My research interests include quantification of exchange processes of pollutants and other atmospheric species between soils, plants, and the atmosphere, with an emphasis on how human activities (e.g., anthropogenic emissions, global change) affect these processes. Current research projects focus on the biogeochemical cycling of mercury in soils and the environment, the importance of long-range transport of atmospheric pollutants (e.g., Asian pollution events) for the Western United States, and development of optical sensors to measure atmospheric pollutants. Past research projects included the study of effects of large wildfires and global change (e.g., elevated CO2, increasing tropospheric ozone) on hydrologic processes and carbon/nutrient cycling in arid and alpine ecosystems. An important focus of my research has always been the development and application of new techniques to measure exchange fluxes at the level of whole ecosystems. Such methods include large static chambers, gradient-based micrometeorological methods, and atmospheric measurements in stable nocturnal boundary layers to quantify large-scale emission and deposition processes.