Environmental Biogeochemistry of Mercury

Mercury occupies a unique and infamous place in environmental biogeocbemistry. It was tbe first chemical species for which a direct connection was proven between relatively low concentrations in a natural water system, bioaccumulation up the biogeochemical food webs, and a serious health impact on the human population at the top of the food chain. 

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The major complicating factor in environmental biogeochemistry of mercury and its speciation is the biological methylation of Hg " " to CHjHg" and (CH3)2Hg. This process converts inorganic mercury to organo-mercury, which is both more lipophilic and toxic (see below). 

As a point of analytical and environmental interest, Hg is more readily measured in natural waters than MMHg. Since the in situ production of MMHg and Hg° is proportional to the supply of reactive mercury, a comprehensive understanding of the aqueous Hg° cycle and its temporal and spatial patterns may provide a means to constrain and improve predictive models for the aquatic and atmospheric biogeochemistry of mercury and MMHg in natural waters. For a sense of the potential geochemical benefits from automated Hg° measurements, the reader is referred to some recent field studies of Hg° (e.g., Lindberg et al., 2000 Amyot et al., 2001 Balcom et al., 2000). 

The way forward will be a fascinating and challenging one. As we have summarized, this is because the biogeochemistry of mercury operates at a variety of time and space scales and in many environmental media. Due to the complexity of the processes and the minute quantities of material often encountered in the environment, future research will also require new hypotheses and new instrumentation. Similarly, and as with so many environmental research elforts, new collaborations among scientific disciplines will be required. 

Mercury and lead serve no known biological function, but both are useful metals and employed by mankind since ancient times. Both are also toxic environmental contaminants and thus of prime concern for several governmental agencies. AU this has led to intense research on the biogeochemistry of mercury and lead, including their speciation in the environment, their atmospheric transport, and the processes affecting their fate these topics and more are summarized in Chapters 9 and 10. 

Colwell, R.R., G.S. Sayler, J.D. Nelson, Jr., and A. Justice. 1976. Microbial mobilization of mercury in the aquatic environment. Pages 437-487 in J. 0. Nriagu (ed.). Environmental Biogeochemistry, Vol. 2. Metals Transfer and Ecological Mass Balances. Ann Arbor Sci. Publ., Ann Arbor, MI. 

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. 

Discuss the behavior of mercury in the modem environment. Why is this metal of special attention for environmental biogeochemistry ... 

Hintelman H and Ogrinc N (2003) Determination of stable mercury isotopes by ICP/MS and their application in environmental studies. In Cai Yand Braids OC, eds. Biogeochemistry of Environmentally Important Trace Elements, pp. 321-338. American Chemical Society. 

Peter J. Dillon, Ph.D. (Toronto), F.R.S.C. is a Professor in the Environmental Resource Studies and Chemistry Departments at Trent University where he is Director of the new Water Quality Center. His research interests focus on biogeochemistry effects of regional and global-scale stressors including acid deposition, climate change, mercury and other trace metals on environmental chemistry. 

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