Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam
Study region: Ca Mau Province (CMP), Mekong Delta (MD), Vietnam. Study focus: Groundwater from deep aquifers is the most reliable source of freshwater in the MD but extensive overexploitation in the last decades led to the drop of hydraulic heads and negative environmental impacts. Therefore, a comp...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-04-01
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| Series: | Journal of Hydrology: Regional Studies |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214581822000234 |
| _version_ | 1818338707109838848 |
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| author | Jonas Bauer Nicolas Börsig Van Cam Pham Tran Viet Hoan Ha Thi Nguyen Stefan Norra |
| author_facet | Jonas Bauer Nicolas Börsig Van Cam Pham Tran Viet Hoan Ha Thi Nguyen Stefan Norra |
| author_sort | Jonas Bauer |
| collection | DOAJ |
| description | Study region: Ca Mau Province (CMP), Mekong Delta (MD), Vietnam. Study focus: Groundwater from deep aquifers is the most reliable source of freshwater in the MD but extensive overexploitation in the last decades led to the drop of hydraulic heads and negative environmental impacts. Therefore, a comprehensive groundwater investigation was conducted to evaluate its composition in the context of Quaternary marine transgression and regression cycles, geochemical processes as well as groundwater extraction. New hydrological insights for the region: The abundance of groundwater of Na-HCO3 type and distinct ion ratios, such as Na+/Cl-, indicate extensive freshwater intrusion in an initially saline hydrogeological system, with decreasing intensity from upper Pleistocene to deeper Miocene aquifers, most likely during the last marine regression phase 60–12 ka BP. Deviations from the conservative mixing line between the two endmembers seawater and freshwater are attributed to ion-exchange processes on mineral surfaces, making ion ratios in combination with a customized water type analysis a useful tool to distinguish between salinization and freshening processes. Elevated salinity in some areas is attributed to HCO3- generation by organic matter decomposition in marine sediments rather than to seawater intrusion. Nevertheless, a few randomly distributed locations show strong evidence of recent salinization in an early stage, which may be caused by the downwards migration of saline Holocene groundwater through natural and anthropogenic pathways into deep aquifers. |
| first_indexed | 2024-12-13T15:15:23Z |
| format | Article |
| id | doaj.art-63c7a35c091949959c50064bee252f17 |
| institution | Directory Open Access Journal |
| issn | 2214-5818 |
| language | English |
| last_indexed | 2024-12-13T15:15:23Z |
| publishDate | 2022-04-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Hydrology: Regional Studies |
| spelling | doaj.art-63c7a35c091949959c50064bee252f172022-12-21T23:40:43ZengElsevierJournal of Hydrology: Regional Studies2214-58182022-04-0140101010Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, VietnamJonas Bauer0Nicolas Börsig1Van Cam Pham2Tran Viet Hoan3Ha Thi Nguyen4Stefan Norra5Karlsruhe Institute of Technology (KIT), Institute of Applied Geosciences, Adenauerring 20b, 76131 Karlsruhe, Germany; Corresponding author.Karlsruhe Institute of Technology (KIT), Institute of Applied Geosciences, Adenauerring 20b, 76131 Karlsruhe, GermanyKarlsruhe Institute of Technology (KIT), Institute of Applied Geosciences, Adenauerring 20b, 76131 Karlsruhe, GermanyKarlsruhe Institute of Technology (KIT), Institute of Applied Geosciences, Adenauerring 20b, 76131 Karlsruhe, Germany; National Center for Water Resources Planning and Investigation (NAWAPI), No. 93, lane 95, Vu Xuan Thieu Street Sai Dong Ward, Long Bien District, Hanoi, Viet NamNational Center for Water Resources Planning and Investigation (NAWAPI), No. 93, lane 95, Vu Xuan Thieu Street Sai Dong Ward, Long Bien District, Hanoi, Viet NamPotsdam University, Institute of Environmental Sciences and Geography, Soil Sciences and Geoecology, Campus Golm, Building 12, 14476 Potsdam - Golm, GermanyStudy region: Ca Mau Province (CMP), Mekong Delta (MD), Vietnam. Study focus: Groundwater from deep aquifers is the most reliable source of freshwater in the MD but extensive overexploitation in the last decades led to the drop of hydraulic heads and negative environmental impacts. Therefore, a comprehensive groundwater investigation was conducted to evaluate its composition in the context of Quaternary marine transgression and regression cycles, geochemical processes as well as groundwater extraction. New hydrological insights for the region: The abundance of groundwater of Na-HCO3 type and distinct ion ratios, such as Na+/Cl-, indicate extensive freshwater intrusion in an initially saline hydrogeological system, with decreasing intensity from upper Pleistocene to deeper Miocene aquifers, most likely during the last marine regression phase 60–12 ka BP. Deviations from the conservative mixing line between the two endmembers seawater and freshwater are attributed to ion-exchange processes on mineral surfaces, making ion ratios in combination with a customized water type analysis a useful tool to distinguish between salinization and freshening processes. Elevated salinity in some areas is attributed to HCO3- generation by organic matter decomposition in marine sediments rather than to seawater intrusion. Nevertheless, a few randomly distributed locations show strong evidence of recent salinization in an early stage, which may be caused by the downwards migration of saline Holocene groundwater through natural and anthropogenic pathways into deep aquifers.http://www.sciencedirect.com/science/article/pii/S2214581822000234Ca MauHydrogeologyDelta aquifer systemSalinityFreshwaterSeawater intrusion |
| spellingShingle | Jonas Bauer Nicolas Börsig Van Cam Pham Tran Viet Hoan Ha Thi Nguyen Stefan Norra Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam Journal of Hydrology: Regional Studies Ca Mau Hydrogeology Delta aquifer system Salinity Freshwater Seawater intrusion |
| title | Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam |
| title_full | Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam |
| title_fullStr | Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam |
| title_full_unstemmed | Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam |
| title_short | Geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost Mekong Delta, Vietnam |
| title_sort | geochemistry and evolution of groundwater resources in the context of salinization and freshening in the southernmost mekong delta vietnam |
| topic | Ca Mau Hydrogeology Delta aquifer system Salinity Freshwater Seawater intrusion |
| url | http://www.sciencedirect.com/science/article/pii/S2214581822000234 |
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