Heavy metal contamination in agricultural soils: Sources, speciation and remediation strategies: A Review Journal Article

Heavy metal contamination of agricultural soils is a global environmental crisis threatening food security, ecological integrity, and human health. Source apportionment studies using receptor models reveal that anthropogenic activities including fertilizer and pesticide application, atmospheric deposition, industrial emissions, and sewage irrigation account for 65 to 86% of heavy metal accumulation in agricultural soils globally. Metal speciation, assessed through sequential extraction schemes and advanced spectroscopic methods, determines bioavailability and environmental risk. The exchangeable and carbonate-bound fractions represent the most hazardous pools. Remediation strategies include established physical methods like soil washing, encapsulation, electrokinetic remediation and biological approaches such as biochar amendment, phytoremediation, and organic immobilization agents. Combined approaches, particularly phytoremediation coupled with biochar and microbial consortia, offer an effective balance of cost-effectiveness, sustainability, and long-term efficacy. This review provides a framework for integrated, site-specific soil management grounded in scientific evidence.