作者：Li, M., Li, D., Sun, X., Hawkings, J., Sonke, J., Zhang, Y. & Zhang, Q.

Glacier-fed streams (GFSs) export large amounts of suspended sediment (SS) and associated mercury, with important implications for downstream water quality, yet the controls on Hg export remain poorly constrained. This issue is particularly acute on the Tibetan Plateau, where glacier meltwater sustains major Asian rivers. Here, we quantify seasonal and diurnal variability (n = 350) in SS and Hg across six Tibetan Plateau GFSs and synthesize observations from 36 GFSs worldwide. Tibetan Plateau GFSs exhibit total Hg (THg) concentrations and yields comparable to Alaska, but higher than most GFSs with similar glacier coverage. In GFSs without proglacial lakes, THg export scales with SS and increases with glacier coverage and velocity, indicating mobilization of erosion-derived, particle-associated Hg. THg-SS hysteresis differs among glacier thermal regimes in response to particle sorting and subglacial drainage evolution. Our results suggest that intensifying melt and rainfall on the Tibetan Plateau may increase Hg yields and delay the timing of peak Hg export, whereas expanding proglacial lakes may temporarily buffer further downstream Hg export. This study identifies controls on SS and THg export in Tibetan Plateau GFSs and highlights implications for downstream water quality and ecosystem exposure under glacier retreat.

冰川补给河流（GFSs）向下游输送大量悬浮泥沙（SS）及其吸附的汞，对下游水质具有重要意义，然而控制汞输出的机制仍不明确。这一问题在青藏高原尤为突出——那里的冰川融水维系着亚洲多条大河。研究量化了青藏高原6条冰川补给河流中悬浮泥沙与汞的季节及日尺度变化（n = 350），并综合了全球36条冰川补给河流的观测数据。结果表明，青藏高原冰川补给河流的总汞（THg）浓度与输出产率与阿拉斯加相当，但高于冰川覆盖率相近的大多数冰川补给河流。在没有冰前湖（proglacial lakes）的冰川补给河流中，THg输出量随SS量级缩放，并随冰川覆盖率和流速的增大而升高，表明其以侵蚀来源、颗粒吸附态汞的活化为主。THg—SS滞回关系因冰川热力状态（thermal regime）不同而存在差异，其对泥沙颗粒分选与冰下排水系统演化的响应各异。研究结果表明，青藏高原融冰与降雨的增强可能提高汞输出产率并使汞输出峰值时间延后；而冰前湖的扩张则可能暂时缓冲向下游的汞输出。本研究识别了青藏高原冰川补给河流SS与THg输出的控制因素，并揭示了冰川退缩背景下其对下游水质与生态系统暴露风险的意义。

（来源：Environmental Science & Technology 2026Issue 19  DOI: 10.1021/acs.est.6c01369）