Venus lower atmospheric composition: analysis by gas chromatography

The first gas chromatographic analysis of the lower atmosphere of Venus is reported. Three atmospheric samples were analyzed. The third of these samples showed carbon dioxide (96.4 percent), molecular nitrogen (3.41 percent), water vapor (0.135 percent), molecular oxygen [69.3 parts per million (ppm)], argon (18.6 ppm), neon (4.31 ppm), and sulfuir dioxide (186 ppm). The amounts of water vapor and sulfur dioxide detected are roughly compatible with the requirements of greenhouse models of the high surface temperature of Venus. The large positive gradient of sulfur dioxide, molecular oxygen, and water vapor from the clould tops to their bottoms, as implied by Earth-based observations and these resuilts, gives added support for the presence of major quantities of aqueous sulfuric acid in the clouds. A comparison of the inventory of inert gases found in the atmospheres of Venus, Earth, and Mars suggests that these components are due to outgassing from the planetary interiors.     

Composition and structure of the martian upper atmosphere: analysis of results from viking

Densities for carbon dioxide measured by the upper atmospheric mass spectrometers on Viking 1 and Viking 2 are analyzed to yield height profiles for the temperature of the martian atmosphere between 120 and 200 kilometers. Densities for nitrogen and argon are used to derive vertical profiles for the eddy diffusion coefficient over the same height range. The upper atmosphere of Mars is surprisingly cold with average temperatures for both Viking 1 and Viking 2 of less than 200 degrees K, and there is significant vertical structure. Model calculations are presented and shown to be in good agreement with measured concentrations of carbon monoxide, oxygen, and nitric oxide.     

Apollo lunar module engine exhaust products

Organic combustion products generated by the lunar module descent engine, which burns a 1:1 mixture of unsymmetrical dimethylhydrazine fuel and nitrogen tetroxide oxidizer, have been analyzed. The major gaseous combustion products found were ammonia, water, carbon monoxide, nitrous oxide, oxygen, carbon dioxide, and nitric oxide. The minor products were acetylene, hydrogen cyanide, ethylene, formaldehyde, propadiene, ketene, cyanous acid, hydrazoic acid, various methylamines, acetaldehyde, methyl nitrite, formic acid, nitrous acid, butadiyne, nitrilohydrazines, nitromethane, and nitrosohydrazines with other oxidized derivatives of unsymmetrical dimethylhydrazine and hydrazine. The ion intensities of the various species in all mass spectra were estimated as the following concentrations: the gases (NH(3), H(2)O, CO, NO, O(2), CO(2), and NO(2)), 87.7 percent; compounds of C, H, and O, 6.0 percent; and compounds of C, H, and N (with traces of O), 5.8 percent.     

Air pollution: remote detection of several pollutant gases with a laser heterodyne radiometer

An infrared heterodyne radiometer with a spectral resolution of 0.04 reciprocal centimeters has been used to remotely detect samples of ozone, sulfur dioxide, ammonia, and ethylene at room temperature, and samples of nitric oxide at 390K. Each gas was observed in a background of nitrogen or oxygen at atmospheric pressure. Sensitivities to some of these gases are adequate for detection of ambient concentrations as low as a few parts per billion.     

不同堆肥处理猪粪温室气体排放与影响因子初步研究

利用封闭式测定箱对两种不同堆肥处理方式的猪粪产生的气体进行了取样，然后通过气相色谱分析仪对其所含二氧化碳（CO2）、氧化亚氮（N2O）、甲烷（CH4）进行了测定分析。参考其处理系统获得的温度、湿度、氧气浓度数据，结果表明，在相同条件下，二氧化碳的排放与猪粪内部的氧气状况密切相关，通风良好则排放量就大；而甲烷恰相反，缺氧与较高的湿度会促使甲烷排放；氧化亚氮是其硝化与反硝化过程的产物，若干湿交替，则会增加氧化亚氮的排放量，但其影响因子更为复杂。     

Nitrous oxide emissions from an irrigated cornfield

During the 1978 growing season, nitrous oxide (N(2)O) emissions from a typical well-managed northern Colorado field of corn (Zea mays L.) totaled approximately 2.6 kilograms of nitrogen per hectare, or about 1.3 percent of the applied fertilizer nitrogen. Thirty percent of the loss occurred during the 3 weeks following fertilization while ammonia was being rapidly nitrified, and 59 percent was emitted during the week after the field's first irrigation, when restricted oxygen diffusion favored denitrification. Considering the large spatial and temporal variability of N(2)O emissions from soil, micrometeorological estimates of vertical N(2)O flux density compared favorably with estimates based on a simple soil cover method.     

