大气气溶胶的WIBS预测及转化和来源研究

发布时间：2018-04-28 04:25

本文选题：生物气溶胶 + 燃烧影响　；参考：《中国科学技术大学》2017年博士论文

【摘要】：不同地区气溶胶的成分差别很大,城市作为人口密度集中的聚居地,健康问题是我们不可忽视的部分。生物源的气溶胶是大气气溶胶的重要组成部分,对全球的气候变化和环境健康起着重要的作用。一方面可以通过反射太阳辐射改变大气层的温度以及作为云凝结核和冰核从而直接或间接的影响气候变化。另一方面存在于空气中的病毒、细菌、真菌等会传播动植物疾病,威胁人类健康。随着城市的发展,雾霾事件频繁出现,现代城市人感染哮喘和过敏的几率也越来越大。传统的生物气溶胶的检测手段通常耗时较长,且不能精确的统计其在大气中的浓度,因此需要有高效的方法对城市生物气溶胶进行检测。近年来荧光检测技术得到了快速的发展,出现了在线检测生物气溶胶的仪器,但是目前在国内的应用范围还很小。生物源挥发性有机物(BVOC)是生物源的二次有机气溶胶(SOA)的前体物质,占全球挥发性有机物(VOC)排放的主要部分。海洋作为地表覆盖率最高的区域,对全球气候变化起着重要的调节作用,远洋大气亦可以作为研究城市大气环境的背景地区,研究海洋上空BVOC可以更好的了解远洋SOA的生成。对远洋气溶胶稳定碳氮同位素的研究可以帮助探讨远洋气溶胶的来源和传输过程。本研究依据两次国内的野外监测和第29次以及第30次南极科学考察,第一次使用荧光在线气溶胶仪器对国内污染城市进行了生物气溶胶的检测并探讨了海洋排放的BVOC及其对海洋SOA的贡献以及远洋地区稳定碳氮同位素的分布。得到主要内容和结论如下:(1)城市地区的荧光气溶胶的浓度高于背景地区1-2个数量级。南京和厦门地区宽频综合生物气溶胶光谱仪(WIBS)在线检测的荧光气溶胶的浓度分别为 FL1:0.57 cm-3,FL2:3.35 cm-3,FL3:2.09 cm-3 和 FL1:0.24 cm-3,FL2:0.78 cm-3,FL3:0.40 cm-3。南京地区的荧光气溶胶出现明显的日夜变化特征,而厦门地区昼夜变化不明显。荧光气溶胶的浓度都随着粒径的增加而逐渐降低。粒径在1-2 μm的颗粒物占荧光气溶胶的主导地位,所有粒径在3.8 μm以上的颗粒物都有FL2荧光信号。南京地区的荧光气溶胶的AF(Asymmetry Factor)呈现单峰分布的模式,峰值为～24,而厦门地区的呈现双峰分布的模式,峰值为～23和～30,说明南京地区荧光颗粒物的形状分布比较单一。(2)荧光气溶胶的浓度在一定程度上受当地气象参数的影响,一定的风速会增加植物花粉和孢子的排放,导致生物气溶胶的浓度上升。但当风速超过一定阈值时,会加快大气颗粒物的扩散速度,导致当地生物气溶胶的浓度降低。降雨之前生物气溶胶的浓度会上升,温度和湿度也可以影响生物气溶胶的释放。(3)南京地区的生物气溶胶显著的高于一些森林等生物气溶胶含量丰富的背景地区,尤其是FL1荧光通道与MBC/PM0.8示了很好的正相关性(r=0.75),因此直接用WIBS仪器的三个荧光通道来代表生物气溶胶并不合适。根据荧光强度和占总颗粒物的比例与MBC/PM0.8的相关性,将荧光气溶胶分成了燃烧排放相关的和非燃烧相关的颗粒物两类。燃烧排放相关的荧光颗粒物和非燃烧排放相关的荧光颗粒物分别占总颗粒物的～11%和～5%。非燃烧相关的颗粒物浓度为0.64 cm-3仍然高于其他文献报道的南京地区生物气溶胶的浓度,因此并不能确定非燃烧相关的荧光颗粒物就是生物气溶胶,可能包含了灰尘等其他的颗粒物。(4)第29次南极科学考察航线上的异戊二烯和α蒎烯、β蒎烯的浓度分别为113 pptv、28 pptv和14 pptv。异戊二烯的浓度显著高于单萜,三者之间有很好的相关性。整个航线上异戊二烯和单萜的地理分布没有显著性差异,普里兹湾表现出很高的异戊二烯和单萜浓度,和普利滋区域蓝藻爆发有一定的关系。不同浮游植物的种类、风速和温度都会影响海洋大气异戊二烯和蒎烯的浓度分布。普里兹湾异戊二烯生成的SOA占全球海洋排放异戊二烯生成SOA的0.03%。(5)第30次南极航线上气溶胶总悬浮颗粒物中总碳的质量浓度(TC)平均值为1±0.81 μgm-3 TC的浓度随着纬度的升高逐渐降低(r=0.58,p0.01)低纬度的TC受到陆地的影响较大。整个航线上有29%的样品未检出总氮(TN),TN的平均浓度为0.49±0.74 μg m-3,整体浓度偏低,且远远低于大城市中的浓度。TN的浓度也随着纬度的升高而降低(r=0.37,p0.01)。稳定碳同位素δ13C的平均值为-27±3.3‰,且513C与TC有一定的相关性(r=0.34,p0.05)。稳定氮同位素515N的平均值为0.9±3.3‰,与TN没有相关性。δ13C和δ15N的分布与纬度都没有相关性。低纬度的样品受到亚洲大陆和菲律宾群岛,澳洲大陆两部分气团的影响,受亚洲大陆和菲律宾群岛气团影响的样品中的碳氮可能来源于陆地的生物质燃烧。中纬度地区样品可能受到南极大陆尘埃的影响。高纬度地区的碳氮与海洋浮游植物的排放有一定的关系。
[Abstract]:The composition of aerosol is very different in different regions. As a place where population density is concentrated, the health problem is the part that we can not ignore. The aerosol of the biogenic source is an important part of the atmospheric aerosol. It plays an important role in the global climate change and environmental health. The temperature of the atmosphere, as well as as a cloud of nodules and ice nuclei, directly or indirectly affects climate change. On the other hand, the virus, bacteria and fungi in the air can spread animal and plant diseases and threaten human health. With the development of the city, the haze events frequently occur, and the risk of asthma and allergy in modern urban people is also increasing. The traditional detection methods of biological aerosol are usually time-consuming and can not accurately count their concentration in the atmosphere. Therefore, it is