasión mediada por las plantas (procesos de evaporación/interfase) y los incendios forestales(Pirrone et al., 2001a, Ferrara et al. , 2000, Gustin et al., 2002, Mason, 2008.La quema de biomasa es un insumo importante y el mercurio de esta fuente es, obviamente, una mezcla de liberación de mercurio debido a los procesos naturales y a la quema inducida por el hombre(Cinnirella and Pirrone, 2006). Recientemente, el conocimiento mejorado del comportamiento de la fuente natural (es decir, las emisiones de los océanos y la vegetación) ha resultado en mejores estimaciones, y estas estimaciones están respaldadas por los resultados actualizados de la literatura.En la Tabla 3 se presenta la información sobre la producción primaria mundial de mercurio registrada desde 1981. ...
... Mercury as a pollutant exists mainly in different forms i.e. metallic element, inorganic salt and as an organic compound with each form possessing toxicity and bioavailability. It has been estimated that the amount of mercury emission into the environment is 2,200 metric tons annually [30]. Both cadmium and mercury pose health hazards in the environment. ...
Information about effectiveness of a wastewater treatment plant is vital in ensuring the quality of water discharged into water bodies and the environment in general meet set standards. In this study, the performance of a wastewater treatment plant located at the Export Processing Zone (EPZ) along River Athi in Machakos County, Kenya was assessed because the final effluent from the treatment plant is released into the river where water is used downstream. Effectiveness of the plant was assessed through the reduction percentage of pollutants between influent and effluent during the dry and wet seasons. Samples of water were collected from the following points i.e. inlet, outflow pool, outlet and along the river. The samples were analyzed for heavy metals, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), organic nitrogen, phosphate, color, temperature, pH, and total coliforms. The resulting data was compared with the established standards. Standard methodologies of laboratory analysis were employed as per Kenyan regulations of 2006 on waste water treatment and discharge. From the results, the waste water treatment plant was not effective in reducing nitrates, phosphates, TDS, TSS, color, and heavy metals i.e. mercury, lead, selenium, copper and cadmium. The inefficiency was more pronounced in rain season. Nitrates (-2.04%), phosphates (-66%), mercury (-48%), lead (-48%), selenium (-2.29%) and copper (-9.75%) were high in the effluent after treatment process during the rains than in the influent. However, the treatment plant was effective in reducing Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). Some parameters like pH, conductivity, temperature, color and TSS were within allowable values described by Kenyan and International standards for effluent discharge into public waters. The study recommends expansion or redesigning of the treatment plant and better monitoring of the sources or types of wastewaters received at the plant for efficient and proper treatment process. Further research required on the seasonal fluctuation of pollutants along River Athi to reduce pollution of the waters. This should be coupled with studying the role of river gradient in self-cleansing of the pollutants.
... Mercury as a pollutant exists mainly in different forms i.e. metallic element, inorganic salt and as an organic compound with each form possessing toxicity and bioavailability. It has been estimated that the amount of mercury emission into the environment is 2,200 metric tons annually [30]. Both cadmium and mercury pose health hazards in the environment. ...
Information about effectiveness of a wastewater treatment plant is vital in ensuring the quality of water discharged into water bodies and the environment in general meet set standards. In this study, the performance of a wastewater treatment plant located at the Export Processing Zone (EPZ) along River Athi in Machakos County, Kenya was assessed because the final effluent from the treatment plant is released into the river where water is used downstream. Effectiveness of the plant was assessed through the reduction percentage of pollutants between influent and effluent during the dry and wet seasons. Samples of water were collected from the following points i.e. inlet, outflow pool, outlet and along the river. The samples were analyzed for heavy metals, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), organic nitrogen, phosphate, color, temperature, pH, and total coliforms. The resulting data was compared with the established standards. Standard methodologies of laboratory analysis were employed as per Kenyan regulations of 2006 on waste water treatment and discharge. From the results, the waste water treatment plant was not effective in reducing nitrates, phosphates, TDS, TSS, color, and heavy metals i.e. mercury, lead, selenium, copper and cadmium. The inefficiency was more pronounced in rain season. Nitrates (-2.04%), phosphates (-66%), mercury (-48%), lead (-48%), selenium (-2.29%) and copper (-9.75%) were high in the effluent after treatment process during the rains than in the influent. However, the treatment plant was effective in reducing Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). Some parameters like pH, conductivity, temperature, color and TSS were within allowable values described by Kenyan and International standards for effluent discharge into public waters. The study recommends expansion or redesigning of the treatment plant and better monitoring of the sources or types of wastewaters received at the plant for efficient and proper treatment process. Further research required on the seasonal fluctuation of pollutants along River Athi to reduce pollution of the waters. This should be coupled with studying the role of river gradient in self-cleansing of the pollutants.
... Due to its higher volatility, it is very common to get poisoned by mercury vapor also. Ferrara et al. have estimated that about 2200 t of mercury per annum is released to the environment from different sources (Ferrara et al. 2000). The volcanic eruption, leaching of mercury-containing ores, mining and metallurgical processes, and burning of fossil fuels like coal, natural gas, or oil are also the major contributors for mercury contamination to the environment. ...
Alarmingly large amounts of wastes with diversified composition and physicochemical properties are produced regularly by various anthropogenic activities. The accumulation of large quantity of wastes with severe toxic properties is becoming a threat for the healthy environment of the earth. Due to diversified compositions and properties, the management of such waste is complex and requires a high degree of fundamental and technological understanding for a viable treatment and post-treatment procedure. The growing concerns for the environment and consequences of the hazardous pollutants have attracted serious research attention to manage the waste and to mitigate the accompanying toxic pollutants. In this chapter, an overview of various wastes and pollutants regularly added to the environment and a current scenario for their management are presented. This chapter also discusses the mitigation of toxic pollutants of varying origin with a specific focus on the research methodologies developed toward this.
... Salt-marsh plants, such as Halimione portulacoides that exists in our sampling area, enhance the vegetation-air Hg 0 fluxes during daylight [43]. A daily trend was observed in [35], where the nighttime GEM evasion fluxes were 2 to 5-fold lower than those of the daytime, probably due to the lack of solar radiation that affects the release of elemental mercury from surface water during daytime. The negative sign in some cases is due to transported elemental mercury from other places. ...
Coastal rural areas can be a source of elemental mercury, but the potential influence of their topographic and climatic particularities on gaseous elemental mercury (GEM) fluxes have not been investigated extensively. In this study, gaseous elemental mercury was measured over Mediterranean coastal grassland located in Northern Greece from 2014 to 2015 and GEM fluxes were evaluated utilizing Monin–Obukhov similarity theory. The GEM fluxes ranged from –50.30 to 109.69 ng m−2 h−1 with a mean value equal to 10.50 ± 19.14 ng m−2 h−1. Concerning the peak events, with high positive and low negative GEM fluxes, those were recorded from the morning until the evening. Rain events were a strong contributing factor for enhanced GEM fluxes. The enhanced turbulent mixing under daytime unstable conditions led to greater evasion and positive GEM fluxes, while, during nighttime periods, the GEM evasion is lower, indicating the effect of atmospheric stability on GEM fluxes. The coastal grassland with its specific characteristics influences the GEM fluxes and this area could be characterized as a source of elemental mercury. This study is one of the rare efforts in the research community to estimate GEM fluxes in a coastal natural site based on aerodynamic gradient method.
... Hence detailed knowledge/information of heavy metals is rather significant for allowing appropriate defensive measures against their excessive contact with human body (Ferrara 2000). ...
The contamination chain of heavy metals almost always follows cyclic order in the environment as industry, atmosphere, soil, water, foods and human. As it is clear that chronic exposure to heavy metals and metalloids at low levels cause the adverse effects. Heavy metals have been proved to be toxic to human and environmental health. Heavy metal toxicity is regarded as major threat and there is several health risks associated with it. Sometimes they may act as pseudo elements of the body but event at certain times they may interfere with metabolic processes. Few metals, like aluminum, can be removed by elimination activities, while some of the metals get accumulated in the body and food chain, exhibiting a chronic nature. Different public health procedures have been taken to control, prevent and treat metal toxicity which occurs at various levels, such as occupational exposure and environmental factors. Metal toxicity depends on the dose absorbed, route of exposure and duration of the exposure, which can lead to different disorders and results in excessive damage due to oxidative stress induced by free radical formation. This review provides insight into the sources of heavy metals and their harmful effects on environment and living organisms.
