Atmospheric Environment (v.83, #C)
Editorial board (i).
Pathological study of the prevalence of silicosis among coal miners in Iran: A case history by Masoud Zare Naghadehi; Farhang Sereshki; F. Mohammadi (1-5).
One of the most hazardous diseases that is commonly associated with the coal mining industry is Silicosis which caused by dust inhalation. This disease occurs as a result of prolonged breathing of dust containing silica (quartz). The generation of coal mine dust during underground and surface coal mining is the most significant source of coal dust exposure. Silica dust develops scar tissue inside the lungs which reduces the lungs ability to extract oxygen from the air. All miners working in underground and surface coal mines are at risk of being exposed to mine dust containing silica. In this study, cases with pathologic diagnosis of silicosis during seven years period between 2000 and 2007 were retrieved, from the pathologic file of Department of Pathology, Massih Daneshvary Hospital in Iran. Results of this case study showed the great effects of dust exposure and inhalation from the viewpoint of symptoms especially between the miners.
Keywords: Silicosis; Coal miners; Lung diseases; Pathology; Environmental pollution;
Variability of intra-urban exposure to particulate matter and CO from Asian-type community pollution sources by Shih-Chun Candice Lung; Pao-Kuei Hsiao; Tzu-Yao Wen; Chun-Hu Liu; Chi Betsy Fu; Yu-Ting Cheng (6-13).
Asian residential communities are usually dotted with various spot pollution sources (SPS), such as restaurants, temples, and home factories, with traffic arteries passing through, resulting in higher intra-urban pollution variability compared with their western counterparts. Thus, it is important to characterize spatial variability of pollutant levels in order to assess accurately residents' exposures in their communities. The objectives of this study are to assess the actual pollutant levels and variability within an Asian urban area and to evaluate the influence of vehicle emission and various SPS on the exposure levels within communities. Real-time monitoring was conducted for a total of 123 locations for particulate matter (PM) and CO in Taipei metropolitan, Taiwan. The mean concentrations for PM1, PM2.5, PM10, and CO are 29.8 ± 22.7, 36.0 ± 25.5, 61.9 ± 35.0 μg m−3 and 4.0 ± 2.5 ppm, respectively. The mean values of PM1/PM2.5 and PM2.5/PM10 are 0.80 ± 0.10 and 0.57 ± 0.15, respectively. PM and CO levels at locations near SPS could be increased by 3.5–4.9 times compared with those at background locations. Regression results show that restaurants contribute significantly 6.18, 6.33, 7.27 μg m−3, and 1.64 ppm to community PM1, PM2.5, PM10, and CO levels, respectively; while the contribution from temples are 13.2, 15.1, and 17.2 μg m−3 for PM1, PM2.5 and PM10, respectively. Additionally, construction sites elevate nearby PM10 levels by 14.2 μg m−3. At bus stops and intersections, vehicle emissions increased PM1 and PM2.5 levels by 5 μg m−3. These results demonstrate significant contribution of community sources to air pollution, and thus the importance of assessing intra-community variability in Asian cities for air pollution and health studies. The methodology used is applicable to other Asian countries with similar features.
Keywords: Community air pollution; Aerosol size distribution; Traffic emission; Asian cooking emission; Temple emission;
Chemical compositions and reconstructed light extinction coefficients of particulate matter in a mega-city in the western Yangtze River Delta, China by Guofeng Shen; Miao Xue; Siyu Yuan; Jie Zhang; Qiuyue Zhao; Bing Li; Haisuo Wu; Aijun Ding (14-20).
Ambient particulate matter was collected in a megacity, Nanjing in western YRD during the spring and summer periods. Chemical compositions of fine PM including organic carbon, elemental carbon, elements and water soluble ions were analyzed. The light extinction coefficients were reconstructed following the IMPROVE formula. Organic matter was the most abundant composition in PM2.5 (20–25% of total mass), followed by the inorganic ions. During the spring time, geological materials contributed 25% of the total PM2.5. Estimated light extinction coefficient ranged from 133 to 560 Mm−1 with the deciview haze index value of 26–40 dv, indicating strong light extinction by PM and subsequently low visibility in the city. Reconstructed ammonium sulfate, ammonium nitrate, organic matter and light absorption carbon in fine PM contributed significantly (37 ± 10, 16 ± 6, 15 ± 4 and 10 ± 3%, respectively) to the total light extinction of PM, while soil (5–7%) and sea salt fractions (2–4%) in fine PM and coarse PM (6–11%) had relatively minor influences. The results of backward air trajectory showed that the site was strongly influenced by the air from the eastern (39%) and southeastern (29%) areas during the sampling period. Air plumes from the Southeastern had both high PM mass pollution and large light extinction, while the air mass originating from the Northwestern resulted in high PM mass loading but relatively lower light extinction.
Keywords: Chemical composition; Reconstructed light extinction coefficient; Deciview index; Backward air trajectory; Western YRD region;
Particulate matter analysis in indoor environments of urban and rural primary schools using passive sampling methodology by Nuno Canha; Susana Marta Almeida; Maria do Carmo Freitas; Maria Trancoso; Ana Sousa; Filomena Mouro; Hubert Th. Wolterbeek (21-34).
Passive sampling methodology was applied to collect particulate matter (PM) in classrooms of urban and rural primary schools. The samples were taken during a year by passive deposition allowing the study of seasonal variability of the particles masses and chemical content. Chemical characterization of the collected particles was performed in order to measure its soluble ions content and elemental composition. To identify the main polluting sources, correlations between parameters and enrichment factors were studied. Higher particle masses concentrations were registered in autumn, with a mean of 1.54 ± 0.74 μg day−1 cm−2. The major element in the collected particles was calcium, representing 63–73% of the analyzed mass of the particles inside the urban classrooms. In the rural cluster, calcium remained the major component but with a slight lower contribution to the overall particles composition (42–46%). The calcium source was hypothesized to be the chalk used in the blackboards of the classrooms due to a strong correlation found between Ca2+ and SO4 2−. Soil re-suspension, traffic and other anthropogenic emission sources were also identified. Analysis showed enrichment of the particles with Br, Ca, Zn and Sb in the urban cluster and enrichment of the same elements, except for Ca, in the rural cluster. The comparison between the results from both clusters allowed the identification of classrooms with higher particles concentrations that can indicate potential indoor air quality problems (reflected by an indoor accumulation of pollutants).
Keywords: Indoor air quality; Primary schools; Particulate matter; Passive method; Source apportionment; Enrichment factors;
Measurement of the oxidative potential of PM2.5 and its constituents: The effect of extraction solvent and filter type by Aileen Yang; Aleksandra Jedynska; Bryan Hellack; Ingeborg Kooter; Gerard Hoek; Bert Brunekreef; Thomas A.J. Kuhlbusch; Flemming R. Cassee; Nicole A.H. Janssen (35-42).
