Keywords: agriculture, drinking water, groundwater, pesticides, water-quality standards
Effect of agro-activities on drinking-water quality in Bangladesh
Fifty-nine samples of drinking water were collected from various locations in Bangladesh to assess the impact of agricultural practices on groundwater quality. The basic groundwater quality parameters, such as pH, total dissolved solids, iron, sodium, chloride, sulfate, fluoride and arsenic were analysed. In addition, the presence of excess fertilizers was monitored by measuring levels of ammonium, nitrate, phosphate and potassium, and the presence of excess pesticides by measuring levels of endrin, heptachlor and DDT. The results were evaluated on the basis of drinking-water quality standards for Bangladesh as well as WHO and EC standards. Water samples were found to contain relatively high concentrations of ammonium, nitrate and iron. The ranges of the organochlorine pesticides heptachlor and DDT were 0.025-0.789 mg/l and 0.010-1.527 mg/l, respectively. Two samples violated the allowable limits for heptachlor, seven for DDT. The presence of low levels of persistent pesticides at certain locations, along with higher than normal levels of ammonium and nitrate clearly demonstrates that agro-chemicals have influenced the water quality of groundwater sources in Bangladesh.