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Atmospheric Environment (v.43, #8)
Secondary organic aerosol production from aqueous photooxidation of glycolaldehyde: Laboratory experiments by Mark J. Perri; Sybil Seitzinger; Barbara J. Turpin (pp. 1487-1497).
Organic particulate matter (PM) formed in the atmosphere (secondary organic aerosol; SOA) is a substantial yet poorly understood contributor to atmospheric PM. Aqueous photooxidation in clouds, fogs and aerosols is a newly recognized SOA formation pathway. This study investigates the potential for aqueous glycolaldehyde oxidation to produce low volatility products that contribute SOA mass. To our knowledge, this is the first confirmation that aqueous oxidation of glycolaldehyde via the hydroxyl radical forms glyoxal and glycolic acid, as previously assumed. Subsequent reactions form formic acid, glyoxylic acid, and oxalic acid as expected. Unexpected products include malonic acid, succinic acid, and higher molecular weight compounds, including oligomers. Due to (1) the large source strength of glycolaldehyde from precursors such as isoprene and ethene, (2) its water solubility, and (3) the aqueous formation of low volatility products (organic acids and oligomers), we predict that aqueous photooxidation of glycolaldehyde and other aldehydes in cloud, fog, and aerosol water is an important source of SOA and that incorporation of this SOA formation pathway in chemical transport models will help explain the current under-prediction of organic PM concentrations.
Keywords: Secondary organic aerosol; Cloud processing; Glycolaldehyde; Oligomer; Particulate matter; Oxalic acid; Glycolic acid; Malonic acid; Succinic acid; Electrospray ionization mass spectrometry; Fourier transform ion cyclotron resonance mass spectrometry; Isoprene
Ground-based measurements and modeling of solar UV-B radiation in Lhasa, Tibet by Gelsor Norsang; Ladislav Kocbach; Wangmu Tsoja; Jakob J. Stamnes; Arne Dahlback; Pingcuo Nema (pp. 1498-1502).
We present results from measurements by a NILU-UV Irradiance Meter of solar UV-B radiation in Lhasa, Tibet for the period from 7 July 1999 to 17 November 2002. The measured maximum UV-B dose rate was 1.50W/m2 during the winter, and 3.96W/m2, during the summer. The clear-sky values were below 3.00W/m2. Comparisons between measured and calculated UV-B dose rates on clear-sky days in Lhasa show good agreement. Comparisons of UV-B radiation levels in Lhasa (Tibet), Oslo (Norway), and Dar-Es-Salaam (Tanzania) show that the UV-B dose rates during the summer in Lhasa are higher than the maximum value in Dar-Es-Salaam, which is at the sea level in the equatorial region, and 60% higher than in Oslo, which is at the sea level but 60 degrees North. We conclude that the UV-B dose rates during the summer on the Tibetan plateau are among the highest levels in habituated regions of the world. Maximum measured daily-integrated UV-B doses in Lhasa range from about 10kJ/m2 in the winter to about 65kJ/m2 in the summer.
Keywords: UV-B; NILU-UV Irradiance Meter; Radiative transfer model; Clear day
Assessing the real-world performance of modern pollutant abatement systems on motorcycles by Robert Alvarez; Martin Weilenmann; Jean-Yves Favez (pp. 1503-1509).
The present statutory pollutant emission limits Euro-3 for motorcycles imply the use of modern emission abatement systems such as three-way catalytic converters. Determining the quality of implementation of these new systems in different driving situations such as real-world driving is important, since motorcycles are commonly used for personal transportation in urban areas. For this reason, a test bench series was carried out with a sample of 10 motorcycles of state-of-the-art certification category Euro-3. Emission factors of regulated pollutants and CO2 are presented on the basis of the statutory driving cycle, the latest version of the real-world Worldwide Motorcycle Test Cycle (WMTC) and the real-world Common Artemis Driving Cycle (CADC).The results of the statutory driving cycle show that 7 out of 10 motorcycles fail to comply with the present emission limits. The results of both real-world driving cycles confirm notable emissions of HC in urban and NO x in motorway driving conditions. CO emissions of motorcycles with small displacement increase significantly in the urban and extra-urban sections of the CADC, which has a more dynamic velocity profile than the equivalent WMTC. Although pollutant emissions of motorcycles show a marked improvement compared with earlier certification classes, they clearly exceed the emission levels of modern light gasoline passenger cars, especially for CO and HC.
Keywords: Motorcycle; Pollutant; Emission; Real-world
Assessing the impacts of current and future concentrations of surface ozone on crop yield with meta-analysis by Zhaozhong Feng; Kazuhiko Kobayashi (pp. 1510-1519).