necessary to have a high efficient method for the detection of urban bioaerosols. In recent years, the fluorescence detection technology has been developed rapidly, and the instrument for on-line detection of biological aerosol has appeared, but it should be in the country at present. The biological volatile organic compounds (BVOC) are the precursors of the two organic aerosol (SOA) of the biogenic source, which account for the major part of the global emissions of volatile organic compounds (VOC). As the region with the highest surface coverage, the ocean plays an important role in the global climate change, and the ocean atmosphere can also be used as a research city. The study of BVOC over the ocean can better understand the formation of ocean SOA in the background of the air environment. The study of the stable carbon and nitrogen isotopes of the sols can help to explore the source and transmission process of oceanic aerosols. This study was based on two domestic field monitoring and twenty-ninth and thirtieth Antarctic scientific expedition, for the first time. The BVOC and its contribution to marine SOA and the distribution of stable carbon and nitrogen isotopes in ocean areas are discussed. The main contents and conclusions are as follows: (1) the concentration of fluorescent gas solution in urban areas is 1-2 orders of magnitude higher than that in the background area. The concentration of fluorescent aerosol detected on line by WIBS in Beijing and Xiamen region was FL1:0.57 cm-3, FL2:3.35 cm-3, FL3:2.09 cm-3 and FL1:0.24 cm-3, FL2:0.78 cm-3. The fluorescent aerosols in Nanjing region showed obvious diurnal change characteristics, while the day and night changes in Xiamen were not obvious. The concentration of the fluorescent aerosol gradually decreases with the increase of the particle size. The particles with a particle size of 1-2 mu m occupy the dominant position of the fluorescent aerosol, and all the particles with a particle size of more than 3.8 m have FL2 fluorescence signals. The AF (Asymmetry Factor) of the fluorescent aerosol in Nanjing region shows a single peak distribution pattern, the peak value is 24, and the Xiamen region has a peak value. The pattern of Shuangfeng distribution is 23 and 30, which indicates that the shape distribution of the fluorescent particles in Nanjing is relatively simple. (2) the concentration of the fluorescent aerosol is influenced by the local meteorological parameters to a certain extent. A certain wind speed will increase the emission of pollen and spores of plants and lead to the increase of the concentration of the biological aerosol. When a certain threshold is passed, the diffusion rate of atmospheric particles will be accelerated and the concentration of the local biological aerosol is reduced. The concentration of biological aerosols will rise before rainfall, and the temperature and humidity can also affect the release of biological aerosols. (3) the biological aerosols in the Nanjing region are significantly higher than those of some forests and other