... Major sources of mercury pollution include oil and gas industries, agriculture, mining, discharges of industrial wastewater and waste incinerations . The annual level of Hg emission into the environment has been estimated at 2200 metric tons (Ferrara et al., 2000). Mercury has the ability to damage the protein structures altering by this way the plant cellular structure (Jaishankar et al., 2014). ...
... The values of PBM recorded were lower than MDL because there were a major concentration of coarse particulate emitted by volcanos, so Hg could be associated to it. There are currently many difficulties in quantifying the Hg flux from volcanic emissions due to the spatial and temporal variability in the activity from one volcano to another (Ferrara et al., 2000;Bagnato et al., 2011), or from different emission points on the volcano (Bagnato et al., 2007). Due to the logistical restrictions of acquiring measurements at volcanos (difficulty of access, limited power supply, etc.), Hg measurements often only comprise few data points and the related Hg emission current estimates show a large variability which partly reflects the complexity of the chemical and physical processes that Hg undergoes while interacting with the atmosphere. ...
In the framework of the ongoing MEDOCEANOR measurements program, an oceanographic cruise campaign was carried out during summer 2015 in the Western sector of Mediterranean Sea basin, on-board the research
vessel ”Minerva Uno” of the Italian National Research Council (CNR). The overall goal was to investigate the
dynamic patterns of mercury in the Marine Boundary Layer (MBL) and the main factors affecting mercury
behaviour at both coastal and offshore locations. The mean concentrations of the recorded Hg species were 1.6 ±0.5 ngm−3, 11.8 ± 15.0 pgm−3, and 2.4 ± 1.1 pgm−3, respectively for GEM, GOM, and PBM. Moreover, during the measurement period typical fair-weather conditions of the Mediterranean summer were encountered with high levels of solar radiation and temperature that favoured photochemical reactions. Atmospheric pollutants such as ozone, sulphur oxides and nitrogen oxides and other meteorological parameters were in addition recorded and jointly discussed with selected mercury events in terms of their spatio-temporal variations. Changes in air pollutant concentrations were also argued in the light of their likely influencing sources, among which, anthropogenic activities, such as the mercury cell chlor-alkali complex in Tuscany, Italy, and natural influence, like volcanic ashes, detected around the Aeolian area and the in-situ production of reactive gaseous mercury within the Marine Boundary Layer.
... Air-sea mercury flux is mainly driven by the concentration gradient and meteorological conditions (Gårdfeldt et al., 2001;Gårdfeldt et al., 2003;Wängberg et al., 2001). For instance, elevated DGM values and strong winds would result in higher fluxes (Fig. 4, b and c), as higher wind causes more breaking waves, subsequently extending the area of water surface and the bubbles and increasing the air-water exchange (Ferrara et al., 2000). Nevertheless, the generally positive air-sea flux indicated that the East Southern Ocean is a net source for GEM in the summer. ...
Gaseous elemental mercury (GEM) in the marine boundary layer (MBL), and dissolved gaseous mercury (DGM) in surface seawater of the Southern Ocean were measured in the austral summer from December 13, 2014 to February 1, 2015. GEM concentrations in the MBL ranged from 0.4 to 1.9 ng m− 3 (mean ± standard deviation: 0.9 ± 0.2 ng m− 3), whereas DGM concentrations in surface seawater ranged from 7.0 to 75.9 pg L− 1 (mean ± standard deviation: 23.7 ± 13.2 pg L− 1). The occasionally observed low GEM in the MBL suggested either the occurrence of atmospheric mercury depletion in summer, or the transport of GEM-depleted air from the Antarctic Plateau. Elevated GEM concentrations in the MBL and DGM concentrations in surface seawater were consistently observed in the ice-covered region of the Ross Sea implying the influence of the sea ice environment. Diminishing sea ice could cause more mercury evasion from the ocean to the air. Using the thin film gas exchange model, the air-sea fluxes of gaseous mercury in non-ice-covered area during the study period were estimated to range from 0.0 to 6.5 ng m− 2 h− 1 with a mean value of 1.5 ± 1.8 ng m− 2 h− 1, revealing GEM (re-)emission from the East Southern Ocean in summer.
... If we extend our calculations over the entire submarine degassing area of Panarea Island (~2.3 km 2 ), we obtain a total Hg 0 evasion flux of about 0.0001 t y − 1 . Compared to a general overview of the results provided in the literature, this value accounts for a slight proportion of the total Hg flux released annually into the atmosphere from the entire Mediterranean Basin, accounting for 60-77 t y − 1 (Andersson et al., 2007;Gardfeldt et al., 2003;Ferrara et al., 2000). Despite this, however, this study provides new important information with which to expand the currently limited database on Hg released from submarine hydrothermal activity, and allows some inferences to be made regarding the quality of previous estimates of mass balance for the Mediterranean Sea. ...
There is a growing concern about the mercury (Hg) vented from submarine hydrothermal fluids to the marine surrounding and exchange of dissolved gaseous mercury (DGM) between the sea surface and the atmosphere. A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out in 2015 (15–17th June and 17–18th November), in order to investigate the concentration of Hg species in hydrothermal fluids and the vertical distribution in the overlying water column close to the submarine exhalative area. Specific sampling methods were employed by Scuba divers at five submarine vents located along the main regional tectonic lines. The analysis of the hydrothermal fluids indicates a site-to-site variation, with filtered total mercury (FTHg) concentrations ranging from 1072 to 4711 pM, as a consequence of the gas bubbles partial dissolution. These results are three orders of magnitude higher than the FTHg concentrations found in the overlying seawater column (ranging from 5.3 to 6.3 pM in the mid waters), where the efficient currents and vertical mixing result in more dilution, and potentially rapid transfer of the dissolved gaseous Hg to the atmosphere. Dissolved gaseous mercury (DGM) and gaseous elemental mercury (GEM) were simultaneously measured and combined in a gas-exchange model to calculate the sea-air Hg⁰ evasional flux. Based on the data of DGM (range: 0.05–0.22 pM) and atmospheric GEM (range: 1.7 ± 0.35–6.4 ± 2.6 ng m− 3), we argue that the surface seawater off Panarea is mostly supersaturated in dissolved elemental gaseous mercury compared to the atmosphere, with a sea-air Hg⁰ net flux ranging from 0.7 to 9.1 ng m⁻² h− 1 (average: ~ 4.5 ± 3.5 ng m⁻² h− 1). Since the empirical gas-exchange model does not include the contribution of Hg⁰ released as gas bubbles rising from the vents toward sea-surface, the calculated Hg⁰ evasional flux for this location is most likely larger.
... The highest Hg SPM values were obtained at the Gdynia-Oksywie site, located 2.5 km away from the shoreline (median: 26.3 ng g −1 ), the second highest at the Vistula mouth site, 5 km away from the shoreline (median: 20.3 ng g −1 ) and the third highest at the central gulf site, 18 km away from the shoreline (median: 18.5 ng g −1 ). A similar correlation was observed in studies conducted in previous years in the Gulf of Gdańsk (Saniewska et al., 2010;Saniewska et al., 2014a) and the Mediterranean Sea (Ferrara et al., 2000). This is because the 'dilution' of the Hg-rich material washed off from land as it becomes dispersed in the basin. ...
... No significant seasonal variation in the western Mediterranean Sea can be confirmed from literature values presented in Table 2. TGM was observed in a study by Kotnik et al. (2014) to show a seasonal trend where the highest average concentration in the Mediterranean Region (Spain, Italy, Turkey, Israel, 1998 was measured during winter (3.38 ng m − 3 ) and the lowest in autumn (1.86 ng m − 3 ). Ferrara et al. (2000b) found a seasonal variation in mercury evasion from the Mediterranean Sea with the highest rates observed during summer and lowest during winter. Seasonal and spatial variations of DGM concentrations and mercury evasion in the Mediterranean Sea were also observed by Kotnik et al. (2014). ...
