基于粒径谱仪的大气PM_(10)源解析方法研究与评估

Research and Evaluation of Atmospheric PM_(10)Source Apportionment Method Based on Aerosol Size Spectrometer

本文尝试利用粒径分布数据建立一种新的大气颗粒物来源解析方法,为城市大气颗粒物解析和治理提供新思路。于2023年春季,利用大气颗粒物粒径监测仪对保定市、南阳市和鄂州市0.2、0.3、0.4、0.5、1.0、2.5、4、7和10μm共9个粒径段的颗粒物进行连续观测和来源解析,并通过沙尘过程和降雨过程对城市的粒径分布变化和解析结果进行分析和评估。结果表明:①观测期间保定市、南阳市和鄂州市总粒子数浓度平均值分别为851、755和782 cm^(−3),非沙尘期间分别为922、765和811 cm^(−3),与观测期间相比,非沙尘期间3个城市总粒子数浓度平均值均有所上升。②解析结果显示,非沙尘期间3个城市PM_(10)的首要贡献源均为扬尘源,其次依次为二次源、机动车源、固定燃烧源、工艺过程源和其他源。③在一次沙尘过程中,与沙尘前相比,3个城市在沙尘中各粒径段浓度变化均随粒径增长呈先降低再逐渐升高的特征,期间3个城市的扬尘源贡献率均显著增大。④保定市在一次降雨过程中,除PM_(2.5~4)外的其他粒径段整体表现为粒径越大浓度降幅越大的特征,其中PM_(2.5~4)可能受到湿沉降和颗粒物吸湿增长的双重影响降幅相对较小;降雨过程中扬尘源、固定燃烧源和机动车源贡献率均有所降低,其中扬尘源贡献率降幅最大。研究显示,建立的大气颗粒物粒径解析模型可以得到比较合理的PM_(10)源解析结果,有望应用于各地区大气污染治理工作中。

A new method for source apportionment of atmospheric particulate matter using particle size distribution data was established,providing new ideas for the apportionment and prevention of urban atmospheric particulate matter.In the spring of 2023,continuous observation and source analysis of particulate matter in Baoding,Nanyang and Ezhou were conducted using a particle size spectrometer,which can measure a total of 9 particle size ranges of 0.2,0.3,0.4,0.5,1.0,2.5,4,7 and 10μm.The effects of sand and dust processes and rainfall on changes in particle size distribution and source apportionment results were analyzed and evaluated.The results show that:(1)During the observation period,the average total particle number concentrations in Baoding,Nanyang and Ezhou were 851,755 and 782 cm^(−3),respectively.During non-dust periods,the average total particle number concentrations in the three cities were 922,765 and 811 cm^(−3),respectively.All three cities showed an upward trend.(2)The primary contributor of PM_(10)in the three cities during non-dust periods is dust source,followed by secondary source,vehicle exhaust source,combustion source,industrial source,and others.(3)During dust periods,the number concentrations in all three cities showed a decrease in the small size range and an increase in the large size range.And the contribution of dust sources increased significantly.(4)During a rainfall in Baoding,except for PM_(2.5-4),the larger the particle size,the greater the decline.It is speculated that the relatively small decrease in PM_(2.5-4)is due to the dual effects of wet deposition and particle hygroscopic growth.During this period,the contribution of dust source,combustion source,and motor vehicles all decreased,with the largest decrease in the contribution of dust source.The model established in this paper based on particle size can be used for PM_(10)source analysis and outputs reasonable quantitative results,and has the potential to be applied in air pollution prevention and control work in various regions.