Check out our New Publishers' Select for Free Articles

Atmospheric Environment (v.45, #19)

Editorial board (pp. i).

Secondary organic aerosol formation and source apportionment in Southeast Texas by Hongliang Zhang; Qi Ying (pp. 3217-3227).

The latest version of US EPA’s Community Multi-scale Air Quality (CMAQ v4.7) model with the most recent update on secondary organic aerosol (SOA) formation pathways was adapted into a source-oriented modeling framework to determine the contributions of different emission sources to SOA concentrations from a carbon source perspective in Southeast Texas during the 2000 Texas Air Quality Study (TexAQS 2000) from August 25 to September 5, 2000. A comparison of the VOC and SOA predictions with observations shows that anthropogenic emissions of long chain alkanes and aromatics are likely underestimated in the EPA’s Clean Air Interstate Rule (CAIR) inventory and the current SOA mechanism in CMAQ still under-predicts SOA. The peak SOA concentrations measured at La Porte are more accurately predicted by increasing the emissions of the anthropogenic SOA precursors by a factor of 5 although the overall precursor concentrations are better predicted by increasing the emissions by a factor of 2. A linear correlation between SOA and odd oxygen (ΔSOA/ΔO_x = 23.0–28.4 μg m⁻³/ppm O_x) can be found when they are formed simultaneously in the air masses passing the urban Houston area on high SOA days.Based on the adjusted emissions (a factor of 2 increase in the alkane and aromatics precursor emissions), approximately 20% of the total SOA in the Houston–Galveston Bay area is due to anthropogenic sources. Solvent utilization and gasoline engines are the main anthropogenic sources. SOA from alkanes and aromatics accounts for approximately 2–4% and 5–9% of total SOA, respectively. The predicted overall anthropogenic SOA concentrations are not sensitive to the half-life time used to calculate the conversion rate of semi-volatile organic compounds to non-volatile oligomers in the particle phase. The main precursors of biogenic SOA are sesquiterpenes, which contribute to approximately 12–35% of total SOA. Monoterpenes contribute to 3–14% and isoprene accounts for approximately 6–9% of the total SOA. Oligomers from biogenic SOA account for approximately 30–58% of the total SOA, indicating that long range transport is an important source of SOA in this region.► About 25–30% of the total SOA in the HGB area is due to anthropogenic sources. ►Major anthropogenic sources are solvent utilization and gasoline engines. ► Major precursors of biogenic SOA are sesquiterpenes and monoterpenes. ► SOA and O_x are linearly correlated on high SOA days (ΔSOA/ΔO_x = 28.4 μg m⁻³/ppm).

Keywords: SOA formation; Source-oriented photochemical model; Biogenic emission; AMS; CMAQ4.7; TexAQS 2000

Comparison of long-term PM_2.5 carbon measurements at an urban and rural location in New York by Oliver V. Rattigan; H. Dirk Felton; Min-Suk Bae; James J. Schwab; Kenneth L. Demerjian (pp. 3228-3236).

In order to provide consistency for PM_2.5 carbon data across urban and rural areas in the United States the Chemical Speciation Network (CSN) carbon sampling and analysis protocols were changed to resemble those of the Interagency Monitoring of Protected Visual Environments (IMPROVE). The “new” CSN carbon sampler, the URG-3000N, was introduced into the network in May 2007. In this paper collocated carbon measurements are used to (1) check for equivalency between the URG-3000N and the IMPROVE and (2) compare the URG-3000N and IMPROVE data with other collocated measurements. A sufficiently extensive dataset (over several years) enabled comparisons to be performed on a seasonal basis. The URG-3000N provided consistent measurements of PM_2.5 carbon with the IMPROVE at both urban and rural locations. In contrast measurements by the CSN MetOne were higher by approximately 20–30% for total carbon at the urban location and 40–50% at the rural location. This information is important for assessing discontinuities in time series data due to changes in the method as occurred to the CSN carbon in 2007.Display Omitted► Several PM_2.5 carbon methods are compared at an urban and rural location. ► URG-3000N and IMPROVE PM_2.5 carbon are consistent at both locations. ► Seasonal differences between IMPROVE PM_2.5 carbon and other methods are explored. ► Total carbon (TC) differences from 20 to 50% are observed. ► TC differences are attributed to a dynamic particle-gas phase equilibrium.

