河流食物网中铊的富集及营养级传递特征研究

Thallium is a highly toxic metal, which is included in the list of 13 so called “priority metal pollutants”. Increasing exploitation of mineral resources containing thallium leads to a great many by-products of thallium leaking out to the environment, resulting increasing thallium contamination burden in the river system. The Pearl River flow Yunnan, Guizhou, and Guangdong provinces in which large amount of mineral resources containing thallium being exploited. This brings many of thallium and its compounds into the river, threatening the health of the aquatic ecosystem and human being. However, less is known about the pollution ecological process and biogeochemical behavior of thallium in the aquatic ecosystem. This project is going to study thallium accumulation patterns and its trophic transfer characteristics along food web in the Pearl River, relying on Scientific Fishery Resources and Environment Observation Station of Mid-Down Stream of the Pearl River. Natural stable isotopes technology will be used to trace and construct the atlas of the food web and its trophic levels of biota in distinct thallium pollution degree sections of the Pearl River. Thallium concentration in tissue(s) of biota and its subcellular distributions will be determined and the accumulation patterns will be analyzed by multi-statistical analyses methods. Trophic transfer efficiency of thallium in different sections will be compared, and thallium accumulation patterns and trophic transfer characteristics will be revealed both in the food web and in subcellular levels. The results may enrich the knowledge of thallium pollution ecology and the biogeochemical behavior in the aquatic ecosystem, together with providing scientific basis for water ecology risk assessment.

铊是一种剧毒金属元素，居国际公认的13种“优先金属污染物”之列。随着含铊矿物资源的加大开采及铊的广泛利用，大量的铊被排放到环境中，导致河流系统铊污染负荷逐渐加剧。珠江流经我国云南、贵州、广西、广东等含铊矿物开采利用大省，吸纳了大量的铊及其化合物，威胁着流域水生态系统及人类健康。但关于铊在水域生态系统中的富集及传递规律的认识十分匮乏。本项目依托农业部珠江中下游渔业资源环境科学观测实验站平台，以珠江为研究对象，应用稳定同位素技术构建代表性河段食物网结构图谱，分析铊在不同类群、种类生物组织及亚细胞水平中的富集分布特征，比较铊在不同河段食物网中传递效应差异，从河流食物网及物种组织亚细胞水平上揭示铊的富集与传递规律。研究成果有望丰富水域生态系统铊的污染生态学和生物地球化学行为知识，同时为铊的水生态风险评估提供科学依据。

铊（Tl）是一种剧毒金属元素，居国际公认的13种优控金属污染物之列。随着含铊矿物资源的加大开采及铊的广泛利用，大量铊被排放到环境中，对河流系统带来潜在的危害。珠江流经我国云南、贵州、广西、广东等含铊矿物开采利用大省，吸纳了大量的铊及其化合物，威胁着流域水生态系统及人类健康。但关于铊在水域生态系统中的富集及传递规律的认识十分匮乏。本项目对珠江中下游（西江、北江、珠江河网和珠江入海口等区域）水体、沉积环境介质中铊的含量进行背景调查与研究，初步确定了水环境中铊的浓度在0.008 ~ 0.060 μg/L之间，沉积物中铊的含量在0.37 ~ 0.46 μg/g干重之间，基本处于背景值范围，未发现铊污染热点。珠江水生食物网中基础碳源、鱼类肌肉、水生无脊椎动物软体部中铊的含量在0.006 ~ 0.137 μg/g干重，富集系数在220 ~ 3900之间，补充完善了铊在我国水生生物组织器官中的累积特征方面的数据资料；研究发现铊在河流食物网中的累积特征以生物稀释为主，即随着营养级的升高，铊含量降低。本项目还研究了水体铊暴露对典型水生动物的急性毒性，并结合铊对9种珠江典型水生动物的急性毒性结果和物种敏感度分布模型探讨，推导出保护珠江流域水生生物的铊最大基准浓度（CMC）为 7.06 μg/L，连续基准浓度（CCC）为0.71 μg/L，研究结果为珠江流域渔业生态环境保护提供科学依据。