Abstract
Groundwater arsenic contamination is now one of the most significant problems in Bangladesh. Role of depth, seasons, locations and age of tube well for groundwater arsenic variation in Bangladesh was studied. MERCK arsenic test kit was used to determine arsenic concentration variation. Tube well water depth was measured with the help of an avometer, measuring tap and plastic insulated wire. Also, depth and age of the tube wells were determined through asking questions, secondary sources of DPHE and Union Council. Results indicate that arsenic concentration levels are about 41.31% under WHO guideline (0.01 mg/l), 29.69% are within the permissible level (0.05 mg/l) and 29% exceed the permissible level (> 0.05 mg/l). No relation was observed between arsenic concentration and water table depth. At depth below 15 m, 92.68% of tube wells were arsenic level under WHO guideline (0.01 mg/l), 4.88% within permissible limit (0.05 mg/l) and 2.44% exceeding permissible limit (>0.05 mg/l). At depth between 15 and 30 m, 40.43% of tube wells were arsenic levels under WHO guideline, 34.04% within the permissible limit and 25.53% exceeding the permissible limit. At depths between 31 and 46 m, 25.49% of tube wells were arsenic levels under WHO guideline, 39.22% within the permissible limit and 35.29% exceeding the permissible limit. At depth between 46 and 76 m, no tube well was arsenic level under WHO guideline, 40% within permissible limit and 60% exceeding permissible limit. But, there were many significant changes observed in each depth from below 30 m to above 70 m. Less arsenic concentration was observed in the dry season as compared to the wet season. Less significant difference was observed within locations. Result showed that from less than 15 m to 76 m depth arsenic concentration trend is higher in each tube well that was installed since eighties.
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