Magnetic properties of tree leaves and their significance in atmospheric particle pollution in Linfen City, China

Abstract

Fifty-one tree leaves were sampled in the industrial area, residential area, and Fenhe River ecological zone, for the purpose of a magnetic study on atmospheric pollution in Linfen City, Shanxi Province, China. Measurements of mass-specific magnetic susceptibility (γ) show a significant variation range (from 11.6 × 10−8 m3/kg to 129.7 × 10−8 m3/kg). Overall values of magnetic susceptibility decline in the following sequence: industrial area > residential area > Fenhe River ecological zone. The relatively elevated concentration-related magnetic parameters (saturation isothermal remanent magnetization, anhysteretic remanent magnetization and magnetic susceptibility) appear in the industrial area, with their highest values in the vicinity of Linfen Steel Mill. Magnetic particles are dominated by multidomain, magnetite-like minerals. Magnetic particle concentration and grain size both decrease with the increasing distance from industrial area, indicating the industrial area, especially Linfen Steel Mill, is the main source of atmospheric particle pollution. Residential area and Fenhe River ecological zone are also affected by industrial emission to a certain extent. The results of this study indicate that magnetic measurements of tree leaves are practicable for monitoring and determination of atmospheric pollution in Linfen City.