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Atmospheric Environment (v.40, #36)

Editorial board (pp. i).

Kinetics of the reaction between OH radicals and monochlorodimethylsulphide (CH3SCH2Cl) by Dudley E. Shallcross; Stewart Vaughan; David R. Trease; Carlos E. Canosa-Mas; Mariana V. Ghosh; John M. Dyke; Richard P. Wayne (pp. 6899-6904).
The gas-phase rate coefficient for the reaction between OH radicals and CH3SCH2Cl (MCDMS) was determined to be (2.5±1.3)×10−12cm3molecule−1s−1 using the discharge–flow kinetic technique. An estimate of ≈10−10cm3 molecule−1s−1 was obtained for the rate coefficient for reaction of Cl with MCDMS.It would appear that the reaction with OH is not the main loss process for CH3SCH2Cl in the marine boundary layer. The possible implications for the MBL of halogen-promoted oxidation of dimethylsulphide are considered.

Keywords: Marine boundary layer (MBL); Dimethylsulphide (DMS); Hydroxyl radical (OH); Atomic chlorine (Cl); Kinetics; Lifetime


Effects of particulate matter from gasoline and diesel vehicle exhaust emissions on silicate stones sulfation by Simao J. Simão; E. Ruiz-Agudo; C. Rodriguez-Navarro (pp. 6905-6917).
The effects of particulate matter (PM) from diesel and leaded gasoline motor vehicles exhaust emissions on sulfation of granites, syenite and gabbro stones have been experimentally studied. Abundant gypsum crystals and corrosion features developed on stones covered with diesel PM (DPM) following 72h exposure to 100ppm SO2 at a relative humidity of 100%. In contrast, very small amounts of gypsum were observed on stones covered with gasoline PM (GPM), while no effect was observed on naked control stones. Abundant elemental C and Fe-rich particles in DPM play a critical role in the catalytic oxidation of SO2 and the formation of H2SO4, which is responsible for silicate stone sulfation. Conversely, organic C and Pb-rich particles that are main components of GPM, do not play a significant role in sulfation. The response of each stone type towards sulfation is related to the stability of their constituent silicate minerals towards acid attack. Thus, the stones most susceptible to sulfation are those including nepheline (syenite), olivine, and pyroxene (gabbro), while granites in general, are most resistant to sulfation-related chemical weathering. These results help to explain how black (gypsum) crusts develop on silicate stones, and support limitations for (diesel) vehicular traffic and emission loads in urban centers.

Keywords: Black crusts; Gypsum; Silicate stones; Sulfation; C particles; Diesel PM


Modeling particle deposition onto rough walls in ventilation duct by Bin Zhao; Jun Wu (pp. 6918-6927).
An improved Eulerian model is proposed to predict particle deposition velocity onto rough walls in fully developed turbulent duct flow. The model treats the turbulent flow over rough walls as three different regimes of turbulent boundary layer (hydraulically smooth, transition and completely rough) according to the value of roughness Reynolds number (or called dimensionless roughness), k+. For each regime, the velocity and concentration boundary layer has a different thickness compared to that of the separated free shear layer, as flow separation behind the roughness is different, and this results in different shifted distance of virtual origin of velocity boundary layer. Thus a fitted equation is proposed based on measured data to estimate the shifted distance of velocity boundary layer for different values of k+, when calculating particle deposition velocity onto rough walls. Besides, as a successive study of previous one by the authors, the model also accounts for turbophoresis as well as Brownian diffusion, turbulent diffusion and gravitational settling. Turbophoretic velocity is calculated by employing a function of dimensionless normal distances in boundary layer to the duct walls. It only needs the friction velocity as the input. The predicted results agree well with published measured data for rough walls in most cases, and also agree better with measurement in ventilation ducts than those using the existing model.