Keywords: PM; _2.5; carbon; CSN; IMPROVE; URG-3000N; TC

Modeling indoor air pollution from cookstove emissions in developing countries using a Monte Carlo single-box model by Michael Johnson; Nick Lam; Simone Brant; Christen Gray; David Pennise (pp. 3237-3243).

A simple Monte Carlo single-box model is presented as a first approach toward examining the relationship between emissions of pollutants from fuel/cookstove combinations and the resulting indoor air pollution (IAP) concentrations. The model combines stove emission rates with expected distributions of kitchen volumes and air exchange rates in the developing country context to produce a distribution of IAP concentration estimates. The resulting distribution can be used to predict the likelihood that IAP concentrations will meet air quality guidelines, including those recommended by the World Health Organization (WHO) for fine particulate matter (PM_2.5) and carbon monoxide (CO). The model can also be used in reverse to estimate the probability that specific emission factors will result in meeting air quality guidelines. The modeled distributions of indoor PM_2.5 concentration estimated that only 4% of homes using fuelwood in a rocket-style cookstove, even under idealized conditions, would meet the WHO Interim-1 annual PM_2.5 guideline of 35 μg m⁻³. According to the model, the PM_2.5 emissions that would be required for even 50% of homes to meet this guideline (0.055 g MJ-delivered⁻¹) are lower than those for an advanced gasifier fan stove, while emissions levels similar to liquefied petroleum gas (0.018 g MJ-delivered⁻¹) would be required for 90% of homes to meet the guideline. Although the predicted distribution of PM concentrations (median = 1320 μg m⁻³) from inputs for traditional wood stoves was within the range of reported values for India (108–3522 μg m⁻³), the model likely overestimates IAP concentrations. Direct comparison with simultaneously measured emissions rates and indoor concentrations of CO indicated the model overestimated IAP concentrations resulting from charcoal and kerosene emissions in Kenyan kitchens by 3 and 8 times respectively, although it underestimated the CO concentrations resulting from wood-burning cookstoves in India by approximately one half. The potential overestimation of IAP concentrations is thought to stem from the model’s assumption that all stove emissions enter the room and are completely mixed. Future versions of the model may be improved by incorporating these factors into the model, as well as more comprehensive and representative data on stove emissions performance, daily cooking energy requirements, and kitchen characteristics.► Model links stove emission performance with indoor air pollution concentrations. ► Modeled PM concentrations from rocket stove exceed WHO guidelines. ► Meeting WHO PM guidelines would require LPG-like emission performance.

Keywords: Emission factors; Biomass; Air quality guidelines; Stove testing

Implementation and initial application of the near-explicit Master Chemical Mechanism in the 3D Community Multiscale Air Quality (CMAQ) model by Qi Ying; Jingyi Li (pp. 3244-3256).

