In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists ...In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.展开更多
基于自主研发的气溶胶消光光谱仪,在安徽省寿县观测站点进行了连续观测,并对2016年5月至12月期间该地区的大气气溶胶光学特性开展了研究。结合不同大气因素分析了观测结果的时间序列变化及日变化规律,对比了消光系数与PM_(2.5)质量浓度...基于自主研发的气溶胶消光光谱仪,在安徽省寿县观测站点进行了连续观测,并对2016年5月至12月期间该地区的大气气溶胶光学特性开展了研究。结合不同大气因素分析了观测结果的时间序列变化及日变化规律,对比了消光系数与PM_(2.5)质量浓度、散射系数的相关性,并探讨了风速风向对于寿县消光系数变化的影响。结果表明:寿县地区大气消光系数时间序列变化与日变化特征明显,且受到不同气象要素的影响。秋季和冬季的大气污染情况较为严重,与其他季节相比,污染天气的天数明显增多;与清洁天气相比,污染天气的消光系数和PM_(2.5)质量浓度、散射系数显著增大。特别在冬季,污染事件频繁。在12月份出现过重度污染天,其24 h PM_(2.5)平均浓度超过150μg·m^(-3),且该月消光系数和PM_(2.5)质量浓度、散射系数均达到观测期间月平均最大值。整个观测期间,从日变化来看,消光系数、PM_(2.5)质量浓度及散射系数均是白天波动较大,午后出现最低值;其中消光系数最大值出现于清晨08:00左右,最小值则出现于下午16:00左右。此外,消光光谱仪测得的气溶胶消光系数与PM_(2.5)质量浓度和散射系数的相关系数分别为0.91和0.83,说明研制的消光光谱仪同其他仪器的测量结果具有很好的一致性。展开更多
Indoor smog chamber experiments have been conducted to investigate the dynamics of sec- ondary organic aerosol （SOA） formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. T...Indoor smog chamber experiments have been conducted to investigate the dynamics of sec- ondary organic aerosol （SOA） formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investi- gated. It was shown that in the presence of high-level seed aerosol and low-level isoprene （typical urban atmospheric conditions）, particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene （typical atmospheric conditions in rural re-gion）, bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.展开更多
Theoretical calculations have been carried out to investigate the possible dissociation channels of isoprene. We focus on the major fragment ions of C5H7＋, C5H5＋, C4H5＋, C3H6＋, C3H5＋, C3H4＋, C3H3＋ and C2H3＋, w...Theoretical calculations have been carried out to investigate the possible dissociation channels of isoprene. We focus on the major fragment ions of C5H7＋, C5H5＋, C4H5＋, C3H6＋, C3H5＋, C3H4＋, C3H3＋ and C2H3＋, which were observed experimentally from the isoprene dissociative photoionization. The energy calculations were performed with the CBS-QB3 model. All the geometries and energies of the fragments, intermediates and transition states involved in the dissociations channels were determined. Finally, the mechanisms of the dissociation pathways were discussed on the comparison of theoretical and experimental results.展开更多
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(KJCX2-YW-N24,KZCX2-YW-Q02-03)National Natural Science Foundation of China(40925016,40830101)~~
基金This work was supported by the Natural Science Foundation of Anhui Province, China （No.1208085MD59）, the National Natural Science Foundation of China （No.U1232209, No.41175121, and No.21307137）, the Presidential Foundation of Hefei Institutes of Physical Science, Chinese Academy of Sciences, China （No.YZJJ201302）, and the Knowledge Innovation Foundation of the Chinese Academy of Sciences （No.KJCX2-YW-N24）.
文摘In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.
文摘基于自主研发的气溶胶消光光谱仪,在安徽省寿县观测站点进行了连续观测,并对2016年5月至12月期间该地区的大气气溶胶光学特性开展了研究。结合不同大气因素分析了观测结果的时间序列变化及日变化规律,对比了消光系数与PM_(2.5)质量浓度、散射系数的相关性,并探讨了风速风向对于寿县消光系数变化的影响。结果表明:寿县地区大气消光系数时间序列变化与日变化特征明显,且受到不同气象要素的影响。秋季和冬季的大气污染情况较为严重,与其他季节相比,污染天气的天数明显增多;与清洁天气相比,污染天气的消光系数和PM_(2.5)质量浓度、散射系数显著增大。特别在冬季,污染事件频繁。在12月份出现过重度污染天,其24 h PM_(2.5)平均浓度超过150μg·m^(-3),且该月消光系数和PM_(2.5)质量浓度、散射系数均达到观测期间月平均最大值。整个观测期间,从日变化来看,消光系数、PM_(2.5)质量浓度及散射系数均是白天波动较大,午后出现最低值;其中消光系数最大值出现于清晨08:00左右,最小值则出现于下午16:00左右。此外,消光光谱仪测得的气溶胶消光系数与PM_(2.5)质量浓度和散射系数的相关系数分别为0.91和0.83,说明研制的消光光谱仪同其他仪器的测量结果具有很好的一致性。
文摘Indoor smog chamber experiments have been conducted to investigate the dynamics of sec- ondary organic aerosol （SOA） formation from OH-initiated photo-oxidation of isoprene in the presence of organic seed aerosol. The dependence of the size distributions of SOA on both the level of pre-existing particles generated in situ from the photo-oxidation of trace hydrocarbons of indoor atmosphere and the concentration of precursor, has been investi- gated. It was shown that in the presence of high-level seed aerosol and low-level isoprene （typical urban atmospheric conditions）, particle growth due to condensation of secondary organic products on pre-existing particles dominated; while in the presence of low-level seed aerosol and comparatively high-level isoprene （typical atmospheric conditions in rural re-gion）, bimodal structures appeared in the size distributions of SOA, which corresponded to new particle formation resulting from homogeneous nucleation and particle growth due to condensation of secondary organic products on the per-existing particles respectively. The effects of concentrations of organic seed particles on SOA were also investigated. The particle size distributions evolutions as well as the corresponding formation rates of new particles in different conditions were also estimated.
基金This work was supported by the National Natural Science Foundation of China （No.91544228, No.21307137, No.41575125, No.41375127, No.U1232209） and the Outstanding Youth Science Foundation of Fujian Province of China （No.2015J06009）.
文摘Theoretical calculations have been carried out to investigate the possible dissociation channels of isoprene. We focus on the major fragment ions of C5H7＋, C5H5＋, C4H5＋, C3H6＋, C3H5＋, C3H4＋, C3H3＋ and C2H3＋, which were observed experimentally from the isoprene dissociative photoionization. The energy calculations were performed with the CBS-QB3 model. All the geometries and energies of the fragments, intermediates and transition states involved in the dissociations channels were determined. Finally, the mechanisms of the dissociation pathways were discussed on the comparison of theoretical and experimental results.
