Mika Vestenius - Academia.edu (original) (raw)
Papers by Mika Vestenius
Shipping and algae emissions have a major impact on ambient air mixing ratios of non-methane hydrocarbons (NMHCs) and methanethiol on Utö Island in the Baltic Sea
Atmospheric chemistry and physics, Apr 19, 2024
Biogeosciences, Apr 10, 2012
Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from vario... more Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from various natural sources. Damaging the plant tissue is known to strongly increase their monoterpene release. We measured the terpenoid emissions caused by timber felling, i.e. those from stumps and logging residue. The emissions from stumps were studied using enclosures and those from the whole felling area using an ecosystem-scale micrometeorological method, disjunct eddy accumulation (DEA). The compounds analyzed were isoprene, monoterpenes and sesquiterpenes. Strong emissions of monoterpenes were measured from both the stumps and from the whole felling area. The emission rate decreased rapidly within a few months after the logging. In addition to fresh logging residue, the results suggest also other strong monoterpene sources may be present in the felling area. These could include pre-existing litter, increased microbial activity and remaining undergrowth. In order to evaluate the possible importance of monoterpenes emitted annually from cut Scots pine forests in Finland, we conducted a rough upscaling calculation. The resulting monoterpene release was approximated to be on the order of 15 kilotonnes per year, which corresponds to about one tenth of the monoterpene release from intact forests in Finland.
Supplement figures S1 and S2 show the monthly variation of BaP and levoglucosan concentrations at... more Supplement figures S1 and S2 show the monthly variation of BaP and levoglucosan concentrations at different stations in 20 Helsinki metropolitan area together with monthly mean temperatures at Kumpula weather station in Helsinki in 2007-2015.
Even though emission inventories indicate that wood combustion is a major source of polycyclic ar... more Even though emission inventories indicate that wood combustion is a major source of polycyclic aromatic hydrocarbons (PAHs), estimating its impacts on PAH concentration in ambient air remains challenging. In this study the effect of local small-scale wood combustion on the benzo[a]pyrene (BaP) concentrations in ambient air in the Helsinki metropolitan area in Finland is evaluated, using ambient air measurements, emission estimates, and dispersion modeling. The measurements were conducted at 12 different locations during the period from 2007 to 2015. The spatial distributions of annual average BaP concentrations originating from wood combustion were predicted for four of those years: 2008, 2011, 2013, and 2014. According to both the measurements and the dispersion modeling, the European Union target value for the annual average BaP concentrations (1 ng m −3) was clearly exceeded in certain suburban detached-house areas. However, in most of the other urban areas, including the center of Helsinki, the concentrations were below the target value. The measured BaP concentrations highly correlated with the measured levoglucosan concentrations in the suburban detached-house areas. In street canyons, the measured concentrations of BaP were at the same level as those in the urban background, clearly lower than those in suburban detached-house areas. The predicted annual average concentrations matched with the measured concentrations fairly well. Both the measurements and the modeling clearly indicated that wood combustion was the main local source of ambient air BaP in the Helsinki metropolitan area.
![Research paper thumbnail of Evaluation of the impact of wood combustion on benzo[<i>a</i>]pyrene (BaP) concentrations; ambient measurements and dispersion modeling in Helsinki, Finland](https://attachments.academia-assets.com/116897091/thumbnails/1.jpg)
](Atmospheric Chemistry and Physics, Mar 10, 2017
Even though emission inventories indicate that wood combustion is a major source of polycyclic ar... more Even though emission inventories indicate that wood combustion is a major source of polycyclic aromatic hydrocarbons (PAHs), estimating its impacts on PAH concentration in ambient air remains challenging. In this study the effect of local small-scale wood combustion on the benzo[a]pyrene (BaP) concentrations in ambient air in the Helsinki metropolitan area in Finland is evaluated, using ambient air measurements, emission estimates, and dispersion modeling. The measurements were conducted at 12 different locations during the period from 2007 to 2015. The spatial distributions of annual average BaP concentrations originating from wood combustion were predicted for four of those years: 2008, 2011, 2013, and 2014. According to both the measurements and the dispersion modeling, the European Union target value for the annual average BaP concentrations (1 ng m −3) was clearly exceeded in certain suburban detached-house areas. However, in most of the other urban areas, including the center of Helsinki, the concentrations were below the target value. The measured BaP concentrations highly correlated with the measured levoglucosan concentrations in the suburban detached-house areas. In street canyons, the measured concentrations of BaP were at the same level as those in the urban background, clearly lower than those in suburban detached-house areas. The predicted annual average concentrations matched with the measured concentrations fairly well. Both the measurements and the modeling clearly indicated that wood combustion was the main local source of ambient air BaP in the Helsinki metropolitan area.
