Real-time measurements of submicrometer aerosol were performed using an Aerodyne aerosol mass spectrometer (AMS) during three weeks at an urban background site in Zurich (Switzerland) in January ...2006. A hybrid receptor model which incorporates a priori known source composition was applied to the AMS highly time-resolved organic aerosol mass spectra. Three sources and components of submicrometer organic aerosols were identified: the major component was oxygenated organic aerosol (OOA), mostly representing secondary organic aerosol and accounting on average for 52–57% of the particulate organic mass. Radiocarbon (14C) measurements of organic carbon (OC) indicated that ∼31 and ∼69% of OOA originated from fossil and nonfossil sources, respectively. OOA estimates were strongly correlated with measured particulate ammonium. Particles from wood combustion (35–40%) and 3–13% traffic-related hydrocarbon-like organic aerosol (HOA) accounted for the other half of measured organic matter (OM). Emission ratios of modeled HOA to measured nitrogen oxides (NO x ) and OM from wood burning to levoglucosan from filter analyses were found to be consistent with literature values.
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.
Twenty-one oxygenated volatile organic compounds (OVOCs) were measured in four seasonal campaigns at an urban background site in Zürich (Switzerland) with a newly developed double adsorbent sampling ...unit coupled to a gas chromatograph–mass spectrometer (GC–MS). In addition, selected non-methane hydrocarbons (NMHCs) were measured, as well as formaldehyde in the summer and winter campaign. The most abundant compound measured in all seasons was ethanol, with peak values of more than 60
ppb. Its seasonal variation with a lower mean value in summer compared to that in winter implied mostly anthropogenic sources. In contrast, compounds with additional biogenic sources, or compounds known to be produced in the troposphere by oxidation processes, had seasonal maxima in summer (e.g. methanol, acetone, formaldehyde, methacrolein and 2-butenone (methyl vinyl ketone, MVK)).
For the OVOCs it was estimated that local sources contributed 40% and 49% to the mixing ratios of the measured compounds in summer and in winter, respectively. Combustion was estimated to contribute 75% to these local sources independent of the season. About 50% of both the OVOC and NMHC levels in Zürich could be explained by the regional background, which included regional biogenic and anthropogenic sources in addition to secondary production. Industrial sources were identified for acetone, butanone (methyl ethyl ketone, MEK),
n-propanol, iso-propanol,
n-butanol, ethyl acetate and butyl acetate.
Long-term observations of reactive gases in the troposphere are important for understanding trace gas cycles and the oxidation capacity of the atmosphere, assessing impacts of emission changes, ...verifying numerical model simulations, and quantifying the interactions between short-lived compounds and climate change. The World Meteorological Organization’s (WMO) Global Atmosphere Watch (GAW) program coordinates a global network of surface stations some of which have measured reactive gases for more than 40 years. Gas species included under this umbrella are ozone, carbon monoxide, nitrogen oxides, and volatile organic compounds (VOCs). There are many challenges involved in setting-up and maintaining such a network over many decades and to ensure that data are of high quality, regularly updated and made easily accessible to users. This overview describes the GAW surface station network of reactive gases, its unique quality management framework, and discusses the data that are available from the central archive. Highlights of data use from the published literature are reviewed, and a brief outlook into the future of GAW is given. This manuscript constitutes the overview of a special feature on GAW reactive gases observations with individual papers reporting on research and data analysis of particular substances being covered by the program.
The Global Atmosphere Watch (GAW) program currently coordinates 22 ground‐based atmospheric background monitoring stations of global scope. The GAW World Calibration Centre for Surface Ozone, Carbon ...Monoxide and Methane (WCC‐EMPA) is responsible for tracing surface ozone measurements at these stations to the designated reference within the GAW program, the Standard Reference Photometer SRP 2 maintained at the National Institute of Standards and Technology (NIST). The recommended method for surface ozone measurements is based on UV absorption at 254 nm (Hg line). Repeated and regular intercomparisons of station instruments are necessary to achieve and maintain high and known data quality. In this paper, the traceability chain is explained, and standard uncertainties for each element are evaluated. Data of 26 intercomparisons performed at 14 stations between 1996 and 2002 are analyzed. On 23 occasions, the instruments passed the audit with “good” agreement, in one case with “sufficient” agreement. On 2 occasions, both first audits at the site, the audited instrument did not comply with the minimal data quality requirements. The best instruments in use exhibit a median absolute bias of approximately 0.32 ppbv and a standard uncertainty of approximately 0.8 ppbv (0–100 ppbv). The quantitative improvement of data quality as a result of repeated audits can be demonstrated with several stations.