A modified Master Chemical Mechanism (MCM) with 4642 species and 13,566 reactions was incorporated into the 3D Community Multiscale Air Quality (CMAQ) model (CMAQ–MCM) and applied to study a three-week high ozone episode in Southeast Texas during the Texas Air Quality Study 2000 (TexAQS 2000). The 3D CMAQ–MCM model successfully reproduced the observed ozone concentrations throughout the Southeast Texas region, with model performance similar to that of the standard SAPRC07 mechanism. The CMAQ–MCM has been used to evaluate the VOC emission inventory by directly simulating the concentrations of a large number of VOCs. The simulated 1-h and 24-h average concentrations of major ozone precursor VOCs show that most of the alkanes and alkenes are universally lower than the observed values by a factor of 2–5. The under-prediction of ethane and propane is more significant, by a factor of approximately 5–10. Major aromatic compounds generally agree better with observation within a factor of 2. At the Clinton Drive site, most of the under-predictions occur in the afternoon when industrial facilities are in the immediate upwind direction. The observed concentrations of a number of the under-predicted species show strong correlations with temperature, suggesting that evaporative emissions are underestimated in the emission inventory.► The Master Chemical Mechanism is incorporated into the CMAQ model. ► Isoprene oxidizes faster in MCM than in SAPRC07 and leads to higher HCHO. ► Model results show under-predictions of primary VOC emissions in Southeast Texas. ► Evaporative emissions are underestimated in the emission inventory.

Keywords: Photochemical modeling; Near-explicit photochemical mechanism; Volatile organic compounds; TexAQS 2000; Emission inventory

Investigation of possible sources of water-soluble organic carbon particles observed with an online monitoring system by Seung S. Park; Jae M. Ko; Sung Y. Cho (pp. 3257-3266).

In this study, an instrument for the continuous measurements of water-soluble organic carbon (WSOC) component in fine particulate matter was developed and its field measurement results were presented. The instrument for collecting atmospheric aerosol particles for the online WSOC analysis uses an aerosol growth technology. Briefly, ambient particles, with aerodynamic diameters less than 2.5 μm, are collected via a cyclone inlet collector by rapidly mixing saturated water vapor with the ambient aerosol. The resulting supersaturated water vapor condenses on all the particles. The resulting liquid is separated from the air stream by an air–liquid separator, filtered, and the carbon content quantified using a total organic carbon analyzer, providing a continuous 4-min integral measurement. An evaluation of the accuracy of the online WSOC measurement system was performed by comparing the results with 24-h filter-based measurement data. The relationship between the 24-h averages of the 4-min data and the 24-h integrated data of the WSOC measurements indicated that the online WSOC concentration was 16% lower than that of the filter-based measurement.The online measurements of WSOC in fine particles were performed in September 2009 at a photochemical network near an industrial complex. Conditional probability functions were used to identify likely local emission source locations of the WSOC observed at the site, indicating that the major WSOC contribution to the site came mostly from the southeasterly (120−150°) and southwesterly (165–210°) directions, which brought air from a coal-fired power plant and traffic on the roads. Based on the temporal evolutions of SO₂ and WSOC concentrations, wind direction with respect to the station angle of individual sources, wind speed, and source distance, it was shown that the presence of concurrent transients in SO₂ and WSOC concentrations observed for a specific period is likely due to the influence of coal-fired power plants.► An instrument for online measurements of WSOC particles is developed. ► An online method and integrated filter-based measurements of WSOC are compared. ► Excursions in the WSOC observed could be due to plumes from coal-fired power plant.

Keywords: Water-soluble organic carbon; Online measurement; SO; ₂; Coal-fired power plants

Properties of coarse particles in the atmosphere of the United Kingdom by Yan-Ju Liu; Roy M. Harrison (pp. 3267-3276).

