International Journal of Environment and Pollution (39 papers in press)
Simulating large emitters using CMAQ and a local scale finite element model: analysis of the surroundings of Barcelona
by Albert Oliver, Raul Arasa, Agusti Pérez-Foguet, Mª Ángeles Gonzalez
Abstract: In this work, we present a novel approach to simulate large emitters on the microscale. The main idea is to combine a nested grid approach and a finite element model to simulate the subgrid scale. The nested grid system consists of the mesoscale meteorological model WRF-ARW, the Air Emission Model of Meteosim (AEMM), and the air quality model CMAQ. The subgrid scale is simulated using an adaptive, Eulerian, non-steady finite element model. The results from the nested grid simulation are used as initial and boundary conditions in the subgrid model, making this approach one-way. A simulation has been carried out in the surroundings of Barcelona, where an important contributor to the sulphur dioxide levels is considered. The simulations were carried out for one episode with high levels of sulphur dioxide. The time period of the simulation was 48 hours with a 24-hour spin-up.
Keywords: AQM; air quality modelling; subgrid scale plume modelling; nested
grid modelling; dispersion models; large emitters; local scale; microscale;
plume rise; WRF; weather research & forecasting model; AEMM; air emission
model of Meteosim; CMAQ; community multi-scale air quality; FEM; finite
element method; PinG; plume-in-grid; one-way nesting; Barcelona; forecasting;
Lagrangian simulations of the plume rise in strong capping inversion
by Enrico Ferrero, Stefano Alessandrini, Domenico Anfossi
Abstract: We have performed new investigations applying our Lagrangian algorithm described by Alessandrini et al. (2013) to simulate the plume rise in a convective boundary layer capped by a strong inversion layer. We tested our model with the results of a water tank experiment (Weil et al. 2002). For each case, we compared the simulated and measured mean height, horizontal and vertical plume standard deviations, and the entrapment (the fraction of the plume that remains captured above the temperature inversion layer located at the top of the boundary layer). The results show that the model is able to reproduce the main characteristics of the plume accurately.
Keywords: Lagrangian model; plume rise; entrapment.
Aspects of carbon dioxide mitigation in a closed microalgae photobioreactor supplied with flue gas
by Eyal Kurzbaum, Anat Aharoni, Felix Kirzhner, Yossi Azov, Thomas Friedl, Robert Armon
Abstract: The aim of the present study is to investigate the potential of flue gases to be efficiently and economically applied in production of algal biomass in a photobioreactor (PBR). Various microalgae strains (Chlorella sorokiniana 211-34, Bracteacoccus minor 61.80, Radiosphaera negevensis 87.80, Chlorosarcinopsis negevensis 67.80 and Chlorococcum novae-angliae 5.85) have been tested for CO2 mitigation, growth and tolerance to high CO2 levels. The flue gas and CO2 bubbling induced a significant algal mass growth compared to control (ambientair). Removal of CO2 and NO by the studied microalgae strains was found to be 44% and 33% along daily intervals, respectively. A growth rate of ~0.4g L-1 d-1 was obtained for all algal species tested. Growth conditions for tested algae can be optimied through PBR technology in order to obtain the highest biomass yield for production of valuable biochemicals (i.e. low-cost biofuel).
Keywords: carbon dioxide; flue gas; photobioreactor; microalgae; biomitigation; algae; nitric oxide; growth rate.
Screening and characterisation of a poly(vinyl alcohol)-degrading mixed microbial culture
by Jie Zhang, Ying Zhang, Xuerong Fan, Ping Wang, Artur Cavaco-Paulo, Qiang Wang
Abstract: A mixed microbial culture, which can degrade poly(vinyl alcohol) (PVA), was screened from the activated sludge of a textile factory. This mixed culture was found to consist of many bacterial strains, including representatives of Pseudomonas, Sphingopyxis, Castellaniella, Stenotrophomonas, Ochrobactrum and Shinella. The relative abundance of strains in the mixed culture during the incubation period was determined through the Illumina Miseq Platform. The biodegradation of PVA by this mixed culture in liquid medium was determined using several methods, including UV and gel-permeation chromatography. When the mixed culture was incubated in PVA1799-containing mineral medium for 4.5 days, the concentration of PVA decreased by 91% and the mean weight-average molecular weight of PVA decreased by 68%. The PVA-degrading enzymes produced by the mixed culture appear to be membrane or intracellular enzymes. The optimum pH and temperature for PVA-degrading enzyme activity were investigated by single-factor tests and were discovered to be pH 7.0 and 40 oC, respectively. The crude enzymes extracted from the mixed culture could partly degrade PVA1799 nanofibre scaffold.
