气候变化领域集成服务门户(CCPortal): Long-term total OH reactivity measurements in a boreal forest

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DOI	10.5194/acp-19-14431-2019
	Long-term total OH reactivity measurements in a boreal forest
	Praplan A.P.; Tykkä T.; Chen D.; Boy M.; Taipale D.; Vakkari V.; Zhou P.; Petäjä T.; Hellén H.
发表日期	2019
ISSN	16807316
起始页码	14431
结束页码	14453
卷号	19 期号:23
英文摘要	Total hydroxyl radical (OH) reactivity measurements were conducted at the second Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II), a boreal forest site located in Hyytiälä, Finland, from April to July 2016. The measured values were compared with OH reactivity calculated from a combination of data from the routine trace gas measurements (station mast) as well as online and offline analysis with a gas chromatographer coupled to a mass spectrometer (GC-MS) and offline liquid chromatography. Up to 104 compounds, mostly volatile organic compounds (VOCs) and oxidized VOCs, but also inorganic compounds, were included in the analysis, even though the data availability for each compound varied with time. The monthly averaged experimental total OH reactivity was found to be higher in April and May (ca. 20s-1) than in June and July (7.6 and 15.4s-1, respectively). The measured values varied much more in spring with high reactivity peaks in late afternoon, with values higher than in the summer, in particular when the soil was thawing. Total OH reactivity values generally followed the pattern of mixing ratios due to change of the boundary layer height. The missing reactivity fraction (defined as the difference between measured and calculated OH reactivity) was found to be high. Several reasons that can explain the missing reactivity are discussed in detail such as (1) missing measurements due to technical issues, (2) not measuring oxidation compounds of detected biogenic VOCs, and (3) missing important reactive compounds or classes of compounds with the available measurements. In order to test the second hypothesis, a one-dimensional chemical transport model (SOSAA) has been used to estimate the amount of unmeasured oxidation products and their expected contribution to the reactivity for three different short periods in April, May, and July. However, only a small fraction (<4.5%) of the missing reactivity can be explained by modelled secondary compounds (mostly oxidized VOCs). These findings indicate that compounds measured but not included in the model as well as unmeasured primary emissions contribute the missing reactivity. In the future, non-hydrocarbon compounds from sources other than vegetation (e.g. soil) should be included in OH reactivity studies. © 2019 BMJ Publishing Group. All rights reserved.
语种	英语
scopus关键词	atmospheric chemistry; atmospheric transport; boreal forest; concentration (composition); hydroxyl radical; source apportionment; volatile organic compound; Finland
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/144009
作者单位	Atmospheric Composition Research, Finnish Meteorological Institute, P. O. Box 503, Helsinki, 00101, Finland; Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P. O. Box 64, Helsinki, 00014, Finland; Unit for Environmental Sciences and Management, North-West University, Potchefstroom, 2520, South Africa
推荐引用方式 GB/T 7714	Praplan A.P.,Tykkä T.,Chen D.,et al. Long-term total OH reactivity measurements in a boreal forest[J],2019,19(23).
APA	Praplan A.P..,Tykkä T..,Chen D..,Boy M..,Taipale D..,...&Hellén H..(2019).Long-term total OH reactivity measurements in a boreal forest.Atmospheric Chemistry and Physics,19(23).
MLA	Praplan A.P.,et al."Long-term total OH reactivity measurements in a boreal forest".Atmospheric Chemistry and Physics 19.23(2019).