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Atmospheric Environment (v.41, #19)
Assessing the photochemical impact of snowNOx emissions over Antarctica during ANTCI 2003 by Yuhang Wang; Yunsoo Choi; Tao Zeng; Douglas Davis; Martin Buhr; L. Gregory Huey; William Neff (pp. 3944-3958).
Surface and aircraft measurements show large amounts of reactive nitrogen over the Antarctic plateau during the ANTCI 2003 experiment. We make use of 1-D and 3-D chemical transport model simulations to analyze these measurements and assess the photochemical impact of snowNOx emissions. Boundary layer heights measured by SODAR at the South Pole were simulated reasonably well by the polar version of MM5 after a modification of ETA turbulence scheme. The average of model-derived snowNOx emissions(3.2–4.2×108moleccm-2s-1) at the South Pole is similar to the measured flux of3.9×108moleccm-2s-1 during ISCAT 2000. Daytime snowNOx emission is parameterized as a function of temperature and wind speed. Surface measurements of NO,HNO3 andHNO4, and balloon measurements of NO at the South Pole are reasonably simulated by 1-D and 3-D models. Compared to Twin Otter measurements of NO over plateau regions, 3-D model simulated NO concentrations are at the low end of the observations, suggesting either that the parameterization based on surface measurements at the South Pole underestimates emissions at higher-elevation plateau regions or that the limited aircraft database may not be totally representative for the season of the year sampled. However, the spatial variability of near-surface NO measured by the aircraft is captured by the model to a large extent, indicating that snowNOx emissions are through a common mechanism. An average emission flux of0.25kgNkm-2month-1 is calculated for December 2003 over the plateau (elevation above 2.5km). About 50% of reactive nitrogen is lost by deposition and the other 50% by transport. The 3-D model results indicate a shallow but highly photochemically active oxidizing “canopy” enshrouding the entire Antarctic plateau due to snowNOx emissions.
Keywords: Antarctica; Photochemistry and transport; Snow emissions; Nitrogen flux; ANTCI
Spatio-temporal variability of satellite-derived aerosol optical thickness over Northeast Asia in 2004 by Kwon Ho Lee; Young Joon Kim; Wolfgang von Hoyningen-Huene; John P. Burrow (pp. 3959-3973).
In this study a modified Bremen aerosol retrieval (BAER) method was used to retrieve aerosol optical thickness (AOT) over both land and ocean using moderate resolution imaging spectro-radiometer (MODIS) data over Northeast Asia for a full year during 2004. Retrieved MODIS AOT data were in good agreement with data obtained from a ground-based AERONET sunphotometer ( r=0.90, linear slope=0.89). Seasonal variation analysis of AOT revealed maximum values in summer (∼0.41) and minimum values in winter (∼0.25). The contribution of each aerosol type to total AOT was estimated for each pixel. A spectral shape fitting procedure was used to select the optimum aerosol model for AOT retrieval among six aerosol types: urban, rural, maritime, tropospheric, Asian dust, and biomass burning. The spatio-temporal distribution of average AOT was analyzed for the following five sectors in Northeast Asia: (I) East China, (II) Yellow Sea, (III) Korea, (IV) East Sea, and (V) South Sea plus a part of Japan. Maximum AOT values of 0.75±0.18 were measured over sector (I) in summer, while minimum values of 0.10±0.02 were recorded over sector (IV) in winter. AOT estimates over sector (I) were much higher than those of other sectors due to an increased contribution to the total AOT by fine urban aerosol, which contributed up to 56.5% of the total AOT.
Keywords: BAER; MODIS; Sunphotometer; AOT; Aerosol type
Identification of sources of atmospheric PM at the Pittsburgh Supersite—Part III: Source characterization by Keith J. Bein; Yongjing Zhao; Murray V. Johnston; Anthony S. Wexler (pp. 3974-3992).
