共查询到20条相似文献，搜索用时 31 毫秒
1.
A. D. Anderson 《Water, air, and soil pollution》1973,2(4):427-438
A significant number of thepresent long-range subsonic jet aircraft flights are in the stratosphere. Based on fuel consumption, an equivalent of 107 SST aircraft (Concorde) have been flying in the stratosphere each year from 1960 to 1970 (620 equivalent SST in 1990). Subsonic jets in 1990 will burn about 1.6 times as much fuel in the stratosphere as SST aircraft. Based on a Concorde emission index of 12.5 for NO, the amount of NOx emitted by subsonic jets in the stratosphere from 1960 to 1970 is equivalent to an average of 20 Concordes (444 Concordes in 1990). Available information concerning mixing and transport in the atmosphere indicates that both subsonic jets and the SST will fly in the same atmospheric environment in the upper troposphere and lower stratosphere insofar as dissipation of their exhaust pollutants is concerned. The tropopause is not an effective barrier to mixing of stratospheric and tropospheric air. Many processes contribute to mixing in the lower stratosphere where the residence time of contaminants is of the order of months instead of years. 相似文献
2.
W. D. Saunders E. Robinson D. R. Cronn R. A. Ramussen D. Pierotti 《Water, air, and soil pollution》1978,10(4):421-439
This research determined the spatial and temporal distribution of flu orotrichloromethane (F-11) and nitrous oxide (N2O) in the troposphere, across the tropopause and into the lower stratosphere. Four airborne field data collections using a Learjet extend over nearly 2 yr (May 1975 to April 1977). For interpretive purposes, the atmosphere was divided into three analysis layers in the vertical, including the troposphere, a tropopause zone, and the lower stratosphere. F-11 and N2O are vertically well-mixed in the troposphere and concentrations of both compounds decrease in the tropopause zone and to a lesser degree in the lower stratosphere. The importance of the prevailing meteorology in the analysis near the tropopause is shown. The samples collected during the North American flights of October 1976 (latitude range 65°N to 18°N) were categorized into groups indicating their origin in either a high, middle, or low latitude air mass based on a 24 h wind trajectory analysis. The tropospheric samples of F-11 collected in high latitude air masses had higher concentrations than those collected in low latitude air masses. The tropospheric data indicated an increase in F-11 concentration with time. Nitrous oxide concentrations appear to be stable both spatially and temporally. 相似文献
3.
4.
A total of 329 size distributions, obtained from measurements of atmospheric aerosols collected at altitudes from the surface to 9 km, was tested for lognormality using the modified Kolmogoroff-Smirnov test. Samples were collected at Scottsbluff, Nebraska; Death Valley, California; and over the Pacific Ocean about 250 km west of Santa Barbara, California. When considered as volume density distributions, 98% of those tested were lognormal at the 5% level of significance with geometric means in the range of 0.4 to 4 μm. When the particle size range from 0.13 to 5.6 μm was divided into 48 size intervals, in which the number of particles in each interval was normalized to the total number, the number of particles within most class intervals above I μm was lognormally distributed at the 5% level. Below 1 μm lognormality appeared to be less likely at both high and low sampling altitudes. Concentrations of Cl, S, K, Ca, Si, and Ti measured for the same altitudes and at the same locations were in general lognormally distributed. Calculations which compared the coagulation rate of a size distribution of fixed functional form with that of a mean of size distributions formed by the coagulation of aerosols contained in small volumes, each having a particle distribution in which the number of particles in each size class was lognormally distributed about the mean, showed a probably insignificant difference. Based on the above results, the authors speculate that the global aerosol may be described by three overlapping lognormal distributions. 相似文献
5.