Meta-analysis was conducted to quantitatively assess the effects of rising ozone concentrations ([O3]) on yield and yield components of major food crops: potato, barley, wheat, rice, bean and soybean in 406 experimental observations. Yield loss of the crops under current and future [O3] was expressed relative to the yield under base [O3] (≤26ppb). With potato, current [O3] (31–50ppb) reduced the yield by 5.3%, and it reduced the yield of barley, wheat and rice by 8.9%, 9.7% and 17.5%, respectively. In bean and soybean, the yield losses were 19.0% and 7.7%, respectively. Compared with yield loss at current [O3], future [O3] (51–75ppb) drove a further 10% loss in yield of soybean, wheat and rice, and 20% loss in bean. Mass of individual grain, seed, or tuber was often the major cause of the yield loss at current and future [O3], whereas other yield components also contributed to the yield loss in some cases. No significant difference was found between the responses in crops grown in pots and those in the ground for any yield parameters. The ameliorating effect of elevated [CO2] was significant in the yields of wheat and potato, and the individual grain weight in wheat exposed to future [O3]. These findings confirm the rising [O3] as a threat to food security for the growing global population in this century.
Keywords: Ozone; Wheat; Rice; Soybean; Potato; Barley; Bean
The effect of EURO-0 vehicle substitution on polycyclic aromatic hydrocarbon and carbon monoxide concentrations in an urban area by Federico Valerio; Anna Stella; Mauro Pala; Daniele Balducci; Maria Teresa Piccardo; Massimo Cipolla (pp. 1520-1526).
From 1994 to 2003, daily air concentrations of particle-bound polycyclic aromatic hydrocarbons (PAHs) and carbon monoxide (CO) were regularly monitored at two traffic-oriented sampling sites (A and B) in urban Genoa, Italy. The data were used to estimate effects on air quality in real situations due to progressive substitution of EURO-0 vehicles, started in 1993, with less-polluting vehicles (EURO-1, EURO-2), mainly gasoline vehicles with a catalyst. PAH profile classification and diagnostic PAH ratios were used to identify 345 samples of predominantly traffic origin. At both sites, CO and PAH daily concentrations decreased exponentially with time and the apparent half-life values calculated were 6.3 and 5.5 for CO and 3.7 and 3.5 years for PAHs at sites A and B, respectively. At site A, monitored for traffic intensity, multiple regression analyses confirmed that daily PAH and CO concentrations were positively correlated with the number of non-catalytic vehicles estimated to cross this site during sampling and negatively correlated with seasonal variables (air temperature, ozone concentration, relative air humidity). The reduction in air pollution estimated for complete substitution of non-catalytic gasoline vehicles was 89% for BaP, 85% for total PAHs and 69% for CO.
Keywords: Air pollution; Temporal trend; Emission sources; Catalytic converter; Urban traffic
Polyfluorinated compounds in ambient air from ship- and land-based measurements in northern Germany by Annekatrin Dreyer; Ralf Ebinghaus (pp. 1527-1535).
Neutral volatile and semi-volatile polyfluorinated organic compounds (PFC) and ionic perfluorinated compounds were determined in air samples collected at two sites in the vicinity of Hamburg, Germany, and onboard the German research vessel Atair during a cruise in the German Bight, North Sea, in early November 2007. PUF/XAD-2/PUF cartridges and glass fiber filters as sampling media were applied to collect several fluorotelomer alcohols (FTOH), fluorotelomer acrylates (FTA), perfluoroalkyl sulfonamides (FASA), and perfluoroalkyl sulfonamido ethanols (FASE) in the gas- and particle-phase as well as a set of perfluorinated carboxylates (PFCA) and sulfonates (PFSA) in the particle-phase. This study presents the distribution of PFC in ambient air of the German North Sea and in the vicinity of Hamburg for the first time. Average total PFC concentrations in and around Hamburg (180pg m−3) were higher than those observed in the German Bight (80pg m−3). In the German Bight, minimum–maximum gas-phase concentrations of 17–82pg m−3 for ΣFTOH, 2.6–10pg m−3 for ΣFTA, 10–15pg m−3 for ΣFASA, and 2–4.4pg m−3 for ΣFASE were determined. In the vicinity of Hamburg, minimum–maximum gas-phase concentrations of 32–204pg m−3 for ΣFTOH, 3–26pg m−3 for ΣFTA, 3–18pg m−3 for ΣFASA, and 2–15pg m−3 for ΣFASE were detected. Concentrations of perfluorinated acids were in the range of 1–11pg m−3. FTOH clearly dominated the substance spectrum; 8:2 FTOH occurred in maximum proportions. Air mass back trajectories, cluster, and correlation analyses revealed that the air mass origin and thus medium to long range atmospheric transport was the governing parameter for the amount of PFC in ambient air. Southwesterly located source regions seemed to be responsible for elevated PFC concentrations, local sources appeared to be of minor importance.
