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Recharge and sustainability of a coastal aquifer in northern Albania
Abstract
The River Mati in Albania has formed a coastal plain with Holocene and Pleistocene sediments. The outer portion of the plain is clay, with three underlying aquifers that are connected to an alluvial fan at the entry of the river into the plain. The aquifers supply water for 240,000 people. Close to the sea the aquifers are brackish. The brackish water is often artesian and found to be thousands of years old. Furthermore, the salinity, supported by δ18O results, does not seem to be due to mixing with old seawater but due to diffusion from intercalated clay layers. Heavy metals from mines in the upstream section of River Mati are not an immediate threat, as the pH buffering of the river water is good. Moreover, the heavy metals are predominantly found in suspended and colloidal phases. Two sulphur isotope signatures, one mirroring seawater sulphate in the brackish groundwater (δ34S >21 ‰) and one showing the influence of sulphide in the river and the fresh groundwater (δ34S <10 ‰), indicate that the groundwater in the largest well field is recharged from the river. The most serious threat is gravel extraction in the alluvial fan, decreasing the hydraulic head necessary for recharge and causing clogging of sediments.
... Further, rapid and uncontrolled urbanization has a marked impact on groundwater quality too [17][18][19]. The hydrogeological investigations performed in Albania have already documented several examples of groundwater quality deterioration by pumping near the recharge areas of intergranular aquifers [20][21][22][23][24]. ...
... As shown by environmental hydrochemical and isotope investigations, the occurrence of brackish water in the periphery areas is related to the exchange processes between the Ca 2+ ions of the groundwater and the Na + ions of clay intercalating layers, remnants of the Holocene Sea transgression [20,23,47]. ...
... It has been calculated that the total influence of the pumping in the new wellfield of Fushe Milot should be less than 1 m in the center of the existing wellfield of Fushe Kuqe, and no intensification of the sea water intrusion will happen. This is supported by observation of the groundwater level and chemical analyses [20,23]. ...
The municipal water supply, related mainly to the cities of Albania, began to develop in the second half of the 19th century and very intensively after 1945. Today, the reported mean water production for the cities, on average, is about 300 l/capita/d, including drinking and industrial water supplies. The territory of Albania has an uneven distribution of very heterogeneous aquifers conditioning often the difficulty of municipal water supply solutions. In this article, are analyzed and classified the hydrogeological aspects of the water supply sources of the settlements, which are summarized in five groups: (a) wells in alluvial intergranular aquifers; (b) karst springs; (c) wells in karst aquifers; (d) springs in fissured rocks; and (e) mixed water sources. For each group of the water supply sources, the main concerns regarding the quantity and quality problems are analyzed, facilitated by the description of a variety of representative examples of different situations. Based on the gained experience, important recommendations are given for the better understanding of hydrogeological aspects of water supply systems, related to the river water recharge areas, the seawater intrusion in coastal aquifers, and the high vulnerability of karst aquifers, as well as trans-boundary aquifers. However, the main problem of public water supply of Albania remains the poor management of water supply systems, which is reflected in the significant water losses, as well as the low public awareness of requests for sustainable use.
... Further, rapid and uncontrolled urbanization has a marked impact on groundwater quality too [17][18][19]. The hydrogeological investigations performed in Albania have already documented several examples of groundwater quality deterioration by pumping near the recharge areas of intergranular aquifers [20][21][22][23][24]. ...
... As shown by environmental hydrochemical and isotope investigations, the occurrence of brackish water in the periphery areas is related to the exchange processes between the Ca 2+ ions of the groundwater and the Na + ions of clay intercalating layers, remnants of the Holocene Sea transgression [20,23,47]. ...
... It has been calculated that the total influence of the pumping in the new wellfield of Fushe Milot should be less than 1 m in the center of the existing wellfield of Fushe Kuqe, and no intensification of the sea water intrusion will happen. This is supported by observation of the groundwater level and chemical analyses [20,23]. ...
The municipal water supply, related mainly to the cities of Albania, began to develop in the second half of the 19th century and very intensively after 1945. Today, the reported mean water production for the cities, on average, is about 300 l/capita/d, including drinking and industrial water supplies. The territory of Albania has an uneven distribution of very heterogeneous aquifers conditioning often the difficulty of municipal water supply solutions. In this article, are analyzed and classified the hydrogeological aspects of the water supply sources of the settlements, which are summarized in five groups: (a) wells in alluvial intergranular aquifers; (b) karst springs; (c) wells in karst aquifers; (d) springs in fissured rocks; and (e) mixed water sources. For each group of the water supply sources, the main concerns regarding the quantity and quality problems are analyzed, facilitated by the description of a variety of representative examples of different situations. Based on the gained experience, important recommendations are given for the better understanding of hydrogeological aspects of water supply systems, related to the river water recharge areas, the seawater intrusion in coastal aquifers, and the high vulnerability of karst aquifers, as well as transboundary aquifers. However, the main problem of public water supply of Albania remains the poor management of water supply systems, which is reflected in the significant water losses, as well as the low public awareness of requests for sustainable use.
... The depression was successively filled up mainly with alluvial sediments the thickness of which ranges from about 20-30 m in the South (Tirana) through 60-80 m in the Center (Fushe Kruja) up to about 200 m in the North (Fushe Kuqe) [Tartari and Dakoli, 2001]. Quaternary sediments, gravel and sand sandwiched between clay layers, are of Pleistocene age, formed after the last glacial maximum when the sea level rose from 120 below the present level and the seashore retreated from a position about 50 km offshore outside the present coastline [Kumanova et al., 2014]. The clay cover is likely to have been formed during the rapid seawater regression later in the Holocene [Kumanova, et al., 2014]. ...
... Quaternary sediments, gravel and sand sandwiched between clay layers, are of Pleistocene age, formed after the last glacial maximum when the sea level rose from 120 below the present level and the seashore retreated from a position about 50 km offshore outside the present coastline [Kumanova et al., 2014]. The clay cover is likely to have been formed during the rapid seawater regression later in the Holocene [Kumanova, et al., 2014]. ...
... A few wells (P22, P14, A25), located about 10 km to the east of coast line, south of River Droja, also fall within the zone III. This brackish groundwater should rather be relict sea water [Kumanova et al., 2014], trapped C3 in the east. The groundwater in this cluster is characterized by moderate values of Cland TDS (87.72 ± 31.60 mg/l and 445.69 ± 103.56 mg/l, respectively), but is typically soft (average TH = 7.17 ± 2.97 ⁰dH) water. ...
During the research, 71 groundwater samples were collected over a 300 km2 area of Tirana-Fushe Kuqe alluvial aquifer extension (central-western Albania) and subsequently analyzed for 11 parameters (pH, K+, Na+, Ca2+, Mg2+,HCO3-, Cl-, SO42-, NO3-, TH and TDS). Both geochemical conventional (Piper and Chadha diagrams) methods of groundwater classification and multivariate statistical (principal components analysis – PCA and hierarchical cluster analysis – HCA) methods were applied to the dataset to evidence the geochemical processes controlling groundwater geochemistry evaluation through the aquifer. The conventional geochemical methods revealed four (G1–G4) hydrochemical groups where the dominant group is G2 the samples of which are from unconfined to semiconfined recharge zone and the majority of them have Ca-Mg-HCO3
groundwater. Group G3 includes the samples from the confined coastal aquifer having Na-Cl groundwater. Group G1 includes three groundwater samples of Ca-Mg-SO4
from the central part of the aquifer, while group G4, the samples of which are spatially
located between G3 and G2 zones, has Na-HCO3 groundwater. The first four components of the PCA account for 85.35% of the total variance. Component PC1 is characterized by very high positive loadings of TH, Ca2+, and Mg2+,suggesting the importance of dissolution processes in the aquifer recharge zone. Component PC2 is characterized by very high positive loadings in Na+, K+, and Cl- and moderate to high loadings of TDS, revealing the involvement of seawater intrusion and diffusion from clay layers. On the basis of their variable loadings, the first two components are defined as the “hardness” and “salinity”, respectively. The HCA produced four geochemically distinct clusters, C1–C4. The samples of cluster C1 are from the coastal confined aquifer and their groundwater belongs to the Na-Cl type. The samples from cluster C2 are located in the south and east recharge areas and most of them have Ca–Mg–HCO3 groundwater, while the samples from cluster C3, which are located in the northeastern recharge zone, have Mg-Ca–HCO3 groundwater. Finally, cluster C4 includes two groundwater subgroups having Na-Cl-HCO3 and Na-Mg-Cl-HCO3 groundwater in the vicinity of cluster C1 as well as Na-HCO3 -Cl and Na-MgHCO3 -Cl groundwater next to cluster C2 and C3.
... The groundwater in Mati coastal plain in the northern Albania serves as water source for about 400,000 people, and there was a concern that this pumping rate may cause salt water intrusion [12]. In the catchment, there are several abandoned and active copper mines and the sulfate in river has an isotopic ratio typical of sulides. ...
... Thus, sea water intrusion is not a current threat. [12]. In the plain, the δ 34 S ratios are mirroring recharge from river Mati, which has a δ 34 S ratio mirroring sulide oxidation in mining areas in the catchment. ...
... Staple diagram with δ 34 S ratios in groundwater indicating recharge from the river Mati with sulfate having sulide origin from oxidation of waste rock from copper mines [12]. The high δ 34 S ratios in sea near wells are above the sea water ratio (21‰), which indicates sulfate reduction in intercalated clay layers. ...
... The heavier saltwater flows in from the sea and a wedge-shaped body of saltwater develops beneath the lighter freshwater, with the freshwater thickness decreasing from the wedge towards the sea. The presence of sea water intrusion in Fushë Kuqe aquifer is reported by different authors [5][6][7][8][9][10][11][12], whose opinions have some differences regarding salt water origin along the western coastal area of the aquifer. ...
