U.S. Geological Survey, 3215 Marine Street, Boulder, Colorado 80303, United States.
Environ Sci Technol. 2011 Nov 1;45(21):9262-7. doi: 10.1021/es202068b. Epub 2011 Oct 6.
We measured mercury (Hg) concentrations and calculated export and yield from the Yukon River Basin (YRB) to quantify Hg flux from a large, permafrost-dominated, high-latitude watershed. Exports of Hg averaged 4400 kg Hg yr(-1). The average annual yield for the YRB during the study period was 5.17 μg m(-2) yr(-1), which is 3-32 times more than Hg yields reported for 8 other major northern hemisphere river basins. The vast majority (90%) of Hg export is associated with particulates. Half of the annual export of Hg occurred during the spring with about 80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic effects to biota. Dissolved and particulate organic carbon exports explained 81% and 50%, respectively, of the variance in Hg exports, and both were significantly (p < 0.001) correlated with water discharge. Recent measurements indicate that permafrost contains a substantial reservoir of Hg. Consequently, climate warming will likely accelerate the mobilization of Hg from thawing permafrost increasing the export of organic carbon associated Hg and thus potentially exacerbating the production of bioavailable methylmercury from permafrost-dominated northern river basins.
我们测量了汞（Hg）浓度，并计算了育空河流域（YRB）的输出量和产量，以量化从一个大型、以永久冻土为主、高纬度流域的汞通量。Hg 的平均出口量为 4400 千克 Hg yr(-1)。在研究期间，YRB 的年平均产量为 5.17 μg m(-2) yr(-1)，是其他 8 个主要北半球河流流域 Hg 产量的 3-32 倍。Hg 出口的绝大部分（90%）与颗粒物质有关。每年有一半的 Hg 出口发生在春季，约 80%的 34 个样本超过了美国环保署规定的生物慢性不利影响 Hg 标准。溶解态和颗粒态有机碳的输出分别解释了 Hg 输出的 81%和 50%，两者与水排放量均呈显著正相关（p < 0.001）。最近的测量表明，永久冻土中含有大量的 Hg 储备。因此，气候变暖可能会加速解冻永久冻土中 Hg 的释放，增加与有机碳相关的 Hg 输出，从而可能加剧主要由永久冻土控制的北方河流流域中生物可利用的甲基汞的产生。
