Cutting-edge approaches in remediating soils co-contaminated by heavy metals and polychlorinated biphenyls: current progress and future directions

Soil contaminated with heavy metals (HMs) and polychlorinated biphenyls (PCBs) poses significant threats to human health and the ecological environment, attracting widespread attention. Although various methods have been developed to concurrently reduce these pollutants, a critical review of HMs-PCBs co-contaminated soil remediation is still lacking. This study aimed to fill this gap by systematically reviewing the progress made over the past decade. It began with an investigation of the sources and current status of HMs-PCBs co-contaminated soils, summarizing site characteristics and revealing correlation between the concentrations of strongly oxidative/reductive HMs and PCBs. The review then summarized the diverse remediation strategies for soil HMs-PCBs, focusing on the mechanisms of reduction, oxidation, and biological treatments. Particular emphasis was placed on synergistic remediation strategies, including biological, physicchemical-biological and physicchemical complementary approaches, highlighting the advantages of integrated methods, such as combining vegetation and microbial remediation, in minimizing environmental disturbance. Finally, the study identified challenges and future directions, including the development of new materials, the need for practical field applications, and further research into combined technologies and their interactions. This review provides essential insights and technical guidance for addressing the complex issue of HMs-PCBs co-contaminated soil remediation.