... In contrast with Ref. [12], who reported that there is no any relation between δ 18 O and chloride concentrations, in Fig. 3, it might be seen that the points of sample No. 6, 8, 9, 10 fall on the fresh water-seawater mixing line, indicating that the groundwater of these coastal wells is under the influence of the seawater intrusion. ...
The Fushë Kuqe costal aquifer is a typical confined alluvial aquifer, located in northwestern Albania. The aquifer medium consists of alternating and discontinuous layers of water-bearing gravel and sand with silt-clay impermeable layers giving to aquifer a multilayer character. Along the Mat River the aquifer seems to be continuous, whereas at distances 1.5 -2 km from the river two to four or more aquifer layers appear separated by clayey layers. The transmissibility of the aquifer is generally high in the central part of the plain, on both sides of Mat River, where it is about 4000 to 8000 m²/d, and gradually decreases to about 500-1000 m²/d at the northern and southern periphery of the aquifer (Eftimi, 2003). The aquifer recharge occurs mainly through water infiltration from the River Mat gravelly bed in the North, and from Droja river in the South, while its natural discharge proceeds to the Adriatic sea.
Based on chloride and TDS content in groundwater, an advancement of sea water intrusion into aquifer fresh water was revealed. The direction of sea water wedge from coastal southwestern sectors towards Gorre and Fushe Kuqe, where pumping station are located (Cenameri and Beqiraj, 2016), favors the opinion that it was caused by a decrease of groundwater pressure due to the high groundwater pumping. An increase of chloride content in groundwater through time was found, which means that sea water intrusion towards the fresh aquifer water is still advancing and is caused by both intensification of groundwater pumping for public water supply and by the private drilling of artesian private wells (Cenameri and Beqiraj, 2016).
By using Simpson ratio (SR) (Todd, 1959) and Jones ratio (JR) (Jones et al., 1999) for investigating seawater intrusion in Fushe Kuqe aquifer, it was recently found that most of groundwater sample fall in the fresh water (SR<0.5; JR>0.86) category as it could be expected for shallow wells (<50m deep) which tap the first aquifer (Eftimi, 2003). Only two wells that tap the second (90m deep) and third aquifer (>150m deep) in the near shore line, show high (3.8 and 7.55) SR values and low (1.0 and 0.8) JR values, respectively.
The δ18O and δ2H values vary within a narrow (-6.78 to -7.96 and -41.86 to -50.53, for 18O and 2H, respectively) range and do not correlate with salinity as it could be expected when a single source of TDS and Cl exists. The lack of correlation between chloride and δ18O indicates that the brackish groundwater is not formed by the mixing in of sea water (Kumanova et al, 2014). In fact, the δ18O and δ2H values do not indicate any enrichment toward sea water isotopic composition.
REFERENCES
Cenameri S., Beqiraj A., 2016. Assessment of seawater intrusion in Fushe Kuqe aquifer, Albania. Bulletin of the Geological Society of Greece. L/2. Proceedings of EGE 2016, Thessaloniki, Greece. 665-661.
Eftimi R. 2003. Some consideration on seawater-freshwater relationship in Albania coastal area. In: Coastal Aquifers Intrusion Technology: Mediterranean countries, J.A.Lopez-Gaeta, J.De Dios Gomez, J.A. dela Orden & G. Ramos, L. Rodrigues editors. IGME Proceedings, 239-250.
Jones, B.F., A. Vengosh, E. Rosenthal, and Y. Yechieli, 1999. Geochemical investigations, in Bear, Jacob, and others, eds., Seawater intrusion in coastal aquifers—Concepts, methods and practices, Dordrecht, The Netherlands, Kluwer Academic Publishers, p. 51–71.
Kumanova, Xh, Marku, S, Fröjdö, S, Jacks, G. 2014. Recharge and sustainability of a coastal aquifer in Northern Albania. Hydrogeology Journal. 22, (4), 883–892.
Todd, D. K. 1959. Ground Water Hydrology, John Wiley and Sons. Inc, New York, 277–294.
... This investigation was initiated after a study of the Mati Plain aquifers which were found to be almost entirely fed by the River Mati via an alluvial fan (Kumanova et al. 2014). Metals are found in offshore areas (Rivaro et al. 2004(Rivaro et al. , 2005 indicating a sizable transport via the river from upstream sites. ...
... This would give an indication of the ecotoxicity of the metals and also provide hints on how to decrease the transport. One of the aims is to assess the risk of migration of metals into the groundwater in the alluvial fan of the River Mati (Kumanova et al. 2014). ...
The transport of metals was investigated at 15 sites in the River Fani and the River Mati in N. Albania. There are numerous abandoned copper mine sites and one active mine upstream in the River Fani catchment. Upstream in the Mati catchment, there is a large chromium smelter and several chromium mines. Water samples and sediment samples were collected at all the sites. Moreover, the water samples at a number of the sites were fractionated by filtering and by dialysis to assess in which form the metals were transported. There was a relatively larger abundance of metals in the suspended (unfiltered water) and colloidal phases (filtered by 0.2-μm filters). Metal concentrations in water and in sediments decreased rapidly downstream away from point sources, approaching background levels within 10 km, indicating that the larger fractions could settle in the sediments. The River Mati recharges a large coastal aquifer via an alluvial fan at the entrance into the coastal plain. There does not seem to be any risk of metals appearing in the groundwater, as the transport mode is that of largely suspended and colloidal matter. The offshore metals in the Adriatic Sea are likely to be flushed out during rainy seasons with high discharge. The bioavailability of the metals is likely to be low except for just downstream of point sources. In view of the relatively large fractions of metals found in the suspended and colloidal phases, the establishment of sedimentation basins downstream point sources would decrease the export to the rivers.
... This increasing groundwater salinity has been attributed to several factors such as upward movement of deep saline paleowater (Santucci et al., 2016;Larsen et al., 2017), manufacturing and oceanic pollution or wastewater release (Horst et al., 2011;Mongelli et al., 2013), agricultural activities (irrigation water return flow) (Cruz-Fuentes et al., 2014) and leaching of lithology constituents (evaporate, gypsum, halites) (Cendon et al., 2008;Ouhamdouch et al., 2017). Other drivers include influence of oceanic sprays (Koehler and Wassenaar, 2010); hydrodynamic diffusion and density dynamics, tidal influences, aquifer features, recharge and discharge situations in coastal environments (Bear et al., 1999;Mao et al., 2006;Narayan et al., 2007;Rahmawati et al., 2013;Werner et al., 2013;Kumanova et al., 2014). ...
Coastal areas are usually characterized by a high human population with attendant groundwater pollution through increased salinization from varied sources. This study was done to assess the pollution status, suitability of groundwater and associated hydrogeochemical processes of the shallow sandy aquifer near the coastal section of Lagos State, Southwestern Nigeria. A total of fifty-nine hand-dug wells were randomly selected, from which water samples were collected and subjected to physicochemical and statistical analyses. Water quality indices (Pollution Index of Groundwater (PIG) and Irrigation quality indices) and Chloro-Alkaline Indices (CAI 1&2) were calculated while plots of Gibbs and Piper diagrams as well as factor analysis were also carried out. The order of abundance of dissolved ions were Na>Ca>Mg>K for cations and HCO3>Cl>SO4>NO3 for anions. Presently, there appears to be no pollution threat to the groundwater, and the bulk of the samples are found fit for agricultural use. Rock weathering, ion exchange, occasional sea surge and municipal contamination activities constitute the geochemical processes affecting the groundwater quality in the study area. It could be postulated that consistent activities of sea water surge and municipal contamination might impair the groundwater quality of the sandy aquifers in the nearest future.
... Early studies in the Mediterranean area were developed in Israel [92,93], while since the year 2005, there has been a growing legacy of studies employing these techniques. Most of the studies used stable isotopes to distinguish between different GW origins [94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113], while some of them used radioactive isotopes to determine the residence time of GW [114][115][116], that is, one of the very few pieces of information allowing researchers to distinguish between actual and paleo SWI. These last elements have also been used to study surface water/groundwater interaction; for example, in a recent paper from Mayer et al. [117], short-lived radioactive isotopes, such as radon-222, allowed not only for the determination of the amount of exchange between different water bodies, but also for the ability to precisely derive GW flow velocities and saturated hydraulic conductivities, which are vital parameters to constrain numerical simulations. ...
The Mediterranean area is undergoing intensive demographic, social, cultural, economic, and environmental changes. This generates multiple environmental pressures such as increased demand for water resources, generation of pollution related to wastewater discharge, and land consumption. In the Mediterranean area, recent climate change studies forecast large impacts on the hydrologic cycle. Thus, in the next years, surface and ground-water resources will be gradually more stressed, especially in coastal areas. In this review paper, the historical and geographical distribution of peer-review studies and the main mechanisms that promote aquifer salinization in the Mediterranean area are critically discussed, providing the state of the art on topics such as actual saltwater wedge characterization, paleo-salinities in coastal areas, water-rock interactions, geophysical techniques aimed at delineating the areal and vertical extent of saltwater intrusion, management of groundwater overexploitation using numerical models and GIS mapping techniques for aquifer vulnerability to salinization. Each of the above-mentioned approaches has potential advantages and drawbacks; thus, the best tactic to tackle coastal aquifer management is to employ a combination of approaches. Finally, the number of studies focusing on predictions of climate change effects on coastal aquifers are growing but are still very limited and surely need further research.
... Coastal aquifers (CAs) can be affected and even threatened by high demand for fresh water. Such conditions are usually caused by a lack of both adequate water management and water problem analysis (Kumanova et al., 2014;Hern andez, 2011). As the main source of fresh water for various coastal regions, it is imperative that CAs be properly developed considering that more than 60% of the global population is concentrated in coastal areas that comprise only 10% of the Earth's surface, and this percentage is expected to rise to 75% (Chatton et al., 2016;Unsal et al., 2014). ...
