This proposal is focused on the role of biogenic hydrocarbons in the removal of atmospheric nitrogen oxides (NOx). The oxidation of volatile organic carbon compounds (VOC's) yields organic peroxy radicals, which can react with NO to form stable organic nitrates. For example, isoprene can react to produce isoprene nitrates, which are believed to be an important sink for NOx. Organic nitrates derived from biogenic VOC's, including isoprene nitrate, have never been measured in ambient air. This proposal involves: 1) development of new membrane inlet quadrupole ion trap methods to detect atmospheric nitrates, 2) field measurements of isoprene nitrates in Northern Michigan as part of the PROPHET study, and 3) laboratory measurement of the yields of organic nitrates from aromatic hydrocarbons, terpenes, and oxygenated VOC's. The results of this research will be utilized to develop a better understanding of the influence of forests and associated biogenic emissions on tropospheric ozone.
