Atmospheric mercury pollution due to losses of terrestrial carbon pools?
Plants accumulate significant amounts of atmospheric mercury (Hg) in aboveground biomass, likely sequestering over 1,000 Mg of atmospheric Hg every year. This large mercury uptake could be strong enough to affect tropospheric Hg levels and might be partially responsible for seasonal variations in atmospheric Hg observed at Mace Head, Ireland. The fluctuations of Hg concentrations coincide temporally with the annual oscillation of carbon dioxide (CO2) in the Northern Hemisphere, which is a result of seasonal growth of vegetation. Therefore, declining Hg concentrations in spring and summer may be attributed in part to plant uptake of atmospheric Hg. Further, the increase of Hg concentrations during non-active vegetation periods might partially be due to plant-derived Hg emitting back to the atmosphere during carbon mineralization. The implications of these propositions are that past and future changes in biomass productivity and organic carbon pools may have had—and may continue to have—significant effects on atmospheric Hg levels. Specifically, large losses in soil and biomass carbon pools in the last 150 years could have contributed significantly to observed increases in atmospheric Hg pollution. The roles of vegetation and terrestrial carbon pools should receive detailed consideration on how they might attenuate or exacerbate atmospheric Hg pollution.
KeywordsAtmospheric mercury Plant mercury uptake Carbon mineralization Mercury sequestration Seasonality
I would like to thank Jay Arnone, Harald Biester, Christophe Ferrari, Dale Johnson, Hans Moosmüller, and two anonymous reviewers for valuable inputs and editorial comments to this manuscript. This research was in part supported by the National Science Foundation (ATM 0632780) and by the Desert Research Institute.
- Fritsche J, Obrist D, Alewell C (2006) Effects of microbiological activity on Hg0 emission in uncontaminated terrestrial soils. In: Abstracts of the 8th international conference on mercury as a global pollutant, Madison, USA, August 6–11 2006Google Scholar
- Fritsche J, Obrist D, Alewell C (2007) Evidence of microbial control of Hg0 emissions from uncontaminated terrestrial soils. J Plant Nutr Soil Sci (in press)Google Scholar
- Gustin MS, Marsik F, Obrist D (2006) Air-surface exchange of mercury in terrestrial ecosystems. In: Abstracts of the 8th international conference on mercury as a global pollutant, Madison, USA, August 6–11 2006Google Scholar
- Lindberg SE (1996) Forests and the global biogeochemical cycle of mercury: The importance of understanding air/vegetation exchange processes. In: Baeyens W, Ebinghaus R, Vasiliev O (eds) Global and regional mercury cycles: Sources, fluxes and mass balances. NATOASISeries, vol 21. Kluwer Academic Publishers, Dordrecht, pp 359–380Google Scholar
- Lindberg SE, Jackson DR, Huckabee JW et al (1979) Atmospheric emissions and plant uptake of mercury from agricultural soils near the Almaden mercury mine. J Environ Qual 8:572–578Google Scholar
- Pang SM (1997) Mercury in wood and wood fuels. Thesis, University of Minnesota, Minneapolis, MNGoogle Scholar
- Prentice IC, Farquhar GD, Fasham MJR et al (2001) The carbon cycle and atmospheric carbon dioxide. In: Climate change 2001: The scientific basis. Contribution of working group I to the third assessment report of the intergovernmental panel on climate change. Cambridge University Press, CambridgeGoogle Scholar
- Saugier BS, Roy J, Mooney HA (2001) Estimations of global terrestrial productivity: converging toward a single number? In: Roy J, Saugier B, Mooney HA (eds) Terrestrial global productivity. Academic Press, San Diego, pp 543–557Google Scholar
- Slemr F, Brunke E, Labuschagne C (2006) Long-term observations of total gaseous mercury at the Cape Point GAW Station, South Africa. In: Abstracts of the 8th international conference on mercury as a global pollutant, Madison, August 6–11 2006Google Scholar
- Steele LP, Krummel PB, Langenfelds RL (2002) In Trends: A compendium of data on global change. Carbon dioxide information analysis center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak RidgeGoogle Scholar
- Tans PP, Conway TJ (2005) In Trends: A compendium of data on global change. Carbon dioxide information analysis center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak RidgeGoogle Scholar
- Wickland K, Krabbenhoft D, Olund S (2006) Evidence for a link between soil respiration and mercury emission from organic soils. In: Abstracts of the 8th international conference on mercury as a global pollutant, Madison, August 6–11 2006Google Scholar