Descriptions of soil emissions of reactive nitrogen (NOy) in climate models are underdeveloped or nonexistent, due to the fact that details of the mechanisms leading to nitrous acid (HONO) and nitrogen dioxide (NO2) formation in soil are lacking. This represents a major gap in our understanding of a significant land-atmosphere interaction that prevents us from scaling these processes from the laboratory scale to the ecosystem and global scales. There is a critical need to include these mechanisms into climate models since NOy controls the oxidative capacity of the atmosphere, lifetime of greenhouse gases, and the rate of secondary aerosol formation that directly and indirectly affects climate. The team’s working hypothesis is that soil is an important source of NOy in forests and that NOy soil emissions are derived from the soil microbial community via interactions between chemical intermediates stemming from N-cycling and organic carbon decomposition. To test this hypothesis, we will (1) determine the relative importance of biogenic soil emissions to the overall NOy budget in the hardwood forest environment; and (2) measure biogenic NOy fluxes along a well-characterized gradient of forest composition that varies by tree species and their soil microbial associates.
Proposer: Jonathan Raff, Indiana University