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1.
生物源与人为源有机气体氧化形成的二次有机气溶胶(SOA)对气候变化和人类健康具有重要影响。SOA的产生与其前体物研究已取得了一些进展,但由于有机气体之间存在复合相互作用以及SOA形成机制复杂,目前对不同有机气体混合体系中SOA的形成认知还比较匮乏。因此,深入了解有机气体多源、复杂的相互作用,摸清有机气体的大气氧化机制、SOA的形成及影响等对深入理解真实大气有机气体化学演变具有指导意义。本文旨在了解复合体系有机气体氧化生成SOA的相关研究进展。一方面总结了复合体系有机气体产生SOA质量浓度、产率、成分、挥发性、光学性质等的变化,侧重于实验室复合体系有机气体氧化对SOA形成的多重影响以及SOA组成元素、分子构成的变化特征,并总结了目前实验室基于模型对复合体系SOA生成的模拟研究和拟合情况;另一方面探究了环境因素,如相对湿度(RH)、温度(T)以及无机气体,如氮氧化物(NOx)、二氧化硫(SO2)、氨气(NH3)等对复合体系有机气体形成SOA的影响。 相似文献
2.
Soluble organic nitrogen in Venezuelan rains 总被引：2，自引：0，他引：2
MILEXI PACHECO LORETO DONOSO EUGENIO SANHUEZA 《Tellus. Series B, Chemical and physical meteorology》2004,56(4):393-395
3.
Uncertainties in data on organic aerosols 总被引：4，自引：0，他引：4
BARRY J. HUEBERT ROBERT J. CHARLSON 《Tellus. Series B, Chemical and physical meteorology》2000,52(5):1249-1255
Organic aerosols are gaining increasing attention because of their importance in studies of radiative forcing of climate. However, there is a potential for large and unquantified biases in most of the published data, which has been derived using variations on the evolved gas analysis method (EGA). We argue that the magnitude of these putative uncertainties makes it impossible both to test hypotheses concerning the variation of organic carbon (OC) with altitude and to develop realistic models of radiative climate forcing. 相似文献
4.
A gas chromatographic study has revealed the presence in volcanic gases of a variety of volatile organic compounds. Of particular interest is the detection of such halocarbons as trichlorofluoromethane (F-11), dichlorodifluoromethane (F-12), dichlorofluoromethane (F-21), CCl4 and CHCl3. The concentrations of these compounds attaining 160 ppb in undilute solfataric gases were determined for the first time. The data obtained confirm the existence of a natural source of halocarbons that have a long lifetime in the troposphere and that play an important role in the greenhouse effect and in the catalytic cycle of destruction of stratospheric ozone. 相似文献
5.
The occurrence of CH2Br2, CH2BrCl, CH2I2, CH2ClI, CHBr3, CHBr2Cl, CHBrCl2 and CH2Br-CH2Br in marine air and seawater from various sampling sites in the region of the Atlantic Ocean have been measured and evaluated. A correlation exists between high concentrations of these compounds in air and in water and the occurrence of algae at the coastlines of various islands (The Azores, Bermuda, Tenerife) and in a region of high bioactivity in the Atlantic Ocean near the West African coast.Real-world air-water concentration ratios derived from measurements in the open ocean identify the water mass near the African coast with its high primary production as a source for the above compounds. This region has to be discussed also as a possible secondary source in which CHBr2Cl, CHBrCl2 and CH2ClI can be formed via halogen-exchange. Whether CHBrCl2 and CH2ClI under-go transformation to CHCl3 and CH2Cl2, respectively, is open to further investigations.Direct photolysis and degradation by OH-radicals lead to a gradient in the marine troposphere with reduced concentrations for the organobromides above the tropospheric boundary layer.Partly presented at: 2nd International Symposium on Biosphere-Atmosphere Exchange, Mainz, F.R.Germany, 16–21 March, 1986. Part VII: Chemosphere
15 (1986) 429–436. 相似文献
6.
T. Anttila A. Kiendler-Scharr Th. F. Mentel R. Tillmann 《Journal of Atmospheric Chemistry》2007,57(3):215-237
Organic aerosol formation resulting from the ozonolysis of α-pinene, myrcene and sabinene was investigated in a large aerosol
chamber in the presence of aqueous seed aerosols. The chemical composition of the particles was monitored by an aerosol mass
spectrometer (Aerodyne Research Inc.) as a function of time and the particle size. Smaller particles were found to contain
more organics relative to sulfate than the larger ones. In contrast, the water to sulfate mass ratio was not dependent on
the particle size. These experimental findings indicate the formation of organic layers on the particles. With the aid of
an aerosol dynamic model we demonstrate that the observations are consistent with the formation of multilayered organic films
having thicknesses of approximately 10 nm. The results also suggest that the films were formed through condensation of low-volatile
oxidation products that did not take up water considerably. Even though dissolution of oxidation products into the particle
aqueous phase cannot be conclusively ruled out, the most plausible interpretation of the results is that the monoterpene ozonolysis
lead to the formation of organic coatings on aqueous aerosols. Such films are likely to form in regions with monoterpene emissions. 相似文献
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8.
