期刊
ATMOSPHERIC ENVIRONMENT
卷 226, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.atmosenv.2020.117407
关键词
Unresolved complex mixtures (UCM); Gas/particle partitioning; Source apportionment; Vehicle exhaust; Biomass burning; Ship emission
资金
- National Key Research and Development Program [2016YFC0202204/2017YFC0212802]
- Natural Science Foundation of China [41571130031/41530641]
- Chinese Academy of Sciences [QYZDJ-SSW-DQC032]
- Guangdong Science and Technology Department [2017BT01Z134/2016TQ03Z993]
- Guangzhou Science Technology and Innovation Commission [201607020002]
- Youth Innovation Promotion Association, CAS [2017406]
Unresolved complex mixture (UCM) accounts for a substantial fraction of particulate organic matters and plays an important role in forming secondary organic aerosol (SOA), yet their abundance, sources and atmospheric processes are not well understood. In this study, filter-based ambient PM2.5 samples were collected concourrently at an urban site and a rural site in the Pearl River Delta (PRD) region, south China, to characterize semi-volatile UCM. Dust, urban tunnel exhaust, ship exhaust and biomass burning samples were also collected to characterize UCM from typical primary emission sources. No obvious UCM humps were found in total ion chromatograms (TIC) of the PM2.5 samples collected during July-October, while the determined UCM reached 6.51 +/- 4.92 mu g/m(3) at the urban site and 6.75 +/- 4.78 mu g/m(3) at the rural site during November-May, accounting for similar to 9% of PM2.5 mass at both sites. The missing UCM humps in the hot months were due to much large fraction of these semi-volatiles partitioning to gas phase and their much faster atmospheric oxidation. In addition, the lower organic matter (OM) was also a non-negligible factor contributing to less particulate UCM in summer. Five major sources for PM2.5-bound UCM were identified by positive matrix factorization (PMF) involving organic and inorganic molecular source tracers. Vehicle exhaust accounted for 44.4% and 30.3% of UCM at the urban and the rural site, respectively. Biomass burning contributed more to UCM at the rural site (28.0%) than at the urban site (19.2%). Ship emission was found to contribute substantially to UCM (28.9% at the urban and 17.3% at the rural site) in the PRD harbor megacity. Coal combustion and dust altogether contributed much less at the urban site (7.5%) than at the rural site (24.4%).
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