城市大气颗粒物背景值涵义及定值方法

城市大气颗粒物背景值的概念对防治城市大气颗粒物污染具有重要意义。城市大气颗粒物背景值不同于颗粒物本底值。本底值是指不受人类活动影响的自然条件下颗粒物的浓度值,而背景值是个相对值,其所在的环境条件有可能已经受到了环境污染。影响城市大气颗粒物背景值的因素主要包括两个方面:一是污染源,主要包括城市本地源排放和外来颗粒物,二是颗粒物扩散的天气和气象因素。将城市大气颗粒物的背景值定义为在一定时期内,由于城市本身的排放,城市大气环境中颗粒物的浓度水平。通过分析总结近年来人们对大气颗粒物垂直分布规律的研究,探讨了采用监测一定高度处大气颗粒物,结合气象因素确定城市环境空气中大气颗粒物背景值的方法。

Definition and Determination of Urban Air Particulates Background Value

The background value of urban air particulate matter is of great importance for preventing the urban air pollution.It is different from the natural background value which is the concentration of particles in the natural conditions without human impact,whereas the urban background of particulate matter is a relative value,the environment it exists may have been impacted by human activities.There are two major aspects affecting the urban background value of particulate matter.One is pollution sources,include local urban sources and outside particles;the other is weather and meteorological factors.In this study,the urban background of particulate matter can be defined as the particle concentration which is mainly impacted by local sources in a period of time.After analyzing the vertical distribution characteristics of particles in recent years,the method through monitoring the concentration of particles at certain height and combining with the meteorological factors can be adopted to calculate the urban background value of particulate matter.