International Journal of Environment and Pollution (45 papers in press)
Are toxic load-based toxicity models consistent with experimental observations? Independent analysis of steady-exposure data from the 20122013 ECBC/NAMRU-D toxicological experiments
by Alexander Slawik, Kevin Axelrod, James Silva, Ivo Dimitrov, Jeffry Urban, Nathan Platt
Abstract: This work explores the validity of the toxic load model, which is often used to predict the health effects of airborne releases of toxic materials. In 2012 and 2013 the US Army's Edgewood Chemical and Biological Center (ECBC) and the Naval Medical Research Unit Dayton (NAMRU-D) conducted toxicological experiments to explore the effects of time-varying inhalation exposures of hydrogen cyanide gas on rats. Our independent analysis of the experimental data indicates that the toxic load model is not valid over the full range of the experiments exposure durations, assuming that there was no systematic experimental error. The model fits the data poorly for exposure durations under 10 minutes.
Keywords: toxicology; toxic load; toxic load model; toxicity model; hazardous materials; acute inhalation exposure; steady exposures; consequence assessment; health effects; health and exposure assessment; hydrogen cyanide; rats; ECBC; NAMRU-D; DTRA.
Relationships between water and sediment quality parameters and faecal bacteria content in the Palic-Ludas canal, Serbia
by Zeljka Rudic, Bojana Vujovic, Mile Bozic, Tanja Arizanovic, Vera Raicevic
Abstract: The objective of this paper is to emphasise how faecal bacteria persist in canal sediment and relate to abiotic factors in a peri-urban canal. Mann-Whitney tests confirmed that there is a considerable difference in water quality of upstream and downstream end of the canal, which supports the claim that water quality is affected by wastewater discharge. Strong positive correlations between enterococci and organic matter, TOC, and all nitrogen forms in sediment show that the large amount of organic matter in sediment is linked to high enterococcal counts. High counts of Escherichia coli in sediment, as well as weak correlations between E. coli and sediment quality parameters, together with water quality changes, indicate a 'fresh' pollution of an aquatic system. In conclusion, our study suggests that wastewater discharge makes a long term contribution to the increased content of E. coli and enterococci in the Palic-Ludas canal.
Keywords: Escherichia coli; enterococci; environmental pollution; Mann-Whitney test; Spearman correlation.
Physicochemical characterisation of soil amendments derived from residual materials and their effects on soil fertility
by Zahra Derakhshan-Nejad, Myung Chae Jung
Abstract: Soil remediation by stabilisation/solidification, which is a process that involves mixing of contaminated soil with binders (amendment) to reduce the volume of contaminant leachability, has shown huge promise in dealing with the cleanup of soils contaminated with hazardous substances. Hence, this study was carried out to characterise physicochemical properties of residual materials (i.e., rice husk, RRH; rice husk biochar, RHB; maple leaf, RML; maple leaf biochar, MLB; red mud, RM; and steel slag, SS) to guarantee the right identification for applying them as soil amendments. In addition, the influence of amendments on soil water holding capacity (WHC) and cation exchange capacity (CEC), as critical factors for soil fertility, was examined. Pyrolysis of RRH and RML at 550 0C caused an increase in specific surface area (SSA), aromatic carbon rings, and pH of the resultant RHB and MLB. Results of the infrared spectrum identified hydroxyl bonds of gibbsite in RM and silica bonds in SS. Strong negative zeta potential (ZP) values for RRH, RML, and biochars was observed. However, RM and SS showed both negative and positive values for ZP depending on the pH condition. Applying RHB, MLB, RM, and SS as soil amendments for a contaminated site showed promising results to increase soil CEC, WHC and metals immobilisation.
Keywords: soil remediation; rice husk; maple leaf; biochar; red mud; steel slag.
Quercus ilex as bio-indicator of metal pollution in the area of Terni, Italy
by Loretta Gratani, Maria Fiore Crescente, Rosangela Catoni, Ilaria Rita Guiducci, Donatella Bartoli, Gaia Piccini, Romina Quondam Luigi, Federica Rocchi, Laura Varone
Abstract: Trees are effective scavengers of both gaseous and particulate pollutants from the atmosphere. The objective of this research was to evaluate heavy metal pollution in the territory of the steel factory Acciai Speciali Terni S.p.A (Italy) by monitoring Quercus ilex trees naturally growing in the area. Measurements were carried out in three sites (site 1, 2 and 3) at different distances from the steel factory (1.9, 2.3 and 7.2 km from the factory, respectively). The most part of the metals (As, Ba, Cd, Cr, Fe, Ni, Pb, V and Zn) had a decreasing trend from site 1 to site 3. Among them, Cr showed the highest decrease (97%) and Zn the lowest (44%). At a morphological level, leaf mass area (LMA) was lower at site 3 (12.9
Keywords: Quercus ilex; metal pollution; leaf morphology; leaf rolling; steel factory.
Kinetic conditions of struvite continuous reaction crystallization from wastewater in presence of aluminum(III) and iron(III) ions
by Nina Hutnik, Anna Stanclik, Krzysztof Piotrowski, Andrzej Matynia
Abstract: Kinetic parameters of the continuous struvite reaction crystallization process from aqueous solutions containing phosphate(V) ions with impurities: aluminum(III) or/and iron(III) ions were determined. Simplified kinetic model of ideal MSMPR (Mixed Suspension Mixed Product Removal) crystallizer SIG (Size Independent Growth) was adopted. Nuclei population densities, nucleation rates and crystal linear growth rates were determined from product crystal size distributions. It was concluded, that within the assumed process parameter ranges linear growth rate of struvite crystals in presence of aluminum(III) ions varied from 4.53∙109 to 1.89∙108 m/s, whereas in presence of iron(III) ions within the 4.59∙109 1.62∙108 m/s range. Nucleation rate, varied within the 3.8∙107 1.6∙109 1/(sm3) and 4.5∙107 1.2∙109 1/(sm3) ranges, correspondingly. These large differences show significant influence of impurities and technological parameters on the struvite reaction crystallization kinetics, thus on the product quality. It was experimentally demonstrated, that aluminum(III) ions affect struvite reaction crystallization more advantageously than iron(III) ions.
Keywords: struvite; phosphate(V) ions; aluminum(III) ions; iron(III) ions; continuous reaction crystallization; SIG MSMPR kinetic model; wastewater; phosphorus recycling.
