Arsenic in the Bengal Delta Plain: geochemical complications and potential mitigation option

Arsenic in the Bengal Delta Plain: geochemical complications and potential mitigation option

Groundwaters from the Bengal Delta Plain (BDP) are now significantly enriched with natural arsenic (As), frequently exceeding the WHO guideline value (10 μg/L). The contaminated ground-water is often derived from geologically young sediments (Holocene), low-lying areas and flat terrain where groundwater movement is slow (poorly flushed aquifers). The As content of the aquifer material is not regularly high (3–18 mg/kg), however, the groundwater As content is often exceptionally high (up to 3200 μg/L). The most notable feature of the tubewell groundwater is their predominantly reducing conditions at near-neutral pH values (6.5–7.5) with high redox sensitive species. The issue of deeper aquifer (safe and unsafe) is most challenging in terms of both geological and public health point of view. In this context, deeper aquifer is possibly the most reliable source where remediation technologies are in many cases incapable of yielding As-safe water.

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