Aerozolio dalelių atliekama šviesos sklaida ir sugertis, vyraujant skirtingiems šaltiniams, Lietuvoje

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Office Indoor PM and BC Level in Lithuania: The Role of a Long-Range Smoke Transport Event

While the impacts of climate change on wildfires and resulting air pollution levels have been observed, little is known about how indoor air filtering systems are performing under intensive smoke conditions. For this aim, particle number size distribution and concentration in a size range 0.5–18 μm and equivalent black carbon (eBC) mass concentration were measured in a modern office with a mechanical ventilation system. Measurements took place from 30 September to 6 October 2020 in the Center for Physical Sciences and Technology (FTMC) campus located in the urban background environment in Lithuania. During the measurement campaign, an intensive pollution episode, related to long-range transport wildfire smoke, was observed. The results indicated that the smoke event increased both indoor and outdoor eBC mass concentrations twice. Filters were non-selective for different eBC sources (biomass burning versus traffic) or chemical composition of carbonaceous aerosol particles (eBC versus brown carbon (BrC)). Air filtering efficiency was found to be highly dependent on particle size. During the smoke event the highest particle number concentration was observed at 2.1 μm and 1.0 μm size particles in outdoor and indoor air, respectively. Differences of indoor to outdoor ratio between event and non-event days were not significant. Because of lower removal rate for small particles, eBC had higher contribution to total PM2.5 mass concentration in indoor air than in outdoor air. The results gained are crucial for decision-making bodies in order to implement higher-quality air-filtering systems in office buildings and, as a result, minimize potential health impacts. © 2021 by the authors

Estimation of Carbonaceous Aerosol Sources under Extremely Cold Weather Conditions in an Urban Environment

The present study investigated the characteristics of carbonaceous species in an urban background site. Real-time measurements of inorganic (sulfate, nitrate, ammonium, chloride, and black carbon [BC]) and organic submicron aerosols (OA) were carried out at the urban background site of Vilnius, Lithuania, during January–February 2014. An aerosol chemical speciation monitor (ACSM, Aerodyne Research Inc., Billerica, MA, USA) and co-located 7-λ aethalometer (AE-31, Magee Scientific, Berkeley, CA, USA) were used to analyze the chemical compositions, sources, and extinction characteristics of the PM1. Extremely contrasting meteorological conditions were observed during the studied period due to the transition from moderately cold (~2 °C) conditions to extremely cold conditions with a lowest temperature of −25 °C; therefore, three investigation episodes were considered. The identified periods corresponded to the transition time from the moderately cold to the extremely cold winter period, which was traced by the change in the average temperature for the study days of 1–13 January, with T = −5 °C and RH = 92%, in contrast to the period of 14–31 January, with T = −14 °C and RH = 74%, and the very short third period of 1–3 February, with T = −8 °C and RH = 35%. On average, organics accounted for the major part (53%) of the non-refractory submicron aerosols (NR-PM1), followed by nitrate (18%) and sulfate (9%). The source apportionment results showed the five most common OA components, such as traffic and heating, to be related to hydrocarbon-like organic aerosols (HOAtraffic and HOAheating, respectively), biomass-burning organic aerosols (BBOA), local organic aerosol (LOA), and secondary organic aerosol (SOA). Traffic emissions contributed 53% and biomass burning 47% to the BC concentration level. The highest BC and OA concentrations were, on average, associated with air masses originating from the southwest and east–southeast. Furthermore, the results of the PSCF and CWT methods indicated the main source regions that contributed the most to the BC concentration in Vilnius to be the following: central–southwestern and northeastern Poland, northwestern–southwestern and eastern Belarus, northwestern Ukraine, and western Russia. However, the potential sources of OA were widely distributed

Observations of new particle formation events in the south-eastern Baltic Sea

New particle formation and growth were observed at a coastal site (Preila station, Lithuania) during 1997 and 2000-2002. The total amountof data analysed covers 291 one-day periods, 45 (15%) of which were long-term, new particle formation days. Short-term nucleationevents (from a few minutes to one hour) and long-term events (from one to eight hours) were identified. The mean particlegrowth rate, condensation sink and condensable vapour source rate during nucleation events were 3.9 nm h^-1, 1.45 × 10^-3 cm^-3 s^-1 and 7.5 × 10⁴ cm^-3 s^-1 respectively.The average formation rate <i>J</i>₁₀ was 0.4 cm^-3 s^-1. The nucleation events were accompaniedmainly by air masses transported from the north (43%) and north-west (19%). Meteorological parameters and trace gas (O₃, SO₂,NO₂) concentrations were also analysed. It was found that nucleation events are related to high levels of solar radiation

Abiotinio streso įtaka aerozolio dalelių masės spektrui miško aplinkoje Lietuvoje

Abiotinio streso veikiami medžiai išskiria lakius organinius junginius (LOJ), kurie yra antrinių aerozolio dalelių (SOA) prekursoriai. Tyrimo tikslas buvo atlikti submikroninių aerozolio dalelių (PM1) masės koncentracijos tyrimus ir šaltinių kilmės atskyrimą medžių abiotinio streso sąlygomis formuojantis SOA. Aerozolio cheminė sudėtis Aukštaitijos integruotoje monitoringo stotyje (IMS LT01) rytinėje Lietuvos dalyje mišraus miško aplinkoje buvo išmatuota aerozolio cheminės sudėties monitoriumi (ACSM). Nustatyta, kad PM1 organikos frakcija sudaryta iš antrinių (76 %) ir pirminių (24 %) aerozolio dalelių. Medžio kamieno skersmens pokyčių analizė parodė tris medžio kamieno skersmens augimo ir susitraukimo epizodus. Esant abiotinio streso sąlygoms, vyksta medžių kamienų skersmens susitraukimo epizodai, todėl išauga m/z 42, 43, 45, 48 ir 50 signalų intensyvumai nuo 5,7 iki 8,8 kartų, o SOA paros koncentracija padidėja nuo 2,7 iki 4,7 kartų. Įprastai augant medžio kamieno skersmeniui m/z signalų intensyvumai ir SOA koncentracija nekinta. Galima teigti, kad augalų patiriamo abiotinio streso atsakas gali būti identifikuojamas per nustatytų m/z signalų intensyvumų pokyčius ir lemti padidėjusią SOA koncentracijąVolatile organic compounds (VOCs) emitted by trees in response to abiotic stress evoke high levels of secondary organic aerosol (SOA) compounds. Few techniques exist to provide chemically-resolved submicron (PM1) particle mass concentrations and source apportionment of stress-induced emissions from trees and SOA formation. The chemical composition of atmospheric aerosol particles was characterized using an aerosol chemical speciation monitor (ACSM) at a mixed-mature forest site – the Aukštaitija Integrated Monitoring Station in the eastern part of Lithuania. The organic fraction of PM1 consisted of SOA (76%) and of anthropogenic combustion related primary organic aerosol (POA) (24%). The analysis of tree trunk circumference revealed three shrinkage and three normal increase episodes. During the episodes of tree trunk circumference shrinkage, several m/z signal (m/z 42, 43, 45, 48, 50) intensities were found to be magnified together with the daily SOA concentration. The stress response analysis confirm that tree trunk circumference shrinkage may be observed through the enhancement of selected m/z signals and result in increased SOA levelsFizinių ir technologijos mokslų centrasMiškų ir ekologijos fakultetasVytauto Didžiojo universitetasŽemės ūkio akademij