摘要
全氟烷基化合物（Perfluoroalkyl substances ，PFASs）是一类由人工合成的新型持久性有机污染物，因具有良好的化学稳定性、疏水疏油和耐热性等优良特性而被广泛的应用于工业生产和日常的生活用品中。由于该类化合物在自然条件下难以降解，造成PFASs在大气、土壤、水体甚至北极地区的冰川等环境介质、动物组织以及人体血液中广泛检出。毒理学研究表明，PFASs具有生物毒性以及不良的人体健康效应，如免疫毒性、致畸性、内分泌干扰毒性等，因此环境中PFASs的污染情况、迁移转化规律等引起研究者关注。
湖泊（含水库）是我国重要的淡水资源和饮用水源地，但随着经济的发展，湖泊流域有毒有害化学品污染形势严峻。而此问题在占我国国民经济较大比重的东北和华北地区尤为突出，此区域湖泊大多具有重要的饮用水水源地和灌溉功能，目前均受到不同程度的污染。但目前关于我国湖泊中PFASs污染方面的数据比较有限，更缺少针对湖泊PFASs污染情况的大范围的系统性的调查研究。因此本研究选择东北地区的松花湖，小兴凯湖，大伙房水库和华北地区的于桥水库，官厅水库，白洋淀，衡水湖，南四湖共8个典型湖泊作为研究区域，分析不同湖泊表层水和沉积物中PFASs的污染特征，探讨PFASs在表层水和沉积物中分布的湖泊区域性差异，通过分析PFASs在水-沉积物中的分配系数，探究PFASs在水和沉积物两相的分配行为，预测目标化合物在湖泊环境中的迁移转化规律，最后对湖泊表层水和沉积物中的PFASs进行风险评价，主要的研究成果如下：
（1）比较了东北地区3个湖泊2017年7月和2019年5月的表层水样品中PFASs 的污染特征变化，发现2019年5月采集的水样中检出的PFASs种类（10种）少于2017年7月（11-12种），PFASs的整体污染水平稍高于2017年7月，但主要污染物变化不大，还是以短链的PFASs（全氟丁基羧酸（PFBA），全氟戊基羧酸（PFPeA））和全氟辛基羧酸（PFOA）为主。
（2）分析了PFASs在东北和华北地区8个典型湖泊表层水和沉积物样品中的污染特征，发现PFASs在表层水和沉积物中的分布特征存在差异性，表层水中检出的PFASs 种类（9-12种）要多于沉积物（5-7种）；表层水中以短链PFASs（PFBA，PFPeA、全
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氟己基磺酸（PFHxS））和PFOA为主要污染物，而在沉积物中，短链PFASs的检出率较低，大多以全氟辛基磺酸（PFOS）和PFOA为主要污染物；表层水中PFASs的整体污染水平按照白洋淀(140.47-1828.54（881.88）ng.L-1)>官厅水库(179.37-415.47（264.82）ng.L-1)> 南四湖（17.82-29.17（23.14）ng.L-1）>小兴凯湖（9.20-16.54（11.29）ng·L-1）>衡水湖（6.63-17.93（10.33）ng·L-1）>松花湖（3.24-15.86（6.00）ng·L-1）>大伙房水库（3.75-5.98（4.76）ng·L-1）>于桥水库（1.42-5.78（2.60）ng·L-1）的顺序降低，而在沉积物中PFASs整体污染水平按照白洋淀（0.48-29.88（9.92）ng.g-1）>官厅水库（0.67-3.50（1.82）ng.g-1）>小兴凯湖（0.58-1.69（1.17）ng.g-1）
>衡水湖（0.59-1.29（0.99）ng.g-1）>于桥水库（0.43-1.01（0.65）ng.g-1）≈松花湖（0.36-1.07（0.63）ng.g-1）>南四湖（0.22-1.12（0.53）ng.g-1）>大伙房水库（0.22-0.65（0.33）ng.g-1）的顺序降低。
（3）将东北和华北地区8个典型湖泊表层水和沉积物中PFASs的整体污染水平与国内外其他地区作比较，发现白洋淀和官厅水库PFASs的污染水平较高，其他6个湖泊的污染水平都比较低。
（4）研究了PFASs在水-沉积物的分配行为，发现同一化合物在不同的湖泊的沉积物-水分配系数(K oc)表现出较大的差别。比如PFOA，在不同湖泊的logK oc的高低顺序为：松花湖(5.95±1.24)>于桥水库(5.15±0.49)>小兴凯湖(4.73±0.69)>大伙房水库(4.34±0.41)> 衡水湖(3.87±0.56)>白洋淀(3.15±1.48)≈南四湖(3.15±0.70)>官厅水库(1.24±0.51)。每个-CF2基团对K oc值平均贡献0.72个对数单位，相同碳链长度的全氟烷基磺酸（PFSAs）的logK oc高于全氟烷基羧酸（PFCAs）。
（5）对湖泊的PFOA和PFOS进行了生态风险评价，结果显示东北和华北地区8个典型湖泊的表层水和沉积物中的PFOA和PFOS的RQ值均小于1，说明本研究中PFOA和PFOS的浓度尚未达到对生态系统产生不良影响的水平。
关键词：东北和华北地区典型湖泊；全氟烷基化合物；表层水；沉积物；分布特征I Vdegrade
Abstract
Perfluoroalkyl substances (PFASs) is a new type of persistent organic synthetic pollutants,because of its good chemical stability, hydrophobic and oleophobic properties, and heat resistance, it is widely used in industrial production and daily necessities.Because these compounds are difficult to degrade under natural conditions, PFASs are widely detected in various environmental media(such as the atmosphere, soil, water bodies and even glaciers in the Arctic), animal tissues and human blood.Toxicological studies have shown that PFASs have biological toxicity and adverse human health effects, such as immunotoxicity, teratogenicity and endocrine disruption toxicity. Therefore, the contamination status, migration and transformation rules of PFASs in the environment have gained researchers' attention.