Inadequate water management stresses water resources, impacting not only economic but also social and environmental sectors. Its consequences negatively impact the gross domestic product of affected countries by limiting economic growth. Arid coastal regions are the most severely affected due to the confluence of periods of greater demand and periods of greater scarcity. In such regions, the most reliable sources of fresh water are coastal aquifers (CAs); however, due to their current overexploitation, CAs are encountering problems such as marine intrusion (MI). In Mexico, the Costa de Hermosillo aquifer (CHA) is one of the most exploited, and at present it is experiencing the negative consequences of MI, which are harming not only quality of life of the inhabitants but also irreparably damaging the regional environment. This article aims to formulate a coastal aquifer management plan through a case study that takes environmental costs into consideration to support decision-making processes and seeks to show how sustainability strategies can be applied to recover, conserve, and sustainably exploit CAs water resources. The originality/value of this paper is the interaction of the sustainability pillars that allowed an environmental accounting evaluation as a step toward the implementation of future holistic strategies to facilitate water resource management in a sustainable development framework.
In order to understand the interaction between groundwater, surface water and sediments, there is a need for speciation analysis of trace elements in the mentioned matrices. This could be done experimentally or by calculation with e.g. thermodynamic codes. This article will give a short overview of methods with some examples and results. Speciation in water could be determined by thermodynamic calculations with e.g. PHREEQC or Visual MINTEQ. Experimental speciation in water could be done by ultrafiltration or dialysis in situ. If applicable, in situ dialysis in the field is simple with little need of equipment. Speciation of trace elements in drinking water is of special interest to assess possible health effects. Speciation of trace elements in sediments and soils can be done by any one of the numerous selective extractions. Which speciation approach depends on which trace elements are of interest. A common need is to get information about plant uptake of specific elements.
Coastal aquifers are subject to considerable stress globally. As coastal regions are densely populated areas, the water requirements are large which includes a demand for water within agriculture. Tertiary sections of the coastal sediments in southern Kerala have been investigated since the 1980s, and results are presented here. Four sections have been identified in the Tertiary sequence in southern Kerala, the Warkali, the Quilon, the Vaikom and the Alleppey beds. The Warkali and Vaikom beds are productive aquifers. The Warkali beds are extensively used for water extraction, and the groundwater level has sunk below sea level while there are boreholes into the Vaikom beds that are still artesian having a pressure head of up to 6 m above the present sea level. This indicates that the offshore cover of fine sediments is tight and little discharge occurs onto the seabed. The investigation has shown that the groundwater was recharged 22–34 Ka BP. when the sea level was 80–90 m below the present sea level. The recharge may have been interrupted by a drier period. Some of the samples show elevated chloride levels, but isotopic investigations (δ¹⁸O) show that this is not due to seawater intrusion but rather due to diffusion from pore water in intercalated clay layers. In spite of considerable pumping from the aquifers, there has been no remarkable change in chloride levels over the past 35 years. This is probably due to the freshwater/saline interface which is offshore, a common phenomenon caused by the low sea level during the last glacial maximum. Some of the samples show a reduced water with elevated iron concentrations. Unlike in the Bengal Delta, there is no connection with elevated arsenic concentration. The arsenic concentration has been found to be below 10 µg/l.
The groundwater circulation of transboundary aquifers of the Mali Gjere massif and of the Prespa-Ohrid Lakes is described. The Blue Eye Spring (or Bistrica Spring) issues from the Mali Gjere karst massif with the mean discharge of 18.4 m³/s. Using environmental tracer methods (isotope and hydrochemical) we have determined that the Blue Eye spring is recharged to the extent of 30 to 35 % by the gravely aquifer of Drinos River valley. The high sulphate content of the Drinos River replenishing the gravely aquifer is responsible also for increased sulphate content of the Blue Eye Spring. A karst massif separates the Prespa and Ohrid Lakes and the Prespa Lake is 155 m higher then the Ohrid Lake. Using environmental isotopes we determined that from 38 to 53% of the water from some big karst springs issuing in Ohrid Lake is recharged by the Prespa Lake through the Mali Thate-Galichica karst massif. Water tracing has established karst water flow velocities up to 3200 m/h.
Hydrogeological investigations along the Chennai (Madras) coast showed that groundwater levels are lower than mean sea level, often as much as -3 to -6m. However, the quality of groundwater in the near-surface unconfined aquifer, tapped by shallow wells, is reasonably fresh, though deeper wells show distinct signs of sea-water intrusion. Presence of fresh water below mean sea level in the absence of positive fresh water head is not possible in a coast line having hydraulic continuity with the marine environment. Detailed studies show that a narrow fresh water ridge, created by the beach dune complex, exists along the coast Along most of the beach ridge groundwater abstraction is relatively less and also there is regular recharge into the aquifers from monsoon rains, and thus the staue water level remains slightly above mean sea level along a narrow zone for most of the coastline. This fresh water ridge prevents contamination of the shallow aquifer to the west of the ridge, even though the water levels fall below mean sea level in the aquifer. Where the beach area has been urbanized or where there is large-scale abstraction from beach zone, groundwater has been contaminated with saline water as there is no fresh water barrier in such locations. Thus, the beach area has, to a large extent, safeguarded the shallow aquifers from serious saline water intrusion in Chennai city. This is a fortuitous situation which also serves as a warning not to urbanise beach zones in coastal cities.
High-resolution 1986 Landsat TM images of the Adriatic coast of Albania have been compared with aerial photographs obtained in 1943, and published literature, in order to decipher the sedimentary architecture and evolution of the late-Holocene deposits of the coastal plain. This coastline is microtidal and dominated by wave action; and abundant sediment is supplied by rivers draining the uplifted mountainous interior of this tectonically active region. The coastal plain has prograded up to 40 km since relative sea level rise slowed down around 6000 years BP. The inland parts of the coastal plain are dominated by parallel storm beach ridges whilst the coastal fringe exhibits a diversity of symmetrical to asymmetrical wave-dominated deltas and spit-deltas encompassing cut-off lagoons. A genetic model to explain the variability of wave-dominated deltas on the Albanian coast is proposed showing a spectrum of forms between prograding symmetrical cuspate deltas formed by bi-directional longshore drift and highly asymmetrical spit-deltas formed by uni-directional longshore drift. Avulsive switching causes abandonment; the symmetrical forms become smoothed out by wave action whereas the spit-deltas become detached barrier beaches that migrate onshore by washover, welding themselves onto the coast. The back barrier cut-off lagoons in this setting have a very low preservation potential. Two much larger lagoons, now partly reclaimed, at Karavasta and Narta, lie within the belt of beach ridges; both have a straight seaward margin parallel to known post-Neogene faulting. The lagoons exhibit differential subsidence which is regarded as neotectonic in origin; the presence of a 60 km long graben or half graben structure linking the two areas of subsidence is suggested to explain the observed phenomena. Subsidence up to 5-10 m is indicated within the last 1,000-2,000 years.
This publication presents a synthesis of technical studies conducted as part of the Medium Size Project (MSP)1 “Identification and Implementation of Adaptation Response Measures in the Drini – Mati River Deltas (DMRD)”, financed by Global Environment Fund (GEF), Albanian Government and United Nations Development Program(UNDP). Both non-technical and technical summaries are presented along with a synopsis of the adaptation measures that have emerged from the project. Institutional and tools and methods using the concept of Integrated Coastal Zone Management (ICZM) are also presented. In summary:• The technical studies were conducted as part of a process to build adaptive capacities in the DMRD to ensure resilience of the key ecosystems and local livelihoods to climate change.• A series of 23 reports related to identification of current climate impacts and its changes in the protected areas within the DMRD, adaptation measures proposed for implementation, including Strategic Climate Change Adaptation, have been drafted. Some other reports, related to potential restoration activities, cost and benefit analysis and integrated management have also been produced.• This report draws out the principle findings of these studies and places them in the overall context of the project objectives.
Project Synthesis Report "Identification and Implementation of Adaptation Response Measures in the Drini – Mati River Deltas". Available from: https://www.researchgate.net/publication/261512637_Project_Synthesis_Report_Identification_and_Implementation_of_Adaptation_Response_Measures_in_the_Drini_-_Mati_River_Deltas [accessed Dec 12 2023].
The small region of Kurbini, situated in the north western part of Albania, faces various hazards, due to the particular geographical position marked by the close neighbourhood of the high mountains and the Adriatic Sea. The hydrological and hydrogeological hazards, the deterioration of the groundwater quality, the intense erosion of the soil, the local acidification/contamination/salinization of the soil, and the desertification of land, are the most important geohazards threatening the area. A complex monitoring of all identified risk factors is necessary in order to avoid catastrophic events and irreversible damages.
The aim of this study is to determine the total concentration and mobility of As in stream sediments samples of four Albanian rivers (Mati, Ishmi, Shkumbini and Semani rivers). Total arsenic and its easily soluble forms have been determined in some sediments samples of 4 different rivers in Albania. Strong digestion methods (using 'aqua regia') were used in our study during the determination of total arsenic. The mobile forms of As were determined after division into fractions, using appropriate chemical reagents such as 25% acetic acid for easy exchangeable As or As adsorbed to carbonates. The distribution of As in rivers sediments is given (As content varied from 10 to 68 mg/kg). ETA-AAS techniques were used for As determination in the laboratory. Due to matrix interferences, direct determination of arsenic in soil samples by AAS-ETA techniques was very difficult. We have used nickel sulphate for matrix stabilisation during the measurements. To increase the range of applicability of this method, the arsenic was separated chemically (extraction technique using toluene extraction method in 10 N HCl solution for As separation as As3+). Arsenic is determined in 1% HNO3 medium and deuterium lamp was used for background correction. The limit of detection was improved and the interferences evidently decreased, but background correction still remained a problem during the determination. The sediments of Mati, Shkumbini, Ishmi and Semani rivers (except Ma3 and Sh3) belong to the second class of quality 'moderately polluted' with As concentration 5-25 mg/kg. The sediments of the sites Ma3 and Sh3 belong to the third class of quality 'markedly polluted' with As.