Louis Achitoff 《Water, air, and soil pollution》1973,2(3):357-363
Almost five years ago, the Sixteenth Session of the ICAO Assembly adopted a resolution on aircraft noise in the vicinity of airports. The resolution was followed by a special international meeting on noise in Montreal in 1969 which called for recommendations for the development of noise requirements for existing subsonic jet aircraft “as a matter of the utmost urgency.” Despite increasing public, local and congressional demands for noise relief and the demonstrated technical feasibility of modifying current aircraft to afford significant noise reductions, nothing of a tangible nature, other than research, has been accomplished to date. While curfews and restrictive legislation limiting the growth of aviation have abounded, U.S. governmental agencies have failed to carry out the mandate given them by Public Law 90-411 in 1968 which directed the FAA to “... prescribe and amend such rules and regulations ... to provide for the control and abatement of aircraft noise ...”, as far as the existing fleet of aircraft is concerned. 相似文献
6.
Ardeleanu Adriana Loranger Sylvain Kennedy Greg L'Espérance Gilles Zayed Joseph 《Water, air, and soil pollution》1999,115(1-4):411-427
Since 1990, methylcyclopentadienyl manganese tricarbonyl (MMT) has been added to all gasoline in Canada as an antiknock agent. The objective of this study is to determine the percentage of manganese emitted by different types of automobiles and to evaluate the size and chemical characteristics of the Mn-containing particles. Nine vehicles with different mileage and engine capacity were tested using standard procedures for urban and highway driving cycles. One ran on gasoline without MMT and served as a control. The particles were collected using two separate systems: a trapping device consisting of a water tank connected to the tailpipe and a pumping device linked to a cassette containing Teflon filters. Water samples were analyzed by neutron activation to determine the amount of Mn emitted at the tailpipe for each test. Teflon filters were analyzed by electron microscopy to determine the size and the chemical characteristics of the particles. The amount of manganese emitted from the tailpipe varied from 4 to 41% of the manganese consumed, depending on the driving cycle and the vehicle. For the urban cycle, the emission rate was positively correlated with previous mileage. Almost all particles found on teflon filters had a size less than 5 μm. They appeared to be mainly Mn oxides but other elements could be masked by the gold and paladium peaks. 相似文献
7.
冀北山地不同海拔华北落叶松人工林枯落物和土壤水文效应 总被引：11，自引：2，他引：11
对冀北山地4个海拔梯度的华北落叶松(Larix principis-rupprechtii)人工林枯落物层及土壤层水文效应进行研究。结果表明:枯落物总蓄积量、最大持水量、有效拦蓄能力均随海拔升高而增大,枯落物总储量在8.19～39.49t/hm2之间,最大持水量在17.76～74.12t/hm2之间,有效拦蓄能力在14.56～54.60t/hm2之间。枯落物持水量与浸泡时间呈明显对数关系,枯落物吸水速率与浸泡时间呈明显幂函数关系。土壤容重随海拔升高而减小,变化范围为0.89～1.13g/cm3,总孔隙度随海拔升高先增大而后减小,土壤层有效持水量随海拔升高先减小而后增大,土壤入渗速率与入渗时间呈明显幂函数关系。 相似文献
8.
Jae-Cheol Nam Deb J. Fish Alan J. Thorpe Soon-Ung Park 《Water, air, and soil pollution》2001,130(1-4):361-366
A quantitative study of the amount of air transported between the boundary layer and the free atmosphere is important for understanding air quality and upper tropospheric ozone, which is a greenhouse gas. Frontal systems are known to be an effective mechanism for the vertical transport of pollutants. Numerical experiments have been performed with a simple two-dimensional front model to simulate vertical transport of trace gases within developing cold fronts. Three different trace gases experiments have been done numerically according to the different initial fields of trace gases such as aerosol, ozone and H2O2. Trace gas field tilts to the east while the front tilts to the west. Aerosol simulation shows that pollutants can be transported out of the boundary to altitudes of about 10 km. The stratospheric ozone is brought downwards in a tropopause fold behind of the frontal surface. The meridional gradient in trace gas (H2O2) can cause a complicate structure in the trace field by the meridional advection. 相似文献
9.