Single-particle mass spectrometry data collected during the Pittsburgh Supersite experiment was used to isolate an episode on 27 October 2001 when the measurement site was primarily influenced by emissions from coal combustion sources. Results showed that (a) 60–80% of the particles detected during this event belonged to the Na/Si/K/Ca/Fe/Ga/Pb particle class associated with coal combustion emissions, (b) observation of this class was an isolated event occurring only during the hours of 06:00–14:00 EST, and (c) the detection of these particles was highly correlated with shifts in wind direction. Coincident SMPS, TEOM PM2.5, SO2, NO x, and O3 measurements were in excellent agreement with the single-particle results in terms of both identifying and characterizing this event. The three most likely point sources of these particles were isolated and Gaussian plume dispersion models were used in reverse to predict their particle number, particle mass, and gas phase emissions. Calculated mass emission rates were in general agreement with the US EPA National Emissions Inventory (NEI) database emissions estimates and the Title V PM10 limit. The largest of the three sources emits about 2.4×1017 fine and ultrafine particles per second.
Keywords: Single-particle mass spectrometry; Coal combustion particles; Coal-fired power plant plumes; Size-distributed particle number emission rates; Particle mass emission rates; Pittsburgh Supersite experiment
Laboratory evaluation of a novel thermal dissociation chemiluminescence method for in situ detection of nitrous acid by Idalia M. Pérez; Paul J. Wooldridge; Ronald C. Cohen (pp. 3993-4001).
We describe a new laboratory-based method for in situ detection of nitrous acid (HONO) using a combination of thermal dissociation (TD) and chemiluminescent (CL) detection of nitric oxide. A prototype was built using a commercial NO sensor. Laboratory tests for possible chemical interferences show that measurements are affected in predictable ways byNO2, peroxy nitrates, alkyl nitrates,HNO3,O3 andH2O.
Keywords: Nitrous acid; Instrument; Nitrogen oxides; HONO
Secondary aerosol formation through photochemical reactions estimated by using air quality monitoring data in Taipei City from 1994 to 2003 by S.-C. Shuenn-Chin Chang; C.-T. Chung-Te Lee (pp. 4002-4017).
Analyses of diurnal patterns of PM10 in Taipei City have been performed in this study at different daily ozone maximum concentrations (O3,max) from 1994 to 2003. In order to evaluate secondary aerosol formation at different ozone levels, CO was used as a tracer of primary aerosol, and O3,max was used as an index of photochemical activity. Results show that when O3,max exceeds 120ppb, the highest photochemical formation of secondary aerosol can be found at 15:00 (local time). The produced secondary aerosol is estimated to contribute 30μgm−3 (43%) of PM10 concentration, and about 77% of the estimated secondary PM10 is composed of PM2.5. The estimated maximum concentration of secondary aerosol occurs 2–3h later than the maximum ozone concentration. As revealed in an O3 episode, PM10 and PM2.5 vary consistently with O3 at daytime, which suggests that they are mostly secondary aerosols produced from photochemical reactions. Data collected from Taipei aerosol supersite in 2002 indicates that for all O3 levels, summertime PM2.5 is composed of 23%, 20%, 9%, and 7% of organic carbon, sulfate, nitrate, and elemental carbon, respectively. Aerosol number and volume size spectra are dominated by submicron particles either from pollution transport or photochemical reactions. Secondary PM10 concentrations show increasing tendencies for the time between 15:00 and 19:00 from 1994–1996 to 2001–2003. This reveals that the abatement of secondary PM10 becomes more important after pronounced primary PM10 reduction in a metropolis.
Keywords: Air quality monitoring; Aerosol supersite; Ozone; Photochemical activities; Secondary aerosol
Passive flux sampler for measurement of formaldehyde emission rates by Naohide Shinohara; Minoru Fujii; Akihiro Yamasaki; Yukio Yanagisawa (pp. 4018-4028).