The capacity of Particulate Matter (PM) to oxidise target molecules, defined as its oxidative potential (OP), has been proposed as a biologically more relevant metric than PM mass. Different assays exist for measuring OP and their methodologies vary in the choice of extraction solvent and filter type. Little is known about the impact of extraction and filter type on reported OP. Four a-cellular assays; electron spin resonance (ESR), dithiothreitol (DTT), ascorbate acid depletion (AA) and reductive acridinium triggering (CRAT) assay were chosen to evaluate whether these differences affect the OP measurement, the correlation between OP from different assays and the association with PM chemical composition. We analysed 15 urban 48–72 h PM2.5 samples collected on quartz and Teflon filters. The choice of extraction solvent had only a significant effect on OPDTT, while all OP measures for quartz filters were heavily attenuated. OP values derived from quartz were, however, highly correlated with those derived from Teflon. OPDTT correlated highly with OPCRAT, and OPESR correlated highly with OPAA. These correlations were affected by the choice of filter type. Correlations between OP and PM chemical composition were not affected by filter type and extraction solvent. These findings indicate that the measurement of relative OP reactivity is not greatly influenced by filter type and extraction solvent for the investigated assays. This robustness is also promising for exploratory use in monitoring and subsequent epidemiological studies.
Keywords: Oxidative potential; DTT; ESR; Ascorbate acid depletion; Reactive oxygen species; Particulate matter;
Optical properties and radiative forcing of urban aerosols in Nanjing, China by B.L. Zhuang; T.J. Wang; S. Li; J. Liu; R. Talbot; H.T. Mao; X.Q. Yang; C.B. Fu; C.Q. Yin; J.L. Zhu; H.Z. Che; X.Y. Zhang (43-52).
Continuous measurements of atmospheric aerosols were made in Nanjing, a megacity in China, from 18 January to 18 April, 2011 (Phase 1) and from 22 April 2011 to 21 April 2012 (Phase 2). Aerosol characteristics, optical properties, and direct radiative forcing (DRF) were studied through interpretations of these measurements. We found that during Phase 1, mean PM2.5, black carbon (BC), and aerosol scattering coefficient (Bsp) in Nanjing were 76.1 ± 59.3 μg m−3, 4.1 ± 2.2 μg m−3, and 170.9 ± 105.8 M m−1, respectively. High pollution episodes occurred during Spring and Lantern Festivals when hourly PM2.5 concentrations reached 440 μg m−3, possibly due to significant discharge of fireworks. Temporal variations of PM2.5, BC, and Bsp were similar to each other. It is estimated that inorganic scattering aerosols account for about 49 ± 8.6% of total aerosols while BC only accounted for 6.6 ± 2.9%, and nitrate was larger than sulfate. In Phase 2, optical properties of aerosols show great seasonality. High relative humidity (RH) in summer (June, July, August) likely attributed to large optical depth (AOD) and small Angstrom exponent (AE) of aerosols. Due to dust storms, AE of total aerosols was the smallest in spring (March, April, May). Annual mean 550-nm AOD and 675/440-nm AE were 0.6 ± 0.3 and 1.25 ± 0.29 for total aerosols, 0.04 ± 0.02 and 1.44 ± 0.50 for absorbing aerosols, 0.48 ± 0.29 and 1.64 ± 0.29 for fine aerosols, respectively. Annual single scattering albedo of aerosols ranged from 0.90 to 0.92. Real time wavelength-dependent surface albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to assess aerosol DRFs. Both total and absorbing aerosol DRFs had significant seasonal variations in Nanjing and they were the strongest in summer. Annual mean clear sky TOA DRF (including daytime and nighttime) of total and absorbing aerosols was about −6.9 and +4.5 W m−2, respectively. Aerosol DRFs were found to be sensitive to surface albedo. Over brighter surfaces, solar radiation was more absorbed by absorbing aerosols and less scattered by scattering aerosols.
Keywords: Aerosols; Optical depth; Single scattering albedo; Angstrom exponent; Radiative forcing; Nanjing;
Long-term measurement of terpenoid flux above a Larix kaempferi forest using a relaxed eddy accumulation method by Tomoki Mochizuki; Akira Tani; Yoshiyuki Takahashi; Nobuko Saigusa; Masahito Ueyama (53-61).
Terpenoids emitted from forests contribute to the formation of secondary organic aerosols and affect the carbon budgets of forest ecosystems. To investigate seasonal variation in terpenoid flux involved in the aerosol formation and carbon budget, we measured the terpenoid flux of a Larix kaempferi forest between May 2011 and May 2012 by using a relaxed eddy accumulation method. Isoprene was emitted from a fern plant species Dryopteris crassirhizoma on the forest floor and monoterpenes from the L. kaempferi. α-Pinene was the dominant compound, but seasonal variation of the monoterpene composition was observed. High isoprene and monoterpene fluxes were observed in July and August. The total monoterpene flux was dependent on temperature, but several unusual high positive fluxes were observed after rain fall events. We found a good correlation between total monoterpene flux and volumetric soil water content (r = 0.88), and used this correlation to estimate monoterpene flux after rain events and calculate annual terpenoid emissions. Annual carbon emission in the form of total monoterpenes plus isoprene was determined to be 0.93% of the net ecosystem exchange. If we do not consider the effect of rain fall, carbon emissions may be underestimated by about 50%. Our results suggest that moisture conditions in the forest soil is a key factor controlling the monoterpene emissions from the forest ecosystem.
Keywords: Isoprene; Monoterpene; Flux; Relaxed eddy accumulation method; Volumetric soil water content; Annual carbon budget;
Ragweed pollen source inventory for France – The second largest centre of Ambrosia in Europe by Michel Thibaudon; Branko Šikoparija; Gilles Oliver; Matt Smith; Carsten A. Skjøth (62-71).
France, in particular the Rhône-Alpes region, is one of the three main centres of ragweed (Ambrosia) in Europe. The aim of this study is to develop a gridded ragweed pollen source inventory for all of France that can be used in assessments, eradication plans and by atmospheric models for describing concentrations of airborne ragweed pollen. The inventory combines information about spatial variations in annual Ambrosia pollen counts, knowledge of ragweed ecology, detailed land cover information and a Digital Elevation Model. The ragweed inventory consists of a local infection level on a scale of 0–100% (where 100% is the highest plant abundance per area in the studied region) and a European infection level between 0% and 100% (where 100% relates to the highest identified plant abundance in Europe using the same methodology) that has been distributed onto the EMEP grid with 5 km × 5 km resolution. The results of this analysis showed that some of the highest mean annual ragweed pollen concentrations were recorded at Roussillon in the Rhône-Valley. This is reflected by the inventory, where the European infection level has been estimated to reach 67.70% of the most infected areas in Europe i.e. Kecskemét in central Hungary. The inventory shows that the Rhône Valley is the most heavily infected part of France. Central France is also infected, but northern and western parts of France are much less infected. The inventory can be entered into atmospheric transport models, in combination with other components such as a phenological model and a model for daily pollen release, in order to simulate the dispersion of ragweed pollen within France as well as potential long-distance transport from France to other European countries.Display Omitted
Keywords: Aeroallergens; Bioaerosols; Air quality; Emissions; Particles;
Characterisation of trace metals in atmospheric particles in the vicinity of iron and steelmaking industries in Australia by K. Mohiuddin; V. Strezov; P.F. Nelson; E. Stelcer (72-79).
