Hourly trace element measurements were performed in an urban street canyon and next to an interurban freeway in Switzerland during more than one month each, deploying a rotating drum impactor (RDI) ...and subsequent sample analysis by synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). Antimony and other brake wear associated elements were detected in three particle size ranges (2.5−10, 1−2.5, and 0.1−1 μm). The hourly measurements revealed that the effect of resuspended road dust has to be taken into account for the calculation of vehicle emission factors. Individual values for light and heavy duty vehicles were obtained for stop-and-go traffic in the urban street canyon. Mass based brake wear emissions were predominantly found in the coarse particle fraction. For antimony, determined emission factors were 11 ± 7 and 86 ± 42 μg km−1 vehicle−1 for light and heavy duty vehicles, respectively. Antimony emissions along the interurban freeway with free-flowing traffic were significantly lower. Relative patterns for brake wear related elements were very similar for both considered locations. Beside vehicle type specific brake wear emissions, road dust resuspension was found to be a dominant contributor of antimony in the street canyon.
Nonmethane organic gas emissions (NMOGs) from in-service aircraft turbine engines were investigated using a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) at an engine test ...facility at Zurich Airport, Switzerland. Experiments consisted of 60 exhaust samples for seven engine types (used in commercial aviation) from two manufacturers at thrust levels ranging from idle to takeoff. Emission indices (EIs) for more than 200 NMOGs were quantified, and the functional group fractions (including acids, carbonyls, aromatics, and aliphatics) were calculated to characterize the exhaust chemical composition at different engine operation modes. Total NMOG emissions were highest at idling with an average EI of 7.8 g/kg fuel and were a factor of ∼40 lower at takeoff thrust. The relative contribution of pure hydrocarbons (particularly aromatics and aliphatics) of the engine exhaust decreased with increasing thrust while the fraction of oxidized compounds, for example, acids and carbonyls increased. Exhaust chemical composition at idle was also affected by engine technology. Older engines emitted a higher fraction of nonoxidized NMOGs compared to newer ones. Idling conditions dominated ground level organic gas emissions. Based on the EI determined here, we estimate that reducing idle emissions could substantially improve air quality near airports.
The North China Plain (NCP) frequently experiences heavy haze pollution, particularly during wintertime. In winter 2015–2016, the NCP region suffered several extremely severe haze episodes with air ...pollution red alerts issued in many cities. We have investigated the sources and aerosol evolution processes of the severe pollution episodes in Handan, a typical industrialized city in the NCP region, using real-time measurements from an intensive field campaign during the winter of 2015–2016. The average (±1σ) concentration of submicron aerosol (PM1) during 3 December 2015–5 February 2016 was 187.6 (±137.5) µg m−3, with the hourly maximum reaching 700.8 µg m−3. Organic was the most abundant component, on average accounting for 45 % of total PM1 mass, followed by sulfate (15 %), nitrate (14 %), ammonium (12 %), chloride (9 %) and black carbon (BC, 5 %). Positive matrix factorization (PMF) with the multilinear engine (ME-2) algorithm identified four major organic aerosol (OA) sources, including traffic emissions represented by a hydrocarbon-like OA (HOA, 7 % of total OA), industrial and residential burning of coal represented by a coal combustion OA (CCOA, 29 % of total OA), open and domestic combustion of wood and crop residuals represented by a biomass burning OA (BBOA, 25 % of total OA), and formation of secondary OA (SOA) in the atmosphere represented by an oxygenated OA (OOA, 39 % of total OA). Emissions of primary OA (POA), which together accounted for 61 % of total OA and 27 % of PM1, are a major cause of air pollution during the winter. Our analysis further uncovered that primary emissions from coal combustion and biomass burning together with secondary formation of sulfate (mainly from SO2 emitted by coal combustion) are important driving factors for haze evolution. However, the bulk composition of PM1 showed comparatively small variations between less polluted periods (daily PM2. 5 ≤ 75 µg m−3) and severely polluted periods (daily PM2. 5 > 75 µg m−3), indicating relatively synchronous increases of all aerosol species during haze formation. The case study of a severe haze episode, which lasted 8 days starting with a steady buildup of aerosol pollution followed by a persistently high level of PM1 (326.7–700.8 µg m−3), revealed the significant influence of stagnant meteorological conditions which acerbate air pollution in the Handan region. The haze episode ended with a shift of wind which brought in cleaner air masses from the northwest of Handan and gradually reduced PM1 concentration to < 50 µg m−3 after 12 h. Aqueous-phase reactions under higher relative humidity (RH) were found to significantly promote the production of secondary inorganic species (especially sulfate) but showed little influence on SOA.