Assessment of the spatial and temporal distribution of persistent organic pollutants (POPs) in the Nordic atmosphere
Atmospheric Environment, Sep 1, 2016
Atmospheric Environment, Jun 1, 2011
Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambien... more Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambient air] at Virolahti, Finland. The sampling site is located in a rural area in the southeastern corner of Finland, near the Russian border. Altogether, 51 daily and 85 weekly filter samples were collected in 2007e2008. The yearly average concentration of benzo(a)pyrene at Virolahti in 2007 was 0.21 ng m À3 , which is well below the annual target value of 1 ng m À3 set by the European Union. The positive matrix factorization (PMF) method was applied in source apportionment for daily PAH data combined with other pollutant data. A three-factor solution of the PMF analysis with 28 components was chosen. These three factors were identified as long-range transported secondary particles (F1), combustion (F2) and a sea-salt factor (F3). The conditional probability function (CPF) was used to combine wind direction sectors with the PMF factors. In cases F1 and F2, pollutants mainly originated from the southeast , whereas pollutants in F3 came from the southwestern sector. PAHs entered into the combustion factor 2 together with SO 2 , NO x , black carbon and potassium. This suggests that the PAHs at Virolahti originated from traffic and industrial pollution, as well as biomass burning. Elevated concentrations occurred throughout the winter period and most frequently originated from the southeastern sector between 90 e135. This sector includes, among other transboundary areas, the metropolis of St. Petersburg at a distance of 160 km.
Atmospheric aerosols local–regional discrimination for a semi-urban area in India
Atmospheric Research, Feb 1, 2016
Abstract In the European Integrated project on Aerosol Cloud Climate and Air Quality interactions... more Abstract In the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI), measurements were carried out with a sequential filter-based aerosol sampler and on-line instruments for aerosol composition and behaviour at Gual Pahari, close to New Delhi. In fine mode (PM 2.5 ), the secondary organic carbon (SOC) to total organic carbon ratio was 46%. This indicated that condensation of SOC on fine size particles could occur rapidly which may be related to the growth of aerosols and the potential to the size of cloud condensation nuclei in the region. Source region discrimination was improved significantly through coupling conditional probability functions with receptor modelling, and validation through volume size distribution. The air masses from industrial and dense populated regions show a mix of local as well as regional emissions to fine mode aerosols. The back-trajectory analysis captured the long-range transport of sea-salt aerosols enriched with mineral dust. The surface wind directions identified the influence of local emission activities.
Effect of the framework charge density on zeolite ion exchange selectivities
Physical Chemistry Chemical Physics, 2000
The ion exchange selectivity of zeolites has been reassessed by calculations with dielectric theo... more The ion exchange selectivity of zeolites has been reassessed by calculations with dielectric theory. For uni–univalent Na+/K+ and Na+/Rb+ exchanges, the observed selectivities, measured as thermodynamic equilibrium constants, decreased with increasing zeolite aluminium content and charge density. For uni–divalent Na+/Ca2+ and Na+/Sr2+ exchanges, the observed trend was the opposite, the selectivities increased with increasing zeolite charge density. Dielectric theory predicts these trends. Moreover, the quantitative agreement with the theory and observed thermodynamic equilibrium constants is good or fair at low charge densities. This agreement is better than what could be anticipated from previous studies of zeolite selectivities. Dielectric theory clearly fails, however, at higher zeolite charge densities.
Atmospheric Environment, 2018
Journal of Aerosol Science, Jul 1, 2014
Globally more than a quarter of the total primary energy supply is based on coal combustion. The ... more Globally more than a quarter of the total primary energy supply is based on coal combustion. The emissions of coal-fired power plants (CFPPs) are regulated in many industrialized countries and therefore power plants use cleaning techniques to minimize emissions such as sulfur dioxide (SO 2) and particles. In this study, the particulate emissions from coal combustion were investigated at a CFPP (506 MW) used for combined heat and power production in Helsinki, Finland. Fine particle samples (PM 1) were collected after electrostatic precipitator before the desulfurization plant (DSP), including flue gas desulfurization unit (FGD) and baghouse filters, and simultaneously in the smokestack to study the influence of DSP to particulate mass and chemistry. The DSP removed over 97% of particle mass in flue gas. Trace metals were removed efficiently but contribution of some ionic compounds increased in the FGD process. The particle properties were studied in more detail in the smokestack including particle size distribution measurements and size-segregating sampling to study chemical composition and morphology of particles. The particulate emissions from the CFPP were relatively small, consisting mainly of products and reagents of the FGD process (e.g., CaSO 4 , NaCl) and partly of the primary emissions from the coal combustion (e.g., mineral ash and reaction products of gas phase components). The maximum in particle volume was detected at 0.68 mm. PM 1 contributed on average 62 7 5% to PM 10 mass. Besides particulate matter, also the gas-phase emission of mercury was studied because coal combustion is one of the major sources of mercury found in the environment. The mercury emissions were within the proposed limits in the EU.
