Magnetic properties of atmospheric pollutants collected by both nature and artificial dust receptors are increasingly used as proxy parameters for environmental analysis.To investigate whether annual growth tree rings could be used to historical study of air pollution induced by heavy metal smelting plant,microscopical observations and magnetic analyses have been subjected to tree bark and tree ring core samples adjacent to an iron smelting plant.Magnetic particles were detected both on the bark and inside trunk wood,low-temperature experiment,successive acquisition of IRM,Hysteresis loops and SIRM measurements suggest that these magnetic particles are predominated by magnetite in pseudo-single domain state; magnetic particles in tree bark samples are larger than those in trunk wood samples.Comparison of magnetic properties of tree trunk and branch cores collected from different directions and heights implies that collection of magnetic particles depends on both sampling direction and height and pollution source-facing tree trmk wood contains significantly more magnetic particles than other sides.This indicates that magnetic particles are most likely intercepted and collected by tree bark first,then enter into tree xylem tissues by translocation during growing season,and are finally enclosed in a tree ring by lignifying.Magnetic properties such as time-dependent SIRM values of tree ring cores could be contributed to historical study of atmospheric pollution produced by heavy metal smelting activities.