Mechanisms of nitrogen dioxide reactions: initiation of lipid peroxidation and the production of nitrous Acid

The reactions of nitrogen dioxide with cyclohexene have been studied as a model for the reactions that occur between nitrogen dioxide in smoggy air and unsaturated fatty acids in pulmonary lipids. As predicted from earlier studies at high nitrogen dioxide concentrations, this gas reacts with cyclohexene predominantly by addition to the double bond at nitrogen dioxide concentrations of 1 percent (10,000 parts per million) to 40 percent in nitrogen; in the presence of air or oxygen, this reaction initiates the autoxidation of the alkene. However, at concentrations below 100 parts per million in nitrogen, nitrogen dioxide reacts with cyclohexene almost exclusively by abstraction of allylic hydrogen; this unexpected reaction also initiates the autoxidation of the alkene in the presence of oxygen or air, but it leads to the production of nitrous acid rather than of a product containing a nitro group attached to a carbon atom. The nitrous acid can react with amines to produce nitrosamines. Moreover, the nitrite ion produced by the hydrogen abstraction mechanism would be expected to diffuse throughout the body, unlike nitrated lipids that would be confined to the pulmonary cavity. These findings have been confirmed with methyl oleate, linoleate, and linolenate; some of the kinetic features of the nitrogen dioxide-initiated autoxidation of these unsaturated fatty acids have been studied.     

Enzyme reaction rates at limited water activities

A well-mixed powder consisting of dry urea and urease exposed to air containing discrete amounts of water vapor showed a release of carbon-14 dioxide above 60-percent relative humidity. The relative activity of urease followed the water-vapor adsorption isotherm of urease. The minimum amount of water required for the reaction observed was 1.3 moles per mole of side-chain polar groups of the urease protein.     

Fixation of nitrogen in the prebiotic atmosphere

Reactions between nitrogen and water in the air surrounding lightning discharges can provide an important source of nitric oxide even under conditions where oxygen is a minor atmospheric constituent. Estimates are given for the associated source of soluble nitrite and nitrate. It is shown that lightning and subsequent atmospheric chemistry can provide a source of nitrate for the primitive ocean as large as 106 tons of nitrogen per year, sufficient to fill the ocean to its present level of nitrate in less than 10(6) years.     

Biomass burning in the tropics: impact on atmospheric chemistry and biogeochemical cycles

Biomass burning is widespread, especially in the tropics. It serves to clear land for shifting cultivation, to convert forests to agricultural and pastoral lands, and to remove dry vegetation in order to promote agricultural productivity and the growth of higher yield grasses. Furthermore, much agricultural waste and fuel wood is being combusted, particularly in developing countries. Biomass containing 2 to 5 petagrams of carbon is burned annually (1 petagram = 10(15) grams), producing large amounts of trace gases and aerosol particles that play important roles in atmospheric chemistry and climate. Emissions of carbon monoxide and methane by biomass burning affect the oxidation efficiency of the atmosphere by reacting with hydroxyl radicals, and emissions of nitric oxide and hydrocarbons lead to high ozone concentrations in the tropics during the dry season. Large quantities of smoke particles are produced as well, and these can serve as cloud condensation nuclei. These particles may thus substantially influence cloud microphysical and optical properties, an effect that could have repercussions for the radiation budget and the hydrological cycle in the tropics. Widespread burning may also disturb biogeochemical cycles, especially that of nitrogen. About 50 percent of the nitrogen in the biomass fuel can be released as molecular nitrogen. This pyrdenitrification process causes a sizable loss of fixed nitrogen in tropical ecosystems, in the range of 10 to 20 teragrams per year (1 teragram = 10(12) grams).     

Structure of the neutral upper atmosphere of Mars: results from viking 1 and viking 2

Neutral mass spectrometers carried on the aeroshells of Viking 1 and Viking 2 indicate that carbon dioxide is the major constituent of the martian atmosphere over the height range 120 to 200 kilometers. The atmosphere contains detectable concentrations of nitrogen, argon, carbon monoxide, molecular oxygen, atomic oxygen, and nitric oxide. The upper atmosphere exhibits a complex and variable thermal structure and is well mixed to heights in excess of 120 kilometers.     

