太湖流域典型湖泊表层沉积物中多环芳烃污染特征

Pollution Characteristics of Polycyclic Aromatic Hydrocarbons(PAHs)in the Surface Sediment from Two Typical Lakes in the Taihu Basin

持久性有机污染物引起的水质安全性问题日益受到广泛的关注,为了全面了解太湖流域湖泊沉积物中多环芳烃的污染特征,在太湖流域选择典型湖泊天目湖和太湖梅梁湾分别采集7个表层沉积物(0～2cm)样品,利用GC/MS分析了样品中16种优控多环芳烃(PAHs)。结果表明,天目湖表层沉积物中16种优控PAHs总量介于287.50～713.93ng·g-(1干质量),太湖梅梁湾表层沉积物中PAHs总量介于1690.72～5033.70ng·g-(1干质量),空间分布特征受周边区域内点源污染和河流输入污染物影响。天目湖表层沉积物TOC浓度与PAHs总量相关性比太湖梅梁湾显著。利用特征化合物指数对PAHs的来源进行判别,天目湖表层沉积物中PAHs主要来源是木材、煤燃烧,而太湖梅梁湾表层沉积物中PAHs主要来自石油、木材和煤燃烧混合来源。基于沉积物中多环芳烃的环境质量标准,太湖梅梁湾表层沉积物中PAHs生态风险远高于天目湖,但总体生态风险较低。

The safety of water resource, threatened by persistent organic pollutants （POPs）, is of great concern. To well understand the pollution characteristics of polycyclic aromatic hydrocarbons （PAHs） in lake surface sediment, the Tianmu Lake and the Meiliang Bay of the Taihu Lake in the Taihu Basin were chosen for study. Seven surface sediment samples （0-2 cm in depth ）from different localities were collected in each of the lakes. Concentration of 16 PAHs, identified as priority pollutants by the USEPA, were measured by gas chromatography equipped with a mass spectrometry detector （GC/MS）. The study results show that the total PAHs concentration ranges from 1 690.72 to 5 033.70 ng·g^-1 （dry weight）, with an average of 3 498.97 ng·g^-1 in the sediment samples from Meiliang Bay and from 287.50 to 713.93 ng·g^-l, with an average of 458.52 ng·g^-1 in the Tianmu Lake. The distribution of PAHs is found to have been influenced by riverine discharge and point-source pollution. Correlation between TOC content and the total PAHs concentration in the surface sediment from the Tianmu Lake shows a higher coefficient （R^2=0.898） than that （R^2=0.350）of the Meiliang Bay. According to the observed molecular indices, the PAHs in surface sediment from the Tianmu Lake originated largely from coal and biomass combustion in the surrounding areas, while those found in the surface sediment from Meiliang Bay in the Taihu Lake originated from mixed sources of petroleum PAHs, coal and biomass combustion. Referring to the sediment quality standards, the sediment from Meiliang Bay in the Taihu Lake possesses a slightly higher PAHs toxicity than that from the Tianmu Lake, but overall the PAHs toxicity in the sediment of the Taihu Lake is still relatively low.