TY - JOUR
T1 - Optical properties, source apportionment and redox activity of humic-like substances (HULIS) in airborne fine particulates in Hong Kong
AU - Ma, Yiqiu
AU - Cheng, Yubo
AU - Qiu, Xinghua
AU - Cao, Gang
AU - Kuang, Binyu
AU - Yu, Jian Zhen
AU - Hu, Di
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China (NSFC 21477102), the General Research Fund of Hong Kong Research Grant Council (12328216, 12304215, 12300914 and 201212), Science, Technology and Innovation Commission of Shenzhen Municipality (JCYJ 20160531193751295) and the Faculty Research Grant from Hong Kong Baptist University (FRG2/16-17/041).
Funding Information:
t his work was supported by the National Natural Science Foundation of China ( NSFC 21477102 ), the General Research Fund of Hong Kong Research Grant Council ( 12328216 , 12304215 , 12300914 and 201212 ), Science, Technology and Innovation Commission of Shenzhen Municipality ( JCYJ 20160531193751295 ) and the Faculty Research Grant from Hong Kong Baptist University ( FRG2/16-17/041 ). The authors thank the Environmental Central Facility (ENVF) in Hong Kong University of Science and Technology (HKUST) for real-time environmental and air quality data ( http://envf.ust.hk/dataview/gts/current/ ).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - 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 (DTT) 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 DTT 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 HULIS was also investigated by normalizing the DTT 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.
AB - 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 (DTT) 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 DTT 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 HULIS was also investigated by normalizing the DTT 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.
KW - Hong Kong
KW - Optical properties
KW - Oxidative potential
KW - PM-bound HULIS
KW - Source apportionment
UR - http://www.scopus.com/inward/record.url?scp=85072260141&partnerID=8YFLogxK
U2 - 10.1016/j.envpol.2019.113087
DO - 10.1016/j.envpol.2019.113087
M3 - Journal article
C2 - 31541815
AN - SCOPUS:85072260141
SN - 0269-7491
VL - 255, Part 1
JO - Environmental Pollution
JF - Environmental Pollution
M1 - 113087
ER -