Impacts of global climate scenarios over three European cities using mesoscale and CFD simulations with very high horizontal resolution
by Libia Pérez, Roberto San Jose, Juan Luis Perez, Rosa Maria Gonzalez-Barras, Julia Pecci, Marino Palacios
Abstract: This contribution presents the results of a climate and air pollution dynamical downscaling process from global climate simulations to urban scale with 50 m spatial resolution. The final objective is to show how urban meteorological and air pollution respond to different global climatic conditions and how human health could be affected by changes induced by global warming emissions. We have used the mesoscale model WRF-Chem (NOAA, US) to produce information covering all Europe with 25 km spatial resolution and two nested domains with 5 km and 1 km of spatial resolution over Madrid, London and Milan. Finally a detailed simulations using MICROSYS-CFD model are implemented to take into account the buildings of the city. The energy fluxes are calculated with the NOAH land surface model and the UCM (Urban Canopy Model), considering the shadows and reflections of the buildings. Year 2011 is used as reference year and 2030, 2050 and 2100 for future under two RCP scenarios of the IPCC, 4.5 (peak around 2040, then decline) and 8.5 (emissions continue to rise throughout the 21st century). Boundary conditions are taken from the global climate model CESM with a frequency of six hours. For evaluation we make a comparison between results of a simulation for present situation (2011, with reanalysis data as boundary and initial conditions) and observations showing acceptable agreement with measurements. The results are analysed with climate and health indicators for mortality and morbidity, using epidemiological studies to fix the exposure-response functions. The purpose is to highlight areas with elevated vulnerability to prepare plans and implement adaptations to reduce human health effect of climate change.
Keywords: Dynamical downscaling; Climate; Health; CFD.
Special Issue on: Organic Pollutants in Different Compartments of the Biosphere - Origins, Emissions, Abatement and Destruction, Risk Analysis
Catalytic decomposition of 1,2-dichlorobenzene over V2O5/TiO2 catalysts blending with typical carbon nanotubes
by Cuicui Du, Xuan Cao, Shengyong Lu
Abstract: A series of V2O5/TiO2-CNTs catalysts, prepared by the sol-gel method, were studied on their activities for 1,2-dichlorobenzene (1,2-DCBz) decomposition. Three kinds of typical carbon nanotubes, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNT1) with outer diameter of 20-30 nm, and multi-walled carbon nanotubes with thinner walls (MWCNT2), were used. The gelling time has an important effect on the textural properties and acidity of the catalysts prepared by this sol-gel method. Owing to its excellent adsorption ability, the V2O5/TiO2-SWCNTs exhibit the best reactivity at low temperature (150
Keywords: catalytic oxidation; carbon nanotubes; 1,2-dichlorobenzene; gelling time.
Fly ash from a Belgian stoker-type municipal solid waste incinerator
by Mengmei Zhang, Junhong Liao, Alfons Buekens, Xiaodong Li
Abstract: This study establishes some salient characteristics of fly ash from municipal solid waste incineration by combining various instrumental analytical techniques (SEM-EDS, XRD and XRF, etc.) while analysing size-classified fractions of high-temperature (HT) and baghouse (BH) dust. First, the two samples were sieved in eight (HT) or six (BH) size fractions and these were separately analysed for PCDD/F, PCB and PAH. These two samples, showing distinct differences from each other, were collected from a small MSWI stoker plant in Belgium with frequent operational problems. The BH sample presented more homogeneity than the HT sample. The variation in main elemental composition between different fractions of the same sample was limited; while a growing concentration of heavy metals was observed with falling size of particle. The loads of PCDD/F and PCB in the BH sample are one to two orders of magnitude larger than those in HT samples, while the load of PAH shows no obvious evolution. High internal correlation was found for the contents of PCB and PCDD/F and even higher for dl-PCB and PCDD/F. The primary purpose of this study is verifying in how far such off-line fly ash analyses supplement the continuous routine emission monitoring, mandatory for such plants, and developing an additional understanding of the operating state of the plant and its potential to form PCDD/F, PCB and PAH. The secondary purpose is to test a range of methods for studying fly ash arising from large-scale plant in China, provide a West European point of reference and improve operating methods and decrease emissions.
Keywords: fly ash; municipal solid waste incineration; polychlorinated dibenzo-p-dioxins; polychlorinated dibenzofurans; polychlorinated biphenyls; polycyclic aromatic hydrocarbons.
Polychlorinated dibenzo-p-dioxins and dibenzofurans in off-gas and residue during desulphurisation of iron ore sintering off-gas
by Yibo Zhang, Rong Zhu, Jingling Yang, Alfons Buekens, Hui Wang, Yun Wang, Pu Zhang
Abstract: The iron ore sintering process has always been considered as a key issue in the discharge of PCDD/Fs pollutants. In this study, the concentration of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), in brief dioxins (PCDD/Fs), was measured in the off-gas and solid by-products from two selected and distinct desulphurisation processes, one operating wet and one dry on sintering off-gas. All samples analysed showed a PCDFs to PCDDs ratio larger than unity. The removal efficiency obtained in the two facilities was almost identical, about 40%, when based on the toxic equivalent quantity (TEQ); the removal efficiency of PCDD/Fs was higher, however, with 40.4% and 63.5%, respectively, for the wet and the dry processes. Unexpectedly, the removal efficiency was strongly dependent on chlorination level and far higher for low chlorinated PCDD/Fs than for high chlorinated PCDD/Fs, showing even negative removal efficiency. Moreover, the Hagenmaier profile was markedly different for the gas phase samples than for residue. These findings suggest that these results are not representative for steady-state conditions. During desulphurisation both physical effects, such as adsorption, and chemical reactions, as well as memory effects, may have occurred. This study provides some supporting information for multiple pollutant control and disposal of desulphurisation by-products, taking into account its PCDD/Fs load. Further work is needed to explain, e.g., the deep difference between the two PCDD/Fs sintering signatures at the entrance and at the exit of the two lines, the removal mechanisms operating during wet and dry desulphurisation and the possibilities to improve the PCDD/Fs removal during gas treatment. Further work should emphasise establishing balances over both units, identifying the rate-controlling steps in wet and dry SO2 removal systems and deriving complete fingerprints, so that their mechanisms of influence may be established.
Keywords: PCDD/Fs; desulphurisation; iron ore sintering; off-gas cleaning; by-product.
Soil pollution by chlorobenzenes and polychlorinated biphenyls from an electronic waste recycling area in northern Vietnam
by Chiya Nishimura, Go Suzuki, Hidenori Matsukami, Tetsuro Agusa, Masaki Takaoka, Shin Takahashi, Nguyen Minh Tue, Pham Hung Viet, Shinsuke Tanabe, Hidetaka Takigami, Takashi Fujimori
Abstract: We investigated soil pollution by chlorobenzenes (CBzs) and polychlorinated biphenyls (PCBs) in Bui Dau, a village in Vietnam known for informal electronic waste (e-waste) recycling activities. The total concentrations of CBzs and PCBs ranged from 17 to 1400 ng/g and 2.0 to 7200 ng/g, respectively, with the highest concentrations of the two compounds detected at e-waste open burning sites (EOBSs) in the survey area. The homologue profiles of CBzs and PCBs in the soils collected at the EOBSs were different from those in municipal solid waste incinerator (MSWI) fly ash. This result suggests that CBzs are formed from different processes during the open burning of e-waste and municipal solid waste incineration, even though both are combustion processes. The spatial distributions of CBzs and PCBs, and the results of a multiple comparison test, showed that these compounds were released from the EOBSs and spread around this survey area.