Interstitial waters from six sites of the Western Mediterranean Basin (Sites 974–979) were analyzed for stable isotopes of dissolved sulfate (δ 34 S, δ 18 O), water (δ 18 O), and dissolved inorganic carbon (13 C), in addition to major and minor ions. Sulfate reduction rates (as determined by modeling sulfate profiles) are positively related to bulk sedimentation rates, which indicates a higher burial of metabolizable organic matter with increasing sedimentation rate. Bacterial sulfate reduction in the deeper samples from Sites 974 and 978 is overprinted by a sulfate input from saline brines located at depth. Dissolution of gyp-sum within the section cored was found at Site 975. The concentration and sulfur isotopic composition of pore-water sulfate (δ 34 S values up to +89‰ relative to the Vienna-Canyon Diablo troilite standard) are dominated by microbial organic matter oxi-dation with associated sulfate reduction. Therefore, most interstitial sulfate is enriched in 34 S with respect to modern Mediterra-nean seawater (δ 34 S = +20.7‰; Site 973 surface seawater). Dissolved sulfate at Sites 974, 975, 977, and 979 is also enriched in 18 O with respect to Mediterranean seawater (δ 18 O[SO 4 2– ] = +9.4‰ relative to Standard Mean Ocean Water). The sulfur and oxy-gen isotopic compositions of dissolved residual sulfate are positively correlated to each other. Microbiologically mediated oxy-gen isotope exchange reactions lead to isotope shifts towards equilibrium between residual sulfate and interstitial H 2 O with increasing degree of sulfate reduction. The results support the previous suggestion that δ 18 O–δ 34 S relations of residual sulfate directly reflect sulfate reduction rates in marine sediments. The depth profiles of the carbon isotopic composition of dissolved inorganic carbonate species (δ 13 C values between –0.1‰ and –22.6‰ relative to the Vienna Peedee Belemnite standard) reflect the in situ degradation of organic matter via sulfate reduction, followed by the formation of methane via in situ fermentation of organic matter, and probably carbonate dissolution and precipitation.
An evaluation is presented of heavy metal pollution, based on statistical analysis of metal concentrations in the sediments from an area along the Albanian Coast. This includes a detailed description of levels of the most important pollutants. Examination of lognormal metal distribution plots indicates that the curve inflections may be operationally used as a threshold between polluted and unpolluted areas. Fe is used for mineralogical normalization of the data. The normalization procedure identifies the most polluted areas. It is clearly demonstrated that some industrial activities such as mining, harbour and chlor-alkali plant, notably affect the heavy metals concentration in the sediments. An evaluation of bakcground levels for the sediments of the Adriatic Albanian coast is also carried out.
The Neotectonic evolution of Albania, from the Middle Pleistocene to the present day, is characterised by a general uplift
that began after the Pliocene. Subsidence took place locally and led to the formation of graben-shaped Quaternary lakes and
plains. During this period, graben lakes were formed at Shkodra, Ohrid, Prespa and Butrinti, whereas at Korça, Elbasani, Zadrima,
Tirana, Myzeqe, etc., graben and graben-like plains were created. The Quaternary subsidence structures can be classified into
two groups: graben structures created by local or regional extension and graben-like structures formed under a compressional
regime. Some case studies are presented to illustrate the formation of these structures and their main engineering geological
and hydrogeological characteristics.
L'évolution néotectonique de l'Albanie, du milieu du Pléistocène aux temps actuels, est caractérisée par un soulèvement général
qui a débuté après le Pliocène. Des épisodes de subsidence ont eu lieu avec formation de structures, de type graben, occupées
par des lacs à Shkodra, Ohrid, Prespa et Butrinti ou des plaines à Korça, Elbasani, Zadrima, Tirana, Myzeqe, etc. . . Ces
structures de subsidence peuvent être classées en deux groupes: des structures de graben créées dans un contexte d'extension
locale et régionale et des structures de graben créés dans un contexte de compression régionale. Quelques études de cas sont
présentées et les caractéristiques hydrogéologiques et de géologie de l'ingénieur de ces secteurs sont précisées.
Saltwater has invaded the coastal aquifer along the southern Adriatic coast of the Po Plain in Italy. The topography, morphology and land use of the region is complex: rivers, canals, wetlands, lagoons, urban, industrial and agricultural areas and tourist establishments all coexist in a small area. Water table and iso-salinity maps show that in four study areas (Ancona-Bellocchio, Marina Romea, San Vitale Forest, Cervia) out of five, the water tables are below sea level and saltwater has replaced freshwater in the aquifer. The fifth area (Classe Forest) has a relatively pristine freshwater aquifer thanks to an average water-table height of 2 m above sea level, a lower hydraulic conductivity (< 7.7 m/day) and a continuous dune system along the coast. Only in this area is the topography high enough to maintain freshwater heads that can counteract saltwater intrusion according to the Ghyben-Herzberg principle. Furthermore, the climate, with an average yearly precipitation of 606 mm and an average temperature of 14.4C, allows for little recharge of the aquifer. Ongoing subsidence, encroachment of sea water along rivers and canals, as well as drainage from agricultural land also enhance the salinization process.
Salalah is situated on a fresh water aquifer that is replenished during the annual monsoon season. The aquifer is the only
source of water in Salalah city. The rainfall and mist precipitation in the Jabal AlQara recharges the plain with significant
renewable fresh groundwater that has allowed agricultural and industrial development to occur. In Salalah city where groundwater
has been used extensively since the early 1980s for agricultural, industrial and municipal purposes, the groundwater has been
withdrawn from the aquifer more rapidly than it can be replenished by natural recharge. The heavy withdrawal of large quantities
of the groundwater from the aquifer has led to the intrusion of seawater. Agricultural activities utilize over 70% of the
groundwater. For the study of the saltwater intrusion, the area has been divided into four strips, A, B, C and D, on the basis
of land-use in the area. Water samples were collected from 18 water wells. Chemical analysis of major ions and pollution parameters
in the groundwater was carried out and compared to the previous observed values. The electrical conductivity and chloride
concentrations were highest in the agricultural and residential strips and Garziz grass farm. Before 1992 the aquifer was
in a steady state, but presently (2005) the groundwater quality in most of the agricultural and residential strips does not
meet drinking water standards. In addition, model simulations were developed with the computer code MODFLOW and MT3DMS for
solute transport to determine the movement of the freshwater/saltwater interface. The study proposes the protection of the
groundwater in Salalah plain aquifer from further encroachment by artificial recharge with reclaimed water, preferably along
the Salalah coastal agricultural strip. This scheme can also be applied to other regions with similar conditions.
The Salalah central sewage treatment plant has been designed to treat 20,000m3/day at the first stage and two further stages to double the initial capacity. The plant currently (2005) treats more than
15,000m3/day effluents to a tertiary level, and after chlorination phase, the effluents are recharged into tube wells in a line parallel
to the coast. The process aims to help stabilize the seawater interface and a part to be recovered from hand-dug wells/boreholes
further inland and downstream. A three-dimensional flow and solute advection transport model was developed to assess the effectiveness
of the proposed recharge scheme and to track the solute transport with respect to the design system. The advection transport
model predicted that in 2020 the maximum pathlines of the injection fluids would reach the abstraction wells that are located
600m, southward of the injection bores in about 1-year travel time in the case of the no-management interference and more
than that southward under management interference. The developed flow predicted the wedge of the saline intrusion in 2019
is tracked up to 2.7 and 3.4km from the shoreline with the injection and without the injection, respectively under constant
underflow. The injection scheme is effective in pushing back the saline zone front by 700m. This study argues that the treated
wastewater would help to increase the water levels at the vicinity of the injection line and to reduce the influence of saline
inflows from the coast. The reclaimed sewage recharge scheme is examined in the case of the Salalah coastal aquifer using
groundwater simulation, which can also be applied to other regions with similar conditions.
Heavy metals (Fe, Mn, Cr, Ni, Cu, Cd, Pb, Sn) concentration has been determined on 39 coastal sediment samples collected in Albania. The relationship between the heavy metals content and the grain size has been considered. All metals, except Cu and Cd, resulted accumulated in the finest fraction, which constituted up to 95% of most of the considered sediments. A good correlation has been found for Ni, Cr, Fe, Zn, Cu in the entire area, indicating a common origin for these metals in the analyzed sediments. Concentration values fall in the range reported for Dinaric chain derived sediments, revealing, generally, a natural origin of the metal contents. Though in some selected areas such as the Drin and the Skumbin Bay, an antropogenic input of Cr, Fe, Ni and Cu can be observed, as the result of discharging of mines and smelter activities.
Land subsidence from deep well pumping has been affecting Bangkok for the past 35 years. Its impact is particularly critical because of the flat low-lying topography and the presence of a thick soft clay layer at the ground surface that augment flood risk and foundation engineering problems, respectively. The subsidence reached its most critical state in the early 1980s when it occurred at a rate as high as 120 mm/year. The rate decreased in the subsequent period but the subsidence-affected area expanded following the growth of the city. Despite various attempts implemented to remedy the crisis, groundwater pumping from the thick aquifer system underneath the city continued to increase from 1.2 million m3/day in the early 1980s to more than 2.0 million m3/day at the turn of the century. Piezometric levels in the main aquifer layers had been drawn down by as much as 65 m. Monitoring data showed a clear correlation between the subsidence and piezometric drawdown. The data suggested that for 1 m3 of groundwater pumped out in Bangkok Plain, approximately 0.10 m3 of ground loss occurred at the surface. Significant development has been made in numerical methods for prediction of differential settlements between building foundations caused by the piezometric drawdown in the aquifers. The strict mitigation measures adopted recently, comprising a pricing policy for groundwater management, an expansion of tap water supply, and strict enforcement of groundwater laws, have resulted in a marked drop in groundwater use. However, the land subsidence will continue for a long while owing to the time-dependent consolidation behavior of the soft clay layer and clay aquitards.
