Metal contamination and bioremediation of agricultural soils for food safety and sustainability

Agricultural soil is a non-renewable natural resource that requires careful stewardship in order to achieve the United Nations' Sustainable Development Goals. However, industrial and agricultural activity is often detrimental to soil health and can distribute heavy metal(loid)s into the soil environment, with harmful effects on human and ecosystem health. In this Review, we examine processes that can lead to the contamination of agricultural land with heavy metal(loid)s, which range from mine tailings runoff entering local irrigation channels to the atmospheric deposition of incinerator and coal-fired power-plant emissions. We discuss the relationship between heavy metal(loid) biogeochemical transformations in the soil and their bioavailability. We then review two biological solutions for remediation of contaminated agricultural land, plant-based remediation and microbial bioremediation, which offer cost-effective and sustainable alternatives to traditional physical or chemical remediation technologies. Finally, we discuss how integrating these innovative technologies with profitable and sustainable land use could lead to green and sustainable remediation strategies, and conclude by identifying research challenges and future directions for the biological remediation of agricultural soils. Contamination of agricultural soils by heavy metals and metalloids has severe consequences on human and ecosystem health. This Review discusses the sources of heavy metal(loid) contamination, the mechanisms by which these contaminants interact with biological and geochemical soil elements, and plant-based and microorganism-based remediation strategies.