长江口围填海土壤中PCBs的时空分布

Spatial and temporal distribution of PCBs in the reclamation soils at Changjiang Estuary

主要研究长江泥沙冲刷淤积而成的长江口围填海土壤,以上海市崇明岛为采样区域,以1974年至今的5个不同年代段的围填海土壤为研究对象,以PCBs为研究目标。在5个年代段上分别采集表层（0～15cm）和深层（100 cm）土壤,样品经过索氏提取和层析净化后,由GC-MS对其进行定量定性检测分析,从而分析多氯联苯（PCBs）的含量和组成特征。结果显示：共检出了35种PCBs组分,表层和深层土壤中∑35PCBs含量范围分别为1.954×10^-9～3.716×10^-9、2.649×10^-9～3.685×10^-9;主要是二氯联苯和四氯联苯。此外,长江口围填海土壤中PCBs的含量先呈现出上升的趋势,直至1990s后,出现下降的趋势。最后基于层次聚类分析验证得出：深层土壤和下一时期表层土壤PCBs的污染水平和污染来源保持基本一致。

This paper mainly studies the reclamation soils at Changjiang Estuary from the Changjiang River silt and the sediment areas accumulate annually. It takes the Chongming Island of Shanghai City as sampling regions and PCBs as the target analyte. The reclamation areas are divided to 5 time segments from 1974 to the present. We took the surface （0 -15 cm） and deep （100 cm） soils at 5 spots respectively, which are located at separated time intervals of sediments. After sample pretreating through Soxhlet extraction and cleansing, we analyzed PCBs qualitatively and quantitatively by GC-MS, thereafter we can specify the distribution of PCBs concentration and composition characteristics. There are 35 PCB congeners detected in both the surface and deep soil samples. The concentration ranges of E35PCBs in the surface and deep soils are 1. 954×10^-9 - 3. 716 ×10^-9 and 2. 649 ×10^-9～3. 685 ×10^-9 respectively. The majority fraction of PCBs congeners in the reclamation soil samples are DiCBs and TetraCBs. In addition, the concentration of PCBs goes up till 1990s, and then goes down afterwards. Finally, we gave a brief analysis based on the Hierarchical Cluster analysis method. The results show that the polluting extent and pollutant source of the deep soils are proved to conform to those of the surface soils in the next time period.