A5076457575- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Plant responses to elevated CO2
- Air Quality Monitoring and Forecasting
- Air Quality and Health Impacts
- Odor and Emission Control Technologies
- Indoor Air Quality and Microbial Exposure
- Atmospheric aerosols and clouds
- Lichen and fungal ecology
- Vehicle emissions and performance
- Methane Hydrates and Related Phenomena
- Plant Water Relations and Carbon Dynamics
- Environmental Policies and Emissions
- Peatlands and Wetlands Ecology
- Urban Heat Island Mitigation
- Advanced Chemical Sensor Technologies
- Geological Studies and Exploration
- Botany and Plant Ecology Studies
- Species Distribution and Climate Change
- Analytical Chemistry and Sensors
- Marine and coastal ecosystems
- Isotope Analysis in Ecology
- Spectroscopy and Laser Applications
- Metal-Catalyzed Oxygenation Mechanisms
University of Helsinki
2015-2024
Helsinki Institute of Physics
2011-2017
Atmospheric nucleation is the dominant source of aerosol particles in global atmosphere and an important player climatic effects. The key steps this process occur sub-2-nanometer (nm) size range, which direct size-segregated observations have not been possible until very recently. Here, we present detailed atmospheric nanoparticles clusters down to 1-nm mobility diameter. We identified three separate regimes below 2-nm diameter that build up a physically, chemically, dynamically consistent...
Abstract. The impact of aerosols on climate and air quality remains poorly understood due to multiple factors. One the current limitations is incomplete understanding contribution oxygenated products, generated from gas-phase oxidation volatile organic compounds (VOCs), aerosol formation. Indeed, atmospheric gaseous chemical processes yield thousands (highly) species, spanning a wide range formulas, functional groups and, consequently, volatilities. While recent mass spectrometric...
Abstract Over Boreal regions, monoterpenes emitted from the forest are main precursors for secondary organic aerosol (SOA) formation and primary driver of growth new particles to climatically important cloud condensation nuclei (CCN). Autoxidation leads rapid Highly Oxygenated Molecules (HOM). We have developed first model with near-explicit representation atmospheric particle (NPF) HOM formation. The can reproduce observed NPF, gas-phase composition SOA over forest. During spring, increases...
Abstract Intense and frequent new particle formation (NPF) events have been observed in polluted urban environments, yet the dominant mechanisms are still under debate. To understand key species governing processes of NPF we conducted comprehensive measurements downtown Beijing during January–March, 2018. We performed detailed analyses on sulfuric acid cluster composition budget, as well chemical physical properties oxidized organic molecules (OOMs). Our results demonstrate that fast...
Abstract. Ambient total OH reactivity was measured at the Finnish boreal forest station SMEAR II in Hyytiälä (Latitude 61°51' N; Longitude 24°17' E) July and August 2010 using Comparative Reactivity Method (CRM). The CRM – method is a direct, in-situ determination of loss rate hydroxyl radicals (OH) caused by all reactive species air. During intensive field campaign HUMPPA-COPEC (Hyytiälä United Measurements Photochemistry Particles Air Comprehensive Organic Precursor Emission Concentration...
Abstract. This paper describes the background, instrumentation, goals, and regional influences on HUMPPA-COPEC intensive field measurement campaign, conducted at Boreal forest research station SMEAR II (Station for Measuring Ecosystem-Atmosphere Relation) in Hyytiälä, Finland from 12 July–12 August 2010. The prevailing meteorological conditions during campaign are examined contrasted with those of past six years. Back trajectory analyses show that site 2010 were characterized by a higher...
Abstract. The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) are reported for first time based on ambient measurements. With deployment PTR-TOF, we present an overview observed gas-phase (oxygenated) molecules in French Landes forest during summertime 2018 and gain insights into atmospheric oxidation terpenes, which emitted large quantities atmosphere play important roles secondary organic aerosol production. Due to greatly...
Abstract Oxidation chemistry controls both combustion processes and the atmospheric transformation of volatile emissions. In engines, radical species undergo isomerization reactions that allow fast addition O 2 . This chain reaction, termed autoxidation, is enabled by high engine temperatures, but has recently been also identified as an important source for highly oxygenated in atmosphere, forming organic aerosol. Conventional knowledge suggests autoxidation requires suitable structural...
Abstract. Atmospheric organic vapors play essential roles in the formation of secondary aerosol. Source identification these is thus fundamental to understanding their emission sources and chemical evolution atmosphere further impact on air quality climate change. In this study, a Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) was deployed two forested environments, Landes forest southern France boreal Finland, measure atmospheric vapors, including both volatile...
Abstract. Wetlands cover only 3 % of the global land surface area, but boreal wetlands are experiencing an unprecedented warming four times average. These emit isoprene and terpenes (including monoterpenes (MT), sesquiterpenes (SQT), diterpenes (DT)), which climate-relevant highly reactive biogenic volatile organic compounds (BVOCs) with exponential dependence on temperature. In this study, we present ecosystem-scale eddy covariance (EC) fluxes isoprene, MT, SQT, DT (hereafter referred to...
Abstract. Long-term flux measurements of volatile organic compounds (VOC) over boreal forests are rare, although the known to emit considerable amounts VOCs into atmosphere. Thus, we measured fluxes several and oxygenated a Scots-pine-dominated forest semi-continuously between May 2010 December 2013. The VOC profiles were obtained with proton transfer reaction mass spectrometry, calculated using vertical concentration surface layer profile method connected Monin-Obukhov similarity theory. In...