At the high Alpine site of Jungfraujoch (3580 m asl), 23 halogenated greenhouse gases are measured quasi‐continuously by gas chromatography‐mass spectrometry (GCMS). Measurement data from the years ...2000–2002 are analyzed for trends and pollution events. Concentrations of the halogenated trace gases, which are already controlled in industrialized countries by the Montreal Protocol (e.g., CFCs) were at least stable or declining. Positive trends in the background concentrations were observed for substances which are used as CFC‐substitutes (hydrofluorocarbons, hydrochlorofluorocarbons). Background concentrations of the hydrofluorocarbons at the Jungfraujoch increased from January 2000 until December 2002 as follows: HFC 134a (CF3CH2F) from 15 to 27 ppt, HFC 125 (CF3CHF2) from 1.4 to 2.8 ppt, and HFC 152a (CHF2CH3) from 2.3 to 3.2 ppt. For HFC 152a, a distinct increase of its concentration magnitude during pollution events was observed from 2000 to 2002, indicating rising European emissions for this compound. Background concentrations of all measured compounds were in good agreement with similar measurements at Mace Head, Ireland. On the other hand, peak concentrations were significantly higher at the Jungfraujoch. This finding is due to the proximity to potent European sources, foremost in southern Europe. The average ratio of halocarbons versus carbon monoxide (CO) concentrations above their baseline values was used to estimate source strengths for the part of Europe which most influences the Jungfraujoch during pollution events. HFCs emission estimates from Jungfraujoch tend to be higher than figures at Mace Head (Ireland) from the end of the 1990s, which either reflects the increased use of these compounds or the closer location of Jungfraujoch to major southern European sources. Transport of polluted European boundary layer air masses to the high Alpine site was observed especially during frontal passages, foehn events, and thermal lifting of air masses in summer. The measurement data during the periods when the Jungfraujoch was under the influence of the polluted boundary layer were used in combination with concurrent air mass trajectories to allocate above baseline halocarbon concentrations to specific European source regions.
How does global warming drive emissions of carbon dioxide, methane, and nitrous oxide from natural ecosystems such as peat- and wetlands? Target species are carbon dioxide and other greenhouse gases, ...stable isotopes, and radiocarbon in greenhouse gas measurements. ...GGMT serves as the scientific backbone of the observation programs of the WMO, supporting worldwide compatibility of observations relevant for scientists, policymakers, and international treaties. The ICDC10 organizers thank the following institutions for sponsorship: the Intergovernmental Panel on Climate Change (IPCC), the World Climate Research Programme (WCRP), Future Earth, the Global Carbon Project (GCP), the Global Land Project (GLP), the High Altitude Research Stations Jungfraujoch & Gornergrat (HFSJG), the Integrated Marine Biogeochemistry and Ecosystem Research (IMBER), the International Ocean Carbon Coordination Project (IOCCP), the International Space Science Institute (ISSI), the Ocean Acidification International Coordination Centre/International Atomic Energy Agency (OA_ICC, IAEA), Past Global Changes (PAGES), the Forum for Climate and Global Change of the Swiss Academy of Sciences (ProCLIM), and the Surface Ocean Lower Atmosphere Study (SOLAS).
Collocated parallel measurements of PM2.5 and PM10 were conducted at 7 sites in Switzerland since January 1998, constituting now one of the longest comparative data sets for PM2.5 and PM10 in Europe. ...The range of the long-term mean concentrations of PM2.5 was between 7.9
μg/m
3 at Chaumont and 24.4
μg/m
3 in Lugano. For the sites within the Swiss plateau this range narrows from 15.1
μg/m
3 at the rural site of Payerne to 20.8
μg/m
3 at the directly traffic exposed site of Bern. The long-term averages of the PM2.5/PM10 ratios of the daily values vary only from 0.75 to 0.76, with the exception of the traffic exposed site of Bern (0.59). The correlation between the daily values of PM2.5 and PM10 at all sites is generally high. For PM10, as well as for PM2.5 the highest concentrations are normally observed during wintertime. An exception is Chaumont (1140-m a.s.l.), which is often positioned above the inversion layer during wintertime and, therefore, has the lowest concentration during wintertime. A minimum of the PM2.5/PM10 ratio is often found during spring, probably due to the influence of relatively coarse biogenic particles. Though the sites have quite different exposition characteristics, the correlation of the daily values of PM2.5 and PM10 between the different sites of the Swiss plateau is very high, indicating a dominant influence of regional meteorology over local events and sources. The findings imply that from the point of view of an efficient use of financial and personal resources, the number of collocated PM2.5 measurements at PM10 sites in a monitoring network can be kept quite limited. The saved resources could rather be used to investigate other particle related parameters providing substantial new information (e.g. on particle sources, formation and effects) like PM1, particle number concentrations, morphology or chemical composition.
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