發(fā)布時(shí)間：2017-12-28 22:08

  本文關(guān)鍵詞：我國大氣二次有機(jī)氣溶膠分布與來源的初步研究　出處：《中國科學(xué)院研究生院(廣州地球化學(xué)研究所)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 二次有機(jī)氣溶膠 異戊二烯 苯系物 中國 青藏高原 空間分布 季節(jié)變化 源解析

【摘要】：二次有機(jī)氣溶膠(SOA)源于反應(yīng)性有機(jī)氣體的大氣氧化產(chǎn)物,在已有氣溶膠顆粒上的凝聚以及有機(jī)氣溶膠的大氣演化。SOA是大氣細(xì)粒子的重要組成部分,對全球氣候變化、區(qū)域空氣質(zhì)量和人群健康有重要影響。當(dāng)前在SOA來源與形成機(jī)制方面仍有諸多問題尚不清楚,基于現(xiàn)有認(rèn)識進(jìn)行的模式計(jì)算結(jié)果與實(shí)際觀測之間,仍有1-2個(gè)數(shù)量級的差別。另一方面,我國目前面臨著嚴(yán)峻的細(xì)粒子污染問題,而SOA在其中扮演著重要角色,是區(qū)域細(xì)粒子污染控制的難點(diǎn)。明確SOA分布、組成與來源,對于準(zhǔn)確把握其氣候環(huán)境效應(yīng)有重要意義。本論文在全國開展SOA觀測,通過有機(jī)示蹤物,以點(diǎn)-面結(jié)合的方式,初步分析了我國SOA的時(shí)空分布與組成來源。相關(guān)結(jié)果如下:2012年夏季在中國的6個(gè)區(qū)域14個(gè)城市同時(shí)用石英膜采集顆粒物樣品,分析生物源前體物(異戊二烯、單萜烯、β-石竹烯)和人為源前體物(苯系物)生成的SOA示蹤物。所測13種SOA示蹤物的總濃度范圍是29.9-371 ng m-3,異戊二烯的示蹤物濃度最高(123±78.8 ng m-3),其次是單萜烯(10.5±6.64 ng m-3)、β-石竹烯(5.07±3.99 ng m-3)、苯系物示蹤物(2.90±1.52 ng m-3)。生物源示蹤物的最高濃度出現(xiàn)在中國東部,苯系物示蹤物的最高濃度出現(xiàn)在中國的北方。生物源示蹤物的濃度均與溫度呈現(xiàn)正相關(guān)關(guān)系,表明生物源前體物的排放是影響夏季全國范圍內(nèi)生物源SOA空間分布的主要因素。在異戊二烯的示蹤物中,低NOx產(chǎn)物2-methyltetrols占主要地位,但是,在某些城市地區(qū),高NOx產(chǎn)物2-methylglyceric acid的貢獻(xiàn)升高,表明在城市地區(qū)人為源排放對異戊二烯SOA生成有較大影響。對于單萜烯SOA示蹤物,其第一代產(chǎn)物(pinonic acid和pinic acid)與后繼產(chǎn)物(3-methyl-1,2,3-butanetricarboxylic acid)的比值(P/M)與后繼產(chǎn)物濃度之間呈現(xiàn)顯著負(fù)相關(guān),表明P/M比值可以用來表征單萜烯SOA的老化程度。各站點(diǎn)的P/M比值在0.89-21.0之間,表明夏季單萜烯SOA老化程度相對低。作為典型的人為源SOA示蹤物,2,3-dihydroxy-4-oxopentanoic acid(DHOPA)在城鎮(zhèn)地區(qū)濃度遠(yuǎn)高于偏遠(yuǎn)地區(qū)。進(jìn)一步應(yīng)用SOA示蹤物法估算了我國夏季二次有機(jī)碳(SOC)和SOA的總量與來源。SOC和SOA的濃度范圍分別為0.37-2.47μg C m-3和0.81-5.44μg m-3,且高濃度出現(xiàn)在我國東部地區(qū)。異戊二烯和苯系物是我國夏季SOA的主要來源,分別貢獻(xiàn)46±14%和27±8%。在華北地區(qū),苯系物是最主要來源。這些結(jié)果表明,以苯系物為代表的人為源前體物是我國大氣SOA的重要來源。在青藏高原的納木錯(cuò)站,從2012年7月至2013年7月,開展了為期一年的采樣觀測,分析了顆粒物樣品中生物源前體物(異戊二烯、單萜烯、β-石竹烯)和人為源前體物(苯系物)生成的SOA示蹤物。在所測化合物中,異戊二烯SOA示蹤物占據(jù)主導(dǎo)地位(26.6-44.2 ng m-3)其次是單萜烯(0.97-0.57 ng m-3)、苯系物(DHOPA,0.25-0.18 ng m-3)以及β-石竹烯(0.09-0.10 ng m-3)。異戊二烯示蹤物的濃度夏天最高,冬天最低,其變化受溫度顯著影響,且與異戊二烯排放受溫度影響一致,表明納木錯(cuò)地區(qū)的異戊二烯SOA示蹤物濃度季節(jié)變化受控于異戊二烯排放。由于受溫度和相對濕度影響方面的差異,異戊二烯的高NOx和低NOx產(chǎn)物的濃度比值在冬天最高,夏天最低。單萜烯SOA示蹤物的濃度變化,受單萜烯排放和示蹤物氣-粒分配的雙重影響,因而在夏季其濃度沒有明顯的升高。苯系物SOA示蹤物DHOPA首次在全球本底區(qū)觀測到,其濃度比全球城市地區(qū)低1-2個(gè)數(shù)量級。DHOPA高值出現(xiàn)在夏季,氣團(tuán)軌跡反演顯示,其主要來自印度東部和孟加拉;在冬季,納木錯(cuò)地區(qū)的氣團(tuán)主要來自印度東北部,DHOPA的濃度雖然降低,但其在示蹤物總量中所占比重反而升高。應(yīng)用SOA示蹤物法估算的結(jié)果顯示,納木錯(cuò)地區(qū)SOC的年均濃度為0.22±0.29μg C m-3,生物源的貢獻(xiàn)約占75%。夏季,異戊二烯對SOC貢獻(xiàn)超過80%;冬季,極低的溫度導(dǎo)致生物源前體物的排放大大減少,苯系物的貢獻(xiàn)顯著提高。這些結(jié)果表明,來自印度半島的人為源污染物可以被運(yùn)輸?shù)角嗖馗咴�地區(qū),并影響該地區(qū)的SOC組成。
