BIOAVAILABILITY OF ARSENIC IN CATTLE DIPPING VAT SITE SOILS AS A FUNCTION OF SOIL CHEMISTRY
The present study evaluated arsenic bioavailability in cattle dip vat site soils as a function of soil properties. Twelve soil samples were selected from former cattle dip vat sites in Australia and Florida, which varied widely in terms of soil physico-chemical properties that affect arsenic retention. The soils were subjected to an in-vitro gastrointestinal (IVG) procedure to determine arsenic bioavailability. The IVG protocol consisted of a low pH stomach phase (IVGS) and a high pH intestinal phase. Absorption through the intestinal membrane was simulated using iron-oxide coated filter paper strips. Arsenic extracted by the intestinal-absorbed phases (IVGIA) and the IVGS phase was correlated with geochemical forms of arsenic. In addition, the extracted fractions (Total As, IVGS, IVGIA) were evaluated against the properties of the soil samples. Multiple regression analyses indicated that 85% of the variability in the arsenic bioavailability using the IVGS method, and 88% using the IVGIA method could be explained on the basis of variability in the soil properties considered (pH, salinity, clay content, total P, total Ca + Mg, SOM, oxalate Fe + Al). Results obtained in this study clearly demonstrate the influence of soil properties on arsenic speciation and bioavailability in contaminated soils.