MAGNETIC SUSCEPTIBILITY AND HEAVY METAL CONCENTRATIONS OF STREET DUST IN XUCHANG CITY, CHINA

Spatial characteristics of magnetic susceptibility and heavy metals in street dust in Xuchang city were analyzed and the relationships between them discussed. The results show that magnetic susceptibility of street dust ranges from 98.33-600.92x10(-8)m(3)/kg, with an average value of 334.89x10(-8).m(3)/kg, the frequency of magnetic susceptibility ranges from 0.20-5.13%, with an average of 1.82%. The high magnetic susceptibility values and the low frequency of magnetic susceptibility suggest that the magnetic materials in the street dust mainly deposited as a result of human activities. Ni, Co, Mn and As levels in street dust are lower than the background, while the levels of Cu, Pb, Zn and Cr are 1.80, 2.14, 2.42 and 1.52 times greater than the background, respectively. Magnetic susceptibility and heavy metal spatial distribution both showed a decreasing trend from northwest to southeast, reflecting the different degrees of contamination. However, the correlation between those two parameters is not significant, which is contrary to the results of previous research, suggesting that if the magnetic susceptibility and heavy metal content in street dust are below a certain level, the correlation between them is not very significant. In this case, the magnetic susceptibility cannot be used to indicate the level of heavy metal pollution in street dust.