Observations of ozone formation in power plant plumes and implications forozone control strategies

Data taken in aircraft transects of emissions plumes from rural U.S. coal-f ired power plants were used to confirm and quantify the nonlinear dependenc e of tropospheric ozone formation on plume NOx (NO plus NO2) concentration, which is determined by plant NOx emission rate and atmospheric dispersion. The ambient availability of reactive volatile organic compounds, principal ly biogenic isoprene, was also found to modulate ozone production rate and yield in these rural plumes. Differences of a factor of 2 or greater in plu me ozone formation rates and yields as a function of NOx and volatile organ ic compound concentrations were consistently observed. These large differen ces suggest that consideration of power plant NOx emission rates and geogra phic locations in current and future U.S. ozone control strategies could su bstantially enhance the efficacy of NOx reductions from these sources.