HR: 0830h
AN: B31E-0364    [PDF]
TI: Quantifying Reemission Of Mercury From Terrestrial And Aquatic Systems Using Stable Isotopes: Results From The Experimental Lakes Area METAALICUS Study
AU: * Lindberg, S E
EM: lindbergse@ornl.gov
AF: Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 United States
AU: Southworth, G
EM: sgr@ornl.gov
AF: Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 United States
AU: Peterson, M
EM: ppm@ornl.gov
AF: Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831 United States
AU: Hintelmann, H
EM: hhintelmann@trentu.ca
AF: Trent University, 1600 West Bank Drive, Peterborough, Ont K9J 7B8 Canada
AU: Graydon, J
EM: jgraydon@ualberta.ca
AF: University of Alberta, CW 405 Biological Sciences Centre, Edmonton, Alb T6G 2E9 Canada
AU: St. Louis, V
EM: vince.stlouis@ualberta.ca
AF: University of Alberta, CW 405 Biological Sciences Centre, Edmonton, Alb T6G 2E9 Canada
AU: Amyot, M
EM: m.amyot@umontreal.ca
AF: University of Montreal, C.P. 6128, Succ. Centre-ville, Montreal, Ont H2V 2S9 Canada
AU: Krabbenhoft, D
EM: dpkrabbe@usgs.gov
AF: USGS, 8505 Research Way, Middleton, WI 53562 United States
AB: This study represents the first attempt to directly quantify the re-emission of deposited Hg. This is crucial for understanding the sources of Hg emitted from natural surfaces as being of either geological origin or through re-emission of recently deposited Hg. Three stable Hg isotopes are being added experimentally to a headwater lake, wetlands, and its watershed in a whole-ecosystem manipulation study at the Experimental Lake Area in Canada. Our overall objective is to determine the link between atmospheric deposition and Hg in fish, but numerous aspects of the biogeochemical cycling of Hg are being addressed during METAALICUS (Mercury Experiment to Assess Atmospheric Loading in Canada and the U.S.), including Hg re-emission. Pilot studies in 1999-2000 applied enriched 200Hg to isolated upland and wetland plots, and to lake enclosures. Fluxes were measured with dynamic chambers for several months. The 200Hg spike was quickly detected in ground-level air (e.g. 5 ng/m3) suggesting rapid initial volatilization of the new Hg. Initial 200Hg fluxes $>$ ambient Hg, but emissions of 200Hg decreased within 3 months to non-detects; about 5% of the applied 200Hg spike was emitted from uplands and about 10% from wetlands. The 200Hg spike (representing new deposition) was generally more readily volatilized than was ambient (old) Hg in both sites. Mercury evasion to the atmosphere from a lake enclosure was also measured and compared with the flux estimated from measured dissolved gaseous mercury (DGM). The introduction of the tracer spike was followed by increased concentrations of DGM and higher fluxes to the atmosphere. In some cases, the observed and calculated fluxes were similar; however, it was common for the observed flux to exceed the calculated flux significantly under some conditions, suggesting that DGM concentration alone in the water column is a poor predictor of gaseous mercury evasion. A substantially larger fraction of the newly deposited Hg was re-emitted from the lake than from wetlands or from upland soils. The whole-ecosystem manipulation is now underway at ELA Lake 658. Addition of 200Hg (to uplands), 202Hg (lake), and 199Hg (wetlands) commenced in 2001 and was completed in June 2003. These data are now being analyzed, and appear to support the behavior seen in the pilot studies; final results will be presented.
UR: http://www.esd.ornl.gov/people/lindberg/lindberg.html
DE: 0315 Biosphere/atmosphere interactions
DE: 0322 Constituent sources and sinks
DE: 0330 Geochemical cycles
DE: 0345 Pollution--urban and regional (0305)
DE: 1065 Trace elements (3670)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting