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Kurunc, A., Ersahin, S., Sonmez, N. K., Kaman, H., Uz, I., Uz, B. Y., et al. (2016). Seasonal changes of spatial variation of some groundwater quality variables in a large irrigated coastal Mediterranean region of Turkey. Science of the Total Environment, 554, 53–63.
Abstract: Soil and groundwater degradations have taken considerable attention, recently. We studied spatial and temporal variations of groundwater table depth and contours, and groundwater pH, electrical conductivity (EC), and nitrate (NO3) content in a large irrigated area in Western Mediterranean region of Turkey. These variables were
monitored during 2009 and 2010 in previously constructed 220 monitoring wells. We analyzed the data by geostatistical techniques and GIS. Spatial variation of groundwater table depth (GTD) and groundwater table contours (GTC) remained similar across the four sampling campaigns. The values for groundwater NO3 content, EC, and pH values ranged from 0.01 to 454.1 g L−1 , 0.06 to 46.0 dS m−1 and 6.53–9.91, respectively. Greatest
geostatistical range (16,964 m) occurred for GTC and minimum (960 m) for groundwater EC. Groundwater NO3 concentrations varied both spatially and temporally. Temporal changes in spatial pattern of NO3 indicated that land use and farming practices influenced spatial and temporal variation of groundwater NO3. Several hot spots occurred for groundwater NO3 content and EC. These localities should be monitored more frequently and
land management practices should be adjusted to avoid soil and groundwater degradation. The results may have important implications for areas with similar soil, land use, and climate conditions across the Mediterranean region.
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Mihajlidi-Zelić, A., Deršek-Timotić, I., Relić, D., Popović, A., & Đorđević, D. (2006). Contribution of marine and continental aerosols to the content of major ions in the precipitation of the central Mediterranean. Science of the total environment, 370(2-3), 441–451.
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Cary, L., Petelet-Giraud, E., Bertrand, G., Kloppmann, W., Aquilina, L., Martins, V., et al. (2015). Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): a multi-isotope approach. Science of the Total Environment, 530-531, 411–429.
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Petelet-Giraud, E., Négrel, P., Aunay, B., Ladouche, B., Bailly-Comte, V., Guerrot, C., et al. (2016). Coastal groundwater salinization: Focus on the vertical variability in a multi-layered aquifer through a multi-isotope fingerprinting (Roussillon Basin, France). Science of The Total Environment, 566-567, 398–415.
Abstract: The Roussillon sedimentary Basin (South France) is a complex multi-layered aquifer, close to the Mediterranean Sea facing seasonally increases of water abstraction and salinization issues. We report geochemical and isotopic vertical variability in this aquifer using groundwater sampled with a Westbay System® at two coastal monitoring sites: Barcarès and Canet. The Westbay sampling allows pointing out and explaining the variation of water quality along vertical profiles, both in productive layers and in the less permeable ones where most of the chemical processes are susceptible to take place. The aquifer layers are not equally impacted by salinization, with electrical conductivity ranging from 460 to 43,000μS·cm−1. The δ2H–δ18O signatures show mixing between seawater and freshwater components with long water residence time as evidenced by the lack of contribution from modern water using 3H, 14C and CFCs/SF6. S(SO4) isotopes also evidence seawater contribution but some signatures can be related to oxidation of pyrite and/or organically bounded S. In the upper layers 87Sr/86Sr ratios are close to that of seawater and then increase with depth, reflecting water–rock interaction with argillaceous formations while punctual low values reflect interaction with carbonate. Boron isotopes highlight secondary processes such as adsorption/desorption onto clays in addition to mixings. At the Barcarès site (120m deep), the high salinity in some layers appear to be related neither to present day seawater intrusion, nor to Salses-Leucate lagoonwater intrusion. Groundwater chemical composition thus highlights binary mixing between fresh groundwater and inherited salty water together with cation exchange processes, water–rock interactions and, locally, sedimentary organic matter mineralisation probably enhanced by pyrite oxidation. Finally, combining the results of this study and those of Caballero and Ladouche (2015), we discuss the possible future evolution of this aquifer system under global change, as well as the potential management strategies needed to preserve quantitatively and qualitatively this water resource.
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Faye, S., Maloszewski, P., Stichler, W., Trimborn, P., Faye, S. C., & Gaye, C. (2005). Groundwater salinization in the Saloum (Senegal) delta aquifer: minor elements and isotopic indicators. Science of The Total Environment, 343(1), 243–259.
Abstract: The hydrochemistry of minor elements bromide (Br), boron (B), strontium (Sr), environmental stable isotopes (18O and 2H) together with major-ion chemistry (chloride, sodium, calcium) has been used to constrain the source(s), relative age, and processes of salinization in the Continental Terminal (CT) aquifer in the Saloum (mid-west Senegal) region. Seventy-one groundwater wells which include 24 wells contaminated by saltwater and three sites along the hypersaline Saloum River were sampled to obtain additional information on the hydrochemical characteristics of the groundwater defined in previous studies. Use of Br against Cl confirms the Saloum River saline water intrusion up to a contribution of 7% into the aquifer. In addition to this recent intrusion, a relatively ancient intrusion of the Saloum River water which had reached at least as far as 20 km south from the source was evidenced. The high molar ratio values of Sr/Cl and Sr/Ca indicate an additional input of strontium presumably derived from carbonate precipitation/dissolution reactions and also via adsorption reactions. The variable B concentrations (7–650 μg/L) found in the groundwater samples were tested against the binary mixing model to evaluate the processes of salinization which are responsible for the investigated system. Sorption of B and depletion of Na occur as the Saloum river water intrudes the aquifer (salinization) in the northern part of the region, whereas B desorption and Na enrichment occur as the fresh groundwater flushing displaces the saline waters in the coastal strip (refreshening). In the central zone where ancient intrusion prevailed, the process of freshening of the saline groundwater is indicated by the changes in major-ion chemistry as well as B desorption and Na enrichment. In addition to these processes, stable isotopes reveal that mixing with recently infiltrating waters and evaporation contribute to the changes in isotopic signature.
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