Pollution Characteristics Of Inorganic Elements In Atmospheric Particulates In Xi'an And Preparation Of XRF Standard Filter

Since the reform and opening up,China's development has been changing with each passing day,and many pollutants have emerged.Air pollution has always been attended to by China and other countries in the world.In recent years,air pollution in Xi'an has become more and more serious.Inorganic elements,especially heavy metals,are adsorbed on fine particles and stored in the body for a long time,which is very harmful to the human body.X-ray fluorescence spectroscopy?XRF?is an important means for analyzing inorganic elements because it does not require pre-treatment during particle analysis and achieve non-destructive requirements during sample analysis.In this paper,XRF was used to study the pollution characteristics and source distribution of inorganic elements in atmospheric particulates in Xi'an.Considering that the standard membranes used in this method are all imported,the difference in matrix will cause the difference of analysis results and the price is expensive.In this experiment,the standard membrane?GSS-25?is used to prepare the standard membrane by sampling with the particle resuspension sampler.The main contents include:?1?Introduction.This chapter introduces the composition and source of atmospheric particulate matter,expounds the hazards of PM2.5 and PM10,the hazards of heavy metals in inorganic elements,the advantages and applications of XRF analytical methods and the preparation methods of standard samples,the research significance and main contents of this paper are proposed.?2?Pollution characteristics of inorganic elements in atmospheric particulates in Xi'an City.This chapter analyzes the seasonal pollution characteristics of inorganic elements by taking PM2.5 and PM10 in the atmospheric environment of Xi'an as the research object.The results show that in the spring,summer and autumn,the element content?except S,Zn,Ba,La?in PM2.5 is lower than that in PM10,mainly concentrated in coarse particles,and the opposite is true in winter.Al,Ca,K,Fe,Zn,Ba,Si,S and Cl are the main pollutants in the four seasons.According to Pearson correlation,the source of Cl has a great relationship with biomass burning and waste incineration.The sources of Fe,Mn and S elements are closely related to construction activities.Ba is likely to be derived from the burning of garbage in daily life.It is highly unlikely that S and Cl will have the same source.?3?Research on the performance index of Particle resuspension sampler?PSS?.The particle resuspension sampler is used as a standard filter preparation equipment,and its performance index is discussed by the background value of the resuspension box,air tightness and parallelism of the collected samples.The results show that the concentration of particulate matter in the resuspension tank is very small,and the particle size of 0¹?m is mostly,and the influence on the quality of PM2.5 and PM10 is negligible.The flow rate during the sampling process is maintained at 16.67 L min^-1.The pressure variation of the four channels is very small,which is in a stable state;the maximum relative error of the same particle size PM2.5 and PM10 filter loading is 3.4%;The maximum relative standard deviation of the PM2.5 and PM10 filter loadings of different membrane sizes was 0.36%.Therefore,the sampling volume of the four channels of the instrument has good parallelism and can meet the requirements for preparation of standard filter membranes.?4?Preparation and application of standard filters.The consistency between the measured value and the theoretical value of each element,the stability of the filter membrane,the precision,and the measurement result and standard value of the actual sample are the reliability of the standard filter prepared by the test was evaluated.The results showed that The correlation coefficient between the measured value of and the theoretical value of Na,Mg,Al,Si,K,Sc,Ti,Ca,V,Cr,Mn,Fe,Ni and Zn in PM2.5 and PM10 of the teflon filter is greater than 0.99;except for Zn,the precision of other elements are within the precision requirement of HJ 829-2017;The test value of the commercial film to the actual sample is a standard value.When the confidence is 99%and 95%,the t values of Si,Ca,Fe,Ni,and Zn are smaller than the t-table.In summary,it can be concluded that the measured values of Si,Ca,Fe and Ni in the standard filter are in good agreement with the theoretical values,and the precision is high,and the test values and standard values of the actual samples are not significant.Sexual differences can be used for the testing of actual samples,so in the future this method can be used to prepare XRF standard filters.