Continuous measurements of gaseous elemental mercury (GEM) in air and dissolved gaseous mercury (DGM) in surface seawater were performed during two oceanographic campaigns (Fenice 2011 (25/10–11/11) and Fenice 2012 (11–29/8)), carried out in the Tyrrhenian Sea (Fenice 211), western Mediterranean Sea and the Atlantic Ocean (Fenice 2012) as part of the GMOS project (Global Mercury Observation System). Measured GEM and DGM were used to estimate the air-sea exchange of elemental mercury by using a two-thin film gas exchange model.
... At national levels, there have been and are various research initiatives addressing several aspects of mercury pollution problems at contaminated sites in Europe including abandoned mercury mines and surrounding areas (i.e., Almaden, Spain) (Ferrara et al., 1997(Ferrara et al., , 1998, volcanoes (i.e., Etna, Stromboli) (Edner et al., 1992;Ferrara et al., 2000b), remote areas Sprovieri and Pirrone, 2000a), and surface and deep waters of rivers, lakes, coastal zones and the open sea Cossa et al., 1996;Covelli et al., 1999;Horvat et al., 1999;Ferrara et al., 2000a). Within the framework of the MED-OCEANOR project funded by the Italian National Research Council (CNR) an in-depth investigation was carried out in the Summer of 2000 by a group of research institutes to quantify and possibly explain spatial and temporal patterns of mercury and its species concentrations in air, surface and deep water samples, and gaseous mercury exchange rates at the air-water interface along the path of a 6000 km cruise route around Mediterranean Sea. ...
... Over the last two decades, Hg biogeochemistry in coastal marine environments is receiving increasing attention Ferrara et al. 2000;Lanzillotta et al. 2002;Gårdfeldt et al. 2003;Rolfhus and Fitzgerald 2004;Andersson et al. 2007;Fantozzi et al. 2007;Ci et al. 2011a, c). Due to its unique physicochemical properties, the coastal marine ecosystem is considered as an important reactor for rapid, significant, and complicated biogeochemistry of Hg (Fitzgerald et al. 2007). ...
The air–sea exchange of gaseous mercury (mainly Hg(0)) in the tropical ocean is an important part of the global Hg biogeochemical cycle, but the related investigations are limited. In this study, we simultaneously measured Hg(0) concentrations in surface waters and overlaying air in the tropical coast (Luhuitou fringing reef) of the South China Sea (SCS), Hainan Island, China, for 13 days on January–February 2015. The purpose of this study was to explore the temporal variation of Hg(0) concentrations in air and surface waters, estimate the air–sea Hg(0) flux, and reveal their influencing factors in the tropical coastal environment. The mean concentrations (±SD) of Hg(0) in air and total Hg (THg) in waters were 2.34 ± 0.26 ng m−3 and 1.40 ± 0.48 ng L−1, respectively. Both Hg(0) concentrations in waters (53.7 ± 18.8 pg L−1) and Hg(0)/THg ratios (3.8 %) in this study were significantly higher than those of the open water of the SCS in winter. Hg(0) in waters usually exhibited a clear diurnal variation with increased concentrations in daytime and decreased concentrations in nighttime, especially in cloudless days with low wind speed. Linear regression analysis suggested that Hg(0) concentrations in waters were positively and significantly correlated to the photosynthetically active radiation (PAR) (R
2 = 0.42, p < 0.001). Surface waters were always supersaturated with Hg(0) compared to air (the degree of saturation, 2.46 to 13.87), indicating that the surface water was one of the atmospheric Hg(0) sources. The air–sea Hg(0) fluxes were estimated to be 1.73 ± 1.25 ng m−2 h−1 with a large range between 0.01 and 6.06 ng m−2 h−1. The high variation of Hg(0) fluxes was mainly attributed to the greatly temporal variation of wind speed.
... 56 The Hg cycle has been widely perturbed by human activities (Fitzgerald et al.,, 2007;Lamborg et 57 al.,, 2014), and the anthropogenic component of Hg in the atmosphere is currently around 30% 58 (Pirrone et al.,, 2010). However, Hg evasion from the sea surface will still remain an important 59 source of Hg in the atmosphere for a long period of time, because of the quantity of the Hg legacy 60 and the size of the reservoir (Ferrara et al.,, 2000a). In particular, the Atlantic Ocean and 61 European seas have an influence on atmospheric Hg concentrations in the European troposphere, 62 especially at coastal sites. ...
Total gaseous mercury (TGM) was continuously measured in 2009 and 2012, at a coastal site on the Mediterranean Sea (La Seyne-sur-Mer, France). Air temperature, humidity, wind speed and direction, and chemical parameters (O3, CO, NOX and PM10) were also measured as tracers of atmospheric pollution. Average TGM concentrations did not differ between the two years, 2.20 ± 0.54 and 2.16 ± 0.60 ng.m-3 for 2009 and 2012 respectively. Diurnal variations of TGM were observed for both years and linked to local industrial or urban activities. Furthermore, a clear seasonal trend was observed, with TGM minima in summer and maxima in winter. This seasonality is common to several air pollutants, like the result of the variation in the dispersion of pollutants in the boundary layer and higher photochemical activity in summer. The highest TGM concentrations (>3ng.m-3) were associated with air masses originating over urban and industrial areas of the Rhône Valley and local/regional anthropogenic sources. The influence of polluted air masses from these local/regional sources was confirmed by the significantly positive correlations between TGM and CO, NOx and PM10. We demonstrate that polluted air masses from nearby urban and industrial regions are an important source of TGM to Mediterranean coastal areas, rather than volatilization from the sea surface.
... Methylmercury is a neurotoxic compound which is responsible for microtubule destruction, mitochondrial damage, lipid peroxidation and accumulation of neurotoxic molecules such as serotonin, aspartate, and glutamate (Patrick, 2002). The total amount of mercury emission into the environment has been assessed at 2,200 metric tons annually (Ferrara et al., 2000). It is estimated that 8 to 10% of American women have mercury levels that would induce neurological disorders in any child they gave birth to, according to both the Environmental Protection Agency and National Academy of Science (Haley, 2005). ...
Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning. They sometimes act as a pseudo element of the body while at certain times they may even interfere with metabolic processes. Few metals, such as aluminium, can be removed through elimination activities, while some metals get accumulated in the body and food chain, exhibiting a chronic nature. Various public health measures have been undertaken to control, prevent and treat metal toxicity occurring at various levels, such as occupational exposure, accidents and environmental factors. Metal toxicity depends upon the absorbed dose, the route of exposure and duration of exposure, i.e. acute or chronic. This can lead to various disorders and can also result in excessive damage due to oxidative stress induced by free radical formation. This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.
Plain Language Summary
Volcanism is widely recognized as the most important natural source of mercury (Hg) globally, but existing emissions estimates contain substantial uncertainty. This study combines satellite observations of sulfur dioxide (SO2) in volcanic plumes and measured Hg:SO2 ratios to quantify the magnitude and spatiotemporal variability of global volcanic Hg emissions. Using a global model, we show that the spatial pattern of volcanic releases and atmospheric dynamics result in greater concentrations of volcanic Hg in the mid‐latitude Northern Hemisphere compared to the mid‐latitude Southern Hemisphere. Modeling results suggest that variability in volcanic Hg emissions at some locations may obscure trends in atmospheric Hg concentrations driven by human emissions. The influence of volcanic Hg emissions should therefore be considered during selection of global monitoring sites used to track the progress of regulatory actions designed to mitigate Hg pollution. Volcanic release estimates from this work suggest the natural atmospheric Hg reservoir was ∼7 times smaller than in 2015, reinforcing that humans have profoundly disrupted the global biogeochemical Hg cycle.
