Amaximumlimonene concentration about 550 μg/m3 (99 ppb) was
measured within the first 30 min upon application of KCA at the low
ozone test concentration (Fig. 1a). This dropped to 350 μg/m3
(63 ppb) at the high ozone test concentration, which indicates
fast ozonolysis and inter alia condensation of VOCs on generated SOA
(Figs. 1b and 2b). Likewise, the observed difference in 1-(2-
butoxyethoxy) ethanol concentration maxima between low and high
ozone test conditions may be explained by condensation on SOA. A
difference in concentration maxima was also observed for glycol and
glycol ethers in PIAF (see below). A reduction of dihydromyrcenol to
about one third at the high ozone test concentration was observed
relative to the low ozone test condition.
At high ozone test concentration, both formaldehyde and acetaldehyde
increased fast for the first 100 min (Fig. 1b). Hereafter, they
decreased in line with the consumption of limonene. The high ozone
test concentration resulted in poly-oxygenates with peak concentrations
of about 17 and 7 μg/m3, respectively, for IPOH and 6-MHO, key
oxidation products of limonene (Atkinson and Arey, 2003; Calogirou
et al., 1999) (Fig. 1c). Other poly-oxygenates, 4-AMCH and 4-OPA,
only reached peak concentrations of less than 3 μg/m3. No polyoxygenated
compoundswere observed at the lowozone test concentration;
however, some formaldehyde and acetaldehyde were emitted
from the KCA. The ozone concentration decreased three-fold from
about 55 ppb to a minimum of 14 ppb within the first 40 min in the
high ozone test concentration, while a decrease from about 10 ppb
to b 5 ppb was observed in the case of the low ozone test concentration
(Fig. 1d).
Amaximumlimonene concentration about 550 μg/m3 (99 ppb) wasmeasured within the first 30 min upon application of KCA at the lowozone test concentration (Fig. 1a). This dropped to 350 μg/m3(63 ppb) at the high ozone test concentration, which indicatesfast ozonolysis and inter alia condensation of VOCs on generated SOA(Figs. 1b and 2b). Likewise, the observed difference in 1-(2-butoxyethoxy) ethanol concentration maxima between low and highozone test conditions may be explained by condensation on SOA. Adifference in concentration maxima was also observed for glycol andglycol ethers in PIAF (see below). A reduction of dihydromyrcenol toabout one third at the high ozone test concentration was observedrelative to the low ozone test condition.At high ozone test concentration, both formaldehyde and acetaldehydeincreased fast for the first 100 min (Fig. 1b). Hereafter, theydecreased in line with the consumption of limonene. The high ozonetest concentration resulted in poly-oxygenates with peak concentrationsof about 17 and 7 μg/m3, respectively, for IPOH and 6-MHO, keyoxidation products of limonene (Atkinson and Arey, 2003; Calogirouet al., 1999) (Fig. 1c). Other poly-oxygenates, 4-AMCH and 4-OPA,only reached peak concentrations of less than 3 μg/m3. No polyoxygenatedcompoundswere observed at the lowozone test concentration;however, some formaldehyde and acetaldehyde were emittedfrom the KCA. The ozone concentration decreased three-fold fromabout 55 ppb to a minimum of 14 ppb within the first 40 min in thehigh ozone test concentration, while a decrease from about 10 ppbto b 5 ppb was observed in the case of the low ozone test concentration(Fig. 1d).
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