Correlation of Ozone and Meteorology with Hydrogen Peroxide in Urban and Rural Regions of North Carolina

Abstract

Gas-phase hydrogen peroxide (H2O2) and ozone (O3) along With other trace gases and meteorology were monitored in two distinct regimes of high- and low-NOx (urban and rural) areas in North Carolina during the summer of 1991 as part of the Southern Oxidants Study (SOS). Gas-phase hydrogen peroxide concentrations ranged from less than 0.05 to about 1.0 ppbv and from less than 0.05 to 2.0 ppbv at the urban and rural sites, respectively. A clear diurnal trend was observed at both locations, though at the urban site the H2O2 profile lagged the ozone profile by 2?3 h. At the rural site, high H2O2 concentrations were observed on certain nights. The various physical, chemical, and meteorological parameters affecting H2O2 concentrations were examined using observational-based statistical analysis. It was found that in the urban air, H2O2 concentrations increased with increasing temperature, solar radiation, and ozone concentrations but decreased with increasing NOx, carbon monoxide, and relative humidity. In the rural air, hydrogen peroxide concentrations were also found to be affected in a similar way. The results of a multivariate statistical analysis indicates that the gas-phase H2O2 concentration observed at the sites is dependent on the atmospheric chemistry and the dynamical characteristics of the sites.