Keywords: poly(vinyl alcohol); biodegradation; mixed microbial culture; nanofibre scaffold; PVA-degrading enzyme.
EDTA and citrate impact on heavy metals phytoremediation using Paulownia hybrids
by Maria Geneva, Kameliya Miladinova-Georgieva, Katya Ivanova, Teodora Georgieva, Petar Petrov, Ira Stancheva, Yuliana Markovska
Abstract: The influence of the EDTA and citrate addition to the industrially polluted soil on phytoextraction of heavy metals, leaf anatomy, and gas exchange parameters of two Paulownia hybrid lines (Paulownia tomentosa x fortunei - TF 01 and Paulownia elongata x fortunei - EF 02) was evaluated. Both lines were accumulators of Cu, Zn and Cd because bioaccumulation factor values were higher than 1.00. The levels of heavy metal accumulation in shoots indicated that both hybrids may be used for phytoremediation, since transfer factors for Pb and Zn in hybrid TF 01 were higher than 1.00, and in hybrid EF 02 for Zn only. Application of EDTA produced heavy metal accumulation in hybrid lines higher than those obtained with citrate. Treatment with 1 mM EDTA displayed a protective effect on leaf development in both lines and overcame damage in the morphological structure caused by heavy metal stress
Keywords: Paulownia elongata x fortunei - EF 02; Paulownia tomentosa x fortunei - TF 01; phytoextraction; mesophyll thickness; gas exchange.
Assessment of ambient air quality around mines, in buffer zone and along ore transportation routes in iron ore mining region of Goa: emphasis on spatial distributions and seasonal variations
by Gurdeep Singh, Atahar Perwez
Abstract: Monitoring was done with respect to PM10, PM2.5, SO2 and NOX at 34 stations selected in mines, buffer zone and along ore transportation routes. Particulate pollutants (PM10 and PM2.5) were observed as the major pollutants in the study area, and ore transportation was identified as the most polluting activity. The calculated values of AQI also evidenced the same. The concentrations of PM10 and PM2.5 along the ore transportation routes were observed as 130
Keywords: ambient air quality; assessment; air quality index; ANOVA; correlation; mining; NOX; PM10; PM2.5; ratio; SO2; transportation routes.
Dioxin emission from some metallurgical processes
by Grzegorz Wielgosinski, Patrycja Lechtanska, Adam Grochowalski, Mariusz Holtzer, Wlodzislaw Cwiakalski
Abstract: Results of the measurements of emissions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in two metallurgical plants representing ferrous metallurgy (iron ore sintering plant) and non-ferrous metallurgy (secondary copper smelter) are discussed. In the case of the secondary copper smelter, dioxin concentrations were determined in the range from 0.03 to 8.1 ng TEQ/Nm3, and high variability of emissions was observed that depended on both the material fed and the stage of smelting. In the case of measurements in the iron ore sintering plant, the concentrations ranged from 0.6 to 1.7 ng TEQ/Nm3. It was found additionally that a well functioning electrostatic precipitator could reduce PCDD/Fs emission by up to 75% (with respect to the total mass of congeners), and off-gas recirculation had no significant effect on emissions
Keywords: dioxin emission; PCDD/Fs; secondary copper smelter; iron ore sintering plant.
Eutrophication research of Dongting Lake: an integrated ML-SEM with neural network approach
by Xaodong Li, Zhihua Gao, Zuo Chen, Guangming Zeng, Tomás León, Jie Liang, Fei Li, Wu Liu, Haipeng Wu, Chungyan Du, Ren Chen
Abstract: It is pressing to investigate the influencing factors of eutrophication in Dongting Lake, which is the second largest freshwater lake in China and is faced with more and more serious eutrophication problems by natural and man-made factors in recent years. In this study, a new multivariate analysis approach integrating the maximum likelihood estimation structural equation modelling (ML-SEM) with neural network method was proposed. Twenty-seven variables indicating water quality from 2005 to 2012 were derived from the Dongting Lake Ecological Environment Monitoring Center of Hunan Province. The results showed that: (1) temperature (T) and hydraulic gradient (HG) had the most positive influences on chlorophyll-a (Chl-a) with a sensitivity ratio of 1.218 and 1.039, respectively; (2) transparency (SD) had the most negative effect on Chl-a concentration; (3) Chl-a increased quickly and reached the highest level when total phosphorus (TP) levels were from 0.08 mg/L to 0.12 mg/L. These results will be basic information for eutrophication control strategies in Dongting Lake. By combining ML-SEM with artificial intelligence techniques, such as neural network, this study examined the causal and non-linear relationships involved in the eutrophication process.
Keywords: eutrophication; modelling; SEM; neural network; Dongting Lake.
Estimation of biocovers surface fluxes by two tools under Canadian atmospheric real conditions
by Abderrahim Lakhouit
Abstract: In order to investigate the reduction of greenhouse gases by novel and ecological bio-processes, three passive methane oxidation biocovers (PMOB) were installed in St Nicephore landfill in Quebec, Canada. The aim of the present paper is to estimate surface fluxes of volatile organic compounds (VOC) using two different direct measurement methods. Rectangular and circular flux chambers were used to collect the emitted biogas at the surface of the PMOBs. The sampling period took place from June to September 2012. An analytical method was developed to analyse the landfill biogas. Gas ChromatographyMass Spectrometry (GC/MS) and SolidPhase MicroExtraction (SPME) fibre were used to identify and quantify VOCs. A number of VOCs were identified and quantified in landfill biogas. During the present study, more attention was given to benzene, toluene, ethylbenzene, and xylene (known in the literature as BTEX) surface fluxes. The surface emission fluxes varied from 182.5 μg/m2/year to 3.8 mg/m2/year.
Keywords: surface fluxes; biocover; volatile organic compounds; BTEX.
Multielement sorption of cadmium, zinc, copper and lead onto a Fluvisol profile at Stara Loza site, Croatia
by Stanko Ružičić, Teo Rako
Abstract: The subject of this study is the Fluvisol profile, developed in the Stara Loza water wellfield area of the Zagreb aquifer. The main objectives of the investigation were: (1) to determine the sorption characteristics of lead, zinc, copper and cadmium using a batch experiment, and (2) to build potentially toxic metals (PTMs) isotherms in soil horizons of Fluvisol. The soil texture is silt loam of a light yellow colour, and granular structure. The pH values of the soil vary from 7.97 to 8.38. Cation exchange capacity (CEC) has higher values in the first three horizons. Based on the results of the experiment, linear sorption isotherms were created for all the soil horizons. Freundlich distribution coefficients are determined from sorption isotherms, and the sequence is Pb>Cu>Cd>Zn. The comparison of sorption isotherms has determined that the lead has the best sorption in the soil. Sorption of potentially toxic metals is decreasing with depth.
Keywords: sorption; Fluvisol; potentially toxic metals.
Identification of a dynamical model for phytoplankton bloom based on high frequency measurements
by Hafiz Ahmed, Rosane Ushirobira, Denis Efimov, Wilfrid Perruquetti
Abstract: High frequency measurements of various water characteristics and nutrients information of the Marel-Carnot sea monitoring station (Boulogne-sur-Mer, France) have been used to identify a physiological model for phytoplankton bloom through the fluorescence signal. An auto-regressive-moving-average with exogenous inputs (ARMAX) model is designed and tested based on the dataset. The model takes into account the effect of the measured water characteristics and nutrient level information. Through this study, it is demonstrated that the developed dynamical model can be used for estimating the fluorescence level (which characterises the phytoplankton biomass) and for predicting the various states of phytoplankton bloom. Thus, the developed model can be used for monitoring phytoplankton biomass in the water which in turn might give information about unbalanced ecosystem or change in water quality.
