Hydrogeochemical contrasts across the multi-level aquifers of Bengal basin in Matlab, Bangladesh : Implications for arsenic free and low-manganese drinking water sources

• Targeting shallow, intermediate-deep and deep aquifers, piezometers nests were installed at 15 locations in the Matlab region, an As hotspot in southeastern Bangladesh. Groundwater levels and water quality were monitored for over a three years period. Stable isotopic composition was used to identify the hydrogeological characteristics of different aquifers, hydraulic connectivity between the contaminated and safe aquifers. Within the shallow depth (up to 100m), two aquifers (Aquifer-1 and Aquifer-2) were identified, and groundwater from Aquifer-1 indicated consistently high As concentration was found to be As-enriched (median As levels upto 714 μg/L). Considerable variability in As concentrations were observed in Aquifer-2 wells (6–30 μg/L) comprising relatively oxidized or less reduced red and off-white sands. The intermediate-deep and deep aquifers were found to contain very low As concentration and these aquifers are hydraulically separated from the shallow aquifers. Groundwater depth and elevation and stable isotope signatures also reflect that intermediate-deep and deep aquifers, in most places belong to the same hydrostratigraphic unit (Aquifer-3).

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Nyckelord

Aquifers

Arsenic

Groundwater

Groundwater pollution

Hydrogeology

Isotopes

Potable water

Sustainable development

Water quality

Drinking water sources

Ground water depths

Hydraulic connectivity

Hydrogeochemical

Hydrogeological characteristics

Shallow aquifers

Stable isotopes

Stable isotopic compositions

Groundwater resources

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