Three Special Study Areas in Bangladesh were chosen for detailed hydrogeological, hydrochemical and sedimentological studies.
The areas chosen were the headquarter upazilas (local administrative divisions) of the Districts of Lakshmipur, Faridpur and Nawabganj.
Samples were also collected from Shibganj upazila, the neighbouring upazila to Chapai Nawabganj headquarter upazila (Nawabganj District) and Chatkil upazila (neighbouring upazila to Lakshmipur headquarter upazila).
The three study areas were selected on the basis of recognised arsenic problems, their wide geographical distribution across the alluvial and deltaic plains of Bangladesh and their range of differing geological and hydrogeological characteristics.
Analysis of major and minor ions in the samples was by ICP-AES and ICP-MS; arsenic was measured by ICP-AES with hydride generation or AFS with hydride generation. Anions were analysed by automated colorimetry or ion chromatography. All analyses were carried out in BGS laboratories.
The hydrogeochemical data are presented for the Special Study Areas as point-source maps (links below). An inset is included for Chapai Nawabganj to highlight the spatial chemical variation and greater density of sampling within the municipal area.
The maps also give the surface geology of each study area (taken from the Bangladesh geological map, Alam et al., 1990), the legend of which is given in the geology base map. In each map, shallow wells (<150 m deep) are given as filled circles, deep wells (>150 m deep) as triangles. A map showing sample numbers is also available.
The maps are in Adobe Acrobat PDF format, each file is less than 500 KB.
Contact Dr Pauline Smedley for further information