Abstract:

Qinzhou Bay, situated at the northern extremity of the Beibu Gulf, encompasses the Maowei Sea to the north and the outer bay to the south. It is a typical subtropical estuarine bay characterized by distinct marine ecosystems, such as mangroves, salt marshes, seagrass, and oyster reefs. Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants that are toxic to ecosystems and persist in their environment. This study aimed to understand the pollution status of PFAS in this region and their ecological risks to marine ecosystems. 36 PFAS were detected and analyzed in the surface and bottom seawater samples, and the ecological risk assessment of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) was performed using the risk quotient (RQ) method. The results showed that the total concentration of PFAS (∑PFAS) ranged from 4.57 to 13.55 ng·L⁻¹, which was at a medium to low levels among coastal bays in China. Hexafluoropropylene oxide dimer acid (HFPO-DA), 2-[2-(trifluoromethoxy) hexafluoropropoxy] tetrafluoropropanoic acid (HFPO-TA (C7)), and perfluorobutanoic acid (PFBA) are the three dominant pollutants. The spatial distribution findings suggested that the ∑PFAS in the surface seawater of the Maowei Sea exhibited a decreasing trend from the western region towards the eastern coastal area. Conversely, ∑PFAS in the bottom seawater showed an opposite trend. In the outer bay, the ∑PFAS in the surface seawater decreased from the northeastern coast near Sanniang Bay to the southwest, whereas the concentration in the southeastern region of the bottom seawater remained relatively low. Spearman correlation analysis suggested that perfluoro-2-methoxyacetic acid (PFMOAA) and perfluoro (3,5,7-trioxaoctanoic) acid (PFO3OA) in the surface seawater may originated from a common source. Furthermore, the ecological risk assessment revealed that the mean RQ values of PFOS and PFOA were far below the threshold of 0.1, indicating low risk to the marine ecosystem of Qinzhou Bay. Considering the high levels and deficiency of ecotoxicological data for HFPO-DA and HFPO-TA (C7), it is necessary to investigate the environmental behaviors and ecotoxicological effects of these emerging PFAS.

Key words: PFAS, HFPO-DA, subtropical bay, distribution characteristics, ecological risk assessment

摘要：

钦州湾位于北部湾顶部，由北部的茅尾海和南部的外湾组成，是典型的亚热带河口型海湾，拥有红树林、盐沼、海草床和牡蛎礁等典型海洋生态系统。全氟/多氟烷基化合物（PFAS）是典型的新污染物，具有生物毒性且不易降解。为阐明该区域PFAS的污染状况及其对海洋生态系统的影响，分析了钦州湾海水中36种PFAS，并采用熵值法（RQ）评估了全氟辛酸（PFOA）和全氟辛烷磺酸（PFOS）的生态风险。结果表明，PFAS总质量浓度范围是4.57-13.55 ng·L⁻¹，在国内海湾中处于中低水平。六氟环氧丙烷二聚体（HFPO-DA）、六氟环氧丙烷三聚体（HFPO-TA（C7））和全氟丁酸（PFBA）是3种主要的PFAS。空间分布结果表明：茅尾海表层海水中PFAS总浓度由西向东递减，而底层海水中PFAS总浓度的空间分布特征与之相反；外湾表层海水中PFAS总浓度从东北沿岸近三娘湾处向西南方向递减，底层海水中东南区域PFAS的总浓度较低。Spearman相关分析结果表明表层海水中全氟-2-甲氧基乙酸（PFMOAA）和全氟-3,5,7-三氧基辛酸（PFO3OA）可能具有共同的来源。通过生态风险评估，PFOS和PFOA在钦州湾海洋生态系统中呈现出低风险。目前缺乏HFPO-DA和HFPO-TA（C7）的毒理数据，鉴于其较高的浓度水平，亟需进一步研究评估其生态风险。

关键词: 全氟/多氟烷基化合物, 六氟环氧丙烷二聚体, 亚热带海湾, 分布特征, 生态风险评估