title: Parsimonious Model for Simulating Total Mercury and Methylmercury in Boreal Streams Based on Riparian Flow Paths and Seasonality.
abstract: 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.
authors.affiliation: †Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-75007 Uppsala, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Eklöf
authors.affiliation: †Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-75007 Uppsala, Sweden.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kraus
authors.affiliation: †Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-75007 Uppsala, Sweden.
authors.forename: Martyn
authors.initials: M
authors.lastname: Futter
authors.affiliation: §Department of Limnology and Bio-oceanography, University of Vienna, A-1090 Vienna, Austria.|∥Department of Forest Ecology and Management, Swedish University of Agricultural Science, SE-90183 Umeå, Sweden.
authors.forename: Jakob
authors.initials: J
authors.lastname: Schelker
authors.affiliation: ⊥Department of Applied Environmental Science, Stockholm University, SE-10691 Stockholm, Sweden.
authors.forename: Markus
authors.initials: M
authors.lastname: Meili
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Boyer
authors.affiliation: †Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-75007 Uppsala, Sweden.|#Department of Earth Sciences, Uppsala University, SE-75236 Uppsala, Sweden.
authors.forename: Kevin
authors.initials: K
authors.lastname: Bishop
mesh_terms: D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D008962:Models, Theoretical; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D012987:Soil / Q000737:chemistry; D013548:Sweden; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D008767:Methylmercury Compounds; D012987:Soil; D014874:Water Pollutants, Chemical; D008628:Mercury