Fixation of Arsenical Herbicides, Phosphate, and Arsenate in Alluvial Soils

Abstract

AbstractThe sorption of arsenic (as arsenate), phosphate, DSMA (disodium methanearsonate) and the sodium salt of cacodylic acid (hydroxydimethylarsine oxide) by 16 Mississippi River alluvial flood plain soils was measured in a slurry experiment in which initial pH and solute molar solution concentrations for all four solutes were identical. Sorption of the two organoarsenical herbicides was strongly correlated with arsenate and phosphate sorption, and sorption of all four species was strongly correlated with clay and iron oxide contents of the soils. In 10−3 to 10−4M solution, the arsenicals are more strongly sorbed than phosphate with sorption increasing in the order P < cacodylate < arsenate ≃ methylarsonate.