See more from this Division: Topical Sessions
See more from this Session: Sources, Transport, Fate, and Toxicology of Trace Elements in the Environment II
Abstract:
Observed differences in column effluent arsenic concentrations and temporal trends during long-term leaching can be explained by the presence/absence of gravel cover. Lower total arsenic leached from the graveled column is likely due to precipitation of calcium arsenate in the soil, which was identified by XAS analysis of similar soil contaminated with arsenolite more than 50 years ago. Early in the leaching process, aqueous arsenic was dominated by As(III); however, after 180 pore volumes of acid rain leaching, As(V) began to dominate the effluent arsenic chemistry for all of the spiked columns. Speciation studies indicate that approximately one third of the As(V) was produced at the top of the column, and the remaining two thirds was oxidized in contact with soil grains. XPS analysis of the column soil sections shows oxidation of As(III) to As(V) at the arsenolite surface, decreasing soil arsenic concentrations from column top to bottom, and that arsenic sorbed to soil particles is As(V).
See more from this Division: Topical Sessions
See more from this Session: Sources, Transport, Fate, and Toxicology of Trace Elements in the Environment II