Magnetic properties of urban topsoil in Baoshan district, Shanghai and its environmental implication

摘要

Heavy metal contents and magnetic properties (chi_If chi_fd%) in topsoil of 123 urban sites in Baoshan District,Shanghai were detected to study the significant correlations between heavy metals and chi_If The results indicate that spatial variation of in the urban topsoil is significant: the highest chi_If of 1127X l0~(-8)m~3/kg was observed in industrial soilwhile the lowest of 18Xl0~(-8)m~3/kg in agricultural soil. Significant correlations between chi_If and chi_fd% implies the soil is dominated by anthropogenic multi-domain (MD) and stable single domain (SSD) grains. A close relationship between chi_If and heavy metal contents in the topsoil is found. chi_If values in the topsoil are excellently correlated with Zn, Cr, Mn, Cu, Pb, Cd and Fe, with the coefficients (R) of 0.665, 0.416, 0.607,0.533,0.639, 0.520 and 0.503, respectively. Those in industrialsoil, are roadside and topsoil are also significantly correlated with heavy metals; but those in the agricultural soil do not reach the significant level. It indicated that the magnetic techniques can be used for monitoring soil pollution in Shanghai.