Heavy metals are natural components of the Earth"s crust. They cannot be degraded or destroyed. Eight common heavy metals are discussed in this brief: arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. Even these metals do not have any biological role, they remain present in our body harms human body and its functioning. As all ayurvedic formulation contains large amount of heavy metals due to the herbal ingredients used for preparation. One of the ayurvedic formulation from among formulation i.e. Shankh-vati tablet. We have studied the amount of heavy metals present in shankh-vati tablet. Shankh-vati is and ayurvedic classical formulation available in tablet form which is used to manage the digestive disorders. It is also used to resolve the various problems like anorexia, vomiting, gastritis etc. Natural ingredients used in this medicine help to balance the tridoshas in body. Shankh-vati totally contains 15ingredients. Mainly parad (mercury) is mostly used in ayurvedic formulation. Mercury is present in large amount in ayurvedic formulation. Along with determination of heavy metals, limit test for iron and sulfate is also done. Sulfate occur as microscopic particles(aerosols) resulting from fossil fuel and biomass combustion. They increase the acidity of the atmosphere and form acid rain. The limit test has passed which confirms that heavy metals in shankh-vati tablet is in limit. Also other metals like iron and sulfate are in limit.
There are many questions regarding the behavior of mercury in the sea-atmosphere system of the northwestern Pacific. Continuous underway measurements of atmospheric gaseous elemental mercury (GEM) and measurements of sea-air GEM evasion fluxes were carried out in the marginal seas of northwestern Pacific from the South China Sea to the Sea of Okhotsk in fall-winter 2019. The median GEM concentration (1.1 ng/m³) was lower than both the background value and the averages previously observed in these areas. A latitudinal gradient of atmospheric GEM and GEM evasion fluxes with maximum values at southern latitudes was found. The following areas have been identified as potential source areas: the Kurill area of the Pacific Ocean Northeast China, Korean Peninsula, and the territory from the southwest coast of the Yellow Sea to the south of Indochina. Seasonal variations were observed in the Sea of Japan and East China Sea with higher GEM concentrations in winter than in fall. Our data and analysis of published data showed significant relationships between GEM evasion fluxes, latitude and sea surface temperature (SST). It seems that on a global scale, along with the GEM gradient between water and atmosphere, SST is the most significant parameter for sea-air GEM evasion fluxes.
Abstract Background Chrysichthys nigrodigitatus (CN) and Oreochromis niloticus (ON) health status were investigated in Asejire Reservoir (AR) and Lagos Lagoon (LL), South-west Nigeria. Fish samples collected were separated into sexes. Growth pattern {length (cm); weight (g), Isometric index, condition factor (K)} were measured. Heavy metals (lead (Pb), iron (Fe), zinc (Zn), copper (Cu), and chromium (Cr) in ppm concentrations were determined in Lagos Lagoon and Asejire reservoir. Results Fish samples ranged at one male to one or two females. No significant difference in length and weight of O. niloticus between locations. Significant difference in weight occurred in C. nigrodigitatus between locations; highest condition factor was recorded in Asejire Reservoir O. niloticus, (ARON); lowest condition factor was observed in Asejire Reservoir C. nigrodigitatus (ARCN) as this indicated a negative allometric value, normal in Bagridae species. Male species possessed higher condition (K)—factor than female species within locations, between locations, between species, and within species, female C. nigrodigitatus having higher condition factor than male ARCN. Highest isometric value occurred in ARON and lowest in Lagos Lagoon C. nigrodigitatus (LLCN). Male ARON had highest isometric value, and O. niloticus species had higher isometric value (b ≤ 3) and positive allometric (b > 3); and C. nigrodigitatus has negative allometric (b
Kesehatan dan lingkungan hidup memiliki hubungan erat, terutama dalam penggunaan logam berat dengan benar atau pun adanya penyalahgunaan pemakaian pada produk/sediaan baik makanan serta kosmetik. Logam berat seperti merkuri (Hg), timbal (Pb), cadmium (Cd), arsenik (As) dan tembaga (Cu) seringkali memiliki nilai diatas batas ambang untuk kesehatan manusia. Hal ini akan berdampak buruk terhadap kehidupan kita, terlebih jika kita membutuhkan produk dalam jangka waktu lama dan terus-menerus sehingga terakumulasi baik di kulit ataupun organ tubuh lainnya. Akhir-akhir ini banyak penyakit baru yang muncul dan ditemukan, ada kemungkinan salah satu penyebabnya adalah masuknya logam berat ke dalam tubuh kita sedikit demi sedikit secara berulang dalam waktu cukup lama. Hal ini tidak akan menjadi masalah bila benteng ketahanan tubuh kita cukup baik dan pola hidup sehat dilakukan seimbang bersamaan dengan konsumsi antioksidan alami optimal. Oleh sebab itu kami sebagai profesi di bidang kesehatan yaitu dosen dari Fakultas Farmasi serta Sekolah Vokasi-UGM juga Ibu Guru, terpanggil untuk menuliskan tentang efek negatif logam berat terhadap kesehatan kita. Selain itu, semoga masyarakat pada umumnya, termasuk mahasiswa memperoleh informasi dengan baik. Tentu saja penulisan buku ini jauh dari sempurna dan membutuhkan masukan serta kritisi dari semua pembaca. Akhir kata, kami bersyukur pada Allah SWT atas selesainya penulisan buku ini dan mengucapkan banyak terimakasih kepada semua pihak yang punya andil dalam penulisan buku ini khususnya Bapak Prof. Dr.Agung Endro Nugroho, M.Sc., Apt., Frau Prof. Dr. Ulrike Holzgrabe di Universitas Wuerzburg dan Deutscher Akademischer Austausch Dienst (DAAD)-Jerman. Yogyakarta, 17 Januari 2017 Tim Penulis
Dissolved gaseous mercury (DGM) was measured continuously using two newly developed techniques and a manual technique. The continuous techniques were based on the equilibrium between the aqueous and gaseous phase (DGM = Hgextr / H', Hgextr is the measured mercury concentration in the gas phase, H' is the Henry's Law coefficient at the desired temperature). In order to calculate the annual mercury evasion from the Mediterranean Sea, diurnal and seasonal measurements of DGM, total gaseous mercury in air (TGM), water temperature and wind speed were performed. During August 2003, March–April 2004 and October–November 2004 measurements of these parameters were conducted on board the RV Urania. The continuous measurements of DGM showed a diurnal variation in concentration, at both coastal and off shore sites, with higher concentrations during daytime than nighttime. The concentration difference could be as large as 130 fM between day and night. The degree of saturation was calculated directly from the measurements, S = Hgextr / TGM and was found to vary between the different seasons. The highest average degree of saturation (850%) and the largest variation in saturation (600–1150%) was observed during the summer. The spring showed the lowest variation (260–360%) and the lowest average degree of saturation (320%). The autumn also showed a large variation in saturation (500–1070%) but a lower average (740%) compared to the summer cruise. This might be explained by the temperature difference between the different seasons, since that parameter varied the most. The flux from the sea surface was calculated using the gas exchange model developed by Nightingale et al. [Nightingale, P.D., Malin, G., Law, C.S., Watson, A.J., Liss, P.S., Liddicoat, M.I., Boutin, J., Upstill-Goddard, R. C., 2000. In situ evaluation of air–sea gas exchange parameterization using novel conservative and volatile tracers. Global Biogeochemical Cycles, 14(1):373–387]. The evasion varied between the different seasons with the highest evasion during the autumn, 24.6 pmol m− 2 h− 1. The summer value was estimated to 22.3 pmol m− 2 h− 1 and the spring to 7.6 pmol m− 2 h− 1. Using this data the yearly evasion from the Mediterranean Sea surface was estimated to 77 tons.
This study was aimed to investigate liver function of Wistar rats influenced by oral ingestion of different doses of combination of benzo-ic and citric acids as food additives. Administered doses were (100, 500 and 1250 mg/kg b.w). Rats' serum GGT and ALP were used as an indicators. Forty four Wistar rats were divided into four groups’ eleven rats in each group, six males and five females. One group was put as control, and the remainder of the three groups received different doses of combination of benzoic and citric acids. Housing in Meck Nimir research center Khartoum. They were recived free tab water and prepared food systems liberally. Serum was taken from each rats and analyzed by spectrophotometer. Transverse sections of liver organs were used to prepare Histopathiological slides. A sig-nificant (p ≤ 0.05) gradual increase according to increased treatment doses in serum GGT and alkaline phosphatase were observed in treated animals, compared with control. Also there were different signs of liver histopathological changes including plate hyperaemia, hemorhage, haemosiderosis,diffuse coagulative necrosis ,cytoplasmic vacuolation and sinusoidal dilatation. Change in nuclei. Compared to control all tested animals showed significant (p ≤ 0.05) inccreased body weight. All animals survived till the end of the experiment. We concluded that oral ingestion of combination of benzoic and citric acid causes liver malfunction, so it is preferred to ingest foods and beverages containing combination of benzoic and citric acid with caution. This study was aimed to investigate rats’ liver malfunction induced by oral ingestion of combination of benzoic with citric acid in ratio (1:1/ v: v).