Keywords: Aerosol; Particle; Deposition; Ventilation duct; Indoor air quality (IAQ); Rough wall


Potential of the cryoplane technology to reduce aircraft climate impact: A state-of-the-art assessment by Michael Ponater; Susanne Pechtl; Robert Sausen; Ulrich Schumann; Gerhard Hüttig (pp. 6928-6944).
The potential reduction in climate impact due to a switch from kerosene supported aviation to liquid hydrogen (LH2) supported aviation (cryoplanes) is assessed. Different scenarios for a respective gradual technology transition between 2015 and 2050 are provided. State-of-the-art simulations of three-dimensional (3D) radiative forcing (RF) distributions are compiled and complemented for the various agents determining aviation climate impact. They are utilized to quantify the globally averaged transient climate response and respective differences between the transition scenarios. A climate impact reduction of between 15% and 50% in terms of RF is indicated for the cryoplane scenarios at the 2050 time slice, with a best estimate near 30% in case of a swift transition. The respective reduction range is between 5% and 15% in terms of surface temperature change, with a best estimate of about 10%. The environmental benefit of a cryoplane transition further increases if time horizons beyond 2050 are considered. Besides known uncertainties in quantifying aviation climate impacts, crucial limitations of our assessment are insufficient knowledge on contrail cirrus induced by cryoplanes and on the feasibility to produce large amounts of LH2 from renewable energy sources.

Keywords: Aircraft climate impact; Alternative fuels; Technology transition


Atmospheric levels and cytotoxicity of PAHs and heavy metals in TSP and PM2.5 at an electronic waste recycling site in southeast China by W.J. Deng; P.K.K. Louie; W.K. Liu; X.H. Bi; J.M. Fu; M.H. Wong (pp. 6945-6955).
Twenty-nine air samples of total suspended particles (TSP, particles less than 30–60μm) and thirty samples of particles with aerodynamic diameter smaller than 2.5μm (PM2.5) were collected at Guiyu, an electronic waste (e-waste) recycling site in southeast China from 16 August 2004 to 17 September 2004. The results showed that mass concentrations contained in TSP and PM2.5 were 124±44.1 and 62.12±20.5μgm−3, respectively. The total sum of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) associated with TSP and PM2.5 ranged from 40.0 to 347 and 22.7 to 263ngm−3, respectively. Five-ring and six-ring PAHs accounted for 73% of total PAHs. The average concentration of benzo(a) pyrene was 2–6 times higher than in other Asian cities. Concentrations of Cr, Cu and Zn in PM2.5 of Guiyu were 4–33 times higher than in other Asian countries. In general, there were significant correlations between concentrations of individual contaminants in TSP with PM2.5 (i.e. PAHs, Cd, Cr, Cu, Pb, Zn, Mn except Ni and As). The high concentrations of both PAHs and heavy metals in air of Guiyu may impose a serious environmental and health concern. Cytotoxicity of the extract of TSP and PM2.5 of ten 24h samples collected against human promonocytic leukemia cell line U937 (ATCC 1593.2) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assay. The results showed that under the same concentrations of extract, PM2.5 cytotoxicity was 2–4 times higher than TSP.

Keywords: Electronic waste (E-waste); Polycyclic aromatic hydrocarbons (PAHs); Heavy metals; Cytotoxicity; MTT assay


Polycyclic aromatic hydrocarbons in dust from computers: one possible indoor source of human exposure by Yu Ren; Tiantao Cheng; Jianmin Chen (pp. 6956-6965).
Computer is an important part of our usual life and work. The harmful exposure to the radiation of computers has been paid attention broadly. However, chemical pollution related to computers is rarely reported. Here we investigated the levels and sources of EPA 16 priority polycyclic aromatic hydrocarbons (PAHs) in dust samples collected from components and internal walls of computers’ boxes (in-computers) in Shanghai, China. Dust samples were collected from 27 computers in different indoor environment: offices, laboratories, and one net bar. The levels of PAHs in dust samples were from 8.22μgg−1 to 42.04μgg−1. BbF, BgP, DbA, Chry and BaP were the most abundant PAHs. The levels of PAHs in computers in smoking rooms (mainly in the net bar) were usually 1.35–2.87 times higher than those in nonsmoking rooms, indicating that the indoor environment of different rooms affected the loading of dust PAHs significantly. To study the source of PAHs in computers, six dust samples were collected from windowsills (out-computers) in the corresponding rooms. The results indicated that most PAHs from in-computers were greater than those from out-computers, which indicated that parts of PAHs in computers may be emitted from the heated plastic material out of chips in computers when they are running, and be adsorbed on dust deposited on these components. The potential exposure of PAHs from computers was also evaluated, and our results showed that people maybe exposure particle-phase PAHs up to 2.99ngm−3 which are just sprayed out with dust from computers.

