Abstract
Abstract. Secondary organic aerosols (SOA) derived from isoprene, pinene and caryophyllene were determined for PM10 and size-segregated (9-stages) aerosols collected at the summit (2060 m a.s.l.) of Mt. Hua, central China during the summer of 2009. Estimated concentrations of isoprene, α-/β-pinene and β-caryophyllene derived secondary organic carbon (SOC) are 81 ± 53, 29 ± 14 and 98 ± 53 ng m−3, accounting for 2.7 ± 1.0%, 0.8 ± 0.2% and 2.1 ± 1.0% of OC, respectively. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature (R=0.57–0.90). However, a decreasing trend of BSOA concentration with an increase in relative humidity (RH) was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. There was no significant correlation observed for the BSOA products and anthropogenic parameters (e.g. EC, SO42− and NO4−). Size distribution measurements showed that most of the determined BSOA are formed in the aerosol phase and enriched in the fine mode (<2.1 μm) except for cis-pinonic acid, which is formed in the gas phase and subsequently partitioned into aerosol phase and thus presents a bimodal pattern with a small peak in the fine mode and a large peak in the coarse mode (>2.1 μm).
Highlights
Volatile organic compounds (VOCs) produced from the biosphere have a substantial impact on the atmospheric chemistry
biogenic secondary organic aerosols (BSOA) derived from isoprene, pinene and sesquiterpene were determined for PM10 and size-resolved aerosols collected at the mountaintop of Mt
Backward trajectories analysis showed that most the BSOA tracers were present at higher concentrations in the samples from the southerly than those from the easterly and northerly, indicating higher BVOC emissions and/or more BSOA production
Summary
Volatile organic compounds (VOCs) produced from the biosphere have a substantial impact on the atmospheric chemistry. Biogenic volatile organic compounds (BVOCs, 1150 Tg yr−1), mostly consisting of isoprene, monoterpenes (such as α-/β-pinene) and sesquiterpenes (such as β-caryophyllene), are one order of magnitude more abundant than anthropogenic VOCs (Guenther et al, 2006). 2.2 Sample extraction, derivatization and GC/MS 3-methyl-2,3,4-trihydoxy-1-butane; 7. 3-hydorxyglutaric acid; relationship with temperature and relative humidity. 2.1 Sample collection der ultrasonication (15 min each, repeated three times). The sample was injected in a splitless mode made in China) at an airflow rate of 100 L min−1, while the at an injector temperature of 280◦, and scanned from 50 size-segregated samples were collected using an Andersen 9- to 650 Daltons using electron impact (EI) mode at 70 eV. Photochemical product of monoterpene 148 147 (Eddingsaas et al, 2012)
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