Dissolved gaseous mercury (DGM) was studied in surface and deep waters of the Mediterranean Sea over the last 15 years during several oceanographic cruises on board the Italian research vessels Urania and Minerva Uno, covering the Western and Eastern Mediterranean Basins as well as Adriatic Sea as its northernmost part. DGM was measured together with other mercury species (RHg - reactive Hg, THg - total Hg, MeHg - monomethyl Hg and DMeHg - dimethylmercury), and with water quality parameters in coastal and open sea deep water profiles. DGM represents a considerable portion of THg (on average 20%) in Mediterranean waters. Spatial and seasonal variations of measured DGM concentrations were observed in different identified water masses. DGM was the highest in the northern Adriatic, the most polluted part of the Mediterranean Sea as a consequence of Hg mining in Idrija and heavy industry in northern Italy, and near the Gulf of Lion. Generally, average DGM concentration was higher in the West and East Mediterranean Deep Waters (WMDW and EMDW) and Levantine Intermediate Water (LIW) than in overlaying Modified Atlantic Water (MAW); however, it was the highest in N Adriatic Surface waters (NAdSW) and consequently in outflowing Adriatic Deep Waters (AdDW). In deep water profiles the portion of DGM typically increased at depths with oxygen minimum and then towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea), indicating its bacterial and/or geotectonic origin. During oceanographic cruises in 2011 and 2015 in the Tyrrhenian Sea, novel methods for continuous DGM determination in surface waters (Wangberg and Gardfeldt, 2011, Begu et al., 2016) were applied and compared to the standard method, and showed good agreement.
As part of a monitoring programme conducted by the Institute of Environment and Development (IDAD) and supported by the regional municipal solid waste (MSW) management authorities, an extensive database of trace metals (TMs) concentrations in ambient air was collected in two sites, Leça do Balio (LB) and Vila Nova da Telha (VNT), located in Porto's metropolitan area, north of Portugal. Since 2004, concentrations of As, Cd, Pb, Cu, Cr, Mn, Hg, Ni and Zn were measured in PM10. In addition, total gaseous mercury (TGM) was monitored since 2008. These measurements were used to assess long-term trends of concentrations. Statistical analysis was used to search for the possible origin of the TMs.
During the monitoring period, the mean TMs concentrations followed the order: Zn > Cu > Pb > Mn > Cr > Ni > As ≈ Hg > Cd, and have not exceeded the current air quality guidelines values. Concentrations of As, Cd, Pb, Mn, and Hg have slightly decreased during the measurement period despite already being at historically low levels. The concentrations range of Zn, Cd, Pb and As suggests a seasonal variability for these elements in ambient air, for both sites. Average TGM levels were 1.93 and 1.35 ng m⁻³, for LB and VNT respectively. In terms of seasonality, a statistical difference was found in TGM concentrations between winter and summer for LB. A daily pattern was also observed in TGM with minimum concentrations during the night and early morning.
The use of mercury in manufacturing and medical purposes has been recorded since classical times in China, Egypt, Greece, and Rome. Concomitantly, poisoning by this metal has also been reported since 2,000 years ago, such as in Pliny the Elder’s (23–79 AD) Naturae Historiarum Libri, which refers to cinnabar (HgS) poisoning among miners at Almaden, Spain (Rackham 1952). Mercury as a poison has been documented for many centuries.
Methylmercury, a pollutant produced by various industrial activities, is a potent neurotoxin that has now caused serious contamination issues within our oceans. As a fat-soluble molecule, methylmercury enters the food chain and accumulates in the flesh of the fish that then may end up in our supermarkets. Consuming larger, longer living fish on a regular basis is now known to pose a serious health hazard, especially for children and pregnant women who are consequently advised to limit (or even avoid) the intake of some species such as fresh tuna or marlin.
Heavy metals are more widespread around the world and dangerous for biosphere because they cannot be degraded or destroyed rather tend to be bioaccumulated. Plants can survive even in the extreme environmental conditions, but some environmental factors can affect its various growth aspects and hence the plant productivity. The problem of heavy metal toxicity is further aggravated by the persistence of the metals in the environment. Toxic heavy metals entering the plant tissues inhibit most physiological processes at all levels of metabolism. The extent of inhibition of photosynthesis, ion water uptake, and nitrate assimilation is greatly dependent on the concentration of the metal ions, sensitivity, and tolerance of the plant. There is, therefore, a pressing need to deal with the problem of excess metal already present in the soil and to prevent future contamination.
A mass balance budget for mercury at Ocean margins is proposed on the basis of recent data on exchange fluxes with terrestrial, atmospheric and marine reservoirs. The largest single mercury flux consists of particulate species from rivers (~5 Mmol a-1), which is, primarily, unreactive and quickly buried in nearshore sediments. The most important source of mobile mercury for ocean margins is the atmosphere directly via deposition and indirectly via upwellings (total ≈ 5 Mmol a-1). The direct atmospheric input to coastal zones rivers (~2 Mmol a-1), exceeds considerably the dissolved inputs from rivers (~0.13 Mmol a-1). The evasion of elemental mercury from coastal surface waters is balanced by the mercury deposition from the atmosphere, but geographical differences exist suggesting a net mercury transfert to the higher latitudes. The overall residence time for mercury on the continental shelves is about 4 months. This is less than the mean residence time of water on the shelves (~1.3 year) and confirms the known reactivity of mercury in aquatic environments. However, two fractions of mercury are actively recycled (through the atmosphere and through the organic carbon recycling). The highly productive zones associated with frontal stuctures near the shelf edges appear to be very active in redistributing mercury species between ocean and coastal areas. One consequence is that the main source of methylmercury for coastal waters is upwelled oceanic waters.
Mercury content and speciation were determined in freshwater zooplankton from twelve northern Wisconsin (USA) lakes that spanned gradients of dissolved organic carbon (DOC, 1.6 to 20.9 mg/L) and pH (4.6 to 7.2). MeHg in crustacean taxa ranged from 1 to 479 ng/g dry weight, and from 2 to 45 ng/g in the invertebrate predators. Total Hg in the predators ranged from 20 to 153 ng/g. Although the highest MeHg values were found in the herbivores from high DOC lakes (and the experimentally acidified basin of Little Rock Lake), we observed considerable variation in the relationship between MeHg content of zooplankton and lakewater DOC. Bioconcentration factors (BCF) for both MeHg (3.5 to 7.1 log units) and Hg (3.7 to 5.4 log units) decreased with increasing lake DOC, while pH effects were not as apparent. Bioconcentration of MeHg was higher than Hg indicating that MeHg increases while non-methyl Hg declines in progressively higher trophic levels. Biomagnification factors (BMF) for Hg and MeHg were low relative to BCF. The BMF for crustaceans averaged 0.4 log units for MeHg and –0.5 log units for Hg, indicating that MeHg increased 2.5-fold from seston to crustacean herbivores, while non-MeHg concentrations declined. Unlike BCF, BMF were not related to DOC or pH. In contrast to studies of vertebrate predators, both BCF and BMF in the invertebrate predatorChaoborus, were lower than those in presumed prey. These observations point toward several complexities in the transport of Hg species in the lower levels of aquatic foodwebs.
From 1992 till 1994 sampling campaigns were carried out in the Scheldt estuary the year round, in order to assess the behaviour of the various Hg species. On the basis of these data annual and seasonal budgets were calculated for particulate Hg, total dissolved Hg and dissolved methylmercury. These budgets allow evaluation of the consistency of each individual flux or process such as the inputs of the various Hg species into the North Sea, the sedimentation flux of particulate Hg in the area of high turbidity, the evasional fluxes, the formation rates of Hg°, etc. in relation to the other ones.