Keywords: PFC; Atmospheric transport; North Sea; Hamburg; Fluorotelomer alcohols; FTOH; Perfluorosulfon amides; PFCA
European222Rn inventory for applied atmospheric studies by T. Szegvary; F. Conen; P. Ciais (pp. 1536-1539).
The radioactive noble gas222Rn, naturally emitted from land surfaces, is widely used as a tracer in characterising atmospheric transport and mixing processes. A constant and homogenous222Rn source of 1atomcm−2s−1 is generally assumed, sometimes less in northern latitudes. It is well known that222Rn flux varies in space and time but a robust description of it on a continental scale has not been possible before. Here, we present for the first time a spatially and temporally resolved222Rn source map for the European Continent (European Union, Norway, former Yugoslavia and Switzerland). It is based on the correlation between the222Rn flux and terrestrial γ-dose rate. Total γ-dose rate is monitored in this area at nearly 3600 stations continuously and the terrestrial component can be extracted from these measurements. On a resulting 0.5°×0.5° map, mean annual values of222Rn flux ranged from 0.03 to 1.76atomcm−2s−1, half of the values being between 0.40 and 0.70atomcm−2s−1. The source strength was patchy but exhibited a decreasing trend with increasing latitude. Large values were mainly found on the Iberian Peninsula, small values along coasts and in northern and eastern parts of Europe. The seasonal amplitude in222Rn flux south of 55°N was small in 2006 with weekly averages deviating less than ±15% from the annual mean. Between 65°N and 70°N, weekly means are 2.5 times larger in summer than in winter.
Keywords: Radon flux; Atmospheric transport; Climate modelling; Tracer
Satellite observations of Mexico City pollution outflow from the Tropospheric Emissions Spectrometer (TES) by Changsub Shim; Qinbin Li; Ming Luo; Susan Kulawik; Helen Worden; John Worden; Annmarie Eldering; Glenn Diskin; Glen Sachse; Andy Weinheimer; David Knapp; Deedee Montzca; Teresa Campos (pp. 1540-1547).
Concurrent tropospheric O3 and CO vertical profiles from the Tropospheric Emission Spectrometer (TES) during the MILAGRO/INTEX-B aircraft campaigns over the Mexico City Metropolitan Area (MCMA) and its surrounding regions were used to examine Mexico City pollution outflow on a regional scale. The pollution outflow from the MCMA occurred predominantly at 600–800hPa as evident in O3, CO, and NO x enhancements in the in situ aircraft observations. TES O3 and CO are sensitive to the MCMA pollution outflow due to their relatively high sensitivities at 600–800hPa. We examined O3, CO, and their correlation at 600–800hPa from TES retrievals, aircraft measurements, and GEOS-Chem model results. TES captures much of the spatial and day-to-day variability of O3 seen in the in situ data. TES CO, however, shows much less spatial and day-to-day variability compared with the in situ observations. The ΔO3/ΔCO slope is significantly higher in the TES data (0.43) than the in situ data (0.28) due partly to the lack of variability in TES CO. Extraordinarily high ΔO3/ΔCO slope (0.81) from TES observations at 618hPa over the Eastern U.S. was previously reported by Zhang et al. [Zhang, L., Jacob, D.J., Bowman, K.W., et al., 2006. Ozone–CO correlations determined by the TES satellite instrument in continental outflow regions. Geophys. Res. Lett. 33, L18804. 10.1029/2006GL026399.]. Thus the application of TES CO–O3 correlation to map continental pollution outflow needs further examination.
Keywords: Keyword; Mega-city pollution; TES; O; 3; –CO correlation; INTEX-B; Mexico city
Definition of yearly emission factor of dust and greenhouse gases through continuous measurements in swine husbandry by Annamaria Costa; Marcella Guarino (pp. 1548-1556).
