Effect of Soil Aging on Cadmium Bioavailability and Bioaccessibility at a Contaminated Site

The effect of aging on cadmium (Cd) bioavailability and bioaccessibility was investigatedin naturally aged field soil within a contaminated site. The results, which are based on a comparisonof investigations carried out in 2018 and 2022 on the same soil samples, provide a realistic evaluationof the variation in Cd chemical forms due to long-term aging. The data obtained show a significantreduction (from approximately 30% to 60%) in the mobile and bioavailable forms of cadmium, whilethe total quantity in soil did not change significantly. The effect of aging on the bioavailable fractionsis also reflected in the reduction in the amount of the metal absorbed by plants. On the one hand, thisindicates a reduction in the potential contamination of the food chain, while on the other, it highlightsthe limitations of the use of phytoextraction as a clean-up technology in this specific site. In the caseunder study, it should also be noted that there was no decrease in cadmium bioaccessibility over time,which remained very high even after four years of cadmium aging in the soil, which was about 60%of the total content in the most contaminated soil samples. This highlights the potential health risksrelated to the incidental ingestion of Cd-contaminated soil, which could become the main exposureroute in the case of the final use of the site as a park or public green area.