Unknown host publication, 2011
Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from both ... more Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from both stressed and non-stressed vegetation. In European boreal zone the natural VOC sources are known to surpass the anthropogenic ones. Mechanical stress and damage of plants often strongly increases their monoterpene emissions. As the forests in European boreal zone are under intense economic use, forest management operations can be a significant source of terpenes into the atmosphere of this area. The aim of this study was to estimate the significance of terpene emissions caused by timber felling compared to the emissions from intact forests. We measured the terpenoid emissions from tree stumps and logging residue. The emissions from stumps were studied using enclosures and the emissions from the whole felling area, including stumps and logging residue, using an ecosystem scale micrometeorological method, disjunct eddy accumulation. The compounds analyzed were isoprene, monoterpenes and sesquiterpenes.
Environmental Research Letters, Feb 28, 2022
The Arctic is warming two to three times faster than the global average, and the role of aerosols... more The Arctic is warming two to three times faster than the global average, and the role of aerosols is not well constrained. Aerosol number concentrations can be very low in remote environments, rendering local cloud radiative properties highly sensitive to available aerosol. The composition and sources of the climate-relevant aerosols, affecting Arctic cloud formation and altering their microphysics, remain largely elusive due to a lack of harmonized concurrent multi-component, multi-site, and multi-season observations. Here, we present a dataset on the overall chemical composition and seasonal variability of the Arctic total particulate matter (with a size cut at 10 µm, PM 10 , or without any size cut) at eight observatories representing all Arctic sectors. Our holistic observational approach includes the Russian Arctic, a significant emission source area with less dedicated aerosol monitoring, and extends beyond the more traditionally studied summer period and black carbon/sulfate or fine-mode pollutants. The major airborne Arctic PM components in terms of dry mass are sea salt, secondary (non-sea-salt, nss) sulfate, and organic aerosol (OA), with minor contributions from elemental carbon (EC) and ammonium. We observe substantial spatiotemporal variability in component ratios, such as EC/OA, ammonium/nss-sulfate and OA/nss-sulfate, and fractional contributions to PM. When combined with component-specific back-trajectory analysis to identify marine or terrestrial origins, as well as the companion study by Moschos et al 2022 Nat. Geosci. focusing on OA, the composition analysis provides policy-guiding observational insights into sector-based differences in natural and
Atmospheric Chemistry and Physics, Jun 24, 2016
Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric c... more Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric chemistry. The different physicochemical properties of BVOCs affect their transport within and out of the plant as well as their reactions along the way. Some of these compounds may accumulate in or on the waxy surface layer of conifer needles and participate in chemical reactions on or near the foliage surface. The aim of this work was to determine whether terpenes, a key category of BVOCs produced by trees, can be found on the epicuticles of Scots pine (Pinus sylvestris L.) and, if so, how they compare with the terpenes found in shoot emissions of the same tree. We measured shoot-level emissions of pine seedlings at a remote outdoor location in central Finland and subsequently analysed the needle surface waxes for the same compounds. Both emissions and wax extracts were clearly dominated by monoterpenes, but the proportion of sesquiterpenes was higher in the wax extracts. There were also differences in the terpene spectra of the emissions and the wax extracts. The results, therefore, support the existence of BVOC associated to the epicuticular waxes. We briefly discuss the different pathways for terpenes to reach the needle surfaces and the implications for air chemistry.
Nature Geoscience, Feb 28, 2022
rganic aerosols (OAs) contribute to the Arctic aerosol mass near the surface 1-4 and affect the l... more rganic aerosols (OAs) contribute to the Arctic aerosol mass near the surface 1-4 and affect the local climate through direct aerosol-radiation interactions and by altering the cloud properties 5,6. OAs interact with other aerosol components 7-9 , for example, black carbon or elemental carbon (EC) and sulfate, and can augment or offset their radiative forcing 10. The Arctic OA indirect effect is estimated to be of a similar magnitude as that of the sulfate indirect effect, and much larger than the OA direct effect 11. The magnitude of these effects depends on the OA physicochemical properties, sources and formation processes 12,13 , which are not traceable by satellites 14 , and hence surface observations are indispensable 15. However, OAs have received little attention in the Polar Regions 16-18 , mainly because of measurement challenges, and hence their complex composition and sources are poorly understood 19,20. Nevertheless, an increasing abundance of natural OAs in a warming Arctic is expected 21 as a result of northward-expanding vegetation 22 , intensifying boreal forest fires 23,24 , decreasing sea-ice extent 25 and thawing permafrost 26,27. Enhanced OA emissions are also expected from increasing local anthropogenic emissions, which include oil and gas exploration, and shipping activities 28,29. Attempts to model the Arctic OA concentrations have been limited, with typical under-predictions in winter and/or spring, when haze can be omnipresent and persistent 30-33. The formation of secondary organic aerosols (SOAs) from anthropogenic or natural sources in different seasons is poorly represented 32,34. Of 16 models deployed in a recent AeroCom evaluation of the simulated annual aerosol optical depth in Polar Regions 32 , only 6 considered biogenic precursors, which can contribute to particle growth and so the size range of cloud condensation nuclei. Only in one of the models was methanesulfonic acid (MSA) considered, which resulted in an outlier Arctic aerosol optical depth in terms of both seasonal variability and year-long magnitude 32. A recent study showed that natural
Biogenic acids were measured from PM 2.5 aerosols at SMEAR II station (Station For Measuring Fore... more Biogenic acids were measured from PM 2.5 aerosols at SMEAR II station (Station For Measuring Forest Ecosystem-Atmosphere Relations) in Finland from June 2010 until October 2011. The measured organic acids were pinic, pinonic, caric, limonic and caryophyllinic acids from oxidation of α-pinene, β-pinene, limonene, ∆3-carene and β-caryophyllene. Due to lack of authentic standards caric, limonic and caryophyllinic acids were synthesized at the Laboratory of Organic Chemistry, University of Helsinki. The highest terpenoic acid concentrations were measured during summer concomitant with the precursor mono-and sesquiterpenes. Of the acids β-caryophyllinic acid had highest concentrations in summer, but during other times of the year pinonic acid was the most abundant. The β-caryophyllinic acid contribution was higher than expected on the basis of emission calculations of precursor compounds and yields in oxidation experiments in smog chambers implicating that β-caryophyllene emissions or β-caryophyllinic acid yields are underestimated. Concentration ratios between terpenoic acids and their precursor were clearly lower in summer than in winter indicating stronger partitioning to the aerosol phase during cold winter season. The βcaryophyllinic and caric acids were correlated with the accumulation mode particle number concentrations.
Pan-Arctic surface ozone seasonality modified by sea-ice-sourced bromine: modelling vs measurements
<p>Within the framework of the International Arctic Systems for Observing the Atmosphere (I... more <p>Within the framework of the International Arctic Systems for Observing the Atmosphere (IASOA), we report a modelling-based study on surface ozone across the Arctic. We use surface ozone from six sites: Summit (Greenland), Pallas (Finland), Barrow (USA), Alert (Canada), Tiksi (Russia), and Villum Research Station (VRS) at Station Nord (North Greenland, Danish Realm), and ozonesonde data from three Canadian sites: Resolute, Eureka, and Alert. Two global chemistry models: a global chemistry transport model (p-TOMCAT) and a global chemistry climate model (UKCA), are used for model-data comparisons. Remotely sensed data of BrO from the GOME-2 satellite instrument at Eureka, Canada are used for model validation.</p><p>The observed climatology data show that spring surface ozone at coastal Arctic is heavily depleted, making ozone seasonality at Arctic coastal sites distinctly different from that at inland sites. Model simulations show that surface ozone can be greatly reduced by bromine chemistry. In April, bromine chemistry can cause a net ozone loss (monthly mean) of 10-20 ppbv, with almost half attributable to open-ocean-sourced bromine and the rest to sea-ice-sourced bromine. However, the open-ocean-sourced bromine, via sea spray bromide depletion, cannot by itself produce ozone depletion events (ODEs) (defined as ozone volume mixing ratios VMRs < 10 ppbv). In contrast, sea-ice-sourced bromine, via sea salt aerosol (SSA) production from blowing snow, can produce ODEs even without bromine from sea spray, highlighting the importance of sea ice surface in polar boundary layer chemistry.</p><p>Modelled total inorganic bromine (Br<sub>Y</sub>) over the Arctic sea ice  is sensitive to model configuration, e.g., under the same bromine loading, Br<sub>Y</sub> in the Arctic spring boundary layer in the p-TOMCAT control run (i.e., with all bromine emissions) can be 2 times that in the UKCA control run. Despite the model differences, both model control runs can successfully reproduce large bromine explosion events (BEEs) and ODEs in polar spring. Model-integrated tropospheric column BrO generally matches GOME-2 tropospheric columns within ~50% in UKCA and a factor of 2 in p-TOMCAT. The success of the models in reproducing both ODEs and BEEs in the Arctic indicates that the relevant parameterizations implemented in the models work reasonably well, which supports the proposed mechanism of SSA production and bromide release on sea ice. Given that sea ice is a large source of SSA and halogens, changes in sea ice type and extent in a warming climate will influence Arctic boundary layer chemistry, including the oxidation of atmospheric elemental mercury. Note that this work dose not necessary rule out other possibilities that may act as a source of reactive bromine from sea ice zone.</p>
Shipping and algae emissions have a major impact on ambient air mixing ratios of non-methane hydrocarbons (NMHCs) and methanethiol on Utö Island in the Baltic Sea
Atmospheric chemistry and physics, Apr 19, 2024
Biogeosciences, Apr 10, 2012
Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from vario... more Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from various natural sources. Damaging the plant tissue is known to strongly increase their monoterpene release. We measured the terpenoid emissions caused by timber felling, i.e. those from stumps and logging residue. The emissions from stumps were studied using enclosures and those from the whole felling area using an ecosystem-scale micrometeorological method, disjunct eddy accumulation (DEA). The compounds analyzed were isoprene, monoterpenes and sesquiterpenes. Strong emissions of monoterpenes were measured from both the stumps and from the whole felling area. The emission rate decreased rapidly within a few months after the logging. In addition to fresh logging residue, the results suggest also other strong monoterpene sources may be present in the felling area. These could include pre-existing litter, increased microbial activity and remaining undergrowth. In order to evaluate the possible importance of monoterpenes emitted annually from cut Scots pine forests in Finland, we conducted a rough upscaling calculation. The resulting monoterpene release was approximated to be on the order of 15 kilotonnes per year, which corresponds to about one tenth of the monoterpene release from intact forests in Finland.
