Arsenic(V) and vanadium(V) fractionation after its incorporation into a sandy loam soil from Pampas region, Argentina

Abstract

Arsenic is a well-known toxic substance,widely distributed, whereas vanadium is a pollutantof emerging interest. Both have been found to cor -relate positively in groundwaters, thus concern ariseson the effect of these pollutants on crops, if suchwaters are used for irrigation. We conducted a studyon the effect of aging with a typical crop soil mimick-ing soils initially irrigated with water containing Asand V. Afterwards, the soil was subjected to wet/drycycles. The fractionation of both elements at differ -ent times from the addition (onset of the experiment)was determined by a modified European CommunityBureau of Reference (BCR) method. It is found thatthe greater part of V is located in the most stable frac-tion from the onset of the experiment. This is attrib-uted to interaction with amorphous and clay minerals and the precipitation of Ca(VO3)2, which is predictedby speciation modeling. The remaining fractionsshow the expected behavior: the most labile fractiondecreases over time, that associated to oxidizableincreases with time, whereas the fraction associatedto reducible components stays approximately con-stant. Arsenic shows a lower proportion in the moststable fraction compared with V, and a higher propor-tion in the most labile, but otherwise shows similartendencies. The results suggest a low availability of Vand a higher one of As. No competence was observedbetween As and V in the experimental conditions.