The aims of this work are to provide a detailed physicochemical assessment of atmospheric particles collected in the vicinity of three iron and steelmaking plants and to indicate the importance of chemical characterisation of the particles, in addition to the assessment of the particle size and concentrations. In this study, atmospheric sampling sites were selected downstream of three iron and steel processing operations in Australia and one background site in an urban area with little industrial activity. The collected particles were analysed for a range of particle size mass concentrations and detailed chemical analysis of the trace metals Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn in the corresponding particle size ranges was carried out. The PM2.5 fractions in the PM10 particles at all sampling sites ranged from 35 to 62% indicating fine particles made a significant contribution to this size fraction at these sampling sites. Similarly, PM1 to the total PM10 at all sites varied from 20 to 46% and contributed significantly to the PM10 mass loading. When compared to the background sampling site, all detected metals in the particles collected near the iron and steelmaking operations had 3.4–14 times higher concentrations of PM10, PM2.5 and PM1. Iron (Fe) was found to be the dominant metal in the particles collected in vicinity of the iron and steel processing industries contributing up to 12% of the total particle mass loading. This study suggests that the metal composition of PM10, PM2.5 and PM1 varies significantly between sites and the associated metal exposure value is considerably higher in the vicinity of iron and steel processing industries than in the urban area for the same particle concentration level.
Keywords: PM10; PM2.5; PM1; Iron and steel industry; PIXE; Trace metal;
Observations of ammonia, nitric acid, and fine particles in a rural gas production region by Yi Li; Florian M. Schwandner; H. James Sewell; Angela Zivkovich; Mark Tigges; Suresh Raja; Stephen Holcomb; John V. Molenar; Lincoln Sherman; Cassie Archuleta; Taehyoung Lee; Jeffrey L. Collett (80-89).
Continuous measurements of the atmospheric trace gases ammonia (NH3) and nitric acid (HNO3) and of fine particle (PM2.5) ammonium (NH4 +), nitrate (NO3 −) and sulfate (SO4 2−) were conducted using a denuder/filter system from December 2006 to December 2011 at Boulder, Wyoming, a region of active gas production. The average five year concentrations of NH3, HNO3, NH4 +, NO3 − and SO4 2− were 0.17, 0.19, 0.26, 0.32, and 0.48 μg m−3, respectively. Significant seasonal patterns were observed. The concentration of NH3 was higher in the summer than in other seasons, consistent with increased NH3 emissions and a shift in the ammonium nitrate (NH4NO3) equilibrium toward the gas phase at higher temperatures. High HNO3 concentrations were observed both in the summer and the winter. Elevated wintertime HNO3 production appeared to be due to active local photochemistry in a shallow boundary layer over a reflective, snow-covered surface. PM2.5 NH4 + and SO4 2− concentrations peaked in summer while NO3 − concentrations peaked in winter. Cold winter temperatures drive the NH3–HNO3–NH4NO3 equilibrium toward particulate NH4NO3. A lack of NH3, however, frequently results in substantial residual gas phase HNO3 even under cold winter conditions.
Keywords: Ammonium; Nitrate; Gas/particle partitioning; Denuder; Wyoming;
VOC emissions from residential combustion of Southern and mid-European woods by Margarita Evtyugina; Célia Alves; Ana Calvo; Teresa Nunes; Luís Tarelho; Márcio Duarte; Sónia O. Prozil; Dmitry V. Evtuguin; Casimiro Pio (90-98).
Emissions of trace gases (carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbons (THC)), and volatile organic compounds (VOCs) from combustion of European beech, Pyrenean oak and black poplar in a domestic woodstove and fireplace were studied. These woods are widely used as biofuel in residential combustion in Southern and mid-European countries. VOCs in the flue gases were collected in Tedlar bags, concentrated in sorbent tubes and analysed by thermal desorption-gas chromatography–flame ionisation detection (GC–FID). CO2 emissions ranged from 1415 ± 136 to 1879 ± 29 g kg−1 (dry basis). The highest emission factors for CO and THC, 115.8 ± 11.7 and 95.6 24.7 ± 6.3 g kg−1 (dry basis), respectively, were obtained during the combustion of black poplar in the fireplace. European beech presented the lowest CO and THC emission factors for both burning appliances. Significant differences in emissions of VOCs were observed among wood species burnt and combustion devices. In general the highest emission factors were obtained from the combustion of Pyrenean oak in the woodstove. Among the VOCs identified, benzene and related compounds were always the most abundant group, followed by oxygenated compounds and aliphatic hydrocarbons. The amount and the composition of emitted VOCs were strongly affected by the wood composition, the type of burning device and operating conditions. Emission data obtained in this work are useful for modelling the impact of residential wood combustion on air quality and tropospheric ozone formation.
Keywords: Residential wood combustion; Emission factors; VOCs;
A simple semi-empirical technique for apportioning the impact of roadways on air quality in an urban neighbourhood by M.A. Elangasinghe; K.N. Dirks; N. Singhal; S.B. Costello; I. Longley; J.A. Salmond (99-108).
Air pollution from the transport sector has a marked effect on human health, so isolating the pollutant contribution from a roadway is important in understanding its impact on the local neighbourhood. This paper proposes a novel technique based on a semi-empirical air pollution model to quantify the impact from a roadway on the air quality of a local neighbourhood using ambient records of a single air pollution monitor. We demonstrate the proposed technique using a case study, in which we quantify the contribution from a major highway with respect to the local background concentration in Auckland, New Zealand. Comparing the diurnal variation of the model-separated background contribution with real measurements from a site upwind of the highway shows that the model estimates are reliable. Amongst all of the pollutants considered, the best estimations of the background were achieved for nitrogen oxides. Although the multi-pronged approach worked well for predominantly vehicle-related pollutants, it could not be used effectively to isolate emissions of PM10 due to the complex and less predictable influence of natural sources (such as marine aerosols).The proposed approach is useful in situations where ambient records from an upwind background station are not available (as required by other techniques) and is potentially transferable to situations such as intersections and arterial roads. Applying this technique to longer time series could help to understand the changes in pollutant concentrations from the road and background sources for different emission scenarios, for different years or seasons. Modelling results also show the potential of such a hybrid semi-empirical models to contribute to our understanding of the physical parameters determining air quality and to validate emissions inventory data.
Keywords: Urban air quality; Semi-empirical modelling; Highway; Background concentration;
Chemical characteristics of atmospheric fallout in the south of Xi'an during the dust episodes of 2001–2012 (NW China) by Xiaoping Li; Linna Feng; Chunchang Huang; Xiangyang Yan; Xu Zhang (109-118).
