Hyvin pienten ilmakehän aerosolihiukkasten muodostumisen, kasvun, hygroskooppisuuden ja haihtuvuuden mittaamisesta

Atmospheric aerosol particles affect the global climate as well as human health. In this thesis, formation of nanometer sized atmospheric aerosol particles and their subsequent growth was observed to occur all around the world. Typical formation rate of 3 nm particles at varied from 0.01 to 10 cm-3s-1. One order of magnitude higher formation rates were detected in urban environment. Highest formation rates up to 105 cm-3s-1 were detected in coastal areas and in industrial pollution plumes. Subsequent growth rates varied from 0.01 to 20 nm h-1. Smallest growth rates were observed in polar areas and the largest in the polluted urban environment. This was probably due to competition between growth by condensation and loss by coagulation. Observed growth rates were used in the calculation of a proxy condensable vapour concentration and its source rate in vastly different environments from pristine Antarctica to polluted India. Estimated concentrations varied only 2 orders of magnitude, but the source rates for the vapours varied up to 4 orders of magnitude. Highest source rates were in New Delhi and lowest were in the Antarctica. Indirect methods were applied to study the growth of freshly formed particles in the atmosphere. Also a newly developed Water Condensation Particle Counter, TSI 3785, was found to be a potential candidate to detect water solubility and thus indirectly composition of atmospheric ultra-fine particles. Based on indirect methods, the relative roles of sulphuric acid, non-volatile material and coagulation were investigated in rural Melpitz, Germany. Condensation of non-volatile material explained 20-40% and sulphuric acid the most of the remaining growth up to a point, when nucleation mode reached 10 to 20 nm in diameter. Coagulation contributed typically less than 5%. Furthermore, hygroscopicity measurements were applied to detect the contribution of water soluble and insoluble components in Athens. During more polluted days, the water soluble components contributed more to the growth. During less anthropogenic influence, non-soluble compounds explained a larger fraction of the growth. In addition, long range transport to a measurement station in Finland in a relatively polluted air mass was found to affect the hygroscopicity of the particles. This aging could have implications to cloud formation far away from the pollution sources.Hengittämässämme ilmassa on koko ajan pieniä kiinteitä tai nestemäisiä aerosolihiukkasia, jotka ovat liian pieniä pudotakseen maahan maan vetovoiman vaikutuksesta. Esimerkiksi pölyhitunen on aerosolihiukkanen. Yleisesti aerosolihiukkaset esimerkiksi heikentävät näkyvyyttä ja aiheuttavat hengityselin- ja sydänsairauksia. Lisäksi ne vaikuttavat koko maapallon ilmastoon, koska pilvet muodostuvat aerosolihiukkasten päälle. Ilmakehään aerosolihiukkaset joutuvat esimerkiksi tuulen nostaessa ilmaan aavikon hiekkaa, meren pärskeistä tai erilaisten kaasujen tiivistyessä. Väitöskirjassani tutkin hyvin pienten (halkaisijaltaan alle 100 nm, 1 nanometri on miljoonasosa millimetristä) aerosolihiukkasten muodostumista, kasvua ja ominaisuuksia. Väitöskirjassa kokosin yhteen viimeisten vuosikymmenien aikana tehdyt havainnot eri puolilta maapalloa. Yli sadassa tutkimuksessa havaittiin, että uusia aerosolihiukkasia muodostuu ilmakehässä kaikkialla: esimerkiksi Lapissa, Keski-Euroopassa, saastuneessa New Delhissä ja Antarktiksella. Tarkkaa muodostumismekanismia ei vielä tiedetä. Kaasuista muodostuneet hiukkaset ovat kooltaan niin pieniä, että niiden kemiallista koostumusta on hyvin vaikea mitata. Tässä työssä tarkkailtiin uusien, juuri muodostuneitten hiukkasten ominaisuuksien muutoksia, joka kertoi hiukkasten kemiallisen koostumuksen muutoksista. Mittaukset tehtiin Suomessa, Saksassa, Kreikassa ja Ranskassa. Saastuneessa ilmassa muodostuneitten uusien hiukkasten ominaisuudet poikkesivat puhtaassa ilmassa muodostuneista hiukkasista. Tämä voi puolestaan vaikuttaa esimerkiksi pilvien muodostumiseen ja sateen alueelliseen jakautumiseen

Institute for Atmospheric and Earth System Research (INAR) : Showcases for making science diplomacy

