Hava kirliliği modellenmesi ve Gebze için SO2 azaltım stratejilerinin incelenmesi

Abstract

Gelişen teknoloji ile birlikte Gebze'de de büyük ilerlemeler olmuştur. Köyden şehire göçün son yıllarda oldukça fazla olması, yeni sanayi sektörlerin kurulmasına neden olmuştur. Hızla artan nüfus yoğunluğuna paralel olarak konut sayısı da bir artma göstermiştir. Konutların ve ticaret merkezlerin yer seçiminde bölgenin coğrafik ve meteorolojik etüdünün yapılmaması, çarpık kentleşme durumu ortaya çıkarmıştır. Bu durumda Gebze1 de de hava kirliliğine neden olan faktörler oluşmuştur. Bu çalışmada; hava kirliliğine neden olan etkenler alan ve nokta kaynaklar bazında değerlendirilmiştir. Bu amaçla pilot bölge olarak seçilen Gebze'de hava kirliliğini etkileyen nüfus, yakıt tüketimi, endüstriyel üretim ile meteorolojik veriler derlenmiş ve yakıt tüketimi EPA onaylı "Endüstriyel Kompleks-Uzun Dönemli Dağılım Modeli (ISCLT)" ile modellenmiştir. Bu tüketim talebinin karşılanabilmesi için alan kaynaklarda yakıt tüketimi için üç ayrı senaryo belirlenmiş ve nokta kaynaklarda ise ya kıt değişiminin sabit olduğu varsayılmıştır. Bu senar yolar; Sama linyiti ve doğal gaz yoğun tüketim seçenekleri içermektedir. Model sonuçlarına göre emisyon miktarları; doğal gaz için 17 ug/m3, Şoma linyiti için 3D ug/m3 bulunmuş tur.

