Association of black carbon with heavy metals and magnetic properties in soils adjacent to a cement plant, Xuzhou (China)

Abstract

The Content of black carbon in soils close to a cement plant of Xuzhou, China, was determined to investigate its association with the concentration of heavy metals and the values of magnetic parameters. Black carbon content varied from 4. 4 to 25.2 mg/g, with an average value of 12.4 mg/g. The concentration of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn was, on average, 0.8, 22.3, 235.8, 71.08, 1796.9, 88.4, 56.6 and 216.5 mg/kg, respectively. The average values of magnetic parameters such as the mass specific magnetic susceptibility, frequency susceptibility, susceptibility of anhysteretic remanent magnetization and saturation isothermal remanent magnetization were 83.5 × 10−8 m3/kg, 6.1%, 135.0 × 10−8 m3/kg and 1067.0 × 10−5 Am2/kg, respectively. Black carbon content showed significant positive correlation with the concentration of Cd, Co, Cu, Pb and Zn in soils, indicating that these metals were likely to be retained by black carbon. Significant correlations between black carbon content and magnetic parameters including magnetic susceptibility, susceptibility of anhysteretic remanent magnetization, saturation isothermal remanent magnetization together with interparametric ratios were also found. Cluster analysis and principal component analysis were used to further demonstrate the relationships between the above-mentioned variables, showing that cement plant emissions are the main source of black carbon in soils. These results provide the possibility for monitoring black carbon pollution with environmental magnetism methods.