title: Decreasing effect and mechanism of FeSO4 seed particles on secondary organic aerosol in α-pinene photooxidation.
abstract: α-Pinene/NOx and α-pinene/HONO photooxidation experiments at varying humidity were conducted in smog chambers in the presence or absence of FeSO4 seed particles. FeSO4 seed particles decrease SOA mass as long as water was present on the seed particle surface, but FeSO4 seed particles have no decreasing effect on SOA under dryer conditions at 12% relative humidity (RH). The decreasing effect of FeSO4 seed particles on the SOA mass is proposed to be related to oxidation processes in the surface layer of water on the seed particles. Free radicals, including OH, can be formed from catalytic cycling of Fe(2+) and Fe(3+) in the aqueous phase. These radicals can react further with the organic products of α-pinene oxidation on the seed particles. The oxidation may lead to formation of smaller molecules which have higher saturation vapor pressures and favor repartitioning to the gas phase, and therefore, reduces SOA mass.
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Biwu
authors.initials: B
authors.lastname: Chu
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Air Quality Research Division, Environment Canada, Toronto, Ontario, Canada.
authors.forename: Yongchun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Junhua
authors.initials: J
authors.lastname: Li
authors.affiliation: Toyota Central Research and Development Laboratory, Nagakute, Aichi 480-1192, Japan.
authors.forename: Hideto
authors.initials: H
authors.lastname: Takekawa
authors.affiliation: Air Quality Research Division, Environment Canada, Toronto, Ontario, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Liggio
authors.affiliation: Air Quality Research Division, Environment Canada, Toronto, Ontario, Canada.
authors.forename: Shao-Meng
authors.initials: SM
authors.lastname: Li
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Jingkun
authors.initials: J
authors.lastname: Jiang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Jiming
authors.initials: J
authors.lastname: Hao
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: honghe@rcees.ac.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: He
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D000081008:Bicyclic Monoterpenes; D005296:Ferrous Compounds / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D006813:Humidity; D039821:Monoterpenes / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes
chemical_list: D000336:Aerosols; D000081008:Bicyclic Monoterpenes; D005296:Ferrous Compounds; D005740:Gases; D039821:Monoterpenes; C020748:ferrous sulfate; C005451:alpha-pinene
keywords: Decreasing effect; FeSO(4) seed particle; Relative humidity; Secondary organic aerosol; α-Pinene