Air pollutants emissions from traffic are very closely connected to urban air quality, in a local scale, as well as to global
problems like climate change, in a large scale. Road transport air pollutants emissions represent, in most cases, a critical
parameter for a comprehensive and successful understanding of the mechanisms governing the air pollutants concentrations.
Hence, reliable estimations and comprehension of road transport emissions are indispensable in order to set reliable strategies
in the direction of air pollution abatement and management of air pollutants and greenhouse gases emissions. In this framework,
in the present work, the emissions of air pollutants from road transport in Greece will be presented for the whole period
1990–2009 as it was found that a detailed, accurate and reliable emissions inventory was missing. The whole period emissions
variation has clarified the impact of the change in the vehicle fleet, the engine technologies and the fuel quality. The calculated
results have revealed that the age of the vehicles and the corresponding engine technology are the critical parameters determining
the amount of the pollutants emitted. This was mainly observed in both passenger cars and heavy duty vehicles demonstrating
the importance of a renewal programme of the old circulating vehicles in order to set an effective air pollution abatement
strategy. Passenger cars were found to be responsible for the major part of most air pollutants emissions except from nitrogen
oxides and particulates emissions. Heavy duty vehicles contribute more than 66% to nitrogen oxides and particulates emissions.
For the whole time period, all calculated pollutants present a decreasing trend, with the exception of carbon dioxide and
nitrous oxide which increase constantly, ranging from −96% for sulphur dioxide to −1% for PM10. 相似文献
10.
Jamalam Lumbanraja Sutopo Ghani Nugroho Hermanus Suprapto Sunyoto Wayan Sabe Ardjasa Makoto Kimura 《Soil Science and Plant Nutrition》2013,59(2):479-482
In relation to global warming, a great deal of attention has been paid to methane (CH4 ) emission from paddy fields. The amount of CH4 emitted from paddy fields is now estimated to account for about 12% of the total CH4 emission according to Prather et al. (1995). Harvested area of rough rice in Asia covered 1,320,000 km2 in 1990 and 38% of the area was estimated to be maintained under rainfed conditions (IRRI 1991). 相似文献
11.
皖西山区海拔高度对西洋参有效成分的影响 总被引：7，自引：0，他引：7
测定了皖西山区不同海拔高度西洋参成品参的折干率、总皂甙、总糖、还原糖及粗淀粉的含量，并分析了不同海拔高度上主要气象要素对各项值的影响。结果表明：折干率与山区实效积温的垂直变化呈正相关（R＝0．8373），在海拔600－900m之间，实效积温高，折干率较高；总皂甙含量与年日照时数的垂直变化呈正相关（R＝0．7352），在海拔600－850m范围内总皂甙含量较高，而在海拔850－1000m范围内含量较低，在1000m以上的岭头又回升较快：总糖与还原糖的含量均随海拔的升高而增加，且与生长季（4－9月）15cm地温的垂直变化呈负相关（R1＝－0．9870，R2＝－0．9628）；粗淀粉含量变化与生长季实效积温垂直变化呈正相关，在海拔600－850m之间，粗淀粉含量较高。 相似文献
12.
随着全球能源消耗加剧,有限的石化燃料已难以满足人们对能源的需求;而汽车保有量却不断增加,使得车辆向大气中排出的有害污染物急剧增加,这对内燃机行业发展提出了新的要求和挑战。因此,各国从能源安全和环保的角度出发,开始寻找新型燃烧模式,实现内燃机的高效清洁燃烧。酯类含氧燃料作为石化燃料的替代品或添加剂,在燃烧过程中,可提供额外的氧,能使燃料进行充分燃烧,改善燃料物化性质,达到降低有害物质排放、提高燃烧性能的目的,故开发新型酯类含氧燃料有着环保和缓解对石化燃料依赖的双重意义。该研究对生物柴油、长链脂肪酸醚基酯、碳酸酯类、醚酯类、乙酰丙酸酯类清洁含氧燃料的理化性质、排放特性以及在内燃机上的应用进行了讨论,分析酯类含氧燃料的优缺点,并指出酯类含氧燃料应用趋势以及未来研究建议。 相似文献
13.