Keywords: Computer; Dust; Indoor; PAHs; Source


European emissions of mercury derived from long-term observations at Mace Head, on the western Irish coast by F. Slemr; R. Ebinghaus; P.G. Simmonds; S.G. Jennings (pp. 6966-6974).
Many emission inventories for mercury have been compiled but rarely constrained using observations of ambient air concentrations with a known quality. In this paper, we derive Hg/CO, Hg/halocarbon, and Hg/CH4 emission ratios from pollution episodes observed during the long-term mercury monitoring at the Mace Head Atmospheric Research Station in Ireland. The average Hg/CO emission ratio from 15 pollution episodes with air originating from the European continent observed between 1996 and 2003 was 0.0050±0.0021ngm−3ppbv−1, i.e. (5.5±2.3)×10−7mol/mol, which is almost identical to the ratio reported recently for the continental plumes of eastern Asia. Mercury correlated also with CFCl3 (CFC-11), CF2Cl2 (CFC-12), CH3CCl3, CCl4, CCl2FCF2Cl (CFC-113), CHCl3, N2O, and CH4 during the pollution episodes. The mercury emissions calculated from the emission ratios and the European emissions of the above gases are in reasonable agreement with the estimated anthropogenic total mercury emissions of 250t/yr in 1995. However, the measurements encompass almost exclusively elemental mercury whose anthropogenic emissions are estimated to be only 152tyr−1. Several hypotheses are proposed to explain this discrepancy, such as natural sources, underestimation of the emissions of elementary mercury, and erroneous speciation of anthropogenic emissions.

Keywords: Mercury; Emission; CO; Halocarbons; Inventory


GOME aerosol optical depth retrieval over ocean: Correcting for the effects of residual cloud contamination by Elisa Carboni (pp. 6975-6987).
Aerosol optical depths (AODs) retrieved from GOME reflectances using a clear sky algorithm have been compared to AODs from ground-based sunphotometers. A systematic overestimation of GOME AOD was found, mainly due to the presence of clouds within the GOME field-of-view. In order to take the influence of clouds into account, a model which assumes a linear dependence of AOD on cloud fraction has been tested. This model was validated using independent measurements from different AERONET sites. The monthly averaged maps of corrected AOD show similar spatial behaviour to AVHRR and TOMS maps. The method proposed here produces monthly maps of AOD from GOME data. It is applicable on a statistical analysis (monthly) and is proved to be effective in regions with high AOD, but relatively large uncertainties remain for background marine conditions.

Keywords: Aerosol optical depth; Remote sensing; GOME data; AERONET sunphotometer; Earth observation


Physicochemical and redox characteristics of particulate matter (PM) emitted from gasoline and diesel passenger cars by Michael D. Geller; Leonidas Ntziachristos; Athanasios Mamakos; Zissis Samaras; Debra A. Schmitz; John R. Froines; Constantinos Sioutas (pp. 6988-7004).
Particulate matter (PM) originating from mobile sources has been linked to a myriad of adverse health outcomes, ranging from cancer to cardiopulmonary disease, and an array of environmental problems, including global warming and acid rain. Till date, however, it is not clear which physical characteristics or chemical constituents of PM are significant contributors to the magnitude of the health risk. This study sought to determine the relationship between physical and chemical characteristics of PM while quantitatively measuring samples for redox activity of diesel and gasoline particulate emissions from passenger vehicles typically in use in Europe. The main objective was to relate PM chemistry to the redox activity in relation to vehicle type and driving cycle. Our results showed a high degree of correlation between several PM species, including elemental and organic carbon, low molecular weight polycyclic aromatic hydrocarbons, and trace metals such as lithium, beryllium, nickel and zinc, and the redox activity of PM, as measured by a quantitative chemical assay, the dithiothreitol (DTT) assay. The reduction in PM mass or number emission factors resulting from the various engine configurations, fuel types and/or after-treatment technologies, however, was non-linearly related to the decrease in overall PM redox activity. While the PM mass emission rate from the diesel particle filter (DPF)-equipped vehicle was on average approximately 25 times lower than that of the conventional diesel, the redox potential was only eight times lower, which makes the per mass PM redox potential of the DPF vehicle about three times higher. Thus, a strategy aimed at protecting public health and welfare by reducing total vehicle mass and number emissions may not fully achieve the desired goal of preventing the health consequences of PM exposure. Further, study of the chemical composition and interactions between various chemical species may yield greater insights into the toxicity of the PM content of vehicle exhaust.

