天津地区土壤有机碳和粘粒对PAHs纵向分布的影响

研究了天津地区土壤中有机碳（TOC）和粘粒含量对多环芳烃（PAHs）纵向分布的影响，利用相对富集系数分析了PAHs在不同土壤深度的富集趋势。结果表明，土壤剖面中PAHs含量峰值一般在土壤的表层和次表层，并随着土壤剖面的加深而减少。土壤中有机碳含量、土壤粒度、PAHs性质和扰动、淋溶等均是影响PAHs纵向迁移的重要因素。PAHs相对富集在有机碳和粘粒含量较高的土壤中。高环PAHs主要是以与土壤有机质胶体结合的形式发生迁移，不易迁移到土壤剖面的深部，而低环PAHs则主要是以溶解态形式发生迁移，相对较易发生迁移。

The Influences of Soil Total Organic Carbon and Clay Contents on PAHs Vertical Distributions in Soils in Tianjin Area

Enrichment factors were calculated to analyze the PAHs enrichment trend at different depths of soil, and the influences of soil total organic carbon (TOC) and clay contents on vertical distribution of PAHs in soils in Tianjin area were discussed. The results showed that the concentrations of PAHs peaked at or just below the surface soil and declined with depth in various sites. The vertical distribution of PAHs was influenced by soil properties (e.g. the organic carbon and clay content), PAHs properties and the transfer mechanism (e.g. leaching and disturbances). PAHs particularly accumulated in organic carbon and clay-rich horizons. High ring PAHs mainly reached in lower soil layers associated with dissolved organic matter, or with other particles and colloids, and transfer distances were relatively short. Low ring PAHs were mainly transferred in dissolved form and easier to transfer.