• 关键词：汞  时空特征  梯级水库  筑坝拦截  澜沧江

• 基金项目：江苏省自然科学基金青年项目（ No.BK20200158）；中国博士后基金面上项目（ No.2019M661882）

• 马宏海
• 南京水利科学研究院生态环境研究中心，南京 210029;四川大学水利水电学院，成都 610065

• 陈求稳
• 南京水利科学研究院生态环境研究中心，南京 210029

• 刘东升
• 南京水利科学研究院生态环境研究中心，南京 210029

• 陈宇琛
• 南京水利科学研究院生态环境研究中心，南京 210029;南京大学环境学院，南京 210029

• 摘要：拦河筑坝对河流中汞的输运产生重要影响，但有关高海拔落差河流中汞的来源及输运特征的认识较为匮乏.以澜沧江为研究对象，监测了筑坝河段水体中汞浓度的年时空变化过程（2017—2018），量化了梯级水库对汞沿程输运的影响.结果表明，澜沧江水体中汞浓度总体与径流的季节分配呈同步变化趋势，但在上下游因土地利用类型的差异而呈现相反的季节性变化特征.因水库的拦截，溶解态汞与总汞的比值沿程呈上升趋势，加之水库泄水量的沿程增加，共同导致了河流汞通量自上游至下游呈非连续累积的趋势，从144 kg·a^-1增加至788 kg·a^-1.相应地，梯级水库对汞的拦截率自上游至下游由88%逐渐降低至65%.该项研究丰富了对梯级水库中汞的补给和输运的认识.

• Abstract：Damming can significantly impact riverine mercury （Hg） transport. However， knowledge on the source and transport of Hg in rivers of high altitude drop is lacking. Temporal and spatial variations of Hg concentration along the Lancang River were monitored from July 2017 to June 2018. Results showed that Hg concentration in Lancang River showed a similar trend with annual runoff distribution； however， contrasting seasonal changes between upstream and downstream reservoirs were observed mainly due to different land uses and runoff recharge along the flow direction. The increasing trend of DHg/THg （ratio of particulate Hg to total Hg） and reservoir discharge caused the Hg flux to increase from 144 kg·a^-1 to 788 kg·a^-1 when focusing on changes along cascade reservoirs. Correspondingly， the Hg interception rate of cascade reservoirs from upstream to downstream gradually decreases from 88% to 65%. The results of this study provide new insights into the source and transport of Hg in cascade dams.

• Key words：mercury  temporal and spatial characteristics  cascade reservoirs  reservoir interception  Lancang River

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