Association between the organic matter content and magnetic properties in street dust, Liverpool, UK

The organic matter content of street dust in Liverpool, UK, is measured for five particle size fraction and bulk samples. The content decreases signif icantly with increasing size for fractions < 300 mu m (in diameter), but th e variation is not substantial for fractions > 300 mu m The magnetic measur ements indicate that the dominant magnetic component is multidomain grains of ferrimagnetic minerals and that superparamagnetic and stable single doma in ferrimagnetic grains and non-ferrimagnetic minerals are present in small magnetic concentrations. There is a close association between the organic matter content and frequency-dependent susceptibility (chi(FD) percentage), with a significant correlation for < 63-mu m fraction samples and a highly significant correlation for > 63-mu m fraction and < 1000-mu m bulk sample s. The ratio chi(ARM)/SIRM shows a highly significant correlation with the organic matter content for <150-mu m fraction samples. This study suggests that simple, rapid, and non-destructive magnetic measurements could provide useful information about source apportionment of organic matter in street dust. (C) 1999 Elsevier Science B.V. All rights reserved.