The recent rapid expansion of PM_2.5 monitoring alongside PM₁₀ has allowed estimation of concentrations of coarse particles (PM_2.5–10) by difference. This has been carried out for sites using comparable measurement techniques for both metrics, and the properties of the hourly average concentration data have been evaluated. In the UK atmosphere, coarse particles generally represent well under half of PM₁₀ mass. The ratio of PM_coarse to PM₁₀ averages 0.29 ± 0.14 ( n = 43) for FDMS measurements and 0.38 ± 0.30 ( n = 12) for TEOM measurements and does not show a very consistent pattern according to site type. The values are mostly higher for TEOM measurements than for FDMS which is explicable in terms of semi-volatile losses predominantly from fine particles in the TEOM. Sites where PM_coarse/PM₁₀ exceeds 0.5 generally have a marine or industrial influence. Correlations between hourly PM_2.5 and PM₁₀ are generally very high (mean R = 0.80 for FDMS data and mean R = 0.85 for TEOM data) whilst those between PM_coarse and PM_2.5 are very much lower (mean R = 0.09 for FDMS measurements and mean R = 0.41 for TEOM measurement sites). When inter-site correlations are examined between sites of similar characteristics within 30 km of one another, the inter-site correlation of PM_2.5 ( R = 0.56–0.87) is very much higher than that of PM_coarse ( R = 0.25–0.60). Coefficients of Divergence indicate lower spatial homogeneity for PM_coarse than for PM_2.5. When hourly data are used to construct pollution roses, it is typical for PM_2.5 and PM₁₀ to show a similar pattern dominated either by long-range transport or local traffic sources while PM_coarse can show quite a different pattern indicative of a different range of contributory sources. Plots of particle concentration versus wind speed show a monotonic decline of concentration with increasing wind speed for PM_2.5, but an initial decline and an increase at higher wind speeds for PM_coarse. There are relatively few datasets allowing an examination of temporal trend but those available for 4.5–10 years generally show no significant trend with time for fine or coarse particles, or for PM₁₀. Weekday/weekend and diurnal concentration patterns for coarse and fine particles show a strong anthropogenic influence on PM_coarse and a larger weekday/weekend difference for PM_coarse than PM_2.5. It is concluded that coarse and fine particles show very different behaviour as a result of their different sources and properties. The lower spatial homogeneity of coarse particles may be a contributory factor in why they appear to be less toxic than fine particles in epidemiological studies.► Coarse particle behaviour markedly differs from fine particles. ► Main sources of coarse particles in most cities are anthropogenic. ► Lower spatial uniformity of coarse than fine particles. ► Raises important implications for health effects studies.

Keywords: Coarse particles; PM; ₁₀; Particulate matter

Global aerosol model-derived black carbon concentration and single scattering albedo over Indian region and its comparison with ground observations by D. Goto; T. Takemura; T. Nakajima; K.V.S. Badarinath (pp. 3277-3285).

Black carbon (BC) aerosols through their light-absorbing properties create strong perturbation in the atmosphere by heating the atmosphere. BC mass concentration and single scattering albedo (SSA) are important parameters to investigate atmospheric heating. In the present study, measurements of BC and SSA over Indian region from the literature are summarized and compared with simulations by a global aerosol model SPRINTARS. It has been observed that BC emission inventory widely used in the world is underestimating and the model simulated SSA tends to be higher than observed-SSA. In addition to the inventory, we have run the global model using the different BC emission inventory interpolated by over Asia. The model runs with this inventory was found to provide comparable results with ground observations for BC and SSA. Aerosol radiative forcing due to direct effect (ADRF) over Indian region estimated to be −2.76 W m⁻² at the surface and −1.91 W m⁻² at the atmosphere using the modified emission inventory in the global aerosol model. The atmospheric heating is estimated to be +0.85 W m⁻², which is three times higher than the original emission inventory estimated value of +0.25 W m⁻². Results of the study suggest that the differences in various BC emission inventories widely used in the world’s research community should be studied for proper estimation of the aerosol radiative forcing over the Indian region.► We collected many measurements of BC and SSA in Indian region for model validation. ► We compared the measurements to results of our global aerosol model in Indian region. ► The BC emission widely used in the world underestimates BC and overestimates SSA. ► The model with the different BC emission provided closer results to the measurements. ► The difference in the atmospheric heating between two simulations was +0.85 W m⁻².

Keywords: Global aerosol model; Black carbon; Single scattering albedo; Radiative forcing

The significance of vehicle emissions standards for levels of exhaust pollution from light vehicles in an urban area by G.A. Rhys-Tyler; W. Legassick; M.C. Bell (pp. 3286-3293).

