| The organic carbon in the fine particles of the atmosphere has a particularly obvious impact on the health and life of the human body.Therefore,studying the chemical composition,distribution law and source analysis of the fine particles in the atmosphere is of great significance for understanding the regional and urban air pollution conditions and controlling the pollution of particulate matter.Atmospheric organic pollution is an important factor affecting urban air visibility and human health.This study analyzed the one-year Shanghai PM2.5 sample from 2016to 2017.The WSOC in the sample was analyzed by TOC instrument,and the organic matter in the sample was analyzed by LC-MS.The seasonal distribution characteristics of WSOC in the PM2.5 season,the correlation between WSOC and ions,gaseous pollutants and elements,and the relationship between WSOC and ions,gaseous pollutants and elements in the day and non-ash day,and samples were also analyzed.Organic matter in the medium and analysis of the source of WSOC.This study has the following conclusions:?1?During sampling,the mean values of WSOC and IC were 3.53?g/m3 and 0.12?g/m3,respectively.Compared with other cities in the country,although at a relatively low level,it is higher than developed cities.The seasonal variation of WSOC appears as:winter>autumn>spring>summer,and the reason is caused by the difference of different meteorological conditions and the change of pollution sources.?2?WSOC and O3 have a good positive correlation in summer and winter,but negative correlation in spring and autumn;WSOC has good correlation with Na+and NO3-in summer,but WSOC and other ions do not R2 The good linear relationship is not obvious,which may be due to the complicated source of WSOC.The correlation between WSOC and Al,Cr and Mn is better in spring,and WSOC is relatively burned by motor vehicle exhaust and fossil fuel.In summer,WSOC has a good correlation with As?Cr?Cu and Zn,indicating that WSOC is mainly contributed by motor vehicle exhaust and fossil combustion in summer.?3?During the ash day,WSOC is positively correlated with O3,indicating that WSOC is partly derived from secondary conversion;and during non-ash days,WSOC.SO2,Na+,NH4+,SO42-,NO3-,and Nss-K+all showed positive correlations,indicating that the main source of WSOC was affected by agricultural production,coal combustion,and vehicle exhaust.Throughout the whole,WSOC,IC,TC,O3,V elements,etc.,PM2.5,elements and ions during the ash day are greater than the non-ash day.Among them,WSOC may be mainly due to the relatively active photochemical reaction on non-ash day,resulting in relatively more secondary organic carbon.?4?By screening the mobile phase,screening the mobile phase itself,the number of ultrasonic waves,the screening of the extractant,and the comparative analysis of the sampling membrane,we adopted appropriate conditions and obtained the mass-to-charge ratio of 484.4?528.4 by the two-stage mass spectrometry.The substances of572.4 and 163.1 are then combined according to manual deconvolution and database desorption to obtain functional groups which may be contained in these substances,such as hydroxyl,amino,ether bond,ketone bond,etc.,and the parent ion error and matching are strictly controlled.Rate error.A total of 41 substances were tested by a combination of high-rate time-of-flight mass spectrometry and mass spectrometry databases.However,due to conditions,they were not tested for standard samples,so they could only exist.The types of substances detected are organic acids,phenols,lipids,ketones,etc,which are consistent with the existing literature.?5?Using SPSS as the principal component factor analysis,the source analysis of water-soluble organic carbon,t and soluble ions and elements in PM2.5 of Shanghai was carried out.It is concluded that WSOC mainly comes from secondary conversion,biomass burning and building dust. |
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