Atmospheric production of oxalic acid/oxalate and nitric acid/nitrate in the Tampa Bay airshed: Parallel pathways

作者：Martinelango P Kalyani; Dasgupta Purnendu K^*; Al Horr Rida S

来源：Atmospheric Environment, 2007, 41(20): 4258-4269.

DOI：10.1016/j.atmosenv.2006.05.085

• oxalate
• oxalic acid
• BRACE
• nitrogen deposition
• photochemical production

Oxalic acid is the dominant dicarboxylic acid (DCA), and it constitutes up to 50% of total atmospheric DCAs, especially in non-urban and marine atmospheres. A significant amount of particulate H(2)Ox/oxalate (Ox) occurred in the coarse particle fraction of a dichotomous sampler, the ratio of oxalate concentrations in the PM10 to PM2.5 fractions ranged from 1 to 2, with mean + sd being 1.4 + 0.2. These results suggest that oxalate does not solely originate in the gas phase and condense into particles. Gaseous H(2)Ox concentrations are much lower than particulate Ox concentrations and are well correlated with HNO3, HCHO, and O-3, supporting a photochemical origin. Of special relevance to the Bay Region Atmospheric Chemistry Experiment (BRACE) is the extent of nitrogen deposition in the Tampa Bay estuary. Hydroxyl radical is primarily responsible for the conversion of NO2 to HNO3, the latter being much more easily deposited. Hydroxyl radical is also responsible for the aqueous phase formation of oxalic acid from alkenes. Hence, we propose that an estimate of -OH can be obtained from H(2)Ox/Ox production rate and we accordingly show that the product of total oxalate concentration and NO2 concentration approximately predicts the total nitrate concentration during the same period.

• 出版日期2007-6