Sea-level change in the Mediterranean Sea during glacial cycles is determined by the temporally variable eustatic change and by the spatially variable glacio-hydro-isostatic response of the earth and ocean to the growth and decay of ice sheets. Superimposed upon this are the relative changes from any vertical tectonic movement of the land. For sites that are either tectonically stable or where the magnitude of tectonic uplift is known, comparisons of observed change with predictions of the glacio-hydro-eustatic signals provide constraints on the earth–ice parameters used. The resulting predictive models can then be used to interpolate sea-level change and shoreline migration between the spatially and temporally limited observational data set. Whether such parameters reflect the true properties of the mantle and ice sheets depends on whether an effective separation has been achieved from the inversion of the observational data set. This paper explores this issue and demonstrates that observations from certain regions in the Mediterranean are particularly important in effecting the separation. This is supported by a trial analysis of a small observation data set from sites that exhibit some of the desirable features of an ideal data set. Basin-wide predictions of sea-level change, palaeo-water depth and shoreline locations based on these analyses are presented for selected epochs.
There is growing research interest in the ethnobiology, socio-economics and management of mangrove forests. Coastal residents who use mangroves and their resources may have considerable botanical and ecological knowledgeable about these forests. A wide variety of forest products are harvested in mangroves, especially wood for fuel and construction, tannins and medicines. Although there are exceptions, mangrove forest products are typically harvested in a small-scale and selective manner, with harvesting efforts and impacts concentrated in stands that are closer to settlements and easiest to access (by land or by sea). Mangroves support diverse, local fisheries, and also provide critical nursery habitat and marine productivity which support wider commercial fisheries. These forests also provide valuable ecosystem services that benefit coastal communities, including coastal land stabilization and storm protection. The overlapping of marine and terrestrial resources in mangroves creates tenure ambiguities that complicate management and may induce conflict between competing interests. Mangroves have been cut and cleared extensively to make way for brackish water aquaculture and infrastructure development. More attention is now given to managing remaining forests sustainably and to restoring those degraded from past use. Recent advances in remotely sensed, geo-spatial monitoring provide opportunities for researchers and planners to better understand and improve the management of these unique forested wetlands.
137Cs activity concentrations were studied in the sediment profiles collected at five locations in the Middle and South Adriatic.
In the sediment profiles collected from the South Adriatic Pit, the deepest part of the Adriatic Sea, two 137Cs peaks were identified. The peak in the deeper layer was attributed to the period of intensive atmospheric nuclear weapon
tests (early 1960s), and the other to the Chernobyl nuclear accident (1986). Those peaks could be used to estimate sedimentation
rates by relating them to the respective time periods. Grain-size analysis showed no changes in vertical distribution through
the depth of the sediment profile, and these results indicate uniform sedimentation, as is expected in deeper marine environments.
It was not possible to identify respective peaks on more shallow locations due to disturbance of the seabed either by trawlers
(locations Palagruža and Jabuka) or by river sediment (location Albania). The highest sedimentation rates were found in Albania
(∼4 mm y−1) and Jabuka (3.1 mm y−1). For Palagruža, the sedimentation rate was estimated to be 1.8 mm y−1, similar to the South Adriatic Pit where the sedimentation rate was estimated to be 1.8±0.5 mm y−1. Low sedimentation rates found for the Middle and South Adriatic Sea are consistent with previously reported results for
the rest of the Mediterranean.
Published and new sea level data are used to provide projections of sea level change in Italy for the year 2100 by adding new isostatic and tectonic component to the IPCC and Rahmstorf projections. Comparison of the observations from more than 130 sites (with different geomorphological and archaeological sea level markers) with the predicted sea level curves provides estimates of the vertical tectonic contribution to the relative sea level change. The results are based on the most recent ANU model for the ice sheets of both hemispheres, including an alpine deglaciation model. On the basis of the eustatic, tectonic and isostatic components to the sea level change, projections are provided for marine inundation scenarios for the Italian coastal plains for the year 2100, that today are at elevations close to current sea level.
Scientific information on affecting degree by heavy metals of sediments from Fani and Mati rivers (northern Albania) is limited. In this study, the sediment samples taken from these rivers, and ore and calcine samples taken from the industrial sites located within the basins of these rivers were analyzed by atomic absorption spectrometry for Cd, Pb, Zn, Cu, Cr, As and Ni, to determine the enrichment of these elements. The results indicated that the sediment samples contained up to 736 mg/kg Ni, 618 mg/kg Zn, 26.1 mg/kg Pb, 0.83 mg/kg Cd, 1167 mg/kg Cu, 408.7 mg/kg As, and 375.8 mg/kg Cr. The highest metal concentrations are found in sediments collected below the Rubiku and Kurbneshi sites. Although the data exhibited significant dilution of some heavy metals in sediments from downstream, the concentrations of Cr, Ni, Zn and Cd exceed the values at the 90th percentile, while the concentrations of Cu and As exceed the maximum values (Geochemical Atlas of Europe). The ore and calcine leachates contained up to 16800 mg/kg Cu, 53 mg/kg Ni, 81 mg/kg Zn and 0.31 mg/kg Cd, suggesting that the existing wastes contain soluble copper, zinc, nickel and cadmium. The risk of heavy metals in the environment is high because of the elevated levels of Cr, Ni, Cu, Zn, As and Cd in the river sediments. The results indicate downstream transference of these metals from the studied sites.
Though India is blessed with good rainfall, large amount of it is lost through runoff and it cannot be impounded on the surface for want of suitable sites for storage. The varied hydrogeologic conditions prevalent prevent rapid infiltration into groundwater reservoirs. There is thus an imbalance between recharge and groundwater development in many parts of the country. The over-extraction of groundwater resources has affected the agricultural economy and has caused serious shortage of water for drinking. It is imperative that runoff which is going waste should be harvested and utilised for recharging depleted aquifers. Realising this many artificial recharge projects have been taken up by the Central and State Groundwater Departments. There are other agencies who have come up with methods for recharging depleted aquifers. Results obtained are impressive.
Charnockites of the southern-central part of the Indian peninsula are commonly weathered into Vertisols containing gypsum concretions. Sulphur in the concretions as well as sulphur in atmospheric deposition and in groundwater was investigated by means of sulphur isotopic analysis. The isotopic ratios in the gypsum fall in the same range as those in atmospheric deposition suggesting that the sulphate is of atmospheric origin brought in by the strong monsoonal winds.The deposition contains, along with the seawater sulphate, a reduced sulphur component possibly emanating from dimethyl sulphide or H2S. Another major sulphate source in the studied area is ammonium sulphate used as nitrogenous fertilizer. The mobilization of sulphur through bedrock weathering is negligible. -from Authors
The following paper is a summary of sedimentological data on the Adriatic Sea (with the exception of the areas along the Jugoslavian and Albanian coasts). Because it is difficult to summarize a summary, only a few of the main conclusions will be mentioned here.
Geophysical investigations indicate that the top of the limestone series, underlying the clayey and sandy deposits of the Pliocene and the Quaternary in the Adriatic area has a very uneven topography. Its greatest depths (4–6 km) are found a) between Ravenna and Rimini, b) between San Benedetto and Pescara, and c) below the Albanian shelf.
Recent sands are mainly limited to the littoral zone; pleistocene sand, originally supplied by rivers, covers the greater part of the deeper shelf. Between these zones a terrace-shaped pro-littoral mud belt is present, where the bulk of the recent terrigenous mud is deposited. The maximum rate of accumulation in this belt is probably about 4 1/2 mm per year.
The remaining part of the recent mud is transported in the sea water as floccules of such small size that they remain suspended over the deeper zones of the shelf. Most of it is deposited in the basins of the Central Adriatic (maximum accumulation rate for the Holocene on the average circa 1/2 mm per year) and in the bathyal basin in the southeast. The deepest area of the latter basin is formed by an almost horizontal plain (circa 1218 m deep). The longest core from this plain (240 cm of Holocene and 400 cm of late Pleistocene) is composed for roughly 61% of turbidite material, 5% of volcanic ash (coarser than fine silt), 0,2% of organic carbonate remains (coarser than silt) and 34% of normal terrigenous mud. The ash falls were limited to the central and southeastern parts of the Adriatic.
The oxygen and carbon stable isotope compositions of the present-day Mediterranean waters have been measured in order to evaluate their variability, which is related to the specific climatic and hydrological conditions within the basin. The experimental equation between the δ18O value and the salinity of water, based on 300 measurements on surface, intermediate, and deep waters sampled during the VICOMED 2 and 3 cruises in the western, central and eastern Mediterranean, has a slope of 0.27, a value which is significantly lower than the slope of 0.45, as defined in the northeast Atlantic Ocean. This difference in the δ18O–salinity relationship, which occurs immediately in the Alboran basin, is basically a characteristic of the climatic regime of the Mediterranean, i.e., of an excess evaporation over fresh water input. The largest variations of these two parameters, δ18O of water and δ13C of ∑CO2, are observed in the surface waters, mostly in the western Mediterranean. This evolution mirrors the progressive eastward restriction, which separates the less-evaporated and more-productive western basins from the more-evaporated and less-productive eastern basins. The intermediate waters constitute a homogeneous layer. However, their δ18O values decrease eastward by 0.35‰ at maximum, due to progressive dilution by mixing with overlying and underlying water masses; their δ13C values decrease also eastward by 0.35‰ at maximum, due to an increasing input of nutrients issued from the regeneration of sinking organic particles. The deep waters have similar δ18O values but slightly higher δ13C values (often by less than 0.1‰) than the overlying intermediate waters, indicating generally well ventilated conditions due to active winter convection.
