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Impacts of atmospheric degradation mechanisms of biogenic volatile organic compounds on aerosol formation potential and property of cloud condensation nuclei

生物挥发性有机化合物的大气降解机制对气溶胶形成潜力和云凝结核性质的影响

基本信息

批准号：
17310014
负责人：
IMAMURA Takashi
金额：
$ 9.4万
依托单位：
National Institute for Environmental Studies
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

Secondary organic aerosol (SOA) formation from volatile organic compounds (VOCs) was investigated using a photochemical reaction chamber with an inner volume of 6-m^3. Isoprene is the most abundant biogenic hydrocarbon and its dominant sink in the atmosphere is the reaction with OH radicals in the daytime. Due to its large emission rate, it is important to know if isoprene oxidation leads to SOA production and what is a dominant factor to control the SOA formation yield. SOA formation in the NO_x-photooxidation of isoprene was always observed after photochemical ozone was formed. The concentration of isoprene lost before SOA was formed became lower with decreasing the initial Nox concentration, whereas the total aerosol yield increased with increasing NOT. Experimental results could be explained in terms that RO_2-radical reactions with HO_2 radical contribute the formation of condensable species.SOA formation in the isoprene ozonolysis was also observed. The aerosol formation yield wa … More s markedly depressed by adding excess amount of OH-radical scavengers, while the size of depression of aerosol formation was insensitive to the species of scavenger. Aerosol mass spectrum observed in the presence of OH-radical scavenger, CO, was different from that observed in the absence of the scavenger. These results suggest that OH-initiated reactions are essential to the production of SOAandthe direct ozone reaction with isoprene less produces SOA than OH-oxidation reaction.The SOA mass yields from the photooxidation of aromatic hydrocarbons (AHCs), such as toluene, p-ethyltoluene, p-xylene and 1, 3, 5-trimethylbenzene, were also measured: The SOA yield from each AHC depended on the initial ARC concentration. A previously proposed reaction scheme, in which condensable products are assumed to be formed by secondary reactions of primary oxidation products with ozone, was examined for the interpretations of the present experimental results. As for each AHC, the SOA concentrations measured as a function of the concentration of reacted AHC were successfully explained under various conditions by the previously proposed two-step reaction scheme. Less

利用内容积为6 m^3的光化学反应室研究了挥发性有机化合物（VOCs）形成二次有机气溶胶（SOA）的过程。异戊二烯是最丰富的生物源烃，其在大气中的主要汇是在白天与OH自由基的反应。由于其大的排放速率，重要的是要知道异戊二烯氧化是否导致SOA的生产和什么是控制SOA形成产率的主导因素。在异戊二烯的NO_x光氧化反应中，SOA的形成总是在光化学臭氧形成之后。随着NOx初始浓度的降低，SOA形成前的异戊二烯损失浓度逐渐降低，而总气溶胶产额则随着NOx初始浓度的增加而增加。实验结果可以用RO_2-自由基与HO_2自由基反应生成可冷凝物来解释。气溶胶形成产率为 ...更多信息过量的OH-自由基清除剂可显著抑制气溶胶的生成，但抑制气溶胶生成的大小与清除剂的种类无关。在OH-自由基清除剂CO存在下观察到的气溶胶质谱与在不存在清除剂的情况下观察到的气溶胶质谱不同。研究了甲苯、对乙基甲苯、对二甲苯和1，3，5-三甲苯等芳烃的光氧化反应，并测定了不同芳烃光氧化反应的SOA质量产率：不同芳烃光氧化反应的SOA产率与初始ARC浓度有关。一个先前提出的反应方案，其中可冷凝的产品被假定为形成的初级氧化产物与臭氧的二次反应，进行了检查本实验结果的解释。对于每一个AHC，SOA浓度作为反应的AHC的浓度的函数测量成功地解释了在各种条件下由先前提出的两步反应方案。少