Atmospheric Fate and Transport of Toxic Air Pollutants

Dr. Mark Cohen

Dr. Mark Cohen's work at the NOAA Air Resources Laboratory primarily involves modeling the atmospheric fate and transport of toxic air pollutants. This work has been performed in collaboration with a number of scientists from NOAA Air Resources Laboratory, including Roland Draxler and Richard Artz, and a number of scientists from the EPA, IJC, CEC, and other institutions. A particular focus of this work has been the development of information regarding source-receptor relationships for atmospheric deposition. That is, a goal of the modeling analysis has been to attempt to determine the relative contributions of different sources and source regions to the overall atmospheric deposition to any given receptor (e.g., a Great Lake). A review of the emission, monitoring, fate and transport of toxic air pollutants in relation to the Great Lakes was performed for the International Joint Commission (IJC) in 1997 [1], [2], [3], [4], [5] (before Dr. Cohen began working at ARL). Overview presentations regarding atmospheric toxics include those given to a meeting convened by the National Park Service [6], an EPA conference on Persistent and Bioaccumulative Toxics (PBT) [7], and the 25th Anniversary National Acid Deposition Program Meeting [8]. In recent years, Dr. Cohen's work has focused primarily on three different pollutants: dioxin, atrazine and mercury.

Dioxin. A summary [9] of the dioxin pollution situation was prepared for the Commission for Environmental Cooperation (CEC) in connection with their Continental Pollutant Pathways initiative. A presentation was given at Dioxin 2000 in Monterey California, and an extended abstract of the talk [10] is available from Organohalogen Compounds. A white paper [11] was presented [12] regarding the atmospheric deposition of dioxin to Lake Michigan at a meeting organized by the Delta Institute. A paper [13] (with Supplemental Information [14]) regarding the atmospheric transport and deposition of dioxin to the Great Lakes was published in Environmental Science and Technology in 2002.

Atrazine. A report [41] was prepared in 1997 (prior to Dr. Cohen's appointment at the Air Resources Laboratory) estimating atmospheric emissions, fate and transport, and source-receptor relationships for atrazine in the U.S. and Canada. Maps [42] showing the week-by-week estimates of atrazine emissions for 1991 were prepared in 1999.

Mercury.

• General Overviews: A talk [26] (with accompanying movie [27]) regarding source-attribution aspects of atmospheric chemistry was given at the 2004 USGS Mercury Workshop in Reston, VA. An expanded version of this presentation was given at the MARAMA Mercury Workshop in Cherry Hill, NJ [28]. An overview of mercury emissions, atmospheric fate and transport, and source-receptor relationships was given as given at a January 2006 Niagara Falls meeting organized by the U.S. EPA, the IJC, and the Ontario Ministry of the Environment [39], and an April 2006 seminar at Frostburg State University [43] . An overview of local and regional deposition impacts was given at a Nov 2005 meeting of the Pennsylvania Department of Environmental Protection Mercury Rule Workgroup [37]. An overview of data needs for atmospheric mercury model evaluation was presented at an Oct 2005 meeting in Frostburg MD [38]. An overview presentation regarding mercury fate and transport in the environment was presented to the NOAA OAR Ecosystem Research Program in February 2005 [29].

• Model Intercomparisons: A presentation highlighting the value of intercomparisons was given at a January 2006 EPA-IJC-OMOE meeting in Niagara Falls; this presentation summarized several examples for mercury, including the study described below, a comparison of HYSPLIT vs. ISC for near-field deposition, and a comparison of HYSPLIT vs. CMAQ for the impact of U.S. coal-fired power plants on the Great Lakes [40]. Simulation of mercury in a European modeling domain has been performed as part of a Mercury Modeling Intercomparison Project, organized by MSC-East in Moscow, Russia. HYSPLIT results from Phase II of this Intercomparison are available [24], as well as a 2003 report describing all results for Phase II [25]. A 2005 report describes the results for Phase III [35]. A presentation was given in October 2005 summarizing the results of the entire Mercury Modeling Intercomparison study [36]. [Note: Phase I results and the above reports are available on the main Project link given above.]. The Phase II and Phase III results have also been summarized in publications: [49] and [50]

