Groundwater Heavy Metal Contamination Mapping Using Geographic Information System (GIS): A Case of Nashik Thermal Power Station, Eklahare, Nashik (M.S.), India

Abstract

AbstractCoal-based thermal power plants generate a significant amount of fly ash and are facing fly ash management problems, which is emerging as a major environmental concern. Commonly, fly ash is disposed of in an unlined earthen pond, which may lead to contamination of groundwater in surrounding areas due to the leaching of heavy metals through fly ash. In the present study, hydro-geochemical analysis is carried out on groundwater samples from the proximity of Nashik Thermal Power Station, Eklahare village, to assess the impact. The heavy metals, i.e. Cd, Hg, and Pb, are selected and analysed in groundwater samples during pre-monsoon and post-monsoon seasons due to its high concentration in coal and fly ash samples. The analysis results showed that the maximum concentration of Cd is 0.0068 mg/l and 0.017 mg/l; Hg is 0.36 mg/l and 0.032 mg/l; and Pb is 0.23 mg/l and 0.075 mg/l during the pre-monsoon and post-monsoon seasons, respectively. Around 33.33%, 58.33%, and 41.67% of samples in pre-monsoon have concentration beyond desirable limit of the Bureau of Indian Standard, 2012 for Cd, Hg, and Pb, respectively. While 58.66%, 66.67%, and 50% of samples in the post-monsoon season have exceeded desirable limits. Spatial distribution maps for selected heavy metals are prepared using the IDW data interpolation technique in GIS. The maps showed that the ash pond is adversely affecting the groundwater quality in the village, thereby creating a threat to the health of residents and indicate the need for corrective measures to check the infiltration of leachate from the ash pond. Based on contamination zones, the location of a new groundwater source can be planned.KeywordsThermal power stationGroundwaterHeavy metal contaminationIntegrated distance weighingGeographic information system