Monsoonal influence on variation of hydrochemistry and isotopic signatures: Implications for associated arsenic release in groundwater
| Autor: | Debashis Chatterjee, Simita Sarkar, D. Chatterjee, Gabriela Roman-Ross, Santanu Majumder, Zsolt Berner, Saugata Datta, Bibhash Nath, Harald Neidhardt, Manuela Hidalgo |
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| Rok vydání: | 2016 |
| Předmět: |
Hydrology
geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Global meteoric water line Floodplain δ18O Aquifer Groundwater recharge 010501 environmental sciences 01 natural sciences Hydrology (agriculture) Surface water Groundwater Geology 0105 earth and related environmental sciences Water Science and Technology |
| Zdroj: | Journal of Hydrology. 535:407-417 |
| ISSN: | 0022-1694 |
| Popis: | Summary The present study examines the groundwater and surface water geochemistry of two different geomorphic domains within the Chakdaha block, West Bengal, in an attempt to decipher potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer, the effect of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and concomitant As release. A low-land flood plain and a natural levee have been selected for this purpose. Although the stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) are largely controlled by local precipitation, the isotopic composition falls sub-parallel to the Global Meteoric Water Line (GMWL). The Cl/Br molar ratio indicates vertical recharge into the wells within the flood plain area, especially during the post-monsoon season, while influences of both evaporation and vertical mixing are visible within the natural levee wells. Increase in mean DOC concentrations (from 1.33 to 6.29 mg/L), from pre- to post-monsoon season, indicates possible inflow of organic carbon to the aquifer during the monsoonal recharge. Concomitant increase in AsT, Fe(II) and HCO3− highlights a possible initial episode of reductive dissolution of As-rich Fe-oxyhydroxides. The subsequent sharp increase in the mean As(III) proportions (by 223%), particularly in the flood plain samples during the post-monsoon season, which is accompanied by a slight increase in mean AsT (7%) may refer to anaerobic microbial degradation of DOC coupled with the reduction of As(V) to As(III) without triggering additional As release from the aquifer sediments. |
| Databáze: | OpenAIRE |
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