珠江口中华白海豚及其食谱鱼对多环芳烃（PAHs）的暴露和健康风险的评价

The Indo-Pacific humpback dolphin (Sousa chinensis) is year-round resident in the Pearl River Estuary (PRE) and is protected as one of the first order of rare animals (The National Key Protected Wild Aquatic Animals List) in China. The contamination of polycyclic aromatic hydrocarbons (PAHs) in the PRE has engaged attention of scientists for decades. Several studies have documented high levels of PAHs in the PRE, which are mainly composed of the more toxic form of PAHs from oil contamination sources. However, the adverse impact to biota from exposure to PAHs is unclear. Cetaceans have long life spans, feed at a high trophic level and have extensive fat stores that can serve as depots for anthropogenic toxins, which support their relevance as good sentinel species to gain early warnings about current or potential negative trends and impacts of environmental contaminants to human and wildlife, yet to better characterize and potentially manage ocean health issues. In this proposal, we attempt to measure contaminant body burdens of the 16 EPA primarily controlled PAHs in multiple organ tissues of S. chinensis stranded dead in the PRE between 2003 and 2017, and consider toxicological significance of the observed contaminant concentrations on dolphin health, which allows a long-term (10 years) biomonitoring for the spatial and temporal trends of PAH exposures in biota from the PRE. On the other hand, cetaceans and humans from coastal regions have a similar route of exposure to contaminants from eating fishes, which means that health maladies from diary intake of PAHs that impact cetaceans could also impact our own well beings. As more humans inhabit coastal regions due to the fast economic development, the health assessment of our aquatic ecosystems is of vital importance. Therefore, this proposal also attempt to assess the exposure and health risks of the 16 PAHs in 10 common prey fish species by S. chinensis in the PRE.

中华白海豚是在珠江口常年栖息的鲸豚，国家一级重点保护水生哺乳动物。珠江口的多环芳烃(PAHs)污染严重，且多来源于石油，比普通PAHs更具生物毒性。但是，珠江口鲸豚暴露PAHs导致的健康风险目前还不清楚。近岸鲸豚具有较长寿命、位于食物链顶端和大量脂肪(易于富集毒物)等特点，被认为是监测和预警污染导致的现有和潜在的危害、理解海洋污染物的来源及动态的理想指示物种。本申请拟分析2003-2017年间珠江口搁浅死亡的中华白海豚组织器官样本暴露PAHs的浓度，并结合其病理信息评价PAHs对近岸鲸豚的危害，通过十年以上的长期监测反映珠江口PAHs分布的时空分布和动态趋势。此外，近岸鲸豚和沿岸居民都以河口鱼类为日常食用，通过食物暴露PAHs的途径相似。因此，本申请还拟将分析珠江口中华白海豚十种常见食谱鱼暴露PAHs的浓度并估计沿岸居民和近岸鲸豚通过食谱鱼暴露PAHs导致的危害风险。

珠江口是中华白海豚重要栖息地，其环境的严重污染被认为是导致群体衰退的重要因素。本项目主要解决了珠江口两种小型鲸豚（中华白海豚和印太江豚）对多环芳烃（PAHs）的生物差异性富集、时空变化趋势及其健康效应。通过野外搁浅的鲸豚系统解剖和取样，对2010-2017年间在珠江口沿岸搁浅的中华白海豚鲸脂、生殖器官 (睾丸、卵巢) 、大脑和印太江豚鲸脂中16种PAHs进行了定量分析。低环PAHs在大脑和生殖器有一定量的检出，证明这些化合物可以穿过血脑、血睾屏障。搁浅在PAHs污染热点的中华白海豚体内PAHs显著高于其他环境污染水平较低区域个体，证明局部海域污染能够对中华白海豚产生危害，也说明中华白海豚可作为PAHs的小尺度空间分布指示物种。多元回归模型揭示了PAHs有显著下降趋势，可能和近年来政府严格管控下PAHs在珠江口的排放得到控制有关。首次报道了PAHs沿海豚食物链富集的生物放大倍数。中华白海豚通过食谱鱼暴露PAHs的风险商较低，但类二噁英类多氯联苯其风险较高。从其组织样本中PAHs的富集水平和其病理、死因之间关系进行了研究。发现珠江口印太江豚肺部有较高的寄生虫感染率，而对于大多数中华白海豚个体则未发现明显疾病和致死因素。通过疾病-对照组比较表明，寄生虫感染江豚体内DDTs含量显著高于健康个体，而多环芳烃和其他持久性有机污染物则在两足之间不存在显著差异。该结果表明，暴露高浓度DDTs能导致江豚免疫力下降，感染寄生虫概率升高。这些结果促进了我们对PAHs及其他典型持久性有机污染物暴露对珠江口鲸豚种群健康的影响的正确认识，为其保护管理提供了可靠的科学依据。在该项目的资助下，课题负责人以第一作者共发表SCI论文5篇，其中2篇发表在环境科学领域中科院一区Top期刊Environmental Science & Technology。