Featuring Professor David A. Stahl
Department of Civil & Environmental Engineering, University of Washington

Human activities have greatly altered the forms and abundances of carbon and nitrogen in the environment. While the impacts of fossil fuel burning and deforestation receive the most attention, humans also profoundly alter the nitrogen economy by producing nitrogen for agriculture purposes. Although this is essential for sustaining half of the human population, the downside is great monetary and environmental costs, as the energy intensive process consumes up to 2% of the world's annual energy supply. To complicate matters, more than half of the nitrogen produced for agricultural purposes is lost as a consequence of microbial activity, cascading through the atmosphere and terrestrial, freshwater, and marine ecosystems. This contributes to nitrate contamination of groundwater, reduced soil fertility, regional nutrient imbalances, increased emissions of atmospherically active gases (NO and N2O), and extensive eutrophication of coastal regions.
The solution to better management of the nitrogen economy may lie in the smallest of biological life forms, as microbial activities facilitate the movement of nitrogen in various forms through the environment. Recent discoveries may help improve environmental management and lead to the development of energy efficient nitrogen removal and water reuse systems.