Igor Lehnherr

My Research Interests

In the Environmental and Aquatic Biogeochemistry Laboratory, we conduct research to understand the impacts of environmental stressors such as contaminants, nutrients, and climate change on aquatic ecosystems, focusing primarily on the Arctic and Boreal ecoregions. A biogeochemical perspective is required because many environmental problems, including heavy metal pollution, eutrophication and climate change, are caused by anthropogenic disturbances to natural biogeochemical cycles. Our research is interdisciplinary – integrating physical geography, limnology, environmental chemistry, and ecology – and combines emerging analytical techniques, ecosystem-scale field studies and controlled experiments to elucidate how humans impact the natural world we live in.

I participate in the following research clusters:

Environmental Processes & Change in Natural Systems

Graduate Student Recruitment

I welcome motivated graduate students interested in physical geography, biogeochemistry and environmental science. Current and potential projects include: i) impacts of climate change on mercury cycling and methylmercury production in Arctic ecosystems; ii) quantifying ecosystem metabolism (primary production and respiration) in ice-covered Arctic lakes; iii) reconstructing long-term trends in atmospheric mercury concentrations using tree-rings and ice cores; and iv) climate change impacts on lake and watershed biogeochemistry (carbon and nutrient cycling) in northern regions. Interested students are encouraged to please contact me for the most up to date information on potential opportunities at the undergraduate, graduate and post-doc levels. Please include with your inquiry a copy of your CV and latest transcripts.

Selected Publications

Lehnherr, I., St. Louis, V. L., Sharp, M., Gardner, A. S., Smol, J. P., Schiff, S. L., Muir, D. C. G., Mortimer, C. A., Michelutti, N., Tarnocai, C., St. Pierre, K. A., Emmerton, C. A., Wiklund, J. A., Köck, G., Lamoureux, S. F., Talbot, C. H. 2018. The world's largest High Arctic lake responds rapidly to climate change. Nature Communications, 9: 1290 (IF: 12.121, 5-Year IF: 13.610). (#24 on the Top 50 most read Nature Communications Earth and Planetary Sciences articles published in 2018) https://www.nature.com/articles/s41467-018-03685-z

*Varty, S. E. M., Lehnherr, I., St. Pierre, K. A., Kirk, J. L., *Wisniewski, V. E. 2021. Methylmercury transport and fate shows strong seasonal and spatial variability along a high Arctic freshwater hydrologic continuum. Environmental Science & Technology, Environmental Science & Technology, 55: 331-340. (IF: 7.864, 5-Year IF: 8.543).

**Ghotra, A., Lehnherr, I., Porter T. J., Pisaric, M. F. J. 2020. Tree-Ring Inferred Atmospheric mercury concentrations in the Mackenzie Delta (NWT, Canada) peaked in the 1970s but are increasing once more. ACS Earth and Space Chemistry, 4: 457-466

MacInnis, J. J., Lehnherr, I., Muir, D. C. G., Quinlan, C. R., De Silva, A. O. 2019. Characterization of perfluoroalkyl substances in sediment cores from Canadian High and Low Arctic lakes. Science of the Total Environment, 666: 414-422 (IF: 6.551, 5-Year IF: 6.419).

St. Pierre, K. A., St. Louis, V. L., Schiff, S. L., Lehnherr, I., Dainard, P. G., Gardner, A. S., Aukes, P. J. K., Sharp, M. J. 2019. Proglacial freshwaters are significant and previously unrecognized sinks of atmospheric CO2. Proceedings of the National Academy of Sciences, 116: 17690-17695 (IF: 9.412, 5-Year IF: 10.620).

(* indicates graduate student or post-doctoral fellow, ** indicates undergraduate students under my supervision)