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Alternating Photochemical and dark ageing of biomass burning plumes in the Large Aerosol Chamber (PHOTO-LAC)тезисы доклада
- Авторы: Czech H., Popovicheva O.B., Chernov D., Kozlov A.S., Schneider E., Sueur M., Shmargunov V.P., Afonso C., Rüger C.P., Zimmermann R.
- Сборник: European Aerosol Conference 2023 (EAC2023)
- Тезисы
- Год издания: 2023
- Место издания: Malaga
- Первая страница: Poster−1: 5.01#1
- Аннотация: Plumes from wildfires may be transported over largedistances from remote to populated areas or threatensensitive ecosystems. During atmospheric transport,plumes are processed by atmospheric oxidants andcomplex multiphase chemistry. At high plumeconcentrations, ageing of biomass burning (BB) aerosoldiffer from its atmospheric fate at typical ambient levels(Decker et al 2021).The Large Aerosol Chamber for photochemicalageing (PHOTO-LAC) with a volume of 1,800 m3 was usedto investigate the chemical composition of fresh andaged dense biomass burning aerosols. The PHOTO-LACcontains two ovens enabling the generation of aerosolsunder flaming and smouldering conditions. (Popovichevaet al, 2016). Equivalent particulate matter (ePM) andreactive gases O3 and NOx, were monitored by a multiangle/ multi-wavelength nephelometer and gasanalysers, respectively. Filter samples were collected onquartz fibre filter and analysed by Fourier-transform IonCyclotron Resonance Mass Spectrometry (FT-ICR MS). Inthe following, we describe the effect of alternatingphotochemical and dark plume ageing of pine flamingand smouldering aerosol, resembling day- and night-timeconditions over a total experimental duration of 30 h.After conversion of NO into NO2 by O3 addition,UV lights were turned for 7 h, turned off for 13 h andturned on again for 10 h. In both flaming andsmouldering of 300 g pine mixed with 100 g forest debris,ePM decreased by ~15% during photochemical, butreincreased during dark ageing, exceeding initialconcentrations. Eventually, consecutive photochemicalageing increased ePM further to a net increase in ePM of15% for flaming and 35% for smouldering.The chemical composition of the flaming andsmouldering aerosols changed during the entire ageingexperiment by increasing elemental O:C and organicmatter to organic carbon (OM/OC) ratio as well asdecreasing aromaticity. Interestingly, OM/OC increasedwhen ePM declined during first photochemical ageing,hence fragmentation reactions play a significant role.However, secondary PM formation and increasing Ocontent,both well-known for ageing of BB aerosol, areapparently reduced compared to smog chamberexperiments at levels closer to ambient PM (Tiitta et al,2016), emphasising the need of laboratory plume ageingstudies for a better understanding of the atmosphericfate of wildfire plumes
- Добавил в систему: Чичаева Марина Александровна