Keywords: chlorobenzenes; polychlorinated biphenyls; e-waste open burning; soil; Vietnam.
Effect of microwave treatment onto activated carbon produced from pecan nut shells for tartrazine removal from aqueous media
by Jonatan Torres-Pérez, Gabriela Muñoz-Armenta, Simón Yobanny Reyes-López
Abstract: The processes used to fabricate carbonaceous materials with sorption capacity are expensive and require the exploitation of natural resources. The use of microwave treatment for activated carbons is an innovative and cheaper method than traditional chemical activation. To develop a sustainable carbonaceous material with sorption properties, the present study used four methods to prepare activated carbon using pecan nut shells, an agricultural waste, as an alternative precursor instead of conventional materials such as coconut shells or wood. The preparation methods were: carbonisation (NAC), carbonisation/water activation (NAC-H2O), carbonisation/microwave treatment (NAC-MW) and carbonisation/activation/microwave treatment (NAC-H2O-MW). The prepared material was characterised by pHPZC and total ash content determination, BET surface area analysis, Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The sorption equilibrium time for the tartrazine dye sorption was determined. The prepared activated carbons that presented the best sorption capacity were NAC-H2O (8.2 mg/g) and NAC-MW (5.1 mg/g); the sorption equilibrium time was 24 h for both materials. The sorption experiments showed a good fitting to a pseudo second order equation and to the Freundlich model.
Keywords: activated carbon; microwave activation; tartrazine; pecan nut shells; adsorption.
Special Issue on: Challenges in the Development of Large-scale Pollution Models
Urban areas parameterisation for CFD simulation and cities air quality analysis.
by Maria Grazia Badas, Luca Salvadori, Michela Garau, Giorgio Querzoli, Simone Ferrari
Abstract: The aim of this work is to highlight the importance of a site-specific characterisation of urban areas needed for Computational Fluid Dynamics (CFD) simulations and urban air quality studies. As a case study, we consider Cagliari, an Italian town, whose heterogeneous urban form can be representative of many European historical towns, quite different from large American cities that are generally analysed in the literature. Basic steps needed to compute the main morphometric and fluid dynamics parameters from Digital Elevation Models (DEM) are reviewed and some possible caveats on using gridded DEM analysis are highlighted. Results show how site-specific analysis provides quite different parametrisations from those obtained by literature results, which cannot be transposed to other urban contexts. Morphometric site-specific analysis represents a key issue in urban numerical simulations, since the application of non-representative morphometric input data may dramatically affect their results.
Keywords: morphometric parameters; urban aerodynamic roughness; urban canopy model.
On convergence of difference schemes for Dirichlet IBVP for two-dimensional quasilinear parabolic equations
by Piotr Matus, Dmitriy Poliakov, Dorota Pylak
Abstract: For the Dirichlet initial boundary value problem (IBVP) for two-dimensional quasilinear parabolic equations, a monotone linearised difference scheme is constructed. The uniform parabolicity condition is assumed to be fulfilled for the sign-alternating solution only in the domain of exact solution values (unbounded nonlinearity). On the basis of the proved new corollaries of the maximum principle not only two-sided estimates for the approximate solution y but also its belonging to the domain of exact solution values are established. We assume that the solution is continuous and its first derivatives have discontinuities of the first kind in the neighborhood of the finite number of discontinuity lines. An existence of a time derivative in any sense is not assumed. Convergence of the approximate solution to a generalized solution of differential problem in the grid norm L2 is proved.
Keywords: difference schemes ; generalised solution ; initial boundary valuernproblem ; 2D quasilinear parabolic equation ; unbounded nonlinearity ; two-sided estimates.
The treatment method of general heat treatment of waste water from metal manufacturing based on photocatalysis
by Ning Qiu
Abstract: Photocatalytic treatment of emulsified waste liquid after pretreatment is carried out using TiO2 as catalyst, and the influence of crystal structure, particle size, amounts of catalyst and the initial pH value on the removal ratio of the chemical oxygen demand (COD) are studied. The results show that in the conditions that 0.5% quality point, P25-1 photocatalyst, 6.5 pH value and 90 min processing, the treatment effect is most ideal.
Keywords: heat treatment cleaning; emulsion; photocatalysis; post-treatment.
Assaying SARIMA and generalised regularised regression for particulate matter PM10 modelling and forecasting
by Snezhana Gocheva-Ilieva, Atanas Ivanov
Abstract: Two different predictive modelling approaches classical SARIMA time series methodology and the new Generalized PathSeeker (GPS) regularized regression method - supported by stochastic gradient boosting trees, RuleLearner and other data mining techniques, are used to examine the concentration of particulate matter PM10 in the town of Kardzhali, Bulgaria. Empirical models are developed to simulate and forecast pollution levels based on hourly PM10 data from 1 January 2011 to 28 February 2014 in dependence on six meteorological variables. The constructed models have been used for 5-days-ahead hourly forecasts, compared with actual data from 1 to 5 March 2014. The obtained SARIMA and GPS models fit very well to historical data with coefficients of determination R2 = 90% and 82%, and root mean square error RMSE = 0.114 and 0.151, respectively. But in forecasting GPS models outperform SARIMA approach. This could be explained by the preliminary classification provided by the data mining techniques and cross-validation procedure.
Keywords: air pollution; particulate matter PM10; seasonal ARIMA; generalised PathSeeker regularised regression; stochastic gradient boosting; data mining; forecasting.
Special Issue on: HARMO 18 Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes
Evaluation of parametric laws for computing the wind speed profile in the urban boundary layer: Comparison to two dimensional building water channel data
by Annalisa Di Bernardino, Armando Pelliccioni, Paolo Monti, Giovanni Leuzzi, Giorgio Querzoli
Abstract: The wind flow in urban canopies depends mostly on the geometry of the roughness elements present above the surface. Given the impracticality of obtaining relationships strictly related to the governing equations, the wind-speed profile is evaluated in current practice by means of similarity laws, whose parameters are usually based on the morphometric method. This study analyses some of the empirical laws found in the literature adopted to determine the wind-speed profile above the canopy layer in neutral conditions. Their performance is tested against water-channel data simulating an idealised two-dimensional array of regular buildings of constant height.