Supplement figures S1 and S2 show the monthly variation of BaP and levoglucosan concentrations at... more Supplement figures S1 and S2 show the monthly variation of BaP and levoglucosan concentrations at different stations in 20 Helsinki metropolitan area together with monthly mean temperatures at Kumpula weather station in Helsinki in 2007-2015.
Even though emission inventories indicate that wood combustion is a major source of polycyclic ar... more Even though emission inventories indicate that wood combustion is a major source of polycyclic aromatic hydrocarbons (PAHs), estimating its impacts on PAH concentration in ambient air remains challenging. In this study the effect of local small-scale wood combustion on the benzo[a]pyrene (BaP) concentrations in ambient air in the Helsinki metropolitan area in Finland is evaluated, using ambient air measurements, emission estimates, and dispersion modeling. The measurements were conducted at 12 different locations during the period from 2007 to 2015. The spatial distributions of annual average BaP concentrations originating from wood combustion were predicted for four of those years: 2008, 2011, 2013, and 2014. According to both the measurements and the dispersion modeling, the European Union target value for the annual average BaP concentrations (1 ng m −3) was clearly exceeded in certain suburban detached-house areas. However, in most of the other urban areas, including the center of Helsinki, the concentrations were below the target value. The measured BaP concentrations highly correlated with the measured levoglucosan concentrations in the suburban detached-house areas. In street canyons, the measured concentrations of BaP were at the same level as those in the urban background, clearly lower than those in suburban detached-house areas. The predicted annual average concentrations matched with the measured concentrations fairly well. Both the measurements and the modeling clearly indicated that wood combustion was the main local source of ambient air BaP in the Helsinki metropolitan area.
Atmospheric Chemistry and Physics, Mar 10, 2017
Even though emission inventories indicate that wood combustion is a major source of polycyclic ar... more Even though emission inventories indicate that wood combustion is a major source of polycyclic aromatic hydrocarbons (PAHs), estimating its impacts on PAH concentration in ambient air remains challenging. In this study the effect of local small-scale wood combustion on the benzo[a]pyrene (BaP) concentrations in ambient air in the Helsinki metropolitan area in Finland is evaluated, using ambient air measurements, emission estimates, and dispersion modeling. The measurements were conducted at 12 different locations during the period from 2007 to 2015. The spatial distributions of annual average BaP concentrations originating from wood combustion were predicted for four of those years: 2008, 2011, 2013, and 2014. According to both the measurements and the dispersion modeling, the European Union target value for the annual average BaP concentrations (1 ng m −3) was clearly exceeded in certain suburban detached-house areas. However, in most of the other urban areas, including the center of Helsinki, the concentrations were below the target value. The measured BaP concentrations highly correlated with the measured levoglucosan concentrations in the suburban detached-house areas. In street canyons, the measured concentrations of BaP were at the same level as those in the urban background, clearly lower than those in suburban detached-house areas. The predicted annual average concentrations matched with the measured concentrations fairly well. Both the measurements and the modeling clearly indicated that wood combustion was the main local source of ambient air BaP in the Helsinki metropolitan area.
