Impact of heavy metal pollution on some physical and chemical properties in major soil orders of India
Abstract
Heavy metal pollution poses a major threat to soil health, crop productivity and environmental safety in industrial and wastewater-affected regions of India. This study assessed the influence of industrial discharge and wastewater irrigation on soil physicochemical properties and heavy metal dynamics across three major soil orders-Alfisols (Sukinda Valley, Odisha), Inceptisols (Sonipat, Haryana) and Vertisols (Dewas Industrial Area, Madhya Pradesh). Composite soil samples were collected from polluted and adjoining non-polluted sites at two depths (0–15 and 15–30 cm). Soils were analysed for texture, pH, electrical conductivity (EC), organic carbon (OC), cation exchange capacity (CEC), total nickel (Ni), cadmium (Cd), lead (Pb) and chromium (Cr) as well as bioavailable Ni, Cd, Pb and Cr using diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) extractants. Results showed that soil physicochemical properties varied significantly among soil orders, with Alfisols being acidic, Inceptisols near neutral and Vertisols alkaline with high clay content and CEC. Pollution generally increased EC and OC but reduced CEC, particularly in Alfisols and Vertisols. Total metal concentrations increased markedly in polluted soils, especially Cr in Alfisols (256–296 mg kg-1) and Ni in Inceptisols (765–876 mg kg-1). Bioavailable fractions followed a similar trend, with polluted Inceptisols exhibiting exceptionally high DTPA-extractable Ni (9.18 mg kg-1) and Cd concentrations, while polluted Alfisols showed elevated Cr mobility. The findings highlight that industrial and wastewater pollution substantially enhance heavy metal load and mobility, altering key soil properties and increasing ecological risk. Soil order strongly governs metal retention and bioavailability, emphasising the need for order-specific monitoring, remediation and sustainable land-use strategies to safeguard environmental and food system health.