發(fā)布時間：2018-06-27 04:43

  本文選題：有機(jī)酸 + 大氣顆粒物��； 參考：《西北大學(xué)》2017年碩士論文

【摘要】：有機(jī)酸是大氣顆粒物中重要的有機(jī)組分,其強(qiáng)吸濕性可以改變顆粒物的粒徑分布與云凝結(jié)核狀態(tài)進(jìn)而影響全球氣候、大氣能見度及人體健康。二元羧酸(DCAs)是大氣中揮發(fā)性有機(jī)物的氧化降解產(chǎn)物,也是二次有機(jī)氣溶膠(SOA)的重要組分,復(fù)雜的形成過程導(dǎo)致其在不同大氣環(huán)境中的濃度分布存在明顯的差異。當(dāng)前關(guān)于SOA來源與形成機(jī)制方面的難題尚未解決,基于煙霧箱模擬、模型計算與實際監(jiān)測結(jié)果之間的較大差異,明確大氣環(huán)境中SOA類二元羧酸的實際組成及分布,對于準(zhǔn)確解析霧霾成因具有重要意義。本論文開展了西安市大氣顆粒物中有機(jī)酸的分析,主要內(nèi)容如下:(1)綜述部分對大氣顆粒物中有機(jī)酸的環(huán)境效應(yīng)、濃度分布特征、測定方法、形成機(jī)制及來源解析做了詳盡的闡述,并結(jié)合近期大氣環(huán)境領(lǐng)域SOA類有機(jī)酸的研究動態(tài)及前沿性問題提出了本論文的研究意義及主要內(nèi)容。(2)大氣顆粒物中二元羧酸的污染特征。以西安市大氣顆粒物為研究對象,于2015年7月13-24日,2016年1月8-28日在三個采樣點(diǎn)(城區(qū)、郊區(qū)、鄉(xiāng)村)采集PM2.5和PM10樣品,并用吸收液同步采集了氣相中的有機(jī)酸。使用極性溶劑提取樣品中的DCAs并將其衍生,建立了 15種二元羧酸丁酯的氣相色譜定量分析方法,考察了方法的精密度(3.6-7.3%)、加標(biāo)回收率(68.2%～119.6%)、最低檢出限(36.4-82.5 μg/L),確定該方法可用于顆粒物樣品中DCAs的定量分析。主要研究了不同區(qū)域、不同季節(jié)、不同粒徑、不同天氣條件下顆粒物中DCAs的濃度分布,結(jié)果表明城區(qū)DCAs含量冬季高于夏季、霧霾天(2363 ng/m3)高于晴朗天(921 ng/m3)。DCAs總濃度城區(qū)郊區(qū)鄉(xiāng)村,且DCAs易分配到細(xì)顆粒物中,其氣粒分配比與濕度、臭氧濃度呈負(fù)相關(guān)。(3)大氣顆粒物中一元羧酸(MCAs)的污染特征。用極性較弱的溶劑提取樣品中的MCAs,并將其甲酯化,應(yīng)用氣相色譜方法定量分析32種一元羧酸甲酯,方法的RSD值(小于12%)、回收率(69.2%～117.6%)、檢出限(23.6-55.8 μg/L)均能滿足樣品中的MCAs的定量分析。同時研究了顆粒物中MCAs分子的季節(jié)、粒徑以及在污染事件中的濃度分布特征,結(jié)果表明C16的含量最高,其濃度分布與一次排放量直接相關(guān)。城區(qū)冬季(1193ng/m3)MCAs的含量高于夏季(541ng/m3),霧霾天高于晴朗天。在PM10中的濃度高于PM2.5、較高的氣粒分配比是MCAs與DCAs的明顯差異。(4)PM2.5中有機(jī)酸的來源分析采用DCAs、MCAs化合物間的比值特征分析方法,結(jié)合DCAs與前體物、大氣氧化性、有機(jī)污染物的相關(guān)性研究,并將MCAs與有機(jī)污染物、臭氧濃度進(jìn)行相關(guān)性分析。結(jié)果表明DCAs濃度與前體物濃度、大氣氧化劑濃度呈正相關(guān),MCAs濃度與正構(gòu)烷烴、稠環(huán)芳烴呈正相關(guān)。得到西安市顆粒物中的MCAs主要來源于一次排放、DCAs主要來源于光化學(xué)反應(yīng)的結(jié)論。光化學(xué)反應(yīng)易受光化學(xué)氧化劑濃度、光照強(qiáng)度等條件的影響,光照強(qiáng)度、臭氧濃度越高光化學(xué)反應(yīng)越劇烈,生成的DCAs越多。酮酸化合物的液相氧化也是DCAs的重要生成途徑,且環(huán)境相對濕度是制約氧化反應(yīng)強(qiáng)弱的關(guān)鍵因素。
[Abstract]:Organic acids are important organic components in atmospheric particles. Their strong hygroscopicity can change the particle size distribution of particles and the state of cloud coagulating tuberculosis and then affect the global climate, atmospheric visibility and human health. The two meta carboxylic acid (DCAs) is the oxidation and degradation product of the volatile organic compounds in the atmosphere, and is also an important component of the two organic aerosol (SOA). The complex formation process leads to the obvious difference in the concentration distribution in different atmospheric environment. The current problems about the source and formation mechanism of SOA have not been solved. Based on the smoke box simulation, the large difference between the model calculation and the actual monitoring results is made, and the actual composition and distribution of the type SOA two meta carboxylic acid in the atmospheric environment are clearly defined. The analysis of organic acids in atmospheric particulates in Xi'an is carried out in this paper. The main contents are as follows: (1) the overview of the environmental effects, concentration distribution characteristics, determination methods, formation mechanism and source analysis of atmospheric particles in atmospheric particulates is described in detail, and the recent atmospheric environment is combined with the atmospheric environment. The research significance and main content of this paper are put forward in the field of research on SOA organic acids in the field. (2) the pollution characteristics of two meta carboxylic acids in atmospheric particles. Taking the atmospheric