Keywords: model identification; phytoplankton bloom; ARMAX model.
Using 137Cs and 210Pbex to quantify the effects of land use on soil organic carbon and total nitrogen in the subtropical Dianchi watershed, southwest China
by Mingli Zhang, Xia Wang, Biao Xie, Yong Zhang
Abstract: The conversion from forest to agricultural land in the last three decades represents a significant shift in land use in China. However, few direct measurements have been made to investigate the dynamic processes of soil organic carbon (SOC) and total nitrogen (TN) under land use change. Our results showed that converting forest to grassland and farmland led to an increase in SOC content, and decreases of TN concentration and C:N ratio in the topsoil. The erosion rate and nutrient loss estimated by 137Cs showed highest under farmland. The highest nutrient losses were found in cultivated farmland, with 4.08 and 0.40 t km-2 year-1 for SOC and TN, respectively. We conclude that forest system could be an effective strategy to improve SOC stocks in the subtropical Dianchi watershed. The accumulation of nitrogen in cultivated farmland soils poses a potential threat to nearby Dianchi Lake.
Keywords: soil organic carbon; total nitrogen; C:N ratio; 137Cs and 210Pbex; Dianchi watershed.
Special Issue on: Dioxins, Sources and Effects, Formation and Abatement
Surface catalysed PCDD/F formation from precursors: high PCDF yield does not indicate de novo mechanism!
by Slawo Lomnicki, Shadrack Nganai
Abstract: Our present studies reinforce the thesis that it is the ratio of chlorinated benzenes to chlorinated phenols that determines the PCDD to PCDF ratio (D/F). We report the results of a PCDD/F formation over iron oxides from of a mixture of 2-MCP and 1,2-DCBz with a varying gas phase composition. We have found that the competitive adsorption between the chlorinated benzenes and chlorinated phenols affect the overall precursor transformation and play a crucial role in the PCDD/F formation mechanism in mixed streams. Chlorophenols adsorb more readily on the iron oxide surfaces and undergo faster transformations. In both pyrolytic and oxygen-rich conditions the formation of PCDD products is a function of the content of 2-MCP in the feed stream. For pyrolysis the highest conversion into PCDDs was observed at 90% 2-MCP and 10% 1,2-DCBz stream composition. In oxygen-rich conditions, PCDF yields were the highest between 90-50% 2-MCP content stream. Comparing integrated PCDD and PCDF yields, it becomes apparent that, with decreasing 2-MCP content in the feed stream, PCDF formation yield is increasing and levels off at ~0.4% for pyrolytic and ~0.6% for oxidative conditions. PCDDs, on the other hand, are formed with the highest yield at 90% of 2-MCP content in the feed stream, and decrease to undetectable for pure 1,2-DCBz stream. Present results further confirm that the D/F ratio cannot be used to validate the de novo pathway or as an indicator of the de novo reaction in the incinerators. In fact, the D/F ratio is most strongly dependent on the relative concentration of precursor groups in the reaction stream chlorinated benzenes vs chlorinated phenols.
Keywords: PCDD/F; dioxin/furan ratio; precursor model; iron oxide.
Simultaneous control of polychlorinated dibenzo-p-dioxins/dibenzofurans, polychlorinated biphenyls, and nitrogen oxide in flue gas using urea
by Masaki Takaoka, Madoka Nakamura, Kazuyuki Oshita, Yoshihiro Nishimoto, Hitoshi Harada, Hiroki Fujihira
Abstract: To improve heat recovery and electrical power generation at municipal solid waste incinerators, a new flue gas treatment system, which includes a ceramic filter for dust removal at 300
Keywords: Ceramic filter; heat recovery; inhibition; low air ratio; municipal solid waste incinerator; nitrogen oxide decomposition; polychlorinated biphenyl; polychlorinated dibenzofuran; polychlorinated dibenzo-p-dioxin; urea.
