Relationship between magnetic properties and heavy metal contamination of street dust samples from Shanghai, China

Abstract

In this study, for exploring the relationship between selected magnetic properties and heavy metal contamination of street dust in Shanghai, China, 160 samples from five different functional areas (industrial, high traffic density, commercial, residential and "clean" area) were collected and investigated by magnetic and geochemical analyses. It is found that the street dust exhibits a high concentration of ferrimagnetic minerals, which are predominantly coarse-grained. Meantime, the magnetic properties of the street dust samples exhibit significant differences between the five functional areas, namely, the values of χ_lf, SIRM, χ_ARM, and S_{− 300 mT} in the five functional areas all decrease in the following order: industrial > commercial > high traffic density > residential > clean. Calculation of enrichment factors (EF) and the Tomlinson pollution load index (PLI) indicates that the street dust samples are highly polluted in terms of their degree of heavy metal contamination. The values of χ_lf, SIRM, and χ_ARM are significantly correlated with Pb, Cu, Zn, Ni, Mn, Cr, Ba, and Fe concentrations as well as PLI. In accordance with similar findings in other urban areas, these results indicate that magnetic parameters, such as χ_lf, SIRM, χ_ARM, can be used as an efficient proxy for heavy metal pollution and anthropogenic activities in Shanghai. In addition, the results demonstrate that it is possible to distinguish different heavy metal pollution sources using a combination of magnetic measurements and geochemical analysis.

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