Elemental composition of wind-blown sediments from contrasting textured soils

Abstract

Wind eroded sediment is sorted by height by both size and density. Less information is available about the elemental composition and enrichment ratios of these sediments. Because of that, the concentration of elements in wind-blown sediments of a sandy- and a sandy loam soil of the semiarid Argentinean Pampas were analyzed. With this purpose, a wind tunnel study was performed for obtaining the saltating sediments transported at different heights, and a sorption-based laboratory procedure was used to separate the particulate matter. Results showed that Ca and Mg were transported at low- and C and N at high heights. These tendencies were attributed to the accumulation of Ca and Mg in coarse minerals, probably apatite and Ca-feldspars, which are heavily transported by the wind, and to the accumulation of C and N in low-dense organic substances, fresh debris and polysaccharides, easily transported by the wind. Total S did not show a preference to be transported at any height, possibly due to its accumulation in organic and mineral substances. The transport of C and N was more segregated in the sandy- than in the sandy loam soil, in agreement with the better aggregation of the latter, in which some of its organic substances (carboxylic acids, amides and aromatics), form coarse and heavily transportable aggregates. From the obtained results it can be deduced that C and N would be widespread larger than Ca and Mg. Assembling of data obtained to mass fluxes, becomes relevant for modeling the biogeochemical cycles.