title: Chemical characterization of humic-like substances (HULIS) in PM2.5in Lanzhou, China.
abstract: Evaporative light scattering detection (ELSD) was applied to quantify HULIS (humic-like substances) for the first time in 2012 winter and 2013 summer at an urban site in Lanzhou. Water soluble organic carbon (WSOC), water soluble inorganic ions, and carbonaceous species (OC/EC) were also analyzed. The results show that OM (Organic Matter=OC×1.6, constituting 45.8% to PM2.5) was the most abundant species, followed by SNA (SO42-+NO3-+NH4+, constituting 23.4% to PM2.5). The chemical species were in the order of: OC>EC>SO42->NO3->NH4+>Cl->Ca2+>K+. The annual average concentration of HULIS was 4.70μg/m-3and HULISc (carbon content of HULIS) contributed 6.19% to PM2.5and 45.6% to WSOC, indicating that HULIS was the most important components of WSOC. The concentration of HULIS was 2.14±0.80μg/m3in summer and 7.24±2.77μg/m3in winter, respectively. The concentrations of HULIS were relatively low and stable in summer, while high and varied dramatically in winter. The abundance of HULISc in WSOC shows a more concentrated distribution in Lanzhou, with a range between 0.28-0.57. The ratios of HULIS/K+were 6.25±1.41 and 6.14±1.96 in summer and winter, respectively, suggesting there were other significant sources in addition to biomass burning emissions. HULIS and WSOC exhibited similar seasonal variation and had a strong positive correlation. In addition to the good relationship (0.89) between HULIS and Cl-in winter, the great enhancement of HULIS with significantly high Cl-and relatively low K+in winter indicated that residential coal burning was probably an important HULIS source in winter. Correlation and back trajectory analysis suggested that biomass burning and secondary formation were also important HULIS sources and the contribution of HULIS from dust could be neglected. Adverse meteorological conditions were also important factors for the accumulation of HULIS in winter.
authors.affiliation: Huairou Eco-Environmental Observatory, College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; School of Environment, Tsinghua University, Beijing 100084, China; Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Jihua
authors.initials: J
authors.lastname: Tan
authors.affiliation: Huairou Eco-Environmental Observatory, College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Xiang
authors.affiliation: Huairou Eco-Environmental Observatory, College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Xueming
authors.initials: X
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: Djc74@163.com.
authors.forename: Jingchun
authors.initials: J
authors.lastname: Duan
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Ma
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Kebin
authors.initials: K
authors.lastname: He
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Jianzhen
authors.initials: J
authors.lastname: Yu
authors.affiliation: Institute of Environmental Assessment and Water Research, Jordi Girona 18-26, E-08034 Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Querol
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D006812:Humic Substances / Q000032:analysis*; D052638:Particulate Matter / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D006812:Humic Substances; D052638:Particulate Matter
keywords: HULIS; Haze; Lanzhou; PM(2.5); WSOC