A review of heavy metals accumulation and control in active agricultural soil

Abstract

Agricultural soil is contaminated with dangerous heavy metals (HMs) from anthropogenic activities and natural processes. These HMs are passed to humans through the consumption of crops produced in the contaminated soil. Crop production in a contaminated field and irrigation with raw untreated sewage and industrial effluents exposed food crops to HMs contaminations. Consumption of foods contaminated with HMs can be dangerous due to their persistent nature and tendency to accumulate in human tissues. HMs contamination in humans can lead to serious health problems and, in severe cases, can cause death. This review article aimed to compile soil treatment methods reported to be effective in reducing HMs uptake by food crops in active agricultural fields, outline research gaps and suggest areas for future research. Soil treatment with biochar is the most effective control method reported, was found to mitigate the uptake of Cd, Cr, Pb, Zn, and Cu in different crops. Other control measures are the application of inorganic sorbents, chelating agents, and nanomaterials to soil and hydroponic water; the use of microorganisms and their products; gene modification of the food crop; and soil washing and filtration. The control methods reported in soil and the hydroponic solution were found to significantly lower Cd, Pb, Ni, Zn, Cu, Co, Cr, Mn, Hg, and Fe uptake in cereal grains and different types of vegetable and tuber crops.