植物挥发性有机物的分析方法 总被引：6，自引：0，他引：6
为了分析植物排放到大气中的挥发性有机物，在2000年1-6月期间，与美国国家大气研究中心（NCAR）的科学家共同发展和研究了一套自动的气相色谱系统和分析方法。该系统引入一个小型冰箱以除去空气样品进样时的水分，得到了对挥发性有机物样品进行分析时比较好的准确度。在5℃以及稳定的进样速率的条件下，可以得到比较好的除水效果。对NCAR附近的大气进行了采样，并利用此系统做了分析。本简单介绍此自动系统以及样品分析结果。实验结果表明，此套系统具有良好的重复性和稳定性，主要的挥发性有机物的成分如异戊二烯和单萜烯等具有明显的日变化。 相似文献
9.
Incorporating organic soil into a global climate model 总被引：3，自引：1，他引：2
Organic matter significantly alters a soil’s thermal and hydraulic properties but is not typically included in land-surface
schemes used in global climate models. This omission has consequences for ground thermal and moisture regimes, particularly
in the high-latitudes where soil carbon content is generally high. Global soil carbon data is used to build a geographically
distributed, profiled soil carbon density dataset for the Community Land Model (CLM). CLM parameterizations for soil thermal
and hydraulic properties are modified to accommodate both mineral and organic soil matter. Offline simulations including organic
soil are characterized by cooler annual mean soil temperatures (up to ∼2.5°C cooler for regions of high soil carbon content).
Cooling is strong in summer due to modulation of early and mid-summer soil heat flux. Winter temperatures are slightly warmer
as organic soils do not cool as efficiently during fall and winter. High porosity and hydraulic conductivity of organic soil
leads to a wetter soil column but with comparatively low surface layer saturation levels and correspondingly low soil evaporation.
When CLM is coupled to the Community Atmosphere Model, the reduced latent heat flux drives deeper boundary layers, associated
reductions in low cloud fraction, and warmer summer air temperatures in the Arctic. Lastly, the insulative properties of organic
soil reduce interannual soil temperature variability, but only marginally. This result suggests that, although the mean soil
temperature cooling will delay the simulated date at which frozen soil begins to thaw, organic matter may provide only limited
insulation from surface warming. 相似文献
10.
Light extinction by atmospheric particles is strongly dependent on their chemical composition and water content. Since light extinction directly impacts climate, optical measurements of atmospherically relevant aerosols at varying relative humidities (RH) are needed. Recent studies have highlighted the possibility that some atmospheric aerosols are glassy under ambient conditions. Here, the particle optical growth factor, fRHext, was measured for liquid and glassy particles using cavity ring-down aerosol extinction spectroscopy. The particles were composed of ammonium sulfate (AS), 1,2,6-hexanetriol, sucrose, raffinose, and mixed particles containing AS and either sucrose or raffinose. Both sucrose and raffinose can be glassy at room temperature. For the pure organics, the highly viscous sucrose and raffinose particles have similar optical growth curves to the liquid 1,2,6 hexanetriol particles. However, for particles composed of sucrose or raffinose mixed with AS, optical growth depends on the AS weight-percent, which in turn controls the phase state of the AS and ultimately the water uptake. 相似文献
11.
Jeffrey L. Collett Jr. Pierre Herckes Sarah Youngster Taehyoung Lee 《Atmospheric Research》2008,87(3-4):232
Considerable effort has been put into characterizing the ionic composition of fogs and clouds over the past twenty-five years. Recently it has become evident that clouds and fogs often contain large concentrations of organic material as well. Here we report findings from a series of studies examining the organic composition of radiation fogs in central California. Organic compounds in these fogs comprise a major fraction of total solute mass, with total organic carbon sometimes reaching levels of several tens of mg/L. This organic matter is comprised of a wide variety of compounds, ranging from low molecular weight organic acids to high molecular weight compounds with molecular masses approaching several hundred to a thousand g/mole. The most abundant individual compounds are typically formic acid, acetic acid, and formaldehyde. High concentrations are also observed of some dicarboxylic acids (e.g., oxalate) and dicarbonyls (e.g., glyoxal and methylglyoxal) and of levoglucosan, an anhydrosugar characteristically emitted by biomass combustion. Many other compounds have been identified in fog water by GC/MS, including long chain n-alkanoic acids, n-alkanes, PAH, and others, although these compounds typically comprise a total of only a few percent of fog TOC. Measurements of fog scavenging of organic and elemental carbon reveal preferential scavenging of organic carbon. Tracking of individual organic compounds utilized as source type markers suggests the fogs differentially scavenge carbonaceous particles from different source types, with more active processing of wood smoke than vehicle exhaust. Observations of high deposition velocities of fog-borne organic carbon, in excess of 1 cm/s, indicate that fogs in the region represent an important mechanism for cleansing the atmosphere of pollution. 相似文献
12.
