Revisiting the remediation of arsenic-contaminated agricultural soil: a review of real-world testing

Agricultural soil affected by metal(loid) contaminants not only endangers food safety but also causes environmental pollution and soil health degradation. Unlike degradable organic pollutants, metal(loid)s, including arsenic (As), are non-degradable and only shift between environments. The Earth’s As amount remains constant, raising the question of whether we should dilute or concentrate it. To address this, we examined real-world soil remediation outcomes for insights. We have collected data from ~30 agricultural soil remediation projects in the world, with the longest operation time being 15 years. Based on their effect on As distribution, the As-contaminated soil remediation technologies were divided into three categories: concentration, dilution, and no change. Impacts of these three scenarios on food safety, soil As concentration, and bioavailability were analyzed. Post-remediation, the agricultural produce derived from these soils consistently meets the pertinent national standards. Scenario simulation was made at the regional scale, comparing the outcomes of soil remediation technologies, specially focusing on the distribution of As. Taking into account the results from different scales, we propose that dilution could be a viable alternative to concentration or no-change approaches for remediating low-As-contaminated agricultural soils.