Water and sediment samples in twelve monitoring sites were collected in the source region of Yangtze River in June 2017, followed by the content detection of seven metal ions, and assessment of pollution level and ecological risk with the consideration of geo-accumulation index, water quality index, and potential ecological risk index. As results, the concentrations of Mn, Ni, Cu, Zn, Cd, Pb, and Cr in water ranged among ND–4.21, 0.609–3.71, 0.033–5.01, ND–34.86, ND–0.06, ND–0.55 and 0.235–2.66 μg/L respectively, which were rather low compared with other aquatic systems. Their contents in sediment were in the range of 445.93–627.32, 10.11–17.85, 15.61–24.57, 45.40–125.20, 0.19–0.56, 14.85–235.21, and 27.94–46.18 mg/kg. Metal contents in sediment were dominated by background value, and barely impacted by physicochemical factors. Whereas natural or anthropogenic factors, such as NH₄-N, NO₃-N, SS and water temperature, displayed certain influence on ion contents in water according to correlation analysis. Results by water quality and risk assessment suggested that water quality in the source region of Yangtze River was excellent. The sediments at higher altitude area presented certain metal accumulation especially Zn, Pb, and Cd, which was perhaps due to the adjacent Pb-Zn deposits. Cd was the key factor that contributes to the potential ecological risk of sediment in the Yangtze River source. Overall, this study can fill in the gap of lacking detecting data at headwater, and provide a theoretical basis for the pollution prevention and control of heavy metals even in the whole Yangtze River basin.

于2017年6月在长江源区12个采样点采集表层水样和沉积物样品, 测定重金属含量, 并结合地累积指数、水质指数和潜在风险指数等, 评价长江源重金属污染和生态风险。结果表明, 水体中Mn, Ni, Cu, Zn, Cd, Pb和Cr的浓度范围为ND~4.21, 0.609~3.71, 0.033~5.01, ND~34.86, ND~0.06, ND~0.55和0.235~2.66 μg/L, 沉积物中重金属含量为445.93~627.32, 10.11~17.85, 15.61~24.57, 45.40~125.20, 0.19~0.56, 14.85~235.21和27.94~46.18 mg/kg, 与其他流域相比处于较低水平。长江源沉积物重金属含量由环境背景值主导, 水化学因子对沉积物中重金属分布的影响较小; 在不同环境条件下, 溶解态金属浓度还受其他自然或人为因素影响, 如NH₄-N, NO₃-N, 悬浮物(SS)和水温等。水质和风险评价结果表明, 长江源区水质极好, 流域西部高海拔地区存在不同程度的沉积物Zn, Pb和Cd污染, 与该区域附近的铅锌矿床有关。Cd是构成长江源沉积物潜在生态风险的主要因素。研究结果能够弥补长江源实测数据缺乏的不足, 为长江源乃至整个长江流域的重金属污染防控提供理论依据。