Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Predicting arsenic solubility in contaminated soils using isotopic dilution techniques.
AU - Tye, A. M.
AU - Young, S. D.
AU - Crout, N. M. J.
AU - Zhang, Hao
AU - Preston, S.
AU - Bailey, E. H.
AU - Davison, William
AU - Mcgrath, S. P.
AU - Paton, G. I.
AU - Kilham, K.
PY - 2002/3/1
Y1 - 2002/3/1
N2 - 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 solidsolution equilibria of As in the microcosm soils was described by a simple model based on competition between HAsO42- and HPO42- for “labile” adsorption sites.
AB - 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 solidsolution equilibria of As in the microcosm soils was described by a simple model based on competition between HAsO42- and HPO42- for “labile” adsorption sites.
U2 - 10.1021/es0101633
DO - 10.1021/es0101633
M3 - Journal article
VL - 36
SP - 982
EP - 988
JO - Environmental Science and Technology
JF - Environmental Science and Technology
SN - 0013-936X
IS - 5
ER -