Abstract
A simple, catchment-scale, cascade model was used toassess the importance of sinks and sources ofmethylmercury (MeHg) in a boreal catchment thatcontains a forested upland, a lowland peatland and asmall lake. The three compartment model was run usingrealistic flow rates and atmospheric loading of MeHg,and the model was constrained by observedconcentrations of MeHg in each compartment. Assumingno internal sinks and sources of MeHg, modelledcatchment yields showed reasonable agreement withfield observation, but the predicted internal MeHgconcentrations in each compartment were implausible. Only when sources and sinks of MeHg are added to thethree compartments do MeHg-pool concentrations fallinto the range of those measured in the field. Tomaintain both catchment-scale and compartment-scalecontinuity, the upland and peatland were net sourcesof MeHg (0.0007 and 0.1065 mg ha-1 d-1respectively), and the lake a net sink (-0.2215 mgha-1 d-1). These source/sink rates are 1.73,259 and -539 times the input of MeHg via wetprecipitation input for the modelled ice-free season. Sensitivity analysis revealed that the volume ofrunoff delivered to the peatland by the upland area,peatland size and porewater MeHg concentration in thepeatland are important controls on catchment MeHgyield, and that contemporary atmospheric deposition ofMeHg is insignificant compared to the sources of MeHgwithin the catchment.
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References
Branfireun BA, Heyes A & Roulet NT (1996) The hydrology and methylmercury dynamics of a Precambrian Shield headwater peatland. Water Resources Research 32(6): 1785–1974
Branfireun BA & Roulet NT (1997) The baseflow and stormflow hydrology of a Precambrian Shield headwater peatland. Hydrological Processes, in press
Bishop K, Lee Y-H, Petterson C & Allard B (1995) Methylmercury in runoff from the Svartberget catchment in northern Sweden during a stormflow episode. Water, Air and Soil Pollution 80: 221–224
Bishop K, Lee Y-H, Petterson C & Allard B (1995) Terrestrial sources of methylmercury in surface waters: The importance of the riparian zone on the Svartberget Catchment. Water, Air and Soil Pollution 80: 435–444
Charles-Edwards DA (1982) Physiological Determinants of Crop Growth. Academic Press, Sydney. 161 pp
Hultberg H, Munthe J & Iverfeldt Å (1995) Cycling of methyl mercury and mercury-responses in the forest roof catchment to three years of decreased atmospheric deposition. Water, Air and Soil Pollution 80: 415–424
Hurley JP, Benoit JM, Babiarz, CL Shafer MM, Andren AW, Sullivan JR, Hammond R & Webb DA (1995) Influences of watershed characteristics on mercury levels in Wisconsin rivers. Environmental Science and Technology 29(7): 1867–1875
Krabbenhoft DP, Benoit JM, Babiarz CL, Hurley JP & Andren AW (1995) Mercury cycling in the Allequash Creek watershed, northern Wisconsin. Water, Air and Soil Pollution 80: 425–433
Moore TR, Bubier JL, Heyes A & Flett RJ (1995) Methyl and total mercury in boreal wetland plants, Experimental Lakes Area, northwestern Ontario. Journal of Environmental Quality 24: 845–850
Oke TR (1987) Boundary Layer Climates (2nd ed.). Methuen, London. 435 pp
Roulet NT, Munron S & Mortsch L (in press) Wetlands. In: Bayley W, Oke T & Rouse W (Eds) Surface Climate of Canada. Queens University Press, McGill.
Sellers P, Rudd JWM, Kelly CA & Machutcheon A (1996) Photodegradation of methylmercury in lakes. Nature 380: 694–697
St. Louis VL, Rudd JWM, Kelly CA, Beaty KG, Bloom NS & Flett RJ (1994) Importance of wetlands as sources of methyl mercury to boreal forest ecosystems. Canadian Journal of Fisheries and Aquatic Sciences 51: 1065–1076
St. Louis VL, Rudd JWM, Kelly CA & Barrie LA (1995) Wet deposition ofmethyl mercury in northwestern Ontario compared to other geographic locations. Water, Air and Soil Pollution 80: 405–414
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Branfireun, B.a., Hilbert, D. & Roulet, N. Sinks and sources of methylmercury in a boreal catchment. Biogeochemistry 41, 277–291 (1998). https://doi.org/10.1023/A:1005964603828
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DOI: https://doi.org/10.1023/A:1005964603828