Arsenic (As) and selenium (Se) have become increasingly important in
environmental geochemistry because of their significance to human
health. Their concentrations vary markedly in the environment, partly in
relation to geology and partly as a result of human activity. Some of
the contamination evident today probably dates back to the first settled
civilizations which used metals.Arsenic is in group 15 of the periodic
table (Table 1) and is usually described as a metalloid. It has only one
stable isotope, 75As. It can exist in the -III, -I, 0, III, and V
oxidation states (Table 2).
Composite monthly samples of atmospheric precipitation were collected over different periods of time ranging from one to seven years at 77 different locations throughout Italy. These samples were measured for their oxygen and hydrogen isotopic composition to obtain basic information for hydrological and meteorological studies in this area. On the basis of the results obtained a first map of the isotopic composition of precipitations in Italy has been drawn up. The main features of this map are the following: (1) no isotopic latitudinal gradient has been found along the Tyrrhenian coast from Sicily to the Italian–French border, despite the considerable range of latitude; (2) a minor latitudinal gradient is found in the southeasternmost section of the country (Apulia), partially favored by the local morphology; (3) a marked ‘shadow effect’ of the Apennines is apparent along the southern section of the Po valley and along the central section of the Adriatic coast; (4) the contribution of water vapor from the northernmost section of the Adriatic sea affects the eastern and central sections of the Po plain; (5) the shadow effect of the Alps is considerably smaller than expected; (6) the isotopic vertical gradients calculated in nine different areas and based on groups of two to five different stations vary but are essentially close to about −0.2‰/100m; (7) when mean monthly temperature values were available, their relationship with the isotopic composition of precipitation was found to be, on average, very poor; (8) the relationship between mean δ18O and mean δD calculated for the collection locations shows shifts of both the slope and the deuterium excess when compared to the global meteoric water line. These shifts are different for northern, central, and southern Italy; (9) in a few cases anomalously low monthly δ values suggest the existence of pronounced ‘amount effects’.
Individual and monthly precipitation samples from the polluted atmosphere of Bologna (Emilia-Romagna province) were collected during March 1996 to May 1997 and analyzed for major ions in solution and S isotopes in dissolved SO4. Weighted mean enrichment factors relative to seawater are found to be 1.0 for Na, 15.2 for K, 105 for Ca, 3.3 for Mg, 17.3 for SO4 and 663 for HCO3-. Very good positive correlations are observed for the Ca2+-Mg2+-HCO3--SO42--NO3- system, indicating that dissolution of Ca (+/-Mg)-carbonate particles by H2SO4 and HNO3 from combustion of oil and gas is a major process controlling the chemical composition of rain and snow. Na+ and Cl- in monthly precipitation derive essentially From sea spray, but the contribution of Na+ from continental sources is appreciable in a number of individual rains. NH4+ appears to be on average more abundant in spring and summer precipitation, its main sources bring microbial activity in soils and application of fertilizers. K+ is probably of continental origin from soil dust. The S isotopic composition of SO4 is systematically positive, with mean delta(34)S values of + 3.2 +/- 1.6 parts per thousand (n = 40) in individual precipitation and + 2.8 +/- 1.4 parts per thousand (n = 12) in monthly precipitation. These isotopic compositions are interpreted in terms of a dominant contribution of S From anthropogenic emissions and subordinate contributions from biogenic and marine sources. Pollutant SO4 is estimated to have a delta(34)S value in the range + 2.5 to + 4.5 parts per thousand, whereas a distinctive delta(34)S of -4.5 parts per thousand or lower indicates SO4 from oxidation of biogenic gases. The isotopic and chemical compositions of SO4 do not depend on wind direction, thus testifying to a mostly local source for pollutant S in the Bologna atmosphere.
Arsenic contamination in groundwater used for drinking purposes has been envisaged as a problem of global concern. Exploitation of groundwater contaminated with arsenic within the delta plains in West Bengal has caused adverse health effects among the population within a span of 8-10 years. The sources of arsenic in natural water are a function of the local geology, hydrology and geochemical characteristics of the aquifers. The retention and mobility of different arsenic species are sensitive to varying redox conditions. The delta plains in West Bengal are characterized by a series of meander belts formed by the fluvial processes comprising different cycles of complete or truncated fining upward sequences (sand-silt-clay). The arseniferous groundwater belts are mainly located in the upper delta plain and in abandoned meander channels. Mineralogical investigations have established that arsenic in the silty clay as well as in the sandy layers occurs as coatings on mineral grains. Clayey sediments intercalated with sandy aquifers at depths between 20 and 80 m are reported as a major source of arsenic in groundwater.Integrated knowledge on geological, hydrologicaland geochemical characteristics of the multi-level aquifer system of the upper delta plain is therefore necessary in predicting the origin, occurrence and mobility of arsenic in groundwater in West Bengal. This would also provide a basis for developing suitable low-cost techniques for safe drinking water supply in the region.
In this study, the biogeochemical transformations of sulphur in organic-rich marine sediments in a Scottish fjord are investigated by a combination of pore water and sediment geochemistry with sulphide diffusive gradient thin-film probes and sulphate isotopic data (δ34S and δ18O). Particular attention is paid to sulphur cycling in the upper sediment profile where sulphate reduction occurs but free sulphide is below the detection limits of conventional pore water geochemical analysis but quantifiable by sulphide diffusive gradient thin film. In the uppermost part of the sediment core, δ18O sulphate decreased from near-sea water values to +7‰, indicating that anoxic sulphide oxidation dominated during this interval. Sulphate δ34S remained unchanged as there was no net sulphate reduction (i.e. reduction was balanced by re-oxidation). Below 4 cm depth, there was a slight increase in sulphate δ34S from 20‰ to 23‰ associated with minor accumulation of iron sulphide. The δ18O of the sulphate also increased, to around +10‰ at 10 cm depth, as a result of the isotopic exchange of sulphate–oxygen with pore water and/or sulphur disproportionation reactions mediated during sulphur cycling. These processes continued to increase the δ18O of the sulphate to 14‰ at 20 cm depth with no further change in the δ34S of the sulphate. Below 20 cm depth, free sulphide is detectable in pore waters and both the δ34S of the sulphate and sulphide increase with depth with an offset controlled by kinetic fractionation during bacterial sulphate reduction. The δ34S of the sedimentary organic fraction shifted towards lower, more bacteriogenic, values with depth in the profile, without any increase in the size of this sulphur pool. Thus, the organic sulphur fraction was open to interaction with bacteriogenic sulphide without the occurrence of net addition. Therefore, caution should be exercised when using sulphur isotopic compositions to infer simple net addition of bacteriogenic sulphide to the organic sulphur fraction.
The combination of the mountainous terrain of Albania and a seasonally wet Mediterranean climate has led to some of the most extreme erosion in Europe. New methodology is used in this work to estimate soil erosion risk and provide a framework for soil conservation that can effectively and economically control soil loss. A one-dimensional hydrology, vegetation and erosion model (RDI/CSEP) is used to calculate accumulative soil erosion. This model provides an integrating the climatic, topography and associated vegetation components into soil erosion modeling. The forecast runoff, accumulated across the frequency distribution of storms, is used to give a climatic potential, which is then appropriately combined with measures of topography and soil erodibility to estimate the expected rate of soil erosion at a resolution of 1 km. Annual and monthly soil erosion maps of Albania are also developed in this research. The proposed approach for evolution and mapping soil erosion by water uses existing soil maps, land use maps, a digital elevation model (1 km), and interpolated climate data. The erosion maps clearly show that Albania is a country where erosion is potentially severe. The annual erosion rates are estimated at 10 t ha –1 y –1 or more, especially in the south and center part of the country. In three areas (two in Gjirokastër, and one in Sarandë) the annual erosion rate is more than 100 t ha –1 y –1 . Erosion rates are highest in October, November, February and December and lowest in June and July.
Chemical analyses of wells penetrating the coastal aquifer of Israel indicate that the relative concentrations of sodium, calcium, magnesium, bicarbonate, and hydrogen species deviate considerably from the ideal mixing line between fresh water and sea water, as represented by the concentration of chlorides. Furthermore, deviation patterns were found to be distinctly different for areas of present sea-water intrusion, and areas from which ancient brines are still flushed. These differences, explainable in major part as the combined effects of cation exchange and carbonate equilibria, can in turn be utilized to distinguish between invading and retreating saline-water bodies, and identify their existence at the very beginning of the salinization process. Observed patterns are verified here in major part, with the aid of a single-cell simulation model.
It has generally been recognized that molecular diffusion can be a significant process affecting the transport of carbon-14 in the subsurface when occurring either from a permeable aquifer into a confining layer or from a fracture into a rock matrix. An analytical solution that is valid for steady-state radionuclide transport through fractured rock is shown to be applicable to many multilayered aquifer systems. By plotting the ratio of the rate of diffusion to the rate of decay of carbon-14 over the length scales representative of several common hydrogeologic settings, it is demonstrated that diffusion of carbon-14 should often be not only a significant process, but a dominant one relative to decay. An age-correction formula is developed and applied to the Bangkok Basin of Thailand, where a mean carbon-14-based age of 21,000 years was adjusted to 11,000 years to account for diffusion. This formula and its graphical representation should prove useful for many studies, for they can be used first to estimate the potential role of diffusion and then to make a simple first-order age correction if necessary.