GC-HRMS analysis for POPs and new POPs with GC-Tof/MS techniques
by Takumi Takasuga
Catalytic oxidation of 1,2-DCBz over V2O5/TiO2-CNTs catalysts: the effect of water
by Cuicui Du, Shengyong Lu, Qiulin Wang, Alfons Buekens
Abstract: A series of vanadium oxide catalysts, supported on a titanium dioxide (TiO2)-carbon nanotubes (CNTs) carrier, was prepared. The purpose was to study the catalytic oxidation of 1,2-dichlorobenzene (1,2-DCBz) during tests featuring a variable moisture content (0~5% water) in the combustion air. The concentration of water vapour greatly influences the constitution of the catalytic surface and thus considerably affects the reactivity of V2O5/TiO2-CNT catalysts. A strong promoting effect was observed when feeding air with 1 vol. % of moisture, possibly owing to the formation of more active surface hydroxyl groups, an increased average oxidation state of vanadium (Vaos) and reduced carbon and chlorine accumulation on the catalytic surface. Addition of 5% moisture, however, evidently reduced reactivity, mainly owing to the competitive adsorption of water and 1,2-DCBz. The V2O5/TiO2-CNT catalysts were more obviously sensitive to humidity than the V2O5/TiO2 catalysts.
Keywords: catalytic oxidation; carbon nanotubes; 1,2-dichlorobenzene; water; functional groups.
Comparison and relationship of polychlorinated dibenzo-p-dioxins and dibenzofuran levels between stack gas and fly ash samples from waste incinerators
by Rong Jin, Yuyang Zhao, Guorui Liu
Abstract: In this study, the relationship between polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) in stack gas and fly ash phases was investigated to evaluate if the exchange of PCDD/F congeners between the two media would affect PCDD/F characteristics. The concentration, congener profile of PCDD/F and ratios of PCDDs to PCDFs in stack gas and fly ash were compared. Spearman correlations between lower chlorinated congeners in fly ash and congeners in stack gas were significant, suggesting that lower chlorinated congeners were prone to exchange between the two phases. However, Spearman correlations of the other PCDD/F congeners between stack gas and fly ash were not significant, indicating exchange of these PCDD/F congeners between the two phases was minimal.
Keywords: polychlorinated dibenzo-p-dioxins and dibenzofuran; waste incinerator; correlation analysis; congener profile; stack gas; fly ash.
Decomposition of trace chlorobenzene over V2O5WO3/TiO2-based catalysts in simulated flue gas
by Shengyong Lu, Chunwai Lee, Brian Gullett, William Stevens, Yongxin Zhao, Rixiao Zhao
Abstract: Commercial and laboratory-prepared V2O5WO3/TiO2-based catalysts with different compositions were tested for catalytic decomposition of chlorobenzene (ClBz) in simulated waste combustion flue gas. Resonance-enhanced multiphoton ionisation-time of flight mass spectrometry (REMPI-TOFMS) was employed to measure real-time trace concentrations of ClBz contained in the flue gas before and after use of the catalyst. The results showed that the ClBz decomposition efficiency was significantly enhanced when nano-TiO2 instead of conventional TiO2 was used as the catalyst support. No promotion effects were found in the ClBz decomposition process when the catalysts were wet-impregnated with CuO and CeO2. A comparison between ClBz and benzene decomposition on the V2O5WO3/TiO2-based catalyst and the relative kinetics analysis showed that different active sites were likely involved in the decomposition mechanism, and the V=O and V-O-Ti groups may only work to catalyse the degradation of the phenyl group and the benzene ring rather than the C-Cl bond.
Keywords: chlorobenzene; V2O5–WO3/TiO2; catalyst; REMPI-TOFMS; decomposition.
