Geochemical differences between Gobi surface soil and transported dust: Implications for dust provenance identification in northern China's Gobi deserts

Abstract

Dust storms are an important consequence of aeolian sediment emissions and transport processes on Earth and other planets. Dust geochemistry and provenance are important issues for aeolian and environmental science researchers because both properties identify source areas that may require ecological restoration to reduce the formation of future dust storms. Although there have been many studies of dust geochemistry and provenance in China and elsewhere, most of the analysed dust was collected from the surface soil and was not transported dust. However, particle selection by the wind and subsequent sorting changes the geochemistry of the transported dust in the air. Unfortunately, there have been few studies documenting this difference. In the present study, we collected transported dust in northern China, and used the analysis of variance method to analyse the dust geochemistry to detect differences among land surfaces and in the near-surface transported dust and dust at heights of 0.25 and 1.5 m above the surface. We found that Sc, V, Zn, Y, Zr, Nb, Cd and Cs and all REE concentrations differed between surface dust and transported dust at 1.5 m height. Zr, Y, Lan, Cen, LREE concentrations and Nd/Sm ratios of REEs were larger in the surface soil than in transported dust. Dust geochemistry at heights ≥ 0.25 m was comparable in source and deposition regions, indicating that the characteristics of transported dust are a suitable indicator for dust provenance identification. Our results also indicate that the Hexi Corridor Desert and the Heihe River Basin are primary dust sources for downwind regions.