Heavy Metal Contamination of Groundwater in Guwahati City, Assam, India

Heavy metal contamination of the groundwater in Guwahati city was assessed for their Cd, Pb, Fe and As contents. 27 groundwater samples were analysed using Atomic Absorption Spectrophotometer and the levels of the four heavy metals were compared to the WHO specified maximum contaminant levels. According to WHO, the Maximum Contaminant Level (MCL) for Cd is 0.003 mg/L, while for Pb and As are both 0.01 mg/L (or 10 mg/L), and for Fe permissible limit is 0.3 mg/L. From the results obtained, it was found that out of the 81.48% samples where Cd was present, all of them had Cd content above MCL. Out of the 100% samples where Pb was present, only 22.22%samples had Pb content just within MCL in the wet season, and only 7.4% within MCL in the dry season. Only one sample had Pb content below MCL in the dry season. 62.96% samples had Fe content above the WHO permissible limit in wet season, while 92.59% had it above the limit in dry season. Out of the 70.37% samples that had As content presentin wet season and 81.48% in dry season, all of the values were found to be below MCL in both seas