Mechanochemical treatment of hexachlorobenzene: effect of additives
by Qiongjing Mao, Shengyong Lu, Zhiliang Chen, Buekens Alfons, Jianhua Yan
Abstract: Mechanochemical (MC) methods have shown an excellent performance while decomposing a number of halogenated persistent organic pollutants (POPs). Selected milling equipment was used to treat the contaminated materials. To exploit this MC technology, it is also essential to develop appropriate effective and economic additives, acting as a reducing agent and accelerating the rate of POPs decontamination. In this study, a number of MC degradation tests were performed on hexachlorobenzene, using an all-dimensional planetary ball mill and applying selected additives, including CaO, CaO-SiO2, CaO-Al2O3, CaO-Al (metal) and Fe-SiO2 (under N2). After 8 h of milling, up to 99.7% of the original HCBz was removed by processing with a combined CaO-Al additive and 95.3% of the chlorine present was water-soluble. Different ratios of Al to CaO were compared and the highest (99.70%) destruction efficiency of HCBz was achieved already after 3 h by the additive CaO-Al (11.1% added), considered to be the most economic and practical pair. Sequential dechlorination of HCBz and polymerisation of the resulting residue benzene should be the main degradation pathway; this conclusion is reached by observing lower chlorinated chlorobenzene intermediates (PeCBz, 1,2,4/1,3,5-TrCBz, and 1,2-DCBz) and graphite and amorphous carbon as final products. Chloride salts, i.e. CaCl2 and AlCl3 are also amorphous end-products. Strong radical signals and micro-spheres as well as tribo-microplasma phenomena were induced by severe mechanical ball milling. The additive pair CaO-Al proved to be a highly effective combination for HCBz degradation, and this study will be completed by applying mechanochemical treatment on other halogenated POPs, including dioxins.
Keywords: mechanochemistry; hexachlorobenzene; CaO-Al additives; ball mill; degradation; mechanism.
Special Issue on: HARMO17 Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes
Evaluation of some blood parameters in parallel with expression of P53 and IL-6 in industrial pollution exposed subject
by Hadis Ahmadirad, Mohammad Reza Hajizadeh, Gholamhossien Hassanshahi, Mehdi Mahmoodi
Abstract: Industrial pollution, including trace elements, has the ability to cause cancer and inflammatory diseases in humans. Therefore, this study was aimed to determine inflammatory and cancer biomarkers, such as P53 and IL-6, in parallel with some other blood biochemical parameters in normal subjects and people who were exposed to industrial trace elements. The studied population included 45 workers who were exposed to trace elements and 45 control group members. Blood biochemical parameters such as CBC were examined by cell counter, and gene expression of P53 and IL-6 was detected by real time PCR technique; liver enzymes were also measured by a Hitachi 912 analyser. Our findings showed that the gene expression IL-6 (as an indicator of inflammation) was significantly increased in workers who were exposed to pollution, and P53 was also considerably increased (as an indicator of DNA damage). The levels of liver enzymes SGOT and SGPT, along with the number of both red blood cells and white blood cells, were also increased; however we observed no significant changes in these factors. The results showed that the exposure to industrial pollution leads to increased expression of P53 and IL-6. This evidence may confirm a potential role for pollution and trace elements in developing inflammatory diseases and cancer in workers.
Keywords: industrial pollution; trace elements; IL-6; p53.
Model intercomparison and validation of ADMS plume chemistry schemes
by Stephen Smith, Jenny Stocker, Martin Seaton, David Carruthers
Abstract: Two schemes for the determination of NO2 concentrations in the atmospheric dispersion model ADMS are evaluated using data from two sites in Alaska. Both schemes take account of the rate of oxidation of NO and photolysis of NO2 in the plume using identical chemical formulations. The differences lie in the approaches used for the entrainment and mixing of ambient ozone into the plume. In the standard scheme it is assumed that ozone is mixed instantaneously into the plume at source; in the entrainment limited scheme ozone is entrained into the plume at a rate determined by the rate of dilution of the instantaneous plume. A methodology comprising a scatter plot of the ratio of modelled to observed NO2 vs. modelled to observed NOx is used to distinguish errors in the chemistry schemes from errors in the prediction of NOx. Both schemes show good performance statistics with the standard scheme predicting higher NO2 concentrations.
Keywords: plume chemistry; nitrogen dioxide; ADMS; validation; model intercomparison.
