My primary research interests include the atmospheric chemistry, transport and biogeochemistry of mercury (Hg), in particular the quantification of its land-atmosphere exchange using micrometeorological methods. The main goal of my PhD research was to identify the role of boreal peatlands as net sinks or sources of Hg by calculating the first annual Hg budget including continuous measurements of the Hg peat-atmosphere exchange. Furthermore, I have performed air monitoring campaigns over contaminated soils in the Canton of Valais, to assess potential health risks for residents as a result of chronic inhalation of Hg vapor. During my Postdoc at the Department of Forest Ecology and Management , SLU, Umeå, I have designed and planned two comprehensive research projects on 1) water-atmosphere exchange of Hg from the Baltic Sea at the ICOS marine station Östergarnsholm, Gotland, Sweden and 2) on dynamics and fate of Hg in forest ecosystems at the ICOS Svartberget boreal forest flux station. Within the framework of the SNSF Sino-Swiss Science and Technology Cooperation we currently investigate Hg biogeochemical behaviour in Davos-Seehornwald forest in Switzerland and Mt. Changbai forest in NE-China to understand how different chronologies of Hg deposition impact Hg biogeochemistry in remote forest ecosystems with a specific focus on atmosphere-land exchange.
Publications in peer-reviewed scientific journals
Osterwalder, S., Sommar, J., Åkerblom, S., Jocher, G., Fritsche, J., Nilsson, M.B., Bishop, K. and Alewell, C.: Comparative study of elemental mercury flux measurement techniques over a Fennoscandian boreal peatland, Atmos. Environ. 172, 16-25, 2018.
Shetaya, W.H., Osterwalder, S., Bigalke, M., Mestrot, A., Huang, J.-H. and Alewell, C: An Isotopic Dilution Approach for Quantifying Mercury Lability in Soils. Environ. Sci. Technol. Lett, 2017.
Osterwalder, S., Bishop, K., Alewell, C., Fritsche, J., Laudon, H., Åkerblom, S. and Nilsson, M.B.: Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution, Scientific Reports 7, 16022, 2017.
Osterwalder, S., Fritsche, J., Alewell, C., Schmutz, M., Nilsson, M. B., Jocher, G., Sommar, J., Rinne, J. and Bishop, K.: A dual-inlet, single detector relaxed eddy accumulation system for long-term measurement of mercury flux, Atmos. Meas. Tech., 9, 509-524, 2016.
Fritsche, J., Osterwalder, S., Nilsson, M. B., Sagerfors, J., Åkerblom, S., Bishop, K. and Alewell, C.: Evasion of elemental mercury from a boreal peatland suppressed by long-term sulfate addition, Environ. Sci. Technol. Lett., 1, 421-425, 2014.
Ph.D. in Geosciences. Department of Forest Ecology and Management, SLU Umeå, Sweden and Environmental Sciences, University of Basel, Switzerland. Thesis title: “Land-atmosphere exchange of elemental mercury: New insights using a novel relaxed eddy accumulation system and enclosure techniques”. Advisors: Prof. Christine Alewell, Prof. Kevin Bishop, Prof. Mats B. Nilsson. External reviewer: Prof. Mae S. Gustin. Defense date: 17.05.2016. Mark: Summa cum laude
Master of Science (M.Sc.) in Environmental Geosciences. University of Basel. Field: Environmental Sciences and Meteorology
Bachelor of Science (B.Sc.) in Geosciences. University of Basel. Field: Pedology, Meteorology, Geology and Hydrology
Matura. Kantonsschule Wohlen. Field: Latin, Geography
01/2018 - today
Research scientist, Environmental Sciences, University of Basel. Science and Technology Cooperation with State Key Laboratory of Environmental Geochemistry (SKLEG), China.
11/2017 - 12/2017
Postdoctoral researcher, Environmental Sciences, University of Basel.
10/2016 - 10/2017
Postdoctoral researcher, Department of Forest Ecology and Management, SLU Umeå, Sweden: Investigating the role of the ocean and boreal forests in the global mercury cycle.
05/2016 - 09/2016
Project leader, Canton Valais, Sion and Arcadis Schweiz AG, Schlieren: Air quality monitoring during remediation of mercury contaminated soils and measurements of atmospheric Hg concentrations over the Gamsenried landfill.
03/2011 - 10/2011
Research assistant, SLU Uppsala, Sweden: Development of Hg measurement techniques.