Keywords: building; canopy layer; logarithmic law; neutral boundary layer; similarity theory; wind profile.
Validation of numerically forecasted vertical temperature profile with measurements for dispersion modelling
by Bostjan Grasic, Primoz Mlakar, Marija Zlata Boznar, Jus Kocijan
Abstract: Modelling of air pollution dispersion in the immediate vicinity of industrial sources over a complex terrain requires proper meteorological input data regarding the state of the atmosphere. For this purpose, numerical weather prediction-model results, rather than direct measurements, are becoming more widely used. In order to ensure high-quality modelling of the air-pollution dispersion, the forecast meteorological input data have to be of high quality. The quality of numerically obtained data has to therefore be validated with measurements. Measurements of the vertical temperature profile, which is vital, with Radio Acoustic Sounding System (RASS) were used in this study. The paper presents the validation of the forecast vertical temperature profile over the complex terrain of the Krko Basin. The validation is carried out with sensor measurements from a 70 metre tall tower and remote RASS measurements. 13 months worth of data is used for the validation study.
Keywords: vertical temperature profile; weather forecast validation; WRF; RASS; complex terrain.
Computer simulations of the impact of air pollution on the quality of life and health risks in Bulgaria
by Ivelina Georgieva, Vladimir Ivanov
Abstract: The air is the living environment of human beings and atmospheric composition has a great importance for the quality of life and human health. Air Quality (AQ) is a key element for the well-being and quality of life of European citizens. The objective of the present work is performing reliable, comprehensive and detailed studies of the impact of lower atmosphere composition on quality of life for the population in Bulgaria. The AQ study is based on atmospheric composition numerical simulations. USEPA Models3 System was applied as tool for 3D simulations. The AQ Index provides an integrated assessment of the impact of air pollutants on human health and is calculated on the basis of the air pollutant concentration obtained from numerical modelling. A comprehensive ensemble of atmospheric composition fields was created and diurnal variations of the recurrence spatial distribution of different classes of the AQI are demonstrated in the present work.
Keywords: air quality; ensemble of numerical simulation; air quality indices; quality of life; health risks.
Contribution of different emission sources to the atmospheric composition format in the city of Sofia
by Georgi Gadzhev, Ivelina Georgieva, Kostadin Ganev, Nikolay Miloshev
Abstract: Some extensive numerical simulations of the atmospheric composition fields in Sofia city have been recently performed and an ensemble, comprehensive enough as to provide statistically reliable assessment of the atmospheric composition climate has been constructed. The US EPA Models-3 system was chosen as a modelling tool. As the NCEP Global Analysis Data with 1 degree resolution is used as meteorological background, the system nesting capabilities were applied for downscaling the simulations to a 1 km resolution. The national emission inventory and the TNO inventory were used as an emission input. The study is based on a large number of numerical simulations carried out day by day for years 2008-2014 for six emission scenarios with all the emissions included and with reduced: all the emissions, emissions from energetics, from non-industrial, industrial combustions and road transport. Results concerning the contribution of the different emission categories are demonstrated in the paper.
Keywords: urban air pollution; computer simulations; SNAP categories; contribution of different emission sources.
Effect of surface roughness on turbulence, ventilation and pollutant dispersion over a hypothetical urban area
by Ziwei Mo
Abstract: Wind flows and pollutant dispersion over cities are strongly affected by urban morphology. Scientific evidence measuring the effect of surface roughness on transport processes is needed to effectuate air quality strategy. Based on idealised building models assembled by ribs and LEGO
Keywords: air exchange rate; pollutant dispersion coefficient; rough-surface drag; street-level ventilation; wind tunnel experiments.
A hybrid CFD RANS/Lagrangian approach to model atmospheric dispersion of pollutants in complex urban geometries
by Meïssam L. Bahlali, Eric Dupont, Bertrand Carissimo
Abstract: In the general context of atmospheric dispersion in urban neighborhood or around an industrial site, Lagrangian models consist of calculating and tracking the trajectories of particles of pollutant emitted into the turbulent atmosphere. These models are particularly suitable for the study of complex, unsteady or inhomogeneous flows, which is precisely the case of atmospheric flows in urban areas and complex industrial sites. They are also recommended to deal with dispersion near the sources. Usually, these models use wind and turbulence fields computed by an external code.
In this work, the objective is to compare the Lagrangian and the Eulerian atmospheric dispersion modules in the same Computational Fluid Dynamics (CFD) open source code (Code_Saturne), therefore using the same wind and turbulence field for both. For each simulation, we compare the turbulent dispersion of pollutants obtained with the Lagrangian approach to the existing results previously obtained with the Eulerian methods. The Lagrangian stochastic model used in this work is the Simplified Langevin Model (SLM) of Pope (2000) and pertains to the approaches referred to as PDF (Probability Density Function) methods. This formulation of model has been extensively used in the fields of turbulent combustion or multiphase flows, but to our knowledge, it has not been widely used in atmospheric applications. In this paper, we first show that the SLM respects the well-mixed criterion for uniform and non-uniform flows. Then, we validate the model in the case of a continuous point release with uniform mean wind speed and turbulent diffusivity, by checking with the existing analytical solution. Finally, we validate the model with several experimental campaigns, considering atmospheric stratification and buildings. The first field experiment program considered in this paper has been conducted on the SIRTA site (Site Instrumental de Recherche par T
Keywords: atmospheric dispersion; Lagrangian stochastic modelling; turbulence; CFD.
Data assimilation at local scale to improve CFD simulations of atmospheric dispersion: application to 1D shallow-water equations and method comparisons
by Cécile L. Defforge, Bertrand Carissimo, Marc Bocquet, Patrick Armand, Raphaël Bresson
Abstract: Atmospheric dispersion modelling requires meteorological inputs over local domains with possibly complex topographies. These local wind fields may be difficult to simulate with CFD models, in particular because of their sensitivity to geometrical features and to model inputs, especially the boundary conditions which are generally provided by larger-scale models or measurements. Using data assimilation, a few measurements inside the domain could add information to the imprecise boundary conditions and thus greatly enhance the precision of the dispersion simulations. Three data assimilation techniques (3DVar, the back and forth nudging algorithm, and the iterative ensemble Kalman smoother) have been adapted to local scale simulations by taking boundary conditions into account instead of initial conditions for which they are usually applied. Their performances have been evaluated at small scales, with a simple flow, using 1D solution of the shallow water equations.
Keywords: data assimilation; local scale simulation; boundary conditions; shallow water model; 3D-Var; back and forth nudging algorithm; iterative ensemble Kalman smoother.
