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Hydrogeochemical an...
Hydrogeochemical and isotopic signatures for the identification of seawater intrusion in the paleobeach aquifer of Cox's Bazar city and its surrounding area, south-east Bangladesh
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Seddique, A. A. (author)
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Masuda, H. (author)
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Anma, R. (author)
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- Bhattacharya, Prosun, 1962- (author)
- KTH,Hållbar utveckling, miljövetenskap och teknik
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Yokoo, Y. (author)
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Shimizu, Y. (author)
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(creator_code:org_t)
- Elsevier B.V. 2019
- 2019
- English.
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In: Groundwater for Sustainable Development. - : Elsevier B.V.. - 2352-801X. ; 9
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- In order to better understand the encroachment of seawater into the groundwater system a total 115 groundwater samples were collected in an area of ∼7 km 2 in Cox's Bazar paleobeach and its vicinity, from different types of tubewells, which included hand pump fitted bore wells (<50 m depth), moderately deep energized bore wells (50 m–100 m depth) and deep bore wells (>100 m depth) during June 2013. A combined hydro-geochemical indicators, selected trace elements (Sr and B) and in addition to δ 18 O and δ 2 H were used in this study. Results show that the high values of EC (202 μS/cm to 6730 μS/cm) and TDS (135 mg/L to 4509 mg/L) are found in groundwater of wells closer to the coast and few wells from the northern and central part of the study area. The cross plot of HCO 3 /Cl and TDS shows that groundwater along the paleobeach and some isolated areas are saline with TDS > 1000 mg/L, associated with high ratios of Cl/TDS (0.065). The groundwater facies generally evolves from freshwater (Ca-Mg-HCO 3 ) to saline water (Na- Cl) type with an intermediate Ca-Mg-Cl type indicating that the aquifer system interacts with seawater and undergoes cation exchange. Results also reveal that the area affected by marine water intrusion has ionic ratios of Br/Cl (0.0006–0.0021) similar to seawater (0.0015) with some higher values. Groundwaters along the paleobeach and some isolated areas, low ionic ratios of SO 4 /Cl (0.01–6.53) and Na/Cl (0.20–152.09), relative to marine ratios (0.05 and 0.86 respectively), are also observed. Groundwaters with Seawater Mixing Index >1.0 and TDS >1000 mg/L constitute about 20% of the studied groundwaters and have relatively high δ 18 O (>- 4.0‰) values and the linear relationships between TDS and most of the ions, including B and Sr, and the chemical signature of the saline plumes (e.g., marine SO 4 /Cl, Na/Cl and Br/Cl ratios) suggest that mixing processes control the chemical composition of the seawater within the aquifers. However, these geochemical variations also reveal that the quality of potable water has deteriorated to a large extent due to seawater intrusion along the paleobeach, migrating inland toward the heavily groundwater exploited areas from the coast line and may entail various future health hazards.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)
Keyword
- Coastal groundwater
- Cox's Bazar
- Paleobeach
- Seawater intrusion
Publication and Content Type
- ref (subject category)
- art (subject category)
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