Spatial distribution of soil magnetic susceptibility and correlation with heavy metal pollution in Kaifeng City, China

The characterization of heavy metal pollution is urgently needed in modern environmental studies. However, traditional geochemical methods for detecting soil heavy metals are rather time-consuming and expensive. In recent years, non-destructive and rapid magnetic techniques seem promising in monitoring soil pollution but it is questionable how this relates to heavy metal concentrations. Therefore, in order to understand the correlation of heavy metal pollution with environmental magnetism, magnetic susceptibility (chi(LF)) and the concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn were measured in the topsoil (0-15 cm) collected from Kaifeng City, China. In this study, the spatial distribution of heavy metals and AF, as well as the correlation between pollution load index (PLI) and chi(LF) were carried out. Results show that the contamination factor (CF) values of different heavy metals follow the order: Cd (10.48) > Zn (2.28) > Pb (1.68) > Cu (1.51) > Ni (0.81) > Cr (0.80) > As (0.65). The average pollution load index (PLI) of the metals is 2.53, representing a moderate pollution level as a whole of the city soil. In general, similar spatial distribution patterns of heavy metals and chi(LF) were found in this research, which decrease progressively from the southeast/east to the northwest/west in the study area. High concentrations of heavy metals and high levels of chi(LF) appears around the southeast, the north of the older city (within the ancient city wall), and along the Longxi-Haizhou Railway. Moreover, contents of As, Cd, Cr, Cu, Ni, Pb and Zn in soils and PLI are significantly positively correlated with their chi(LF). The results further attest that the measurement of chi(LF) is a simple, rapid and quantitative method for the assessment of heavy metal contamination of soils. When chi(LF) <= 71 x 10(-8) m(3) kg(-1), the soil is considered to be non-polluted; 71 x 10(-8) < chi(LF) <= 162 x 10(-8) m(3) kg(-1) represents slightly polluted soils; 162 x 10(-8) < chi(LF) <= 253 x 10(-8) m(3) kg(-1) 1 moderate pollution, and chi(LF) >= 253 x 10(-8) m(3) kg(-1) corresponds to heavily polluted soils. However, the standard is exclusively valid for the study area and cannot be simply transferred to other polluted areas. (C) 2015 Published by Elsevier B.V.