Hydrogen peroxide dry deposition lifetime determined from observed loss rates in a power plant plume

Hydrogen peroxide measurements made aboard the NOAA WP‐3D aircraft in the summer of 1995 as part of the Southern Oxidants Study revealed loss of hydrogen peroxide within fossil fuel power plant plumes and the Nashville urban plume. On July 7 the Cumberland power plant plume was intercepted at five different downwind distances. H 2 O 2 mixing ratios within the plume decreased with increasing distance from the plant. Conversely, ozone mixing ratios increased. The H 2 O 2 loss was likely a result of the lowered rate of formation due to suppression of HO 2 radical concentrations in the high NO x environment and subsequent removal of H 2 O 2 by photolysis, reaction with HO, and dry deposition. From steady state model estimates of the chemical loss rates in the plume and an analytical approximation of the influx of H 2 O 2 into the plume center due to horizontal dispersion, a simple budget for H 2 O 2 was formulated, from which a dry deposition lifetime of 19 hours ±55% was inferred.