This paper addresses the research question “Are more stringent exhaust emissions standards, as applied to light vehicle type approval, resulting in reduced vehicle pollution in an urban area?” The exhaust emissions of a sample of over fifty thousand road vehicles operating in London were measured using roadside remote sensing absorption spectroscopy techniques (infrared and ultraviolet), combined with Automatic Number Plate Recognition for vehicle identification. Levels of carbon monoxide (CO), hydrocarbons (HC), nitric oxide (NO), and smoke (particulate) exhaust emissions are reported by vehicle class, fuel type, and Euro emissions standard. Emissions from petrol cars of each pollutant were all observed to display a statistically significant reduction with the introduction of each successive Euro emissions standard from Euro 1 onwards. However, Euro 2 diesel cars were observed to emit statistically higher rates of NO than either Euro 1 or Euro 3 standard diesel cars. The study also confirms the continuing ‘dieselisation’ of the UK passenger car fleet. Mean NO emissions from Euro 4 diesel cars were found to be 6 times higher than Euro 4 petrol cars, highlighting the need to develop a sound understanding of the current and future ‘in-use’ emissions characteristics of diesel vehicles, and their influence on local air quality. Smoke emissions from TXII London taxis (black cabs) were found to be statistically higher than either earlier TX1 or later TX4 model variants, with possible implications for local air quality policy interventions such as maximum age limits for taxis.► Euro standards have a significant influence on light vehicle tailpipe emissions. ► Petrol car NO, CO, HC, and smoke are reduced progressively from Euro 1 to Euro 4. ► NO emissions from Euro 2 diesel cars are statistically higher than Euro 1 and 3. ► Mean NO from Euro 4 diesel cars are 6 times higher than from Euro 4 petrol cars.

Keywords: Remote sensing; Vehicle exhaust emissions; London; Nitric oxide; Emissions standards

Effect of chemistry-transport model scale and resolution on population exposure to PM_2.5 from aircraft emissions during landing and takeoff by Saravanan Arunachalam; Binyu Wang; Neil Davis; Bok Haeng Baek; Jonathan I. Levy (pp. 3294-3300).

Atmospheric chemistry-transport models are often used to determine the marginal impact of emissions on air quality and public health, but the uncertainties related to modeling assumptions are rarely formally characterized from the perspective of health impact calculations. Aviation emissions are of increasing interest, due to the projected growth in aviation transport coupled with the decreasing emissions from other anthropogenic sources, but the geographic scale and resolution necessary to accurately characterize public health impacts from aviation are unclear, given the unique spatio-temporal pattern of aviation emissions. In this study, we estimate the incremental contribution of commercial aviation emissions during landing and takeoff (LTO) cycles from three U.S. airports – Atlanta’s Hartsfield-Jackson, Chicago’s O’Hare, and Providence’s T.F. Green – to fine particulate matter (PM_2.5) levels using the Community Multiscale Air Quality model (CMAQ), a comprehensive chemistry-transport air quality model. To evaluate the significance of model resolution and geographic scale, we ran a one-atmosphere version of CMAQ at 36-, 12-, and 4-km resolutions, and calculated the total population health risks at various distances from each airport. In spite of significant differences in maximum concentrations attributable to aviation emissions, total population health risks over the entire model domain were largely unaffected by model resolution, with a 2% difference in estimated mortality risks between the 36-km and 12-km resolution outputs. Analyses of model scale indicated that a 108 × 108 km domain centered on the airport captured most population exposure for primary components of PM_2.5, but total public health risks were dominated by populations at greater distances from the airport, given the contribution from secondary ammonium sulfate and nitrate, with 28–35% of health risks occurring more than 300 km from the airports. Our findings provide insight about the model resolution and geographic scales necessary for population risk assessment from LTO emissions, and demonstrate the robustness of risk-based prioritization across multiple grid resolutions.► Used a CMAQ application to study AQ & health risks from aircraft emissions during LTO. ► Focused on PM_2.5 impacts from 3 U.S. airports – Atlanta, Chicago and Providence. ► Total population health risks unaffected by model resolution: 2% change between grids. ► 28–35% of health risks occur >300-km from airports, due to PM secondary components. ► Relative importance of species depend on choice of max. or total population impacts.

