Spatial Distribution of PAHs in Soils Around Coal Gangue Piles in Heshan

Soil samples were collected from different soil layers at sampling sites different in distance from the coal gangue pile and different in direction to the pile, southwest, northeast and southeast for analysis of content and spatial distribution of PAHs. Results show that all the 16 priority-controlled PAHs were detected in the soil samples. The total PAHs in the 5-15, 45-55 and 85-95cm soil layers varied in the range of 1152.0-11146.4, 241.8-4867.7 and 116.4-2666.0μg·kg^-1, respectively, posing a serious ecological risk. Horizontally, PAHs content in the soil decreased with the increasing distance of the sampling site from the gangue pile and vertically with the increasing soil depth as well. The changes along both directions started drastically and gradually slowed down. Horizontal distribution of PAHs in the soil was controlled by wind direction and gradient of slope, while vertical distribution in the soil by water solubility of PAHs and soil properties. Correlation analysis indicates that Nap, Phe, Fle, Bbf, Chr and Fla were the typical PAHs detected in the surrounding soils of the pile, and heavy ring PAHs were less affected by other pollution sources than light ring PAHs.