The effects of organic amendments on heavy metals bioavailability in mine impacted soil and associated human health risk

Abstract

Accumulation of heavy metals in soil and agricultural products is of great concern as it not only affects crop growth and yield but also food safety and marketability. The aim of the present study was to determine the effects of different organic amendments on toxic metal uptake by radish (Raphanus sativus L.). A pot experiment was conducted using garden soil as control and the contaminated soil collected from mine dumps of chromite mine, soap stone mine, quartz mine, manganese mine. Garden and mine impacted soil was mixed with vermicompost, leaf compost and spent mushroom compost at 1:1:1 ratio following a completely randomized block design. Results indicated that highest Cd (2.62 mg kg−1) and Cr (13.6 mg kg−1) concentration was reported in chromite mine soil, while Pb (23.3 mg kg−1) and Mn (59.2 mg kg−1) concentration as recorded in soap stone mine and manganese mine impacted soil, respectively. All the growth parameters and heavy metal concentrations were significantly affected by the amendments. The pollution load assessment of different mining soil revealed that the soil was moderately to considerably polluted with various heavy metals, particularly Cd with CF, Igeo and Eri values of 2.26, 0.45 and 67.68, respectively. Mining soils with high amount of heavy metals negatively affected radish growth and yield, while organic fertilizers amendment reduced heavy metals availability, increased radish growth and minimized human health risk. Among selected organic fertilizers vermicompost was more effective and reduced Cd, Cr, Pb and Mn uptake by 32.5, 50.25, 44.50 and 42.25 %, respectively, and improved radish growth, food quality and reduce human-health risk.