Assessment of the spatial and temporal distribution of persistent organic pollutants (POPs) in the Nordic atmosphere
Atmospheric Environment, Sep 1, 2016
Atmospheric Environment, Jun 1, 2011
Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambien... more Polycyclic aromatic hydrocarbons (PAH compounds) were measured in the PM 10 fraction [from ambient air] at Virolahti, Finland. The sampling site is located in a rural area in the southeastern corner of Finland, near the Russian border. Altogether, 51 daily and 85 weekly filter samples were collected in 2007e2008. The yearly average concentration of benzo(a)pyrene at Virolahti in 2007 was 0.21 ng m À3 , which is well below the annual target value of 1 ng m À3 set by the European Union. The positive matrix factorization (PMF) method was applied in source apportionment for daily PAH data combined with other pollutant data. A three-factor solution of the PMF analysis with 28 components was chosen. These three factors were identified as long-range transported secondary particles (F1), combustion (F2) and a sea-salt factor (F3). The conditional probability function (CPF) was used to combine wind direction sectors with the PMF factors. In cases F1 and F2, pollutants mainly originated from the southeast , whereas pollutants in F3 came from the southwestern sector. PAHs entered into the combustion factor 2 together with SO 2 , NO x , black carbon and potassium. This suggests that the PAHs at Virolahti originated from traffic and industrial pollution, as well as biomass burning. Elevated concentrations occurred throughout the winter period and most frequently originated from the southeastern sector between 90 e135. This sector includes, among other transboundary areas, the metropolis of St. Petersburg at a distance of 160 km.
Atmospheric aerosols local–regional discrimination for a semi-urban area in India
Atmospheric Research, Feb 1, 2016
Abstract In the European Integrated project on Aerosol Cloud Climate and Air Quality interactions... more Abstract In the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI), measurements were carried out with a sequential filter-based aerosol sampler and on-line instruments for aerosol composition and behaviour at Gual Pahari, close to New Delhi. In fine mode (PM 2.5 ), the secondary organic carbon (SOC) to total organic carbon ratio was 46%. This indicated that condensation of SOC on fine size particles could occur rapidly which may be related to the growth of aerosols and the potential to the size of cloud condensation nuclei in the region. Source region discrimination was improved significantly through coupling conditional probability functions with receptor modelling, and validation through volume size distribution. The air masses from industrial and dense populated regions show a mix of local as well as regional emissions to fine mode aerosols. The back-trajectory analysis captured the long-range transport of sea-salt aerosols enriched with mineral dust. The surface wind directions identified the influence of local emission activities.
Effect of the framework charge density on zeolite ion exchange selectivities
Physical Chemistry Chemical Physics, 2000
The ion exchange selectivity of zeolites has been reassessed by calculations with dielectric theo... more The ion exchange selectivity of zeolites has been reassessed by calculations with dielectric theory. For uni–univalent Na+/K+ and Na+/Rb+ exchanges, the observed selectivities, measured as thermodynamic equilibrium constants, decreased with increasing zeolite aluminium content and charge density. For uni–divalent Na+/Ca2+ and Na+/Sr2+ exchanges, the observed trend was the opposite, the selectivities increased with increasing zeolite charge density. Dielectric theory predicts these trends. Moreover, the quantitative agreement with the theory and observed thermodynamic equilibrium constants is good or fair at low charge densities. This agreement is better than what could be anticipated from previous studies of zeolite selectivities. Dielectric theory clearly fails, however, at higher zeolite charge densities.
Atmospheric Environment, 2018
Journal of Aerosol Science, Jul 1, 2014
Globally more than a quarter of the total primary energy supply is based on coal combustion. The ... more Globally more than a quarter of the total primary energy supply is based on coal combustion. The emissions of coal-fired power plants (CFPPs) are regulated in many industrialized countries and therefore power plants use cleaning techniques to minimize emissions such as sulfur dioxide (SO 2) and particles. In this study, the particulate emissions from coal combustion were investigated at a CFPP (506 MW) used for combined heat and power production in Helsinki, Finland. Fine particle samples (PM 1) were collected after electrostatic precipitator before the desulfurization plant (DSP), including flue gas desulfurization unit (FGD) and baghouse filters, and simultaneously in the smokestack to study the influence of DSP to particulate mass and chemistry. The DSP removed over 97% of particle mass in flue gas. Trace metals were removed efficiently but contribution of some ionic compounds increased in the FGD process. The particle properties were studied in more detail in the smokestack including particle size distribution measurements and size-segregating sampling to study chemical composition and morphology of particles. The particulate emissions from the CFPP were relatively small, consisting mainly of products and reagents of the FGD process (e.g., CaSO 4 , NaCl) and partly of the primary emissions from the coal combustion (e.g., mineral ash and reaction products of gas phase components). The maximum in particle volume was detected at 0.68 mm. PM 1 contributed on average 62 7 5% to PM 10 mass. Besides particulate matter, also the gas-phase emission of mercury was studied because coal combustion is one of the major sources of mercury found in the environment. The mercury emissions were within the proposed limits in the EU.
