Assessment of metal pollution in surface water using pollution indices and multivariate statistics: a case study of Talcher coalfield area, India

Metal pollution in aquatic environment of coal mines is of serious concern and requires to be dealt with to maintain sustainable mining practices. The spatio-temporal variation in metal pollution of surface water of Talcher coalfield area were determined by using multivariate statistical techniques and pollution indices. A total of 56 water samples were collected and analyzed for Fe, Zn, Cu, Cd, Pb, Co, Se, As, Hg, Cr, Ni, Mn, and Al in pre-monsoon and monsoon season. Spatial distribution maps were prepared so that the quality of surface water could easily be recognized. High values of Heavy Metal Pollution Index (HPI), Degree of Contamination (Dc), and Heavy Metal Evaluation Index (HEI) were observed for 3%, 6%, 0% samples in pre-monsoon and 1%, 6%, 3% samples in monsoon. Sewage Treatment Plants (STP), Effluent Treatment Plants (ETP), and Mine Discharge Treatment Plants (MDTP) were found to have low to moderate efficiency in treating metals. The HPI of streams and rivers were observed to be higher in pre-monsoon than that of the monsoon season possibly due to dilution effect caused by intense rain in monsoon. The HPI of downstream was noted to be higher than the upstream indicating pollution due to mine effluent discharge. The average concentrations of Cd, Se, As, Ni, and Al in pre-monsoon and Fe, Cd, Se, As, Ni, and Al in monsoon exceeded the permissible drinking water limits set by WHO (WHO, Guidelines for drinking-water quality, World Health Organization, Geneva, 2011) and BIS (BIS (2012) Drinking water specifications 2nd revision. Bureau of Indian standards (IS 10500: 2012). New Delhi. ftp://law.resource.org/in/bis/S06/is.10500.2012.pdf). Analysis of Variance (ANOVA) revealed significant seasonal variation (p < 0.05) of Fe concentration between pre-monsoon and monsoon. Principal Component Analysis (PCA) identified major sources of metal pollution in water such as earth’s crust and the geological formation of the region, coal mining activities, industrial pollution, vehicular emission and coal burning. Cluster analysis (CA) identified 19 moderately polluted sites, 6 highly polluted sites, 3 very highly polluted sites and 1 severely polluted site in and around the Talcher coalfield area. This study is useful for formulating the metal pollution mitigation plan to enhance the water quality of Talcher coalfield area which affect the aquatic organism as well as the human health.