Postimpoundment time course of increased mercury concentrations in fish in hydroelectric reservoirs of northern Manitoba, Canada
Postimpoundment time course of increased mercury concentrations in fish in hydroelectric reservoirs of northern Manitoba, Canada
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DOI：
10.1007/s00244-006-0113-4
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发表时间：
2007-10-01
影响因子：
4
通讯作者：
Green, D. J.
中科院分区：
文献类型：
--
作者：
Bodaly, R. A. (Drew);Jansen, W. A.;Green, D. J.
北方水库中鱼类的汞（Hg）浓度已被证明在蓄水后长达30年的时间内会增加。然而，浓度增加的时间过程尚不清楚。本研究的目的是确定汞浓度的演变在北方水库的北方马尼托巴，加拿大，其与洪水的严重程度。我们确定了总汞浓度在三种鱼类长达35年的蓄水后，在14个湖泊和湖盆。沉积后的趋势取决于鱼类和水库。在底栖性湖白鲑（Coregonus clupeaformis）中，汞浓度在洪水后增加到0.2至0.4 μ g g（-1）湿重，而蓄水前的浓度为0.06至0.14 μ g（-1），天然湖泊中的浓度为0.03至0.06 μ g（-1）。湖泊白鲑体内的汞浓度通常在湖泊蓄水后6年内最高，蓄水后10至20年才降至背景浓度。洪水后2至8年，捕食性北方梭子鱼（Esox lucius）和海象（Sander vitreus）体内的汞浓度最高，为0.7至2.6 μ g g（-1），而蓄水前的浓度为0.19至0.47 μ g（-1），天然湖泊中的浓度为0.35至0.47 μ g（-1）。这些掠食性物种体内的汞浓度在随后几年持续下降，需要10至23年才能恢复到背景水平。因此，结果表明营养水平对汞浓度的影响（生物放大作用）。汞的峰值浓度取决于洪水量（湖面面积的相对增加）。在大约100%的洪水条件下，湖白鲑的渐近浓度大约为0.25 μ g g（-1），海象和北方狗鱼的渐近浓度大约为1.6 μ g（-1）。下游影响是明显的，因为其他蓄水池下游的许多水库鱼体内的汞浓度高于根据洪水量预期的浓度。
Mercury (Hg) concentrations in fish in boreal reservoirs have been shown to be increased for up to 3 decades after impoundment. However, the time course of increased concentrations is not well known. The purpose of this study was to determine the evolution of Hg concentrations in fish in the boreal reservoirs of northern Manitoba, Canada, and its relationship with severity of flooding. We determined total Hg concentrations in three species of fish for up to 35 years after impoundment in 14 lakes and lake basins. Postimpoundment trends depended on fish species and reservoir. In the benthivorous lake whitefish (Coregonus clupeaformis), Hg concentrations increased after flooding to between 0.2 and 0.4 mu g g(-1) wet weight compared with preimpoundment concentrations between 0.06 and 0.14 mu g g(-1) and concentrations in natural lakes between 0.03 and 0.06 mu g g(-1). Hg concentrations in lake whitefish were usually highest within 6 years after lake impoundment and took 10 to 20 years after impoundment to decrease to background concentrations in most reservoirs. Hg concentrations in predatory northern pike (Esox lucius) and walleye (Sander vitreus) were highest 2 to 8 years after flooding at 0.7 to 2.6 mu g g(-1) compared with preimpoundment concentrations of 0.19 to 0.47 mu g g(-1) and concentrations in natural lakes of 0.35 to 0.47 mu g g(-1). Hg concentrations in these predatory species decreased consistently in subsequent years and required 10 to 23 years to return to background levels. Thus, results demonstrate the effect of trophic level on Hg concentrations (biomagnification). Peak Hg concentrations depended on the amount of flooding (relative increase in lake surface area). Asymptotic concentrations of approximately 0.25 mu g g(-1) for lake whitefish and 1.6 mu g g(-1) for both walleye and northern pike were reached at approximately 100% flooding. Downstream effects were apparent because many reservoirs downstream of other impoundments had higher Hg concentrations in fish than would be expected on the basis of flooding amount.