• NOAA Report to Congress on Great Lakes Mercury Contamination: A report on Mercury Contamination in the Great Lakes was submitted to Congress on May 14, 2007, co-authored by Mark Cohen, Roland Draxler, and Richard Artz. The report was requested by the Conference Report accompanying the Consolidated Appropriations Act, 2005 (H. Rpt. 108-792). The report focuses on two areas: (1) the fate and transport of atmospheric mercury, including an analysis of the atmospheric transport and deposition of U.S. and Canadian anthropogenic mercury emissions to the Great Lakes using the NOAA HYSPLIT-Hg atmospheric mercury model; and (2) data regarding trends in Great Lakes mercury contamination, including trends in mercury air emissions and deposition, and in mercury concentrations in sediments, fish, and other biota. The report is available at: http://www.arl.noaa.gov/data/web/reports/cohen/NOAA_GL_Hg.pdf [53]

• Great Lakes (1996 analysis): A presentation regarding the atmospheric deposition of mercury to the Great Lakes [15] was given at the IJC-organized symposium An Ecosystem Approach to the Health Effects of Mercury in the Great Lakes Basin. A paper [16] (with Supporting Information [17]) was published in a special issue of the journal Environmental Research dedicated to papers arising from this meeting.

• Great Lakes (1999 analysis): The 1996 analysis for the Great Lakes was updated using 1999-2000 emissions inventories [18]. A presentation regarding the transport and deposition of mercury to Lake Michigan was presented to the Indiana Dept of Environmental Management's Mercury Working Group meeting in April 2005 [30]. A presentation regarding the transport and deposition of mercury to Lake Ontario was presented at the IJC's Biennial Meeting in Kingston, Ontario, Canada, in June 2005 [31].

• Chesapeake Bay region: An analysis for the Chesapeake Bay was presented to the NOAA Chesapeake Bay program office [20] and at the 7th International Conference on Mercury as a Global Pollutant (ICMGP) in Slovenia in 2004 [21]. A poster presenting preliminary results from a Summer 2004 atmospheric mercury study in the Chesapeake Bay region was presented at the NADP meeting in Halifax, NS (Sept 2004) [32]. In August 2005, overview talks focusing on the Chesapeake Bay region were given to the Maryland Department of the Environment [33] and the Baltimore City Department of Law [34]. Additional analyses of the Summer 2004 data and plans for a new monitoring program at Beltsville MD were presented at the 8th International Conference on Mercury as a Global Pollutant (ICMGP) in Madison Wisconsin in August 2006 [46]

• Lake Champlain: An analysis for Lake Champlain [19] was presented at a 2003 symposium organized by NOAA Sea Grant in Burlington VT.

• Gulf of Mexico region: Source-receptor modeling results for Mobile Bay were presented at the Gulf Coast Mercury Research Collaboration Meeting in Pensacola Florida in May 2006 [44]. An introductory set of slides has been prepared describing a new atmospheric mercury monitoring site being established at the Grand Bay NERR in Mississippi [45].

• Rock Creek Watershed: Source-receptor modeling results for the Rock Creek Watershed (in the Washington DC area) were presented at a NOAA Atmospheric Mercury meeting in Silver Spring, Nov 2006 [47].

• Impacts of Future Emissions: A report [22] and presentation [23] were prepared for the CEC, dealing with the potential consequences of future mercury emissions scenarios.

• Mercury Trends: A report [51] and poster [52] were prepared discussing trends in Mercury Deposition Network data. The report also includes an overview of atmospheric mercury fate/transport and a detailed section examining source-receptor case-studies for mercury wet deposition events associated with individual storms. The NOAA Report to Congress [53] listed above also has an extensive section on mercury trends in the Great Lakes.

• Multi-Media Modeling: A presentation [48] regarding ongoing efforts to link atmospheric mercury models with mercury models in other media was given at the Contaminant Monitoring & Research Workshop Planning for the 2008 Cooperative Monitoring Year (Contaminants Component), Grand Island, New York, March 2007.

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  Documents available for viewing or download:

  Overviews

  • 1. IJC Review Part 1 (Atmospheric Fate): Cohen, M., Long Range Transport of Persistent Atmospheric Pollutants. Windsor, Ontario: IJC. Prepared for the International Joint Commission's International Air Quality Advisory Board, 1997
  
  
  
  • 2. IJC Review Part 2 (Emissions): Cohen, M., Evaluation of Emissions Inventories in the U.S. and Canada for Level I and Level II Pollutants. Windsor, Ontario: IJC. Prepared for the International Joint Commission's International Air Quality Advisory Board, 1997.
  
  
  
  • 3. IJC Review Part 3 (Monitoring): Cohen, M., and P. Cooney, The Use of Ambient Monitoring to Estimate the Atmospheric Loading of Persistent Toxic Substances to the Great Lakes. Windsor, Ontario: IJC. Prepared for the International Joint Commission's International Air Quality Advisory Board, 1997.
  
