The organic matter content of street dust in Liverpool, UK, and its association with dust magnetic properties

The organic matter content of street dust in Liverpool, UK, measured by means of the loss-on-ignition method, is 4.0% on average (standard deviation 1.3%). The magnetic measurements of the street dust samples indicate that the dominant magnetic component is multidomain grains of ferrimagnetic minerals and that superparamagnetic and stable single-domain ferrimagnetic grains and paramagnetic, diamagnetic, and canted antiferromagnetic minerals are present in small magnetic concentrations. Our study demonstrates good linear correlations between the organic matter content and some magnetic mineral concentration-related parameters: low-frequency susceptibility, frequency-dependent susceptibility, susceptibility of anhysteretic remanent magnetisation, and high-field susceptibility. Among them, frequency-dependent susceptibility shows the strongest correlation, suggesting that soil may be an important source of dust organic material. Finally, it is suggested that simple, rapid, and non-destructive magnetic measurements may be used as proxies for the organic matter content in street dust.