The Speciation Distribution,source Analysis And Risk Assessment Of Arsenic And Antimony In PM₁₀ And PM_2.5 In The Northeast Of Chenghua District,Chengdu

PM₁₀ and PM_2.5 are known as inhalable particles and particulate matter that can enter the lung,respectively.The increase in the concentration of these fine particles will cause a significant increase in morbidity and mortality.Arsenic is classified as a category 1 carcinogen by the World Health Organization's International Agency for Cancer,and antimony and its compounds have been given priority by the U.S.Environmental Protection Agency and the European Union.The thesis aims at the lack of or insufficiency of the original speciation analysis methods of the atmospheric particulate matter of arsenic,antimony and other elements,the research area and the research content,taking PM₁₀ and PM_2.5 as the research objects in the spring,summer,autumn and winter in the northeast of Chenghua District,Chengdu City.The improved Fernández sequential extraction method for the extracting and separating element speciation of two kinds particulate matter?By optimizing the extractor concentration and volume,extraction time and temperature of the original method at extremely low actual weight?,the HG-AFS and ICP-OES methods were used to determine the arsenic,antimony,potassium,sodium,magnesium,magnesium,iron and aluminum in the extracts of each step.And the seasonal distribution characteristics,migration and transformation rules and bioavailability of these elements in the atmospheric environment of the basin were compared and studied,their enrichment characteristics,factor analysis source analysis and risk assessment were completed,and then backward trajectory model was used to analyze pollutant migration characteristics.These research results have high theoretical and practical reference value for the prevention and control of atmospheric environment pollution and the victory of the"defense of the blue sky".The main work and results are as follows:?1?The improvement and optimization of Fernandez method was completed,and the best optimal extraction conditions are as follows:the experimental water is commercially available pure water,Espom;The extraction liquid volume in each step is 5m L,which is reduced by 50%-66.7%compared with the original method;The optimum concentration of the extractant NH₂OH.HCl in carbonates,oxides and reducible?F2?is 0.20 mol/L,which reduced by 20%;The concentration of NH₄AC in bound to organic matter,oxidisable and sulphidic?F3?is 1.5 mol/L which was 40%lower than that used in Fernandez method;The volume of hydrogen peroxide used in F3 digestion is reduced by 5m L,33.3%reagent is saved;The temperature of soluble and exchangeable?F1?and F2 are 35?,which is close to human body temperature,and the extraction time is reduced by 33.3%and 20.0%.?2?The optimized and improved Fernandez method was used to analyze the speciation and distribution of arsenic,antimony and other elements in PM₁₀ and PM_2.5,and the precision,accuracy and detection limit of the method were evaluated.The relative standard deviations of total arsenic and various forms of arsenic in PM₁₀ and PM_2.5 are 0.220%-6.42%and 0.65%-9.05%,respectively,and antimony were0.306%-9.29%and 0.19%-6.22%,respectively.The detection limits of total arsenic and various forms of arsenic are 0.0017-0.13 ng/m L,and antimony is 0.0017-0.030ng/m L,and the detection data measured by the computer is more than 3 times of the detection limit.The total contents of the measured national standard substance are consistent with the recommended value,and the recoveries rate?the ratio between the sum of all forms and the total amount?is within 96.1%?101.4%.The recovery ranges of arsenic and antimony in PM_2.5 are 90.9%-113%and 86.7%-95.8%,respectively,and that of arsenic and antimony in PM₁₀ are 89.2%-106%and 85.7%-96.7%,respectively.?3?The measured mass concentration of PM₁₀ ranged from 53-209?g/m³,both exceeding the national air quality level I standard,and exceeding the national air quality level II standard in 4 days?exceeding rate 14.3%?,including 2 days in winter and 2 days in spring.The mass concentration of 28 atmospheric particulate matter PM_2.5 samples in the four seasons ranged from 36 to 170?g/m3,all of which exceeded the national air quality first-class standards,including 11 days?6 days in winter,4 days in spring,1 day in autumn?exceeds the national air quality secondary standard?exceeding standard rate 39.3%?,indicating that the two atmospheric particulates in the study area were seriously polluted in winter and spring,especially fine particles?4?The determination of various forms of arsenic,antimony and other elements were completed,and the seasonal distribution characteristics of various forms of arsenic and antimony and the correlation between the forms of arsenic and antimony were analyzed.The total amount of arsenic and antimony in PM₁₀ and PM_2.5 in the northeast of chenghua district of chengdu varies with the season:winter>spring>summer>autumn.The concentration of arsenic and antimony is mainly concentrated in PM_2.5 fine particles,The annual average arsenic concentration in PM₁₀and PM_2.5 is 12.4 ng/m3 and 10.6 ng/m3,which exceeds the national annual reference concentration limit?6 ng/m³?and is slightly higher than the average arsenic concentration in Chinese cities,which should cause the attention of concerned department.The morphological changes of each element are relatively complex,in winter and spring,and are zigzag.The morphology of arsenic and antimony in summer and autumn is more complex than that of lithophile elements,and the source of arsenic and antimony is complex.In the correlation study,it is found that there is a strong correlation between the total arsenic-antimony concentration and the concentration of F1 and F2,and there is also a strong correlation between F1 and F2.Therefore,the higher the total arsenic-antimony concentration is,the greater the harm,and the harmfulness between arsenic-antimony also influences each other.?5?The study of factor analysis and enrichment factor source analysis are completed.The load coefficients of Iron magnesium aluminum on factor 1 are 0.894,0.757 and 0.917,respectively.Iron is the marker element of architectural dust and aluminum is the marker element in the crust,indicating that factor 1 may be soil dust and architectural dust.The enrichment factors of iron and aluminum elements were all less than 10,while the magnesium element was slightly more than 10,which further indicated that factor 1 represented the natural source,that is,mainly from soil dust,and the cumulative genesis rate was up to 44.8%.In factor 2,the load coefficients of arsenic and antimony are 0.879 and 0.818,respectively.Antimony is the identification component of coal burning,and arsenic mainly comes from coal combustion,indicating that factor 2 is coal combustion,and the load enrichment factors of arsenic and antimony were all greater than 10,showing that its source is mainly influenced by human,and the cumulative genesis rate reaches 83.7%.?6?The HYSPLIT backward trajectory was completed to simulate the air mass trajectory in winter,spring,summer and autumn.The results show that the air mass trajectory is short in winter and summer air mass trajectory are short,especially in the winter air mass moving slowly,local pollution sources in chengdu is blocked by the Qinling area,the pollution is not easy to spread,and the air mass affecte by the northeast,southwest and northwest wind,spring affectes by mobile sources over a long distance from Gansu area,It is an important reason for serious metal pollution such as arsenic and antimony in winter and spring in the northeast of chenghua Chengdu.The long track of air mass in summer and autumn indicates the fast moving rate of pollution sources.The northwest and southwest winds move the pollution sources from Xizang and Xinjiang to the sampling area.?7?The bioavailability study of arsenic and antimony was completed,and the results showed that arsenic is a bioavailable element,antimony is a potential bioavailable element.Antimony has a lower non-carcinogenic risk factor in the PM_2.5and PM₁₀.The carcinogenic risk values of arsenicin the PM_2.5and PM₁₀ were:6.69×10^-7,7.77×10^-7 for children;For adults,it is 1.35×10^-6,1.57×10^-6,indicating that arsenic has a strong carcinogenic risk for adults,which should be taken seriously.