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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Joseph, J., Külls, C., Arend, M., Schaub, M., Hagedorn, F., Gessler, A., et al. (2019). Application of a laser-based spectrometer for continuous in situ measurements of stable isotopes of soil CO 2 in calcareous and acidic soils. Soil, 5(1), 49–62.
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Elrashidi, M. A., Adriano, D. C., Workman, S. M., & Lindsay, W. L. (1987). Chemical equilibria of selenium in soils: a theoretical development1. Soil Science, 144(2), 141–152.
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Kisi, O., Heddam, S., Parmar, K. S., Yaseen, Z. M., & Kulls, C. (2024). Improved monthly streamflow prediction using integrated multivariate adaptive regression spline with K-means clustering: implementation of reanalyzed remote sensing data. Stochastic Environmental Research and Risk Assessment, 38(6), 2489–2519.
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Araguás-Araguás, L. (2003). Identification of the mechanisms and origin of salinization of groundwater in coastal aquifers by isotope techniques. Tecnología de la intrusión de agua de mar en acuíferos costeros, Países Mediterráneos, , 365–371.
Abstract: When assessing the origin of salinity and the mechanisms of salinization in coastal aquifers, hydrogeologists may consider the combined use of certain geochemical tools to assess critical aspects of the hydrogeological setting of the system. These tools are based in the integrated use of chemical (major ions, trace elements and ionic ratios) and isotope parameters (oxygen, hydrogen, sulphur, carbon, strontium and boron). The problem of groundwater salinization in coastal aquifers, besides active seawater intrusion, may be affected by several human activities that accelerate the progressive deterioration of water quality, such as concentrated pumping, intensive agricultural practices including return flows or reuse of waste waters from urban or industrial origin. The characterisation of the perating processes and mechanisms of salinization is a requisite for a proper management of groundwater resources and for adopting remediation strategies. In this contribution the potential role of several isotopic tools in these studies is briefly described.
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