  
  
  • 4. IJC Review Part 4 (Modeling): Cohen, M., Modeling the Atmospheric Transport and Deposition of Persistent Toxic Pollutants to the Great Lakes. Windsor, Ontario: IJC. Prepared for the International Joint Commission's International Air Quality Advisory Board, 1997.
  
  
  
  • 5. IJC Review Part 5 (Summary): Cohen, M., et al., The Transport and Deposition of Persistent Toxic Substances to the Great Lakes. Windsor, Ontario: IJC. Prepared for the International Joint Commission's International Air Quality Advisory Board, 1997.
  
  
  
  • 6. Atmospheric Processes: Transport of Air Toxics, Source-Receptor Relationships. Presentation at the National Park Service's Air Toxics Workshop, Seattle, WA , June 26-27, 2001
  
  
  
  • 7. Linkages Between Monitoring and Modeling of PBT's. Presentation at the US EPA's PBT Monitoring Strategy Workshop (also available as as a PowerPoint presentation [16 MB]), April 22-24, 2002, Raleigh, North Carolina.
  
  
  
  • 8. Linkages Between Environmental Monitoring and Modeling (also available as as a PowerPoint presentation [8 MB]). Presentation at NADP 2003: Long Term Monitoring: Supporting Science and Informing Policy, October 20-22, 2003, Washington DC
  
  
  

  Dioxin

  • 9. Cohen, M., B. Commoner, D. Muir, C. Santos-Burgoa, A. Espitia-Cabrera, Continental Pollutant Pathways: Dioxin. NAFTA Commission for Environmental Cooperation's Continental Pollutant Pathways Report, Case Study Volume, 1997.
  
  
  
  • 10. Cohen, M., Mathewson, L., Artz, R., and Draxler, R., The Atmospheric Transport and Deposition Of Dioxin to the Great Lakes. Organohalogen Compounds 45: 252-255, 2000.
  
  
  
  • 11. Cohen, M. The Transport and Deposition of Dioxin to Lake Michigan: A Case Study. A White Paper prepared for the symposium Using Models to Develop Air Toxics Reduction Strategies: Lake Michigan as a Test Case, Milwaukee, Wisconsin, Nov 8-9, 2000, organized by the International Joint Commission and the Delta Institute.
  
  
  
  • 12. Cohen, M. The Transport and Deposition of Dioxin to Lake Michigan: A Case Study. Presentation at the symposium Using Models to Develop Air Toxics Reduction Strategies: Lake Michigan as a Test Case, Milwaukee, Wisconsin, Nov 8-9, 2000, organized by the International Joint Commission and the Delta Institute.
  
  
  
  • 13. Cohen, M., Draxler, R., Artz, R., et al., Modeling the Atmospheric Transport and Deposition of PCDD/F to the Great Lakes. Environ. Sci. Technol. 36, 4831-4845, 2002.
  
  
  
  • 14. Supplementary Information for Cohen, M., Draxler, R., Artz, R., et al., Modeling the Atmospheric Transport and Deposition of PCDD/F to the Great Lakes. Environ. Sci. Technol. 36, 4831-4845, 2002.
  
  
  

  Atrazine

  • 41. Exposure To Endocrine Disrupters From Long-Range Air Transport Of Pesticides. Mark Cohen, Barry Commoner, Paul W. Bartlett, Paul Cooney, Holger Eisl. Final report submitted to the W. Alton Jones Foundation, November 17, 1997, Center For The Biology Of Natural Systems, Queens College, CUNY, Flushing, NY 11367. This study involved developing an atrazine emissions inventory for the U.S. and Canada and applying a specially configured version of the NOAA HYSPLIT model to estimate the fate and transport of atrazine emitted to the air. Source-receptor relationships for the Great Lakes and other selected receptors are estimated.
  
  
  
  • 42. Maps showing week-by-week estimates of atrazine emissions during 1991 (also available as as a PowerPoint presentation [16 MB]). Prepared in 1999 by Larissa Mathewson-Brake (Ontario Ministry of Natural Resources) and Mark Cohen based on analysis conducted in report immediately above.
  
  
  

  Mercury

  • 15. The Atmospheric Deposition of Mercury to the Great Lakes (also available as as a PowerPoint presentation [11 MB]). Presentation at An Ecosystem Approach to the Health Effects of Mercury in the Great Lakes Basin February 26-27, 2003, Windsor, Ontario.
  