Keywords: Diesel; Gasoline; Ultrafine particles; Redox activity


Characterization and evaluation of smoke tracers in PM: Results from the 2003 Montana wildfire season by Tony J. Ward; Raymond F. Hamilton Jr; Roy W. Dixon; Michael Paulsen; Christopher D. Simpson (pp. 7005-7017).
Throughout August and September 2003, Missoula, Montana was heavily impacted by smoke from wildland forest fires burning throughout western Montana. In an effort to study the organic compounds contributing to smoke particulate matter impacting downwind communities, three co-located PM2.5 cyclones collected 24-h samples during significant smoke events in Missoula. Filter samples were then analyzed at two independent laboratories to quantify the concentrations of several chemical markers of wood smoke generated under natural combustion conditions, as well as to provide an intercomparison study of analytical methods (HPLC and GC/MS) used in the determination of levoglucosan concentrations.Concentrations of monosaccharide anhydrides, methoxyphenols and soluble potassium were measured from PM2.5 samples collected during periods of smoke and baseline (non-impacted) conditions. From these analyses, the associations between the wood smoke markers and PM2.5 mass were examined. Levoglucosan was found to be the most useful marker for wood smoke generated from natural forest fire events in the northern Rocky Mountains, whereas measurement of other species (mannosan, methoxyphenols) provided information on the type of vegetative material burned (e.g., hardwood versus softwood). The emission ratios of levoglucosan to PM2.5 and organic carbon from the wildfire smoke was found to be 0.042 and 0.062, respectively. Results of the statistical analyses showed that the GC/MS and HPLC approaches to levoglucosan analysis were statistically equivalent.

Keywords: PM; 2.5; Smoke; Wildland forest fire; Chemical tracers; Levoglucosan


Seasonal variations in SO2 plume transport over Japan: Observations at the summit of Mt. Fuji from winter to summer by Yasuhito Igarashi; Yosuke Sawa; Katsuhiro Yoshioka; Hiroshi Takahashi; Hidekazu Matsueda; Yukiko Dokiya (pp. 7018-7033).
We undertook continuous measurements of SO2 concentrations at the summit of Mt. Fuji, Japan (3776m above sea level), during the period January to July, 2004. These data include the first data set that fills the previous gap in SO2 time series for the springtime middle troposphere over Japan. The time series shows trends in high-SO2 long-range transport events from winter to spring. Elevated SO2 concentrations are always accompanied by elevated CO and222Rn concentrations, and backward trajectories for such events indicate a continental origin. These data display clear sporadic signatures of Asian outflow over Japan to the North Pacific. Such high-SO2 events decline in strength and frequency during spring. The observed seasonal variation of SO2 events may in fact have nothing to do with seasonality in SO2 emissions from the Asian continent, as seasonal patterns in SO2 events show a similar phase shift to that of the prevailing wind direction and relative humidity (RH) observed on-site. The changes in air mass indicated by daily backward trajectory analysis may also explain the observed temporal changes in SO2 events. A major factor appears to be the removal of SO2 from the continental pollution plume during long-range transport. The SO2-bearing polluted air is dry during the depths of winter; accordingly, little SO2 is removed by cloud processes at this time of year. The nature of the air mass changes during spring when increasing humidity levels lead to the increased removal of SO2 by cloud processes. RH data along the air mass travel path also support the importance of cloud processes in reducing SO2 concentrations within the pollution plume.