QualeAria: European and national scale air quality forecast system performance evaluation
by Alessio D'Allura, Matteo Paolo Costa, Camillo Silibello
Abstract: Air quality forecasts are operationally provided by some of the Italian Regional Environmental Agencies. Some of them adopted a coherent modelling framework and implemented the same boundary conditions provided by the national forecast system QualeAria. This network of regional/urban scale air quality forecast systems represents an effective example of consistent methodology adopted to address the requirements of the European Directives, to assess, manage and forecast the state of the atmosphere. QualeAria has been evaluated against the observations recorded by regional air quality networks for the years 2015/2016. The role of phenomena generated at regional/global scales, along with the key role of fine-grained information available at local scale has been investigated by comparing QualeAria with the linked systems at different scales.
Keywords: air quality forecast; model evaluation; bias correction; score analysis.
Large-eddy simulation studies for predicting plume concentrations around nuclear facilities using an overlapping technique
by Hiromasa Nakayama, Tetsuya Takemi
Abstract: We propose, in emergency response to nuclear accidents, a practical and quick local-scale atmospheric dispersion calculation method using an overlapping technique. First, we pre-calculate large-eddy simulation (LESs) of plume dispersion around an actual nuclear facility under idealised atmospheric conditions with 36 wind-direction cases and make a dataset of the 10-minute averaged concentrations for each wind direction case. Then, we conduct LESs of plume dispersion for 1-hour periods under realistic atmospheric conditions using the meteorological data and estimate the spatial distributions of the 1-hour averaged concentrations by overlapping the pre-calculated concentration data depending on the frequency of the mean wind directions. It is shown that the concentration distribution patterns are well reproduced in comparison with those under the realistic conditions. It is concluded that the atmospheric dispersion calculation method using the overlapping technique has potentially a high performance in emergency responses to nuclear accidents.
Keywords: large-eddy simulation; plume dispersion; overlapping technique; emergency response.
Downwind chlorine hazard estimates for the 20152016 Jack Rabbit II campaign
by Nathan Platt, Kevin Luong, Jeffry Urban
Abstract: We present estimates of the downwind inhalation health hazard to humans based on measurements during the Jack Rabbit II campaign, a two-year experimental campaign of large-scale outdoor chlorine releases at the US Armys Dugway Proving Ground. We estimated the chlorine inhalation hazard at each downwind arc of chlorine sensors using two methods. We calculated the probability of lethal, severe, and mild health effects in civilian and military populations using a modification of the toxic load model, a US Department of Defense (DoD)-approved toxicological model. We also determined whether the chlorine exposures exceeded the US Environmental Protection Agencys Acute Exposure Guideline Levels (AEGLs) for chlorine at all three levels of health effects severity. The chlorine releases considered in this study were in the range of 7 to 9 metric tons. Lethal, severe, and mild health effects are expected up to 1 km, 2 to 5 km, and more than 11 km downwind from the release, respectively. The AEGL-3, AEGL-2, and AEGL-1 acute inhalation hazard thresholds are expected to be exceeded at 2 to 5 km, up to 11 km, and beyond 11 km downwind from the release, respectively. We note that since our hazard distance estimates are based on chlorine concentrations that were directly measured (i.e., not modelled), the accuracy of these estimates depends only on the quality of the health effects models we applied, and not on the quality of any atmospheric transport and dispersion model or container release (chemical source term) model
Keywords: chlorine exposure health effects; toxic industrial chemicals; Jack Rabbit II; toxic load model; AEGLs.
Source term estimation using an adjoint model: a comparison of two different algorithms
by Gianni Tinarelli, Francesco Uboldi, Giuseppe Carlino
Abstract: The location of an unknown source and its pollutant emissions are estimated from concentration observations by means of two approaches, both making use of the adjoint of a Lagrangian particle dispersion model. In the first approach, plausible source locations are estimated by identifying areas with maximum spatial and temporal consistency among backward trajectories from each sensor. In the second approach, a variational method is used to minimise the objective function and to estimate emissions at each grid-box reached by backward trajectories: the resulting map provides information on the source location and on its uncertainty. In both approaches, use is made of zero measurements to define upstream exclusion zones where emission sources cannot be located. The two methods are compared using a hierarchy of test cases, starting from a controlled field experiment up to real world operational cases. The main sources of uncertainty are discussed.
Keywords: STE algorithm; inverse dispersion modelling; adjoint model; Lagrangian particle model.
Preliminary evaluation of CMAQ modelled wet deposition of sulphur and nitrogen over Bulgaria
by Emilia Georgieva, Elena Hristova, Dimiter Syrakov, Maria Prodanova, Ekaterina Batchvarova
Abstract: Wet depositions of sulphur and nitrogen over Bulgaria have been simulated by the WRF-CMAQ system for the period from March to June 2016. Precipitation amounts have been overestimated - the average NMB is 44% for the country and 70% for Sofia. Precipitation chemistry data from Sofia have been used for the estimation of observed sulphur and nitrogen depositions - 602 mg m-2, and 528 mg m-2, respectively. Modelled wet depositions show overestimation, more significantly for sulphur deposition (NMB 87%). A precipitation adjustment has been applied as post-processing to model wet depositions. The correction led to decrease in NMB for sulphur wet deposition (9%), while nitrogen monthly depositions were in general underestimated. Possible effects of long-range transport for Sofia have been discussed for two selected periods of few days.
Keywords: CMAQ; wet deposition; model validation; precipitation chemistry data; precipitation adjustment.
Evaluation of local and regional air quality forecasts for London
by Amy Stidworthy, Mark Jackson, Kate Johnson, David Carruthers, Jenny Stocker
Abstract: This paper presents key results from the evaluation of a local-scale air quality forecasting system, airTEXT, alongside the CAMS regional-scale air quality forecast. The CAMS forecast, which is used to account for the long-range transport of pollutants within airTEXT, is adjusted to account for the apparent bias in concentrations predicted within the south-east of England. Forecasts of the UK Daily Air Quality Index metrics for NO2, O3, PM10 and PM2.5 in London have been assessed using the Model Evaluation Toolkit and the DELTA Tool for a five month period during 2017. For NO2, where air pollutant concentrations are primarily a result of local emissions, the local forecast performs significantly better than the regional forecast as the steep roadside concentration gradients are resolved by ADMS-Urban, the dispersion model used within airTEXT. Although regional O3 and particulate forecasts dominate the local forecasts, airTEXT also performs better than CAMS for these pollutants by accounting for emissions, dispersion and chemistry at high spatial resolution.
Keywords: air quality; evaluation; forecast; airTEXT; CAMS; ADMS-Urban.
