绵阳市代表性点位土壤多环芳烃剖面分布特征

VERTICAL DISTRIBUTION OF POLYCYCLIC AROMATIC HYDROCARBONS IN SOILS OF REPRESENTATIVE SPOT IN MIANYANG CITY

通过挑选绵阳市有代表性的点位土壤柱，应用GC-MS分析土壤柱垂直剖面中多环芳烃的含量水平，得出其垂直剖面分布特征。结果表明：5～20cm深度中的PAHs含量最高，40cm以下则含量锐减。由于表层（0～5cm）土壤与大气之间的土气交换频繁，PAHs含量相对较低，而5～20cm处土壤受到表层土壤的遮盖，PAHs富集较高，含量达到整个土壤柱最高值。多环芳烃总体垂直剖面分布特征表现出随深度增加含量减少的趋势。PAHs总含量以江油市点位（330．24ng／g）最高，其次是三台县点位（299．89ng／g），最低是游仙区点位（112．74ng／g）。研究区主要污染物为Nap、Phe和Chr／y。其中不同的土质、种植物都能影响PAHs的富集和迁移速率，导致含量在不同深度上产生变化。此外，参照有关环境质量标准，发现PAHs总量上江油市点位与三台县点位属于轻微污染、游仙区点位则属于无污染。

Through the selection of a representative of spot in Mianyang Economic Area,the vertical distribution of polycyclic aromatic hydrocarbons （PAHs） in soils was studied using GC-MS. The results showed that in the entire soil column,surface soils with 5-20 cm depth have the highest concentration of PAHs. In addition,the soil below 40 cm,while the concentration of PAHs reduced very fast. As the surface layer （0- 5 cm） have the frequent exchange between the soil and atmospheric,PAHs content were relatively low. The 5-20 cm depth soil was covered by surface soil,therefore the soil was enrichment PAHs fastest. Then the concentration of PAHs achieves the highest value in the whole soil column. The concentration of PAHs decreased with depth in the vertical profile. The highest concentration of PAHs was observed in the economic forest of Jiangyou City spot （330.24 ng/g） followed by Santai County spot （299.89 ng/g） and Youxian District spot （112.74 ng/g）. The principal PAHs compounds in study area were naphthalene,phenathrene and chrysene. The difference of soil and plant impact PAHs that were enrichment and transportation speed; therefore PAHs in different depths have changed. Compared with the corresponding environmental guideline values,the content of PAHs in Jiangyou City spot and Santai County spot were a bit high,and Youxian District spot was under the standard.