Keywords: SO; 2; Seasonal variation; Asian outflow; Relative humidity; Cloud processes; Free troposphere


Particulate matter composition and emission rates from the disk incorporation of class B biosolids into soil by Paez-Rubio Tania Paez-Rubio; Xin Hua; James Anderson; Jordan Peccia (pp. 7034-7045).
Biosolids contain metal, synthetic organic compound, endotoxin, and pathogen concentrations that are greater than concentrations in the agricultural soils to which they are applied. Once applied, biosolids are incorporated into soils by disking and the aerosols produced during this process may pose an airborne toxicological and infectious health hazard to biosolids workers and nearby residents. Field studies at a Central Arizona biosolids land application site were conducted to characterize the physical, chemical, and biological content of the aerosols produced during biosolids disking and the content of bulk biosolids and soils from which the aerosols emanate. Arrayed samplers were used to estimate the vertical source aerosol concentration profile to enable plume height and associated source emission rate calculations. Source aerosol concentrations and calculated emission rates reveal that disking is a substantial source of biosolids-derived aerosols. The biosolids emission rate during disking ranged from 9.91 to 27.25mgs−1 and was greater than previously measured emission rates produced during the spreading of dewatered biosolids or the spraying of liquid biosolids. Adding biosolids to dry soils increased the moisture content and reduced the total PM10 emissions produced during disking by at least three times. The combination of bulk biosolids and aerosol measurements along with PM10 concentrations provides a framework for estimating aerosol concentrations and emission rates by reconstruction. This framework serves to eliminate the difficulty and inherent limitations associated with monitoring low aerosol concentrations of toxic compounds and pathogens, and can promote an increased understanding of the associated biosolids aerosol health risks to workers and nearby residents.

Keywords: Biosolids; Sewage sludge; Bioaerosols; Fugitive dust; Endotoxin


Conversion of metam sodium and emission of fumigant from soil columns by Wei Zheng; Scott R. Yates; Sharon K. Papiernik; Joe Nunez (pp. 7046-7056).
Metam sodium is the most widely used soil fumigant in the United States. The primary breakdown product of metam sodium in soil is methyl isothiocyanate (MITC), an active pesticidal agent with a high toxicity and a great potential for volatilization. Reducing atmospheric emissions of MITC is therefore critical to maintain air quality. The objective of this study was to examine the rate and efficiency of conversion of metam sodium to MITC in soil and to investigate the potential of using surface water sealing to reduce MITC emissions. The conversion of metam sodium to MITC was a rapid abiotic decomposition process. At typical field application rates, the conversion efficiency depended on the initial content of metam sodium in soil, but was independent of soil moisture, soil type, and soil atmospheric conditions. A soil column system was used to measure the emission and distribution of MITC after subsurface and surface application of metam sodium. Volatilization flux and cumulative emission loss of MITC was substantially reduced with surface water sealing compared to uncovered soil columns after subsurface application of metam sodium. When metam sodium was surface applied in simulated chemigation, surface water sealing was ineffective, suggesting the need for additional emissions reduction practices when metam sodium is broadcast. Overall, the results of the column experiment indicate that surface water sealing with subsurface application of metam sodium may be an effective and economical strategy to reduce MITC emissions while maintaining pest control efficacy.

Keywords: Metam sodium; MITC; Fumigant; Conversion; Surface water sealing; Emission reductionAbbreviations; MITC; methyl isothiocyanate; GC; gas chromatography; NPD; nitrogen–phosphorus detector