Air pollution is woven throughout the fabric of our modern life. A by-product of the manner in which we build our cities, air pollution is waste remaing from the ways we produce our goods, transport ourselves and our goads, and generate the energy to heat and light the places where we live, play, and work. The major cause of all air pollution is combustion. When perfect or theoretical combustion occurs, the hydrogen and car bon in the fuel combine with oxygen from the air to produce heat, light, carbondioxide, and water vapour. However, impurities, in the fuel, poor fuel-to-air ratio, or too high or too low combustion temperatures cause the formation of such side products as carbonmonoxide, sulfur oxides, nitrogen oxides, fly ash, and unburned hydrocar bons-all air pollutants. The sources of pollution are typically classified into the following five categories: 1- Fuel combustion in stationary source: The first category includes all facilities where fuels are burned to provide either space or process heating. All fuels- coal, cokes fuel oil, gas, and wood-dontribute in varying degrees to total emissions. In must areas, the burning of these fuels accounts for the majority of sulfur oxide and partuculate emissions. Sources in category can be further subdivided according to the type of consumer; a- Steam-electric power plants, b- Industrial facilities, c- Houses and apartment bulidings, d- Commercial, institutional, and governmental bulidings. VI 2- Mobile sources: This category includes road vehicles, vessels, trains, and aircraft. The fuels of primary corcern are gasoline and diesel fuel used by motor vehicles; diesel oil, and coal burned in locomo tives and vessels; and aviation fuels in aircraft. Carbonmonoxide, oxides of nitrogen; hydrocarbons, and particulates are pollutants of primary interest from this category of sources. 3- Industrial processes: This category includes all facilities that generate pollutants during the manufac ture or handling of products, other than the pollutants emitted from the use of fuels. k- Disposal of solid waste: This category consists of the incineration or open burning of solid waste which can be a significant suorce of pollution. Such burning may take place either in large central facilities, such as municipial incinerators and open-burning dumps or at individual residences, factories or shops. 5- Evaporation of organic substances: Included in this category is the evaporation of gasoline, points and dry cleaning solvents. Emissions, air quality and meteorological data provide the basic information for understanding an area's air pollution problem. The accounting of air pollutant sources and their related emission rates for a given area is defined as an "emissions inventory". Although many different procedures are available for compiling an emissions inventory, all of them depend on the use of average "emission factors", since it is impractical to measure continuously, or even periodically, the discharges of pollutants into the atmosphere from all sources. Emission factors have been formulated for most of the major types of sources. The multide of sources in urban areas can be further classified according to emission rates. Sources that individually contribute significantly amounts of pollutants deserve special attention; in most inventories are considered seperately as "point sources". Typically these include power-generating stations, central incine rators and large industrial concerns. Sources that indi vidually do not contribute significant quantities of pollutants are considered jointly are "area sources"; typical of these are automobiles, houses and small indust ries. vix The emission af sulfur compounds into the atmosphere has developed into one of the major pollution problems of the late 196Ds. The interest in airpollution in centered olmost exclusively on the emission of SO,-,. Sulfur dioxide and sulfur trioxide are the dominant oxides of sulphur present in the atmosphere. Sulfur dioxide is a nonf lammoble, nan explosive, colorless gas that couses a toste sensation at concentrations from 0.3 to 1.0 ppm in air At concentrations ahove 3.0 ppm the gas has a pungent, irritoting odor. Sulfur dioxide is partly converted to sulfur trioxide or to sulfuric acid and its solts by photochemical or catalytic processes in the atmosphere. Sulfur trioxide and moisture form sulfuric acid. The oxides of sulfur in combination with carticulate and maisture produce the most domoging effects ottributed to atmospheric air pollution. Unfor tunately, it has proven dificult to isolate the effects of sulfur dioxide alone. Adverse effects of S0" emission was first observed in early 1950's. In the surface waters in the indust rial Ruhr area of Germany. The catastrophic air pollu tion in London in 1952, which caused as many as 4000 deaths within a few day, was attributed to the high S0" concentration in the atmosphere Acid rain results from oxidation of S0" to SO, in the atmosphere and the reac tion with HpO to yield sulfuric acid. This formation is catalysed by NO and sun light. Acid rain is especially very harmfull on the coniferous forests. It causes browning and loosing of pine needles and decreases resis tance of trees, resulting in death of the plants. Winds often carry S0" emissions over long distances and cause harmfull effects of location very for from the source af the emission. No other pollutent has been studied as intensely as the oxides of sulfur, yet many questions concerning effects of sulfur dioxide upon health remain unanswered. Because sulfur oxides tend to occur in the same kinds of polluted atmosphere as particulate matter and high humidity, few epidemiologic studies have been able to differentiate adequately the effects of the pollutants. As the problem of:S0" pollution grows up the deter mination of pollutant long-term becomes important. In this study, industrialized Gebze was chosen as plot region and long-term S0? control strategies were examined, For this reason, emission inventory was rpepared by con cerning meteorological and topographical factors by using ISCLT program. Vlll Industrial source complex Dispersion model (ISCLT) is is one of the many computer softwares developed by Trinity Consultant inc. The program is designed to estimate pollutants concentrations or depositions from any combination of point, area or volume sources. The program is divided in to sequence of operation and a series of eight files are created by three individual packages of the program. The sequence of operations are shown in Figure 1. A source data (.PNT) file is created by the ISCLT when the source data is entered. The meteorological data is stored in a "Star" summary file (.STR) which contains the annual average frequency distribution of stability and wind speed combination for up to 16 mind directions. All the data needed for the model dun is contained in a data file (.DAT). All three data files (.PNT, STR., DAT) is required when the model program runs and the result is written to a list file(.LST) which contains all the input information and the calcu lated concentrations or depositions at each receptor point. Breeze Air Graphic & Surfer is again a menu driven system and allow to create 2-dimensional and 3-dimensio- nal plot from an input files. A raw graphic file (.RAW) is generated by the ISCLT model during the ISCLT run. Useful information is extracted from the raw data file by the Breez Air Graphic program and is written into an input file (.INP). This input file contains the calcu lated results and coordinates of the receptors in a X,Y,Z format, and use to generate a grid file (.GRD) which records the results and the receptors in gridded format. Topo program from the surfer graphic package, which is developed by Golden Software Inc, USA, is used to create 2-D contour map and surf program is used for the 3-D surface plot. Both the Topo and Surf program saves the date in a plot(.PLT) file which can be printed out by a printer or a platter. The ISCLT is steady-state Gaussian model, incor porating monthly, seasonal or annual frequency distribu tions of wind speed, with direction and stability, cata- gory, and is used to assess pollutants concentrations/ depositions from a wide variety or sources associated with a industrial source complex. IX .STR File.PNT File.DAT File r Extrect Data Points.INP File FIGURE 1. The Sequence of Operations As shown in Table 1., if the household fuel is changed the amount of S0" emission shows a decrease of 66-81 % according to the present situotion. TABLE 1. Amount of S02 Emission Based on A,B, Scenarios Scenario Fuel Amourt of SD^ Emission (ug/m3) Present Situation - 88 A Natural Gas 17 B Lignite (Soma) 30