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Atmospheric Observations of Nitrogen: Linking Regulatory Applications and Science across Atmospheric, Terrestrial and Aquatic Media

Rich Scheffe1, Adam Reff2, Eric Edgerton3, Joe Sickles4, Robin Dennis4, Gary Lear1, John Walker4, Rob Pinder4, John Ray5, Norm Possiel1 and Jeff Brook6

Observations of atmospheric nitrogen support environmental management and scientific research efforts bridging ambient air and terrestrial and aquatic environments. Atmospheric nitrogen influences ecosystem acidification and nutrient enrichment and is a principal precursor driving human health effects associated with ozone and fine particle pollution collectively representing some our most prominent environmental issues over the last two decades. Indeed, emissions of oxides of nitrogen have been the central backbone of national level air pollution emission mitigation regulations over the last decade. Prospectively, the relative importance of nitrogen is escalating as air pollution management gradually takes on a multiple pollutant, multiple media framework recognizing the variety of linkages across physical-chemical processes throughout the source to effects continuum. Additional complexity will arise from future energy driven policies that likely will alter atmospheric nitrogen composition. Despite the relative importance of nitrogen and considerable resources allocated to controlling nitrogen emissions, existing nitrogen observation networks are severely challenged with respect to the relevancy of species measured and the associated spatial and temporal coverage of sample collection. Examples of these shortcomings include the reliance on satellite based total column nitrogen dioxide observations to confirm the atmospheric response to the NOx SIP CALL reductions from 2000 2005 and the lack of virtually any deployed instruments that measure nitrogen dioxide, despite the promulgation of a tighter nitrogen dioxide air quality standard in 2010. As we accelerate efforts to develop standards that protect aquatic and terrestrial ecosystems, we are forced to proceed without an observational basis for characterizing either oxidized or reduced forms of nitrogen. This presentation will use a combination of measurements and air quality model results to guide the development of a responsive observational network of key nitrogen species in addressing multiple environmental issues.

1U.S. EPA-OAR
2U.S. EPA-OAQPS
3Atmospheric Research Analysis
4U.S. EPA-ORD
5 National Park Service
6 Environment Canada