Predicting arsenic solubility in contaminated soils using isotopic dilution techniques

Tye, A. M.; Young, S. D.; Crout, N. M.J.; Zhang, H.; Preston, S.; Bailey, E. H.; Davison, W.; McGrath, S. P.; Paton, G. I.; Kilham, K.

Abstract

An isotopic dilution assay was developed to measure radiolabile As concentration in a diverse range of soils (pH 3.30-7.62; % C = 1.00-6.55). Soils amended with 50 mg of As kg-1 (as Na2HAsO4·7H2O) were incubated for over 800 d in an aerated "microcosm" experiment. After 818 d, radiolabile As ranged from 27 to 57% of total applied As and showed a pH-dependent increase above pH 6. The radiolabile assay was also applied to three sets of soils historically contaminated with sewage sludge or mine-spoil. Results reflected the various geochemical forms in which the arsenic was present. On soils from a sewage disposal facility, radiolabile arsenate ranged from 3 to 60% of total As; mean lability was lower than in the equivalent pH range of the microcosm soils, suggesting occlusion of As into calcium phosphate compounds in the sludge-amended soils. In soils from mining areas in the U.K. and Malaysia, radiolabile As accounted for 0.44-19% of total As. The lowest levels of lability were associated with extremely large As concentrations, up to 17 000 mg kg-1, from arsenopyrite. Soil pore water was extracted from the microcosm experiment and speciated using "GEOCHEM". The solid-solution equilibria of As in the microcosm soils was described by a simple model based on competition between HAsO42- and HPO42- for "labile" adsorption sites.

Citation

Tye, A. M., Young, S. D., Crout, N. M., Zhang, H., Preston, S., Bailey, E. H., Davison, W., McGrath, S. P., Paton, G. I., & Kilham, K. (2002). Predicting arsenic solubility in contaminated soils using isotopic dilution techniques. Environmental Science and Technology, 36(5), 982-988. https://doi.org/10.1021/es0101633

• Journal Article Type: Article
• Acceptance Date: Nov 21, 2001
• Online Publication Date: Feb 1, 2002
• Publication Date: Mar 1, 2002
• Deposit Date: Feb 3, 2020
• Journal: Environmental Science and Technology
• Print ISSN: 0013-936X
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 36
• Issue: 5
• Pages: 982-988
• DOI: https://doi.org/10.1021/es0101633
• Public URL: https://nottingham-repository.worktribe.com/output/3295049
• Publisher URL: https://pubs.acs.org/doi/10.1021/es0101633