Urban emissions measured with aircraft

Differences between measured and reported volatile organic compound emissions from oil sands facilities in Alberta, Canada

Large-scale oil production from oil sands deposits in Alberta, Canada has raised concerns about environmental impacts, such as the magnitude of air pollution emissions. This paper reports compound emission rates (E) for 69-89 nonbiogenic volatile organic compounds (VOCs) for each of four surface mining facilities, determined with a top-down approach using aircraft measurements in the summer of 2013. The aggregate emission rate (aE) of the nonbiogenic VOCs ranged from 50 ± 14 to 70 ± 22 t/d depending on the facility. In comparison, equivalent VOC emission rates reported to the Canadian National Pollutant Release Inventory (NPRI) using accepted estimation methods were lower than the aE values by factors of 2.0 ± 0.6, 3.1 ± 1.1, 4.5 ± 1.5, and 4.1 ± 1.6 for the four facilities, indicating underestimation in the reported VOC emissions. For 11 of the combined 93 VOC species reported by all four facilities, the reported emission rate and E were similar; but for the other 82 species, the reported emission rate was lower than E The median ratio of E to that reported for all species by a facility ranged from 4.5 to 375 depending on the facility. Moreover, between 9 and 53 VOCs, for which there are existing reporting requirements to the NPRI, were not included in the facility emission reports. The comparisons between the emission reports and measurement-based emission rates indicate that improvements to VOC emission estimation methods would enhance the accuracy and completeness of emission estimates and their applicability to environmental impact assessments of oil sands developments.

Predicting photochemical pollution in an industrial area

In order to confront pollution events concerning the city of Elefsis, in the environmentally aggravated area of Thriassion Plain, an effort is undertaken to create a model forecasting maximal daily concentrations of NO(x) (NO(2)+NO), NO(2) and O(3). The data analyzed were obtained from the Bureau of Pollution Control and Environments Quality based in Elefsis. The model in question uses hourly values of the pollutants as well as meteorological data recorded at the center of the city of Elefsis from 1993 to 1999. Three fitting methods are utilized, namely ordinary least squares, piecewise, and quantile regression. The verification and reliability of the forecasting models are based on the measurements of the year 2000. The results are considered to be satisfactory, with the forecasted values following the general tendencies.

Characterization of urban pollutant emission fluxes and ambient concentration distributions using a mobile laboratory with rapid response instrumentation

A large and increasing fraction of the planet's population lives in megacities, especially in the developing world. These large metropolitan areas generally have very high levels of both gaseous and particulate air pollutants that have severe impacts on human health, ecosystem viability, and climate on local, regional, and even continental scales. Emissions fluxes and ambient pollutant concentration distributions are generally poorly characterized for large urban areas even in developed nations. Much less is known about pollutant sources and concentration patterns in the faster growing megacities of the developing world. New methods of locating and measuring pollutant emission sources and tracking subsequent atmospheric chemical transformations and distributions are required. Measurement modes utilizing an innovative van based mobile laboratory equipped with a suite of fast response instruments to characterize the complex and "nastier" chemistry of the urban boundary layer are described. Instrumentation and measurement strategies are illustrated with examples from the Mexico City and Boston metropolitan areas. It is shown that fleet average exhaust emission ratios of formaldehyde (HCHO), acetaldehyde (CH3CHO) and benzene (C6H6) are substantial in Mexico City, with gasoline powered vehicles emitting higher levels normalized by fuel consumption. NH3 exhaust emissions from newer light duty vehicles in Mexico City exceed levels from similar traffic in Boston. A mobile conditional sampling air sample collection mode designed to collect samples from intercepted emission plumes for later analysis is also described.

Mobile laboratory with rapid response instruments for real-time measurements of urban and regional trace gas and particulate distributions and emission source characteristics

Recent technological advances have allowed the development of robust, relatively compact, low power, rapid response (approximately 1 s) instruments with sufficient sensitivity and specificity to quantify many trace gases and aerosol particle components in the ambient atmosphere. Suites of such instruments can be deployed on mobile platforms to study atmospheric processes, map concentration distributions of atmospheric pollutants, and determine the composition and intensities of emission sources. A mobile laboratory containing innovative tunable infrared laser differential absorption spectroscopy (TILDAS) instruments to measure selected trace gas concentrations at sub parts-per-billion levels and an aerosol mass spectrometer (AMS) to measure size resolved distributions of the nonrefractory chemical components of fine airborne particles as well as selected commercial fast response instruments and position/velocity sensors is described. Examples of the range of measurement strategies that can be undertaken using this mobile laboratory are discussed, and samples of measurement data are presented.

Volatile hydrocarbons in the atmosphere of Athens, Greece

This work presents the results of one-year monitoring study of Volatile Hydrocarbons, VHCs, in the atmosphere of Athens. It is the first systematic attempt to determine the VHC levels in the Athens' atmosphere with the very well known photochemical pollution problems. The purpose of this work was to create a database concerning VHCs in order to evaluate the photochemical pollution in this area (ozone creation, case studies and meteorology). Totally, 308 samples were collected at three different sites used in the state-monitoring programme involving the criteria pollutants. Air samples were collected on Tenax TA tubes and analysed by thermal desorption and dual column GC dual FID. Fifteen selected compounds were studied; 6 alkanes and 9 benzenoid compounds. The measured values of individual alkanes ranged from 0.39 pg m(-3) to 33 pg m(-3), and those of aromatics from 0.20 pg m(-3) to 616 pg m(-3). The sum of all 15 VHC concentrations ranged between 16 and 1697 pg m(-3). The time and spatial variations in the concentration of these compounds were assessed. Volatile hydrocarbons exhibited a clear seasonal and time cycle, showing higher concentrations during winter and early morning hours. Study of the spatial variations of VHC levels showed higher concentrations at the center of the city. The variation of toluene/benzene ratio and the correlation between VHCs, criteria pollutants (CO, NOx and O3) and meteorological parameters were also assessed. It was demonstrated that a trip-line of the VHCs concentration at the city center doubles the ozone concentration at peripheral areas under favourable meteorological conditions.

C3 to C9 hydrocarbon measurements in the two largest cities of Greece, Athens and Thessaloniki. Calculation of hydrocarbon emissions by species. Derivation of hydroxyl radical concentrations

Non-methane hydrocarbon concentrations (NMHC) were determined in samples collected in electropolished canisters aboard a Falcon aircraft in Athens and Thessaloniki. Some canisters were also collected on the ground in Athens. Chemical analysis by cryoconcentration permitted the speciation of NMHC. The aircraft samples allowed the determination of the background concentrations in the periphery of each city. Concentration ratios were compared with other European cities. The aromatic hydrocarbon fraction dominates the measured species. Using the simple box model modified to account for the chemical destruction of each hydrocarbon, the emissions for each species were determined in Athens and Thessaloniki. The hydroxyl radical concentrations were calculated using hydrocarbon concentration ratios in the urban areas and at a downwind distance.