Igor Lehnherr, Assistant Professor


Home Campus:
U o f T Mississauga

University of Alberta (Environmental Biology and Ecology)

Other Degrees:
BSc., University of Victoria (Chemistry and Biology double major)

Cross Appointments:
1) Institute of Management and Innovation
2) School of the Environment
3) Physical & Environmental Science

Contact Information:

Office: DV 3281 (UTM)
Phone: (905) 569-5769
Email: igor.lehnherr@utoronto.ca

Personal Website: https://igorlehnherr.weebly.com/

Research Interests:

  • Biogeochemistry of major and trace elements
  • Contaminants
  • Impacts of climate change on aquatic ecosystems
  • Arctic, boreal and alpine environments
  • Limnology and oceanography
  • Environmental chemistry

Teaching This Academic Year:

Geography Program:

GGR 227 – Ecosystems and Environmental Change

GGR 383 – Contaminants in the Environment

GGR 406 – Environmental Biogeochemistry

GGR 1216 – Advanced Biogeochemical Processes (Graduate-level course)

MSc Sustainable Management Program:

SSM 1030 – Environmental Science

SSM2030 – Directed Studies

Current Students:

I welcome motivated graduate (and undergraduate) students interested in physical geography, biogeochemistry and environmental science. My research aims to understand how environmental stressors, such as contaminants and climate change, impact aquatic ecosystems, particularly in the Canadian Arctic and boreal ecoregions. Current and potential projects include: i) impacts of climate change on mercury cycling and methylmercury production; ii) reconstructing long-term trends in atmospheric mercury using tree-rings, ice cores and sediment cores; iii) mercury and organic contaminant bioaccumulation in an estuarine foodweb in northern Labrador impacted by hydropower development; iv) quantifying ecosystem metabolism (primary production and respiration) in ice-covered lakes; and v) climate change impacts on lake and watershed biogeochemistry (carbon and nutrient cycling) in northern regions.

Selected Publications:

Refereed Publications (published or accepted; 2017 and 5-year impact factors (IF) included in parentheses):

