10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Soil NOx Emissions and Particulate Nitrate Formation in California
Abhishek Dhiman, Anikender Kumar, Maya Almaraz, Ian Faloona, Benjamin Houlton, MICHAEL KLEEMAN, University of California, Davis
Abstract Number: 983 Working Group: Aerosol Modeling
Abstract PM2.5 concentrations in California continue to violate the National Ambient Air Quality Standards designed to protect human health. The highest PM2.5 concentrations occur during winter months with major contributions from particulate ammonium nitrate. Chemical transport models are used to help design efficient emissions control programs to address PM2.5 pollution, but these models have generally failed to predict basecase particulate ammonium nitrate concentrations in recent years. This calls into question the accuracy of future emissions control strategies for PM2.5 in California.
Recent work suggests that soils enriched with nitrogen fertilizers release oxides of nitrogen (NOx) that can play a role in atmospheric chemistry. Here we analyze the effect of soil NOx emissions on winter particulate nitrate formation and summer ozone formation in California. Monthly emissions of soil NOx are estimated based on fertilizer application rates, soil types, soil moisture, and temperature. These emissions are combined with standard emissions inventories provided by the California Air Resources Board. Episodes spanning the years 2000 through 2016 are simulated with and without soil NOx emissions using a regional chemical transport model. Predicted concentrations are compared to measurements to quantify improvements to model performance. Source apportionment routines are used to predict soil NOx contributions to ambient PM2.5 concentrations. Public health impacts are quantified using established epidemiological findings to estimate the potential health effects of soil NOx emissions in California.