Atmospheric fallouts (AFs) were collected in the south of Xi'an, NW China, during the dust episodes of 2001–2012. The chemical characteristics of total 68 AF samples including their chemical compositions, size distribution and magnetic susceptibility were studied. The contamination degree and the source of heavy metals in AF were also explored with enrichment factor method and multivariate statistical analysis. The results showed that the particle mass size distribution of AFs dominated by coarse particles (PM10–50) in dust days. The concentrations of 26 elements associated with AFs determined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) in studied sites varied from 92.90 to 188.10 mg kg−1 for Cr, 31.40 and 63.00 mg kg−1 for Cu, 16.60 to 167.30 for Pb and 106.60 to 196.80 for Zn. Their average concentrations found in this study were 139.22 ± 29.41 mg kg−1, 46.93 ± 10.56 mg kg−1, 78.42 ± 46.52 mg kg−1 and 150.61 ± 32.84 mg kg−1, respectively, which exceeded their corresponding recommended background values more than two times. While, other elements, such as Br varied from 1.10 to 5.90 with 3.34 ± 1.60 mg kg−1 mean, Cs from 2.90 to 10.90 with mean of 7.23 ± 2.47 mg kg−1, Ga between 6.90 and 20.80 with 15.23 ± 3.59 mg kg−1, Rb in the range of 62.10–124.20 with the average of 80.69 ± 16.89 mg kg−1, Y from 9.90 to 35.00 with 20.43 ± 6.27 mg kg−1 average, La from 29.60 to 54.20 with mean of 37.28 ± 8.28 mg kg−1 and V with average of 81.97 ± 8.93 mg kg−1 in the 57.7–92.10 mg kg−1. Multivariate statistical analysis (principal component analysis and clustering analysis) was suggested that the principal element elements, Al, Fe, Si, K, Ca, Na, Mg, coupled with the trace elements Co, V, Ce, Mn, Ni, Ga, Y, Rb, La, Br, Cs were predominated by crustal material sources, whereas, Cr, Cu, Ba, Sr, As, Pb and Zn were highly influenced by anthropogenic activities. Simultaneously, the water-soluble ions (WS-ions) of NH4 +, SO4 2−, SO3 2−, NO3 −, SiO4 4−, HSO4 − contained in APs identified by FT-IR spectroscopy were possible originated from coal combustion. The results were also confirmed and consistent with the observations of magnetic susceptibility (MS), enrichment factor (EFs) and contamination evaluation analysis. With such rates of atmospheric fallouts that contain elevated levels of toxic elements during the dust storm condition, actions should be taken to continually examine and understand of the potential impacts of AFs on surface ecosystem, water resource, and human health in the dust storm condition.Atmospheric fallouts (AFs) were collected in the south of Xi'an, NW China, during the dust episodes of 2001–2012. The chemical compositions of AFs dominated by coarse particles (PM10-50), including of trace elements and water-soluble ions (WS-ions), were identified and quantified by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) and FTIR spectroscopy. The heavy metal hazards containing in AFs, for example, Cr, Cu, Ba, Sr, As, Pb and Zn were highly influenced by anthropogenic activities (e.g. traffic-related, non-ferrous metal industries, combustion of fuels, coal fly-ash sources). While, Al, Fe, Si, K, Ca, Na, Mg, coupled with the trace elements Co, V, Ce, Mn, Ni, Ga, Y, Rb, La, Br, Cs were predominated by crustal material sources. Simultaneously, the water-soluble ions (WS-ions) of NH4 +, SO4 2−, SO3 2−, NO3 −, SiO4 4−, HSO4 − possibly originated from coal combustion with the aid of multivariate statistical analysis. This made it possible to trace the amount of trace element pollutants in time and in relation to dust storm conditions.Display Omitted
Keywords: Atmospheric fallouts (AFs); Water-soluble ions; Heavy metals; Dust episodes; Xi'an; Chemical composition; Multivariate analysis;
Indoor air quality in hair salons: Screening of volatile organic compounds and indicators based on health risk assessment by Gianluigi de Gennaro; Lucrezia de Gennaro; Antonio Mazzone; Francesca Porcelli; Maria Tutino (119-126).
Volatile organic compounds (VOCs) are common ingredients in cosmetic products which can impact human health. This study monitored 12 hairdressing salons in order to assess the individual exposure of the people working in or frequenting these environments as well as identify the main products or activities responsible for the presence of these compounds. In each site halogenated, oxygenated, aliphatic and aromatic compounds were monitored during the work week with diffusive samplers suitable for thermal desorption and analysed using GC–MS. The study of indoor–outdoor concentration ratios and a knowledge of the composition of most of the products, whether ecological or traditional, used in the hair salons verified the presence of compounds linked to hairdressing activities. In particular, compounds widely used in products for hair care as spray lacquer and foam (butane), shampoo, balms, hair masks and oils (camphene, camphor, limonene, eucalyptol, alpha pinene, 1-methoxy-2-propanol, n-butanol and menthol), and hair dye (benzyl alcohol, isopropanol, limonene, hexane and methyl ethyl ketone) were found at much higher levels inside rather than outside the salons (mean I/O > 10). The importance of this finding is linked to the potential health hazards of some of the VOCs detected. Integrated indicators of health risk were proposed in this study to assess the criticality level and rank the investigated environments accordingly. The results of this study indicate that the level of VOC concentrations was most affected by the type of products used while the size of the environment, the efficiency of air exchange and the number of customers had less impact on those levels.
Keywords: Volatile organic compounds; Hair salons; Work activity; Ecological products; Traditional products;
Trends in the emissions of Volatile Organic Compounds (VOCs) from light-duty gasoline vehicles tested on chassis dynamometers in Southern California by Yanbo Pang; Mark Fuentes; Paul Rieger (127-135).
We present fleet average VOC emission rate trends for the longest running in-use light-duty gasoline Vehicle Surveillance Program (VSP) in Southern California. Tailpipe emissions data from a limited number of vehicles tested as part of the VSP show that the 2003 fleet average emissions decreased by about 80% for most VOCs relative to the 1995 fleet. Vehicle evaporative emission rates decreased more than 90% for most compounds from the 1999 to the 2003 fleet. Tailpipe benzene-normalized emission rate ratios for most compounds were relatively stable. Evaporative emission rate ratios and weight percentages have changed significantly from the 1999 fleet to the 2003 fleet indicating a significant change in the evaporative emission species patterns. The tailpipe NMHC (Non-Methane HydroCarbon) emission reductions observed between the 1995 fleet and the 2003 fleet likely resulted from the retirement of non-catalyst vehicles in the fleets (49%) and the combined effect of the turn-over of catalyst-equipped vehicles and switch to Phase III gasoline (27%). Our results are consistent with those observed in the Swiss tunnel study.Benzene-normalized emission rate ratios for C2 compounds, aldehydes, and 1,3 butadiene are much higher in tailpipe exhaust than those in evaporative emissions. C4–C5 hydrocarbon ratios in evaporative emissions are much higher than those in exhaust. C8 aromatic compound ratios are comparable for tailpipe and evaporative emissions (hot-soak). Such ratio differences can be used to estimate the relative contributions of vehicle exhaust and evaporative emission to ambient VOCs.The contribution of emissions from malfunctioning vehicles to total fleet emissions increased from 16% to 32% for the 1995 fleet to the 2003 fleet even though the percentage of malfunctioning vehicles in the fleet decreased from 10% to 5%. Most malfunctioning vehicles are vehicles that are at least 10 years old and generally have higher acetylene emission rate ratios. The effective identification and control of these malfunctioning vehicles will become increasingly important for improving mobile source emission estimates as well as reducing future tailpipe emissions.
Keywords: Vehicle; Emission; VOC; Trend;
Significance of wet deposition to removal of atmospheric particulate matter and polycyclic aromatic hydrocarbons: A case study in Guangzhou, China by Ling-Chuan Guo; Lian-Jun Bao; Jian-Wen She; Eddy Y. Zeng (136-144).