  1. Clackett, S.P., T. Porter, and Lehnherr. A 400-year record of atmospheric mercury from tree-rings in northwestern Canada. Environmental Science & Technology, 52: 9625-9633 (IF: 6.2, 5-Year IF: 7.0).
  2. Lehnherr, I., V. St. Louis, M. Sharp, A. Gardner, J. Smol, S. Schiff, D. Muir, C. Mortimer, N. Michelutti, C. Tarnocai, K. St. Pierre, C. Emmerton, J. Wiklund, G. Köck, S. Lamoureux, C. Talbot. 2018. The world’s largest High Arctic lake responds rapidly to climate change. Nature Communications, 9: 1290 (IF: 12.1, 5-Year IF: 13.1).
  3. Willis, C.E., J. Kirk, V. St. Louis,  Lehnherr, P. Ariya and R. Rangel-Alvarado. 2018. Sources of methylmercury to snowpacks of the Alberta Oil Sands Region: a study of in situ methylation and particulatesEnvironmental Science & Technology, 52: 531-540.
  4. Emmerton, C.A., V. St. Louis, Lehnherr, J. Graydon, J. Kirk and K. Rondeau. 2016. The net exchange of carbon greenhouse gases with freshwater systems in a High Arctic watershed. Biogeosciences, 13: 5849-5863 (IF: 3.9, 5-Year IF: 4.6).
  5. Soerensen, A., D. Jacob, A. Schartup, J. Fisher, Lehnherr, V. St. Louis, L.-E. Heimburger, J. Sonke, E. Sunderland. 2016. A Mass Budget for Mercury and Methylmercury in the Arctic Ocean. Global Biogeochemical Cycles 30: 10.1002/2015GB005280 (IF: 4.7, 5-Year IF: 5.1).
  6. Pierre, K.A., V. St. Louis, J. Kirk, I. Lehnherr, S. Wang, C. La Farge. 2015. The importance of open marine waters to the enrichment of total mercury and monomethylmercury in lichens in the Canadian High Arctic. Environmental Science & Technology, 49: 5930-5938 (Featured on “Quirks & Quarks”, CBC Radio; IF: 6.2, 5-Year IF: 7.0).
  7. Steffen A.,  Lehnherr, A. Cole, P. Ariya, A. Dastoor, D. Durnford, J. Kirk, M. Pilote. 2015. Atmospheric Mercury in the Canadian Arctic. Part I: A review of recent field measurements. Science of the Total Environment, 509-510: 3-15 (IF: 4.9, 5-Year IF: 5.1).
  8. Dastoor A., A. Ryzhkov, D. Durnford, Lehnherr, I., A. Steffen. 2015. Atmospheric Mercury in the Canadian Arctic Part II: Insight from Modeling. Science of the Total Environment, 509-510: 16-27.
  9. Chételat, J. and 22 others, including Lehnherr. 2015. Mercury in freshwater ecosystems of the Canadian Arctic: Recent advances on its cycling and fate. Science of the Total Environment, 509-510: 41-66.
  10. Braune, B. and 18 others, including Lehnherr. 2015. Mercury in the marine environment of the Canadian Arctic: A review of recent data. Science of the Total Environment, 509-510: 67-90.
  11. Baya, P.A., M. Gosselin, Lehnherr, V. St. Louis and H. Hintelmann. 2015. Determination of monomethylmercury and dimethylmercury in the Arctic lower atmosphere. Environmental Science & Technology, 49: 223-232.
  12. Kirk, J.L., D.C.G. Muir, A. Gleason, X. Wang, R. Frank and Lehnherr. 2014. Atmospheric deposition of mercury and methylmercury to landscapes and waterbodies of the Athabasca Oil Sands Region. Environmental Science & Technology, 48: 7374-7383. (American Chemical Society Editor’s Choice)
  13. Emmerton, C.A., V.L. St. Louis, Lehnherr, E.R. Humphreys, E. Rydz, and H. Kosolofski. 2014. Net exchange of methane with high Arctic landscapes during the summer growing season. Biogeosciences, 11: 3095-3106.
  14. Lehnherr, I. Methylmercury biogeochemistry: A review with special reference to Arctic aquatic ecosystems. Environmental Reviews, 22: 229-243. (Editor’s Choice; IF: 3.2, 5-Year IF: 5.0)
  15. Kirk, J. L., Lehnherr (co-lead author), M. Andersson, B. Braune, L. Chan, A. P. Dastoor, D. Durnford, A. Gleason, L. Loseto, A. Steffen, and V. St. Louis. 2012. Mercury in Arctic marine environments: sources, pathways and exposure. Environmental Research, 119: 64-87. (IF: 3.8, 5-Year IF: 4.3)
  16. Lehnherr, I., V. L. St. Louis, C. A. Emmerton, J. D. Barker and J. L. Kirk. 2012. Methylmercury cycling in high Arctic wetlands: sources and sinks. Environmental Science & Technology, 46: 10514-10522. (Featured on the cover of ES&T)
  17. Lehnherr, I., J. L. Kirk and V. L. St. Louis. 2012. Methylmercury cycling in high Arctic wetlands: controls on sedimentary production. Environmental Science & Technology, 46: 10523-10531. (Featured on the cover of ES&T)
  18. Lehnherr, I., V. L. St. Louis, H. Hintelmann and J. L. Kirk. 2011. Methylation of inorganic mercury in polar marine waters. Nature Geoscience, 4: 298-302. (IF: 13.9, 5-Year IF: 14.4)
  19. Louis, V. L., A. Derocher, I. Stirling, J. A. Graydon, C. Lee, E. Jocksch, E. Richardson, S. Ghorpade, A. K. Kwan, J. L. Kirk, I. Lehnherr and H. K. Swanson. 2011. Climate-induced changes in foodweb structure affecting mercury levels in Polar Bears (Ursus maritimus). Environmental Science & Technology, 45: 5922-5928.
  20. Mowat, L. D., V. L. St. Louis, J. A. Graydon, and Lehnherr. 2011. Influence of forest canopies on the deposition of methylmercury to boreal ecosystem watersheds. Environmental Science & Technology 45: 5178-5185.
  21. Lehnherr, I. and V. L. St. Louis. 2009. Importance of ultraviolet radiation in the photodemethylation of methylmercury in freshwater ecosystems. Environmental Science & Technology 43: 5692-5698.
  22. Graydon, J. A., V. L. St. Louis, H. Hintelmann, S. E. Lindberg, K. A. Sandilands, J. W. M. Rudd, C. A. Kelly, M. T. Tate, D. P. Krabbenhoft, and Lehnherr. 2009. Investigation of uptake and retention of atmospheric Hg(II) by boreal forest plants using stable Hg isotopes. Environmental Science & Technology 43: 4960-4966.
  23. Kirk, J. L., V. L. St. Louis, H. Hintelmann, Lehnherr, B. Else and L. Poissant. 2008. Methylated mercury species in marine waters of the Canadian high and sub Arctic. Environmental Science & Technology 42: 8367-8373.
  24. St. Louis, V. L., H. Hintelmann, J. A. Graydon, J. L. Kirk, J. Barker, B. Dimock, M. J. Sharp, and I. Lehnherr. 2007. Methylated mercury species in polar marine surface water and snowpacks. Environmental Science & Technology 41: 6433-6441.

Book Chapters

  1. Lehnherr, I. (lead author) and 17 others. 2016. Mercury Fate and Methylation in Freshwater Aquatic Ecosystems. Ch. 6. In: Canadian Mercury Assessment Report, Ed. A. Steffen. Environment Canada, Clean Air Regulatory Agenda Mercury Science Program.
  2. Chételat, J. and 22 others, including Lehnherr. 2012. Freshwater Environment. Ch. 5. In: Canadian Arctic Contaminants Assessment Report III: Mercury in Canada’s North. Eds. J. Chételat and B. Braune. Aboriginal Affairs and Northern Development Canada, Northern Contaminants Program.
  3. Chételat, J. and 19 others, including Lehnherr. 2012. Marine Environment. Ch. 6. In: Canadian Arctic Contaminants Assessment Report III: Mercury in Canada’s North. Eds. J. Chételat and B. Braune. Aboriginal Affairs and Northern Development Canada, Northern Contaminants Program.

Research Clusters:
Biogeochemistry and Contaminants, Climate Processes and Climate and Carbon Cycle Modelling, Earth-Surface Processes and Hydrology