  
  
  • 16. Cohen, M., Artz, R., Draxler, R., Miller, P., Poissant, L., Niemi, D., Ratte, D., Deslauriers, M., Duval, R., Laurin, R., Slotnick, J., Nettesheim, T., and McDonald, J. (2004). Modeling the Atmospheric Transport and Deposition of Mercury to the Great Lakes. Environmental Research 95(3), 247 265.
  
  
  
  • 17. Supplementary Information for: Cohen, M., Artz, R., Draxler, R., Miller, P., Poissant, L., Niemi, D., Ratte, D., Deslauriers, M., Duval, R., Laurin, R., Slotnick, J., Nettesheim, T., and McDonald, J. (2004). Modeling the Atmospheric Transport and Deposition of Mercury to the Great Lakes. Environmental Research 95(3), 247 265.
  
  
  
  • 18. The Atmospheric Transport and Deposition of Mercury to the Great Lakes (1999 updates) (also available as as a PowerPoint presentation [10 MB]) . Information prepared for the IJC Air Quality Advisory Board, April 16, 2004.
  
  
  
  • 19. Modeling the Atmospheric Deposition of Mercury to Lake Champlain (from Anthropogenic Sources in the U.S. and Canada) (also available as as a PowerPoint presentation [11 MB]). Presentation at the Workshop on Coordination of Atmospheric Deposition Research in the Lake Champlain Basin, June 5-6, 2003, Burlington, Vermont.
  
  
  
  • 20. Modeling the Fate and Transport of Atmospheric Mercury in the Chesapeake Bay Region (also available as as a PowerPoint presentation [11 MB]). Presentation at NOAA Chesapeake Bay Office, May 17, 2004, Annapolis, MD.
  
  
  
  • 21. Modeling the Transport and Deposition of Atmospheric Mercury to the Great Lakes (and the Chesapeake Bay) (also available as as a PowerPoint presentation [11 MB]). Presentation at the 7th International Conference on Mercury as a Global Pollutant (ICMGP), Llubljana, Slovenia, June 27-July 2, 2004.
  
  
  
  • 22. Atmospheric Mercury Deposition Impacts of Future Electric Power Generation. Final Report. Mark Cohen, NOAA Air Resources Laboratory, Silver Spring, MD. Project Manager and Co-Investigator: Paul J. Miller, Program Coordinator, Air Quality, Commission for Environmental Cooperation, Montreal, Quebec, Canada. Prepared for the Commission for Environmental Cooperation. December 8, 2003.
  
  
  
  • 23. Atmospheric Mercury Deposition Impacts of Future Electric Power Generation (also available as as a PowerPoint presentation [9 MB]). Presentation at Mercury in the Great Lakes Region, Sponsored by the Commission for Environmental Cooperation's Environment, Economy and Trade and Pollutants and Health Programs in cooperation with the Binational Toxic Strategy, Wednesday December 17th, 2003, Chicago, IL.
  
  
  
  • 24. HYSPLIT Modeling in Phase II of the EMEP Mercury Modeling Intercomparison Study (also available as as a PowerPoint presentation [4 MB]). Presentation at the Expert Meeting on Mercury Model Comparison, MSC-East, Moscow, Russia, April 15-16, 2003
  
  
  
  • 25. Intercomparison Study of Numerical Models for Long-Range Atmospheric Transport of Mercury. Stage II.. Ryaboshapko, A., R. Artz, O. Bullock, J. Christensen, M. Cohen, A. Dastoor, D. Davignon, R. Draxler, R. Ebinghaus, L. Ilyin, J. Mumthe, G. Petersen, D. Syrakov. Meteorological Synthesizing Centre - East, Cooperative Programme for Monitoring and Evaulation of the Long-Range Transmission of Air Pollutants in Europe. MSC-East: Moscow, Russia, 2003.
  
  
  
  • 26. Source-Apportionment for Mercury Deposition: Where Does the Mercury in Mercury Deposition Come From? (also available as as a PowerPoint presentation [11 MB]). Presentation at the USGS Mercury Workshop, August 17-18, 2004, Reston, Virginia.
  
  
  
  • 27. Movie Showing Variations in Daily Deposition Flux for a Hypothetical Emissions Source of Reactive Gaseous Mercury, Accompanying "Source-Apportionment for Mercury Deposition: Where Does the Mercury in Mercury Deposition Come From?" (also available as as a PowerPoint presentation [9 MB]).Presented at the USGS Mercury Workshop, August 17-18, 2004, Reston, Virginia.
  