A mercury-catalyzed, high-yield system for the oxidation of methane to methanol

A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate ( approximately 43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10(-7) mole per cubic centimeter per second and Hg(II) turnover frequency of 10(-3) per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH(3)HgOSO(3)H, 1. Under the reaction conditions, 1 readily decomposes to CH(3)OSO(3)H and the reduced mercurous species, Hg(2)(2+) The catalytic cycle is completed by the reoxidation of Hg(2)(2+) with H(2)SO(4) to regenerate Hg(II) and byproducts SO(2) and H(2)O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.     

Role of deep cloud convection in the ozone budget of the troposphere

Convective updrafts in thunderstorms prolong the lifetime of ozone (O(3)) and its anthropogenic precursor NOx [nitric oxide (NO) + nitrogen dioxide (NO(2))] by carrying these gases rapidly upward from the boundary layer into a regime where the O(3) production efficiency is higher, chemical destruction is slower, and surface deposition is absent. On the other hand, the upper troposphere is relatively rich in O(3) and NOx from natural sources such as downward transport from the stratosphere and lightning; convective overturning conveys the O(3) and NOx toward the Earth's surface where these components are more efficiently removed from the atmosphere. Simulations with a three-dimensional global model suggest that the net result of these counteractive processes is a 20 percent overall reduction in total tropospheric O(3). However, the net atmospheric oxidation efficiency is enhanced by 10 to 20 percent.     

Synthesis of Isocyanic Acid from Nitric Oxide over Palladium and Iridium Catalysts

A novel and convenient synthesis of isocyanic acid (HNCO) and its trimer isocyanuric acid has been obtained by the conversion of nitric oxide (NO). Nitric oxide, carbon monoxide, and hydrogen mixed in helium at the level of 0.3 to 5 percent reacted over iridium and palladium catalysts at 280 degrees to 450 degrees C to form HNCO in 60 to 75 percent yield. Major side products were ammonium cyanate at low temperature and ammonia or nitrogen at high temperature. Total conversion of nitrogen from NO to NCO reached 73 percent over palladium and 86 percent over iridium.     

Stratospheric nitrogen dioxide in the vicinity of soufriere, st. Vincent

In April 1979, measurements of nitrogen dioxide in the upper atmosphere were made near Soufriere Volcano by twilight optical-absorption techniques. The derived value of 5 x 10(15) molecules per square centimeter column implies an enhancement of 25 percent over earlier abundances measured in the same latitudinal regions. This enhancement may represent the normal stratospheric variability of nitrogen dioxide in the equatorial region but in any case may be considered an upper limit to the volcano's effect on the total nitrogen dioxide abundance.     

Relative humidity: important modifier of pollutant uptake by plants

Laboratory measurements of foliar uptake of sulfur dioxide and ozone by red kidney beans demonstrated a strong effect of relative humidity on internal pollutant dose. Foliar uptake was enhanced two- to threefold for sulfur dioxide and three- to fourfold for ozone by an increase in relative humidity from 35 to 75 percent. For the same exposure concentration, vegetation growing in humid areas (such as the eastern United States) may experience a significantly greater internal flux of pollutants than that in more arid regions.     

Interaction between CO<Subscript>2</Subscript> elevation and nitrogen metabolism in two varieties of Guar (<Emphasis Type="Italic">Cyamopsis tetragonoloba</Emphasis>) plants

The aim of the experimental study is to analyse the consequence of carbon dioxide elevation on activity of nitrate reductase (NR; EC 1.6.6.1), nitrite reductase (NiR; EC 1.7.7.1), glutamate synthetase (GOGAT; EC 1.4.1.13) in leguminous Cyamopsis tetragonoloba leaves. Plants were exposed to different atmospheric carbon dioxide concentrations 300 ppm (ambient) and 490 ppm (an elevated) conditions. A decrease in activity of Nitrate Reductase (NR), Nitrite Reductase (NiR), Glutamate Synthetase (GOGAT) was found in elevated condition when compared to ambient condition. Plant nitrogen on dry weight basis was found to decrease under elevation with no significant change in soil nitrogen. Soil pH was found to change significantly under elevation, thus showing a decline in pH and promoting soil acidiosis. Total plant fresh weight (FW) and total plant dry weight (DW), Leaf area/cm² were found increased in elevated condition. Thus, in Cyamopsis tetragonoloba plant it can be concluded that under carbon dioxide elevation Nitrate reductase, Nitrite reductase and Glutamate synthetase activity is suppressed due to a reduced amount of nitrate translocation and NADH availability for reduction in plant which is correlated with reduction in plant total nitrogen content where as plant growth and biomass is enhanced due to higher carbon fixation.     