[Abstract]:The two organic aerosol (SOA) originates from the atmospheric oxidation products of reactive organic gases, the condensation on the existing aerosol particles and the atmospheric evolution of organic aerosols. SOA is an important component of fine particles in the atmosphere. It has an important impact on global climate change, regional air quality and population health. At present, there are still many problems in the origin and formation mechanism of SOA. It is not clear that there are 1-2 orders of magnitude difference between the calculated results based on the existing knowledge and the actual observations. On the other hand, China is facing a serious problem of fine particle pollution, and SOA plays an important role in it. It is the difficulty of controlling the fine particle pollution in the region. The clear distribution, composition and source of SOA is of great significance to accurately grasp the effect of climate and environment. In this paper, SOA observation was carried out throughout the country, and the spatial and temporal distribution and source of SOA in China were preliminarily analyzed through the combination of organic tracers and point to surface. The related results are as follows: in the summer of 2012, 6 regions and 14 cities in China were collected, and quartz particles were used to collect particulate matter samples. The SOA tracers of biological precursors (isoprene, monoterpene, beta carthene) and human precursors (benzene series) were analyzed. The total concentration range of the 13 SOA tracers was 29.9-371 ng M-3, the highest concentration of isoprene tracers was (123 + 78.8 ng M-3), followed by monoterpene (10.5 + 6.64 ng M-3), beta carnation (5.07 + 3.99 ng M-3), and benzene series tracers (2.90 + 1.52 ng ng). The highest concentration of biogenic tracers occurs in eastern China, and the highest concentration of the tracer is in the north of China. The concentration of biological source tracers is positively correlated with temperature, indicating that the emission of biological precursors is the main factor affecting the spatial distribution of biological SOA in summer. In the isoprene tracers, the low NOx product 2-methyltetrols plays a dominant role. However, in some urban areas, the contribution of high NOx product 2-methylglyceric acid increases, indicating that the emission of anthropogenic sources has great influence on the SOA generation of isoprene in the urban area. The monoterpene SOA tracer, the first generation of products (Pinonic acid and pinic acid) and subsequent product (3-methyl-1,2,3-butanetricarboxylic acid) ratio (P/M) and subsequent product concentration showed a significant negative correlation, shows that the aging degree of the P/M ratio can be used to characterize the monoterpene SOA. The P/M ratio at each site was between 0.89-21.0, indicating that the aging degree of monoterpene SOA was relatively low in summer. As a typical anthropogenic SOA tracer, the concentration of 2,3-dihydroxy-4-oxopentanoic acid (DHOPA) in urban areas is far higher than that in remote areas. The total amount and source of two organic carbon (SOC) and SOA in the summer of China were estimated by the SOA tracer method. The