Rainwater samples were simultaneously collected from three locations in Guangzhou, a mega metropolitan center in South China, during the entire year of 2010, and analyzed for particulate matter (PM), total organic carbon and polycyclic aromatic hydrocarbons (PAHs), with the objectives of assessing the seasonality of washout effects and efficiency for removal of pollutants from the atmosphere by wet deposition. The contents of PM, particulate organic carbon, and dissolved organic carbon were in the ranges of 0.74–420 (average: 8.1 mg L−1), 0.16–40 (average: 1.3 mg L−1), and 0.34–6.9 mg L−1 (average: 1.4 mg L−1), respectively. Concentrations of Σ15PAH (sum of the 16 priority PAH compounds defined by the United States Environmental Protection Agency minus naphthalene) in wet deposition samples ranged from 39 to 1580 ng L−1 with an average of 170 ng L−1. The PAH concentration levels were slightly abated compared to those acquired previously in Guangzhou during the year of 2005, probably indicating a favorable change of energy consumption patterns in the region. There were moderately significant negative correlations between washout ratios and rainfall intensities (0–4.3 mm h−1). The total annual fluxes of wet and dry depositions combined for PM and PAHs in the urban area of Guangzhou were 34 g m−2 yr−1 and 6.0 × 102 μg m−2 yr−1 with 50 and 57% being contributed from wet deposition, respectively. The monthly capacity for removal (CR) of PM and PAHs (calculated as the wet deposition flux dividing the total flux) varied widely with different months, and was lower during the dry weather season (January–March and October–December) than during the wet weather season (April–September). Finally, the air quality index related to PM10 was negatively correlated to CR values of PM and PAHs, indicating the need to control the emissions of anthropogenically derived pollutants during the dry weather season.Display Omitted
Keywords: Wet deposition; Washout ratio; Removal capacity; Particulate matter; Polycyclic aromatic hydrocarbons;
The contribution of different aerosol sources to the Aerosol Optical Depth in Hong Kong by Zhenxi Zhang; Mark Wenig; Wen Zhou; Thomas Diehl; Ka-Lok Chan; Lingna Wang (145-154).
The contribution of major aerosol components emitted from local and remote regions to Hong Kong's Aerosol Optical Depth (AOD) in 2007 is quantitatively determined using the chemical transport model GOCART (Global Ozone Chemistry Aerosol Radiation and Transport). Of the major aerosol components, sulphur has the largest influence (68%) on Hong Kong, followed by organic carbon (OC, 13%) and dust (11%), and the influences of black carbon (BC, 5%) and sea salt (3%) are the lowest. The highest AOD is seen in September 2007 and is composed mainly of sulphur aerosols (85%). The high AOD values in March and April 2007 are caused by sulphur and OC. OC has a relative contribution of 39% in March and 30% in April.The anthropogenic sulphur, BC, and OC emitted from every continent, as well as from China and South China, are considered respectively. In summer, South China's contribution of sulphur aerosols from anthropogenic SO2 emissions to the total sulphur AOD in Hong Kong is more than 20%. In other seasons, sulphur aerosols from anthropogenic SO2 emissions in Rest China (all of China except South China) accounts for more than 25%. Anthropogenic BC from South China accounts for more than 20% of total BC AOD in Hong Kong in summer. The contribution of anthropogenic BC from Rest China exceeds 40% in autumn and winter. Anthropogenic BC from Rest Asia (all of Asia except China) accounts for more than 30% in summer and autumn. The contribution of anthropogenic OC from Rest China is more than 35% in autumn and winter. The contribution of anthropogenic OC from Rest Asia exceeds 20% in summer.Gobi dust accounts for more than 40% of the total dust AOD in winter, and its impact appears mainly in the Atmospheric Boundary Layer (ABL), where it is responsible for 50% of the dust concentration. The contribution of Sahara dust to the dust AOD in spring exceeds 35%, and its contribution to the dust concentration in the free atmosphere (40%) is larger than that in the ABL (10%). More than 35% of the dust AOD in summer and autumn comes from Taklamakan dust, which exists mainly in the free atmosphere, where it accounts for 40% of the dust concentration.
Keywords: Aerosol; Aerosol Optical Depth; Numerical simulation; Hong Kong;
Impact of air-borne or canopy-derived dissolved organic carbon (DOC) on forest soil solution DOC in Flanders, Belgium by Arne Verstraeten; Bruno De Vos; Johan Neirynck; Peter Roskams; Maarten Hens (155-165).
Dissolved organic carbon (DOC) in the soil solution of forests originates from a number of biologically and/or biochemically mediated processes, including litter decomposition and leaching, soil organic matter mineralization, root exudation, mucilage and microbial activity. A variable amount of DOC reaches the forest floor through deposition, but limited information is available about its impact on soil solution DOC. In this study, trends and patterns of soil solution DOC were evaluated in relation to deposition of DOC over an 11-year period (2002–2012) at five ICP Forests intensive monitoring plots in Flanders, northern Belgium. Trend analysis over this period showed an increase of soil solution DOC concentrations for all observed depth intervals. Fluxes of DOC increased in the organic layer, but were nearly stable in the mineral soil. Annual leaching losses of DOC were higher in coniferous (55–61 kg C ha−1) compared to deciduous plots (19–30 kg C ha−1) but embody less than 0.05% of total 1-m soil organic C stocks. Temporal deposition patterns could not explain the increasing trends of soil solution DOC concentrations. Deposition fluxes of DOC were strongly correlated with soil solution fluxes of DOC, but their seasonal peaks were not simultaneous, which confirmed that air-borne or canopy-derived DOC has a limited impact on soil solution DOC.
Keywords: Dissolved organic carbon; Forest soil solution; Deposition; Long-term trends; Seasonal pattern;
Simultaneous airborne nitric acid and formic acid measurements using a chemical ionization mass spectrometer around the UK: Analysis of primary and secondary production pathways by Michael Le Breton; Asan Bacak; Jennifer B.A. Muller; Ping Xiao; Beth M.A. Shallcross; Rory Batt; Michael C. Cooke; Dudley E. Shallcross; S.J.-B. Bauguitte; Carl J. Percival (166-175).
The first simultaneous measurements of formic and nitric acid mixing ratios around the United Kingdom were measured on the FAAM BAe-146 research aircraft with a chemical ionization mass spectrometer using I− reagent ions at 0.8 Hz. Analysis of the whole dataset shows that formic acid and nitric acid are positively correlated as illustrated by other studies (e.g. Veres et al., 2011). However, initial evidence indicates a prominent direct source of formic acid and also a significant source when O3 levels are high, suggesting the importance of the ozonolysis of 1-alkenes. A trajectory model was able to reproduce the formic acid concentrations by both the inclusion of a primary vehicle source and production via ozonolysis of propene equivalent 1-alkene levels. Inspection of data archives implies these levels of 1-alkene are possible after 11 am, but formic acid and nitric acid plumes early in the flight are too high for the model to replicate. These data show the relationship between nitric acid and formic acid cannot solely be attributed to related photochemical production. The simultaneous measurement of HCOOH and HNO3 has been implemented to estimate OH levels along the flight track assuming a relationship between formic and nitric acid in photochemical plumes and a constant source of 1-alkene.
Keywords: Nitric acid; Formic acid; Hydroxyl radical; CIMS;
Mercury emission from coal seam fire at Wuda, Inner Mongolia, China by Yanci Liang; Handong Liang; Shuquan Zhu (176-184).
The underground coal seam fire in the Wuda, Inner Mongolia of china is one of the most serious coal fires in the world with a history over 50 years and endangers the neighboring downwind urban area. To investigate the potential mercury emission and migration from the coal seam fire, in situ real-time measurement of total gaseous mercury (TGM) concentration using Lumex RA-915 + mercury analyzer were implemented on the fire zone and the urban area. The results show an average TGM concentration of 464 ng m−3 in the fumes released from surface vents and cracks on the fire zone, which leads to an elevated TGM concentration of 257 ng m−3 (211–375 ng m−3) in the near-surface air at the fire zone and 89 ng m−3 (23–211 ng m−3) at the peripheral area. The average TGM concentration in the adjoining downwind urban area of Wuda is 33 ng m−3. This result suggests that the coal seam fire may not only contribute to the global mercury inventory but also be a novel source for mercury pollution in the urban areas. The scenario of urban areas being adjacent to coal seam fires is not limited to Wuda but relatively common in northern China and elsewhere. Whether there are other cities under influence of coal seam fires merits further investigation.
