SREL Reprint #2747

Arsenic in field-collected soil solutions and extracts of contaminated soils and its implication to soil standards

Walter W. Wenzel1, Anton Brandstetter1, Helmut Wutte1, Enzo Lombi2, Thomas Prohaska3,
Gerhard Stingeder3, and Domy C. Adriano4

1Institute of Soil Science, University of Agricultural Sciences Vienna -BOKU,
Gregor Mendel Straße 33, A-1180 Vienna, Austria
2Soil Science Department, IACR-Rothamsted, Harpenden, AL5 2JQ Herts, UK
3Institute of Chemistry, University of Agricultural Sciences Vienna -BOKU,
Muthgasse 18, A-1190 Vienna, Austria
4Savannah River Ecology Laboratory, The University of Georgia, Athens, Drawer E, Aiken, SC, 29801 USA

Summary: Large concentrations of arsenic in soils, sediments, and freshwaters require risk assessment across the Central Alps and other regions. We measured arsenic concentrations in soil samples collected from 38 sites located in the Austrian Central Alps that had been contaminated due to mining and smelter activities and geogenic mineralization. Medians and ranges of arsenic concentrations (in mg kg-1) in the soil solid phase were 77.1 (1-3000) for the total (Ast), 19.2 (0-726) for (NH4)2C2O4-extractable (Aso), 2.35 (0-169) for (NH4)2HPO4-extractable (Asp), and 0.143 (0-11.1) for (NH4)2SO4-extractable (Ass), arsenic. Arsenic concentrations in soil solutions (ASsol) collected from organic surface layers and mineral horizons at five selected sites using suction cups fitted with nylon membranes ranged from 0 to 171 µg l-1. Typically, the prevailing species of As in the soil solution was As(V). ASsol was correlated with ASs (ASsol = 0.279 + 15.6 ASs; r2=0.938; n=17) and AS (ASsol = 1.272 + 0.043 ASt; r2 = 0.833; n=17). Using these empirical models, ASsol can be predicted quite accurately based on extraction with 0.05M (NH4)2SO4 or toal arsenic concentrations in the soil. Linking these models to drinking water standards (DWS) we propose soil standards for freshwater protection that vary for ASs (mg kg-1) between 0.62 (for DWS = 10 µg l-1 WHO) and 3.19 (for DWS = 50 µg l-1). Corresponding standards for ASt (mg kg-1) are 203 (DWS = 10 µg l-1) and 1133 (DWS = 50 µg l-1). These considerations demonstrate that changes in legislation on DWS may have dramatic impact on As concentrations in soil that ware acceptable for groundwater protection.

Key Words: arsenic, soil solution, soil standards, soil contamination

SREL Reprint #2747

Wenzel, W. W., A. Brandstetter, H. Wutte, E. Lombi, T. Prohaska, G. Stingeder, and D. C. Adriano. 2002. Arsenic in field-collected soil solutions and extracts of contaminated soils and its implication to soil standards. Journal of Nutrition Soil Science 165:221-228.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).