Assessment of Soil Contamination in and Around Municipal Solid Waste Landfills of Ghazipur and Narela-Bawana, Delhi

Abstract

Abstract This research was designed to evaluate soil contamination in the Ghazipur (non-engineered) and Narela-Bawana (engineered) landfills of Delhi. The soil sampling was carried out at five locations in each landfill that includes landfill sites and their surrounding areas. Total ten physicochemical parameters and eight heavy metals were investigated. Heavy metal contamination in soil samples was evaluated using geochemical indices (CF, PLI, EF, PN and Igeo). The results showed high pH (>7.5)and chloride levels (> 150 mg/kg) exceeding their safe limits at all sampling sites ofboth landfills, indicating significant leachate and soil contamination. Phosphate and sulphate levels were found below their minimal range in both landfill areas, indicating deficiency of these essential soil nutrients. Zn, Cu and Cd were found above their maximum permissible limit at one or more sampling sites of both landfill areas, along with Pb at site 2 of Narela-Bawana landfill. Correlation analysis indicated general co-variation patterns among physicochemical parameters and heavy metals. The overall metal contamination for both seasons was found to be dominated by Zn, Cu and Pb at Ghazipur landfill sites(CF=3.28–13.53), where as Zn, Cu, Pb and Mn at Narela-Bawana landfill sites (CF=3.11–53.91). The PLI values (>1) indicated considerable heavy metal pollution at landfill site and site 4 of Ghazipur landfill and at all sampling sites of Narela-Bawana landfill except site 3. The EF values (>5.5) of Zn, Cu and Pbindicated their anthropogenic source of contamination at both landfill areas.The PN values (PN>8) highlighted landfill site and site 4 of Ghazipur landfill, and landfill site and site 2 of Narela–Bawana landfill as the most polluted locations among all sampling sites. The Igeovalues (Igeo=0–5.16) further indicated varying degrees of heavy metal contaminationacross the study sites of both the landfills except Cr, Ni, and Fe.The Wilcoxon rank-sum test revealed no statistically significant differences in concentration of most heavy metals between Ghazipur and Narela-Bawana landfill areas (p > 0.05) suggesting similar soil contamination profiles. The overall result of this study highlights the need for regular monitoring, and efficient leachate treatmentalong with site-specific remediation approaches in both the landfills.