Behavior, risk, and bioremediation potential of heavy metals/metalloids in the soil system

Abstract

The application of pesticides and chemicals in agriculture and industrialization occasioned in meagre soil quality, which has a serious global concern. The most prevalent type of soil pollutants is inorganic contaminants, metals–metalloids, and organic pollutants like herbicides, pesticides, and polycyclic aromatic hydrocarbons. Even though heavy metals are essential for sustaining soil health, a slight increase in their concentration beyond the permissible limit can harm the soil. These metals cannot be degraded entirely but can be changed from highly toxic to less poisonous by chemical or biological methods. Further, the mobility of pollutants in soil-based environments might be increased due to competition among other heavy metal species for their available adsorption on the soil matrix. These heavy metals are hazardous in high concentrations to plants and animals. In addition to hindering nutrient uptake and limiting seed germination, excessive metal exposure also causes shoot growth to slow down, and lipid peroxidation occurs. In the present article, we see how these heavy metals accumulate continually in the soil and are later absorbed by plants. To appraise the impact of contamination and toxicity by the heavy metals in soil, their fate, transport, and toxicity mechanisms in soil systems have been described. The bioremediation strategies such as biosorption, siderophore formation, phytoremediation, phytovolatilization, and phytostabilization have also been discussed to understand the biodegradation of metalloids. Also, microbial remediation and genetic transformation are the biotechnological aspects employed to increase the degradation efficiency of heavy metals.