纳木错流域全氟化合物生物富集行为研究及源解析

The occurrence of Per- and Polyfluorinated Alkyl Substances (PFASs) in Tibetan Plateau has aroused great concern. However, the mechanism of long range transportation, transformation, and differential bioaccumulation behavior of PFASs between aquatic and terrestrial food chains have not been studied to date. Nam Co Basin locates in the south central of Tibetan Plateau, maintaining diversity and abundance of wild creature. It consists of an integrated wetland ecosystem, including both terrestrial and aquatic food chain. Considering there is few industry in this region, it is an ideal natural laboratory to study PFASs’ long range transportation, differential bioaccumulation behavior between aquatic and terrestrial animals as well as their transformation among atmosphere, hydrosphere, pedosphere and biosphere. This project aims to reveal the homologue profiles, sources, and differential bioaccumulation behavior of PFASs in Nam Co Basin. The major homologues of PFASs and the environmental process of long-range transportation will be studied by detecting and screening PFASs in air samples. Furthermore, the sources of PFASs will be traced in the way of analyzing their seasonal variation, in together with considering the monsoon and air mass backward trajectory. The differential bioaccumulation capacity of PFASs in both aquatic and terrestrial food chains will be simultaneously investigated for the first time, and the risk of PFASs to this ecosystem will also be evaluated. This project will fill the gap of the environmental and bioaccumulation behavior of PFASs and their alternatives in the remote plateau ecosystem. It will further provide a scientific view for selecting PFASs’ alternatives in future, and finally offer technique supports to the implementation of the Stockholm Convention in China.

全氟化合物(PFASs)在青藏高原环境中的检出受到了广泛关注，然而其长距离传输过程，在高原生态系统中迁移转化及其在水生和陆生生物中差异化富集机理至今仍无报导。纳木错流域远离人类工业生产，具备完整的水生和陆生生态系统，是研究PFASs长距离传输、多圈层迁移、差异化富集的理想天然实验室。项目拟通过甄别纳木错流域大气中PFASs组分和大气反向轨迹分析，研究PFASs长距离传输的环境过程，并对其进行源解析；通过采集水、土壤、生物等多圈层样品，研究PFASs在高原生态系统中的迁移转化和水生/陆生食物链中的差异化富集效应，并初步评价PFASs对该生态系统的潜在风险。本项目将填补PFASs在高原生态系统中环境行为的研究空白，同时将现有PFASs替代品长距离传输和生物富集能力纳入研究范畴，为PFASs替代品的选择提供科学数据支持，最终为我国履行斯德哥尔摩公约所开展的谈判活动提供数据及技术支持。

本项目立足实际环境，对青藏高原纳木错流域的各类环境介质，生态系统中的各个营养级进行了系统的采样。第一，发现纳木错多圈层样品中PFASs污染特征符合PFASs前驱体长距离传输后的氧化降解产物特征，基于降水、非冰川径流、冰川径流溶解态中PFAAs的浓度和纳木错湖1992-2004年的水文观测数据平均值，我们估算了降水、非冰川径流、冰川径流对湖泊PFASs的年输入量。第二，开发了鸟类羽毛中PFASs灵敏的分析方法，评估其是否可以作为非损伤性污染指示物，结果显示羽毛和肌肉中PFASs相关性较差，但污染水平类似。第三，PFASs在纳木错流域中污染水平较低，鱼体内污染水平在1-10 ng/g 干重之间，高营养级鹰肌肉中的污染水平在10-100 ng/g 干重之间。PFASs能在陆生食物链中能显著生物放大，尤其是短碳链的全氟化合物PFBA，在陆生食物链也具有生物放大的潜力。第四，在青藏高原纳木错流域研究了PFASs在实际环境中的迁移转化等环境行为，发现冰川消融是当地PFASs的重要二次源，进一步结合理论环境化学，建立了可快速预测不同PFASs在水体中传输的粗粒化-耗散粒子动力学模型，并成功的在纳木错流域中得到验证。本项目在研究过程中获得了纳木错多圈层介质中PFASs的赋存特征，为我国履行斯德哥尔摩公约所开展的谈判活动提供了数据及技术支持。