Unknown host publication, 2011
Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from both ... more Volatile organic compounds (VOCs) including terpenoids are emitted into the atmosphere from both stressed and non-stressed vegetation. In European boreal zone the natural VOC sources are known to surpass the anthropogenic ones. Mechanical stress and damage of plants often strongly increases their monoterpene emissions. As the forests in European boreal zone are under intense economic use, forest management operations can be a significant source of terpenes into the atmosphere of this area. The aim of this study was to estimate the significance of terpene emissions caused by timber felling compared to the emissions from intact forests. We measured the terpenoid emissions from tree stumps and logging residue. The emissions from stumps were studied using enclosures and the emissions from the whole felling area, including stumps and logging residue, using an ecosystem scale micrometeorological method, disjunct eddy accumulation. The compounds analyzed were isoprene, monoterpenes and sesquiterpenes.
Environmental Research Letters, Feb 28, 2022
The Arctic is warming two to three times faster than the global average, and the role of aerosols... more The Arctic is warming two to three times faster than the global average, and the role of aerosols is not well constrained. Aerosol number concentrations can be very low in remote environments, rendering local cloud radiative properties highly sensitive to available aerosol. The composition and sources of the climate-relevant aerosols, affecting Arctic cloud formation and altering their microphysics, remain largely elusive due to a lack of harmonized concurrent multi-component, multi-site, and multi-season observations. Here, we present a dataset on the overall chemical composition and seasonal variability of the Arctic total particulate matter (with a size cut at 10 µm, PM 10 , or without any size cut) at eight observatories representing all Arctic sectors. Our holistic observational approach includes the Russian Arctic, a significant emission source area with less dedicated aerosol monitoring, and extends beyond the more traditionally studied summer period and black carbon/sulfate or fine-mode pollutants. The major airborne Arctic PM components in terms of dry mass are sea salt, secondary (non-sea-salt, nss) sulfate, and organic aerosol (OA), with minor contributions from elemental carbon (EC) and ammonium. We observe substantial spatiotemporal variability in component ratios, such as EC/OA, ammonium/nss-sulfate and OA/nss-sulfate, and fractional contributions to PM. When combined with component-specific back-trajectory analysis to identify marine or terrestrial origins, as well as the companion study by Moschos et al 2022 Nat. Geosci. focusing on OA, the composition analysis provides policy-guiding observational insights into sector-based differences in natural and
Atmospheric Chemistry and Physics, Jun 24, 2016
Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric c... more Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric chemistry. The different physicochemical properties of BVOCs affect their transport within and out of the plant as well as their reactions along the way. Some of these compounds may accumulate in or on the waxy surface layer of conifer needles and participate in chemical reactions on or near the foliage surface. The aim of this work was to determine whether terpenes, a key category of BVOCs produced by trees, can be found on the epicuticles of Scots pine (Pinus sylvestris L.) and, if so, how they compare with the terpenes found in shoot emissions of the same tree. We measured shoot-level emissions of pine seedlings at a remote outdoor location in central Finland and subsequently analysed the needle surface waxes for the same compounds. Both emissions and wax extracts were clearly dominated by monoterpenes, but the proportion of sesquiterpenes was higher in the wax extracts. There were also differences in the terpene spectra of the emissions and the wax extracts. The results, therefore, support the existence of BVOC associated to the epicuticular waxes. We briefly discuss the different pathways for terpenes to reach the needle surfaces and the implications for air chemistry.