A new passive flux sampler (PFS) was developed to measure emission rates of formaldehyde and to determine emission sources in indoor environments. The sampler consisted of a glass Petri dish containing a 2,4-dinitrophenyl hydrazine (DNPH)-impregnated sheet. At the start of sampling, the PFS was placed with the open face of the dish on each of the indoor materials under investigation, such as flooring, walls, doors, closets, desks, beds, etc. Formaldehyde emitted from a source material diffused through the inside of the PFS and was adsorbed onto the DNPH sheet. The formaldehyde emission rates could be determined from the quantities adsorbed. The lower determination limits were 9.2 and 2.3μgm−2h−1 for 2- and 8-h sampling periods. The recovery rate and the precision of the PFS were 82.9% and 8.26%, respectively. The emission rates measured by PFS were in good agreement with the emission rates measured by the chamber method ( R 2=0.963). This shows that it is possible to take measurements of the formaldehyde emission rates from sources in a room and to compare them. In addition, the sampler can be used to elucidate the emission characteristics of a source by carrying out emission measurements with different air-layer thicknesses inside the PFS and at different temperatures. The dependency of the emission rate on the thickness of the air layer inside the PFS indicated whether the internal mass transfer inside the source material or the diffusion in the gas-phase boundary layer controlled the formaldehyde emission rate from a material. In addition, as a pilot study, the formaldehyde emission rates were measured, and the largest emission source of formaldehyde could be identified from among several suspected materials in a model house by using the PFS.
Keywords: Flux; Emission source; Formaldehyde; Boundary layer; Rate-limiting process; Passive sampler
Odors and volatile organic compounds released from ventilation filters by Marko Hyttinen; Pertti Pasanen; Bjorkroth Marko Björkroth; Pentti Kalliokoski (pp. 4029-4039).
Used supply air filters were studied by sensory and chemical methods. In addition, filter dust was examined by thermodesorption/cold trap (TCT) and headspace (HS) devices connected to a GC–MS. The prefilter was the main odor source in the ventilation unit, but when humidifier was turned on odor was released mainly from the fine filter. However, the effect of the relative humidity (RH) was only temporary. At the same time, there was an increase in the concentration of aldehydes after the filters. Aldehydes, carboxylic acids, and nitrogen-containing organic compounds were the main emission products in the thermodesorption analyses of the filter dust. Many of these compounds have low odor threshold values and, therefore, contribute to the odor released from the filters. Especially, the role of aldehydes seems to be important in the odor formation.
Keywords: Ventilation filters; Odor; VOC; Aldehydes; Relative humidity
Urban air pollution modelling and measurements of boundary layer height by F. Davies; D.R. Middleton; K.E. Bozier (pp. 4040-4049).
An urban field trial has been undertaken with the aim of assessing the performance of the boundary layer height (BLH) determination of two models: the Met Office Unified Model (UM) and a Gaussian-type plume model, ADMS. Pulsed Doppler lidar data were used to measure mixing layer height and cloud base heights for a variety of meteorological conditions over a 3 week period in July 2003. In this work, the daily growth and decay of the BLH from the lidar data and model simulations for 5 days are compared. The results show that although the UM can do a good job of reproducing the boundary layer growth, there are occasions where the BLH is overestimated by 30–100%. Within dispersion models it is the BLH that effectively limits the height to which pollution disperses, so these results have very important implications for pollution dispersion modelling. The results show that correct development of the boundary layer in the UM is critically dependant on morning cloud cover. The ADMS model is used routinely by local authorities in the UK for local air-quality forecasting. The ADMS model was run under three settings; an ‘urban’ roughness, a ‘rural’ roughness and a ‘transition’ roughness. In all cases, the ‘urban’ setting over estimated the BLH and is clearly a poor predictor of urban BLH. The ‘transition’ setting, which distinguishes between the meteorological data input site and the dispersion modelling site, gave the best results under the well mixed conditions of the trial.
Keywords: Air-quality forecasting; Dispersion models; Doppler lidar; Mixing height; Urban boundary layer
Airborne desert dust and aeromicrobiology over the Turkish Mediterranean coastline by Dale W. Griffin; Nilgün Kubilay; Mustafa Koçak; Mike A. Gray; Timothy C. Borden; Eugene A. Shinn (pp. 4050-4062).
