Secondary aerosol formation and oxidation capacity in photooxidation in the presence of Al_2O_3 seed particles and SO_2  

作　　者：Biwu Chu Tengyu Liu Xiao Zhang Yongchun Liu Qingxin Ma Jinzhu Ma Hong He Xinming Wang Junhua Li Jiming Hao 

机构地区：[1]State Key Joint Laboratory of Environment Simulation and Pollution Control [2]Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences [3]State Key Laboratory of Organic Geochemistry [4]Guangzhou Institute of Geochemistry, Chinese Academy of Sciences [5]School of Environment, Tsinghua University [6]Nanjing University of Information Science & Technology

出　　处：《Science China Chemistry》2015年第9期1426-1434,共9页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(21407158);the"Strategic Priority Research Program"of the Chinese Academy of Sciences(XDB05010300,XDB05040100,XDB05010200)

摘　　要：To investigate the sensitivity of secondary aerosol formation and oxidation capacity to NOx in homogeneous and heterogeneous reactions, a series of irradiated toluene/NOx/air and ?-pinene/NOx/air experiments were conducted in smog chambers in the absence or presence of Al2O3 seed particles. Various concentrations of NOx and volatile organic compounds(VOCs) were designed to simulate secondary aerosol formation under different scenarios for NOx. Under "VOC-limited" conditions, the increasing NOx concentration suppressed secondary aerosol formation, while the increasing toluene concentration not only contributed to the increase in secondary aerosol formation, but also led to the elevated oxidation degree for the organic aerosol. Sulfate formation was suppressed with the increasing NOx due to a decreased oxidation capacity of the photooxidation system. Secondary organic aerosol(SOA) formation also decreased with the presence of high concentration of NOx, because organo-peroxy radicals(RO2) react with NOx instead of with peroxy radicals(RO2 or HO2), resulting in the formation of volatile organic products. The increasing concentration of NOx enhanced the formation of sulfate, nitrate and SOA under "NOx-limited" conditions, in which the heterogeneous reactions played an important role. In the presence of Al2O3 seed particles, a synergetic promoting effect of mineral dust and NOx on secondary aerosol formation in heterogeneous reactions was observed in the photooxidation. This synergetic effect strengthened the positive relationship between NOx and secondary aerosol formation under "NOx-limited" conditions but weakened or even overturned the negative relationship between NOx and secondary aerosol formation under "VOC-limited" conditions. Sensitivity of secondary aerosol formation to NOx seemed different in homogeneous and heterogeneous reactions, and should be both taken into account in the sensitivity study. The sensitivity of secondary aerosol formation to NOx was further investigated under "winter-like" and NH3-rich cTo investigate the sensitivity of secondary aerosol formation and oxidation capacity to NOx in homogeneous and heterogeneous reactions, a series of irradiated toluene/NOx/air and α-pinene/NOx/air experiments were conducted in smog chambers in the absence or presence of Al2O3 seed particles. Various concentrations of NOx and volatile organic compounds（VOCs） were designed to simulate secondary aerosol formation under different scenarios for NOx. Under ＂VOC-limited＂ conditions, the increasing NOx concentration suppressed secondary aerosol formation, while the increasing toluene concentration not only contributed to the increase in secondary aerosol formation, but also led to the elevated oxidation degree for the organic aerosol. Sulfate formation was suppressed with the increasing NOx due to a decreased oxidation capacity of the photooxidation system. Secondary organic aerosol（SOA） formation also decreased with the presence of high concentration of NOx, because organo-peroxy radicals（RO2） react with NOx instead of with peroxy radicals（RO2 or HO2）, resulting in the formation of volatile organic products. The increasing concentration of NOx enhanced the formation of sulfate, nitrate and SOA under ＂NOx-limited＂ conditions, in which the heterogeneous reactions played an important role. In the presence of Al2O3 seed particles, a synergetic promoting effect of mineral dust and NOx on secondary aerosol formation in heterogeneous reactions was observed in the photooxidation. This synergetic effect strengthened the positive relationship between NOx and secondary aerosol formation under ＂NOx-limited＂ conditions but weakened or even overturned the negative relationship between NOx and secondary aerosol formation under ＂VOC-limited＂ conditions. Sensitivity of secondary aerosol formation to NOx seemed different in homogeneous and heterogeneous reactions, and should be both taken into account in the sensitivity study. The sensitivity of secondary aerosol formation to NOx was further investigated u

关 键 词：secondary aerosol oxidation capacity synergetic promoting effect Al2O3 seed particles sensitivity 

分 类 号：X513[环境科学与工程—环境工程] TU991.2[建筑科学—市政工程]