外源NO对缺氮胁迫下棉花幼苗形态及生长的调控效应

【目的】探讨外源一氧化氮（nitric oxide,NO）对缺氮胁迫下棉花幼苗不同部位叶片以及不同直径范围根系等形态特征及生长情况的影响,分析不同浓度NO对棉花形态生长的调控效应,为外源NO调控棉花生长发育提供理论依据。【方法】在光照培养室内采用水培方法,以农大棉8 号为供试品种,设7 个不同处理,其中以Hoagland全营养液培养的棉花幼苗为对照（CK）,以缺氮Hoagland营养液培养的棉花幼苗为外源NO处理对象,利用外源NO供体硝普钠（sodium nitroprusside,SNP）处理棉花幼苗,设置6 个浓度梯度0 μmol·L^-1（T0）、50 μmol·L^-1（T1）、100 μmol·L^-1（T2）、200 μmol·L^-1（T3）、500 μmol·L^-1（T4）和1 000 μmol·L^-1（T5）,研究不同NO水平对缺氮胁迫下棉花幼苗叶面积、根系形态、耗水量及干物重的影响。【结果】缺氮胁迫抑制棉花幼苗地上部以及地下部的生长,抑制棉花幼苗叶片数和叶面积的增加,降低了幼苗细根（0.05-0.20 mm）、中等根（0.2-0.45 mm）的根长、根表面积、根体积,减少了耗水量以及干物重。不同浓度外源NO对缺氮胁迫下棉花幼苗地上及地下部生长情况的影响不同。低浓度外源NO（SNP浓度为50-100 μmol·L^-1）能缓解缺氮胁迫对棉花幼苗的伤害,显著促进棉花幼苗上部和下部叶片的生长,促进细根和中等根生长,增加细根和中等根的根长、根表面积及根体积,增加棉花幼苗耗水量,显著增加幼苗干物重。当SNP浓度大于100 μmol·L^-1后,随浓度增加,其缓解作用下降。幼苗叶片数、上部和下部叶片的叶面积、细根和中等根的根长、根表面积、根体积、耗水量以及干物重均下降。综合分析认为氮素缺乏环境下,不同浓度外源NO通过影响棉花幼苗地上部以及根系的生长来缓解缺氮胁迫,以100 μmol·L^-1 SNP处理的棉花幼苗生长最好,而高浓度的SNP则加剧缺氮胁迫对棉苗的抑制。【结论】缺氮胁迫下棉花幼苗长势减弱,适宜浓度外源NO（SNP浓度为50-100 μmol·L^-1）能够在一定程度上缓解缺氮胁迫对棉花幼苗造成的伤害,促进棉花幼苗地上和地下部的生长,提高棉花幼苗对缺氮胁迫的耐性。其中以100 μmol·L^-1 SNP缓解效果最显著。     

二氧化氮气相污染物被动采样法的研究

运用基于气体分子扩散理论自制的被动采样器,结合Saltzman法,通过该采样器在室内外进行曝露采样检测NO2的含量.该采样器在空气中曝露24个小时后,测定空气中的NO2浓度可达n×10-3mg/m3,与TH-110C型便携式直流大气采样器测定结果比较,误差在30%以内.     

重庆市“十五”期间酸雨污染特征及成因分析

以5个点降水监测数据为基础,对重庆市“十五”期间酸雨污染的变化趋势、空间分布特征和降水中化学组份构成进行了分析,并从致酸源、大气环境质量、地形特征和气象因素等方面探讨了酸雨形成的主要原因,认为重庆市酸雨污染具有典型的局地性,化石燃料燃烧向大气中排放大量的二氧化硫和氮氧化物是酸雨形成的根本原因,恶劣的大气污染物扩散条件加重了酸雨污染的程度.