particulates in Xi'an as the research object, PM2.5 and PM10 samples were collected at three sampling points (urban, suburban and rural) on 13-24 day of July 2015 and 8-28 on January 2016. The organic acids in the gas phase are collected synchronously with the absorption solution. Using the polar solvent to extract the DCAs in the sample and derive it, 15 kinds of gas chromatography quantitative analysis methods for two meta carboxylic butyl ester are established. The precision (3.6-7.3%), the recovery rate (68.2% ~ 119.6%) and the minimum detection limit (36.4-82.5 mu g/L) are investigated. It can be used for quantitative analysis of DCAs in particle samples. The concentration distribution of DCAs in different regions, different seasons, different grain sizes and different weather conditions is mainly studied. The results show that the DCAs content in the urban area is higher in winter than in summer, fog and haze days (2363 ng/m3) is higher than that of clear sky (921 ng/m3).DCAs in urban rural areas, and DCAs is easily distributed. In fine particles, the distribution of gas particles is negatively correlated with the humidity and ozone concentration. (3) the pollution characteristics of the mono carboxylic acid (MCAs) in the atmospheric particles. The MCAs in the sample is extracted with a weak polar solvent, and its methyl ester is methylated. The quantitative analysis of 32 kinds of mono carboxylic acid methyl esters by gas chromatography, the RSD value of the method (less than 12%), and the recovery rate (69.2% ~ 1). 17.6%), the detection limit (23.6-55.8 mu g/L) can satisfy the quantitative analysis of MCAs in the samples. At the same time, the season, particle size and concentration distribution characteristics of MCAs molecules in the particulate matter are studied. The results show that the content of C16 is the highest, and the concentration distribution is directly related to the first emission. The content of the urban winter (1193ng/m3) MCAs is higher than that in the summer. 541ng/m3, the fog and haze is higher than the clear sky. The concentration in PM10 is higher than that of PM2.5, and the higher gas distribution ratio is the obvious difference between MCAs and DCAs. (4) the source analysis of organic acids in PM2.5 uses the analysis method of the ratio characteristic between DCAs, MCAs compound, the correlation of air oxidation and organic pollutants combined with DCAs and precursors, and MCAs. The correlation analysis between the concentration of ozone and organic pollutants shows that the concentration of DCAs is positively correlated with the concentration of precursor and the concentration of atmospheric oxidizer, and the concentration of MCAs is positively related to n-alkanes and polycyclic aromatic hydrocarbons. The main source of MCAs in the particles in Xi'an is the first emission, and the main source of DCAs is the conclusion of photochemical reaction. The effect of the concentration of photochemical oxidant, light intensity and other conditions, the intensity of light and the higher the concentration of ozone, the more intense the photochemical reaction is, the more DCAs is produced. The liquid phase oxidation of ketoacid compounds is also an important way of generating DCAs, and the relative humidity of the environment is the key factor restricting the oxidation reaction strength.
【學(xué)位授予單位】：西北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X513

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