Keywords: Total gaseous mercury; Coal seam fire; Near-Surface atmosphere; Urban area; Living environment; Wuda; Northern China;
New methodology to determine air quality in urban areas based on runs rules for functional data by J. Sancho; J. Martínez; J.J. Pastor; J. Taboada; J.I. Piñeiro; P.J. García-Nieto (185-192).
Functional data appear in a multitude of industrial applications and processes. However, in many cases at present, such data continue to be studied from the conventional standpoint based on Statistical Process Control (SPC), losing the capacity of analysing different aspects over the time. In this study, the well-known runs rules for Shewhart Type Control Charts are adapted to the case of functional data. Also, in the application of this functional approach, a number of advantages over the classical one are described. Furthermore, the results of applying this new methodology are analysed to determine the air quality of urban areas from the gas emissions at different weather stations.
Keywords: Runs rules; Functional data analysis; Gas emission;
Diurnal and nocturnal measurements of PAH, nitro-PAH, and oxy-PAH compounds in atmospheric particulate matter of a sugar cane burning region by Kely F. Souza; Lilian R.F. Carvalho; Andrew G. Allen; Arnaldo A. Cardoso (193-201).
Polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, and oxy-PAHs were studied in the atmospheric particulate matter of a subtropical rural region (São Paulo State, Brazil) affected by emissions from sugar cane burning. Diurnal and nocturnal samples were collected from May to June of 2010. In general, average PAH concentrations were significantly higher at night, suggesting that the compounds were predominantly emitted to the atmosphere during biomass burning (which was mainly performed at night). The maximum average PAH concentration was found for benzo[b]fluoranthene at night (2.9 ± 5.4 ng m−3). Among the nitro-PAH compounds, the highest average concentrations were obtained for 9-nitrophenanthrene in diurnal and nocturnal samples (1.5 ± 1.2 and 1.3 ± 2.1 ng m−3, respectively). In contrast to the PAH and nitro-PAH compounds, the oxy-PAHs could not be directly associated with sugar cane burning. The most abundant oxy-PAH compound was benzanthrone (1.6 ± 1.3 ng m−3) at night, followed by 9,10-anthraquinone (1.1 ± 0.9 ng m−3) and 9-fluorenone (0.4 ± 0.1 ng m−3) during the day.A correlation matrix was used to explore the origins of the different compounds. The data suggested that during the daytime, direct emissions (mainly in vehicle exhaust) contributed to the presence of PAHs, nitro-PAHs, and oxy-PAHs in air. Photochemical production also appeared to be a source of the majority of nitro-PAHs and oxy-PAHs, while photolysis could have contributed to removal of the nitro-PAHs during the daytime. At night, sugar cane burning emissions were the primary source of the PAHs and nitro-PAHs, with additional sources also contributing to the levels of oxy-PAHs in the atmosphere.
Keywords: Sugar cane burning; Atmospheric particulate matter; PAHs; Nitro- and oxy-PAHs; Brazil;
Characteristics of polycyclic aromatic hydrocarbons and their gas/particle partitioning from fugitive emissions in coke plants by Ling Mu; Lin Peng; Xiaofeng Liu; Chongfang Song; Huiling Bai; Jianqiang Zhang; Dongmei Hu; Qiusheng He; Fan Li (202-210).
Coking is one of the most important emission sources of polycyclic aromatic hydrocarbons (PAHs) in China. However, there is little information available on the emission characteristics of PAHs from fugitive emission during coking, especially on the specific processes dominating the gas–particle partitioning of PAHs. In this study, emission characteristics and gas–particle partitioning of PAHs from fugitive emission in four typical coke plants (CPs) with different scales and techniques were investigated. The average concentrations of total PAHs from fugitive emission at CP2, CP3 and CP4 (stamp charging) were 146.98, 31.82, and 35.20 μg m−3, which were 13.38-, 2.90- and 3.20-fold higher, respectively, than those at CP1 (top charging, 10.98 μg m−3). Low molecular weight PAHs with 2–3 rings made up 75.3% of the total PAHs on average, and the contributions of particulate PAH to the total BaP equivalent concentrations (BaPeq) in each plant were significantly higher than the corresponding contributions to the total PAH mass concentrations. The calculated total BaPeq concentrations varied from 0.19 to 10.86 μg m−3 with an average of 3.14 μg m−3, and more efficient measures to control fugitive emission in coke plants should be employed to prevent or reduce the health risk to workers. Absorption into organic matter dominated the gas–particle partitioning for most of the PAHs including PhA, FluA, Chr, BbF, BkF and BaP, while adsorption on elemental carbon appeared to play a dominant role for AcPy, AcP and Flu.Display Omitted
Keywords: PAHs; Fugitive emissions; Coking; Carcinogenic potencies; Phase distribution;
Spatial variation in particulate matter components over a large urban area by Scott Fruin; Robert Urman; Fred Lurmann; Rob McConnell; James Gauderman; Edward Rappaport; Meredith Franklin; Frank D. Gilliland; Martin Shafer; Patrick Gorski; Edward Avol (211-219).
To characterize exposures to particulate matter (PM) and its components, we performed a large sampling study of small-scale spatial variation in size-resolved particle mass and composition. PM was collected in size ranges of <0.2, 0.2-to-2.5, and 2.5-to-10 μm on a scale of 100s to 1000s of meters to capture local sources. Within each of eight Southern California communities, up to 29 locations were sampled for rotating, month-long integrated periods at two different times of the year, six months apart, from Nov 2008 through Dec 2009. Additional sampling was conducted at each community's regional monitoring station to provide temporal coverage over the sampling campaign duration. Residential sampling locations were selected based on a novel design stratified by high- and low-predicted traffic emissions and locations over- and under-predicted from previous dispersion model and sampling comparisons. Primary vehicle emissions constituents, such as elemental carbon (EC), showed much stronger patterns of association with traffic than pollutants with significant secondary formation, such as PM2.5 or water soluble organic carbon. Associations were also stronger during cooler times of the year (Oct through Mar). Primary pollutants also showed greater within-community spatial variation compared to pollutants with secondary formation contributions. For example, the average cool-season community mean and standard deviation (SD) for EC were 1.1 and 0.17 μg m−3, respectively, giving a coefficient of variation (CV) of 18%. For PM2.5, average mean and SD were 14 and 1.3 μg m−3, respectively, with a CV of 9%. We conclude that within-community spatial differences are important for accurate exposure assessment of traffic-related pollutants.
Keywords: Air pollution; Particulate matter; Traffic emissions; Spatial variability;
Chemical and toxicological properties of emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies by Seungju Yoon; Shaohua Hu; Norman Y. Kado; Arvind Thiruvengadam; John F. Collins; Mridul Gautam; Jorn D. Herner; Alberto Ayala (220-228).