为探究不同海拔条件下甲醇/柴油反应活性控制压燃（reactivity controlled compression ignition, RCCI）发动机的运行特性,该研究基于甲醇/柴油双燃料发动机试验台架,试验研究1 800r/min、100%负荷和3 200r/min、100%负荷下不同甲醇替代率、柴油喷射正时对发动机燃烧与排放性能的影响规律。结果表明：不同海拔条件下随着甲醇替代率的增加,缸压和瞬时放热率峰值逐渐升高,燃烧始点和燃烧中心前移,当量有效燃油消耗率（equivalent brake specific fuel consumption, ESFC）降低,有效热效率升高,NOx和碳烟排放大幅降低,THC（total hydrocarbons）和CO排放增加。1 800 r/min、100%负荷工况下,甲醇替代率由0增至20%,0、1 000、2 000m海拔下最大缸压平均增加1.72MPa,瞬时放热率峰值平均升高25.08J/(°),ESFC平均降低4.67%,有效热效率平均升高4.90%,NOx和碳烟排放分别平均降低16.63%和50%,THC和CO排放量分别平均增加142.03、388.18 mg/kg。3 200 r/min下甲醇替代率由0增至7%,不同海拔高度下ESFC平均降低1.76%,有效热效率平均升高1.79%,NOx和碳烟排放量分别平均降低8.17%和20.70%。海拔高度由0升至2 000m,1 800r/min、20%甲醇替代率与3 200r/min、7%甲醇替代率下,瞬时放热率峰值分别降低4.80和8.08J/(°),燃烧中心分别推迟1.44°和1.43°,有效热效率分别降低0.82%和0.68%,ESFC分别升高2.10%和1.99%,NOx排放量分别减少10.61%和7.35%,碳烟排放分别增加26.54%和32.12%,THC排放分别升高29.88%和15.45%,CO排放量分别增加22.42%和18.15%。固定甲醇替代率后,随着柴油主喷正时提前,不同海拔条件下缸压和放热率峰值逐渐升高,燃烧中心向上止点靠近,ESFC逐渐降低,有效热效率升高,碳烟排放减少,NOx、THC和CO排放增加。1 800 r/min、15%甲醇替代率下,主喷正时从-1.5°提前至-7.5°,不同海拔高度下ESFC平均降低8.27%,有效热效率平均升高9.08%,碳烟排放平均减少90.94%。为提升高海拔条件下甲醇/柴油RCCI发动机的热效率和燃油经济性,可以适当增大柴油主喷正时。研究结果可为不同海拔环境下甲醇/柴油RCCI发动机燃烧与污染物排放控制优化提供参考。 相似文献
14.
Streets David G. Tsai Nancy Y. Akimoto Hajime Oka Kaoru 《Water, air, and soil pollution》2001,130(1-4):187-192
Acid deposition is a serious problem throughout much of Asia. Emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) have been increasing steadily, as nations strive to increase their levels of economic development. Coal and fuel oil have been the main choices for powering industrial development; and, until recently, only a few countries had taken steps to avert the atmospheric emissions that accompany fuel combustion. This paper discusses trends in emissions of SO2 and NOx that have occurred in Asian countries in the period 1985–1997, using results from the RAINS-Asia computer model and energy-use trends from the IEA Energy Statistics and Balances database. Emissions of SO2 in Asia grew from 26.6 Tg in 1985 to 33.7 Tg in 1990 and 39.2 Tg in 1997. Though SO2 emissions used to grow as fast as fossil-fuel use, recent limitations on the sulfur content of coal and oil have slowed the growth. The annual-average emissions growth between 1990 and 1997 was only 2.2%, considerably less than the economic growth rate. Emissions of NOx, on the other hand, continue to grow rapidly, from 14.1 Tg in 1985 to 18.7 Tg in 1990 and 28.5 Tg in 1997 (6.2% per year between 1990 and 1997), with no signs of abating. Thus, though SO2 remains the major contributor to acidifying emissions in Asia, the role of NOx will become more and more important in the future. 相似文献
15.
