海螺沟冰川融水径流中汞与悬浮颗粒物的季节变化特征及其关系研究

为研究冰川融水径流中汞与悬浮颗粒物的变化及其相关关系，于2019年6月～2020年9月在青藏高原东南缘海螺沟冰川融水径流进行为期一年的连续定点采样，测试了样品中汞形态含量和悬浮颗粒物的数量、含量及粒径特征。分析表明，总汞的平均含量为6.96～10.78 ng/L，其中颗粒态汞为4.54～9.14 ng/L，溶解态汞为1.53～2.42 ng/L，与青藏高原及世界其他偏远地区河流汞含量相当。各形态汞与悬浮颗粒物不同特征在不同季节的相关关系差异显著，总汞和颗粒态汞含量与总悬浮颗粒物含量和数量在夏季消融盛期具有突出且一致的正相关关系，但在秋冬季并未显示出正相关，表明前人揭示的冰川补给河流中颗粒物控制汞含量变化的结论具有季节局限性。冰川径流中的汞受水文过程和汞的来源及其在水体中的转化等多因素影响，汞形态含量与悬浮颗粒物不同物理特征在不同季节的差异性可能反映了不同季节汞的来源和传输机制的差异。

Seasonal Variation and Relationship between Mercury and Suspended Particulate Matter in Hailuogou Glacier Meltwater Runoff

To investigate the relationship between mercury and suspended particle in glacial meltwater runoff, a consecutive series water samples were collected at a fixed-point from Hailuogou glacier meltwater runoff in the southeastern margin of the Tibetan Plateau from June 2019 to September 2020. Mercury speciation and the quantity, content and size of suspended particles (SP) were measured. The results showed that the average concentration of total mercury, particulate mercury and dissolved mercury ranged 6.96-10.78 ng/L, 4.54-9.14 ng/L and 1.53-2.42 ng/L, respectively, which is comparable to that of rivers in the Tibetan Plateau and other remote areas in the world. Correlations between mercury and the characteristics of SP in different seasons are significantly different. The content of total mercury and particulate mercury was positively correlated with the content and quantity of SP during the summer. However, there was no positive correlation in autumn and winter, indicating that previous conclusion of mercury dominated by SP in glacier-fed rivers is likely exclusively applicable at summer ablation season. We suggested that mercury in glacial runoff is conjointly affected by hydrological processes, mercury''s sources and its transformation in river water. The differences of correlations between mercury speciation and physical characteristics of SP in different seasons may suggest distinct sources and transport mechanisms of mercury in different seasons.