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.
Keywords: Arsenic, depth, seasons, age of tube wells, Bangladesh
