Open AccessA comparison of isoprene nitrate concentrations at two forest‐impacted sites
Author(s) -
Grossenbacher John W.,
Barket Jr. Dennis J.,
Shepson Paul B.,
Carroll Mary Anne,
Olszyna Kenneth,
Apel Eric
Publication year - 2004
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2003jd003966
Subject(s) - isoprene , nitrate , environmental chemistry , chemistry , atmospheric chemistry , environmental science , ozone , organic chemistry , copolymer , polymer
We report measurements of isoprene nitrates as part of the Southern Oxidants Study during the summer of 1999 at a rural/forest site in Tennessee. Average midday concentrations of the isoprene nitrates were ∼115 ppt. This is ∼10 times greater than the previously reported concentrations during the Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET) study in 1998 at Pellston, Michigan, representing as much as 5% of NO y . Here we investigate the possible factors for the large difference in concentrations. To investigate the role of the NO x concentration on the isoprene nitrate production chemistry at the two sites, [OH] was calculated using a simple steady state model. The results of this calculation help explain the difference in magnitude of the isoprene nitrate concentrations between the two field sites in terms of the [NO x ]‐dependent behavior of the OH‐initiated oxidation of isoprene and the subsequent isoprene peroxy radical reactions with NO x . However, it is also clear that the large apparent differences in the photochemical ages of the air masses sampled at the two sites significantly impacted the observed concentrations.