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首页> 外文期刊>Lakes & Reservoirs >Watershed influences on the transport, fate and bioavailability of mercury in Lake Superior: Field measurements and modelling approaches
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Watershed influences on the transport, fate and bioavailability of mercury in Lake Superior: Field measurements and modelling approaches

机译：分水岭对苏必利尔湖中汞的迁移，命运和生物利用度的影响：现场测量和建模方法

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The issuance of fish consumption advisories in US states bordering Lake Superior has heightened the need for understanding the biogeochemical cycling and transformations of mercury in this great lake. Major routes of mercury (Hg) transport to lakes include atmospheric deposition (wet and dry), direct discharges and riverine (watershed) inputs. The specific objectives of this ongoing study are to: (ⅰ) determine the speciation and bioavailability of Hg transported to Lake Superior (ⅱ) determine the importance of watershed-specific characteristics that control physical and chemical forms of Hg; (ⅲ) identify key mechanisms controlling Hg bioavailability and speciation in near-shore zones relative to open lake regions; and (ⅳ) provide process-level information to compliment concurrent development of Hg fate and transport models of the Lake Superior ecosystem. Three tributaries of Lake Superior were chosen for detailed field study based on previous results and particular watershed characteristics. Mixing zones represent a potentially important zone of Hg entry into the food chain, and were sampled for biota, water and sediment in transects between the tributary mouth and the lake end member. Sampling of open-water sites was conducted during Environmental Protection Agency-sponsored cruises on the research vessel Lake Guardian. Results from our work on Lake Superior tributaries demonstrate that dissolved organic carbon and methylmercury (MeHg) export was greatest from watersheds containing wetlands. In Lake Superior, concentrations of Hg species were small at pelagic stations (total mercury (HgT) averaged 0.49 ng/L, MeHg averaged 6.4 pg/L). In contrast, MeHg concentrations in tributaries ranged from 100 to 250 pg/L. Watershed sites dominated by wetlands exhibited the greatest MeHg concentrations, occasionally in excess of 12 ng/L. Samples of bulk zooplankton ranged from 20 to 130 ng/g dry weight HgT and from 15 to 45 ng/g dry weight MeHg, and demonstrated typical bioacculmulation of mercury as well as distinct seasonality in concentrations.
机译：在与苏必利尔湖接壤的美国各州发布的鱼类消费咨询意见，使人们更加需要了解这个大湖中汞的生物地球化学循环和汞转化。汞向湖泊的主要运输途径包括大气沉积（干湿），直接排放和河流（分水岭）输入。这项正在进行的研究的具体目标是：（ⅰ）确定运往苏必利尔湖的汞的形态和生物利用度。（ⅱ）确定控制汞的物理和化学形式的分水岭特性的重要性； （ⅲ）确定相对于开放湖区控制近岸区域汞生物利用度和形态的关键机制； （ⅳ）提供过程级信息，以补充同时发生的苏必利尔湖生态系统的汞命运和运输模型。根据先前的结果和特定的分水岭特征，选择了苏必利尔湖的三个支流进行了详细的实地研究。混合区是汞进入食物链的一个潜在重要区域，并在支流口和湖末段之间的样带中对生物，水和沉积物进行了采样。在环境保护署赞助的研究船“瓜迪安湖”号航行期间，对露天水域进行了采样。我们对苏必利尔湖支流的研究结果表明，含有湿地的流域的溶解有机碳和甲基汞（MeHg）出口量最大。在苏必利尔湖，远洋站的汞物种浓度很小（总汞（HgT）平均为0.49 ng / L，MeHg平均为6.4 pg / L）。相反，支流中的MeHg浓度范围为100至250 pg / L。以湿地为主的集水区的MeHg浓度最高，偶尔超过12 ng / L。浮游动物的浮游生物样本的干重HgT为20至130 ng / g，甲基汞的干重为15至45 ng / g，证明了汞的典型生物富集性以及浓度的明显季节性。

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