土壤有机质是土壤的重要组成部分,对许多土壤属性有重要影响.利用光谱技术进行土壤有机质的快速测定是实现精细农业的基础.近几十年中,高光谱技术的发展为土壤研究提供了新的手段.受土壤有机质质量分数、组成以及土壤水分、土壤质地的影响,室内光谱的估算结果总体较好;受大气、地表植被等影响,航空或卫星的成像光谱估算精度较低.星载成像技术的进步将在一定程度上提高土壤有机质的估算精度,为快速、大范围土壤有机质质量分数的遥感制图提供技术支持. 相似文献
13.
Xinhui Bi Bernd R.T. Simoneit Guoying Sheng Shexia Ma Jiamo Fu 《Atmospheric Research》2008,88(3-4):256-265
Total suspended particles (TSP), collected during June 2002 to July 2003 in Guangzhou, a typical economically developed city in South China, were analyzed for the organic compound compositions using gas chromatography–mass spectrometry (GC/MS). Over 140 organic compounds were detected in the aerosols and grouped into different classes including n-alkanes, hopanoids, polycyclic aromatic hydrocarbons, alkanols, fatty acids, dicarboxylic acids excluding oxalic acid, polyols/polyacids, lignin products, phytosterols, phthalates and water-soluble sugars. The total amounts of the identified organic compounds including unresolved complex mixture (UCM) ranged from 3112 ng/m3 in spring to 5116 ng/m3 in winter, comprising on seasonal average 2.8% of TSP. Primary organic compounds peaked in winter although there are no heating systems burning fuels in Guangzhou. The highest saccharide levels occurred in fall due to agricultural activities. This study demonstrated that utilization of fossil fuels, biomass burning, soil resuspension and plastic/refuse burning are the major contributors to the identified organic compounds in the urban atmosphere of South China. 相似文献
14.
Deanne D. Grant Jose D. Fuentes Stephen Chan William R. Stockwell Daniel Wang Seydi A. Ndiaye 《Journal of Atmospheric Chemistry》2008,60(1):19-35
The objectives of this study were to identify species and levels of volatile organic compounds (VOCs), and determine their
oxidation capacity in the rural atmosphere of western Senegal. A field study was conducted to obtain air samples during September
14 and September 15, 2006 for analyses of VOCs. Methanol, acetone, and acetaldehyde were the most abundant detected chemical
species and their maximum mixing ratios reached 6 parts per billion on a volume basis (ppbv). Local emission sources such
as firewood and charcoal burning strongly influenced VOC concentrations. The VOC concentrations exhibited little temporal
variations due to the low reactivity with hydroxyl radicals, with reactivity values ranging from 0.001 to 2.6 s−1. The conditions in this rural site were rather clean. Low ambient NO
x
levels limited ozone production. Nitrogen oxide (NO
x
) levels reached values less than 2 ppbv and maximum VOC/NO
x
ratios reached 60 ppbvC/ppbv, with an overall average of 2.4 ± 4.5 ppbvC/ppbv. This indicates that the rural western Senegal
region is NO
x
limited in terms of oxidant formation potential. Therefore, during the study period photochemical ozone production became
limited due to low ambient NO
x
levels. The estimated ozone formation reactivity for VOCs was low and ranged between −5.5 mol of ozone/mol of benzaldehyde
to 0.6 mol/mol of anthropogenic dienes. 相似文献
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A statistically relevant correlation between the reaction rate coefficient, k
OH, for the OH radical reaction with 161 organic compounds in the gas phase at 300 K, and the corresponding vertical ionisation energies E
i,v, reveals two classes of compounds: aromatics where –log(k
OH/cm3s-1)3/2E
i,v(eV)–2 and aliphatics where –log(k
OH/cm3s-1)4/5E
i,v(eV)+3. The prediction of the rate coefficient, k
OH, for the reaction of OH with organic molecules from the above equations has a probability of about 90%. Assuming a global diurnal mean of the OH radical concentration of 5×105 cm3, the upper limit of the tropospheric half-life of organic compounds and their persistence can be estimated. 相似文献
20.
Robert J. Kieber Joan D. Willey Robert F. Whitehead Seth N. Reid 《Journal of Atmospheric Chemistry》2007,58(3):219-235
Significant photodegradation of chromophoric dissolved organic matter (CDOM) in rainwater was observed after exposure to simulated
sunlight. Fluorescence excitation emission spectra (EEMS) of precipitation revealed the presence of four major peaks all of
which degraded upon photolysis with the greatest loss in the region characteristic of marine CDOM. Photobleaching of absorbance
also occurred in the wavelength region between 250 and 375 nm with the greatest loss of absorbance in the upper end of the
UV-A region near 275 nm. There was a strong positive correlation between absorbance loss and total integrated fluorescence
loss suggesting these optical properties and the degree to which they are photobleached in rainwater are directly related.
The quantum yield of CDOM photodegradation in rainwater decreased dramatically with increasing wavelength and decreasing energy
of incoming radiation with the average quantum yield at 325 nm approximately an order of magnitude greater than at 460 nm.
The similarity of photolytic response between rainwater and Cape Fear estuarine CDOM indicates that some fraction of the compounds
that make up rainwater CDOM may be derived from surface sources and/or that the processes that produce or modify humic-like
substances in the atmosphere result in similar types of compounds as non-atmospheric processes. 相似文献