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David Fowler Rognvald Smith Jennifer Muller John Neil Cape Mark Sutton Jan Willem Erisman Hilde Fagerli 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):41-47
Emissions of sulphur and oxidized nitrogen compounds in Europe have been reduced following a series of control measures during
the last two decades. These changes have taken place during a period in which the primary gases and the wet deposition throughout
Europe were extensively monitored. Since the end of the 1970s, for example land based sulphur emissions declined by between
90 and 70% depending on the region. Over the same period the total deposition of sulphur and its partitioning into wet and
dry deposition have declined, but the spatial pattern in the reduction in deposition differs from that of emission and has
changed with time. Such non-linearities in the emission-deposition relationship are important to understand as they complicate
the process of assessing the effects of emission reduction strategies. Observed non-linearities in terrestrial sulphur emission-deposition
patterns have been identified in north west Europe due to increases in marine emissions, and are currently slowing the recovery
of freshwater ecosystems. Changes in the relative amounts of SO2 and NH3 in air over the last two decades have also changed the affinity of terrestrial surfaces for SO2 and have therefore changed the deposition velocity of SO2 over substantial areas. The consequence of this effect has been the very rapid reduction in ambient SO2 concentration in some of the major source areas of Europe, where NH3 did not change much. Interactions between the different pollutants, generating non-linearities are now being incorporated
in long-range transport models to simulate the effects of historical emission trends and to provide projections into the future.
This paper identifies non-linearities in emission deposition relationships for sulphur and nitrogen compounds in Europe using
data from the EMEP long-rang transport model and measured concentration fields of the major ions in precipitation and of SO2 and NO2 in surface air. 相似文献
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It is well established that wet deposition of sulphate in the UKhas fallen by a much smaller fraction than have emissions of sulphur dioxide. Dry deposition of sulphur has decreased in proportion to the decline in emissions. A number of suggestionshave been made which offer possible explanations for this non-linearity between emissions and wet deposition. In this paper amodel of the processing of sulphur dioxide by aqueous phase cloudchemistry in a cloudy boundary layer is presented. This work doesnot simulate all the details of the mechanisms by which sulphate is incorporated into precipitation. It does, however, explorethe non-linearity of this oxidation process. It is shown that theoxidation of sulphur dioxide, in these conditions, over the UK isdominated by oxidation by ozone. The rate of sulphate productionis then controlled by the availability of the one basic trace gasin the atmosphere ammonia. Using realistic concentrations of thereacting species this is found to simulate well the observed non-linearity. The model predicts that sulphate and sulphur dioxideconcentrations will be uncorrelated in the cloudy boundary layerbut that ammonium and sulphate will be well correlated. Fieldobservations at a cloudy site in Northern England are consistentwith these predictions. 相似文献
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Fowler D. Sutton M. A. Flechard C. Cape J. N. Storeton-West R. Coyle M. Smith R. I. 《Water, Air, & Soil Pollution: Focus》2001,1(5-6):39-48
Two years of continuous measurements of SO2deposition fluxes to moorland vegetation are reported. The mean flux of 2.8 ng SO2 m-2 s-1 is regulated predominantly by surface resistance (r
c) which, even for wet surfaces, was seldom smaller than 100 s m-1. The control of surface resistance is shown to be regulated by the ratio of NH3SO2 concentrations with an excess of NH3 generating the small surface resistances for SO2. A dynamic surface chemistry model is used to simulate the effects of NH3 on SO2 deposition flux and is able to capture responses to short-term changes in ambient concentrations of SO2, NH3 and meteorological conditions. The coupling between surface resistance and NH3/SO2 concentration ratios shows that the deposition velocity for SO2 is regulated by the regional pollution climate. Recent long-term SO2 flux measurements in a transect over Europe demonstrate the close link between NH3/SO2 concentrations and rc (SO2). The deposition velocity for SO2 is predicted to have increased with time since the 1970s and imply a 40% increase in v
d at a site at which the annual mean ambient SO2 concentrations declined from 47 to 3 g m-3 between 1973 and 1998. 相似文献
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基于G1赋权模型的生态城市发展管理评价 总被引:1,自引:0,他引:1
张文辉 《中国人口.资源与环境》2012,22(5):81-86
以生态城市的发展管理评价作为研究对象,界定了发展管理评价的内涵,认为其具有相互作用和对称破缺等非线性特征,适宜于采用G1赋权模型,以崇明生态岛为例做出了应用研究,初步实现了生态城市发展管理的非线性评价。结果显示,崇明生态岛建设的管理能力指数达到67.81,管理机制指数只有52.39,公众参与指数是59.91,综合管理指数是59.65,表明可持续发展管理水平接近于良好可持续性。鉴于"投资力度超强,管理深度不够"的失衡特征,亟待管理改进。为此,给出主要建议如下:明确综合管理定位,大力推进管理机制的创新和完善,强化社会参与机制;明确行动方略,改变投资扩张型的建设体制模式和运作机制;明确政策重点,推进属地管理和流域管理、强化空间集约管理、统筹城乡数字化网络化发展。应用研究显示,G1赋权模型是生态城市发展管理工作实现非线性评价的有效途径之一,可以接近其非线性判断需求,科学揭示管理诸要素的属性特征和相互关系,有助于合理反映当地管理水平并提出有针对性的改进建议。 相似文献
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基于ABAQUS的呼吸防护面具卡扣装配设计 总被引:1,自引:0,他引:1
在对呼吸防护面具结构和装配力学分析的基础上,确定了卡扣装配尺寸、受力、变形的关系表达式。在表达式的基础上,建立了环型卡扣装配分析模型,并用ABAQUS软件分析了卡扣不同过盈量和插入角对卡扣连接和装配力的影响,进而根据最大装配力、最大应变与许用应变的关系,得到了环型卡扣的最佳过盈量、最佳插入角,满足了装配可靠、连接紧凑和密封性好的要求。 相似文献
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