Study On Characteristics Of Atmospheric Particulate Pollution In Tianjin

This paper used the atmospheric vertical observing platform for tethered balloons and ground monitoring equipment.In November and December 2016,vertical observations and ground observations were conducted on atmospheric particles in the atmosphere of 20-1000 meters in Gaocun,Tianjin.First of all,this paper comprehensively analyzed the vertical distribution characteristics of atmospheric particles on different pollution degree days.Then,based on the ground data,the vertical distribution characteristics of atmospheric particulates during a typical heavy pollution process were analyzed.At the same time,the particle distribution in the vertical direction of every time lift the ball was stratified according to the number concentration of particulates.This paper also used the HYSPLIT back trajectory model and GDAS airflow data to track and analyze the pollution sources of heavy pollution days.Finally,the ground sampling film during the Gaocun winter observation in Tianjin was analyzed and a simple source analysis was performed.The main conclusions of this paper were as follows:(1)The vertical distribution of number concentration of atmospheric particles in different degrees of pollution had the phenomenon of stratification.The order that from more to less of the stratification was mild pollution days,heavy pollution days,moderate pollution days and clean days.Temperature and humidity had a greater influence on the number concentration of particulate matter and should be considered comprehensively.(2)The average particle spectrum of different degrees of pollution days showed a unimodal distribution with a peak particle size of around 0.7?m.Observed particles were mainly fine particles with a particle size of less than 2.0?m.The width range of particle detected by atmospheric particle spectrometry was "heavy pollution days>clean days>moderate pollution days>mild pollution days".(3)On heavy pollution days,the source of atmospheric particulate pollution was mainly local source emissions.Motor vehicle exhaust gas,bulk coal combustion,surface dust and agricultural activity emissions were the main reasons for the high concentration of particulate matter in Gaocun,Tianjin.The backward trajectory showed that the gas block on the northwest by west path also contributed to air pollution.(4)Under a typical heavy pollution process for two days,the number concentration of particulate matter on the first day showed a trend of increasing first and then decreasing with the increase of altitude.On the second day,the number concentration of particulate matter showed a tendency of decreasing with the increase of altitude.The maximum number concentration for each altitude corresponded to a particle size of approximately 0.777um.The particle size spectrum of the morning 3rd lift,afternoon and evening lift presented three concentration stratifications and two concentration stratifications appeared in the morning for the first lift.In the morning for the first lift,the maximum number concentration of the particle size spectrum(up to 498/cm3)was higher than the rest of the day.There was little difference in the maximum number concentrations in the morning,afternoon and night lift.Two-day particle size distribution showed a unimodal distribution.(5)The backward trajectory of a typical heavy pollution process found that the heavy pollution on the first day was come from Shanxi and Hebei regions.The preliminary judgment of the source of pollution on this day was mainly from factory emissions and coal combustion.The source of the gas block on the second day of pollution was the northwest direction.The source of the gas block was located in Inner Mongolia,and heavy pollution would end.(6)After analysis of the surface sampling membrane source,the mass concentration of major elements was high during the period from December 1 to December 20.The average concentrations of Si,Ca,Al,Fe and K were higher than those of other elements.These five elements were the main elements of Gaocun winter sampling film.Contacted with local conditions,the main source of pollution in winter of Gaocun may be surface dust,metallurgical chemical dust and garbage incineration and so on.At the beginning of December and December 19,the ion concentration was high.NO3-,SO42-,NH4+ and Cl-were the main ions in winter.The concentrations of these four ions were much higher than that of other ions.Contacted with Gaocun winter conditions,ion pollution mainly came from heating and burning,motor vehicle exhaust and agricultural activities.