Lakes (including reservoirs) are important freshwater resources and drinking water sources in China. However, with the rapid economical development, the contamination status of Toxic Chemistry Substances in lake basin is very serious. This problem is particularly prominent in the Northeast and North China regions, which account for a large proportion of China's national economy. Most of the lakes in this region have important drinking water sources and irrigation functions, which are currently subject to different degrees of pollution. However, at present, the data on the pollution of PFASs in lakes in China are still limited, especially the lack of large-scale and systematic survey data.
Therefore, in this study, Songhua Lake, Xiaoxingkai Lake, Dahuofang Reservoir in Northeast of China and Yuqiao Reservoir, Guanting Reservoir, Baiyangdian Lake, Hengshui Lake, and Nansi Lake in North China were selected as study areas. The pollution characteristics of PFASs in surface water and sediments of different lakes were analyzed, and the regional differences of distribution characteristics of PFASs in different lakes were discussed.By analyzing the distribution coefficient of PFASs in water-sediment, the distribution behavior of PFASs in water and sediment was explored and discussed to predict the migration and transformation of target compounds in the lake environment.Finally, the risk assessment of PFASs in the surface water and sediments of the
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lakes was performed. The main research results are as follows:
(1) Compared the pollution characteristics of PFASs in surface water samples from three lakes in Northeast China in July 2017 and May 2019, I found that there were fewer types (10 types) of PFASs detected in water samples collected in May 2019 than in July 2017 (11-12 species),and the overall pollution level of PFASs was slightly higher than that in July 2017.But the major pollutants had not changed much, and short-chain PFASs (perfluorobutanoic acid(PFBA), perfluoropentanoic acid(PFPeA)) and Perfluorooctanoic acid (PFOA) were still the predominant compounds .
(2) The pollution characteristics of PFASs in the surface water and sediment samples of 8 typical lakes in Northeast and North China were analyzed, and the distribution characteristics of PFASs in surface water and sediment were different. The types of PFASs detected in surface water ( 9-12 species) was more than sediments (5-7 species).Short-chain PFASs (PFBA, PFPeA,Sodium perfluorohexanesulfonate (PFHxS)) and PFOA were the predominant compounds in surface water, while in the sediments, Sodium perfluorooctanesulfonate (PFOS) and PFOA were the predominant PFASs and the detection rate of short-chain PFASs were low. In surface water, the total concentration of PFASs decreased in the order of Baiyangdian Lake (140.47-1828.54(881.88) ng.L-1) > Guanting Reservoir (179.37-415.47(264.82) ng.L-1) > Nansi Lake (17.82-29.17(23.14) ng.L-1) > Xiaoxingkai Lake (9.20-16.54(11.29) ng.L-1) > Hengshui Lake (6.63-17.93(10.33) ng.L-1) > Songhua Lake (3.24-15.86(6.00) ng.L-1) > Dahuofang Reservoir (3.75-5.98(4.76) ng.L-1) > Y uqiao Reservoir (1.42-5.78(2.60) ng.L-1). While in sediment,∑PFASs decreased in the order of Baiyangdian Lake (0.48-29.88(9.92) ng.g-1) > Guanting Reservoir(0.67-3.50(1.82) ng.g-1) > Xiaoxingkai Lake (0.58-1.69(1.17) ng.g-1) > Hengshui Lake(0.59-1.29(0.99) ng.g-1) > Yuqiao Reservoir (0.43-1.01(0.65) ng.g-1) ≈ Songhua Lake (0.36-1.07(0.63) ng.g-1) > Nansi Lake (0.22-1.12 (0.53)ng.g-1) > Dahuofang Reservoir (0.22-0.65(0.33) ng.g-1).
(3) Compared the pollution levels of PFASs in the surface water and sediments of 8 typical lakes in Northeast and North China with other domestic lakes, it was found that the pollution levels of PFASs in Baiyangdian and Guanting Reservoir were higher, while the other six lakes were lower.
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(4) The distribution behavior of PFASs in water-sediment was studied, and it was found that the sediment-water partition coefficient(K oc) of the same compound in different lakes showed a large difference. For PFOA, the order of logK oc in different lakes decreased in the order of Songhua Lake（5.95±1.24) > Yuqiao Reservoir (5.15±0.49) > Xiaoxingkai Lake (4.73±0.69) > Dahuofang Reservoir (4.34 ±0.41) > Hengshui Lake (3.87 ±0.56) > Baiyangdian Lake (3.15 ±1.48) ≈Nansi Lake (3.15 ±0.70)> Guanting Reservoir (1.24 ±0.51). On average, each -CF2 group contributed 0.72 log units to K oc. The logK oc of perfluoroalkane sulfonic acids (PFSAs) with the same carbon chain length was higher than that of perfluoroalkyl carboxylic acids (PFCAs).
(5) Health risks of PFOA and PFOS in the lakes were assessed. The results showed that the RQ of PFOA and PFOS in the surface water and sediments of 8 typical lakes in Northeast and North China were less than 1 ,which suggested that the PFOA and PFOS contents in the study area may not have adverse effect on the aquatic ecosystem.
Key Words:Typical lakes in Northeast and North China; Perfluoroalkyl substances; Surface water; Sediments; Distribution characteristics
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