Study On The Uncetrainty In Source Apportionment Of Particulate Matters In Urban Atmosphere

The urban atmospheric pollutants mostly exist as two forms of gaseouspollutants and aerosol pollutant. Aerosol pollutants are also called particulatepollutants. It refers to a relatively stable suspension system which is formed of tinyparticles of solid or liquid evenly distributed in gas. The total suspended particulatesare all the non settleable particles of solid and liquid suspending in the urbanatmosphere with a diameter of less than100μm. The main source of TSP involve thesmoke generated by fuel combustion, the dust caused in production process, buildingdust and construction dust, traffic dust, soil and sand dust and particulate pollutants ofsaline formed by gaseous pollutants with complex physical and chemical reactions inthe air.According to the particle size, particulate pollutants in the urban atmosphere canbe divided into TSP, PM10, and PM2.5, with the following inclusion relations of TSPcontaining PM10and PM10containing PM2.5.PM10is called respirable particulate matter or floating dust, and its main sourcesare emission of chimney and car exhaust and fine particles formed by some physicaland chemical effects. With the deepening research on atmospheric particulate, PM10isthe most harmful to environment and human health in the category of all particulatematter. It can enter human respiratory system, and even penetrate the alveoli and enterthe blood circulation to influence the heart and brain and other vital organs, then itwill pose a serious threat to life and health. The aerodynamic diameter of PM2.5is below2.5μm. It is also called fineparticulate matter or particulate which can into the lungs. Although the content ofPM2.5in atmospheric composition is small, then compared to other larger sizeparticles, it has some characteristics, such as small particle size, much toxic andharmful substances contained, staying in the atmosphere in a long time, a fartransmission distance, etc. It has important influence on quality and visibility of urbanambient air.From the history of the development of TSP pollution and control, China beganto attach importance to the research of particulate matter pollution in the early1970s.In recent years, many cities and regions put a lot of manpower, material and financialresources into the control of dust pollution, but the atmospheric particulate matterpollution is still very serious. Most of northern city's TSP average concentration valueof0.3~0.5mg/m3, which is1.5to2.5times higher than the national secondarystandard of0.2mg/m3, and it is much higher than the lowest average concentration of0.11~0.18mg/m3that may affect the human body. State of the Environment in2010showed that urban air quality is generally good and has improved over the previousyear, but in some cities there is still a very serious pollution.The review showed that recently domestic airborne particulate matter sourceapportionment research focused on the case studies on different regions, differenttimes and different methods and so on. Overview of the existing research resultsfound that by the impacts of original data error, resolve methodological differencesand many non-sources pollution factors, it will cause the uncertainty of the analyticalresults, reduce the comparability and accuracy of source apportionment results.Therefore, it is necessary to in-depth to explore a variety of uncertainties in theprocess of atmospheric particulate matter source apportionment.This paper chose Longyan in Fujian Province as the study area, and chose theresearch of atmospheric respirable particulate matter (PM10)source apportionment asthe basic material. By qualitative and quantitative study of the various uncertainties, itprovided a scientific basis for control and related decision on urban air particulatematter pollution. It studied mainly from the following three aspects: the quality assurance of the original data, the choice of source apportionment methods, as well asthe factors of non-pollution sources. From the above aspects it in-depth studied theuncertainty of urban atmospheric particulate matter source apportionment research.Specific studies are as follows.1. The quality assurance of the original dataIt mainly includes two aspects:(1) since the sampling time of sourceapportionment is shorter compared to the routine monitoring, in order to evaluate thetypical and representative of the samples, we mainly use statistical analysis methodsto evaluate and analyze the consistency of sampling results on source apportionmentand urban air automatic stations over the same period;(2) since the errors in thesampling and analysis of the source apportionment will affect the accuracy andprecision of the original data for source analytical calculation, we mainly use the fullquality control model to study the reasonable of the sampling variance, analysis ofvariance and geographic variance, to ensure the accuracy and precision of the originaldata.2. The compare of source apportionment methodsThere are many options in source apportionment studies, and the data need, theresolution process and the analytical results in different methods will be different.Three typical analytical methods were chosen in this paper to have a comparativestudy, including the chemical mass balance model (CMB), factor analysis (FA) andthe positive matrix factorization method (PMF).3. Factors of non-pollution sourcesBy a comprehensive comparative study of source apportionment case, it showedthat the concentration of particulate matter in urban atmospheric environment changednot only affected by the combined effects of various types of pollution sources, butalso contacted with the topography and climate conditions in research area. And evenin the same research area, the sources of pollution in different periods will have asignificant difference. In source apportionment studies, these factors might cause aconsiderable impact for the ultimate source contribution rate, so that it should be given enough attention. These contents are fully reflected in the case studies in thispaper.This thesis accepted the funding from Longyan City Project of "atmosphericrespirable particulate matter source apportionment in Longyan", and chose theuncertainty of the source apportionment of urban atmospheric particulate matter as astarting point, to explore the uncertainties of the three aspects in urban atmosphericparticulate matter source apportionment study. They are: the meeting of original datafor quality assurance requirements, the difference between different sourceapportionment methods, as well as the factors of non-pollution sources on sourceapportionment.The results show that there are a lot of uncertainties in the urban atmosphericparticulate matter source apportionment studies, and these uncertainties will impactthe results of the source apportionment, leading to biased source apportionmentresults. This paper summarized the above three typical uncertainty issues, andproposed appropriate solutions. The results of this study can be used as the theoreticalguidance and the object of case analysis in related research.This paper has two innovations:1. The application of Total Quality Control Model (SAX) is chosen to the wholequality control on the sampling and analysis process of the source apportionment forthe first time in the urban atmospheric particulate matter source apportionment;2. It proposed to consider the impact of non-pollution sources to the sourceapportionment for the first time, which including geology and geomorphology,climate meteorological and pollution periods, etc.