Oxidative potential of ambient PM2.5 in the coastal cities of the Bohai Sea, northern China: Seasonal variation and source apportionment

WeiJian Liu; YunSong Xu; WenXin Liu; QingYang Liu; ShuangYu Yu; Yang Liu; Xin Wang; Shu Tao

doi:10.1016/j.envpol.2018.01.116

Oxidative potential of ambient PM_2.5 in the coastal cities of the Bohai Sea, northern China: Seasonal variation and source apportionment

Environ Pollut. 2018 May:236:514-528. doi: 10.1016/j.envpol.2018.01.116.

Authors

WeiJian Liu¹, YunSong Xu¹, WenXin Liu², QingYang Liu³, ShuangYu Yu¹, Yang Liu¹, Xin Wang¹, Shu Tao¹

Affiliations

¹ Key Laboratory for Earth Surface and Processes, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.
² Key Laboratory for Earth Surface and Processes, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China. Electronic address: wxliu@urban.pku.edu.cn.
³ Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China. Electronic address: qyliu@njfu.edu.cn.

PMID: 29428706
DOI: 10.1016/j.envpol.2018.01.116

Abstract

Emissions of air pollutants from primary and secondary sources in China are considerably higher than those in developed countries, and exposure to air pollution is main risk of public health. Identifying specific particulate matter (PM) compositions and sources are essential for policy makers to propose effective control measures for pollutant emissions. Ambient PM_2.5 samples covered a whole year were collected from three coastal cities of the Bohai Sea. Oxidative potential (OP) was selected as the indicator to characterize associated PM compositions and sources most responsible for adverse impacts on human health. Positive matrix factorization (PMF) and multiple linear regression (MLR) were employed to estimate correlations of PM_2.5 sources with OP. The volume- and mass-based dithiothreitol (DTT_v and DTT_m) activities of PM_2.5 were significantly higher in local winter or autumn (p < 0.01). Spatial and seasonal variations in DTT_v and DTT_m were much larger than mass concentrations of PM_2.5, indicated specific chemical components are responsible for PM_2.5 derived OP. Strong correlations (r > 0.700, p < 0.01) were found between DTT activity and water-soluble organic carbon (WSOC) and some transition metals. Using PMF, source fractions of PM_2.5 were resolved as secondary source, traffic source, biomass burning, sea spray and urban dust, industry, coal combustion, and mineral dust. Further quantified by MLR, coal combustion, biomass burning, secondary sources, industry, and traffic source were dominant contributors to the water-soluble DTT_v activity. Our results also suggested large differences in seasonal contributions of different sources to DTT_v variability. A higher contribution of DTT_v was derived from coal combustion during the local heating period. Secondary sources exhibited a greater fraction of DTT_v in summer, when there was stronger solar radiation. Traffic sources exhibited a prevailing contribution in summer, and industry contributed larger proportions in spring and winter. Future abatement priority of air pollution should reduce the sources contributing to OP of PM_2.5.

Keywords: Coastal cities on the Bohai Sea; Oxidative potential; PM(2.5); Seasonal variation; Source apportionment.

MeSH terms

Air Pollutants / analysis*
China
Cities
Dust / analysis
Environmental Monitoring / methods*
Humans
Oceans and Seas
Particle Size
Particulate Matter / analysis*
Reactive Oxygen Species / analysis*
Seasons
Vehicle Emissions / analysis*

Substances

Air Pollutants
Dust
Particulate Matter
Reactive Oxygen Species
Vehicle Emissions