Keywords: Aircraft emissions; Air quality; CMAQ; Particulate matter; Grid resolution; Population exposure

An evaluation of EPA’s National-Scale Air Toxics Assessment (NATA): Comparison with benzene measurements in Detroit, Michigan by Barbara Jane George; Bradley D. Schultz; Ted Palma; Alan F. Vette; Donald A. Whitaker; Ronald W. Williams (pp. 3301-3308).

The U.S. EPA periodically evaluates ambient concentrations, human exposures, and health risks for 180 hazardous air pollutants plus diesel particulate matter using modeled estimates from the National-Scale Air Toxics Assessment (NATA). NATA publishes estimates at the spatial resolution of U.S. Census tracts, which are subdivisions of a county. These local scale, model-predicted estimates from NATA are used extensively in community-based assessments; however, evaluation of NATA’s ambient concentrations and human exposure estimates against measurement data has been limited to date. This paper compares modeled annual average benzene results from the 2002 NATA with measured results from the 2004 to 2007 Detroit Exposure and Aerosol Research Study (DEARS) as a case study of the quality of NATA results. NATA model estimates support community-scale characterization and assessment. Benzene is particularly important as it was estimated by the 2002 NATA as the largest single air toxic pollutant in terms of cancer risk in the U.S. We found that the average ambient concentrations of benzene predicted by NATA were within 5 percent, on average, of the 24-h integrated average ambient concentrations measured in DEARS. The NATA human exposure estimates, which include only outdoor sources for benzene, were, on average, approximately half the measured breathing zone concentrations from DEARS. Our analyses support that the factors driving higher DEARS personal benzene concentrations relative to the NATA predicted exposure values are likely due, at least in part, to indoor sources. This work points to further community-scale modeling research to improve characterizations and assessments of human exposures.► Evaluated benzene airborne concentrations and human exposures at community scale. ► Modeled ambient estimates on average within 5 percent measured concentrations. ► Modeled human exposure estimates on average half personal concentrations. ► Higher measured personal concentrations likely due in part to indoor sources.

Keywords: Ambient concentration; Human exposure; Personal exposure; Detroit Exposure and Aerosol Research Study

Long-term changes in PM₁₀ levels in urban air in relation with air quality control efforts by Ki-Hyun Kim; Zang-Ho Shon (pp. 3309-3317).

In an effort to assess long-term variations of urban air quality over a broad spatial scale, the concentrations of PM₁₀ (particulate matters with aerodynamic size below 10 μm) measured from a total of 16 urban roadside (U-RS) stations in Korea over a decadal period (1998 and 2008) were analyzed in a number of respects. As a major criterion for evaluation, these PM data were examined with respect to landmarking active clean-up activities (e.g., Natural Gas Vehicle Supply (NGVS) program enforced since 2000 and upgrading of fuel quality since 2004) and emission control retrofits since 2003 throughout major urban areas in Korea. The mean concentrations of PM₁₀ from all 16 U-RS stations varied from 51.3 ± 10.3 (before 2000) to 70.3 ± 19.4 μg m⁻³ (after 2001). The results derived from 4 regional background stations were also analyzed as a reference to the urban data sets. The analysis of our PM data between before and after such clean-up activity for air quality indicates the existence of highly diversified temporal patterns. The measured PM values from only a few U-RS stations exhibited statistically significant declining trends over a decadal period. It is thus concluded that the effect of clean-up activity like NGVS and emission control retrofits, although claimed to make zero-emissions of fine particles, did not result in an overall reduction in PM₁₀ levels.► In an effort to assess long-term variations of urban air quality over a broad spatial scale. ► The concentrations of PM₁₀ were measured from a total of 16 urban roadside (U-RS) stations. ► The results of this study provide the effect of control efforts on PM level changes in Korea. ► The effect of emission control retrofits did not result in an overall reduction in PM₁₀ levels.

