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Author Han, D.M.; Song, X.F.; Currell, M.J.; Yang, J.L.; Xiao, G.Q.
Title (up) Chemical and isotopic constraints on evolution of groundwater salinization in the coastal plain aquifer of Laizhou Bay, China Type Journal Article
Year 2014 Publication Journal of Hydrology Abbreviated Journal
Volume 508 Issue Pages 12-27
Keywords Laizhou Bay, Coastal aquifers, Groundwater hydrochemistry, Stable isotopes, Saltwater intrusion
Abstract Summary A hydrochemical-isotopic investigation of the Laizhou Bay Quaternary aquifer in north China provides new insights into the hydrodynamic and geochemical relationships between freshwater, seawater and brine at different depths in coastal sediments. Saltwater intrusion mainly occurs due to two cones of depression caused by concentrated exploitation of fresh groundwater in the south, and brine water for salt production in the north. Groundwater is characterized by hydrochemical zonation of water types (ranging from Ca–HCO3 to Na–Cl) from south to north, controlled by migration and mixing of saline water bodies with the regional groundwater. The strong adherence of the majority of ion/Cl ratios to mixing lines between freshwater and saline water end-members (brine or seawater) indicates the importance of mixing under natural and/or anthropogenic influences. Examination of the groundwater stable isotope δ18O and δ2H values (between −9.5‰ and −3.0‰ and −75‰ and −40‰, respectively) and chloride contents (∼2 to 1000meq/L) of the groundwater indicate that the saline end-member is brine rather than seawater, and most groundwater samples plot on mixing trajectories between fresh groundwater (δ18O of between −6.0‰ and −9.0‰; Cl<5meq/L) and sampled brines (δ18O of approximately −3.0‰ and Cl>1000meq/L). Locally elevated Na/Cl ratios likely result from ion exchange in areas of long-term freshening. The brines, with radiocarbon activities of ∼30 to 60 pMC likely formed during the Holocene as a result of the sequence of transgression-regression and evaporation; while deep, fresh groundwater with depleted stable isotopic values (δ18O=−9.7‰ and δ2H=−71‰) and low radiocarbon activity (<20 pMC) was probably recharged during a cooler period in the late Pleistocene, as is common throughout northern China. An increase in the salinity and tritium concentration in some shallow groundwater sampled in the 1990s and re-sampled here indicates that intensive brine extraction has locally resulted in rapid mixing of young, fresh groundwater and saline brine. The δ18O and δ2H values of brines (∼−3.0‰ and −35‰) are much lower than that of modern seawater, which could be explained by 1) mixing of original (δ18O enriched) brine that was more saline than presently observed, with fresh groundwater recharged by precipitation and/or 2) dilution of the palaeo-seawater with continental runoff prior to and/or during brine formation. The first mechanism is supported by relatively high Br/Cl molar ratios (1.7×10−3–2.5×10−3) in brine water compared with ∼1.5×10−3 in seawater, which could indicate that the brines originally reached halite saturation and were subsequently diluted with fresher groundwater over the long-term. Decreasing 14C activities with increasing sampling depth and increasing proximity to the coastline indicate that the south coastal aquifer in Laizhou Bay is dominated by regional lateral flow, on millennial timescales.
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ISSN 0022-1694 ISBN Medium
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Call Number THL @ christoph.kuells @ Han201412 Serial 174
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Author Mazor, E.
Title (up) Chemical and isotopic groundwater hydrology Type Book Whole
Year 2003 Publication Abbreviated Journal
Volume 98 Issue Pages
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Publisher CRC press Place of Publication Editor
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Call Number THL @ luqianxue.zhang @ mazor2003chemical Serial 102
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Author Elrashidi, M.A.; Adriano, D.C.; Workman, S.M.; Lindsay, W.L.
Title (up) Chemical equilibria of selenium in soils: a theoretical development1 Type Journal Article
Year 1987 Publication Soil Science Abbreviated Journal
Volume 144 Issue 2 Pages 141-152
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Publisher Lww Place of Publication Editor
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Call Number THL @ luqianxue.zhang @ elrashidi1987chemical Serial 103
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Author Deverel, S.J.; Fujii, R.
Title (up) Chemistry of trace elements in soils and ground water Type Journal Article
Year 1990 Publication Agricultural salinity assessment and management Abbreviated Journal
Volume Issue Pages 64-90
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Publisher American Society of Civil Engineers New York Place of Publication Editor
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Call Number THL @ luqianxue.zhang @ deverel1990chemistry Serial 69
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Author Petelet-Giraud, E.; Négrel, P.; Aunay, B.; Ladouche, B.; Bailly-Comte, V.; Guerrot, C.; Flehoc, C.; Pezard, P.; Lofi, J.; Dörfliger, N.
Title (up) Coastal groundwater salinization: Focus on the vertical variability in a multi-layered aquifer through a multi-isotope fingerprinting (Roussillon Basin, France) Type Journal Article
Year 2016 Publication Science of The Total Environment Abbreviated Journal
Volume 566-567 Issue Pages 398-415
Keywords Groundwater salinization, Coastal aquifer, Roussillon Basin, Isotopes, Westbay System, Barcarès and Canet sites
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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ISSN 0048-9697 ISBN Medium
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Call Number THL @ christoph.kuells @ Peteletgiraud2016398 Serial 181
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