Stoor Richard W, Hurley James P, Babiarz Christopher L, Armstrong David E
University of Wisconsin-Madison, Environmental Chemistry and Technology Program, Madison, WI 53706-1481, USA.
Sci Total Environ. 2006 Sep 1;368(1):99-110. doi: 10.1016/j.scitotenv.2005.10.019. Epub 2005 Dec 7.
Identification of sites of methyl mercury (MeHg) production is critical to predicting long-term fate of bioaccumulative Hg in the aquatic environment. During baseflow, when groundwater sources dominate, we observed consistently elevated levels of MeHg (0.1-0.4 ng L(-1)) at the mouth and in several tributaries to the Tahquamenon River in the Lake Superior watershed. MeHg concentrations in groundwater observation wells exceeded 0.6 ng L(-1) in a coniferous catchment with highly conductive sandy surficial deposits. Furthermore, we identified MeHg concentrations as high as 12 ng L(-1) in the hyporheic zone of East Creek, a tributary to the Tahquamenon. This study confirms the importance of groundwater as a source of MeHg in watersheds of the Great Lakes. Indirect groundwater discharge represents a major component of flow in rivers of the basin, further emphasizing the need to better understand subsurface MeHg production and transport processes when modeling watershed responses and biogeochemical fate of Hg in the Great Lakes.
确定甲基汞（MeHg）的产生地点对于预测水生环境中生物累积性汞的长期归宿至关重要。在基流期间，当地下水源占主导时，我们在苏必利尔湖流域塔夸门农河河口及其几条支流中持续观测到甲基汞水平升高（0.1 - 0.4纳克/升）。在一个具有高导电性砂质表层沉积物的针叶林集水区，地下水观测井中的甲基汞浓度超过了0.6纳克/升。此外，我们在塔夸门农河的一条支流东溪的潜流带中发现甲基汞浓度高达12纳克/升。这项研究证实了地下水作为大湖流域甲基汞来源的重要性。间接地下水排放是该流域河流流量的一个主要组成部分，这进一步强调了在模拟大湖流域汞的生物地球化学归宿以及流域响应时，需要更好地了解地下甲基汞的产生和传输过程。