Chemical and toxicological properties of emissions from compressed natural gas (CNG) fueled transit buses with stoichiometric combustion engines and three-way catalyst (TWC) exhaust control systems were measured using a chassis dynamometer testing facility and compared to the data from earlier CNG engine and exhaust control technologies. Gaseous and particulate matter emissions from buses with stoichiometric engines and TWC were significantly lower than the emissions from buses with lean-burn engines. Carbonyls and volatile organic compounds (VOCs) from buses with stoichiometric engines and TWC were lower by more than 99% compared to buses with lean-burn engines. Elemental and organic carbons (EC and OC), polycyclic aromatic hydrocarbons (PAHs), and trace elements from buses with stoichiometric engines and TWC were effectively controlled and significantly lower than the emissions from buses with lean-burn engines. Potential mutagenicity measured using a microsuspension modification of the Salmonella/microsome assay was lower by more than 99% for buses with stoichiometric engines and TWC, compared to buses with lean-burn engines and OxC.
Keywords: CNG bus emissions; Unregulated emissions; Particulate matter; Chemical characteristics; Toxicological properties;
Toward refined estimates of ambient PM2.5 exposure: Evaluation of a physical outdoor-to-indoor transport model by Natasha Hodas; Qingyu Meng; Melissa M. Lunden; Barbara J. Turpin (229-236).
Because people spend the majority of their time indoors, the variable efficiency with which ambient PM2.5 penetrates and persists indoors is a source of error in epidemiologic studies that use PM2.5 concentrations measured at central-site monitors as surrogates for ambient PM2.5 exposure. To reduce this error, practical methods to model indoor concentrations of ambient PM2.5 are needed. Toward this goal, we evaluated and refined an outdoor-to-indoor transport model using measured indoor and outdoor PM2.5 species concentrations and air exchange rates from the Relationships of Indoor, Outdoor, and Personal Air Study. Herein, we present model evaluation results, discuss what data are most critical to prediction of residential exposures at the individual-subject and populations levels, and make recommendations for the application of the model in epidemiologic studies. This paper demonstrates that not accounting for certain human activities (air conditioning and heating use, opening windows) leads to bias in predicted residential PM2.5 exposures at the individual-subject level, but not the population level. The analyses presented also provide quantitative evidence that shifts in the gas-particle partitioning of ambient organics with outdoor-to-indoor transport contribute significantly to variability in indoor ambient organic carbon concentrations and suggest that methods to account for these shifts will further improve the accuracy of outdoor-to-indoor transport models.
Keywords: PM2.5 exposure; Organic aerosol; Gas-particle partitioning; Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study; Aerosol Penetration and Persistence (APP) model;
Chemical characterisation of semi-volatile and aerosol compounds from the photooxidation of toluene and NO x by Stephen J. White; Ian M. Jamie; Dennys E. Angove (237-244).
The chemical composition of a gas phase and secondary organic aerosol (SOA) mixture from toluene photooxidation in NO x was determined. Aerosol from toluene photooxidation was generated in a smog chamber and was collected onto glass fibre filters along with those gas phase compounds which adhered to the filter. The filter bound organic material was extracted, derivatised with O-2,3,4,5,6-pentafluorobenzyl hydroxylamine (PFBHA) and N,O-bistrimethylsilyl-trifluoroacetamide (BSTFA), then analysed using gas chromatography-mass spectrometry (GC–MS). Compound identification was aided by the use of isotopically-labelled toluene. The effect of humidity on product formation was investigated by raising water vapour concentration in one experiment.Sixty compounds were identified, of which twenty had not been identified from toluene photooxidation previously. Small carboxylic acids and dicarbonyls provided the highest proportion of identifiable compounds by relative response. The use of water to extract the filter samples resulted in much higher relative responses for oxocarboxylic acids, such as glyoxylic acid and pyruvic acid, than has been observed in previous studies. The formation of levulinic acid was determined to be due to the reaction of water with aromatic photooxidation products in the gas phase or particle phase of the chamber experiment. Nuclear magnetic resonance (NMR) was used to determine the functional groups of water-extracted organic material, which indicated that the water-soluble components were comprised of compounds which contain similar functional groups, primarily alcohols and carboxylic acids.
Keywords: Toluene and NO x ; Organic aerosol; Aromatic photooxidation; Isotopologues; Humidity;
Characterizing CH4 and N2O emissions from an intensive dairy operation in summer and fall in China by Gaodi Zhu; Xiaoyuan Ma; Zhiling Gao; Wenqi Ma; Jianguo Li; Zhenjiang Cai (245-253).
Evaluation of the global warming potential of the dairy industry both in China and globally necessitates reliable characterization of CH4 and N2O emissions. However, CH4 and N2O emissions from dairy operations differ with feeds, herd structures and manure management practices, and the lack of N2O and CH4 emission measurements for China, especially for intensive dairy operations, causes substantial uncertainty in accounting for GHGs from dairy operation both in China and globally. In this study, CH4 and N2O emissions during summer to fall period from an intensive feedlot in China were characterized to fill the data gap. The diurnal CH4 emission patterns for milking cows and heifers were driven by the feeding activities and the diurnal N2O patterns by the diurnal changes in temperature. The CH4 emission rates of 397 g head−1 d−1 (23.63 L CH4 kg−1 milk) (in summer) and 279 g head−1 d−1 (in fall) for milking cows and heifers accounted for 5.17% and 7.68% of their daily gross energy intakes, whereas the N2O emission rates of 36.7 g head−1 d−1 (0.85 L N2O kg−1 milk) for milking cows and 24.2 g head−1 d−1 for heifers accounted for 4.25% and 6.86% of the daily feed N intake. The CH4 conversion factor and CH4 emission intensity in the measurement season for intensive dairy operations in China are lower than those for collective operations in China, and the CH4 emission intensity is similar to those in developed countries.
Keywords: Milking cow; Heifer; Methane; Nitrous oxide; Emission intensity;
A contribution to solve the atmospheric diffusion equation with eddy diffusivity depending on source distance by Davidson Martins Moreira; Amilton Cravo Moraes; Antonio Gledson Goulart; Taciana Toledo de Almeida Albuquerque (254-259).
An integral solution of the atmospheric diffusion equation considering wind speed as a function of vertical height and eddy diffusivity as a function of both downwind distance from the source and vertical height is presented. The near-source dispersion problem is investigated comparing a vertical eddy diffusivity function of distance from the source against their asymptotic limit. The results suggest that the inclusion of the memory effect as modeled by Taylor's theory, improves the description of the turbulent transport process of atmospheric effluent released by a low continuous source in convective conditions.
Keywords: Eddy diffusivity; Analytical model; Atmospheric boundary layer;
Adaptation of a resistive model to pesticide volatilization from plants at the field scale: Comparison with a dataset by Nebila Lichiheb; Erwan Personne; Carole Bedos; Enrique Barriuso (260-268).