concentration range of SOC and SOA is 0.37-2.47 g C M-3 and 0.81-5.44 u g M-3 respectively, and the high concentration appears in the eastern part of China. Isoprene and benzenes are the main sources of SOA in summer in China, contributing 46 + 14% and 27 + 8% respectively. In North China, the benzene series is the most important source. These results indicate that the precursor precursors, represented by the benzene series, are an important source of SOA in the atmosphere in China. In the Nam Co station on Qinghai Tibet Plateau, from July 2012 to July 2013, a year of sampling observation was carried out, and the SOA tracers of biological precursors (isoprene, monoterpene, beta carthene) and human precursor precursors (benzene series) were analyzed. Among the compounds tested, isoprene SOA tracers are dominant (26.6-44.2 ng M-3), followed by monoterpene (0.97-0.57 ng M-3), benzene series (DHOPA, 0.25-0.18 ng M-3), and beta carnation (0.25-0.18). The concentration of isoprene tracer is the highest in summer and lowest in winter. Its change is significantly affected by temperature and is consistent with the temperature of isoprene discharge. It indicates that the seasonal variation of isoprene SOA tracer concentration in Nam Co area is controlled by isoprene emission. Due to the difference in temperature and relative humidity, the concentration ratio of high NOx and low NOx products of isoprene is highest in winter and lowest in summer. The concentration change of monoterpene SOA tracer is influenced by the dual effects of monoterpene emission and tracer gas particle distribution, so the concentration of monoterpene is not significantly increased in summer. The SOA tracer DHOPA of the benzene series was first observed in the global base area, and its concentration was 1-2 orders of magnitude lower than that of the global urban area. DHOPA high value appeared in summer. Air mass trajectory inversion showed that it mainly came from Eastern India and Bangladesh. In winter, the air masses in Nam Co area mainly came from northeastern India, while the concentration of DHOPA decreased, but its proportion in tracers increased. The results of SOA tracer method showed that the annual average concentration of SOC in Nam Co area was 0.22 + 0.29 mu g C M-3, and the contribution of biological sources was about 75%. In summer, the contribution of isoprene to SOC was more than 80%; in winter, the very low temperature caused the emission of precursors to be greatly reduced and the contribution of benzene compounds increased significantly. These results indicate that the anthropogenic pollutants from the India peninsula can be transported to the Qinghai Tibet Plateau and affect the SOC composition of the region.
【學(xué)位授予單位】：中國科學(xué)院研究生院(廣州地球化學(xué)研究所)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X513

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