广西廉州湾和三娘湾表层水体中多环芳烃的时空分布与来源解析

以16种优控多环芳烃（PAHs）为研究对象，分别于2017年夏季（8月）和冬季（12月）采集广西廉州湾和三娘湾的河口和海岸带14个站位的表层海水样品，利用固相萃取、气相色谱-质谱联用仪对其进行分析，探讨其时空分布、组成和来源，并评价其生态风险。结果表明：廉州湾和三娘湾河口及海岸带水体中多环芳烃单体的平均质量浓度总体上与其溶解度和极性呈正相关关系，即以2~3环芳烃为主，4~6环芳烃检出率和质量浓度均较低。PAHs总质量浓度（∑16PAHs）在夏季河口水体（72.71 ng/L）明显高于海岸带水体（56.28 ng/L）（t检验，p＜0.01），冬季河口（106.67 ng/L）与海岸带（92.43 ng/L）差异不显著（t检验，p＞0.05）。冬季河口和海岸带PAHs质量浓度均明显高于夏季。大风江和南流江PAHs的入海通量达525.3 kg/a，夏秋季占85%以上，反映了雨季河流对海岸带具有明显的影响。南流江PAHs入海通量占2条河流总量的87%以上，对廉州湾和三娘湾的影响最大。运用同分异构体比值和主成分分析方法对海水中PAHs进行来源解析，结果表明：夏季主要为燃烧源和石油源的混合来源，冬季主要为燃烧源。与其他国家或地区相比，廉州湾和三娘湾海水中PAHs质量浓度处于较低水平。生态风险评价结果显示廉州湾和三娘湾表层海水中的PAH风险较小。

Occurrence,Distribution and Source Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) in the Surface Waters of the Lianzhou Bay and Sanniang Bay,Guangxi

Concentrations of 16 PAHs in 14 surface seawater samples were analyzed with solid phase extraction and gas chromatography-mass spectrometry. These samples were collected from estuaries and coasts of the Lianzhou Bay and Sanniang Bay in summer and winter. The results show that the average concentrations of individual PAHs were positively correlated with their solubilities and polarities. Two- and three-ring PAHs were the predominant compounds, with higher detection rates and concentrations than PAHs with 4-6 rings. In summer, the mean of ∑16PAHs (total concentration of 16 PAHs) was significantly higher in the estuaries (72.71 ng/L) than at the coast (56.28 ng/L) (t-test, p<0.01). In winter, the means of ∑16PAHs between estuaries (106.67 ng/L) and the coastal zone (92.43 ng/L) were not significantly different (t-test, p>0.05). The average ∑16PAHs for both estuaries and coast were significantly higher in winter than in summer (t-test, p<0.05). The concentrations of the 2-ring and 3-ring PAHs exceeded 97% of the ∑16PAHs. The proportion of 2-ring PAHs was significantly higher in winter (85%-86%) than in summer (68%-69%), while the proportion of 3-ring PAHs was higher in summer (29%) than in winter (14%). In either season, the proportions of PAHs in the estuaries and coastal waters were similar, indicating that they have the same source, and that the rivers have a significant impact on coastal pollution. In summer, ∑16PAHs was higher in the Nanliu River (74.98 ng/L) than in the Dafeng River (58.92 ng/L); while in winter the ∑16PAHs in the Dafeng River (154.94 ng/L) were significantly higher than in the Nanliu River (90.58 ng/L). In summer, the ∑16PAHs was higher in Sanniang Bay (56.62 ng/L) than in Lianzhou Bay (55.93 ng/L). In winter, the ∑16PAHs in the Sanniang Bay and Lianzhou Bay were both about 90 ng/L, which were 1.5 and 1.7 times higher than their corresponding concentrations in the summer. Whether in summer or winter, the PAHs in Sanniang Bay and Lianzhou Bay mainly consisted of 2-ring and 3-ring PAHs, accounting for over 90% of the total. Five-ring PAHs were only detected in Sanniang Bay. The total flux of 16 PAHs in the two rivers was 525.3 kg/a. The rainy season contributed more than 85% of the total flux, reflecting the apparent impact of the rivers on the coast during the rainy season. The Nanliu River discharged more than 87% of the total flux of the 16 PAHs for the two rivers, because of its massive runoff. The results of source analysis using principal component analysis and isomer ratio analysis both showed that the PAHs in the surface waters of Sanniang Bay and Lianzhou Bay were from mixed sources of combustion and petroleum in summer, but mainly from combustion sources in winter. Compared with other countries or regions worldwide, the levels of PAHs in Lianzhou Bay and Sanniang Bay were moderate. The ecological risk assessment results showed that the ecological risk from the PAHs in this study was low.