Gas transfer across the air-sea interface may be conveniently treated in terms of a two layer model that separates gas and liquid phase resistances. Fluxes of gases into water increase gradually with wind velocity up to about 8 m/s. At higher wind velocities the transfer rates increase more rapidly. The air-sea transfer of hydrogen, formaldehyde, methane, the carbon oxides, the nitrogen oxides, oxygen and some sulphur and halogen compounds are discussed in detail.-P.BrimblecombeSchool of Environ Sciences, Univ of East Anglia, Norwich, NR4 7TJ, UK.
The role of biological activities in the reduction and volatilization of Hg(II) from a polluted pond was investigated. Elemental mercury was evolved from pond water immediately following spiking with(203)Hg(NO3)2, whereas an acclimation period of 36 hours was required in control samples collected from a nearby, unpolluted river before onset of volatilization. Genes encoding the bacterial mercuric reductase enzyme (mer genes) were abundant in DNA fractions extracted from biomass of the pond microbial community, but not in samples extracted from control communities. Thus, evolution of Hg(0) was probably due to activities mediated by the bacterial mercuric reductase. Of four characterizedmer operons, the system encoded by transposon 501 (mer(Tn501)) dominated and likely contributed to the majority of the observed Hg(II) volatilization. Thus,mer-mediated reduction and volatilization could be used to reduce Hg(II) concentrations in polluted waters, in turn decreasing rates of methylmercury formation by limiting substrate availability.
The concentrations of total gaseous mercury (TGM) in air over the southern Baltic Sea and dissolved gaseous mercury (DGM) in the surface seawater were measured during summer and winter. The summer expedition was performed on 02–15 July 1997, and the winter expedition on 02–15 March 1998. Average TGM and DGM values obtained were 1.70 and 17.6ngm−3 in the summer and 1.39 and 17.4ngm−3 in the winter, respectively. Based on the TGM and DGM data, surface water saturation and air-water fluxes were calculated. The results indicate that the seawater was supersaturated with gaseous mercury during both seasons, with the highest values occurring in the summer. Flux estimates were made using the thin film gas-exchange model. The average Hg fluxes obtained for the summer and winter measurements were 38 and 20ngm−2d−1, respectively. The annual mercury flux from this area was estimated by a combination of the TGM and DGM data with monthly average water temperatures and wind velocities, resulting in an annual flux of 9.5μgm−2yr−1. This flux is of the same order of magnitude as the average wet deposition input of mercury in this area. This indicates that reemissions from the water surface need to be considered when making mass-balance estimates of mercury in the Baltic Sea as well as modelling calculations of long-range transboundary transport of mercury in northern Europe.
Field studies were performed in Canada (at Eagle Lake in north-western Ontario) during July 1986 and subsequently at four oligotrophic forest lakes in south-western Sweden during 1988 and 1989 to determine the extent of mercury volatilization. The Canadian investigations involved simultaneous measurements of total vapour-phase mercury concentrations in air sampled immediately above the water surface and over land nearby. A diurnal cycle was observed for mercury emissions from Eagle Lake, with day-time volatilization rates significantly larger than night-time rates. The Swedish field measurements employed a flux chamber. This device was used to determine the rates at which volatile mercury species were emitted from the lakes. Volatilization occurred from each of the Swedish forest lakes during the warmer seasons of the year (with near-surface water temperatures in the 13–23°C range). For day-time measurements, volatilization rates were generally 3–10 ng Hg m−2 h−1. Daytime fluxes were, on average, about 2.5-times larger than night-time fluxes. Experiments conducted during the winter season (with water temperatures just above the freezing point) indicated very little, if any, emission of volatile mercury species from the lake surface.
Mercury concentrations in marine sediment over a large coastal area located opposite a chlor‐alkali complex were measured.The values range from 0.12 μg/g to 6.48 μg/g, d.w. In the same area mercury levels in some organs of the marine phanerogam Posidonia oceanica were measured (leaves 0.022–0.075 μg/g, f.w.; rhizomes 0.033–0.235 μg/g, f.w.; roots 0.080–0.249 μg/g, f.w.).A distinct correlation between the mercury content of the sediment and that present in the different parts of the plant was observed, suggesting a possible use of Posidonia oceanica as a biological indicator.
A review of the available information on the sources and sinks for oceanic mercury (Hg) illustrates the importance of the ocean in the global Hg cycle. The principal source of oceanic Hg is atmospheric deposition with riverine sources contributing about 10% of the total inputs. The primary loss term is gas evasion at the sea surface. Burial of Hg in ocean sediments is a minor sink (10% or less of the total flux). Mass balance estimates suggest that hydrothermal sources do not contribute significantly to the oceanic Hg pool. Overall, about 11 Mmol/yr is currently being added to (and lost from) the ocean reservoir. Much of this Hg is of anthropogenic origin. Mercury deposited to the ocean is effectively reduced, principally by biologically-mediated processes, to elemental Hg and this leads to a rapid recycling to the atmosphere of much of the deposited Hg. Reactive Hg is converted in deeper ocean waters to methylated Hg species. Methylated Hg species and elemental Hg are important components of the Hg pool and the interconversion between the different Hg forms determines, to a large extent, the fate and transport of Hg in deep ocean waters, and the extent of Hg accumulation in marine food chains.
ABSTRACTA flux chamber technique applied to volatile mercury species has been developed and evaluated. This technique can be used to measure the direction and magnitude of mercury transfer between the atmosphere and lake or soil surfaces. Measurements have been performed over four oligotrophic forest lakes in southwestern Sweden during 1988 and 1989. Net emission fluxes of mercury were measured from the lakes. The measured daytime fluxes during the warmer season (water temperatures 13–23 °C) were within the range 3–20 ng h−1 m−2 (average 7.9 ng h−1 m−2). The average night-time fluxes measured during the same season were 2 to 3 times smaller. Two sets of measurements, performed during the winter when water temperatures were ≤ 2 °C, gave flux values close to zero. Flux measurements were also performed over soil in a coniferous forest. Compared to the situation for the forest lakes, the fluxes of mercury over forest soil are much lower in magnitude, with values ranging from approximately − 2 to + 2 ng h−1 m−2 during different seasons. Emission was observed with an average of 0.3 ng h−1 m−2 when soil temperature was about 10 °C, while dry deposition was measured with an average of 0.9 ng h−1 m−2, when soil temperature was < 3 °C.
By using two different radioactive mercury isotopes, detailed information was obtained on the uptake and simultaneous release of mercury by Dunaliella tertiolecta. Hg-203 was added to a well-aged culture, which 2 days later was separated from the medium, washed and cultivated again in a fresh medium containing Hg-197. It was found that an exchange of mercury takes place between the cells and the medium. An increase in the concentration of volatile mercury occurs simultaneously with the maximum concentration of chlorophyll a. Comparing the culture solutions with the blanks, the dissolved mercury shows similar volatility. This leads to the assumption that the main part of the dissolved mercury in the culture solutions is in the inorganic state.
Gas evasion of elemental Hg (Hg) from the open ocean plays a prominent role in the global mercury cycle. Elemental Hg is formed primarily by reduction of ionic Hg in the mixed layer of aquatic systems. By culturing phytoplankton in defined media, and by incubating natural seawater and freshwater samples, we have demonstrated that Hg is produced by microorganisms, with formation rates (0.5 to 10% d–1) similar to those estimated from mass balance studies. Our results also suggest that m microorganisms are the primary Hg reducers in natural waters. Eucaryotic phytoplankton are capable of reducing ionic Hg to Hg but the rate of reduction is insufficient to account for the observed reduction rates found in incubated field samples. Bacteria are thus the more likely Hg reducers. In seawater, cyanobacteria such asSynecococcus may account for much of the mercury reduction, while in the eutrophic, polluted Upper Mystic Lake north of Boston other procaryotic microorganisms are contributing to the overall Hg reductive capacity of the medium. By reducing ionic Hg, microorganisms play a pivotal role in the aquatic biogeochemistry of Hg, not only by enabling evasion to the atmosphere, but by directly decreasing the amount of ionic Hg available for methylation.