Science diplomacy can be defined as "the use of scientific collaborations between countries to address joint problems and to build constructive international partnerships for delivering effective scientific advice for policy making". During the last 10 years, the Institute for Atmospheric and Earth System Research (INAR) has been active in finding ways to solve global Grand Challenges, particularly climate change and poor air quality in polluted megacities, and at the same time, better bridge research to international climate policy and science diplomacy processes. INAR has introduced Pan-Eurasian Experiment programme running since the year 2012 (www.atm.helsinki.fi/peex) to better address the scientific challenge to understand Atmosphere - Earth Surface - Biosphere interactions and feedbacks in the Northern Eurasian context. INAR has also launched a measurement concept called the Global Network of Stations Measuring Earth Surface and Atmosphere Interactions (GlobalSMEAR) and has hosted the European Centre of the International Eurasian Academy of Sciences since 2015. Most recently, INAR has coordinated the Arena for the gap analysis of the existing Arctic Science Co-Operations (AASCO), 2020-2021, to promote research with a holistic and integrated approach in understanding feedbacks and interactions globally and locally at the Arctic and outside the Arctic environments.Non peer reviewe

Urban Aerosol Particle Size Characterization in Eastern Mediterranean Conditions

Characterization of urban particle number size distribution (PNSD) has been rarely reported/performed in the Middle East. Therefore, we aimed at characterizing the PNSD (0.01–10 µm) in Amman as an example for an urban Middle Eastern environment. The daily mean submicron particle number concentration (PNSub) was 6.5 × 103–7.7 × 104 cm−3 and the monthly mean coarse mode particle number concentration (PNCoarse) was 0.9–3.8 cm−3 and both had distinguished seasonal variation. The PNSub also had a clear diurnal and weekly cycle with higher concentrations on workdays (Sunday–Thursday; over 3.3 × 104 cm−3) than on weekends (below 2.7 × 104 cm−3). The PNSub constitute of 93% ultrafine fraction (diameter < 100 nm). The mean particle number size distributions was characterized with four well-separated submicron modes (Dpg,I, Ni): nucleation (22 nm, 9.4 × 103 cm−3), Aitken (62 nm, 3.9 × 103 cm−3), accumulation (225 nm, 158 cm−3), and coarse (2.23 µm, 1.2 cm−3) in addition to a mode with small geometric mean diameter (GMD) that represented the early stage of new particle formation (NPF) events. The wind speed and temperature had major impacts on the concentrations. The PNCoarse had a U-shape with respect to wind speed and PNSub decreased with wind speed. The effect of temperature and relative humidity was complex and require further investigations

Using in situ GC-MS for analysis of C-2-C-7 volatile organic acids in ambient air of a boreal forest site

An in situ method for studying gas-phase C-2-C-7 monocarboxylic volatile organic acids (VOAs) in ambient air was developed and evaluated. Samples were collected directly into the cold trap of the thermal desorption unit (TD) and analysed in situ using a gas chromatograph (GC) coupled to a mass spectrometer (MS). A polyethylene glycol column was used for separating the acids. The method was validated in the laboratory and tested on the ambient air of a boreal forest in June 2015. Recoveries of VOAs from fluorinated ethylene propylene (FEP) and heated stainless steel inlets ranged from 83 to 123 %. Different VOAs were fully desorbed from the cold trap and well separated in the chromatograms. Detection limits varied between 1 and 130 pptv and total uncertainty of the method at mean ambient mixing ratios was between 16 and 76 %. All straight chain VOAs except heptanoic acid in the ambient air measurements were found with mixing ratios above the detection limits. The highest mixing ratios were found for acetic acid and the highest relative variations for hexanoic acid. In addition, mixing ratios of acetic and propanoic acids measured by the novel GC-MS method were compared with proton-mass-transfer time-off-light mass spectrometer (PTR-TOFMS) data. Both instruments showed similar variations, but differences in the mixing ratio levels were significant.Peer reviewe

Enviro-HIRLAM model estimates of elevated black carbon pollution over Ukraine resulted from forest fires

