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1.
The advection-diffusion equation is used for describing the dispersion of pollutants in a limited area. Methods for preventing dangerous levels of pollutants in ecologically important zones are suggested. The methods are based on the control of emission rates of sources and use the direct and adjoint estimates of the average pollution concentration in the zones. While the direct estimates use solutions of the pollution transport problem and permit to study the ecological situation in the whole domain, the adjoint estimates allow getting information only in the selected zones of the domain. The adjoint estimates are obtained with solutions to the adjoint problem and depend explicitly on the positions of the sources and their emission rates, and on the initial distribution of pollutants in the region. In each such estimate, the adjoint problem solution serves as the influence function that shows the quantitative contribution of every source into the pollution of the corresponding zone. This makes the adjoint estimates very efficient tools in the study of the model response to changes in emission rates and initial conditions, as well as in the development of control strategies. Both non-optimal (sufficient) and optimal control strategies are suggested. Each strategy consists in reducing the emission rates of sources, and defines maximum allowable intensity (in case of optimal control), or sufficient intensity (in case of sufficient control) of each source to avoid violations of hygiene standards. Such criteria are designed taking into account dynamic conditions in the atmosphere or ocean (sea), that is, the processes of propagation, dispersion and transformation of pollutants, as well as the number of sources to control, their locations and the sanitary norms. The control methods developed are illustrated with simple examples using two-dimensional dispersion models. However, these methods can also be applied to three-dimensional models. As an example, in the last part of the article, a three-dimensional model of dispersion is considered. In addition, to expand the scope of application of the methods of control of the intensity of sources, the optimal control strategies are applied to a source that emits a chemical substance to clean aquatic systems contaminated with biofilms (remediation) or oil (bioremediation).  相似文献   

2.
The control of toxic emissions has become of great scientific interest due to the continuous increase of pollutants released into the atmosphere. The fact that the fine particles suspended in the atmosphere have been proved to have a negative impact on human health has also contributed to an increasing interest. This paper focuses on two important items: (1) the experimentally obtained pollution maps of Timisoara, showing the spatial distribution of the concentration of particulate matter (between 0.3–2.5 μm and 2.5–5 μm) over the city area; and (2) the simulation of the dispersion of pollutants emitted by Pro Air Clean Ecologic incinerator in Timisoara, based on specific meteorological conditions. The transport process of the pollutants was investigated numerically with the Close View software. This uses at input the concentration and the properties of the pollutants detected experimentally at the combustion chimney, the effective height of the chimney and the specific meteorological conditions, i.e., air pressure and humidity, velocity and direction of the wind.  相似文献   

3.
Air pollution is a grand challenge of our time due to its multitude of adverse impacts on environment and society,with the scale of impacts more severe in developing countries,including China.Thus,China has initiated and implemented strict air pollution control measures over last several years to reduce impacts of air pollution.Monitoring data from Jan 2015 to Dec 2019 on six criteria air pollutants(SO2,NO2,CO,O3,PM2.5,and PM1o)at eight sites in southwestern China were investigated to understand the situation and analyze the impacts of transboundary air pollutants in this region.In terms of seasonal variation,the maximum concentrations of air pollutants at these sites were observed in winter or spring season depending on individual site.For diurnal variation,surface ozone peaked in the afternoon while the other pollutants had a bimodal pattern with peaks in the morning and late afternoon.There was limited trans-port of domestic emissions of air pollutants in China to these sites.Local emissions enhanced the concen-trations of air pollutants during some pollution events.Mostly,the transboundary transport of air pollution from South Asia and Southeast Asia was associated with high concentrations of most air pollu-tants observed in southwestern China.Since air pollutants can be transported to southwestern China over long distances from the source regions,it is necessary to conduct more research to properly attribute and quantify transboundary transport of air pollutants,which will provide more solid scientific guidance for air pollution management in southwestern China.  相似文献   

4.
Air pollution is the presence of pollutants in the atmosphere from anthropogenic or natural substances in quantities likely to harm human, plant or animal life; to damage human-made materials and structures; to bring about changes in weather or climate; or to interfere with enjoyment of life or property. With regard to the quality of air in most of the megacities of the world, vehicular air pollution plays an important role in deteriorating air quality. Air pollution in Tehran (Capital of the Islamic Republic of Iran) occurs in highly urbanized areas due to mobile anthropogenic sources which in-turn is hastened by unfavorable tohion sector is responsible for much of urban air pollution and can result in high ambient concentrations that harm people, structures, and environment. This paper examines and estimates the tonnage, concentrations and impacts of air pollutants along with control measures aimed at reducing the effect of pollutants released by transportation navigation, in Tehran.  相似文献   

