Spatial variations and abundances of trace metals as linked to landuse pattern: a case study from Gurugram, Haryana, India

Abstract

Surface soil samples (n = 36) from different land use areas (rural, industrial, commercial and residential) of Gurugram were studied for physicochemical properties and trace metal (Cu, Cr, Co, Ni, Pb, and Zn) abundances to identify their sources and spatial distribution over the region. Based on the results obtained, the soils of Gurugram, in general, are sandy (75–85 wt%), alkaline, and unpolluted with moderate pollution at certain sites. The average pH lies near 7.5 in all the land uses. Electrical conductivity in residential (329 μS/cm) soils is almost thrice the value in rural (87 μS/cm) soils. The primary metal of concern is Zn, which is above the permissible limits, followed by Cu and Pb. Common alumino-silicate minerals observed in the soils are quartz, K-feldspar, muscovite and sodic plagioclases. Based on the calculated average geo-accumulation index (Igeo) values of samples, soils of Gurugram, in general, are uncontaminated and have values < 1. However, a few samples are moderately contaminated. Soils show moderate contamination based on the average contamination factor values. The pollution load index, which gives cumulative pollution of all the metals for a site, suggests perfection, which means no contamination. Enrichment factor indicates minor enrichment for Cr, Cu, Pb, and Zn, whereas no enrichment for Co and Ni in all the studied sites. In health risk assessment, hazard quotient and hazard index values are < 1 and show no adverse health effects concerning non-cancer risk. Correlation and principal component analysis suggest Co, Cr, and Ni being geologically controlled while control on Cu, Pb, and Zn is mixed type i.e., both geological and anthropological. The geochemical maps show a similar spatial distribution for Cu, Pb, and Zn, which is consistent with the correlation. These metals are dominated in some commercial and residential sites. In general, soils are found to be uncontaminated based on average concentration; however, certain hotspots are observed for Cu, Pb, and Zn, which show moderate pollution and warrants early management.