Effect of fire on solute release from organic horizons under larch forest in Central Siberian permafrost terrain 总被引：1，自引：0，他引：1
To evaluate the effects of forest fire and post-fire stand recovery on the organic layer chemistry and solute release within mound and trough microrelief elements (termed earth hummock microtopography) that mainly distribute permafrost affected area, we chose five fire plots (larch forests burned in 1951, 1981, 1990, 1994 and 2005) paired with adjacent control plots in mature larch forests in Central Siberian permafrost terrain. We determined total carbon, nitrogen and ash content in solid organic soils, and analyzed total carbon, nitrogen, bases and major anions in water extracts. There was a significant correlation between water-extracted organic carbon (WEOC) and total carbon (kg m−2) in area basis, implying that the quantity of total carbon was a major factor in WEOC production. WEOC correlated negatively with pH, indicating strong control by organic horizons (organic solute leaching) on soil acidity and base cation dynamics. The sum of water extractable base cations was also correlated significantly to total carbon, indicating that cations can be released through organic matter decomposition. Organic horizons in troughs in burned plots released greater amounts of Ca, Mg and K than those in mounds, probably due to greater content of organic matter as a cation source. Anions including nitrate and phosphate and WEOC also accumulated in trough depressions, due probably to organic matter degradation. The contrasting distribution of solutes between mounds and troughs in burned plots seems to be controlled by organic horizon development via changes in microtopography after forest fires. 相似文献
16.
Major factors (emissions and meteorology) controlling pollution patterns in Moscow are discussed in the context of different types of urban land use. Nitrogen oxide pollution is one of the main air quality problems in the city. Power generation is the major source of nitrogen oxides: in 1994, it accounted for 63% of the total NOx emissions with transport contributing 30%. CO emissions are produced almost entirely by road transport. An increase in CO levels has been observed since 1990 in line with growing car ownership. Analyses of seasonal and diurnal variations in CO, NO and NO2 concentrations are presented. Meteorological conditions during an intense pollution episode are analysed in the context of the characteristics of the main sources of pollution. The occurrence of high levels of CO concentrations is associated with high pressure systems, surface-based inversions and low wind speeds. High concentrations of NO2 are caused by fumigation of the surface with pollutants emitted by power plants. The passage of warm weather fronts, the decay of elevated temperature inversions, and stronger winds are identified as meteorological condition leading to NO2 build-up. 相似文献
17.
京津冀秸秆养分资源及秸秆焚烧气体污染物排放定量估算 总被引：7，自引：2，他引：5
为推动区域农作物秸秆综合利用,减少秸秆露天焚烧气体对环境的影响,以京津冀地区为研究对象,评估分析了各类农作物秸秆资源产生、利用状况及其应用潜力,并定量估算了该地区主要农作物秸秆露天焚烧气体污染物排放特征。结果表明,2012年京津冀地区农作物秸秆资源总产量为5 406.9万t,秸秆中氮、磷、钾养分资源总量分别达到3.7×10~4、7.4×10~4、1.0×10~6 t。秸秆资源化利用方式主要以还田为主,北京市、天津市、河北省还田量分别占秸秆量的67.7%、27.3%和61.2%。秸秆露天焚烧主要以小麦和玉米秸秆为主,占田间秸秆焚烧总量的93.03%,焚烧排放的污染物总量分别达到1.0×10~6和4.8×10~5 t。基于京津冀地区秸秆利用现状,建议因地制宜地推动秸秆全量化利用,并在秸秆还田机制、离田利用机制、组织管理机制、技术研发机制等方面出台系统配套的政策措施,以期为中国不同区域秸秆资源的科学利用提供参考。 相似文献
18.