Keywords: PM; Mann–Kendall test; Roadside; Spatiotemporal; Size fraction; Natural gas vehicle

Intercontinental influence of NO_x and CO emissions on particulate matter air quality by Eric M. Leibensperger; Loretta J. Mickley; Daniel J. Jacob; Steven R.H. Barrett (pp. 3318-3324).

Anthropogenic emissions of nitrogen oxides (NO_x ≡ NO + NO₂) and carbon monoxide (CO) affect particulate matter (PM) air quality on an intercontinental scale by changing background concentrations of oxidants (OH, ozone, H₂O₂) and thus increasing the oxidation rate of sulfur dioxide (SO₂) to sulfate and NO_x to nitrate. We conduct sensitivity simulations with the GEOS–Chem chemical transport model and find that these intercontinental influences of NO_x and CO emissions on PM can be greater than those from SO₂ emissions (a direct PM precursor). The intercontinental impact of oxidant precursors is greatest in receptor regions with high domestic SO₂, NO_x, and ammonia emissions and hence already high levels of PM. US NO_x and CO emissions increase annual mean PM in northern Europe and eastern China by up to 0.25 μg m⁻³. The increase in Europe is mostly as sulfate, whereas in China it is mostly as nitrate. East Asian NO_x and CO emissions have a weaker intercontinental influence (∼0.2 μg m⁻³ in northern Europe, ∼0.1 μg m⁻³ in the eastern US). These intercontinental effects of NO_x and CO emissions on PM depend in a complex way on the chemical environment of receptor regions. Intercomparison of results from different models would be of great interest.► Aerosol formation is enhanced by distant NO_x and CO emissions. ► NO_x and CO emissions affect intercontinental PM air quality more than SO₂. ► Intercontinental effect of NO_x and CO is largest where air quality is already poor.

Keywords: Air quality; Intercontinental transport; Aerosols

The impact of local sources and meteorological factors on nitrogen oxide and particulate matter concentrations: A case study of the Day of Atonement in Israel by Uri Dayan; Yigal Erel; Jacob Shpund; Levana Kordova; Arye Wanger; James J. Schauer (pp. 3325-3332).

Measurements of the atmospheric concentrations of NO_x and particulate matter (PM) in three urban centers in Israel before, during, and after the Day of Atonement were performed for nine consecutive years (2000–08). This enabled to investigate the significance of local versus long-range sources of pollution and probe the effect of meteorological conditions (synoptic systems, ventilation rates, height of surface boundary layer, and wind speed) on level of pollution. During the Day of Atonement all traffic and most of the industrial activities cease in the Jewish populated parts of the country. We observed that in spite of this, concentrations of particulate matter (PM_2.5 and PM₁₀) are very similar in all three urban centers during the Day of Atonement to the days before and after. Moreover, PM levels during the Day of Atonement are generally higher during Red Sea trough synoptic conditions which carry air from the Saudi and Jordanian deserts in the east and southeast relative to Persian Trough synoptic conditions which bring air from the eastern Mediterranean and the Black Sea region in the north-west. In addition, 55% of the variation in PM values during the nine days of Atonement included in this study can be explained by changes in ventilation rates of the atmosphere, namely the product of the mixing depth and a representative boundary layer wind speed. Thus, long-range sources and local mixing conditions determine the concentrations of PM in the atmosphere of Israel as expected from their long residence time. On the other hand, NO_x concentrations during the Day of Atonement are significantly lower than the days before and after, reflecting NO_x short residence time in the atmosphere and the strong influence of local emission sources. Furthermore, the difference in concentrations of NO_x in different Days of Atonement cannot be accounted for either by different synoptic conditions or by variations in ventilation rates, height of surface boundary layer, and wind speed. They are determined by the combination of local and regional sources of emission and the meteorological conditions which control their transport from these nearby sources to the sampling station.► Concentrations of NO_x and PM (10/2.5) were measured in three major urban centers in Israel before, during, and after the Day of Atonement for 2000–08. ► During the Day of Atonement all traffic and most of the industrial activities cease in the Jewish populated parts of the country. ► Due to their long residence time, concentrations of PM have not changed much during these three days. ► NO_x concentrations strongly influenced by local emission sources and reflecting a pollutant of short residence time were significantly lower during the Day of Atonement.

