Arsenic Solubility in a Reduced Environment

Abstract

AbstractSoluble As levels were determined in flooded soils and found to be related to the total As content and the reduced environment obtained. The flooded soils equilibrated at 25C contained a soluble As concentration which ranged from 0.06 to 0.18 ppm when treated with 0.568 mg of As/100 g soil, applied to the soil as NaAsO2. No appreciable As was found in the samples equilibrated at 25C which had not been treated with As. The equilibration of samples at 38C resulted in much higher concentrations of soluble As. The concentration of soluble As ranged from 0.15 ppm for a sample with no added As to 0.79 ppm for a sample which received 1.135 mg of As/100 g of soil. A reduced environment resulted in a greater soluble As concentration. Samples equilibrated at 38C were more reduced than those equilibrated at 25C. The increase in soluble As at lower reduction potentials was attributed to the reduction of Fe and not the reduction of As itself. Arsine was not detected in any of the soil samples.