Rina, K., Datta, P. S., Singh, C. K., & Mukherjee, S. (2013). Isotopes and ion chemistry to identify salinization of coastal aquifers of Sabarmati River Basin. Current Science, 104(3), 335–344.
Abstract: The lower reaches of the Sabarmati River Basin in Gujarat have intense agricultural and industrial activities and this part is affected by problems of groundwater salinity. Here we attempt to assess the processes governing the causes of groundwater salinity in the coastal alluvial aquifer, employing δ18O and δD isotopes in integration with ionic ratio. The different hydrochemical facies such Na–Mg–HCO3–Cl, Na–Cl–SO4, Na–Mg–Cl–HCO3–SO4 and Na–Cl of groundwater show the occurrence of complex geochemical phenomenon in the study area. Ionic ratio (such as Mg2+/Ca2+, Na+/Cl−, SO24/Cl-, K+/Cl−) and isotopic composition (δ18O and δD) of groundwater indicate that while in coastal areas seawater intrusion is taking place, in inland areas various anthropogenic activities and overexploitation have induced salinity in groundwater. Over-pumping of groundwater has also induced lateral intermixing of highly saline water in the vicinity of coastal areas with relatively fresh/low saline groundwater along specific flow pathways.
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Di Lorenzo, T., & Galassi, D. M. P. (2013). Agricultural impact on Mediterranean alluvial aquifers: do groundwater communities respond? Fundamental and Applied Limnology/Archiv für Hydrobiologie, 182(4), 271–282.
Abstract: In Mediterranean countries agricultural development heavily depends on groundwater availability due
to arid and semi-arid climate and poor surface-water resources. Agriculture represents one of the most relevant
pressures which generate impacts in alluvial aquifers by means of fertilizers and pesticides usage and groundwater
overexploitation. Until now, very few studies have addressed the ecological response of groundwater fauna to
groundwater contamination and overexploitation due to agricultural practices. We investigated a Mediterranean
alluvial aquifer heavily affected by nitrates contamination and groundwater abstraction stress due to crop irrigation. The aim of this study was to evaluate the sensitivity of groundwater communities to (a) groundwater nitrate
contamination, (b) groundwater abstraction due to irrigation practices, and (c) saltwater intrusion. The present
work suggests that nitrate concentration lower than 150 mg l
–1 is not an immediate threat to groundwater biodiversity in alluvial aquifers. This conclusion must be carefully considered in the light of the total lack of knowledge
of the effects of long-term nitrate pollution on the groundwater biota. Moreover, local extinctions of less tolerant
species, prior to monitoring, cannot be ruled out. Conversely, species abundances in ground water are affected by
groundwater withdrawal, but species richness may be less sensitive. This result is attributable to the disappearance
of saturated microhabitats and to the depletion of fine unconsolidated sediments, reducing the surface available
to bacterial biofilm, which represent the trophic resource for several groundwater invertebrates and where the
main aquifer self-purification processes, such as denitrification, take place. Saltwater intrusion seems not to affect
groundwater species at the values measured in this coastal aquifer.
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Mongelli, G., Monni, S., Oggiano, G., Paternoster, M., & Sinisi, R. (2013). Tracing groundwater salinization processes in coastal aquifers: a hydrogeochemical and isotopic approach in the Na-Cl brackish waters of northwestern Sardinia, Italy. Hydrology and Earth System Sciences, 17(7), 2917–2928.
Abstract: Throughout the Mediterranean, salinization threatens water quality, especially in coastal areas. This salinization is the result of concomitant processes related to both seawater intrusion and water–rock interaction, which in some cases are virtually indistinguishable. In the Nurra region of northwestern Sardinia, recent salinization related to marine water intrusion has been caused by aquifer exploitation. However, the geology of this region records a long history from the Palaeozoic to the Quaternary, and is structurally complex and comprises a wide variety of lithologies, including Triassic evaporites. Determining the origin of the saline component of the Jurassic and Triassic aquifers in the Nurra region may provide a useful and more general model for salinization processes in the Mediterranean area, where the occurrence of evaporitic rocks in coastal aquifers is a common feature. In addition, due to intensive human activity and recent climatic change, the Nurra has become vulnerable to desertification and, in common with other Mediterranean islands, surface water resources periodically suffer from severe shortages. With this in mind, we report new data regarding brackish and surface waters (outcrop and lake samples) of the Na-Cl type from the Nurra region, including major ions and selected trace elements (B, Br, I, and Sr), in addition to isotopic data including δ18O, δD in water, and δ34S and δ18O in dissolved SO4. To identify the origin of the salinity more precisely, we also analysed the mineralogical and isotopic composition of Triassic evaporites. The brackish waters have Cl contents of up to 2025 mg L−1 , and the ratios between dissolved ions and Cl, with the exception of the Br / Cl ratio, are not those expected on the basis of simple mixing between rainwater and seawater. The δ18O and δD data indicate that most of the waters fall between the regional meteoric water line and the global meteoric water line, supporting the conclusion that they are meteoric in origin. A significant consequence of the meteoric origin of the Na-Cl-type water studied here is that the Br / Cl ratio, extensively used to assess the origin of salinity in fresh water, should be used with care in carbonate aquifers that are near the coast. Overall, δ34S and δ18O levels in dissolved SO4 suggest that water–rock interaction is responsible for the Na-Cl brackish composition of the water hosted by the Jurassic and Triassic aquifers of the Nurra, and this is consistent with the geology and lithological features of the study area. Evaporite dissolution may also explain the high Cl content, as halite was detected within the gypsum deposits. Finally, these Na-Cl brackish waters are undersaturated with respect to the more soluble salts, implying that in a climate evolving toward semi-arid conditions, the salinization process could intensify dramatically in the near future.
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Karatas, B. S., Camoglu, G., & Olgen, M. K. (2013). Spatio-temporal trend analysis of the depth and salinity of the groundwater, using geostatistics integrated with GIS, of the Menemen Irrigation System, Western Turkey. Ekoloji, 22(86), 36–47.
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