渤海水体中多环芳烃时空分布及来源

Spatial distribution,seasonal variation,and sources of polycyclic aromatic hydrocarbons in the seawater of Bohai Sea,China

以渤海水体中多环芳烃(PAHs)为研究对象,分别于2019年6月(春夏季)、8月(夏季)和11月(秋季)采集渤海海域的表、底层海水样品,利用气相色谱–质谱联用仪分析了水体中15种优控PAHs,并对其污染水平、单体组成、时空分布及来源特征进行了分析。结果表明,6月、8月和11月渤海表层海水15种PAHs的总浓度(∑_(15)PAHs)范围分别为10.1~67.0、3.20~24.2和6.14~21.5 ng/L,均值浓度分别为34.2±16.8、9.75±4.94和16.0±3.96 ng/L,季节性特征表现为6月>11月>8月。从存在形式看,海水溶解相中PAHs主要以低环为主,高环PAHs更易赋存在海水颗粒相中。水平分布上总体表现出近岸高、中部低的分布特征,河流输入是渤海水体中PAHs的主要来源,渤海南部海域受黄河流域河流输入影响污染尤其严重;垂直分布上春秋季节渤海表、底层没有明显的浓度差异,说明在强烈季风影响下水体垂直混合能力增强,而夏季则在中部海域形成PAHs表层浓度高、底层浓度低的现象,推测与夏季渤海中部冷水团和温跃层的出现有关。特征比值和主成分分析结果表明,多环芳烃的污染源没有明显的季节差异,化石燃料和生物质燃烧是渤海水体中PAHs的主要来源。

The occurrence of 15 polycyclic aromatic hydrocarbons(PAHs)for priority control were analyzed in the surface and bottom seawater of the Bohai Sea during June(spring-summer),August(summer),and November(autumn)of 2019.Concentrations,composition,spatial distribution,seasonal variations,and main sources of PAHs were discussed.Results showed that total PAH concentrations(∑_(15)PAHs)in surface seawater ranged from 10.1 to 67.0 ng/L in June,from 3.20 to 24.2 ng/L in August,and 6.14 to 21.5 ng/L in November,with an average concentration of 34.2±16.8,9.75±4.94,and 16.0±3.96 ng/L,respectively.PAH concentrations were significantly higher in June than in November and in August.PAHs mainly consisted of low-ring PAH congeners in dissolved phase,and of high-ring PAH congeners in the particulate phase.River input was the primary source of PAHs in the seawater of Bohai Sea.High concentration of PAHs was observed in the coastal area of the Bohai Sea and the Laizhou Bay.In June and November,no noticeable difference was observed for the vertical distribution of PAHs in the entire Bohai Sea.This indicates that the seawater was mixed well from surface to bottom owing to the strong monsoon.However,in the center of the Bohai Sea in August,an elevated level of PAHs was observed on the surface layer,and a low concentration in the bottom layer.This probably relates to the appearance of a cold-water mass and seawater stratification.No seasonal differences in PAH sources were observed,and fossil fuel and biomass burning were the main sources.