Study on the correlation of magnetic properties and heavy metals content in urban soils of Hangzhou City, China

This work studies the correlation between magnetic properties and the content of Cu, Zn, Cd and Pb in urban soils of Hangzhou, Eastern China. The magnetic measurement shows that urban topsoils (0-5 cm) have strong magnetic susceptibility and remanence. Magnetic concentration-related parameters chi, ARM, IRM20 (mT), Hard IRM and SIRM are found to increase in the order of industrial area > roadside > residential approximate to campus > public parks, thus indicating that these magnetic components are associated with the industrial activities, automobile exhaust and deposition of atmospheric particulate. It was measured that the frequency-dependent susceptibility (chi(fd)) of urban soils is in a range from 0.7% to 8.4%. The lowest chi(fd) value with a mean value of 2.3% and 2.5%, respectively, was found in the industrial and roadside soils. The urban soils have high content of Cu, Zn, Cd and Pb. We found that the degree of contamination is increased in the order of industrial area > roadside > public parks > residential approximate to campus for Cu and Pb, and in the order of industrial area > roadside > residential approximate to campus > public parks for Zn and Cd. Results demonstrated a straight linear correlation between the magnetic mineral concentration-related parameters and the concentrations of Cu, Zn, Cd and Pb. It was found that the correlation coefficients of the magnetic parameters and heavy metal concentration are high for Zn, medium for Pb, and low for Cu and Cd. This finding suggests that the simple, rapid and non-destructive magnetic measurement can be used as an indicator for the heavy metal contamination and proxies for the measurement of heavy metals content in urban soils. (c) 2005 Elsevier B.V. All rights reserved.