A STUDY OF VARIABLES AFFECTING TOXIC ELEMENTS IN WELL WATER FROM FOUR WESTERN BANGLADESH VILLAGES, WITH IMPLICATIONS ON DRINKING WATER USE AND POLICY

Groundwater (drinking water) samples were collected from 4 neighborhoods in western Bangladesh (Bualda, Fulbaria, Jamjami, and Komlapur). To the extent possible, the sampled tubewells in each neighborhood were distributed at 500-meter intervals along perpendicular axes that radiated in 4 equal lengths from the center. Each neighborhood had 17 sampling locations: 4 north, 4 east, 4 south, 4 west, and 1 in the center. Each sample was analyzed for arsenic (As), uranium (U), manganese (Mn), nickel (Ni), antimony (Sb), lead (Pb), chromium (Cr), iron (Fe), pH, boron (B), barium (Ba), molybdenum (Mo), selenium (Se), and zinc (Zn). In this study, As, U, Mn, Ni, Sb, Pb, and Cr, were found above WHO health-based drinking water guidelines in 33%, 48%, 75%, 3%, 3%, 1%, and 1% of these tubewells, respectively. Conversely, B, Ba, and Mo were not found above these guidelines. The maximum concentrations of As, U, Mn, Ni, Sb, Pb, Cr, Fe, B, Ba, Mo, Se, and Zn were 590 μg/L, 10 μg/L, 2,400 μg/L, 570 μg/L, 6.2 μg/L, 17 μg/L, 100 μg/L, 66,000 μg/L, 440 μg/L, 690 μg/L, 7.8 μg/L, 1 μg/L, and 88 μg/L, respectively. Statistical methods and interviews were used to determine the effects of depth of tubewell, age of tubewell, and number of users per tubewell on pH and on concentrations of 13 toxic elements in the groundwater. In addition, potential effects of local geology and hydrology on groundwater chemistry were examined through satellite images, existing regional geologic data, and element concentration contour maps. In addition, the long-term implications of these toxic elements on public health and drinking water supply in western Bangladesh are evaluated.