The object of this study was to develop an accurate estimation method to evaluate the contribution of the various compartments of swine husbandry to dust and GHG (greenhouse gases, CO2, CH4 and N2O) emission into the atmosphere during one year of observation.A weaning, a gestation, a farrowing and a fattening room in an intensive pig house were observed in three different periods (Autumn–Winter, Springtime and Summer, monitoring at least 60% of each period (20% at the beginning, in the middle and at the end) of each cycle).During monitoring, live weight, average live weight gain, number of animals and its variation, type of feed and feeding time were taken into account to evaluate their influence on PM10, or the fraction of suspended particulate matter with an aerodynamic diameter less than or equal to 10μm [Emission Inventory Guidebook, 2007. B1100 Particle Emissions from Animal Husbandry Activities. Available from: (accessed October 2008)] and to define GHG emission.The selected piggery had a ventilation control system using a free running impeller to monitor continuously real-time environmental and management parameters with an accuracy of 5%.PM10 concentration was monitored by a sampler (Haz Dust EPAM 5000), either continuously or through traditional gravimetric technique, and the mean value of dust amount collected on the membranes was utilized as a correction factor to be applied to continuously collected data.PM10 concentration amount incoming from inlets was removed from PM10 emission calculation, to estimate the real contribution of pig house dust pollution into atmosphere.Mean yearly emission factor of PM10 was measured in 2gd−1LU−1 for the weaning room, 0.09gd−1LU−1 for the farrowing room, 2.59gd−1LU−1 for the fattening room and 1.23gd−1LU−1 for the gestation room. The highest PM10 concentration and emission per LU was recorded in the fattening compartment while the lowest value was recorded in the farrowing room.CO2, CH4 and N2O concentrations were continuously measured in the exhaust ducts using an infrared photoacoustic detector IPD (Brüel & Kjaer, Multi-gas Monitor Type 1302, Multipoint Sampler and Doser Type 1303) sampling data every 15min, for the 60% of the cycles.Yearly emission factor for CO2 was measured in 5997gd−1LU−1 for the weaning room, 1278gd−1LU−1 for the farrowing room, 13,636gd−1LU−1 for the fattening room and 8851gd−1LU−1 for the gestation room.Yearly emission factor for CH4 was measured in 24.57gd−1LU−1 for the weaning room, 4.68gd−1LU−1 for the farrowing room, 189.82gd−1LU−1 for the fattening room and 132.12gd−1LU−1 for the gestation room.Yearly emission factor for N2O was measured in 3.62gd−1LU−1 for the weaning room, 0.66gd−1LU−1 for the farrowing room, 3.26gd−1LU−1 for the fattening room and 2.72gd−1LU−1 for the gestation room.
Keywords: Dust; Greenhouse gases; Concentration; Emission; Mechanical Ventilation; Swine houses
Computation of uncertainty for atmospheric emission projections from key pollutant sources in Spain by Julio Lumbreras; Carolina García-Martos; José Mira; Rafael Borge (pp. 1557-1564).
Emission projections are important for environmental policy, both to evaluate the effectiveness of abatement strategies and to determine legislation compliance in the future. Moreover, including uncertainty is an essential added value for decision makers. In this work, projection values and their associated uncertainty are computed for pollutant emissions corresponding to the most significant activities from the national atmospheric emission inventory in Spain. Till now, projections had been calculated under three main scenarios: “without measures” (WoM), “with measures” (WM) and “with additional measures” (WAM). For the first one, regression techniques had been applied, which are inadequate for time-dependent data. For the other scenarios, values had been computed taking into account expected activity growth, as well as policies and measures. However, only point forecasts had been computed. In this work statistical methodology has been applied for: a) Inclusion of projection intervals for future time points, where the width of the intervals is a measure of uncertainty. b) For the WoM scenario, ARIMA models are applied to model the dynamics of the processes. c) In the WM scenario, bootstrap is applied as an additional non-parametric tool, which does not rely on distributional assumptions and is thus more general. The advantages of using ARIMA models for the WoM scenario including uncertainty are shown. Moreover, presenting the WM scenario allows observing if projected emission values fall within the intervals, thus showing if the measures to be taken to reach the scenario imply a significant improvement. Results also show how bootstrap techniques incorporate stochastic modelling to produce forecast intervals for the WM scenario.
Keywords: Emission projections; Uncertainty; Time series analysis; ARIMA models; Bootstrap
Trends in on-road vehicle emissions of ammonia by A.J. Kean; D. Littlejohn; G.A. Ban-Weiss; R.A. Harley; T.W. Kirchstetter; M.M. Lunden (pp. 1565-1570).
