Ecosystems Research Group, Ltd., PO Box 1227, Norwich, VT 05055, USA.
Ecotoxicology. 2012 Apr;21(3):705-18. doi: 10.1007/s10646-011-0829-4. Epub 2011 Dec 23.
Lake Champlain continues to experience mercury contamination resulting in public advisories to limit human consumption of top trophic level fish such as walleye. Prior research suggested that mercury levels in biota could be modified by differences in ecosystem productivity as well as mercury loadings. We investigated relationships between mercury in different trophic levels in Lake Champlain. We measured inorganic and methyl mercury in water, seston, and two size fractions of zooplankton from 13 sites representing a range of nutrient loading conditions and productivity. Biomass varied significantly across lake segments in all measured ecosystem compartments in response to significant differences in nutrient levels. Local environmental factors such as alkalinity influenced the partitioning of mercury between water and seston. Mercury incorporation into biota was influenced by the biomass and mercury content of different ecosystem strata. Pelagic fish tissue mercury was a function of fish length and the size of the mercury pool associated with large zooplankton. We used these observations to parameterize a model of mercury transfers in the Lake Champlain food web that accounts for ecosystem productivity effects. Simulations using the mercury trophic transfer model suggest that reductions of 25-75% in summertime dissolved eplimnetic total mercury will likely allow fish tissue mercury concentrations to drop to the target level of 0.3 μg g(-1) in a 40-cm fish in all lake segments. Changes in nutrient loading and ecosystem productivity in eutrophic segments may delay any response to reduced dissolved mercury and may result in increases in fish tissue mercury.
尚普兰湖继续受到汞污染的影响，这导致发布了公共建议，限制人类食用顶级营养级鱼类，如大眼梭鲈。先前的研究表明，生物体内的汞含量可以通过生态系统生产力的差异以及汞负荷的差异来改变。我们研究了尚普兰湖中不同营养级别的汞之间的关系。我们测量了来自 13 个代表不同营养负荷条件和生产力范围的地点的水、悬浮物和两种浮游动物大小级别的无机汞和甲基汞。在所有测量的生态系统隔室中，生物量在不同的湖泊段中差异显著，这是由于营养水平的显著差异所致。局部环境因素，如碱度，影响了汞在水和悬浮物之间的分配。生物量和不同生态层的汞含量影响了生物体内汞的纳入。浮游鱼类组织中的汞是鱼类长度和与大型浮游动物相关的汞库大小的函数。我们利用这些观察结果来参数化尚普兰湖食物网中汞转移的模型，该模型考虑了生态系统生产力的影响。使用汞营养级转移模型进行的模拟表明，在所有湖泊段中，夏季溶解表水总汞减少 25-75%，可能会使 40 厘米长的鱼的组织汞浓度降至 0.3μg/g 的目标水平。富营养段中营养负荷和生态系统生产力的变化可能会延迟对溶解汞减少的任何反应，并可能导致鱼类组织中汞含量增加。
