Distribution of heavy metals in habitation land-use soils with high ecological risk in urban and peri-urban areas

The study investigated spatial distribution of heavy metals in soils of urban, peri-urban and rural habitation land-uses, and the ecological risks associated with them in the Indian Himalayan state of Himachal Pradesh. Soils of undisturbed forest were taken as control. A total of 72 soil samples were collected and assayed by atomic absorption spectrophotometer for cadmium, chromium, lead, manganese, nickel and zinc. Positive correlations were observed between cadmium-chromium, cadmium-manganese, cadmium-nickel, chromium-manganese, chromium-nickel and manganese-nickel. Higher concentrations (mg/kg) of cadmium (4.956 +/- 0.031), chromium (17.299 +/- 0.567), manganese (76.473 +/- 0.031) and nickel (82.225 +/- 7.342) were recorded in urban land-use soils. Lead (44.882 +/- 3.202) and zinc (192.613 +/- 34.180) reported maximum values in peri-urban and rural land-use soils, respectively. Peri-urban and urban land-use soils were extremely polluted with loads of lead and cadmium, respectively. However, control site was contamination-free. High values of contamination factor and geo-accumulation index in urban and peri-urban land-use indicated contamination in order of cadmium > nickel and > zinc. Degree of contamination and associated ecological risk index were also high in urban and peri-urban as compared to rural and control soils.