Publication Date:
2018-06-18
Description:
The characteristics of urban dust aerosols and the contributions of their natural and anthropogenic sources are of scientific interest as well as being of substantial sociopolitical and economic concern. Here we present the results of a comprehensive study of dust flux and magnetic signatures, including magnetic susceptibility (χ) and the morphology and elemental composition of magnetic particulates, of atmospheric dustfall originating from natural dust sources in East Asia and local anthropogenic sources in Xi'an, China. The results reveal a significant inverse relationship, on a seasonal basis, between variations in dust flux and χ. By comparing χ records of desert surface sediments and local polluted dust, the relative contributions of natural and anthropogenic sources can be estimated for the urban atmospheric dustfall. Analysis using Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) indicates that magnetic particulates from different sources have distinctive morphological and elemental characteristics. Detrital magnetic particles originating from natural sources are characterized by relatively smooth surfaces with Fe and O as the major elements and a minor contribution from Ti. The anthropogenic particles have angular, spherule, aggregate, and porous shapes with distinctive contributions from marker elements, including S, Cr, Cu, Zn, Ni, Mn and Ca. Our results demonstrate that this multidisciplinary approach is effective in distinguishing dust derived from distant natural sources and local anthropogenic sources, and for quantitative assessment of the contributions of the two end-members.
Electronic ISSN:
1680-7375
Topics:
Geosciences
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