Funding Information: The study is part of the Enviro–PEEX on the ECMWF (Pan-Eurasian Experiment (PEEX; https://www.atm.helsinki.fi/peex , last access: last access: 8 December 2022) Modelling Platform research and development of online coupled integrated meteorology–chemistry–aerosols feedback and interactions in weather, climate, and atmospheric composition multi-scale modelling) project (2018–2020). The Enviro-HIRLAM model simulations were performed on the CSC (Center for Science Computing) Sisu HPC (Finland) during the Enviro-HIRLAM and HARMONIE research training course at the Institute for Atmospheric and Earth System Research (INAR) of the University of Helsinki (UHEL). The authors also gratefully acknowledge the computer resources and technical support provided by the Center for Science Computing (CSC) HPC (Finland). This study was carried out within the framework of the State Emergency Service of Ukraine and National Academy of Sciences of Ukraine. The work has been partially supported by Academy of Finland via a Flagship programme for Atmospheric and Climate Competence Center (ACCC, 337549) and Academy of Finland projects (334792, 328616, 345510) and European Commission via a project “Non-CO Forcers and Their Climate, Weather, Air Quality and Health Impacts”, (FOCI) and the project “Research Infrastructures Services Reinforcing air quality monitoring capacities in European URBAN & Industrial areaS” (RI-URBANS), no. 101036245. Funding Information: This research has been supported by a grant within the ENVRIplus project for multi-domain access to RI platforms (H2020-INFRAIA-2014-2015, grant no.: 654182). The work has been partially performed under the Project HPC-EUROPA3 (INFRAIA-2016-1-730897) with the support of the EC Research Innovation Action under the H2020 Programme. Publisher Copyright: © 2022 Copernicus GmbH. All rights reserved.Biomass burning is one of the biggest sources of atmospheric black carbon (BC), which negatively impacts human health and contributes to climate forcing. In this work, we explore the horizontal and vertical variability of BC concentrations over Ukraine during wildfires in August 2010. Using the Enviro-HIRLAM modelling framework, the BC atmospheric transport was modelled for coarse, accumulation, and Aitken mode aerosol particles emitted by the wildfire. Elevated pollution levels were observed within the boundary layer. The influence of the BC emissions from the wildfire was identified up to 550hPa level for the coarse and accumulation modes and at distances of about 2000km from the fire areas. BC was mainly transported in the lowest 3km layer and mainly deposited at night and in the morning hours due to the formation of strong surface temperature inversions. As modelling is the only available source of BC data in Ukraine, our results were compared with ground-level measurements of dust, which showed an increase in concentration of up to 73% during wildfires in comparison to average values. The BC contribution was found to be 10%-20% of the total aerosol mass near the wildfires in the lowest 2km layer. At a distance, BC contribution exceeded 10% only in urban areas. In the areas with a high BC content represented by both accumulation and coarse modes, downwelling surface long-wave radiation increased up to 20Wm-2, and 2m air temperature increased by 1-4°C during the midday hours. The findings of this case study can help to understand the behaviour of BC distribution and possible direct aerosol effects during anticyclonic conditions, which are often observed in mid-latitudes in the summer and lead to wildfire occurrences.Peer reviewe

Electric charge of atmospheric nanoparticles and its potential implications with human health

This research presents a pilot project developed within the framework of the COST Action 15,211 in which atmospheric nanoparticles were measured in July 2018, in a maritime environment in the city of Santander in Northern Spain. ELPI (R) + (Electrical low-Pressure Impactor) was used to measure nanoparticle properties (electric charge, number, size distribution and surface area) from 6 nm to 10,000 nm with 14 size channels. This study focused on the range between 6 and 380 nm. It considered atmospheric nanoparticle electric charge with surface area, deposited and number by size distribution at human respiratory tract regions in a standard person in Santander according to the human respiratory tract model of ICRP 94. An empirical distribution of nanoparticles deposited in the human respiratory tract model and its electric charge is presented for the city of Santander as the main output. Percentages of total and regional deposition in human respiratory tract model were calculated for the Atlantic climate. Nanoparticles have shown an alveolar surface area deposition plateau with a size distribution range between 6 nm to 150 nm. Negative charge of nanoparticles was clearly associated with primary atmospheric nanoparticles being mainly deposited in the alveolar region where a Brownian mechanism of deposition is predominant. We can demonstrate that electric charge may be a key element in explaining Brownian deposition of the smallest particles in the human respiratory tract and that it can be linked to theoretical positive and negative impacts on human health according to several biometeorological studies. To support our analysis, aerosol samples were characterized with transmission electron microscopy and Confocal Raman spectrometer to determinate morphology, size, chemical composition, and structure. The toxicological effects of the samples with the alveolar surface area had a greater deposition, remain to be studied.Peer reviewe

Should we further investigate the cascading effects of introduced fish on insectivorous birds?

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Mobile ground-based measurements of aerosol and trace gases during a prescribed burning experiment in boreal forest in Finland

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