Font Size: a A A

Characteristics Of Atmospheric Particulate Matter Mass Concentration,number Concentration And Particle Size Distribution In Urban Areas Of Zhengzhou

Posted on:2023-07-29Degree:MasterType:Thesis
Country:ChinaCandidate:B Y HuangFull Text:PDF
GTID:2531306623475084Subject:Environmental Science
Abstract/Summary:PDF Full Text Request
In recent years,the rapid urbanisation and industrialisation in China has caused serious atmospheric particulate pollution.The mass concentration,number concentration and particle size distribution of atmospheric particulate matter can not only reflect the source of particulate matter,but also influence the duration of its presence in the atmosphere,with implications for atmospheric photochemical reactions,climate change and human health.The Zhengzhou city is one of the most polluted cities in China,and previous studies have mainly analysed the mass concentration of atmospheric particulate matter,but further in-depth investigation of the number concentration and particle size distribution is urgently needed.In this study,the mass concentration,number concentration,and size distribution of atmospheric particulate matter were measured from January 2020 to January 2021 using the electrical lowpressure impactor(ELPI+).Their characteristics were investigated in different seasons,typical weather scenarios in winter,and the COVID-19 epidemic in 2020.Moreover,the PM2.5 chemical components and sources were studied in the COVID-19 epidemic to provide typical scenarios and data support for the development of air pollution reduction strategies.The main findings are as follows:(1)The mass and number concentrations of PM2.5 were highest in winter and summer respectively.The mass concentrations were mainly concentrated in the particle size range above 0.108 μm and the number concentrations were mainly concentrated in the particle size range below 1μm.The diurnal variation of PM2.5 mass concentration was significantly influenced by the accumulation mode(0.06~1.6μm).The diurnal distribution of the accumulation-mode particle showed a single-peak in spring with a peak at 8:00.,a single-peak distribution in summer with a peak at 8:00.,and three-peak distribution in winter with peaks at 9:00.,13:00,and 23:00,respectively.The diurnal variation of PM2.5 number concentration was significantly influenced by the nuclear mode(0.006~0.06 μm).The diurnal distribution of the nuclear-mode particle showed bimodal distribution in spring with peaks at 8:00 and 20:00,a single-peak distribution in summer with peaks at 12:00,three-peak distribution in autumn with peaks at 6:00,11:00,and 20:00,and bimodal distribution in winter with peaks at 8:00 and 19:00,respectively.(2)The rainfall process could remove the atmospheric particulate matter with particle sizes ranging from 0.108 to 2.5 μm,and the mass and number concentrations of particulate matter with a particle size of 1 to 2.5 μm are most significantly reduced by rainfall.Sandy weather could contribute to an increase in the mass concentration of atmospheric particulate matter with a particle size above 0.108 μm and the number concentration of atmospheric particulate matter with a particle size above 0.17 μm.(3)Haze pollution processes still occurred during the COVID-19 epidemic control period in Zhengzhou city.The results of the data analysis indicated that the increase in the mass concentrations of particulate matter with particle sizes ranging from 0.4 to 1.6μm and the number of atmospheric particles with particle sizes ranging from 0.4 to 1μm were the main factors for the haze formation.The chemical component indicated that PM2.5 was mainly derived from secondary particulate matter.The source analysis showed that COVID-19 epidemic control measures could effectively reduce the contribution of motor vehicle sources,industrial sources,and combustion sources.The results of backward trajectory clustering and potential sources indicated that PM2.5 was significantly influenced by regional transport between Zhengzhou city and the surrounding areas,and the epidemic control measures had reduced the influence of transport from local and surrounding areas.However,unfavourable meteorological conditions have led to hazy and polluted days during the COVID-19 epidemic control period in Zhengzhou city.In summary,this study investigates the variation patterns of the mass concentration,number concentration,and size distribution of atmospheric particulate matter and finds the results that the rise in mass concentration and number concentration of atmospheric particulate matter with particle size between 0.4 and 1μm and the secondary reactions in the atmosphere contribute significantly to haze pollution in Zhengzhou city,which provides data support for the government to establish pollution reduction measures.
Keywords/Search Tags:Zhengzhou city, Atmospheric particulate matter, PM2.5, Mass concentration, Number concentration
PDF Full Text Request
Related items