The coupled chemistry-meteorology model BOLCHEM: an application to air pollution in the Po valley, Italy, hot spot
by Rita Cesari, Tony Christian Landi, Alberto Maurizi
Abstract: We present the model performance of the online air quality model BOLCHEM on seasonal period in an air pollution hot spot. The simulation domain is Northern Italy where a large amount of agricultural, livestock and industrial activities are present, together with big cities such as Milan, Turin and Bologna. Simulations of dispersion and chemical transformation of air pollutants, in both gas and particulate phases, are performed for the year 2010. Simulated surface concentrations of particulate matter (PM10 and PM2.5) are compared with measured concentrations at Airbase Stations for winter period, while for the summer period also ozone (O3) is considered. Only data of background stations are used for comparison. Results show that the PM2.5 and PM10 ground concentration is underestimated both in winter and in summer period. In the winter period, the PM2.5 ground concentration is underestimated by 6.5% on average, and the PM10 ground concentration is underestimated by 7.8% on average. In the summer period, the PM2.5 seasonal average ground concentration is underestimated by 0.7% on average, and the PM10 seasonal average ground concentration is underestimated by 20% on average. This suggest that in the summer period the underestimation in the PM10 values can be due to the Saharan dust emissions. The correlation coefficient R is 0.6 for PM2.5 and for PM10 in both seasons. In the summer period the O3 ground concentration is well reproduced, the correlation coefficient R is 0.7.
Keywords: online air quality model; BOLCHEM; air pollution; hot spot; particulate matter; PM10; PM2.5; ozone; Po valley; Italy; air quality modelling.
Evaluation of the NO2 burden within a joint street canyon and tunnel portal micro environment
by Ulrich Uhrner, Raphael Reifeltshammer, Peter Sturm
Abstract: Substantial breaches in NO2 limits in the vicinity of a tunnel portal and street canyon micro-environment provided the motivation for this paper. The impact of portal and surface road emissions was assessed, and mitigation scenarios computed, in order to aid the authorities responsible. Emphasis was placed on detailed emission processing. A unique dataset from nine NO2 monitors located near the portal and within the street canyon was used to evaluate the model approach using a Lagrangian particle model. Good agreement with measurements was obtained using simple NOx/NO2 conversion approaches. The NOx/NO2 concentration pattern is dominated by surface road emissions. A kerbside area of ~30 m in the driving direction is clearly dominated by the portal emissions indicating effective diffusion at the portal. Major uncertainties are related to the interaction of flow and turbulent mixing from ambient atmospheric conditions and traffic, particularly at low wind speed conditions.
Keywords: urban street canyon and tunnel portal micro environment dispersion modelling; validation vs. measurements; model limitations; portal air management mitigation scenario.
A hybrid Eulerian-Lagrangian-statistical approach to evaluate air quality in a mixed residential-industrial environment
by Giovanni Bonafè, Francesco Montanari, Fulvio Stel
Abstract: The aim of this work is to evaluate the air quality in the mixed urban-industrial environment in the city of Trieste, Italy, in particular, PM10 daily exceedances estimated in a residential district close to a large iron production plant.
Owing to the complex orographic context, to the land-sea discontinuity and to the local scale wind regimes, concentration gradients can often be strong. Therefore it can be misleading to rely only on the monitoring network to assess air quality, since some stations may often have a limited spatial representativeness. On the other hand, under some conditions not only local emissions, but also long-range transport of PM10 or gaseous precursors from the Po Valley, cannot be neglected. To take into account all these factors, we used both a Eulerian chemistry-transport model (CTM) to simulate the daily regional background concentrations, and a Lagrangian model (LM) to simulate the local impact of the emissions from the iron production plant (blast furnace, coking plant and casthouse). Firstly, regional scale background concentrations of PM10 were estimated with a data fusion approach, interpolating the observations of the background stations using concentrations simulated by the CTM as a proxy. Secondly, the residuals over the urban stations were interpolated using concentrations simulated by the LM as a proxy. Finally, the sum of background and residuals was compared daily with the 50
Keywords: chemistry-transport model; Lagrangian model; PM10; data fusion.
Effects of traffic emission reduction on urban air quality episode using WRF/CHEM
by Roberto San Jose, Juan Perez, Libia Perez, Rosa M. Gonzalez
Abstract: In this research, traffic emission control measures have been tested in order to reduce the effects of traffic on Madrid (Spain) during an air quality episode with very large NOx concentrations on December 2016. In this episode, three monitoring stations measured concentrations above 250 μg/m3. The meteorology-chemistry model WRF/Chem allows forecasting these effects making very high spatial resolution (1 km) for investigating the effectiveness of emission controls for improving urban air pollution. The simulations are run eight days, leaving the first two days as spin-up period. The last level nesting simulation domain covers a 45 km by 50 km area. It was necessary to develop very detailed emissions inventories with a bottom-up methodology. For traffic emission the traffic flow simulation model SUMO has been applied, using the real traffic counters data, Madrid vehicle fleet distribution and EMEP-CORINAIR Tier 3 methodology and emission factors. The traffic simulation allows knowing the exact number of vehicles in each time and each segment of the street and road of Madrid. The SUMO network file which describes the roads and intersections the simulated vehicles was extracted from OpenStreetMap. The traffic demand is generated using detector data. The base simulation has been compared with data from the Madrid air quality monitoring network. The simulation system reproduces satisfactorily the high NO2 concentrations. Traffic restrictive measures taken on 28 and 29 December 2016 did not contribute substantially to the improvement of air quality in Madrid. Traffic NOx emissions from road transport, specifically from diesel engines, contributed considerably to the episode because the Madrid fleet composition and emissions are dominated by diesel passenger cars and decisions related to these types of vehicles could be more beneficial for air quality and their effectiveness could be evaluated before taking them with the modelling tool presented in this paper.
Keywords: WRF/Chem; SUMO; traffic emission.
A new bottom-up emissions estimation approach for aircraft sources in support of air quality modeling for community-scale assessments around airports
by Saravanan Arunachalam, Brian Naess, Catherine Seppanen, Alejandro Valencia, JoEllen Brandmeyer, Akula Venkatram, Jeff Weil, Vlad Isakov, Timothy Barzyk
Abstract: Transportation infrastructure (including roadway traffic, ports, and airports) is critical to the nations economy. With a growing economy, aircraft activity is expected to grow across the world. In the USA, airport-related emissions, while generally small, are not an insignificant source of air pollution and related adverse health effects. However, currently there is a lack of tools that can easily be applied to study near-source pollution, and explore the benefits of improvements to air quality and exposures. Screening-level air quality modelling is a useful tool for examining urban-scale air quality impacts of airport operations. Spatially-resolved aircraft emissions are needed for the screening-level modelling. In order to create spatially-resolved aircraft emissions, we developed a bottom-up emissions estimation methodology that includes data from a global chorded inventory dataset from the Aviation Environmental Design Tool (AEDT). The initial implementation of this method was performed for Los Angeles international airport (LAX). This paper describes a new emissions estimation methodology for aircraft emissions in support of community-scale assessments of air quality around airports and presents an illustration of its application at the Los Angeles International airport during the LAX 2011/2012 Air Quality Source Apportionment Study.