5.
The health risks presented by noxious vehicle emissions inside tunnels has been amplified due to the increasing use of roadway tunnels. Particularly, for adjacent roadway tunnels, vehicular emissions from the upstream tunnel can further deteriorate the air quality within the following tunnels. A scale vehicle tunnel model was designed to experimentally modelled the airflow and pollutants dispersion in contiguous roadway tunnels. The channelling effect on pollutants dispersion between adjacent roadway tunnels was studied, and factors such as ventilation speed, open road section length, traffic condition (e.g. car free, car running and traffic congestion) were considered. Pollutants mass flow rate ratio between downstream and upstream tunnels was calculated to evaluate the variation of the entrained pollutants amount. For the car free condition, pollutant can be easily entrained into the downwind tunnel when the gap distance between roadway tunnels decreased. For the car running condition with fixed tunnel gap distance, the traffic speed variation barely changed the pollutants mass flow rate ratio. Furthermore, evident influences on pollutants concentration were observed from continuous congestion and partial congestion. Lastly, numerical simulation using computational fluid dynamics approach was conducted for the car free scenario, and reasonably good agreements were found for pollutants concentration ratio compared with the experimental data. The results yielded from this study further quantified the relationships among different influential factors on the pollutants dispersion between roadway tunnels, and can contribute to an improved tunnel ventilation system design, especially for the downstream tunnel.  相似文献   

6.
深冰层取心钻探是极地科学考察的重要组成部分。在极地勘探取样过程中做到在获得高质量冰岩心样品的同时,将钻井液对极地环境的污染降低到最低程度,对保护极地原生环境具有重要意义。依据南极科学钻探的地层条件,应用Visual Modflow建立了污染物在雪层中的运移模型,在污染物浓度保持恒定时,对钻孔内污染物进行了数值模拟,预测了10年后污染物在雪中污染羽扩散范围。在此基础上,对比分析了不同弥散系数时,雪对污染物弥散的能力。极地科学钻探使用的钻井液粘度通常是水的10倍,随着污染物粘度的增大,其扩散的距离也将相应减少。研究结果为深入开展极地冰层取心钻探钻井液对极地环境影响评价研究奠定了重要的理论与技术基础。  相似文献   

7.
The removal of volatile organic compounds from biological treatment processes occurs through several mechanisms. These include biodegradation, adsorption onto solids, and air stripping or volatilization to the atmosphere. Volatilization results in fugitive emissions to the atmosphere, which is largely uncontrolled. Recent regulations have called for increased evaluation and control of inadvertent volatile organic compounds emissions from treatment processes. The use oxygen as a parallel volatile compound is extremely useful for prediction of volatile organic compounds removal by air stripping. In this study, the simultaneous biodegradation and air stripping of volatile organic compounds, based on steady state mass balance are examined and a general approach to estimating the dominant removal mechanism is developed. A Monte Carlo simulation technique was used to estimate air stripping over a wide range of operating conditions. Several volatile organic compounds were selected for this study. The results showed the values drived from the model correspond with the experimental data for benzene, toluene, methylene chloride, trichloroethylene, and methyl isobutyl ketone.  相似文献   

8.
弥散理论是污染质在含水层中运移模型的基本理论.但在实际应用中存在着不少问题和争议.本文对污染质在含水层中运移的弥散作用进行了分析探讨.并应用MOC水质模型对弥散参数的作用进行了分析,证明了在一般情况下,污染质在含水层中的运移主要受对流作用控制,弥散参数的变化对水质模型结果的影响相对较小.在特定的水文地质条件下,弥散作用对污染质的运移是重要的.  相似文献   

9.
空气滤膜吸附采集甘肃某农场大气粉尘样品,采用盐酸—硝酸—氢氟酸—高氯酸溶解,电感耦合等离子体质谱法（ICP-MS）同时测定溶液中铬、铜、砷、镉、铅等重金属元素含量,分析农田环境大气颗粒中的重金属元素对农作物的影响,同时验证不同仪器工作参数对测定结果的影响。实验表明：在选定的实验条件下,分析元素的检出限低,准确性和精密度...  相似文献   

10.
ISC-AERMOD dispersion model was used to predict air dispersion plumes from an diesel power plant complex. Emissions of NO2and SO2from stacks (5 numbers) and a waste oil incinerator were studied to evaluate the pollutant dispersion patterns and the risk of nearby population. Emission source strengths from the individual point sources were also evaluated to determine the sources of significant attribution. Results demonstrated the dispersions of pollutants were influenced by the dominant easterly wind direction with the cumulative maximum ground level concentrations of 589.86 μg/m3 (1 h TWA NO2) and 479.26 μg/m3 (1 h TWA SO2). Model performance evaluation by comparing the predicted concentrations with observed values at ten locations for the individual air pollutants using rigorous statistical procedures were found to be in good agreement. Among all the emission sources within the facility complex, SESB-Power (diesel power plant) had been singled out as a significant source of emission that contributed >85% of the total pollutants emitted.  相似文献   