  
  
  • 28. Source-Apportionment for Mercury Deposition: Where Does the Mercury in Mercury Deposition Come From? (also available as a PowerPoint presentation [11 MB]). Presentation at the MARAMA Mercury Workshop, September 13-14, 2004, Cherry Hill, NJ.
  
  
  
  • 29. Opportunities for Mercury Collaboration between the Air Resources Laboratory and the Ecosystem Research Program (also available as a PowerPoint presentation [29 MB]). Presentation to the NOAA Ecosystem Research Program, Feb 16, 2005, Silver Spring, MD.
  
  
  
  • 30. Source-attribution for atmospheric mercury deposition: Where does the mercury in mercury deposition come from? (also available as a PowerPoint presentation [7 MB]) Presentation to the Mercury Working Group, Office of Air Quality, Indiana Department of Environmental Management, via speakerphone, April 21, 2005. General overview of atmospheric mercury modeling and source-receptor relationships. Also includes detailed results for Lake Michigan.
  
  
  
  • 31. Modeling the Atmospheric Transport and Deposition of Mercury (also available as a PowerPoint presentation [10 MB]). Presentation at the IJC Biennial Meeting, June 9, 2005, Kingston, Ontario. General overview of atmospheric mercury modeling, including discussion of challenges faced. Also includes detailed results for Lake Ontario.
  
  
  
  • 32. Atmospheric Mercury in the Chesapeake Bay Region: A Measurement and Modeling Study (also available as a PowerPoint file [7 MB]). Poster presented at the NADP Meeting, Halifax, NS, Sept, 2004. Includes preliminary results for mercury measurements collected Summer 2004 at two sites on the Eastern Shore of the Chesapeake Bay.
  
  
  
  • 33. Modeling the Atmospheric Transport and Deposition of Mercury (also available as a PowerPoint file [24 MB]). Presentation to the Maryland Department of the Environment, Aug 25, 2005. General overview of atmospheric mercury modeling, including results for Deep Creek Lake.
  
  
  
  • 34. Modeling the Atmospheric Transport and Deposition of Mercury (also available as a PowerPoint file [26 MB]). Presentation for Baltimore City Dept of Law, Aug 25, 2005. General overview of atmospheric mercury modeling, including discussion of relative importance of local, regional, continental, and global sources.
  
  
  
  • 35. Intercomparison Study of Numerical Models for Long Range Atmospheric Transport of Mercury. Stage III. Comparison of Modelling Results with Long-Term Observations and Comparison of Calculated Items of Regional Balances . Ryaboshapko, A., Artz, R., Bullock, R., Christensen, J., Cohen, M., Draxler, R., Ilyin, I., Munthe, J., Pacyna, J., Petersen, G., Syrakov, D., Travnikov, O. Meteorological Synthesizing Centre - East, Moscow, Russia, 2005.
  
  
  
  • 36. EMEP Intercomparison Study of Numerical Models for Long-Range Atmospheric Transport of Mercury (also available as a PowerPoint file [2 MB]). Presentation at the EMEP/TFMM Workshop on the Review of the MSC-E Models on HMs and POPs, Oct 13-14, 2005, Moscow, Russia. Summary of Phases I, II, and III of the Mercury Modeling Intercomparison Project
  
  
  
  • 37. Local and Regional Deposition Impacts of Atmospheric Mercury Emissions (also available as a PowerPoint file [26 MB]). Presentation to the Mercury Rule Workgroup, Pennsylvania Department of Environmental Protection, Harrisburg, PA, November 18, 2005. General overview of atmospheric mercury modeling, and includes discussion of plume chemistry, and the potential importance of local and regional impacts of mercury emissions.
  
  
  
  • 38. Modeling the Atmospheric Transport and Deposition of Mercury (also available as a PowerPoint file [13 MB]). Presentation at "Mercury in Maryland" Meeting, Appalachian Lab, Univ. of Maryland Center for Environmental Science, Frostburg MD, Nov 2-3, 2005. General overview of atmospheric mercury modeling, and includes discussion of the relative merits of different types of ambient measurements for use in model evaluation.
  
  
  
  • 39. Atmospheric Mercury: Emissions, Transport/Fate, Source-Receptor Relationships (also available as a PowerPoint file [15 MB]). Presentation at the Collaborative Meeting on Modeling Mercury in Freshwater Environments, organized by IJC, EPA, and the Ontario Ministry of the Environment. Niagara Falls, NY, January 19-20, 2006. General overview of atmospheric mercury modeling, including current challenges faced, and detailed results for Lake Erie. Also includes a discussion of global anthropogenic emissions, natural emissions, and re-emissions, and a comparison of emissions in the U.S., Canada, and China.
  
