Techniczne nauki

UDC  629.113.004.5

Methods of evaluating the influence of transport emissions on environment

 

Meirbekov A.A., Sarbasov A.S., Kushbaeva A.T., Bugenbaeva S.S.  

M.Auezov South Kazakhstan State University, Shymkent city

 

In the process of  the work of automobile accessories traking into account the information in the work of treating the level of harmful wastes in the environment the work is being conducted three operating points: in the process of cranking an engine, automobile free traffic and traffic movement. 

The level of emissions depends on the warm seasons of the year, in this case the months which have the average temperature degree below than -5º are referred to cold season of a year, and the months having the average month temperature between -5С0-and +5С0 belong to midterm seasons. In midterm seasons the degree of СО2СН and  SO2      wastes equals to 0,9 coefficient, and the degree of  NOx equals to the degree of wastes in cold season.

Automobiles pollute open air in the process of engine work as the result of emitting many types of polluting substances: nitrogen, carbon dioxide, carbon oxide, nitrogen oxide, aldehyds, hydrocarbons (ethane, methane, ethylene, benzole, propane, acetylene, toluene, xylene, butane and  others) complex aromatic hydrocarbon (pyrene, benzopyrene) soot, sulfur dioxide, hydrogen sulphide, led, manganese and etc. Nowadays more than 200 components have been found in automobile gas [1]. Great deal of these polluting substances are toxic. On the base the emission of harmful substances from the transport 15-25 % of hydrocarbons are emitted in the process of fuel evaporation in carburetor and tank. [2]

There are specific peculiarities that require to set on any level in considering this difficult problem of air pollution by transport sources. According to the employing classification they can be referred to the sources located directly in densely populated regions of the city, having variable power of throwing out harmfull substances, continuously influencing on the linear surface. These sources are caused by   emitting in air layer (less than 1 m) in low height from the earth surface of especially dangerous and defining the height of approximately 1,5 m.a great values of harmful substance concentration.

In some cases while studying concentration field from automobile sources they can be given as constant point source. Here, traffic crossroads are taken away as pollution sources, the throw outs are taken away the emissions between crossroads are regarded as surface pollution.

A high degree of characterization mainly occur in cases when pollution sources are evenly spread   in some regions respectively and traffic crossroads are considered as transport pollution sources in definite city regions , where the transport traffic flow is realized. The ratio of road length junction to the territory of the region can be used as the criterion of dividing city territory into regions. In such a case the level of polluting substances appeared from territory unit of time unit, the coordinates of the point of pollution, its height and diffusion parameters at this point are used as air pollution parameters.

 While such characterization of transport sources the alternation of wastes emission are openly less dependent on traffic.

Due to this fact it is suggested to consider all the traffic system in the city as the collection of air polluting traffic sources. The presence of length, the width of foot road, frequency of crosses, traffic organization tools and transport flow in definite city roads which are described by methods of control can be regarded as emission sources. 

The level of transport flow impact can be defined only in case if there are numerical indication of air pollution by transport sources and its toxication criteria. As the result of measures on traffic organization presented pollution index must be sensitive to the change air condition. Toxication criterion is the odd of actual pollution degree and its possible values. If there is no such an odd, then the impact of traffic condition on air pollution will be less. In case the pollution degree, according to absolute norm, exceeds the sanitary standards, its decrease is possible only due to the measures aimed at the change of the factors influencing air environment.  

Such criteria are possible if: firstly – when there are pollution degree and its change indices for this purpose; secondly – if the possible boundaries are singled out on the base of requirements for the quality of air environment connected with traffic condition of transport flow.

In definite traffic conditions the methods of getting indications with statistic value of the change of automobile sources emissions  within the time and the space should be conformed with the requirements defining quality parameters of air environment. According to the length to these measurements of transport sources the restrictments are set to the methods of experimental investigations and devices. In bench-top cases the test for toxication in automobiles is connected with the deviations proceeding from not taking into account the influence of peculiarities of physico-geographic conditions, atmospheric and microclimate conditions (the change of temperature and engine, its system state, wind, casual obstacles, etc. )

In case of numerical method of evaluating pollution sources it will be possible to differentiate efficiently the level of emitting polluting substances of car gas in connection with air quality in different city roads. For this purpose it is necessary to evaluate the norms of transport traffic, to compare it with possible norms of change of the level of decreasing the pollution degree or emitting to keep it.

