珠江广州河段水环境中多环芳烃的组成及其垂直分布特征

Vertical Distribution,Composition of Polycyclic Aromatic Hydrocarbons in Water Column from Guangzhou Channel in the Pearl River

对珠江广州河段白鹅潭水域采集水柱一条,并按6层采集水样,根据美国EPA标准对多环芳烃进行了定量分析。结果显示,广州河段水环境中多环芳烃和16种优控多环芳烃浓度范围分别为2602.4～5145.2ng/L和987.1～2878.5ng/L;颗粒相和溶解相多环芳烃的含量范围分别为1249.3～3614.9ng/L和919.6～2848.8ng/L。多环芳烃垂向分布特征具有环数越高,其在水柱中下层水体中的含量越高特征,表明水柱可明显分为上层和中下层两层水体,两层水体多环芳烃的组成、污染物的输入方式均有较大的差异,中下层水体高环数的多环芳烃与河口水动力条件密切相关;初步分析表明在涨、落急过程中随流速加大可能引起表层沉积物再悬浮作用造成二次污染。

Six water samples from different depths in water column from Guangzhou channel in the Pearl River were collected on Oct, 17, 2001 and filtered by GF/F glass fiber filter. Polycyclic aromatic hydrocarbons （ PAHs ）, including parent, alkylated and sulfur/oxygenated PAHs were identified and measured based on USEPA 8000 series methods and under quality assurance and quality control （QA/QC）. Concentrations of total PAHs and 16 PAHs varied from 2 602.4 to 5 145.2 ng/L and 979.2 to 2 876.2 ng/L respectively, and the particulate phase PAHs were from 1 249.3 to 3 614.9 ng/L and 919.6 to 2 848.8 ng/L in dissolved phase respectively. With the increasing of high molecular weight PAHs, the elevated concentrations of particulate phase PAHs with the increase of water depth were found in the water column. The composition and inputs of PAHs were different between the surface water and the median-bottom water in the water column. The composition and inputs of PAHs in the median-bottom water were correlated with the changes of dynamics, and it was indicated that the resuspension of surface sediment potentially occurred with the increasing of rapid current in flood tide or ebb tide; and the resuspension of surface sediment will induce the secondary pollution of PAHs to the aquatic environment.