Heavy Metal Pollution Assessment Of Groundwater In The Itanagar Capital Region Using Hpi

Abstract

Groundwater has always been a major source of drinking water in Itanagar Capital Region (ICR), Arunachal Pradesh. However, the quality of groundwater is getting compromised mainly due to fast urbanisation and man made activities. Groundwater pollution in terms of heavy metals is quantitatively evaluated in this study using the Heavy Metal Pollution Index (HPI). Water gathered from wells, borewells, and springs scattered in Itanagar, Naharlagun, and Nirjuli during the pre monsoon and post-monsoon seasons were tested for resulting concentrations of Fe, Pb, Cr, Cu, Cd, Zn, Hg, and As. Comparison of these values was done with the standards laid down by both Bureau of Indian Standards and World Health Organisation. The assessment results show that the levels of most of the metals are still considered safe. Higher concentrations of Fe, Pb, and Cr have been found only at a few locations. At some locations, pre monsoon iron concentration was as high as 2.05 mg/L than the permissible limit of 0.3 mg/L. Other two heavy metals Chromium and Lead at Sites 10 and 17 also went beyond the safe limits. Heavy Metal Pollution Index (HPI) results unveiled that most sites have low to moderate level of heavy metal pollution except the Sites 10, 17, and 20 which showed high pollution levels. It is generally observed that metal concentrations in post-monsoon water tend to be lower than that of pre-monsoon waters. This is a natural consequence of dilution and groundwater recharge. This report points out that, in general, the water quality in ICR is good. At the same time, it highlights that localized regions getting contaminated with a great deal of the elements require not only constant vigilance but also application of specific water treatment techniques.