1 research outputs found
Ambient Gas-Particle Partitioning of Tracers for Biogenic Oxidation
Exchange
of atmospheric organic compounds between gas and particle
phases is important in the production and chemistry of particle-phase
mass but is poorly understood due to a lack of simultaneous measurements
in both phases of individual compounds. Measurements of particle-
and gas-phase organic compounds are reported here for the southeastern
United States and central Amazonia. Polyols formed from isoprene oxidation
contribute 8% and 15% on average to particle-phase organic mass at
these sites but are also observed to have substantial gas-phase concentrations
contrary to many models that treat these compounds as nonvolatile.
The results of the present study show that the gas-particle partitioning
of approximately 100 known and newly observed oxidation products is
not well explained by environmental factors (e.g., temperature). Compounds
having high vapor pressures have higher particle fractions than expected
from absorptive equilibrium partitioning models. These observations
support the conclusion that many commonly measured biogenic oxidation
products may be bound in low-volatility mass (e.g., accretion products,
inorganic–organic adducts) that decomposes to individual compounds
on analysis. However, the nature and extent of any such bonding remains
uncertain. Similar conclusions are reach for both study locations,
and average particle fractions for a given compound are consistent
within ∼25% across measurement sites