Chemical Contributions to the Forest-Atmosphere Exchange of Reactive NitrogenEPA Grant Number: F08B10294
Title: Chemical Contributions to the Forest-Atmosphere Exchange of Reactive Nitrogen
Investigators: Wolfe, Glenn
Institution: University of Washington
EPA Project Officer: Michaud, Jayne
Project Period: January 1, 2008 through December 31, 2008
RFA: STAR Graduate Fellowships (2009) RFA Text | Recipients Lists
Research Category: Academic Fellowships
The biosphere-atmosphere system is a complex chemical reactor, where forest emissions, surface deposition, anthropogenic pollution and photochemistry interact to determine regional atmospheric composition and ecosystem vitality. My research utilizes a combination of in-situ observations and numerical modeling to develop a comprehensive picture of the processes contributing to the forest-atmosphere exchange of reactive trace gases, with particular attention to a significant class of reactive nitrogen known as acyl peroxy nitrates (APNs).
As temporary reservoirs of nitrogen oxides (NOx), APNs can alter the regional impacts of urban emissions on ozone and aerosol formation. During the Biosphere Effects on Aerosol and Photochemistry Experiment (BEARPEX), a collaborative field campaign taking place in the Sierra Nevada foothills during summer 2007 and 2009, I deployed a state-of-the-art thermal dissociation-chemical ionization mass spectrometer (TD-CIMS) to make in-situ measurements of APN vertical concentration profiles and eddy covariance fluxes within a Ponderosa pine forest.
Results from this study suggest that up to 20% of the total nitrogen deposition in the Sierra Nevada may be unaccounted for in current models. Correctly partitioning the measured flux between physical deposition and chemistry is key to maximizing the predictive capability of atmospheric chemistry models and assessing anthropogenic impacts on air quality, biosphere health and carbon cycling.