The understanding at a molecular level of ambient secondary organic aerosol (SOA) formation is hampered by poorly constrained mechanisms and insufficient analytical methods. Especially in developing countries, SOA related haze great concern due to its significant effects on climate human health. We present simultaneous measurements gas-phase volatile compounds (VOCs), oxygenated molecules (OOMs), particle-phase Beijing. show that condensation the measured OOMs explains 26–39% mass growth,...
Abstract. We evaluate monoterpene-derived peroxy radical (MT-RO2) unimolecular autoxidation and self- cross-reactions with other RO2 species in the GEOS-Chem global chemical transport model. The formation of associated highly oxygenated organic molecules (HOMs) accretion products are tracked competition bimolecular reactions. Autoxidation is dominant fate up to 6–8 km for first-generation MT-RO2, which can undergo H shifts. Reaction NO be a more common H-shift rate constants < 0.1 s−1 or...
Abstract Eddy covariance fluxes of formic acid, HCOOH, were measured over a boreal forest canopy in spring/summer 2014. The HCOOH bidirectional but mostly upward during daytime, contrast to studies elsewhere that reported downward fluxes. Downward flux episodes explained well by modeled dry deposition rates. sum net observed and yields an “gross flux” which could not be quantitatively literature estimates direct vegetative/soil emissions nor efficient chemical production from other volatile...
Solar eclipses provide unique possibilities to investigate atmospheric processes, such as new particle formation (NPF), important the global aerosol load and radiative balance. The temporary absence of solar radiation gives particular insight into different oxidation clustering processes leading NPF. This is crucial because our mechanistic understanding on how NPF related photochemistry still rather limited. During a partial eclipse over Finland in 2015, we found that this phenomenon had...
Abstract. The Station for Measuring Ecosystem–Atmosphere Relations (SMEAR) II is well known among atmospheric scientists due to the immense amount of observational data it provides Earth–atmosphere interface. Moreover, SMEAR plays an important role large European research infrastructure, enabling scientific community tackle climate- and air-pollution-related questions, utilizing high-quality long-term sets recorded at site. So far, this well-documented site was missing description seasonal...
Abstract. Monoterpene emissions from Scots pine have traditionally been assumed to originate as evaporation specialized storage pools. More recently, the significance of de novo emissions, originating directly monoterpene biosynthesis, has recognized. To study role biosynthesis at ecosystem scale, we measured a dominated forest in southern Finland using disjunct eddy covariance method combined with proton transfer reaction mass spectrometry. The interpretation measurements was based on...
Abstract. We measured volatile organic compounds (VOCs), carbon dioxide (CO2) and monoxide (CO) at an urban background site near the city centre of Helsinki, Finland, northern Europe. The VOC CO2 measurements were obtained between January 2013 September 2014 whereas for CO a shorter measurement campaign in April–May was conducted. Both anthropogenic biogenic sources identified VOCs study. Strong correlations fluxes traffic rates indicated source many VOCs. with highest emission rate to...
Abstract. The eddy covariance (EC) technique is the most direct method for measuring exchange between surface and atmosphere in different ecosystems. Thus, it commonly used to get information on air pollutant greenhouse gas emissions, turbulent heat transfer. Typically an ecosystem monitored by only one single EC measurement station at a time, making ecosystem-level flux values subject random systematic uncertainties. Furthermore, urban ecosystems we often have no choice but conduct...
Abstract. The metallurgical industry in the Kola Peninsula, north-west Russia, form, after Norilsk, Siberia, second largest source of air pollution Arctic and subarctic domain. Sulfur dioxide (SO2) emissions from ore smelters are transported to wide areas, including Finnish Lapland. We performed investigations on concentrations SO2, aerosol precursor vapours, ion cluster size distributions together with chemical composition measurements freshly formed clusters at SMEAR I station Lapland...
Abstract Aerosols and their interaction with clouds constitute the largest uncertainty in estimating radiative forcing affecting climate system. Secondary aerosol formation is responsible for a large fraction of cloud condensation nuclei global atmosphere. Wetlands are important to budgets methane carbon dioxide, but potential role wetlands has not been investigated. Here we use direct atmospheric sampling at Siikaneva wetland Finland investigate emission volatile organic compounds,...
Abstract. The oxidation products of monoterpenes likely have a crucial role in the formation and growth aerosol particles boreal forests. However, continuous measurements monoterpene concentrations are usually not available on decadal timescales, direct product so far been scarce. In this study we developed proxies for their at forest site Hyytiälä, southern Finland. For deriving used concentration measured with proton transfer reaction mass spectrometer (PTR-MS) during 2006–2013. Our take...
Abstract. Between April and June 2013 fluxes of volatile organic compounds (VOCs) were measured in a Scots pine Norway spruce forest using the eddy covariance (EC) method with proton transfer reaction time-of-flight (PTR-TOF) mass spectrometer. The observations performed above boreal at SMEAR II site southern Finland.We found total 25 different exchange investigated their seasonal variations from spring to summer. majority net VOC flux was comprised methanol, monoterpenes, acetone butene +...
Abstract. This paper reports the fluxes and mixing ratios of biogenically emitted volatile organic compounds (BVOCs) 4 m above a mixed oak hornbeam forest in northern Italy. Fluxes methanol, acetaldehyde, isoprene, methyl vinyl ketone + methacrolein, ethyl monoterpenes were obtained using both proton-transfer-reaction mass spectrometer (PTR-MS) time-of-flight (PTR-ToF-MS) together with methods virtual disjunct eddy covariance (using PTR-MS) PTR-ToF-MS). Isoprene was dominant compound mean...