Arsenic bioaccessibility and speciation in the soils amended with organoarsenicals and drinking-water treatment residuals based on a long-term greenhouse study

Abstract

Summary Although organoarsenical pesticides are no longer applied to agricultural fields in the US, their widespread use until recently, toxicity, and potential transformation to inorganic arsenic has raised serious concern. Drinking-water treatment residuals (WTRs) have been proposed as a low-cost amendment for remediation of organoarsenical pesticide contaminated soils. A long-term greenhouse study was initiated to evaluate the effect WTR application on bioaccessibility, geochemical partitioning, and speciation of the Dimethylarsinic acid (DMA). Two soils (Immokalee and Orelia series) were spiked with DMA (1500 mg As kg −1 ) and amended with an Al- and Fe-based WTR at two rates (5% and 10% by wt.). Soil sampling was done immediately after spiking (time zero) and after 0.25, 0.5, 1, and 3 (time final) years of equilibration and subjected to bioaccessibility test and sequential extraction. Results showed that compared to the unamended (no WTR) control, As bioaccessibility in the WTR-amended soils significantly ( p p