Atmospheric mobilization and exchange at the air-water interface are significant features of biogeochemical cycling of Hg
at the Earth's surface. Our marine studies of Hg have been extended to terrestrial aquatic systems, where we are investigating
the tropospheric cycling, deposition and air-water exchange of Hg in the mid-continental lacustrine environs of northcentral
Wisconsin. This program is part of a multidisciplinary examination into the processes regulating the aquatic biogeochemistry
of Hg in temperate regions. Trace-metal-free methodologies are employed to determine Hg and alkylated Hg species at the picomolar
level in air, water and precipitation. We have found Hg concentrations and atmospheric fluxes in these fresh water systems
to be similar to open ocean regions of the Northern Hemisphere. A well constrained mass balance for Hg has been developed
for one of the lakes, Little Rock Lake, which is an extensively studied clear water seepage lake that has been divided with
a sea curtain into two basins, one of which is untreated (reference pH: 6.1) while the other is being experimentally acidified
(current pH: 4.7). This budget shows that the measured total atmospheric Hg deposition (ca. 10 µg m−2 yr−1) readily accounts for the total mass of Hg in fish, water and accumulating in the sediments of Little Rock Lake. This analysis
demonstrates the importance of atmospheric Hg depositional fluxes to the geochemical cycling and bioaccumulation of Hg in
temperate lakes. It further suggests that modest increases in atmospheric Hg loading could lead directly to enhanced levels
of Hg in biota. Analogous modeling for monomethylmercury (MMHg) is as yet limited. Nevertheless, preliminary data for the
atmospheric deposition of MMHg indicate that this flux is insufficient. to account for the amounts of MMHg observed in biota.
An in-lake synthesis of MMHg is implicated. The importance of volatile Hg which is principally in the elemental form, and
its evasion to the atmosphere is also illustrated. We suggest that the in-lake production of Hg° can reduce the Hg (II) substrate
used in the in-lake microbiological synthesis of MMHg.
Mercury is emitted from soil and water surfaces, but few actual direct flux measurements have been reported. During June, 1994 we performed the first micrometeorological measurements of Hg vapor fluxes over a boreal forest lake. Using highly precise methods with multiple replicate samplers, we measured concentration gradients of Hg vapor, CO2 and H2O over the lake surface. Mercury was readily emitted from the lake surface, and we found no evidence of Hg dry deposition to the lake. Emission rates over the lake averaged 8.5 ng m2 h–1, and appeared to be weakly influenced by water temperature and solar radiation. These fluxes were somewhat higher than those previously measured using surface chambers at this site.
The potential ability of humic substances to reduce Hg(II) to Hg(0) in aqueous systems and, consequently, strongly influence
Hg speciation and mobility in the environment is known but has not been studied in detail. A demonstration of the redox behavior
of Hg in the presence of humic substances is made in the present work. Calculations show that the reduction is thermodynamically
possible. The effects of some chemical parameters (pH, aerobic/anaerobic conditions, presence of chloride) on the process
were studied experimentally. Hg(0) production was highest in O2-free systems in the absence of chloride at pH ca 4.5, when ca 25% of initially 2x10−6 M Hg(II) was reduced to Hg(0) in 50 hr. The presence of a competing ion (10−4 M Eu) in the system as well as methylation of the carboxyl groups in the humic substance considerably reduced the Hg(0) production.
The practical importance of the abiotic reduction of Hg in the environment is pointed out.
The cycling of dissolved gaseous Hg (DGM) has been examined in our studies of the troposphericHg cycle, air-water exchange
and their importance to the biogeochemical behavior and fate of Hg in temperate lakes. Five seepage lakes in northcentral
Wisconsin, ranging in pH from 4.7 to 7.2, have been studied under a variety of limnological conditions which included the
following seasonal periods: summer (peak stratification), fall (following turnover) and late winter (under ice). Analytically,
DGM was determined after purging lake water with argon and collecting the volatile Hg fraction on gold coated sand. The Hg
collections were analysed by pyrolysis in a two-stage Au amalgamation gas train with detection by atomic fluorescence spectroscopy
(AFS). In addition, chemical speciation of the volatile fraction has been achieved by trapping on a nondestructive substrate
followed by gas chromatographic separation and AFS detection. The DGM consists principally of elemental Hg (Hgo) under all sampling conditions, with no significant contribution from volatile organic Hg species (detection limit of 3 femtomolar).
Atmospheric gaseous Hg, which also consists principally of Hgo, was measured and the air-water partitioning determined. In general, the lake waters have been supersaturated with Hgo relative to the atmosphere. Supersaturation was greater in the summer, ranging from ca. 1.4 to 12 times (x) the saturation
concentration. During the other sampling periods, Hgo ranged from saturation to ca. 7x the equilibrium concentration. The flux of Hg from the lakes due to gas evasion is significant
and is estimated at approximately 10% of the annual atmospheric input of Hg to the lakes. An apparent relationship between
Hgo and pH has been observed with lakes of lower pH having smaller Hgo concentrations.
Mercury (II) solutions were irradiated by a simulated sunlight in the presence of humic acid (HA) or fulvic acid (FA). Results show that, under the experimental conditions and the FA and HA chosen, less than 20% of the Hg in solution was photolysed with a rate of (1.630.29)10–2 s–1 (n=23) and the rest of (2.380.40)10–4 s–1 (n=23) depending on the substitutes of humic substances to which Hg were bond. The sunlight photolysis lifetimes were estimated to be 4 and 250 sunlight hours respectively under summer conditions at Stockholm latitude.
In order to evaluate and understand the processes of water-air and soil-air exchanges involved at background sites, an intensive field measurement campaign has been achieved during the summer of 1995 using high-time resolution techniques (10 min) at two sites (land and water) in southern Québec (Canada). Mercury flux was measured using a dynamic flux chamber technique coupled with an automatic mercury vapour-phase analyser (namely, Tekran®). The flux chamber shows that the rural grassy site acted primarily as a source of atmospheric mercury, its flux mimicked the solar radiation, with a maximum daytime value of ∼ 8.3 ng m−2 h−1 of TGM. The water surface location (St. Lawrence River site located about 3 km from the land site) shows deposition and evasion fluxes almost in the same order of magnitude (−0.5 vs 1.0 ng m−2 h−1).The latter is influenced to some extent by solar radiation but primarily by the formation of a layer of stable air over the water surface in which some redox reactions might promote evasion processes over the water surface. This process does not appear over the soil surface. As a whole, soil-air exchange rate is about 6–8 fold greater than the water-air exchange.
Total mercury concentrations were determined in water samples from ten vertical profiles in the western Mediterranean. Most Hg concentrations ranged from 0.5 to 4 pM, with a geometric mean of 2.26 pM. Such concentrations are in the same range as those measured in the North Atlantic and equatorial Pacific waters. There is no indication that the presence of geothermal activity or cinnabar deposits around the Mediterranean basin induces higher mercury concentrations in waters. Vertical concentration profiles were characterized by a maximum just below the thermocline, which is mainly developed in regions with relatively high primary production in the overlying waters. These observations support the remobilization model according to which, the mercury, associated with degradable organic matter, is solubilized from the particles accumulated in the thermocline layer. Additional measurements of certain mercury species, including reactive mercury (HgR) and gaseous species [elemental mercury (Hg°) and dimethylmercury (DMHg)], were performed on three profiles in the Alboran Sea and the Strait of Gibraltar. While 50% of the total mercury consisted of unidentified organic association, a maximum of the three determined species were observed below the thermocline: up to 0.71 pM, 0.43 pM and 0.30 pM for HgR, Hg° and DMHg, respectively. DMHg and Hg° appear to be formed in the low oxygen zone. A specific methylation rate of 3 × 10−9 s−1 can be estimated, which is six times higher than the values proposed for the North Atlantic waters (Mason et al., 1995a, Water, Air and Soil Pollution, 80, 665-677).
A review of the available information on global Hg cycling shows that the atmosphere and surface ocean are in rapid equilibrium; the evasion of Hg0 from the oceans is balanced by the total oceanic deposition of Hg(II) from the atmosphere. The mechanisms whereby reactive Hg species are reduced to volatile Hg0 in the oceans are poorly known, but reduction appears to be chiefly biological. The rapid equilibrium of the surface oceans and the atmosphere, coupled with the small Hg sedimentation in the oceans makes deposition on land the dominant sink for atmospheric Hg. About half of the anthropogenic emissions appear to enter the global atmospheric cycle while the other half is deposited locally, presumably due to the presence of reactive Hg in flue gases. We estimate that over the last century anthropogenic emissions have tripled the concentrations of Hg in the atmosphere and in the surface ocean. Thus, two-thirds of the present Hg fluxes (such are deposition on land and on the ocean) are directly or indirectly of anthropogenic origin. Elimination of the anthropogenic load in the ocean and atmosphere would take fifteen to twenty years after termination of all anthropogenic emissions.
