Different contributions of crystalline and non-crystalline iron (hydr)oxides on the mobilization and thionation of diphenylarsinic acid in a flooded paddy soil.

Iron reduction impacts the mobilization and thionation of diphenylarsinic acid (DPAA) in soil, but the contribution of crystalline and non-crystalline iron remains unknown. A paddy soil deficient in non-crystalline iron (P-Fe), crystalline and non-crystalline iron (P-Fe) were incubated with sulfate-plus-lactate, and the results were compared with paddy soil (P) in our previous study. For treatments without ferrous sulfide (FeS) precipitation, the solution-to-solid ratio (R) of DPAA increased slightly and dramatically with iron reduction, respectively, for P-Fe and P, suggesting that the reduction of non-crystalline iron contributes more to DPAA mobilization than crystalline iron.