This article presents results on heavy metal (Fe, Mn, Cr, Ni, Cu, Cd, Pb and Zn) speciation in the coastal sediments of Albania. Sediment samples were collected within the framework of the activities of the Interreg Italia-Albania Project, carried out in the Southern Adriatic Sea in 2000-01. This study shows that Albanian coastal sediments are highly influenced by river input, as the decreasing concentrations from coast to offshore confirm. Pb represents an exception of the general trend; meteoric inputs are prevalent for this metal. Ni, Cr, Fe, Zn and Cu correlate significantly and positively in the entire area, indicating a common origin for these metals in the analyzed sediments. All metals result mostly associated to the most refractory phases, which constitute up to 80% of the total concentration. Nevertheless a recent input of Cr, Ni, Cu and Mn can be observed, as the result of mining and industrial activities, in some selected areas, such as the Drin Bay and Durres. Their high concentration in the bioavailable phase can determine toxic effect upon biota.
Elevated biogenic SO2 from the oxidation of dimethylsulphide (DMS) in the marine atmosphere was measured over the North Atlantic Ocean in spring and summer 2003. Stable isotope apportionment was used to distinguish between anthropogenic and biogenic SO2 in the marine atmosphere south of Greenland. Atmospheric DMS measurements were within range of previous studies. Biogenic SO2 concentrations were as high as 82 nmol m−3 (spring geometric mean: 4 nmol m−3, σ = 17; summer geometric mean 7 nmol m−3, σ = 19) and are the highest reported values for marine biogenic SO2 in the literature. Elevated biogenic SO2 was found in air masses influenced by anthropogenic pollutants during the summer. This indicates that anthropogenic pollutants may affect the fate of oceanic emissions of sulphur compounds in the atmosphere favoring the formation of cloud condensation nuclei.
Environmental isotopes (²H, ¹⁸O, ³H, ¹³C, ¹⁴C, ³⁴S), in conjunction with hydro-geological and hydro-chemical data, were employed to understand the groundwater recharge processes and hydrodynamics of the Tiruvadanai aquifers in the Tamilnadu State in Southern India. Hydro-chemical characterisation of the groundwater indicated that the Tertiary aquifers (depth: 50–200 m, un-confined/semi-confined/confined), contain no-dominant (Ca–Mg–HCO3–Cl) to brackish (Na–Cl) type of waters and the deeper (350–500 m) Cretaceous aquifer (confined) contains freshwater. The concentration of various chemical species along the general groundwater flow direction (northwest to east) showed a trend with decrease in Mg²⁺ and Ca²⁺ and an increase in Na⁺ and K⁺ in both Tertiary and Cretaceous aquifers which is also indicated by decreasing saturation index values for dolomite along the flow path. This could be attributed to ion-exchange processes. A higher pH value of Cretaceous aquifer samples (7.4–8.6) could also be responsible for the lowering of Mg²⁺ and Ca²⁺ concentrations by facilitating precipitation of carbonates in them.
An assessment is made of contemporary effective sea-level rise (ESLR) for a sample of 40 deltas distributed worldwide. For any delta, ESLR is a net rate, defined by the combination of eustatic sea-level rise, the natural gross rate of fluvial sediment deposition and subsidence, and accelerated subsidence due to groundwater and hydrocarbon extraction. ESLR is estimated under present conditions using a digital data set of delta boundaries and a simple model of delta dynamics. The deltas in this study represent all major climate zones, levels of population density, and degrees of economic development. Collectively, the sampled deltas serve as the endpoint for river basins draining 30% of the Earth's landmass, and 42% of global terrestrial runoff. Nearly 300 million people inhabit these deltas. For the contemporary baseline, ESLR estimates range from 0.5 to 12.5 mm yr− 1. Decreased accretion of fluvial sediment resulting from upstream siltation of artificial impoundments and consumptive losses of runoff from irrigation are the primary determinants of ESLR in nearly 70% of the deltas. Approximately 20% of the deltas show accelerated subsidence, while only 12% show eustatic sea-level rise as the predominant effect. Extrapolating contemporary rates of ESLR through 2050 reveals that 8.7 million people and 28,000 km2 of deltaic area in the sample set of deltas could suffer from enhanced inundation and increased coastal erosion. The population and area inundated rise significantly when considering increased flood risk due to storm surge. This study finds that direct anthropogenic effects determine ESLR in the majority of deltas studied, with a relatively less important role for eustatic sea-level rise. Serious challenges to human occupancy of deltaic regions worldwide are thus conveyed by factors which to date have been studied less comprehensively than the climate change–sea-level rise question.
This study summarizes the arsenic (As) concentration in soils in the vicinity of the sulfide mining areas as well as in four Albanian rivers (e.g., Mati, Ishmi, Shkumbini and Semani) sediments to understand the behavior, speciation and mobilization of As in soils and sediment compartments. Arsenic concentration in soils in the mining areas ranged from 50 to 300 mg/kg, whereas in Korca areas (815 ha) where different fruit plants grow, As concentration varied between 4 and 25 mg/kg. Arsenic concentration and its mobilization in river and stream sediments were also investigated. It was noted that sediments collected from the four investigated river sites contained As at 10–68 mg/kg. The mobile forms of As were determined after division into fractions, using appropriate chemical reagent such as 25% acetic acid, for easily exchangeable As or As adsorbed to carbonates. Different analytical techniques such as atomic absorption spectroscopy hydride generation techniques and atomic absorption spectroscopy electro-thermal atomization techniques were also used in our present study.
Ophiolites of the Balkan Peninsula, of Upper Jurassic to Lower Cretaceous age, extend through the Mirdita zone (Albania) to the Pindos and Othrys complexes southern (Greece), and host massive sulfide deposits of Cu–Zn–(Pb) type. The deposits in Albania are hosted in intermediate to felsic-dominated volcanic successions of considerable thickness. These deposits are associated with ophiolites that were formed during the initial stages of an intra-oceanic westward-dipping subduction zone (arc, fore-arc, back-arc setting), and most closely resemble polymetallic sulfide deposits associated with felsic volcanic rocks at the modern seafloor. The massive sulfide ores are comprised of pyrite, chalcopyrite and lesser amounts of sphalerite, and are characterized by an increasing content of Au, Ag, As, Se, Sb, Mo and Hg from the Othrys to Pindos and Mirdita (Munella) ophiolites. In addition, the concentrations of these elements in both massive sulfide ores and Fe–Cu–Ni–Co type ores are higher in the Pindos compared to those in the Othrys complex.
Research carried out since the opening of Albania to the ‘western’ geological community in the 1990s allows the geology and tectonics of this small Balkan country to be integrated into an overall interpretation of Neotethys in the Eastern Mediterranean region, specifically Greece and the former Yugoslavia region. Albanian geology is most famous for the occurrence of contrasting ophiolites of Jurassic age. The country is sub-divided into three main geotectonic units. Those in the west (i.e. Sazani, Ionian, Kruja, Krasta–Cukali and the Albanian Alps) relate to the western margin of Apulia, effectively part of North Africa from Early Mesozoic time onwards. In the east is the Korabi zone, interpreted as a microcontinent located further northeast within Neotethys. Between the two is the Mirdita zone, dominated by two contrasting Jurassic ophiolites: the ‘Western-type’ ophiolite and the ‘Eastern-type’ ophiolite.
Arsenic enrichment of groundwater in the Red River (Song Hong) delta in Vietnam was discovered in 1998. Several studies performed in this area found concentrations of As exceeding the WHO-guideline of 10 μg/L. This study focuses on an area south of Hanoi city, Nam Du, where a new well field came into operation in 2004. The new well field is situated on the bank along the Red River in order to facilitate induced infiltration. The Nam Du area receives surface water with a high load of nutrients and organic matter from the Hanoi sewage system, and is subject to recently increased groundwater extraction from the Pleistocene aquifer system. The objective of the study was (1) to assess the situation in the Nam Du area by mapping the distribution of As, (2) to identify possible sources of As in the groundwater and (3) to investigate the mobilisation processes releasing As into the groundwater. Two main field campaigns were carried out, in 2006 and 2007, both during the dry season. Groundwater and surface water levels were measured and water- and sediment samples were collected. The water in the Pleistocene aquifer shows the same water-level variations as the Red River at a distance of 2.5 km from the riverbank, while the Holocene aquifer heads are recharged by surface water ponds and show less seasonal variation. The concentration of As in the groundwater in Nam Du exceeded the WHO provisional guideline value at all sampled locations. The main conclusions are summarised as (i) the distribution of As is highly variable but the zones with the highest concentrations of As are near the Red River in the Holocene aquifer and just down gradient from this in the Pleistocene aquifer, (ii) the sediments within the aquifers are considered to be the source of the As, where the Holocene aquifer is believed to act as the main source of As into the Pleistocene aquifer as reduced groundwater containing As from the Holocene aquifer is flowing downwards due to the downward gradient, and (iii) two different processes appear to take part in the mobilisation process. In the Holocene aquifer, reductive dissolution of FeOOH and the release of adsorbed As appear to be the main mobilisation processes. In the Pleistocene, however, mobilisation of adsorbed As due to competition from ions for surface sites on FeOOH may be a major mechanism of As mobilisation. It is suggested that the drinking water supplier undertakes the following actions to ensure acceptable levels of As in the treated drinking water: (a) to implement a long-term monitoring program, (b) implement alternative treatment technologies; and (c) to possibly consider an alternative drinking water source.
