Metal Contamination in Ground Water of Dang District

Abstract

Drinking water quality in Nepal has been an issue of prevalent concern. So, this study was conducted to visualize the scenario of metal contamination in ground water of Dang district located at central west Terai in Nepal. A total of 523 water samples from tubewells and dugwells positioned in 16 village development committees (VDCs) were tested for arsenic in laboratory using atomic absorption spectrophotometer (AAS) employing continuous flow hydride generation technique. Randomly selected 20 samples were also tested for other heavy and trace metals like Mn, Fe, Cu, and Cd using AAS employing flame method. Of the total samples, 50.3% was found to contain arsenic above WHO drinking water qualty guidelines value of 10 ppb (0.01 mg/l) and 10.7% was found to contain arsenic above national drinking water quality guidelines value of 50 ppb (0.05 mg/l). The safest VDC is Sonpur while the most severely affected VDC is Gobardiha. A highest concentration of As of 240 ppb (0.24 mg/ l) was found in Dhikpur VDC. Ground water in this area seemed to be affected by high concentration of iron up to 11.01 mg/l and of manganese up to 0.51 mg/L. Statistical tools were employed to assess the probable association among metals but no significant correlation could be retrieved. Key words: hydride generation-atomic absorption spectrophotometry; redox conversion; arsenicosis; heavy and trace metals DOI: 10.3126/njst.v9i0.3178 Nepal Journal of Science and Technology 9 (2008) 143-148