The formation and evolution of secondary organic aerosol
(SOA) were investigated at Yorkville, GA, in late summer (mid-August to mid-October 2016). The organic aerosol (OA) composition was
measured ...using two online mass spectrometry instruments, the
high-resolution time-of-flight aerosol mass spectrometer (AMS) and the
Filter Inlet for Gases and AEROsols coupled to a high-resolution
time-of-flight iodide-adduct chemical ionization mass spectrometer
(FIGAERO-CIMS). Through analysis of speciated organics data from
FIGAERO-CIMS and factorization analysis of data obtained from both
instruments, we observed notable SOA formation from isoprene and
monoterpenes during both day and night. Specifically, in addition to
isoprene epoxydiol (IEPOX) uptake, we identified isoprene SOA formation from non-IEPOX pathways
and isoprene organic nitrate formation via photooxidation in the presence of
NOx and nitrate radical oxidation. Monoterpenes were found to be the
most important SOA precursors at night. We observed significant
contributions from highly oxidized acid-like compounds to the aged OA factor
from FIGAERO-CIMS. Taken together, our results showed that FIGAERO-CIMS
measurements are highly complementary to the extensively used AMS
factorization analysis, and together they provide more comprehensive
insights into OA sources and composition.
The Sarajevo Canton Winter Field Campaign 2018 (SAFICA) was a project that took place in winter 2017–2018 with an aim to characterize the chemical composition of aerosol in the Sarajevo Canton, ...Bosnia and Herzegovina (BiH), which has one of the worst air qualities in Europe. This paper presents the first characterization of the metals in PM10 (particulate matter aerodynamic diameters ≤10 μm) from continuous filter samples collected during an extended two-months winter period at the urban background Sarajevo and remote Ivan Sedlo sites. We report the results of 18 metals detected by inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS). The average mass concentrations of metals were higher at the Sarajevo site than at Ivan Sedlo and ranged from 0.050 ng/m3 (Co) to 188 ng/m3 (Fe) and from 0.021 ng/m3 (Co) to 61.8 ng/m3 (Fe), respectively. The BenMAP-CE model was used for estimating the annual BiH health (50% decrease in PM2.5 would save 4760+ lives) and economic benefits (costs of $2.29B) of improving the air quality. Additionally, the integrated energy and health assessment with the ExternE model provided an initial estimate of the additional health cost of BiH’s energy system.
The quantification of an aerosol chemical composition is complicated by the uncertainty in the sensitivity of each species detected. Soft-ionization response factors can vary widely from molecule to ...molecule. Here, we have employed a method to separate molecules by their volatility through systematic evaporation with a thermal denuder (TD). The fraction remaining after evaporation is compared between an extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) and a scanning mobility particle sizer (SMPS), which provides a comparison between a quantified mass loss by the SMPS and the signal loss in the EESI-TOF. The sensitivity of the EESI-TOF is determined for both a simplified complex mixture (PEG-300) and also for a complex mixture of α-pinene secondary organic aerosol (SOA). For PEG-300, separation is possible on a molecule-by-molecule level with the TD and provides insights into the molecule-dependent sensitivity of the EESI-TOF, showing a higher sensitivity toward the most volatile molecule. For α-pinene SOA, sensitivity determination for specific classes is possible because of the number of molecular formula observed by the EESI-TOF. These classes are separated by their volatility and are broken down into monomers (O3–5,6–7,8+), dimers (O4–7,8+), and higher order oligomers (e.g., trimers and tetramers). Here, we show that the EESI-TOF initially measures 60.1% monomers, 32.7% dimers, and 7.2% trimers and tetramers in α-pinene SOA, but after sensitivity correction, the distribution of SOA is 37.4% monomers, 56.1% dimers, and 6.4% trimers and tetramers. These results provide a path forward for the quantification of aerosol components with the EESI-TOF in other applications and potentially for atmospheric measurements.
In this study we present measurements of gas and aerosol phase composition for a mixed vehicle fleet in the Gubrist tunnel (Switzerland) in June 2008. PM
1 composition measurements were made with a ...High-Resolution Time-of-Flight Aerosol Mass Spectrometer (AMS) and a Multi Angle Absorption Photometer (MAAP). Gas-phase measurements of CO, CO
2, NO
x and total hydrocarbons (THC) were performed with standard instrumentation. Weekdays had a characteristic diurnal pattern with 2 peaks in concentrations for all traffic related species corresponding to high vehicle density (∼300
±
30 vehicles per 5
min) in the morning rush hour between 06:00 and 09:00 and in the afternoon rush hours from approximately 15:30 to 18:30.
The emission factors (EF) of OA were heavily influenced by the OA mass loading. To exclude this partitioning effect, only organic aerosol mass concentrations from 60
μg
m
−3 to 90
μg
m
−3 were considered and for these conditions the EF(OA) value for HDV was 33.7
±
2.3
mg
km
−1 for a temperature inside the tunnel of 20–25
°C. This value is not directly applicable to ambient conditions because it is derived from OA mass concentrations that are roughly a factor of 10 higher than typical ambient concentrations. An even higher EF(OA)
HDV value of 47.4
±
1.6
mg
km
−1 was obtained when the linear fit was applied to all data points including OA concentrations up to 120
μg
m
−3.