Between 18 March and 27 October 2002, 220 air samples were collected on 209 of 224 calendar days, on top of a coastal atmospheric research tower in Erdemli, Turkey. The volume of air filtered for each sample was 340liters. Two hundred fifty-seven bacterial and 2598 fungal colony forming units (CFU) were enumerated from the samples using a low-nutrient agar. Ground-based dust measurements demonstrated that the region is routinely impacted by dust generated regionally and from North Africa and that the highest combined percent recovery of total CFU and African dust deposition occurred in the month of April (93.4% of CFU recovery and 91.1% of dust deposition occurred during African dust days versus no African dust present, for that month). A statistically significant correlation was observed (peak regional African dust months of March, April and May; rs=0.576, P=0.000) between an increase in the prevalence of microorganisms recovered from atmospheric samples on dust days (regional and African as determined by ground-based dust measurements), versus that observed on non-dust days. Given the prevalence of atmospherically suspended desert dust and microorganisms observed in this study, and that culture-based studies typically only recover a small fraction (<1.0%) of the actual microbial population in any given environment, dust-borne microorganisms and other associated constituents (organic detritus, toxins, etc.) may play a significant role in the regional human and ecosystem health.
Keywords: Turkey; Middle East; Desert dust; African dust; Microbiology; Aerobiology; Bacteria; Fungi; Public health; Mediterranean; Ecosystem health
The variation of methane emission from freshwater marshes and response to the exogenous N in Sanjiang Plain Northeast China by Lihua Zhang; Changchun Song; Dexuan Wang; Yiyong Wang; Xiaofeng Xu (pp. 4063-4072).
The methane emitted from freshwater marsh is the difference between the production and oxidation ofCH4 which reaches the atmosphere via diffusion, ebullition, or by passage through aerenchymous tissues of higher plants. To evaluate the variation ofCH4 emission and the effects of increased exogenous N onCH4 emission, we have raised in situ the exogenous N with the rates of0gNm-2 (control),6gNm-2 (low nitrogen level),12gNm-2 (medial nitrogen level) and24gNm-2 (high nitrogen level), respectively, in Sanjiang Plain marsh ecosystem Northeast China.CH4 emissions were measured using the static chamber and gas chromatogram techniques. The daily averageCH4 emission during the different growing stages from the marsh varies from-0.06 to13.54mgCH4m-2h-1 with the daily observation. The exogenous N significantly increased the mean seasonalCH4 emission rate by 181% (low nitrogen level,P<0.01), 254% (medial nitrogen level,P<0.01) and 155% (high nitrogen level,P<0.01), respectively. The effects of exogenous N strongly interacted with the plant aboveground biomass, which was a variable explaining most variation inCH4 emission. We also find the net effect of exogenous N onCH4 emission from freshwater marshes most likely depends on the counterbalance between the N-induced increases inCH4 production and oxidation, as a N excess may result in the inhibition ofCH4 emission, and in the stimulation ofCH4 emission.
Keywords: Variation; Exogenous N; Methane emission; Freshwater marshes; The Sanjiang Plain
Composition of PM2.5 during the summer of 2003 in Research Triangle Park, North Carolina by M. Michael Lewandowski; Mohammed Jaoui; Tadeusz E. Kleindienst; John H. Offenberg; Edward O. Edney (pp. 4073-4083).
A field study was carried out during the summer of 2003 to examine the overall composition of fine particulate matter (PM2.5) in Research Triangle Park, North Carolina, USA, with particular emphasis on polar compounds from secondary organic aerosol (SOA). Collected samples were examined for gravimetric mass, organic and elemental carbon concentrations, inorganic ion concentrations, and detailed organic composition. On average, the ambient PM2.5 was found to consist of 41% organic matter, 2% elemental carbon, 12% ammonium, 37% sulfate, and less than 1% nitrate and oxalate. Mass concentrations ranged from 6.4 to 31.4μgm−3. The acidity of the aerosol was also estimated, and higher PM2.5 and organic mass concentrations were generally observed under acidic conditions. A suite of chemical derivatization methods was used in conjunction with gas chromatography–mass spectrometry (GC–MS) to identify and quantify 29 polar organic compounds. Most of these compounds have been previously identified in laboratory photooxidation studies from hydrocarbon precursors, including isoprene, monoterpenes, β-caryophyllene, and toluene. From laboratory studies, several of these polar compounds have been proposed as tracers for SOA, and concentrations measured in this study indicate the contributions of the precursor hydrocarbons to ambient SOA could be important. Some of the organic tracers, particularly those associated with isoprene SOA, represented a greater fraction of the organic carbon when the aerosol was acidic.