Sediment core palaeomagnetic and mineral magnetic records from two crater lakes in central Italy and from the western margin of the Adriatic Sea have been used to evaluate local and regional responses to Holocene environmental change. In all cores, sediment magnetism reflects the interplay between catchment material and the in situ production of bacterial magnetite (magnetotactic bacteria). In the lakes, the earliest Holocene sediments record a waning catchment input that we attribute to rising lake levels and increased tree cover in the catchment. From ∼9000 to 5000 yr BP, both lakes become anoxic, a consequence of water-mass stratification driven by high lake levels. Bottom-water anoxia also developed in the Adriatic, with sapropel S1 produced between ∼9000 and 7000 yr BP. Subsequently, the lake and Adriatic mineral magnetic records show evidence for increased catchment delivery, consistent with pollen evidence for Bronze Age deforestation. In the lakes, this evidence is first recorded at ∼4300 yr BP and a number of distinct clearance events are recorded. In comparison, at Adriatic site RF93-30, lithogenic input increases abruptly at ∼3500 yr BP and is followed by a slowly changing record of waxing and waning sediment delivery.Inter-site comparisons of palaeomagnetic data point to a possible link between the magnitude of the bacterial magnetite component and the recorded magnetic inclination. The sites are at near identical latitudes and have similar sediment accumulation rates but the Adriatic sites have a core-average magnetic inclination that is some 10° steeper than the lake average values. We suggest that the large dipole moment of the magnetosome chains, which in life produce the passive alignment of the bacterium along the local geomagnetic field line, produce a more faithful (albeit smoothed) record of the geomagnetic field.
The rare earth pattern in sedimentary rocks is nearly constant and is considered to represent the relative abundances of these elements in the continental crust. This pattern is derived principally from mixing of basic and acidic igneous rock patterns. Preliminary calculations indicate that approximately equal contributions of basic and acid patterns are required to give the observed rare earth abundance pattern in sedimentary rocks.A table of element abundances in the continental crust, calculated on the basis of a 1:1 mixture of granite and basalt abundances, is presented. Attention is drawn to differences from previous estimates.
We provide new data on relative sea-level change from the late Holocene for two locations in the central Mediterranean: Sardinia and NE Adriatico. They are based on precise measures of submerged archaeological and tide notch markers that are good indicators of past sea-level elevation. Twelve submerged archaeological sites were studied: six, aged between 2.5 and 1.6 ka BP, located along the Sardinia coast, and a further six, dated ∼2.0 ka BP, located along the NE Adriatic coast (Italy, Slovenia and Croatia). For Sardinia, we also use beach rock and core data that can be related to Holocene sea level. The elevations of selected significant archaeological markers were measured with respect to the present sea level, applying corrections for tide and atmospheric pressure values at the time of surveys. The interpretation of the functional heights related to sea level at the time of their construction provides data on the relative changes between land and sea; these data are compared with predictions derived from a new glacio–hydro-isostatic model associated with the Last Glacial cycle. Sardinia is tectonically relatively stable and we use the sea-level data from this island to calibrate our models for eustatic and glacio–hydro-isostatic change. The results are consistent with those from another tectonically stable site, the Versilia Plain of Italy. The northeast Adriatic (Italy, Slovenia and Croatia) is an area of subsidence and we use the calibrated model results to separate out the isostatic from the tectonic contributions. This indicates that the Adriatic coast from the Gulf of Trieste to the southern end of Istria has tectonically subsided by ∼1.5 m since Roman times.
We discuss the palaeoclimatic interpretation of unprecedented high-resolution micropalaeontological studies of short-term (2 to 4 centuries) interruptions within early Holocene organic-rich layer (sapropel) S1 from the eastern Mediterranean. Results for cores from the Adriatic and Aegean seas that contain `double' S1 sapropels indicate that these interruptions, which are centred roughly around 7000 years 14Cnc BP, are genuine and related to climatic deterioration. This interpretation is endorsed by a coeval dry event recorded in terrestrial records and indications of climatic deterioration affecting human migration patterns and early societies in Egypt. The presence of sapropel interruptions in the two major source areas of deep water for the entire eastern Mediterranean likely implies that similar intervals may be found throughout the basin, provided that sedimentation rates and sampling resolutions allow the detection of events with a duration of only several centuries. Moreover, our results show that the `sapropel mode' of circulation comprises a delicate balance between reduced ventilation and enhanced productivity, which is easily disturbed through surface water cooling triggering a short time of improved deep water ventilation.
Chromium ore was treated to produce ferrochromium from 1979 until 2000 in a smelter in Burrel, 35 km NE of Tirana (Albania). As a consequence, large amounts of solid waste, i.e. slags (about 9.106 m3) have been disposed next to the smelter, disfiguring the landscape. In an attempt to define contaminated sites, heavy metal content of the different sampling media have been compared with respective background samples.In the study area, the determination of background values in soil samples is complicated due to the different geological substrates. Cr and Ni background concentrations in serpentinite-derived soils, west of the smelting plant, are markedly higher than in the Pliocene gravel/sandy soils, where the smelter is situated (Cr 2147 and 193 mg/kg, respectively; Ni 2356 and 264 mg/kg). These values are clearly lower than those encountered around the smelter. Average total Cr and Ni concentrations in soils around the smelter are 3117 and 1243 mg/kg, respectively. The highest concentrations of Cr (up to 2.3 wt.%), were recorded in samples taken near the smelting compartment within the industrial plant and next to the slags clearly indicating that the smelter forms a point source of Cr contamination. The Cr / Fe ratio is the best indicator to differentiate non-polluted (Cr / Fe Serpentinite soil: 130–390; Pliocene soils: < 130) from polluted areas (> 390 smelting nearby of the slags).Cr and Ni values for local backgrounds in stream and overbank sediments were taken in the Mat river 6 km upstream and to the east of the smelter (268 and 430 mg/kg for Cr, and 306 and 604 mg/kg for Ni, respectively). Equivalent sediments taken from the Zalli i Germanit river, which drains the smelter area are respectively 816 and 1126 mg/kg for Cr and 1115 and 1185 mg/kg for Ni.Dust samples, taken from the lofts of houses up to 2 km from the smelter, display high concentrations of Cr, Ni and Zn (average contents of 2899, 436 and 902 mg/kg, respectively). The later concentrations in the dust samples have been confirmed by mineralogical analysis where Cr-bearing mineral phases such as ferrochromium and chromium oxides, clearly relate to the activity of the smelter. Consequently, atmospheric deposition of dust particles forms a serious problem and can also be responsible for the elevated contents encountered in soil samples around the smelter.All these data show that the degree of contamination caused by industrial activity of the Burrel Cr-smelter is severe, although no Cr(VI) was detected in soil water extractions nor in the surface or groundwater where concentrations were < 0.01 mg/kg.
The stable isotopic composition of hydrogen and oxygen (δ2H and δ18O) and tritium activity (3H) were monitored in monthly precipitation at two continental stations (Ljubljana, Zagreb) and six stations along the eastern Adriatic coasts of Slovenia and Croatia in the period 2001–2003. Mean air temperatures and amount of precipitation were also recorded.Distinct differences in both meteorological and isotopic data between the continental and maritime stations were observed. Seasonal variations in δ18O are smaller at the maritime stations than at the continental ones due to smaller seasonal temperature variations. A good correlation between δ18O and δ2H was obtained for each station, and the local meteoric water lines are close to the Global Meteoric Water Line, with a decreasing trend of slope for the south-Adriatic stations. Good correlations between δ18O in monthly precipitation and mean monthly air temperature were observed at all stations. The slope of δ18O vs. T varied between 0.37‰ °C−1 and 0.15‰ °C−1. Mean 3H activity and seasonal variation of 3H activity are smaller at maritime stations than at continental ones. Additionally, 3H activity decreases in the NW–SE direction of the Adriatic coast.The study of spatial variations over this relatively small area rich in geographical and climatic diversities showed the complexity of the isotopic composition of precipitation and the isotopic data obtained for eight stations, most of them in the karstic area along the Adriatic coast, and gave valuable information for regional hydrological investigations and modelling of isotope variability over the Mediterranean basin.
The coastal plain bordering the southern Venice Lagoon is a reclaimed lowland characterized by high subsidence rate, and ground level and water-table depth below sea level. In this agricultural region, where the surface hydrologic network is entirely artificially controlled by irrigation/drainage canals, salinization problems have long been encountered in soils and groundwaters. Here we use isotopic and geochemical tracers to improve our understanding of the origin of salinization and mineralization of the semi-confined aquifer (0–40 m), and the freshwater inputs to this hydrological system. Water samples have been collected at different seasons in the coastal Adriatic Sea, lagoon, rivers and irrigation canals, as well as in the semi-confined aquifer at depths between 12 and 35 m (14 boreholes), and in the first confined aquifer (three boreholes drilled between 40 and 80 m depth). Stable isotopes (δ¹⁸O and δD) and conductivity profiles show that direct saline intrusion from the sea or the lagoon is observed only in a restricted coastal strip, while brackish groundwaters are found over the entire topographic and piezometric depression in the centre of the study area. Fresh groundwaters are found only in the most western zone. The sharp isotopic contrast between the western and central regions suggests disconnected hydrological circulations between these two parts of the shallow aquifer. The border between these two regions also corresponds to the limits of the most strongly subsiding zone.
This study proposes a hydrogeochemical tool to distinguish between salinization and freshening events of a coastal aquifer and quantifies their effect on groundwater characteristics. This is based on the chemical composition of the fresh-saline water interface (FSI) determined from combined field work, column experiments with the same sediments, and modeling. The experimental results were modeled using the PHREEQC code and were compared to field data from the coastal aquifer of Israel. The decrease in the isotopic composition of the dissolved inorganic carbon (delta(13)C(DIC)) of the saline water indicates that, during seawater intrusion and coastal salinization, oxidation of organic carbon occurs. However, the main process operating during salinization or freshening events in coastal aquifers is cation exchange. The relative changes in Ca(2+), Sr(2+), and K(+) concentrations during salinization and freshening events are used as a reliable tool for characterizing the status of a coastal aquifer. The field data suggest that coastal aquifers may switch from freshening to salinization on a seasonal time scale.