bioaerosols. The region, especially the FL1 fluorescent channel, shows good positive correlation with MBC/PM0.8 (r=0.75), so it is not appropriate to represent the biological aerosols directly with the three fluorescent channels of the WIBS instrument. According to the correlation of the fluorescence intensity and the proportion of the total particles to the MBC/PM0.8, the fluorescence aerosol is divided into the combustion emission related and non combustion phase. Two kinds of particulate matter. The emission related emission related fluorescent particles and non combustion emission related fluorescent particles accounted for 11% of the total particles and the concentration of non combustion related particles of 0.64 cm-3 were higher than those of other literature reported in Nanjing. Therefore, the non combustion related fluorescence was not determined. Particles are bioaerosols, which may contain other particles such as dust. (4) the concentration of isoprene and alpha pinene on the twenty-ninth Antarctic scientific voyage routes, the concentration of beta pinene is 113 pptv, 28 pptv and 14 pptv. isoprene are significantly higher than monoterpene, and the three are well correlated. There is no significant difference in the geographical distribution of terpenes. Prisi Bay shows a high concentration of isoprene and monoterpene, which has a certain relationship with the explosion of cyanobacteria in the prisi region. The species of phytoplankton, wind speed and temperature will affect the concentration distribution of isoprene and pinene in the ocean atmosphere. The SOA of the isoprene in prise Bay accounts for the global sea. The mass concentration of total carbon in aerosol total suspended particulate matter (TC) on 0.03%. (5) on the thirtieth Antarctic route of isoprene generated SOA was 1 + 0.81 mu GM-3 TC as the latitude increased gradually (r=0.58, P0.01), and the low latitude TC was greatly affected by land. 29% samples were not detected total nitrogen (TN), TN on the whole route. The average concentration is 0.49 + 0.74 g M-3, the whole concentration is low, and the concentration of.TN is also lower than that in the large cities (r=0.37, P0.01). The average value of the stable carbon isotope Delta 13C is -27 + 3.3 per thousand, and 513C and TC have some correlation (r=0.34, P0.05). The average value of the stable nitrogen isotope 515N is 0.9 + 3.3 per thousand. There is no correlation with TN. The distribution of delta 13C and delta 15N has no correlation with latitude. The low latitude samples are affected by the Asian continent and Philippines islands, the two parts of the Australian continent, and the carbon and nitrogen in the samples affected by the Asian continent and the Philippines archipelago may be derived from the biomass burning on the land. The influence of the dust on Antarctica is related to the carbon and nitrogen in high latitudes and the discharge of marine phytoplankton.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X513

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