Nature Geoscience, Feb 28, 2022
rganic aerosols (OAs) contribute to the Arctic aerosol mass near the surface 1-4 and affect the l... more rganic aerosols (OAs) contribute to the Arctic aerosol mass near the surface 1-4 and affect the local climate through direct aerosol-radiation interactions and by altering the cloud properties 5,6. OAs interact with other aerosol components 7-9 , for example, black carbon or elemental carbon (EC) and sulfate, and can augment or offset their radiative forcing 10. The Arctic OA indirect effect is estimated to be of a similar magnitude as that of the sulfate indirect effect, and much larger than the OA direct effect 11. The magnitude of these effects depends on the OA physicochemical properties, sources and formation processes 12,13 , which are not traceable by satellites 14 , and hence surface observations are indispensable 15. However, OAs have received little attention in the Polar Regions 16-18 , mainly because of measurement challenges, and hence their complex composition and sources are poorly understood 19,20. Nevertheless, an increasing abundance of natural OAs in a warming Arctic is expected 21 as a result of northward-expanding vegetation 22 , intensifying boreal forest fires 23,24 , decreasing sea-ice extent 25 and thawing permafrost 26,27. Enhanced OA emissions are also expected from increasing local anthropogenic emissions, which include oil and gas exploration, and shipping activities 28,29. Attempts to model the Arctic OA concentrations have been limited, with typical under-predictions in winter and/or spring, when haze can be omnipresent and persistent 30-33. The formation of secondary organic aerosols (SOAs) from anthropogenic or natural sources in different seasons is poorly represented 32,34. Of 16 models deployed in a recent AeroCom evaluation of the simulated annual aerosol optical depth in Polar Regions 32 , only 6 considered biogenic precursors, which can contribute to particle growth and so the size range of cloud condensation nuclei. Only in one of the models was methanesulfonic acid (MSA) considered, which resulted in an outlier Arctic aerosol optical depth in terms of both seasonal variability and year-long magnitude 32. A recent study showed that natural
Biogenic acids were measured from PM 2.5 aerosols at SMEAR II station (Station For Measuring Fore... more Biogenic acids were measured from PM 2.5 aerosols at SMEAR II station (Station For Measuring Forest Ecosystem-Atmosphere Relations) in Finland from June 2010 until October 2011. The measured organic acids were pinic, pinonic, caric, limonic and caryophyllinic acids from oxidation of α-pinene, β-pinene, limonene, ∆3-carene and β-caryophyllene. Due to lack of authentic standards caric, limonic and caryophyllinic acids were synthesized at the Laboratory of Organic Chemistry, University of Helsinki. The highest terpenoic acid concentrations were measured during summer concomitant with the precursor mono-and sesquiterpenes. Of the acids β-caryophyllinic acid had highest concentrations in summer, but during other times of the year pinonic acid was the most abundant. The β-caryophyllinic acid contribution was higher than expected on the basis of emission calculations of precursor compounds and yields in oxidation experiments in smog chambers implicating that β-caryophyllene emissions or β-caryophyllinic acid yields are underestimated. Concentration ratios between terpenoic acids and their precursor were clearly lower in summer than in winter indicating stronger partitioning to the aerosol phase during cold winter season. The βcaryophyllinic and caric acids were correlated with the accumulation mode particle number concentrations.
Pan-Arctic surface ozone seasonality modified by sea-ice-sourced bromine: modelling vs measurements
<p>Within the framework of the International Arctic Systems for Observing the Atmosphere (I... more <p>Within the framework of the International Arctic Systems for Observing the Atmosphere (IASOA), we report a modelling-based study on surface ozone across the Arctic. We use surface ozone from six sites: Summit (Greenland), Pallas (Finland), Barrow (USA), Alert (Canada), Tiksi (Russia), and Villum Research Station (VRS) at Station Nord (North Greenland, Danish Realm), and ozonesonde data from three Canadian sites: Resolute, Eureka, and Alert. Two global chemistry models: a global chemistry transport model (p-TOMCAT) and a global chemistry climate model (UKCA), are used for model-data comparisons. Remotely sensed data of BrO from the GOME-2 satellite instrument at Eureka, Canada are used for model validation.</p><p>The observed climatology data show that spring surface ozone at coastal Arctic is heavily depleted, making ozone seasonality at Arctic coastal sites distinctly different from that at inland sites. Model simulations show that surface ozone can be greatly reduced by bromine chemistry. In April, bromine chemistry can cause a net ozone loss (monthly mean) of 10-20 ppbv, with almost half attributable to open-ocean-sourced bromine and the rest to sea-ice-sourced bromine. However, the open-ocean-sourced bromine, via sea spray bromide depletion, cannot by itself produce ozone depletion events (ODEs) (defined as ozone volume mixing ratios VMRs < 10 ppbv). In contrast, sea-ice-sourced bromine, via sea salt aerosol (SSA) production from blowing snow, can produce ODEs even without bromine from sea spray, highlighting the importance of sea ice surface in polar boundary layer chemistry.</p><p>Modelled total inorganic bromine (Br<sub>Y</sub>) over the Arctic sea ice  is sensitive to model configuration, e.g., under the same bromine loading, Br<sub>Y</sub> in the Arctic spring boundary layer in the p-TOMCAT control run (i.e., with all bromine emissions) can be 2 times that in the UKCA control run. Despite the model differences, both model control runs can successfully reproduce large bromine explosion events (BEEs) and ODEs in polar spring. Model-integrated tropospheric column BrO generally matches GOME-2 tropospheric columns within ~50% in UKCA and a factor of 2 in p-TOMCAT. The success of the models in reproducing both ODEs and BEEs in the Arctic indicates that the relevant parameterizations implemented in the models work reasonably well, which supports the proposed mechanism of SSA production and bromide release on sea ice. Given that sea ice is a large source of SSA and halogens, changes in sea ice type and extent in a warming climate will influence Arctic boundary layer chemistry, including the oxidation of atmospheric elemental mercury. Note that this work dose not necessary rule out other possibilities that may act as a source of reactive bromine from sea ice zone.</p>