  
  
  • 40. Atmospheric Mercury Model Intercomparisons (also available as a PowerPoint file [10 MB]). Presentation at the Collaborative Meeting on Modeling Mercury in Freshwater Environments, organized by IJC, EPA, and the Ontario Ministry of the Environment. Niagara Falls, NY, January 19-20, 2006. Discussion of the importance of model intercomparisons, and gives examples of HYSPLIT-Hg results compared to many other models, including CMAQ and ISC.
  
  
  
  • 43. Atmospheric Mercury: Emissions, Transport/Fate, Source-Receptor Relationships (also available as a PowerPoint file [35 MB]). Presentation at the Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg State University, April 27, 2006
  
  
  
  • 44. Atmospheric Mercury Modeling at the NOAA Air Resources Laboratory using the HYSPLIT-Hg Model (also available as a PowerPoint file [11 MB]). Presentation at the Gulf Coast Mercury Research Collaboration Meeting , in Pensacola FL, May 18-19, 2006. Overview of HYSPLIT-Hg modeling and source-receptor results for Mobile Bay.
  
  
  
  • 45. NOAA's Atmospheric Mercury Monitoring in the Gulf of Mexico Region (also available as a PowerPoint file [4 MB]). A summary of activities related to the new atmospheric mercury monitoring site at the Grand Bay NERR in Mississippi.
  
  
  
  • 46. Simulating the Atmospheric Fate and Transport of Mercury using the NOAA HYSPLIT Model (also available as a PowerPoint file [19 MB]). Presentation at the 8th International Conference on Mercury as a Global Pollutant, Madison Wisconsin, August 2006. Analysis of Summer 2004 ambient Hg measuurements at Oxford, MD, and discussion of new monitoring site plans at Grand Bay NERR, MS and Beltsville MD.
  
  
  
  • 47. Simulating the Atmospheric Fate and Transport of Mercury using the NOAA HYSPLIT Model (also available as a PowerPoint file [5 MB]). Presentation at the NOAA Atmospheric Mercury Meeting November 14-15, 2006, Silver Spring MD. Includes overview of current modeling activities and results for Rock Creek MD watershed.
  
  
  
  • 48. Atmospheric Fate and Transport of Mercury (also available as a PowerPoint file [8 MB]). Presentation at the Lake Ontario Contaminant Monitoring & Research Workshop Planning for the 2008 Cooperative Monitoring Year (Contaminants Component), Grand Island Holiday Inn, Grand Island, New York, March 27 & 28, 2007. Includes discussions of: (a) ongoing efforts to link atmospheric mercury models with mercury models in other media; (b) atmospheric modeling needs and goals; (c) results for Lake Ontario .
  
  
  
  • 49. Intercomparison study of atmospheric mercury models: 1. Comparison of models with short-term measurements . Ryaboshapko et al. (2007), Science of the Total Environment 376: 228-240.
  
  
  
  • 50. Intercomparison study of atmospheric mercury models: 2. Modelling results vs. long-term observations and comparison of country deposition budgets. Ryaboshapko et al. (2007), Science of the Total Environment 377: 319-333.
  
  
  
  • 51. Mercury in the Environment and Patterns of Mercury Deposition from the NADP/MDN Mercury Deposition Network . Final Report to USEPA Clean Air Markets Division, January 2007. Authors: Tom Butler and Gene Likens (Institute of Ecosystem Studies), Mark Cohen (NOAA Air Resources Lab), and Françoise Vermeylen (Cornell University).
  
  
  
  • 52. Mercury at MDN sites, 1998-2005: Declines in the Northeast, No Change in the Southeast (also available as a PowerPoint file [2 MB]). Authors: Tom Butler, Gene Likens, Mark Cohen, Francoise Vermeylen, David Schmeltz and Richard Artz. Poster presented by Tom Butler at the National Atmospheric Deposition Program 29th Annual Technical Meeting - NADP 2006: Effects of Deposition in Coastal and Urban Environments. Norfolk, Virginia, 24-26 October 2006.
  
  
  
  • 53. NOAA Report to Congress on Great Lakes Mercury Contamination . Authors: Mark Cohen, Roland Draxler, and Richard Artz. Submitted to Congress on May 14, 2007.