Keywords: PM; 2.5; Secondary organic aerosol; Polar organic compounds; GC–MS
Use of an expanded receptor model for personal exposure analysis in schoolchildren with asthma by Weixiang Zhao; Philip K. Hopke; Erwin W. Gelfand; Nathan Rabinovitch (pp. 4084-4096).
An expanded receptor model was applied to identify and apportion the PM2.5 sources that were common to three different environments (personal, indoor: inside school, and outdoor: outside school) resulting in exposure to asthmatic children who attended a school in Denver, CO for children with moderate to severe asthma. Four resolved external sources and three internal sources were resolved from the PM2.5 data for three different environments. Secondary nitrate and motor vehicle emissions were the two largest external sources in this study. Cooking was the largest internal source. A significant influence of indoor smoking on daily personal exposures to particles was observed for those houses in which smokers reside and the environmental tobacco smoke contribution correlated with urinary cotinine levels in these urban schoolchildren. The influence of the high traffic flow outside the school on the indoor air quality was also observed. The identification and apportionment of these sources will support a subsequent investigation of the potency of air pollution sources on asthma severity in children and provide a better understanding of potential mechanisms of asthma exacerbation.
Keywords: Exposure analysis; Receptor model; Source apportionment; Environmental tobacco smoking; Asthma; Children; Urinary cotinine
Kinetics of atmospheric oxidation of nitrous acid by oxygen in aqueous medium by Punit K. Mudgal; S.P. Bansal; K.S. Gupta (pp. 4097-4105).
The facts that the high concentrations of nitrous acid have been reported in dew, fog, rain and cloud water and that its oxidation by dissolved oxygen is very fast in freezing conditions have led us to study the kinetics of aqueous phase oxidation of nitrous acid by dissolved oxygen in the pH range 1.0–4.5 at 30°C. The reaction was followed by measuring [O2] and under pseudo-first-order conditions the results were in agreement with the rate law:-d[O2]t/dt=k0[NIII]02[H+]2[O2]t/(Ka+[H+])2,where k0 is third-order composite rate coefficient and Ka is the dissociation constant of HNO2. The values of k0 and Ka were determined to be 1×102L2mol−2s−1 and 3.84×10−4, respectively.Consistent with the kinetics results two alternative mechanisms have been considered. The first of these mechanisms assumes an intermediate complex formation, [HNO2.O2], by the reaction of HNO2 and O2 in a rapid pre-equilibrium, followed by the reaction of this intermediate with another molecule of HNO2. The second mechanism, originally proposed by Damschen and Martin [1983. Aqueous aerosol oxidation of nitrous acid by O2, O3 and H2O2. Atmospheric Environment 17, 2005–2011], assumes the formation of a dimer, [HNO2]2, in a rapid pre-equilibrium followed by the reaction of the dimer with O2 to form HNO3. The application of the mechanisms to fast oxidation of nitrite by dissolved oxygen under freezing conditions is discussed.
Keywords: Nitrite; Nitrous acid; Nitric acid; Oxygen; Oxidation; Kinetics; Autoxidation
Sampling artefacts, concentration and chemical composition of fine water-soluble organic carbon and humic-like substances in a continental urban atmospheric environment by Imre Salma; Rita Ocskay; Xuguang Chi; Willy Maenhaut (pp. 4106-4118).