William E. Franklin 《Water, air, and soil pollution》1975,4(2):175-189
The paper industry has traditionally sought fibrous resources from trees, wood residues and waste paper. Emphasis is shifting back to waste paper after 30 yr of relative decline in recycling. Management of fiber resources by major timber holding companies is being expanded to include waste paper. In the next decade the structure of the paper industry will reflect a residuals based process technology relating to both city and forest. Recovery of waste paper can be feasible with source separation or dry separation technology. The outlook for recycling more old newspapers, old corrugated containers and mixed papers from office buildings is very good. Waste paper use in the U.S.A. will double between 1972 and 1985 from 13 million tons to 26 million tons. In addition, a world fiber supply shortage will stimulate further recovery and export of waste fibers. The energy content of paper is about 7500 Btu lb?1, not much below that of Wyoming coal. Recovery of the energy content of paper is an integral part of current efforts to convert mixed wastes to fuel or steam. By 1990 about 50 % of the waste paper generated will be usefully recovered - about 30 % will be recycled, or exported and 20 % will be burned for its energy content. 相似文献
19.
Burke MP Hogue TS Ferreira M Mendez CB Navarro B Lopez S Jay JA 《Water, air, and soil pollution》2010,212(1-4):369-385
Mercury (Hg) stored in vegetation and soils is known to be released to the atmosphere during wildfires, increasing atmospheric stores and altering terrestrial budgets. Increased erosion and transport of sediments is well-documented in burned watersheds, both immediately post-fire and as the watershed recovers; however, understanding post-fire mobilization of soil Hg within burned watersheds remains elusive. The goal of the current study is to better understand the impact of wildfire on soil-bound Hg during the immediate post-fire period as well as during recovery, in order to assess the potential for sediment-driven transport to and within surface waters in burned watersheds. Soils were collected from three southern California watersheds of similar vegetation and soil characteristics that experienced wildfire. Sampling in one of these watersheds was extended for several seasons (1.5 years) in order to investigate temporal changes in soil Hg concentrations. Laboratory analysis included bulk soil total Hg concentrations and total organic carbon of burned and unburned samples. Soils were also fractionated into a subset of grain sizes with analysis of Hg on each fraction. Low Hg concentrations were observed in surface soils immediately post-fire. Accumulation of Hg coincident with moderate vegetative recovery was observed in the burned surface soils 1 year following the fire, and mobilization was also noted during the second winter (rainy) season. Hg concentrations were highest in the fine-grained fraction of unburned soils; however, in the burned soils, the distribution of soil-bound Hg was less influenced by grain size. The accelerated accumulation of Hg observed in the burned soils, along with the elevated risk of erosion, could result in increased delivery of organic- or particulate-bound Hg to surface waters in post-fire systems. 相似文献
20.
基于拉瓦尔效应的超音速喷嘴雾化性能分析与试验 总被引：1，自引：0，他引：1
为提高喷嘴的雾化性能,得到理想的雾滴粒径和均匀的雾云分布,该文首先对超音速雾化喷嘴的雾化原理进行了分析,应用拉瓦尔喷管超音速原理,对雾化喷嘴内部阀芯的锥形结构作了改进,结合Fluent流体动力学软件,分析了拉瓦尔式阀芯结构内部流场速度分布规律,然后通过喷雾试验对比分析了改进前后喷嘴的雾化效果,并探究了不同运行参数对拉瓦尔式结构喷嘴雾化性能的影响规律。数值仿真结果表明,拉瓦尔式阀芯能够产生超音速气流,对增大气液两相速度差具有显著效果;试验结果表明,改进后的拉瓦尔式喷嘴在雾化性能和效果上优于原锥形式喷嘴,气压和气液压力比的增大以及水压的减小均有利于雾滴粒径的减小,其中气液压力比在0～3区间内,雾滴粒径下降幅度高达90.56%,当气液压力比为6时,雾滴粒径达到最小值18.52μm。该文研究内容可为超音速雾化喷嘴进一步研究以及新型喷雾设备的研发提供参考。 相似文献