Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign （PRD2004, October 2004） in southeastern C...Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign （PRD2004, October 2004） in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOx, 03, CO, non-methane hydrocarbon （NMHC） and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 × 10^7 to 2.17 × 10^8 molecules cm^-3, the corresponding source rate via reaction of OH and SO2 range between 2.37 × 10^6 and 1.16 × 10^7 molecules cm^-3 s^-1. Nucleation mode growth rate was derived from size spectral evolution during the events to be 6.8-13.8 nm h^-1. Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 × 10^8 to 2.80 × 10^8 molecules cm^-3 with corresponding source rate between 7.26 × 10^6 and 1.64 × 10^7 molecules cm^-3 s^-1. Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.展开更多
A petroleum middle distillate, known as fog oil (FO), has been used in the United military battlefield to create obscurant smoke screens. During studies on the feasibility of replacing FO with relatively environmental...A petroleum middle distillate, known as fog oil (FO), has been used in the United military battlefield to create obscurant smoke screens. During studies on the feasibility of replacing FO with relatively environmentally benign natural oil esters, with similar flow properties, such as methyl soyate (MS), it was observed that FO and MS aerosols and vapors were lethal to Salmonella typhimurium strains (Ames strains used to test for mutagenic activity in the Modified Ames Assay) even after very short exposures. It was further shown that vapors produced from the vegetable oil esters under certain conditions exhibited antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria. In this study, we examined the antimicrobial properties of volatile organic compounds detected in vegetable oil ester vapors. The experiments involved introduction of a known amount of specific compounds present in oil smoke vaors, individually and in combination, into an exposure chamber containing nutrient agar petri dishes inoculated with Salmonella typhimurium. Petri dishes were removed from the chamber after varied exposure periods to determine survival of the bacteria. The results of the experiments showed that individual compounds exhibited antimicrobial activity but lower than the vapors produced during thermal aerosol generation process suggesting the antimicrobial activity of the vapors is likely a synergistic activity of multiple components of the vapors.展开更多
The canopy stomatal movement, a plant physiological process, generally occurs within leaves but its influence on exchange of CO2, water vapor, and sensible heat fluxes between atmosphere and terrestrial ecosystem. Man...The canopy stomatal movement, a plant physiological process, generally occurs within leaves but its influence on exchange of CO2, water vapor, and sensible heat fluxes between atmosphere and terrestrial ecosystem. Many studies have documented that the interaction between leaf photosynthesis and canopy stomatal conductance is obvious. Thus, information on stomatal conductance is valuable in climate and ecosystem models. In current study, a newly developed model was adopted to calculate canopy stomatal conductance of winter wheat in Huang-Huai-Hai (H-H-H) Plain of China (31.5 - 42.7°N, 110.0 - 123.0°E). The remote sensing information from NOAA-AVHRR and meteorological observed data were used to estimate regional scale stomatal conductance distribution. Canopy stomatal conductance distribution pattern of winter wheat on March 18, 1997 was also presented. The developed canopy stomatal conductance model might be used to estimate canopy stomatal conductance in land surface schemes and seems can be acted as a boundary condition in regional climatic model runs.展开更多
基金China National Basic Research and Development Program （Grant Nos. 2002CB410801, 2002CB211605） National Natural Science Foundation of China （Grant No. 40405025）.
文摘Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign （PRD2004, October 2004） in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOx, 03, CO, non-methane hydrocarbon （NMHC） and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 × 10^7 to 2.17 × 10^8 molecules cm^-3, the corresponding source rate via reaction of OH and SO2 range between 2.37 × 10^6 and 1.16 × 10^7 molecules cm^-3 s^-1. Nucleation mode growth rate was derived from size spectral evolution during the events to be 6.8-13.8 nm h^-1. Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 × 10^8 to 2.80 × 10^8 molecules cm^-3 with corresponding source rate between 7.26 × 10^6 and 1.64 × 10^7 molecules cm^-3 s^-1. Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.
文摘A petroleum middle distillate, known as fog oil (FO), has been used in the United military battlefield to create obscurant smoke screens. During studies on the feasibility of replacing FO with relatively environmentally benign natural oil esters, with similar flow properties, such as methyl soyate (MS), it was observed that FO and MS aerosols and vapors were lethal to Salmonella typhimurium strains (Ames strains used to test for mutagenic activity in the Modified Ames Assay) even after very short exposures. It was further shown that vapors produced from the vegetable oil esters under certain conditions exhibited antimicrobial activity against a wide range of Gram-positive and Gram-negative bacteria. In this study, we examined the antimicrobial properties of volatile organic compounds detected in vegetable oil ester vapors. The experiments involved introduction of a known amount of specific compounds present in oil smoke vaors, individually and in combination, into an exposure chamber containing nutrient agar petri dishes inoculated with Salmonella typhimurium. Petri dishes were removed from the chamber after varied exposure periods to determine survival of the bacteria. The results of the experiments showed that individual compounds exhibited antimicrobial activity but lower than the vapors produced during thermal aerosol generation process suggesting the antimicrobial activity of the vapors is likely a synergistic activity of multiple components of the vapors.
文摘The canopy stomatal movement, a plant physiological process, generally occurs within leaves but its influence on exchange of CO2, water vapor, and sensible heat fluxes between atmosphere and terrestrial ecosystem. Many studies have documented that the interaction between leaf photosynthesis and canopy stomatal conductance is obvious. Thus, information on stomatal conductance is valuable in climate and ecosystem models. In current study, a newly developed model was adopted to calculate canopy stomatal conductance of winter wheat in Huang-Huai-Hai (H-H-H) Plain of China (31.5 - 42.7°N, 110.0 - 123.0°E). The remote sensing information from NOAA-AVHRR and meteorological observed data were used to estimate regional scale stomatal conductance distribution. Canopy stomatal conductance distribution pattern of winter wheat on March 18, 1997 was also presented. The developed canopy stomatal conductance model might be used to estimate canopy stomatal conductance in land surface schemes and seems can be acted as a boundary condition in regional climatic model runs.