Keywords: air quality; exposure; airports; aircraft emissions.
RIAT+, an integrated assessment tool useful for air quality planning: an application to the Emilia Romagna region
by Marco Deserti, Michele Stortini, Enrico Minguzzi, Simona Maccaferri
Abstract: Local authorities and national governments use air quality plans in order to identify measures to reduce the harmful effects of air pollution in compliance with the objectives for air quality. This paper illustrates the practical application of the integrated assessment tool RIAT+ in the definition of Emilia Romagna air quality plan (PAIR2020). Emilia-Romagna was the first case study used during LIFE+OPERA project to design and implement the RIAT+ tool answering regional requirements in air quality planning. The tool was designed to help regional decision makers to select optimal air pollution reduction policies that will improve the air quality at minimum cost and to achieve European Union air quality standards. Finally, the emission air quality plan scenario is compared with base case emission scenarios, as well as PM10 concentration, for different emission scenarios.
Keywords: integrated assessment modelling; air quality modelling; decision support; multi-objective optimisation.
Numerical modelling of transient dispersion of air pollution in a perpendicular urban street intersection with detailed inclusion of traffic dynamics
by Jiri Pospisil, Miroslav Jicha
Abstract: In this study, the authors focus on the use of computer modelling for the detailed identification of the dispersion of transient pollutants in an ideal perpendicular intersection equipped with traffic lights. Attention is drawn to the dispersion of general passive scalar (density and diffusivity identical with air) in the ground level of the atmosphere. The modelled crossroad considers two lanes in each direction, in both street canyons. Sidewalks are located on either side of the road. The control points used to monitor air pollution are located on both sides of the road, in the middle of the sidewalk width, at the pedestrian head level (1.5 m above the sidewalk). Passenger cars are considered as the main source of the monitored air pollution in the intersection. Car movement is at the same time a major driving force affecting the air flow in the crossroad area. A model based on an Eulerian-Lagrangian approach to moving objects has been integrated into a commercial CFD software package called StarCD. The inclusion of traffic dynamics is a necessary step for a correct description of dispersion processes. The air pollution concentration fields were obtained from numerical predictions for traffic light switching periods of 60, 90, and 120 s. The correctness of the developed dispersion model was assessed on the base of NOX concentration measurements carried out in a real city intersection with similar geometry and corresponding traffic conditions as in the numerical model.
Keywords: air pollution; intersection; CFD modelling; car movement; traffic lights.
Parameterisation study of chemically reactive pollutant dispersion over idealised urban areas based on the Gaussian plume model
by Zhangquan Wu, Chun-Ho Liu
Abstract: Dispersion of pollutants emitted from vehicles over urban areas largely affects pedestrian-level air quality. Poor ventilation inside street canyons often results in pollutant accumulation, which is harmful to urban inhabitants. Most vehicular exhausts contain chemically reactive compounds that evolve to their secondary counterparts in the atmospheric boundary layer (ABL). Therefore, the conventional Gaussian plume model, which assumes inert pollutants, should be used cautiously. In this study, turbulent dispersion of reactive pollutants in the ABL over hypothetical urban areas in the form of idealised street canyons is investigated using large-eddy simulation (LES). Nitric oxide (NO) is emitted from the first street canyon into the urban ABL doped with ozone (O3). First of all, we make use of the advection-diffusion equation with chemical kinetics to derive the theoretical relation between the dispersion coefficients of tracer and reactive pollutants. Next, the source depletion analogy is used to determine the plume shape instead of the conventional Gaussian plume model. Finally, regression to the LES output reveals that the vertical dimensionless NO concentration profiles exhibit self-similarity for a range of background O3 concentrations. A new parameterisation of reactive plume dispersion over urban areas, whose performance is remarkable over the mean plume rise, is thus suggested. The discrepancy in the near-wall region is caused by the non-uniform mean wind speeds and the dominated NO oxidation.
Keywords: Gaussian plume model; hypothetical urban areas; large-eddy simulation; ozone titration; reactive nitric oxide plume transport.
Air exchange in urban canyons with variable building width: a numerical LES approach.
by Michela Garau, Maria Grazia Badas, Simone Ferrari, Alessandro Seoni, Giorgio Querzoli
Abstract: The aim of this work is to gain further insight into the role played by the building aspect ratio (ARB, i.e. the ratio of the building width, WB, to the building height, H) and its influence on street canyon flow. We carried out a series of Large Eddy Simulations (LES) with arrays of obstacles with different widths, ranging from 0.5 to 2.0, and two canyon aspect ratios (ARC, i.e. the ratio of the canyon width, W, to H) ARC = 0.5 and ARC = 1.0. Experimental data was obtained in a water channel for the corresponding configuration and used to validate numerical simulations. Results were found strongly dependent on the building aspect ratios, with two distinct behaviours identified with respect to the canyon aspect ratio. The residence time decreases with decreasing ARB, irrespective of the canyon aspect ratio, suggesting that ARB and ARC can be optimised to guarantee an optimal street canyon ventilation in urban planning.
Keywords: urban street canyon; large eddy simulation; flow exchange rate; building aspect ratio.
CFD studies of pollutant spatial distribution in a large office
by Nektarios Koutsourakis, John Bartzis, George Efthimiou, Ioannis Sakellaris
Abstract: One of the goals of research on indoor air quality is the reduction of human exposure to the dispersion of hazardous airborne materials. The purpose of this study is to analyse, by using Computational Fluid Dynamics (CFD), the flow and the concentration patterns of floor-emitted pollutants inside a real, mechanically ventilated office of simple geometry. The simulation results show complex airflow and high heterogeneity of concentration distribution. Another objective of the study is to examine how alternative ventilation scenarios (vents position and flow strength) could affect the human exposure in the same office. Furthermore, additional simulations and sensitivity tests are performed in order to discuss CFD reliability issues. Studies like this contribute to the determination of the parameters that influence the modelling results and prepare the ground for improved and more reliable future simulations of indoor pollutant dispersion.
Keywords: computational fluid dynamics; CFD; indoor air quality; IAQ; offices; complex flow; pollutant dispersion; concentrations’ heterogeneity; ventilation optimization; simulation reliability; modelling parameters; ADREA.