Similar to the increasing EF, the OA/BC ratio in the tunnel was also affected by the organic loading and it increased by a factor of ∼3 over the OA range 10–120
μg
m
−3. This means that also the OA emission factors at ambient concentrations of around 5–10
μg
m
−3 would be 2–3 times lower than the emission factor given above. For OA concentrations lower than 40
μg
m
−3 the OA/BC mass ratio was below 1, while at an OA concentration of 100–120
μg
m
−3 the OA/BC ratio was ∼1.5. The AMS mass spectra (MS) acquired in the tunnel were highly correlated with the primary organic aerosol (POA) MS from a EURO 3 diesel vehicle with a speed similar to the average tunnel speed.
► Measurements of gas and aerosol phase composition in a tunnel are presented. ► PM
1 measurements were made with a HR-ToF-AMS and a MAAP. ► Among the species analyzed, OA and BC were the main constituents of PM
1. ► The emission factors for OA and the OA/BC ratio were affected by the organic mass loading. ► At higher OA concentration more organics in the gas phase will condense producing more OA mass.
Primary biological organic aerosols (PBOA) represent a major component of the coarse organic matter (OMCOARSE, aerodynamic diameter > 2.5 μm). Although this fraction affects human health and the ...climate, its quantification and chemical characterization currently remain elusive. We present the first quantification of the entire PBOACOARSE mass and its main sources by analyzing size-segregated filter samples collected during the summer and winter at the rural site of Payerne (Switzerland), representing a continental Europe background environment. The size-segregated water-soluble OM was analyzed by a newly developed offline aerosol mass spectrometric technique (AMS). Collected spectra were analyzed by three-dimensional positive matrix factorization (3D-PMF), showing that PBOA represented the main OMCOARSE source during summer and its contribution to PM10 was comparable to that of secondary organic aerosol. We found substantial cellulose contributions to OMCOARSE, which in combination with gas chromatography mass spectrometry molecular markers quantification, underlined the predominance of plant debris. Quantitative polymerase chain reaction (qPCR) analysis instead revealed that the sum of bacterial and fungal spores mass represented only a minor OMCOARSE fraction (<0.1%). X-ray photoelectron spectroscopic (XPS) analysis of C and N binding energies throughout the size fractions revealed an organic N increase in the PM10 compared to PM1 consistent with AMS observations.
Isoprene, a compound emitted by vegetation, could be a major contributor to secondary organic aerosols (SOA) in the atmosphere. The main evidence for this contribution were the ...2‐methylbutane‐1,2,3,4‐tetraols, or 2‐methyltetrols (2‐methylerythritol and 2‐methylthreitol) present in ambient aerosols. In this work, the four stereoisomers of these tetraols were analyzed in aerosols from Aspvreten, Sweden. 2‐C‐methyl‐D‐erythritol was found in excess over its enantiomer in the Spring/Summer, by up to 29% in July. This clearly indicated some biological origins for this enantiomer, consistent with its well‐documented production by plants and other living organisms. In addition, a minimum of 20 to 60% of the mass of racemic tetraols appeared from biological origin. Thus, the SOA mass produced by isoprene in the atmosphere is less than what indicated by the 2‐methyltetrols in aerosols. Our results also demonstrate that stereochemical speciation can distinguish primary and secondary organic material in atmospheric aerosols.
Key Points
The first method distinguishing 1ary and 2ary organics in aerosols is proposed
This method shows that the 2‐methyltetrols in some aerosols are biological
The main evidence for isoprene contribution to atmospheric SOA is invalidated
Emissions from the marine transport sector are one of the least-regulated anthropogenic emission sources and contribute significantly to air pollution. Although strict limits were introduced recently ...for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the air quality model CAMx (Comprehensive Air Quality Model with Extensions) with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal concentrations of ozone, primary and secondary components of PM2.5, and the dry and wet deposition of nitrogen and sulfur compounds in Europe. The largest changes in pollutant concentrations due to ship emissions were predicted for summer. Concentrations of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), the English Channel and the North Sea (30–35 %), while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %), where there were high NH3 land-based emissions. Our model results showed that not only are the atmospheric concentrations of pollutants affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships, especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the gas phase to the particle phase which then contributes to an increase in the wet deposition at coastal areas with higher precipitation. In the western Mediterranean region, on the other hand, model results show an increase in the deposition of oxidized nitrogen (mostly HNO3) due to the ship traffic. Dry deposition of SO2 seems to be significant along the shipping routes, whereas sulfate wet deposition occurs mainly along the Scandinavian and Adriatic coasts. The results presented in this paper suggest that evolution of NOx emissions from ships and land-based NH3 emissions will play a significant role in future European air quality.
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