HR: 1330h
AN: A42A-0747    [PDF]
TI: Prediction of Coarse Particle Nitrate From Fine Particle Measurements in a Coastal Environment
AU: * Campbell, S W
EM: campbell@eng.usf.edu
AF: University of South Florida, College of Engineering 4202 E. Fowler Ave., Tampa, FL 33620 United States
AU: Evans, M C
EM: meevans@hsc.usf.edu
AF: University of South Florida, College of Public Health 13201 Bruce B. Downs Blvd., Tampa, FL 33612 United States
AU: Poor, N D
EM: npoor@hsc.usf.edu
AF: University of South Florida, College of Public Health 13201 Bruce B. Downs Blvd., Tampa, FL 33612 United States
AB: Nutrient induced algal growth is one cause of decreased seagrass in the Tampa Bay Estuary. This influx of nutrients arises from the presence of fixed nitrogen in various flows and discharges to the estuary and from atmospheric deposition. One of the goals of BRACE (Bay Regional Atmospheric Chemistry Experiment) is to obtain improved estimates of the atmospheric nitrogen deposition to Tampa Bay. Previous estimates of atmospheric dry deposition of nitrogen to Tampa Bay have been based on Annular Denuder System (ADS) measurements of gaseous nitric acid and ammonia and fine particle (PM2.5) nitrate and ammonium, which extend back to 1996. However, recent coarse particle measurements indicate that, while ammonium primarily exists in fine particles, nitrate is preferentially found in the coarse fraction. The goal of this study is to examine whether the historical data for fine particle nitrate can be used to predict the amount of nitrate in the coarse fraction so as to obtain a more accurate estimate of dry particle deposition of nitrate to the Tampa Bay Estuary. Specifically, it is shown that averaged nitrate distributions obtained from recent micro-orifice impactor data can be used to predict the coarse to fine ratios observed for dichotomous samplers and the fine particle concentrations obtained from the Annular Denuder System. This provides some confidence that the impactor results may be used in conjunction with earlier fine particle data to obtain an estimate of coarse particle nitrate concentrations, and therefore an improved estimate of nitrate flux to the estuary.
DE: 0305 Aerosols and particles (0345, 4801)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting