Hazardous effects of heavy metal toxicity on soil and plants and their bioremediation: a review

Heavy metal-polluted soils have grown ubiquitous worldwide due to increased geologic and anthropogenic activity, and the plants growing in these soils exhibit decreased growth, performance, and yield. Contaminated soil with heavy metals has become a concern for agricultural scientists because of the progress made in agricultural product safety. Heavy metals are metalloids with biological toxicity. The most common are arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn). These metals exist throughout the terrestrial environment and have spread out due to anthropogenic and natural activities. Soil heavy metal pollution leads to human health risks, groundwater pollution, plant phytotoxicity, and a decline in crop and soil production. Bioremediation is an effective method of treating heavy metal-polluted soils. It is a widely accepted method that is mostly carried out in situ; hence it is suitable for the establishment/reestablishment of crops on treated soils. Using plants in the treatment of polluted soils is a more common approach in the bioremediation of heavy metal-polluted soils. Bioremediation ensures a more efficient clean-up of heavy metal-polluted soils. However, the success of this approach largely depends on the species of organisms. This paper is aimed to review the hazardous effects of heavy metal toxicity on soil and plants and their bioremediation. This paper also discusses numerous strategies for addressing heavy metal contamination in soil. Keywords: heavy metals, anthropogenic sources, natural sources, bioremediation