Mercury speciation was determined in samples of surface waters of the North Sea. Seventeen stations were visited including coastal waters off the Thames, Humber, Scheldt, Rhine, Ems, Weser and Elbe estuaries. Mercury concentrations measured in the present study are significantly lower than previous estimates for the North Sea, but they are similar to concentrations recently determined in other coastal environments. Concentrations of total dissolved mercury ranged from 0.9 to 4.8 pM with 0.4 to 1.8 pM as dissolved reactive mercury, representing on average about 30% of the total dissolved mercury. Particulate mercury constituted between 13 and 82% of the total mercury (dissolved and particulate) depending on the distribution of suspended particulate matter, with the highest proportions found near the coasts in the southern North Sea. The mercury content of the seawater particles varied between 116 and 484 ng·g−1 with 6% on average as particulate monomethylmercury. A longitudinal profile was completed in the outer estuary of the Elbe river; mercury concentrations reached 16.4 pM for dissolved mercury and 595 pM for particulate mercury in the low salinity region, indicating that the Elbe estuary is contaminated with mercury. This is similar to the contamination measured recently in the Scheldt estuary. The net input of mercury from the Elbe river to the North Sea was estimated at 0.43 kmol·a−1 for dissolved mercury and 4.24 kmol·a−1 for particulate mercury. The mercury concentrations measured in the Elbe estuary are used to estimate the total mercury input from freshwaters to the North Sea. It is comparable to direct atmospheric inputs to the North Sea.
Elemental mercury accounts for 10–50% of the dissolved mercury in lakes but plays a vital role in the cycling of this element in lacustrine environments. The view is advanced that a large fraction of the Hg(0) is generated by photochemical reactions in the surface waters. Possible mechanisms for the Hg(0) production are discussed including homogeneous photolysis of dissolved Hg species and photoreduction processes involving organic molecules and inorganic particulates in water.
We have assessed the effect of solar radiation on the formation of dissolved gaseous mercury (DGM) in lake water samples incubated in situ. In temperate forested lakes, solar radiation induced the formation of DGM, whereas in Lake Erie, light had no effect. In lakes where photo-induced DGM production was found, DGM concentrations were higher near the surface, whereas in Lake Erie, DGM levels peaked in the metalimnion. In high DOC lakes, removal of UVB radiation did not affect DGM production, whereas in a low DOC lake, DGM production rates were significantly lower in the absence of UVB radiation, suggesting that DOC compounds are reducing the availability of UVB radiation for photoreduction of Hg. The relationship between light intensity and DGM production was nonlinear in Ranger Lake. Above ∼-3 MJ m−2 total incident radiation, a plateau was reached at about 400 fM during the summer and about 150 fM during the fall. In this lake, a clear diel pattern of DGM levels was found which paralleled that for total solar radiation. Spiking of samples with Hg(II) prior to incubation in Ranger Lake greatly increased the DGM production rate, suggesting that photoreducible Hg(II) complexes were limiting DGM production. Filtration through GF/F filters or sterilization by heating prior to incubation did not decrease DGM production rates, suggesting that agents promoting DGM formation in Ranger Lake were either dissolved or colloidal. DGM levels in outflows of two high DOC drainage lakes were higher than in inflows, confirming that the lakes were sites of DGM production.
Formation of dissolved gaseous mercury (DGM) was measured in lake water incubated at midday in Teflon bottles. DGM production was photoinduced as transparent bottles yielded DGM concentrations that were 2.4-9 times higher than dark controls. These results provide the first experimental evidence obtained in the field of a direct link between solar radiation and DGM production. A positive relationship was found between photoinduced DGM production at different times of the year and incident radiation. Removal of UV(B) light or addition of hydrogen peroxide during incubation did not result in significant changes in DGM levels. A diel pattern in DGM production was observed, and a depth profile of DGM revealed that most of the production was occuring in the epilimnion. It is concluded that sunlight plays a key role in DGM production in the epilimnion and may alter the fluxes of Hg in aquatic ecosystems.
A floating flux chamber, built of Plexiglas, has been developed to measure vapour-phase mercury fluxes over aquatic systems. The chamber is connected via Teflon tubes to a semi-automatic sampling device and to a mercury analyzer (battery-powered) to perform the determination of mercury emission in situ. Relatively low chamber blanks have been observed both in laboratory and in field conditions. The low detection limit of the analyzer (0.5 pg of mercury) allows measurements of mercury concentration in a short period of time (10 min). In this way it is possible to follow the real-time temporal trend of mercury emission. Some data obtained with this flux chamber in selected areas of the Mediterranean basin are reported.
Elemental mercury is formed in aqueous solution by the chemical reduction of mercuric ion in the presence of humic acid. The reduction proceeds via first order kinetics (rate constant, 0.009 hour-(1)) and is depndent on pH. The reaction mechanism involves interaction of the ionic metal species with the free radical electrons of the humic acid.
The partitioning of gaseous mercury between the atmosphere and surface waters was determined in the equatorial Pacific Ocean.
The highest concentrations of dissolved gaseous mercury occurred in cooler, nutrient-rich waters that characterize equatorial
upwelling and increased biological productivity at the sea surface. The surface waters were supersaturated with respect to
elemental mercury; a significant flux of elemental mercury to the atmosphere is predicted for the equatorial Pacific. When
normalized to primary production on a global basis, the ocean effluxes of mercury may rival anthropogenic emissions of mercury
to the atmosphere.
Exchange mercury between atmosphere and vegetation. In: Fifth In-ternational Conference on 'Mercury as a Global Pollutant
- Lodenius M E Tulisalo
- Soltanpour
Lodenius M, Tulisalo E, Soltanpour-Gargari A. Exchange mercury between atmosphere and vegetation. In: Fifth In-ternational Conference on 'Mercury as a Global Pollutant'. Ž. Rio de Janeiro Brazil, May 23᎐28, 1999.
Air᎐water cycling of mercury in lakes Mercury pollution. Integration and synthesis Sea᎐air partitioning of mercury in the equatorial Pacific Ocean
- Fitzgerald Wf
- Rp Mason
- Gm
- F203᎐220 Dulac
- Kim
- Jp
- Fitzgerald
- Lindberg
- Meyers Tp Se
- Munthe
Fitzgerald WF, Mason RP, Vandal GM, Dulac F. Air᎐water cycling of mercury in lakes. In: Watras CJ, Huckabee JW, editors. Mercury pollution. Integration and synthesis. Lewis Publishers, 1994:203᎐220. Kim JP, Fitzgerald WF. Sea᎐air partitioning of mercury in the equatorial Pacific Ocean. Science 1986;23:1131᎐1133. Lindberg SE, Meyers TP, Munthe J. Evasion of mercury vapor from the surface of a recently limed acid forest in Sweden.
Global and regional mercury cycle: sources, fluxes, and mass balance Mechanistic steps in the photoreduction of mer-cury in natural waters Water᎐air and soil᎐air exchange rate of total gaseous mercury measured at background sites
- Ebinghaus R Vasiliev
In: Baeyens W, Ebinghaus R, Vasiliev O, editors. Global and regional mercury cycle: sources, fluxes, and mass balance. Kluwer Academic Publishers, 1996:249᎐272. Nriagu JO. Mechanistic steps in the photoreduction of mer-cury in natural waters. Sci Total Eviron 1994;154:1᎐8. Poissant L, Casimir A. Water᎐air and soil᎐air exchange rate of total gaseous mercury measured at background sites. Atmos Environ 1998;32:883᎐893.
Photochemical behavior of inorganic mercury compounds in aqueous solution
- Xiao
Air–water cycling of mercury in lakes
- Fitzgerald
Mercury in the Lena Delta and Laptev Sea
- D Cossa
- M Coquery
- J-M Martin