Characteristics of carbonyl compounds emission from a diesel-engine using biodiesel–ethanol–diesel as fuel by Xiaobing Pang; Xiaoyan Shi; Yujing Mu; Hong He; Shijin Shuai; Hu Chen; Rulong Li (pp. 7057-7065).
Characteristics of carbonyl compounds (carbonyls) emissions from biodiesel–ethanol–diesel (BE–diesel) were investigated in a Commins-4B diesel engine and compared with those from fossil diesel. Acetaldehyde was the most abundant carbonyls in the exhaust, followed by formaldehyde, acetone, propionaldehyde and benzaldehyde. Apliphatic carbonyls emitted from BE–diesel were higher than those from diesel fuel, while formaldehyde and aromatic carbonyls were less than those from diesel fuel. Total carbonyls emissions from BE–diesel were 1–12% higher than those from diesel fuel depending on engine operating conditions. The effects of engine speed and load level were also investigated carefully. It was found that total carbonyls emission was in positive correlation with the engine speed. During the constant speed/varying load tests, minimum total carbonyls emission was found at 50% load. Compared with fossil diesel, the BE-diesel was observed to significantly reduce PM emission and increase slightly NO x emission.

Keywords: Carbonyl compounds; Biodiesel; Ethanol; Diesel


Evaluation of SO2 pollution levels between four different types of air quality monitoring stations by Hang Thi Nguyen; K.-H. Ki-Hyun Kim (pp. 7066-7081).
In order to assess the spatiotemporal distribution patterns of sulfur dioxide (SO2), its concentration data sets measured from four different types of air quality monitoring (AQM) stations in Korea were analyzed for the period 1998–2003. The target AQM stations were selected to represent both highly urbanized locations in seven major cities (i.e., urban traffic (A) and urban background (B)) and relatively remote locations in nine major provinces (suburban background (C) and rural background (D)) in Korea. As such, the mean concentrations of SO2 were clearly distinguished both between the A- and B-type stations and between the C- and D-type stations. The mean concentration levels of SO2 in the A-type stations were approximately 18% higher than those of the B-type stations; it was found that the concentration of the former ranged from 7.94ppb (Seoul) to 14.2ppb (Ulsan), and the latter from 5.43ppb (Gwangju) to 12.8ppb (Ulsan). Likewise, there were many distinctions between the C-and D-type stations. The mean concentrations of the C-type stations varied from 3.88ppb (Jeju) to 8.50ppb (Jeonnam), while those of the D-type stations from 1.47ppb (Jeju) to 4.76ppb (Gangwon). Comparison of seasonal patterns indicated that the SO2 values tend to peak consistently during the winter (or spring) months, regardless of station types. When the SO2 data were compared on a long-term basis throughout the whole study period, the patterns generally exhibited a gradual and systematic decrease for most study sites. However, the patterns for such annual changes tended to differ between major urban (A and B) and suburban station pairs (C and D). It was found that such decreasing trends were more clear in the former pair than in the latter. The overall results of our analysis from diverse AQM station types indicate that the distribution characteristics of SO2 may have been controlled rather sensitively through time by social and environmental changes which forced the reduction of SO2 emissions.

Keywords: Sulfur dioxide; Ambient; Roadside; Background; Korea


Accumulation histories of magnetic particles on pine needles as function of air quality by E. Lehndorff; M. Urbat; L. Schwark (pp. 7082-7096).
Atmospheric particulates, especially in the PM2.5 range, pose a significant threat to human health and require adequate regulation and monitoring. Biomonitoring offers a suitable means to investigate air quality at high temporal and spatial resolution. The accumulation histories of magnetic particulates in the PM0.1–PM10 class for 6 sites of different emission background in the Cologne Conurbation, NW-Germany, are described. Five needle cohorts were sampled in triplicate in winter and summer of 2004 for determination of magnetic properties ( χ, IRM and ARM). Variability between sites was found to be significantly higher than within sites. Investigated accumulation rates predominantly reflect anthropogenic emissions. Natural processes are of minor importance, comprising canopy effects and abrasive removal of particles. Emission specific concentrations and grain size distributions can be detected by combination of enviromagnetic parameters and allow for source allocation in highly resolved spatial data sets. For source identification, SEM and Microprobe analyses differentiate fine and coarse PM according to shape and element content. Microscopic analyses are limited with respect to assessment of most health-adverse ultrafine PM, which can be characterised in detail for composition and grain size by enviromagnetic techniques.

Keywords: Enviromagnetics; Environmental magnetism; Biomonitoring; Particle size; Magnetic properties; Susceptibility; Air quality
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