Water-soluble organic carbon (WSOC) and atmospheric humic-like substances (HULIS) were investigated for urban PM2.5-fraction aerosol samples, which were collected with the tandem filter method on quartz fibre filters over a non-heating spring season. Sampling artefacts were of importance for all organic chemical fractions, and the back-to-front-filter concentration ratios were on average 28% for WSOC and 17% for HULIS and organic carbon (OC). The difference in the ratios indicates that the water-soluble organics play a more important role in adsorptive artefacts than the organic matter (OM) in general. The results emphasize the need for an appropriate sampling and/or correction method for measuring particulate organic substances in urban environments. The corrected atmospheric concentration of HULIS, obtained by subtracting the back-filter from the front-filter data, was on average 2μgm−3; which represented 6% of the mean PM2.5 particulate mass, and it made up 45% of the secondary OC. The HULIS carbon accounted for 20% of the OC and 62% of the WSOC, while WSOC made up 32% of OC. The major element composition of HULIS, expressed in molar ratios, was C:H:O:N=22:32:10:1. The molar H/C ratio of 1.49 implies the presence of unsaturated organic compounds, although these were depleted in comparison with rural aerosol or standard fulvic acids. The molar O/C ratio of 0.47 indicates the existence of oxygenated functional groups; comparison to rural aerosol suggests that the (fresh) urban-type aerosol is less oxidized (and, therefore, less water soluble as well) than the rural one. The OM/OC mass conversion factor for the isolated (water-soluble) HULIS was derived to be 1.81. It was inferred from comparisons with published data that there are substantial differences in abundance and chemical composition of HULIS for different environments.
Keywords: HULIS; WSOC; OC; Carbon balance; OM/OC mass conversion factor
Characteristics of regional nucleation events in urban East St. Louis by Shi Qian; Hiromu Sakurai; Peter H. McMurry (pp. 4119-4127).
Continuous measurements of aerosol size distributions (3nm–2μm) were carried out over a 26 month period (1 April 2001–31 May 2003; 650 days with valid data) in urban East St. Louis, IL, as a part of the US Environmental Protection Agency's Supersite program. This paper analyzes data for the 155 days on which “regional nucleation events” were observed during this study. Such events were observed during every month of the study except January 2003. We observed some differences, however, between events in the summer (defined here as April–September) and winter (December–February). Regional nucleation events were observed more frequently in summer months (36±13% of days) than in winter (8±7%), and nucleated particles grew faster in the summer (6.7±4.8nmh−1) than in winter (1.8±1.9nmh−1). The daily maximum in the number concentration of nanoparticles formed by nucleation (4.8±3.5×104cm−3) was highly variable and showed no clear seasonal dependence. Particle formation increased particle concentrations by an average factor of 3.1±2.8. Maximum daily rates of 3nm particle production (17±20cm−3s−1) were also highly variable and without a clear seasonal dependence. During these events, particle formation rates were typically near their maxima at 08:00–09:00 a.m., but particle production sometimes persisted at diminishing rates until late in the afternoon (15:00–16:00 p.m.).
Keywords: New particle formation; Nucleation; Ultrafine aerosol; Nanoparticle; Urban aerosol
Optical properties of tropospheric aerosols based on measurements of lidar, sun-photometer, and visibility at Chung-Li (25°N, 121°E) by C.-W. Chih-Wei Chiang; Wei-Nai Chen; Wen-An Liang; Subrata Kumar Das; J.-B. Jan-Bai Nee (pp. 4128-4137).
We have used lidar, sun-photometer, and the visibility measurements to investigate the optical properties of aerosols in the lower air. The observations were performed at Chung-Li (25°N, 121°E) during the period of February 2002–May 2004. Combined data indicate that 40–50% of total extinction in the column air contributed by aerosols in 1–5km. Seasonally, spring time extinction is higher than other seasons. However, the summer extinction is the highest below about 2km. Sources for aerosols are determined by using satellite imageries and back trajectories. Aerosols backscattering ratio and depolarization ratio are then categorized based on their sources. We found that the largest optical thickness is biomass burning aerosols originated in Southeast Asia. The aerosols generated from Northern China transported by the high-pressure system in spring are usually dust with depolarization ratios in the range of 0.1–0.3, but varying backscattering coefficients. The aerosols optical characteristics will be useful for future understanding about their environmental and climate effects.