11.
分析了城市环保信息系统建设的现状,基于SuperMap对城市环保信息系统进行系统设计,分析系统的体系结构,设计环保系统的主要功能,在Supermap平台上实现了大气污染扩散、水污染扩散分析等高级功能,为环境保护工程提供了技术支持。  相似文献   

12.
Air pollution has been a major transboundary problem and a matter of global concern for decades. Climate change and air pollution are closely coupled. Just as air pollution can have adverse effects on human health and ecosystems, it can also impact the earth’s climate. As we enter an era of rapid climate change, the implications for air quality need to be better understood, both for the purpose of air quality management and as one of the societal consequences of climate change. In this study, an attempt has been made to estimate the current air quality to forecast the air quality index of an urban station Kolkata (22.65°N, 88.45°E), India for the next 5 years with neural network models. The annual and seasonal variability in the air quality indicates that the winter season is mostly affected by the pollutants. Air quality index (AQI) is estimated as a geometric mean of the pollutants considered. Different neural network models are attempted to select the best model to forecast the AQI of Kolkata. The meteorological parameters and AQI of the previous day are utilized to train the models to forecast the AQI of the next day during the period from 2003 to 2012. The selection of the best model is made after validation with observation from 2013 to 2015. The radial basis functional (RBF) model is found to be the best network model for the purpose. The RBF model with various architectures is tried to obtain precise forecast with minimum error. RBF of 5:5-91-1:1 structure is found to be the best fit for forecasting the AQI of Kolkata.  相似文献   

13.
全晓娟  李宁  苏波  李国玉 《冰川冻土》2004,26(Z1):115-120
In permafrost regions, many methods about active cooling embankment are put forward, one of these representations is ventilated embankment, its cooling effect is the result of the air convection in the duct, and this leads to reducing the annual average ground temperature. The present work in this article is to determine the boundary conditions of the ventilated embankment and natural ground in numerical work. There are several effects which influence boundary conditions, they are: radiation, evaporation,phase change, convection and embankment material etc. Radiation and convection are the main effects in those. We mainly consider sun radiation in this article. The added-surface effect in ventilated embankment lowers its temperature, so the temperature on the wall of the ventilated embankment is different from the temperature in atmosphere. There are two methods in determining the surface temperature, experimental method and experiential method. Detailed research is discussed in the article.  相似文献   

14.
A Stochastic Model of Transport in Three-Dimensional Porous Media   总被引：1，自引：0，他引：1  
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15.
Air pollutants can be transported to the pristine regions such as the Tibetan Plateau,by monsoon and stratospheric intrusion.The Tibetan Plateau region has limited local anthropogenic emissions,while this region is influenced strongly by transport of heavy emissions mainly from South Asia.We conducted a comprehensive study on various air pollutants(PM2.5,total gaseous mercury,and surface ozone)at Nam Co Station in the inland Tibetan Plateau.Monthly mean PM2.5 concentration at Nam Co peaked in April before monsoon season,and decreased during the whole monsoon season(June-September).Monthly mean total gaseous mercury concentrations at Nam Co peaked in July and were in high levels during monsoon season.The Indian summer monsoon acted as a facilitator for transporting gaseous pol-lutants(total gaseous mercury)but a suppressor for particulate pollutants(PM2.5)during the monsoon season.Different from both PM2.5 and total gaseous mercury variabilities,surface ozone concentrations at Nam Co are primarily attributed to stratospheric intrusion of ozone and peaked in May.The effects of the Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau are complex and require further studies.  相似文献   

16.
针对非饱和带中油类污染物时空分布的研究,室内实验很难定量分析运移机理,野外检测成本高且破坏地层。数值模拟法作为一种应用广且成熟的方法,可以用来分析油类污染物在非饱和带中的运移规律。为了研究单井抽提及原位冲洗修复时,含单裂隙非饱和带中轻非水相流体（Light non-aqueous phase liquids,LNAPL）的时空变化规律,建立了数值模型,分析不同条件下LNAPL的修复效果及时空变化规律。模拟结果发现,LNAPL注入时优先流入裂隙,停止注入时优先流出裂隙。单井抽提修复模拟表明,抽提流量越大,修复效率越高。原位冲洗技术能有效补充地下水,防止产生新的环境问题;注水井起到“冲洗”及稀释污染物的作用,模拟最优方案修复面积达到96%,修复率达到75%,LNAPL饱和度控制在约0.05;对比分析发现,注水井布设在污染物范围的上边界时修复效果最好,能有效“冲洗”污染物并携带至抽提井中抽出地表。该研究为受轻油污染的土壤及地下水修复提供了科学的理论依据及有效的评估方法。  相似文献   