Volatilization from plants is known to greatly contribute to pesticide emission into the atmosphere. Modeling would allow estimating this contribution, but few models are actually available because of our poor understanding of processes occurring at the leaf surface, competing with volatilization, and also because available datasets for validating models are lacking. The SURFATM-Pesticides model was developed to predict pesticide volatilization from plants. It is based on the concept of resistances and takes into account two processes competing with volatilization (leaf penetration and photodegradation). Model is here presented and simulated results are compared with the experimental dataset obtained at the field scale for two fungicides applied on wheat, fenpropidin and chlorothalonil. These fungicides were chosen because they are largely used, as well as because of their differentiated vapor pressures. The model simulates the energy balance and surface temperature which are in good agreement with the experimental data, using the climatic variables as inputs. The model also satisfactorily simulates the volatilization fluxes of chlorothalonil. In fact, by integrating estimated rate coefficients of leaf penetration and photodegradation for chlorothalonil giving in the literature, the volatilization fluxes were estimated to be 24.8 ng m−2 s−1 compared to 23.6 ng m−2 s−1 measured by the aerodynamic profile method during the first hours after application. At six days, the cumulated volatilization fluxes were estimated by the model to be 19 g ha−1 compared to 17.5 g ha−1 measured by the inverse modeling approach. However, due to the lack of data to estimate processes competing with volatilization for fenpropidin, the volatilization of this compound is still not well modeled yet. Thus the model confirms that processes competing with volatilization represent an important factor affecting pesticide volatilization from plants.
Keywords: Atmospheric pollution; Pollutant exchange; Fungicides; Emission; Wheat; Leaf penetration; Photodegradation;
Summertime N2O, CH4 and CO2 exchanges from a tundra marsh and an upland tundra in maritime Antarctica by Renbin Zhu; Dawei Ma; Hua Xu (269-281).
This study provides the first concurrent measurements of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) fluxes from a tundra marsh and an upland tundra in maritime Antarctica over the summers of 2007/2008 and 2011/2012. Tundra N2O and CH4 fluxes showed large spatial variations depending on local hydrological regimes. N2O sinks generally occurred at waterlogged marsh sites (−3.0 to 27.5 μg N2O m−2 h−1) whereas relatively dry and mesic sites presented weak or strong N2O sources (2.2–41.6 μg N2O m−2 h−1). Upland tundra sites showed negligible N2O emissions due to low soil TN and NH4 +–N contents. Dry/upland tundra sites showed weak to strong CH4 uptake (−4.5 to −85.8 μg CH4 m−2 h−1). The waterlogged sites showed weak to strong CH4 emissions (29.8 μg CH4 m−2 h−1–2.4 mg CH4 m−2 h−1). Both tundra marsh and upland tundra experienced a large net CO2 uptake with the greatest mean CO2 uptake rate (−92.1 mg CO2 m−2 h−1) at dry marsh sites. Mean ecosystem respiration (ER) ranged between 82.5 ± 13.2 and 174.9 ± 25.7 mg CO2 m−2 h−1 at all the sites, and showed a strong exponential correlation (P < 0.001) with 0–10 cm soil temperature. Gross photosynthesis (P g) was more than two times higher in tundra marsh than in upland tundra due to the difference of vegetation coverage. N2O flux showed a strong negative correlation (P < 0.01) with 0–10 cm soil temperature at the marsh sites, and significant or weak positive correlations with total daily radiation (TDR) and sunlight time (ST). No significant correlation was obtained between CH4 fluxes and environmental variables at tundra marsh and upland tundra sites. There was a significant negative correlation (P < 0.01) between NEE and 0–10 cm mean soil temperature, total daily radiation. Our results indicated that the lowering of water table significantly increased N2O emissions and CH4 consumption, but decreased C loss from the tundra marsh. In the future, the combination of climate warming and frequent precipitation will alter tundra hydrological conditions, and thus decrease N2O emission and CH4 consumption from maritime Antarctic tundra.
Keywords: N2O; CH4; CO2; Greenhouse gas fluxes; Tundra; Antarctica;
Influence of wind speed on optical properties of aerosols in the marine boundary layer measured by ship-borne DePolarization Lidar in the coastal area of Korea by Dong Ho Shin; Detlef Müller; Taejin Choi; Young Min Noh; Young Jun Yoon; Kwon H. Lee; Sung Kyun Shin; Namyi Chae; Kwanchul Kim; Young J. Kim (282-290).
Shipboard measurements of microphysical and optical properties of marine boundary-layer aerosols were performed around the Korean Peninsula from 2 to 5 December 2009. The measurements were conducted aboard the Korean icebreaking research vessel Araon during cruise tracks in the East Sea of Korea near Busan and Pohang. This paper describes the results of optical aerosol measurements acquired with a DePolarization Lidar (DPL) and an optical particle counter (OPC) and data on meteorological parameters. Backward trajectory analyses indicate that two different aerosol characteristics according to different pathways of air mass were encountered during the cruise. We find a high correlation between wind speeds across the east coast of Korea and extinction coefficient, depolarization ratio and mass concentration Correlation coefficient (R 2) are 0.57, 0.52 and 0.67, respectively. The increase of extinction coefficient, depolarization ratio and number concentration with wind speed may have been caused by the increase of sea-salt aerosol production and transport.
Keywords: Lidar; Aerosol; Wind speed; Marine boundary layer;
Long term (2003–2012) spatio-temporal MODIS (Terra/Aqua level 3) derived climatic variations of aerosol optical depth and cloud properties over a semi arid urban tropical region of Northern India by Adarsh Kumar (291-300).
Aerosol optical depth (AOD) values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's Terra and Aqua satellites, for the 10 years period of 2003–2012 have been analyzed in the present study. The retrieved satellite data (Terra/Aqua) has been used to investigate the temporal heterogeneity in columnar aerosol characteristics over a semi arid urban tropical Delhi zone (28° 34′, 77° 07′, 233 m ASL) of Northern India with a resolution of 1° × 1° grid in magnitude. Aerosol optical depths have found to be increased >25% across Delhi region of India during the study period of 2003–2012. Yearly mean Terra/Aqua AOD values have shown an increasing trend at a rate of 0.005/0.009 per year respectively. However, seasonally winter means Terra/Aqua AOD values exhibit an increasing trend at a rate of ∼0.012/0.007 per year respectively. In order to provide a better understanding of aerosol–cloud interaction, a single paired one tailed distribution student's t-Test has been applied to the Terra AOD values and cloud parameters. The results extracted in the present study are compared with the earlier studies as well as with the AOD values over various other Indian regions.
Keywords: MODIS; Northern India; AOD; Total cloud cover; Water vapor;
Importance of direct anthropogenic emissions of formic acid measured by a chemical ionisation mass spectrometer (CIMS) during the Winter ClearfLo Campaign in London, January 2012 by Thomas J. Bannan; Asan Bacak; Jennifer B.A. Muller; A. Murray Booth; Benjamin Jones; Michael Le Breton; Kimberley E. Leather; Mohamed Ghalaieny; Ping Xiao; Dudley E. Shallcross; Carl J. Percival (301-310).
Formic acid, an ubiquitous trace gas in the atmosphere, was measured using a chemical ionisation mass spectrometer (CIMS) during the winter ClearfLo campaign in London, 2012. Daily calibrations of formic acid gave sensitivities of 3 ion counts s−1 pptv−1 for the complete campaign and a limit of detection of 2 ppt. No correlation with nitric acid was observed, R 2 of 0.137, indicating no significant secondary source of formic acid. However, a strong positive correlation with NOx, CO, and production in line with rush hour periods indicated a direct anthropogenic emission of formic acid from vehicle emissions. Peaks of 6.7 ppb of formic acid were observed with a mean of 610 ppt. Global models indicated that this emission source dominates in the northern hemisphere where global models underestimate formic acid most significantly, thus increasing the accuracy of modelling of global formic acid emissions.
Keywords: Formic acid; CIMS; ClearfLo; Troposphere;