It is known that the pollution degree of open air alters within the time and space. Concentration spread within the time, first of all, depends on atmospheric conditions (wind direction and speed,  temperature density stratification of atmosphere, air humidity), the height of emission sources from the earth surface. In this case heat production ability of the earth surface makes an influence on direct spread of temperature on the earth surface layer of atmosphere and it causes temperature inversion.[3] In case of inversion turbulent exchange gets lower, the disappearance of harmful substances on the earth surface layer of atmosphere gets worse. Because of increase of air temperature some harmful substances are unable to go up [4]. 

               , 

(1)

where    V – produced gas level of within the time;

                    К – exchange coefficient;

                    Т –   mixture heat temperature ;

                     - temperature gradient.

For open air pollution degree the increase of inversion with different speed of wind in state of getting higher values when there is low speed of wind, also air shutdown and humidity have great significance. The pointed factors change within a day, according to seasons in definite regions.  

Because of this fact even if there is the same emission of the level of earth surface proximate concentration of harmful substances emitted from auto cars the atmosphere changes depending on atmospheric conditions. These atmospheric conditions influence on the processes of transformation, the disappearance of main ingredients of auto car emissions, self cleaning of the atmosphere layer close to the     earth surface. Mainly the followings are referred to atmosphere self-cleaning:

-                     production of substances having a low reaction power (solids, stack ash ) because of force of gravity 

-                     the dissolution and connection of harmful emissions as gas in an open air because of solar radiation.

A definite part of self cleaning of environment, namely atmosphere is connected with absorbing approximately 50% of technogenic  СО2 emission of world ocean.  Moreover, chemical elements  and compounds in the atmosphere absorb a part of sulfur, nitrogen, gaseous compounds of carbons, also, self cleaning process actively takes place with green plants. Also an atmospheric rainfalls presented in the 1st  table influence on this process.

Polluting substances that get into atmosphere from transport reacting with biosphere components and between each other make new substances.

 

 1-table

The influence of rainfalls on soot concentration in

Level of rainfall, мм

Soot concentration, мg/м3

0 – 1

0,123

1 – 5

0,112

5 and higher

0,098

 

The level of mixtures settling on the surface depends on density stratification, wind speed and other characteristics of the earth surface. Therefore, the influence of surface and mixture should be taken into consideration as the influence of the earth surface.  

Besides, it should be taken into account that the activeness of atmosphere self cleaning process is lower than technogenic pollution, including transport pollution.  .

Weather conditions (wind speed and direction, air temperature, humidity and pressure), landscape peculiarities, day time, the location and characteristics of surface layer and others influence on To the dispersion of harmful substances

 

                                                              Literature

1.            Akimova Т.А., Khaskin V.V.. Ecology, Textbook for HEIs. - М.: UNITY-DANA, 2002. - 566 p.

2.            Lukanin V.N.., Buslayev A.P.., Trofimenko Yu.V., Yashina M.V.. Transport flows and environment. Textbook for HEIs / under edution of . V.N. Lukanin. - М.: INFRA-M, 1998. - 408 p.

    3.   Israel Yu.A.. Ecology and environment state control Экология и контроль состояния природной среды. - М.:   Hydrometedition, 1984. -297p.                                                                                                              

4.  Development of research methods of  spread processes, transformation in atmosphere of car combustion gases. / SRW report. - L.: IPTRAN, 1991. - 49 p.

 

 

 

Резюме

            Приведен анализ основных (природных и техногенных) факторов распространения загрязняющих веществ в атмосфере. Выявлены степень влияния метеорологических и географических условий на  распространение и трансформацию автомобильных выбросов в окружающую природную среду. Уровень приземной концентрации вредных веществ от автотранспортных средств при одном и том же  массовом выбросе может существенно меняться. Это в зависимости от метеорологических условий, размера территории, на которой осуществляется загрязнение  и уровня техногенного освоения территории.  А также, темп  скорости  самоочищения атмосферы, наиболее ниже  техногенныe  загрязнении,  в том числе транспорта.

 

Summary

           The analysis of the basic (natural and technical) factors of distribution of polluting substances in an atmosphere is resulted. Are revealed a degree of influence of meteorological and geographical conditions on distribution and transformation of automobile emissions to surrounding natural environment.

The level of ground concentration of harmful substances from vehicles at the same mass emission can vary essentially. Depending on meteorological conditions, the size of territory on which pollution and a level technical development of territory is carried out.  Also, the tempo of speed of self-clearning of atmosphere more lower of techno-gene and transport.