Special Issue on: Dioxins, Sources and Effects, Formation and Abatement Part 2
Oxidation of 4-bromo-4-chlorobiphenyl, model species for forming mixed halogenated aromatic compounds
by Song Hou, Bogdan Z. Dlugogorski, John C. Mackie, Eric M. Kennedy, Stina Jansson, Mohammednoor Altarawneh
Abstract: This contribution reports results from the gas-phase oxidation of 4-bromo-4-chlorobiphenyl (4,4-BCB) in order to fathom the formation of toxic species produced during the combustion of mixed halogenated aromatics. In their own right, mixed polybrominated/polychlorinated biphenyls (PXBs) represent a new class of environmental contaminants, recently detected in food and human tissues. Gas chromatography-quadrupole mass spectrometry (GC-QMS), gas chromatography-quadrupole time of flight mass spectrometry (GC-QTOFMS), Fourier transform infrared spectroscopy (FTIR) and ion chromatography (IC) served to analyse the volatile and semi-volatile organic compounds (V/SVOCs), including mixed halogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs), and gaseous products including HBr/HCl. The selection of non-ortho-substituted PXB as a model species yields a large number of halogenated compounds, including monochloro- and monobromo-benzene and higher halogenated benzenes and naphthalenes, and derivatives of halogenated benzenes (such as 1-chloro-4-ethynylbenzene). We also detect small amounts of chlorinated and mixed halogenated dibenzofurans. The present study provides insights into the formation of several classes of halogenated and mixed-halogenated pollutants in combustion processes involving both bromine and chlorine sources, such as those of brominated flame retardants and PVC plastics.
Keywords: biphenyl; BFRs; dioxins; DFT.
Special Issue on: HARMO 17
Influence of vehicle-induced turbulence on pollutant dispersion in street canyon and adjacent urban area
by Jiri Pospisil, Miroslav Jicha
Abstract: This paper presents an assessment of the influence of turbulence intensity in the close vicinity of a linear source of pollution on the consequent process of air pollutant dispersion in an urban environment. Turbulent flow structure in the vicinity of vehicles in motion significantly influences the dispersion of air pollution generated by road traffic into the environment of a traffic path. Higher turbulence intensity results in a greater mixing of air. The detailed investigation of cross-section vortex in the street canyon is done by a computational parametric study. Pollutant dispersion is monitored at a specific segment of an urban area crossed by a straight traffic path. The traffic path represents a studied linear source of pollution. The motion of vehicles along the traffic path has been considered as an input parameter for the consequent quantification of the kinetic energy of turbulence generation above the traffic path. The influence of generated kinetic energy of turbulence by linear road on the concentration of PM10 at receptor points located in the studied area is obtained by using the mathematical modelling method CFD. Assessment of the results gained defines a relation between the PM10 concentration at a ground-layer of air and the kinetic energy generated by a linear source.
Keywords: air pollution; modelling; kinetic energy of turbulence; PM10; dispersion; cars.
Application of a photochemical model for the assessment of regional air quality in southern Italy: procedures and results
by Annalisa Tanzarella, Ilenia Schipa, Angela Morabito, Camillo Silibello, Roberto Giua, Giorgio Assennato
Abstract: A modelling system based on FARM chemical transport model is applied to assess the air quality (AQ) over the Apulia region (Southern Italy) for 2013. The most relevant pollutant sources in the region are a steel plant, the largest in Europe (in the Taranto area), a coal-fired power plant, the second most powerful in Italy (in the Brindisi area) and biomass burning for residential heating. Simulation results evidence exceedances for PM10 daily limit value and benzo(a)pyrene annual limit values occurring in some areas. The evaluation of the model performance has been conducted by using the software DELTA Tool, developed within FAIRMODE to support the application of the EU Air Quality Directive. Results show good performance of the model, with a tendency to underestimate PM10 and ozone levels. These results suggest to use this modelling strategy for further source apportionment studies, in order to identify the sources that mainly affect air quality and to implement proper emission control strategies.
Keywords: air quality assessment; photochemical model; model evaluation tool.
