Abstract: Soils around the abandoned industrial and mining area have high ecological risk due to the accumulation of heavy metals. Thus, better understanding of the pollution characteristics of heavy metals is conducive to the control of pollutant diffusion. In this study, 64 soil samples of 0-20 cm layer were collected according to the topography and water flow direction in the surrounding farmland of an abandoned smelter in Hunan Province. The diffusion risk of cadmium (Cd) was examined using the methods of inverse distance weighted interpolation (IDW), mathematical statistics, and geoaccumulation index evaluation. The results showed that obvious Cd accumulation in surrounding soils of the abandoned smelter. Soil Cd contents varied from 0.09 to6.96 mg·kg^-1, with an average of 1.18 mg·kg^-1, which exceeds the local background value for soil Cd and is about 2.95 times of the risk screening value in the Soil Environment Quality: Risk Control Standard for Soil Contamination of Agriculture Land in China. The average geo-accumulation index reached the level of medium and heavy pollution. The IDW results showed that the high-pollution area was mainly distributed on the banks of stream which was used as a pool of wastewater discharge and located in the eastern part of the survey area. Soil Cd contents decreased gradually with the distance from the smelter along the stream banks. Furthermore, soil Cd contents decreased with the distance from the smelter along the wind direction. Soil Cd contents under different land use patterns were in the order of garden > paddy field > vegetable field > bare land. These results provide a basis for the management of heavy metal emissions from industrial and mining sources.

Key words: plant-plant interaction, understory vegetation, understory removal experiment, forest management.