Evaluation of OpenFOAM against CODASC wind tunnel database and impact of heating on the flow in an idealised street canyon
by Anton Petrov
Abstract: This paper focuses on examination of the impact of an irregularly heated surface on the flow recirculation and pollutant distributions in a tree-free idealised street canyon. For this purpose, the buoyant BoussinesqPimpleFoam solver of the CFD model OpenFOAM was tested against the CODASC wind tunnel database (http://www.windforschung.de/CODASC.htm). The wind tunnel experiments were run only under neutral atmospheric stratification conditions, so in order to examine the impact of the heating on the flow, OpenFOAM was set for two general cases. In the first one, the model was run with initial conditions that correspond to the physical conditions in the wind tunnel. The simulated data is then compared with that measured in the tunnel. For the second case, an additional boundary condition for the air temperature near the surface of the street canyon was set. An intercomparison of the modelled data from both cases is then made.
Keywords: street canyon; computational fluid dynamics; urban pollution; OpenFOAM; dispersion modelling; heat impacted flow; model evaluation; wind tunnel; CODASC.
Emission projections and limit values of air pollution concentration: a case study using the EMEP4PL model
by Małgorzata Werner, Maciej Kryza, Kinga Wałaszek
Abstract: In this study, we applied the EMEP/MSC-W model at a high spatial resolution of 4 km x 4 km over Poland (EMEP4PL), and ran the model for the whole of the years 2015 and 2030. For the second simulation we used GAINS PRIMES emission projection and kept the meteorology from 2015. Although the model results are satisfactory and comparable with the results in other European countries, the number of days with exceedances of the limit value is highly underestimated in comparison with observations for 2015. It shows that the model is limited in its simulation of very high particulate matter concentrations in the winter season. Therefore, we applied a bias correction for the year 2030 based on the observations and model results for the year 2015. Bias corrected simulation shows that at 60 stations (out of 104), the PM10 daily limit value will be exceeded at least 35 times in 2030.
Keywords: particulate matter; EMEP4PL; emission projections; limit values.
On the comparison of urban canopy effects parameterisation
by Tomas Halenka, Michal Belda, Peter Huszar, Jan Karlicky, Tereza Novakova, Michal Zak
Abstract: To assess the impact of cities on climate, a modelling approach is often used with inclusion of urban parameterisation in a land-surface scheme. This is important when applying higher resolution, which is a common trend in atmospheric modelling. Because adaptation and mitigation measures are often applied in the big cities, it is essential to assess the uncertainty of the parameterisation of urban effects. We contribute to the estimation of this uncertainty by performing experiments with available settings of urban canopy models, to assess urban canopy meteorological forcing over central Europe for 2001-2010. We have used RegCM4 and WRF in 10 km resolution, three surface schemes (BATS and CLM4.5 for RegCM4 and Noah in WRF) and five available urban canopy parameterisations: one bulk urban scheme (WRF), three single layer schemes (both RegCM and WRF) and a multilayer urban scheme (WRF). A few WRF options are tested for urbanised weather prediction in 3 km resolution as well to show the effect in a single, but quite extreme, case study. An urban heat island was detected clearly in all the simulations, for summer night the strongest on average of a few
Keywords: urban heat island; urban parameterisation; regional climate models; extreme events; heat waves.
Effects of increasing the surface reflectance over air quality levels using WRF-BEM/AEMM/CMAQ: an application over the city of Madrid
by Mª Ángeles González, Raúl Arasa, Pedro Gámez, Miquel Picanyol, Pablo Campra
Abstract: The effects of increasing the surface reflectance by albedo modifications have been evaluated using an air quality modelling system. We have evaluated the influence over pollutant concentrations of increasing from 0.20 to 0.55 the roof surface albedo (scenario called Albedo1) and increasing from 0.15 to 0.30 the ground surface albedo and from 0.20 to 0.55 the roof surface albedo for all urban categories (scenario called Albedo2). To obtain a better representation of the local processes we have considered very high resolution (333.33 m) and up to 10 different urban categories. Changes in albedo cause changes in different meteorological parameters (planetary boundary layer height, radiation and temperature), modifying the pollutant concentration in every single scenario. Results show that this mitigation measure is effective during summer periods, providing not high NO2 increments and O3 reduction on the urban areas of the city of Madrid. During winter periods the measure induces NO2 increments over polluted areas with high NOx emissions. In this way, the benefits of the measure, from the point of view of urban heat island effects, are greater than the detriments during summer periods, in comparison with air quality effects.
Keywords: BEM; CMAQ; urban albedo; air quality; Madrid city; cool roof.
Validation of dispersion models using Cabauw field experiments and numerical weather re-analysis
by Gertie Geertsema, Marko Kaasik
Abstract: The Gaussian atmospheric dispersion model AEROPOL is validated against the classical Cabauw dispersion experiment, driven by (1) on-site meteorological data and (2) meteorological data from the numerical weather model HARMONIE. The meteorological forecast time used at the time of the release is 10 to 14 hours ahead of the analysis time. The results from the combination of AEROPOL with on-site data are slightly better than with re-analysed meteorology. The near-surface concentrations based on the combination of AEROPOL with the model forecasts are in general lower than the concentrations from the combination of AEROPOL with on-site data and are also lower than the observed concentrations. The combination of AEROPOL with meteorological model results in a mismatch between the modelled position of the plume axis with the observed plume axis. The results show a significant improvement in the HARMONIE version 38 with respect to the HARMONIE version 37.
Keywords: Cabauw dispersion experiment; HARMONIE; AEROPOL; HARMO initiative; model validation.
Modelling nitrogen deposition: dry deposition velocities on various land-use types in Switzerland
by Sebnem Aksoyoglu, André S. H. Prévôt
Abstract: In this study, we analysed nitrogen deposition in Switzerland obtained from a modelling study in Europe for 2006 with the CAMx model. Comparison of modelled ammonia with measurements showed a relatively good agreement for annual concentrations whereas an overestimation was found in spring due to the meteorological conditions prevailing in 2006. The modelled average annual nitrogen deposition of 12.2 kg N ha-1 a-1 in Switzerland was dominated by the deposition of reduced nitrogen compounds (74%) and the largest contribution to nitrogen deposition was from dry deposition of ammonia. Dry deposition velocities of oxidized and reduced nitrogen compounds were calculated for specific land-use types found in Switzerland. The highest annual deposition velocities for ammonia and nitric acid were estimated over evergreen shrubs whereas the deposition was lowest over water surfaces. Deposition velocities over various land surfaces were shown to vary seasonally and the values in spring and summer were higher than in winter by a factor of up to 2.7.
Keywords: nitrogen; ammonia; dry deposition velocity; reduced nitrogen; oxidised nitrogen; land-use; evergreen shrubs; seasonal variation; CAMx; Switzerland.
Special Issue on: Dioxins, Sources and Effects, Formation and Abatement
GC-HRMS analysis for POPs and new POPs with GC-Tof/MS techniques
by Takumi Takasuga