Motor vehicle emissions of ammonia have been measured at a California highway tunnel in the San Francisco Bay area. Between 1999 and 2006, light-duty vehicle ammonia emissions decreased by 38±6%, from 640±40 to 400±20mgkg−1. High time resolution measurements of ammonia made in summer 2001 at the same location indicate a minimum in ammonia emissions correlated with slower-speed driving conditions. Variations in ammonia emission rates track changes in carbon monoxide more closely than changes in nitrogen oxides, especially during later evening hours when traffic speeds are highest. Analysis of remote sensing data of Burgard et al. (Environmental Science Technology 2006, 40, 7018–22) indicates relationships between ammonia and vehicle model year, nitrogen oxides, and carbon monoxide. Ammonia emission rates from diesel trucks were difficult to measure in the tunnel setting due to the large contribution to ammonia concentrations in a mixed-traffic bore that were assigned to light-duty vehicle emissions. Nevertheless, it is clear that heavy-duty diesel trucks are a minor source of ammonia emissions compared to light-duty gasoline vehicles.
Keywords: Ammonia; NH; 3; Emissions; Trends; On-road; Vehicle; Light-duty; Heavy-duty; Nitrogen oxides; NO; x; Carbon monoxide; CO
Acidity of raindrop by uptake of gases and aerosol pollutants by D.M. Chate; P.C.S. Devara (pp. 1571-1577).
Below-cloud raindrops acidification simulated with a simple model incorporating gas–liquid equilibriums, gas-phase mass transfer, and catalyzed SO2 oxidation in aqueous phase with uptake of gases and scavenging of particles. Ionic contents of various species in raindrops of different size and pH are computed using one-dimensional time-variant model. The model results are based on SO2 and NH3 absorption and collection of calcium aerosols by raindrops with various collection mechanisms. Aqueous concentrations of (SO2)l and (NH3)l and their ionic components in raindrops are found to be increased with the fall distance from cloud base and decrease of drop size. The overall magnitude of pH enhances with the increase in drop size and transient position of raindrops in the atmosphere below the cloud base. The elevated ionic calcium in raindrops by impaction of calcium aerosols of higher inertia neutralizes the acidic components. Acidic ion contents in smaller droplets are found to be significant and resulted pH of raindrop increases with the size and neutralizing potential of alkaline species. The pH values of rainwater contents of predominant size raindrops in bulk samples corresponding to various rainfall intensities are higher as against the individual non-evaporating smaller raindrops. Results are important in view of the impact of showers on earth surfaces during rain containing large number of smaller droplets as compared to the acidification studies of bulk rainwater.
Keywords: Acid-rain; Collision efficiency; Reaction kinetics; Oxidation
Size segregated water uptake of the urban submicrometer aerosol in Beijing by A. Massling; M. Stock; B. Wehner; Z.J. Wu; M. Hu; E. Brüggemann; T. Gnauk; H. Herrmann; A. Wiedensohler (pp. 1578-1589).
Physical and chemical properties of submicrometer aerosol particles were measured in summer 2004 (June/July) and winter 2005 (January/February) in Beijing, Peoples Republic of China, using a Twin-Differential Mobility Particle Sizer (T-DMPS), a Hygroscopicity-Tandem Differential Mobility Analyzer (H-TDMA), and a Micro Orifice Uniform Deposit Impactor (MOUDI). Particle number–size distributions were measured in the diameter range Dp=3–800nm and hygroscopic properties were determined at initial dry particle diameters of Dp j ( j=30, 50, 80, 150, 250, and 350nm) at a relative humidity (RH) of 90%. Hygroscopic properties were compared with chemical analyses of aerosol samples taken with the MOUDI. Based on the hygroscopicity data, the total hygroscopic particle volume was modeled, including dependence on dry particle size, season and level of pollution using a simple approach.Overall, the chemical analysis showed ammonium sulfate to be the major inorganic component of the urban submicrometer aerosol in Beijing along with relatively high fractions of elemental carbon (10–25%) and organic matter (15–60%) depending on particle size and season.The hygroscopic growth distributions (H-TDMA) subdivided the aerosol population into three different groups of particles with varying growth factors depending on dry particle size, namely nearly hydrophobic (growth factor=0.96–1.07), less hygroscopic (1.06–1.29) and more hygroscopic (1.26–1.62).Hydrophobic particle fractions indicating freshly emitted soot/carbonaceous particles varied between 10 and 32% depending on dry particle size and season. During heavily polluted times, a decreasing number of hydrophobic particle fractions indicated that the urban submicrometer aerosol in Beijing was highly influenced by more aged aerosol transported from the industrial regions around Beijing containing sulfate as a major component.Based on model calculations, the urban submicrometer aerosol in Beijing showed strong compositional variations. The calculated total hygroscopic volume fractions varied between 16 and 65% depending on size, level of pollution and season.
Keywords: H-TDMA; DMPS; Hygroscopic behavior; Particle number–size distribution; Urban aerosol; Air pollution