Influence of soil pH and organic carbon content on the bioaccessibility of lead and copper in four spiked soils

Exploration of the association between heavy metal bioaccessibility (BAc) and soil properties is essential for rationalization of risk assessment and remediation of contaminated soil; however, the high complexity of soil systems often yield conflicting outcomes. To avoid erroneous conclusions, individual comparisons of soil properties is essential. Herein, we determined the changes in the BAc of Pb and Cu with the variation in soil pH and SOC content using Unified Bioaccessibility Research Group of Europe method, and validated these findings with in vivo mouse bioassays. Results indicated that the BAc of Pb and Cu in gastric and intestinal phases decreased by 1.76%–3.92% and 0.90%–3.27%, and by 0.41%–6.01% and 0.67%–1.59%, respectively, with every unit increase in soil pH. Furthermore, with every 1% increase in the absolute content of SOC, the BAc of Pb and Cu decreased by 4.04%–13.94% and 4.01%–34.7%, and by 8.98%–30.15% and 9.58%–20.03%, respectively. The in vivo bioassays results confirmed decrease in Pb concentrations in the liver, kidney, and blood of mice with the increase in Ferralosol pH and SOC content. These findings revealed that the health risks associated with accidental exposures to Pb- and Cu-contaminated soils with high pH and SOC level were relatively low, and the consistent in vivo and in vitro results for the BAc of Pb and Cu suggest the requirement for a swift and simple approach for assessing the risks of heavy metal contaminated soils. Thus, this study enhanced our understanding of the variations in risk assessments with soil properties of Pb- and Cu-contaminated soils, highlighting the role of soil characteristics in health risk assessment and remediation of contaminated soils. [Display omitted] •Pb and Cu bioaccessibility decreased with increasing soil pH and SOC.•Acid-soluble metal transformed to reducible, leading to decreasing bioaccessibility.•In vivo bioassay showed a reduction in Pb-absorption with increasing pH and SOC.