Lakes Sediment Watersheds

Benoit, J. M., Fitzgerald, W. F. Damman, A. W. H. 1998. The biogeochemistry of an ombrotrophic bog Evaluation of use as an archive of atmospheric mercury deposition. Environmental Research, 78, 118-133. Engstrom, D.R. Swain, E.B. 1997. Recent declines in atmospheric mercury deposition in the upper Midwest. Environmental Science and Technology, 31, 960-967. Engstrom, D.R., Swain, E.B., Henning, T.A., Brigham, M.E. Brezonik, P.L. 1994. Atmospheric Mercury Deposition to Lakes and Watersheds - a Quantitative Reconstruction from Multiple Sediment Cores. In Environmental Chemistry of Lakes and Reservoirs. 33-66. 

Hg flux and watershed area, the relative importance of direct deposition and catchment contributions can be assessed. Such interpretations assume that lake sediments are stratigraphically and quantitatively reliable archives of Hg inputs to aquatic systems. 

Munawar, M., Munawar, I.F., Burley, M., Carou, S. and Niblock, H. (2003) Multi-trophic bioassessment of stressed "Areas of Concern" of the Lake Erie watershed, in M. Munawar (ed.), Sediment Quality Assessment and Management Insight and Progress, Aquatic Ecosystem Health and Management... 

Atmospheric-home mercury, including anthropogenic mercury is deposited everywhere including remote areas of the globe, hundreds of kilometers from the nearest mercury source, as evidenced by its presence in ancient lake sediments and glacial ice. In Amituk Lake in the Canadian Arctic, recent annual deposition of mercury was estimated at 15.1kg, about 56% from snowpack, and the rest from precipitation. This represents a dramatic increase from historic annual burdens of 6.0 kg of mercury aimually in this remote area the effects of this increase on Arctic watersheds are unknown. 

Engstrom, D. R., E. B. Swain, T. A. Henning, M. E. Brigham P. L. Brezonik, 1994. Atmospheric mercury deposition to lakes and watersheds — a quantitative reconstruction from multiple sediment cores. Advances in Chemistry Series 237 33-66. 

Mathewes, R. W. J. M. D Auria, 1982. Historic changes in an urban watershed determined by pollen and geochemical analyses of lake sediment. Can J. Earth Sci. 19 2114-2125. 

Freshwater lakes often have well-defined catchments (or watersheds) and receive sediment from many sources, most of which have unique or well-defined magnetic characteristics (which must also be measured as part of a comprehensive magnetic study of lake-sediments). The majority of magnetic minerals found in lake-sediments are derived by catchment erosion and originate from bedrock, subsoil, and topsoil in the lake s drainage... 

Rawn, D. F. K., W. L. Lockhart, P. Wilkinson, D. A. Savoie D. C. G. Muir, 2001. Historical Contamination ofYukon Lake Sediments by PCBs and Organochlorine Pesticides Influence of Local Sources and Watershed Characteristics. Sci. Total Environ. 280 17-37. 

No information is available on volatilization of mercury from either the lake or watershed. There is also no estimate of exchange between lake water and sediment. Vfork is in progress to evaluate these fluxes. Since Cranberry Lake s seasonal thermo-cline is quite deep (lOm), most of its bottom waters are rarely anoxic. (LaRow, unpublished data). Thus, considerable methyla-tion of mercury should be occurring in the bottom sediments. 

Between 1890 and 1902, the sedimentation rate identified as Region II of figure 3 averaged 1800 g m"2 yr-1 or 0.83 cm yr-1, i.e., greater than 10 times the pre-cultural rate. Historical records and photographs show that by 1895 most of the land comprising the watershed had been logged and the suburbs of Seattle had reached the lake shore. This rapid land development in the watershed occurred about the turn of the century. 

Sorensen, J.A., G.E. Glass, K.W. Schmidt, J.K. Huber, and G.R. Rapp, Jr. 1990. Airborne mercury deposition and watershed characteristics in relation to mercury concentrations in water, sediments, plankton, and fish of eighty northern Minnesota lakes. Environ. Sci. Technol. 24 1716-1727. 

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