Arsenic Contamination in Groundwater, Soil and Rice Grain of Nepal

Arsenic (As) contamination in groundwater is a serious issue of many countries which can contaminate soil & crops growing in that area. The As contamination in water, soil & crops was evaluated from As affected district Nawalparasi (Nepal). The As level in water was above the national (0.05 mgL-1) & WHO standards (0.01 mg L-1). However, soil & rice grain samples showed As contamination in safe level. Water samples showed As concentration in the range of 0.1 mg L-1 to 1.86 mg L-1 except one sample (0.009 mg L-1). The average As concentration in pre/post monsoon season were 0.73 mg L-1 & 0.59 mg L-1. 66.67% water samples showed higher As concentration in pre-monsoon season. As concentration in all soil samples were in the range of 0.35 mg kg-1 to 9.55 mg kg-1 with average of 3.14 mg kg-1 which is below 20 mg of As kg−1 in soil as the safe level in agricultural soil for crops. In rice grain samples, the average As concentration was about 0.738 mg kg-1 which is below 1.0 mg kg−1 as food hygiene standard level of As. Specifically, four rice grain samples contained As level in the range of 0.35 mg kg-1 to 1.9 mg kg-1 & three samples showed below detection limit (0.005 mg kg-1).