Keywords: Lidar; Back trajectories; Depolarization; Dust; Biomass burning
Polycyclic aromatic hydrocarbons in ambient air in the Philippines derived from passive sampler with polyurethane foam disk by Evangeline C. Santiago; Mylene G. Cayetano (pp. 4138-4147).
Passive samplers with polyurethane disks (PUF) were applied in the determination of the concentration of polycyclic aromatic hydrocarbons (PAHs) in ambient air in six residential areas in the Philippines during four simultaneous sampling periods. The uptake profiles of PAHs were determined at one site during one sampling period. Most of the PAHs that were detected in air at concentrations that were significantly higher than their analytical detection limits exhibited a linear uptake trend on the PUF disk. The linear uptake profiles of some high molecular weight (HMW) PAHs were not established and this is attributed to the low concentration of the compounds in air in the gaseous phase. The retention concentrations of phenanthrene-d-10 were determined after depuration in four sampling sites during two sampling periods. The sampling rate for phenanthrene-d-10 was calculated at the linear phase of the uptake using the kA derived from depuration experiments and the relationship of kA and sampling rate which was established in a previous passive sampling study. The average sampling rate obtained for phenanthrene d-10 (2.94±0.69m3d−1) was applied for derivation of the concentrations of the PAHs in the field samples.The passive sampler with PUF disk and short integration time of 42–56 days is applicable for the derivation of the concentrations of PAHs in ambient air in the Philippines. The concentrations of the organic pollutants derived from the passive sampler showed variability for the six residential areas; reflecting the influence of possible sources of emission of the pollutants at the sites at the different sampling periods. The weather conditions, including the occurrence of a tropical cyclone, increased rainfall and high-relative humidity during the rainy season, had an influence on the concentrations of PAHs derived by the passive sampler.
Keywords: Passive air sampling; Polycyclic aromatic hydrocarbons; Polyurethane foam disk
Compilation of a database on the composition of anthropogenic VOC emissions for atmospheric modeling in Europe by J. Theloke; R. Friedrich (pp. 4148-4160).
To analyse and generate air pollution control strategies and policies, e.g. efficient abatement strategies or action plans that lead to a fulfilment of air quality aims, atmospheric dispersion models (CTMs) have to be used. These models include a chemical model, where the numerous volatile organic compounds (VOCs) species are lumped together in classes. On the other hand, emission inventories usually report only total non-methane VOC (NMVOC), but not a subdivision into these classes. Thus, VOC species profiles are needed that resolve total NMVOC emission data. The objective of this publication is to present the results of a compilation of VOC species profiles that dissolve total VOC into single-species profiles for all relevant anthropogenic emission source categories and the European situation. As in atmospheric dispersion models usually modules for generating biogenic emissions are directly included, only anthropogenic emissions are addressed. VOC species profiles for 87 emission source categories have been developed. The underlying data base can be used to generate the data for all chemical mechanisms. The species profiles have been generated using recent measurements and studies on VOC species resolution and thus represent the current state of knowledge in this area. The results can be used to create input data for atmospheric dispersion models in Europe.The profiles, especially those for solvent use, still show large uncertainties. There is still an enormous need for further measurements to achieve an improved species resolution. In addition, the solvent use directive and the DECOPAINT directive of the European Commission will result in a change of the composition of paints; more water-based and high-solid paints will be used; thus the species resolution will change drastically in the next years. Of course, the species resolution for combustion and production processes also requires further improvement.
Keywords: VOC species profiles; Atmospheric modeling; CTM; Anthropogenic emissions; Traffic; Solvent use; Combustion processes; Production processes
Corrigendum to “Atmospheric speciation of mercury in two contrasting Southeastern US airsheds”
by Mark C. Gabriel; Derek G. Williamson; Steve Brooks (pp. 4161-4161).
Erratum to “Description of pollutant dispersion in an urban street canyon using two-dimensional lattice model”
by Jimenez-Hornero F.J. Jiménez-Hornero; Giraldez J.V. Giráldez; Gutierrez de Rave E. Gutiérrez de Ravé; F.J. Moral (pp. 4162-4162).