17.
城市景观格局的大气环境效应研究进展   总被引：10，自引：0，他引：10  
城市规划不仅需要适应区域气候,更需要通过城市自身的合理空间配置来缓解因城市化引起的城市大气环境问题,因此,加强城市景观格局大气环境效应的研究对于提高城市规划的水平具有重要的意义。从城市下垫面的大气环境效应、大气数值模式、遥感应用技术以及城市规划的气候适应性等方面综述了城市景观格局的大气环境效应的研究进展,并分析了城市景观格局的大气环境效应应用于城市规划面临的主要问题。尽管城市景观组分的大气环境效应已经得到充分认识和应用,但是景观组分的空间组合,即城市景观格局对城市大气环境的影响及其应用研究仅仅处于起步的阶段。为了推动城市景观格局的大气环境效应研究并应用于城市规划之中,除了需要深入研究“格局影响过程”的机制外,还需要重点解决2个问题：一是寻找能够用来研究城市景观格局与大气环境相互作用的格局参数;二是确认具有一般意义的理想城市景观格局模式。  相似文献   

18.
The elemental abundances in the atmosphere of the red dwarf HD 32147, which belongs to the HR 1614 moving groups, are analyzed. The atmospheric parameters determined from spectroscopic data (the condition of equal abundances for neutral and ionized atoms of a given element) differ considerably from those derived from photometry and parallax data. The abundances of several elements are also anomalous, with the anomaly increasing with decreasing ionization potential. It is concluded that this star is a red dwarf displaying solar-like activity; i.e., having dark (cool) spots on its surface, which may sometimes be considerable in size. Modeling synthetic spectra of stars with cool spots on their surfaces, with the spectral lines consisting of two components formed in media with different temperatures, indicate that the spectroscopic atmospheric parameters derived in such cases are incorrect; this can also explain the observed dependence of the elemental abundances on the corresponding ionization potentials. This leads to the conclusion thatHD32147 is indeed a star with solar-like activity. Several other such stars considered as examples display the same anomalies as those of HD 32147. These modeling results are also valid for Ap and Am stars, and are able to explain short-wavelength observations of the Sun and some stars (the FIP effect).  相似文献   

19.
The co-location of desalination plants with existing or proposed power plants can bring forth economic and ecological advantages in terms of reducing the costs of water intake and reducing fish impingement. However, fossil fuel-based power plants are a source of ozone precursors and the added strain of power needed for the energy intensive desalination process increases these pollutants into the atmosphere. Furthermore, withdrawal from brackish water sources puts a stress on slowly replenishing aquifers. Additionally, the resulting concentrate is highly saline and disposal into ecologically sensitive bays and estuaries may be problematic. Balancing these limitations with the need for freshwater is of great importance for sustainability of water scarce arid and semi-arid regions and also requires a holistic multimedia impact evaluation. Therefore, an integrated system of systems approach is adopted in this study and a decision support system that integrates the flow of water, concentrate and resulting pollutants through two engineered (power plant and desalination plant) as well as three natural systems (coastal bay, aquifer and the atmosphere) is developed to study the co-location of a power plant and a desalination plant near the City of Corpus Christi in South Texas. The objective of the model is to minimize the amount of groundwater extraction and minimize the amount of water extracted from the bay to emphasize water and ecosystem conservation, respectively. These objectives, in turn, are subject to various other constraints including (1) conservation of mass; (2) air quality regulations; (3) salinity regulation policies; (4) groundwater management constraints; (5) water demand requirements; and (6) energy demand constraints. The results indicate that when conservation of the aquifer is weighted more, less water is pulled from the aquifer until later time periods. The salinity of the bay increases and creates a need for a greater amount of power necessary to process the saline water which, in turn, enhances the atmospheric loading of ozone precursors. Therefore, the conservation of groundwater scenario is limited by the air quality standards. Alternatively, when the goal is to conserve the ecological integrity of the bay while meeting freshwater demands, the model is bound by the prescribed drawdown constraint that limits the amount of water that can be extracted from the aquifer. The results from the study indicate that blending saline bay water with brackish groundwater and using cleaner burning fossil fuels that have limited air quality impacts will enhance the performance of the co-located power and desalination operations. The results of the study highlight the need for an integrated multimedia evaluation in assessing the feasibility of desalination in areas with marginal air quality.  相似文献   

20.
An initial investigation of recirculation is carried out for the coast of the Black Sea. The local mesoscale circulations (land-sea breezes, mountain and valley winds) in coastal areas are shown to be an additional risk factor in creating favorable conditions for air stagnation and accumulation of air pollutants in the surface atmosphere layer. Two types of annual recirculation patterns are revealed for northern and north-eastern coast of the Black Sea. Long-term changes in recirculation are investigated. It is shown that the recirculation parameter values remained quasistable until the mid-1970s. Since 1976–1977, steady intensification of recirculation in both winter and summer is identified.  相似文献   

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