Zobrazeno 1 - 10
of 173
pro vyhledávání: '"H. Hellén"'
Autor:
H. Hellén, R. Kouznetsov, K. Kraft, J. Seppälä, M. Vestenius, J.-P. Jalkanen, L. Laakso, H. Hakola
Publikováno v:
Atmospheric Chemistry and Physics, Vol 24, Pp 4717-4731 (2024)
The mixing ratios of highly volatile organic compounds (VOCs) were studied on Utö Island in the Baltic Sea. Measurements of non-methane hydrocarbons (NMHCs) and methanethiol (unexpectedly found during the experiment) were conducted using an in situ
Externí odkaz:
https://doaj.org/article/b566f17352c54f1f983cc640be5b2098
Publikováno v:
Atmospheric Measurement Techniques, Vol 17, Pp 315-333 (2024)
Biogenic volatile organic compounds (BVOCs; e.g. terpenes) are highly reactive compounds typically present at sub-parts-per-billion mole fractions in the air. Due to this, their measurements are challenging and they may suffer losses during sampling,
Externí odkaz:
https://doaj.org/article/e0071254b9874814ac9683d6f1f8deee
Publikováno v:
Atmospheric Chemistry and Physics, Vol 23, Pp 14627-14642 (2023)
Biogenic volatile organic compounds (BVOCs) are continuously emitted from terrestrial vegetation into the atmosphere and react with various atmospheric oxidants, with ozone being an important one. The reaction between BVOCs and ozone can lead to low
Externí odkaz:
https://doaj.org/article/3460984b10b14003ae9cd64a548e66cd
Autor:
M. Okuljar, O. Garmash, M. Olin, J. Kalliokoski, H. Timonen, J. V. Niemi, P. Paasonen, J. Kontkanen, Y. Zhang, H. Hellén, H. Kuuluvainen, M. Aurela, H. E. Manninen, M. Sipilä, T. Rönkkö, T. Petäjä, M. Kulmala, M. Dal Maso, M. Ehn
Publikováno v:
Atmospheric Chemistry and Physics, Vol 23, Pp 12965-12983 (2023)
Condensable vapors, including highly oxygenated organic molecules (HOMs), govern secondary organic aerosol formation and thereby impact the quantity, composition, and properties (e.g., toxicity) of aerosol particles. These vapors are mainly formed in
Externí odkaz:
https://doaj.org/article/43b86298aad848948e60996a69fade7b
Autor:
S. Saarikoski, H. Hellén, A. P. Praplan, S. Schallhart, P. Clusius, J. V. Niemi, A. Kousa, T. Tykkä, R. Kouznetsov, M. Aurela, L. Salo, T. Rönkkö, L. M. F. Barreira, L. Pirjola, H. Timonen
Publikováno v:
Atmospheric Chemistry and Physics, Vol 23, Pp 2963-2982 (2023)
Urban air consists of a complex mixture of gaseous and particulate species from anthropogenic and biogenic sources that are further processed in the atmosphere. This study investigated the characteristics and sources of volatile organic compounds (VO
Externí odkaz:
https://doaj.org/article/c7d59f3d19694aea90498123dcea9821
Publikováno v:
Atmospheric Chemistry and Physics, Vol 21, Pp 14761-14787 (2021)
The East African lowland and highland areas consist of water-limited and humid ecosystems. The magnitude and seasonality of biogenic volatile organic compounds (BVOCs) emissions and concentrations from these functionally contrasting ecosystems are li
Externí odkaz:
https://doaj.org/article/9560a044c5a54c548de11a715a18b619
Autor:
H. Hellén, A. P. Praplan, T. Tykkä, A. Helin, S. Schallhart, P. P. Schiestl-Aalto, J. Bäck, H. Hakola
Publikováno v:
Atmospheric Chemistry and Physics, Vol 21, Pp 8045-8066 (2021)
Biogenic volatile organic compounds (BVOCs) emitted by the forests are known to have strong impacts in the atmosphere. However, lots of missing reactivity is found, especially in the forest air. Therefore better characterization of sources and identi
Externí odkaz:
https://doaj.org/article/438787a9b663419787299493c0a1a163
Publikováno v:
Biogeosciences, Vol 17, Pp 4681-4705 (2020)
In forested area, a large fraction of total hydroxyl radical (OH) reactivity remains unaccounted for. Very few studies have looked at the variations in total OH reactivity from biogenic emissions. In the present study, we investigate the total OH rea
Externí odkaz:
https://doaj.org/article/7402c4fdf577450cb43006013f0f19d1
Publikováno v:
Atmospheric Measurement Techniques, Vol 13, Pp 3543-3560 (2020)
In this study, a thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) method following sorbent tube sampling was developed for the determination of monoterpenes (MTs), sesquiterpenes (SQTs) and diterpenes (DTs) in gas-phase samp
Externí odkaz:
https://doaj.org/article/5216d4e33a8a438fa80d687a978bac62
Publikováno v:
Atmospheric Chemistry and Physics, Vol 20, Pp 7021-7034 (2020)
We have studied biogenic volatile organic compound (BVOC) emissions and their ambient concentrations at a sub-Arctic wetland (Lompolojänkkä, Finland), which is an open, nutrient-rich sedge fen and a part of the Pallas-Sodankylä Global Atmosphere W
Externí odkaz:
https://doaj.org/article/14bce8a399fb41c9a9b1b45de8f0ff9e