Discriminating sources of anthropogenic heavy metals in urban street dusts using magnetic and chemical methods

Abstract

Discriminating between different sources of natural and anthropogenic pollution is a topic of scientific interest, but also important for sociopolitical and economic reasons. To contribute to potential application of magnetic measurements for evaluating industrial pollution in urban environment from multi-anthropogenic sources, characteristics of street dust from a typical fast developing industrial city (Loudi, Hunan province, China) were studied by magnetic and non-magnetic (microscopic, chemical and statistical) methods. Anthropogenic magnetic spherules and iron from a Fe-smelting plant and traffic-related angular-shaped particles were identified. Heavy metals originate from different anthropogenic activities; Fe, Co, and Mo from the Fe-smelting plant; Cu and Ni from vehicle traffic; Pb, Zn and Cd from both above anthropogenic sources; Cr, Ni and Be from other anthropogenic activities. The degree of heavy metal pollution in street dust is controlled by locations of anthropogenic activities and main wind directions. Although correlation of the Tomlinson pollution load index of anthropogenic heavy metals with mass-specific magnetic susceptibility (χ) values is only moderate, our study demonstrates that magnetic proxies provide a rapid means for detecting and outlining regions with possible higher heavy metal contamination caused by multi-anthropogenic pollution sources in urban cities.