鄱阳湖湿地生态系统POPs污染的白鹭生物指示作用研究

Using bioindicator to assess the fate of persistent organic pollutants (POPs) in environment and their potential toxic effects for humans has attracted much more attention of international researchers. Birds are the typical organisms at the higher trophic levels in wetland ecosystem. The feathers of nestling cluster birds are performed as sentinel biomonitors of wetland pollution for both their sensitivity to environmental changes and non-destructive sampling strategies. Poyang Lake, the largest freshwater lake in China, is selected as the studying area for its famous wetland resources and lack of knowledge on POP pollution around. The feathers of nestling Little Egret (Egretta Garzetta) and their prey items, as well as the water and sediment samples collected at the same time from the corresponding foraging areas are being used for organochlorine pesticide (OCP) and polycyclic aromatic hydrocarbon (PAH) analysis. Then, the combined analysis of the bioaccumulation factors with the chemical characteristic indexes based on the concentrations of POPs observed in different environmental compartments is able to infer the bioaccumulation routes of POPs in feathers, which can also be helpful for implying the correlated relationship of POPs detected in feathers and inorganic environment. Additionally, the potential effects of prey item compositions on the bioaccumulation of POPs in feathers are evaluated by the stable isotope analyis of both feathers and prey items. Finally, considering the bioaccumulation difference of different chemicals induced by their specific physicochemical properties, we are trying to find out the most sensitive chemicals that can be well monitored with the feathers of nestling Egretta Garzetta. Therefore, the efficacy of feathers of nestling Egretta Garzetta being used as the biomonitors of both inorganic environment (water and sediment) and low-trophic level organisms from the same foraging area can be identified, which can provide basic information for their extensive application as routine bioindicators to monitor POPs in wetlands and also for further ecological risk assessment.

利用生物指示效应评价环境POPs污染程度及其对人类健康的潜在影响，是当前国际环境研究的前沿之一。鸟类作为湿地生态系统中主要的高等生物类群，其雏鸟羽毛组织因对环境较强的依赖性和取样无损伤性，成为湿地环境污染监测的敏感生物指标。本项目选取鄱阳湖湿地为研究区域，以栖息地水体/沉积物、白鹭雏鸟食物及雏鸟羽毛中OCPs和PAHs的含量赋存特征为基础，结合生物积累因子和化合物特征指数分析等,揭示典型POPs的介质传递过程和生物积累效应，考察雏鸟羽毛与水体/沉积物POPs污染赋存的相关关系；运用稳定碳氮同位素技术，阐明雏鸟食物来源组成对羽毛中POPs生物积累效应的影响；弄清不同化合物生物积累特性差异，筛选敏感目标污染物，综合评价白鹭雏鸟羽毛对湿地无机环境介质和食物链底层生物POPs污染的生物指示作用，为开展湿地生态系统POPs污染生物监测和生态风险评价提供科学依据。

本项目研究了白鹭雏鸟羽毛对鄱阳湖湿地生态系统多环芳烃（PAHs）和有机氯农药（OCPs）污染的生物指示作用。分别以鄱阳湖水域环境介质和湿地环境介质为研究对象，阐明了鄱阳湖水环境PAHs和OCPs的赋存特征，研究发现鄱阳湖湿地生态系统PAHs和OCPs污染分布广泛，丰富了研究区域POPs污染基础数据库；考察了鄱阳湖水域环境生物体以及南部、中部和北部湖段湿地白鹭雏鸟羽毛及蛋壳组织中PAHs和OCPs的生物积累效应，表明底栖动物、水生植物以及鱼类肌肉组织存在明显的生物积累现象；结合化合物生物积累系数（BAF）和环境介质主要化合物组成相关分析，发现白鹭雏鸟羽毛对湿地土壤介质OCPs污染具有较好的指示作用；通过分析不同生物体内δ13C和δ15N稳定同位素组成特征，揭示生物体食物来源特性及营养级位置，综合化合物组成相关分析及生物积累效应，研究指出HCHs、DDTs和Chlors等OCPs以及2环、3环和4环等低环数PAHs化合物存在明显的食物链放大现象，为可用白鹭雏鸟羽毛进行有效生物指示的敏感目标污染物。