Keywords: PM; NO; _x; Pollution sources; Short-lived pollutants; Long-lived pollutants

Volatile organic compound emissions from switchgrass cultivars used as biofuel crops by A.S.D. Eller; K. Sekimoto; J.B. Gilman; W.C. Kuster; J.A. de Gouw; R.K. Monson; M. Graus; E. Crespo; C. Warneke; R. Fall (pp. 3333-3337).

Volatile organic compound (VOC) emission rates during the growth and simulated harvest phases were determined for switchgrass ( Panicum virgatum) using laboratory chamber measurements. Switchgrass is a candidate for use in second-generation (cellulosic) biofuel production and the acreage dedicated to its growth in the USA has already increased during the past decade. We estimate that the yearly emissions from switchgrass plantations, including both the growth and harvest phases will be on the order of 3 kg C ha⁻¹ methanol, 1 kg C ha⁻¹ acetaldehyde, 1 kg C ha⁻¹ acetone, 0.9 kg C ha⁻¹ monoterpenes, 0.5 kg C ha⁻¹ isoprene + another compound, most likely 1-penten-3-ol, 0.2 kg C ha⁻¹ hexenals, and 0.1 kg C ha⁻¹ hexenols. These emission rates are much lower than those expected from Eucalyptus or poplar plantations, which are other potential biofuel crops and have significantly higher VOC emissions, suggesting that the choice of species in the production of biofuels could have serious implications for regional air quality.

Keywords: Volatile organic compounds; Biofuel; Switchgrass; Panicum virgatum

Barriers and opportunities for passive removal of indoor ozone by Elliott T. Gall; Richard L. Corsi; Jeffrey A. Siegel (pp. 3338-3341).

This paper presents a Monte Carlo simulation to assess passive removal materials (PRMs) that remove ozone with no additional energy input and minimal byproduct formation. Distributions for air exchange rate in a subset of homes in Houston, Texas, were taken from the literature and combined with background ozone removal rates in typical houses and previous experimentally determined ozone deposition velocities to activated carbon cloth and gypsum wallboard PRMs. The median ratio of indoor to outdoor ozone was predicted to be 0.16 for homes with no PRMs installed and ranged from 0.047 to 0.12 for homes with PRMs. Median values of ozone removal effectiveness in these homes ranged from 22% to 68% for the conditions investigated. Achieving an ozone removal effectiveness above 50% in half of the homes would require installing a large area of PRMs and providing enhanced air speed to transport pollutants to PRM surfaces. Challenges associated with achieving this removal include optimizing indoor transport and aesthetic implications of large surface areas of PRM materials.

Keywords: Indoor air quality; Passive pollutant removal; Low-energy air cleaning

Corrigendum to “Odour emissions from a waste treatment plant using an inverse dispersion technique [Atmos. Environ. 45, 1639–1647]” by G. Schauberger; M. Piringer; W. Knauder; E. Petz (pp. 3342-3342).

Sections

Personal tools

Atmospheric Environment (v.45, #19)

Sections

Personal tools

Local resources

Atmospheric Environment (v.45, #19)