Seasonal variations of groundwater arsenic at Silchar, Assam, and its correlation with the flood plains and landfill area.

In this study, we collected 60 samples from 30 sites in pre- and post-monsoon from Silchar municipal area (15.75 sq. km of Cachar district, Assam) during 2012– 13 to evaluate seasonal variations in groundwater arsenic. It was observed that 27% were safe (0–10 μg/l), while 18% exceeded alarming zone (51– 100 μg/l) and 3% were in the most alarming zone (>100 μg/l). The highest arsenic contamination of 188 and 161 μg/l was recorded in pre- and post-monsoon. The pH and EC ranged from 5.6–7.4 and 132– 854 μS/cm in pre-monsoon. The iron content varied from 0.1 and 9.7 mg/l. Flood plains and landfill areas constituted the majority of arsenic-affected aquifers. [ABSTRACT FROM AUTHOR]