†Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-75007 Uppsala, Sweden.
§Department of Limnology and Bio-oceanography, University of Vienna, A-1090 Vienna, Austria.
Environ Sci Technol. 2015 Jul 7;49(13):7851-9. doi: 10.1021/acs.est.5b00852. Epub 2015 Jun 25.
The complexity of mercury (Hg) biogeochemistry has made it difficult to model surface water concentrations of both total Hg (THg) and especially methylmercury (MeHg), the species of Hg having the highest potential for bioaccumulation. To simulate THg and MeHg variation in low-order streams, we have adapted a conceptual modeling framework where a continuum of lateral flows through riparian soils determines streamflow concentrations. The model was applied to seven forest catchments located in two boreal regions in Sweden spanning a range of climatic, soil, and forest management conditions. Discharge, and simulated riparian soil water concentrations profiles, represented by two calibrated parameters, were able to explain much of the variability of THg and MeHg concentrations in the streams issuing from the catchments (Nash Sutcliffe (NS) up to 0.54 for THg and 0.58 for MeHg). Model performance for all catchments was improved (NS up to 0.76 for THg and 0.85 for MeHg) by adding two to four parameters to represent seasonality in riparian soil water THg and MeHg concentrations profiles. These results are consistent with the hypothesis that riparian flow-pathways and seasonality in riparian soil concentrations are the major controls on temporal variation of THg and MeHg concentrations in low-order streams.
汞（Hg）生物地球化学的复杂性使得同时模拟地表水中总汞（THg）和特别是甲基汞（MeHg）的浓度变得困难，而甲基汞是最具生物累积潜力的汞形态。为了模拟低阶溪流中 THg 和 MeHg 的变化，我们采用了一种概念建模框架，其中通过河岸土壤的连续侧向流动来确定溪流浓度。该模型应用于瑞典两个北方地区的七个森林流域，涵盖了一系列气候、土壤和森林管理条件。排放和模拟的河岸土壤水浓度剖面，由两个校准参数表示，能够解释很大一部分源自这些流域的溪流中 THg 和 MeHg 浓度的变异性（THg 的纳什-苏特克里夫（NS）可达 0.54，MeHg 可达 0.58）。通过添加两个到四个参数来表示河岸土壤水中 THg 和 MeHg 浓度剖面的季节性，所有流域的模型性能都得到了改善（THg 的 NS 可达 0.76，MeHg 的 NS 可达 0.85）。这些结果与假设一致，即河岸流径和河岸土壤浓度的季节性是控制低阶溪流中 THg 和 MeHg 浓度时间变化的主要因素。
