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Lanzhou University (2022)

Source Appointment of Fine Particulate Matter and Its Absorption of A Typical Basin City in the Northwest Semi-arid Region

王敏

Titre : Source Appointment of Fine Particulate Matter and Its Absorption of A Typical Basin City in the Northwest Semi-arid Region

Auteur : 王敏

Grade : Master 2022

Université : Lanzhou University

Résumé partiel
Various pollution sources in cities bring atmospheric particulate matter,especially fine particulate matter,through primary emissions and secondary generation processes,which both directly pollute the environment and affect the weather and climate through radiation processes,and have significant impacts on human health,economic development and other aspects,it is very important to quantitatively estimate the sources of pollutants.Along with social and economic development and changes in production and lifestyle,the sources of fine particulate matter have been constantly changing.Since the implementation of China’s air pollution prevention and control action plan in 2013,source appointment results from Chinese cities have shown a significant decrease in industrial emissions and an increase in vehicle emissions,and vehicle emissions have become an important cause of visibility reduction under unfavorable weather conditions in some cities.As a typical river valley basin city in the semi-arid region of northwest China,the source appointment results of fine particulate matter in Lanzhou are mainly based on the more polluted years of 2012—2013,and there are few studies on the source appointment of pollution under the reduced pollution scenarios after 2013,and the influence of unfavorable dispersion conditions caused by the closed topography of Lanzhou on the source appointment needs to be further clarified.Most of the existing studies are based on off-line analysis and daily variation information is not fully considered.At the same time,the rapid decrease of atmospheric single scattering reflectance with the increase of pollution in Lanzhou also puts new demands on the source appointment.To address the above-mentioned problems,this paper uses hourly resolution hourly online data of PM2.5,organic carbon(OC),elemental carbon(EC),water-soluble ions and elements from December 2019 to November 2020,a positive matrix factorization model(PMF)and a multiple linear regression model,considering the characteristics of typical river basin cities in the northwest semi-arid region,including the conditions of unfavorable dispersion and source appointment,absorption enhancement and source appointment,etc.The source appointment of PM2.5 and absorption coefficient were carried out separately,and the contribution of vehicle emission sources to fine particulate matter in typical basin cities in the northwest semi-arid region was given,and the main pollution sources affecting the absorption coefficient were obtained.The main results and conclusions are as follows.(1)The most serious pollution was found in Lanzhou in winter,with PM2.5 mass concentration of 72.8μg·m-3 and Organic Matter(OM)and Secondary Inorganic Aerosols(SIAs)as the most important components.The PM2.5 mass concentrations were 39.2,24.3,and 43.6μg·m-3 in spring,summer,and autumn,respectively,during the study period.The percentages of OM and SIAs decreased with increasing pollution in spring and summer,and the percentages of SIAs decreased with increasing pollution in winter,while OM was stable at about 40.0%.

Mots clés : PM2.5 ;hourly resolution ;source appointment ;vehicle emission ;absorption;

Présentation (CNKI)

Page publiée le 24 octobre 2022