期刊
ENVIRONMENTAL POLLUTION
卷 255, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2019.113087
关键词
PM2.5-bound HULIS; Optical properties; Oxidative potential; Source apportionment; Hong Kong
资金
- National Natural Science Foundation of China [NSFC 21477102]
- General Research Fund of Hong Kong Research Grant Council [12328216, 12304215, 12300914, 201212]
- Science, Technology and Innovation Commission of Shenzhen Municipality [JCYJ 20160531193751295]
- Faculty Research Grant from Hong Kong Baptist University [FRG2/16-17/041]
Humic-like substances (HULIS) account for a considerable fraction of water-soluble organic matter (WSOM) in ambient fine particulates (PM2,5) over the world. However, systemic studies regarding the chemical characteristics, sources and redox activity of HULIS are still limited. In this study, the mass concentration, optical properties, and reactive oxygen species (ROS)-generation potential of HULIS were investigated in PM2.5 samples collected in Hong Kong during 2011-2012, and they all showed higher levels on days under regional pollution than on days under long range transport (LRT) pollution and local emissions. Positive matrix factorization (PMF) analysis was conducted regarding the mass concentration and dithiothreitol (DTF) activity of HULIS. Four primary sources (i.e. marine vessels, industrial exhaust, biomass burning, and vehicle emissions), and two secondary sources (i.e. secondary organic aerosol formation and secondary sulfate) were identified. Most sources showed higher contributions to both the mass concentration and DTT activity of HULIS on regional days than on LRT and local days, except that marine vessels had a higher contribution on local days than the other two synoptic conditions. Secondary processes were the major contributor to HULIS (54.9%) throughout the year, followed by biomass burning (27.4%) and industrial exhaust (14.7%). As for the DTF activity of HULIS, biomass burning (62.9%) and secondary processes (25.4%) were found to be the top two contributors. Intrinsic ROS-generation potential of HULLS was also investigated by normalizing the OTT activity by HULIS mass in each source. HULIS from biomass burning were the most DTT-active, followed by marine vessels; while HULIS formed through secondary processes were the least DTT-active. For the optical properties of HULIS, multiple linear regression model was adopted to evaluate the contributions of various sources to the light absorbing ability of HULIS. Biomass burning was found to be the only source significantly associated with the light absorbing property of HULIS. (C) 2019 Elsevier Ltd. All rights reserved.
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