Evaluation and development of tools to quantify the impacts of roadside vegetation barriers on near-road air quality
by Vlad Isakov, Akula Venkatram, Richard Baldauf, Parikshit Deshmukh, Max Zhang
Abstract: Traffic emissions are associated with the elevation of health risks of people living close to highways. Roadside vegetation barriers have the potential of reducing these risks by decreasing near-road air pollution concentrations. However, while we understand the mechanisms that determine the mitigation caused by solid barriers, we still have questions about how vegetative barriers affect dispersion. The US EPA conducted several field experiments to understand the effects of vegetation barriers on dispersion of pollutants near roadways (e.g. 2008 North Carolina study and 2014 California study) that indicate the reduction of near-road pollutant concentrations can be up to 30% due to the barrier effects. The results of these field studies are being used to develop and evaluate dispersion models that account for the effects of near-road vegetative barriers. These models can be used for evaluating the effectiveness of vegetation barriers as a potential mitigation strategy to reduce exposure to traffic-related pollutants and their associated adverse health effects. This paper presents the results of the analysis of the field studies and discusses dispersion models being used to describe the data in order to simulate the effects of near-road barriers and to develop recommendations for model improvements
Keywords: roadways; barriers; vegetation; dispersion; models.
Analysis of the internal boundary layer formation on tropical coastal regions using SODAR data in Rio de Janeiro, Brazil
by Leonardo Aragão, Silvana Di Sabatino, Luiz Claudio Pimentel, Fernando Duda
Abstract: This paper investigates local circulation features in the industrialised coastal region of Santa Cruz, Rio de Janeiro, Brazil, an area characterised by poor air quality. A better understanding of local circulation is expected to have an impact on the choice of suitable dispersion models and/or development of new ones to be used to plan mitigation strategies to reduce air pollution in the area. The topographic characteristics and the variety of atmospheric phenomena acting over the area suggest the formation of Internal Boundary Layers (IBLs) during cold front and bay breeze flows, whose parameterisation is often employed in air quality modelling. Preliminary results using data from acoustic atmospheric profilers show a frequent occurrence of IBL formation during bay breeze periods, coinciding with flow direction upstream of the major industries and having an impact on the most populated area of this region. Vertical profiles of main meteorological variables are evaluated, together with surface weather stations and satellite data, to derive a detailed physics-based description of the various stages of bay breeze in terms of the main forces, duration and atmospheric stabilities. It is found that the development phase of the sea breeze coincides with the largest bay/land differences and, consequently, it is the condition in which to observe the most pronounced IBL formation.
Keywords: sea breeze; acoustic soundings; SODAR; vertical profiles; internal boundary layer; tropical meteorology.
Model chain for buoyant plume dispersion
by Andrea Bisignano, Luca Mortarini, Enrico Ferrero, Stefano Alessandrini
Abstract: A new original software interface between the WRF mesoscale meteorological
model and the SPRAYWEB dispersion model has been developed. The model chain was
designed as a highly responsive tool for risk assessment and emergency-response purposes. The model interface reads the wind and temperature fields provided by WRF and interpolates them on a fixed-in-time grid, which is the input to the dispersion model. Furthermore, it calculates the turbulence-parameter vertical profiles, based on the surface-layer data provided by WRF. In this work, we simulate the dispersion of a high buoyancy plume. The model chain performances were tested against the Bull Run dataset.
Keywords: Lagrangian model; pollution dispersion; plume rise.
New power law inflow boundary conditions for street-scale modelling
by Vasilis Akylas, Fotios Barmpas, Nicolas Moussiopoulos, George Tsegas
Abstract: In street-scale numerical simulations using computational fluid dynamics models, normally the inlet flow should preserve the horizontal homogeneity upstream and downstream of the area where the resolved obstacles reside. Hence, the vertical profiles of the main atmospheric flow quantities must comply with the roughness characteristics of the ground surface. Horizontally homogenous boundary conditions do not normally agree with field measurements while at the same time the profiles obtained by measurements do not preserve the homogeneity of the flow. As a result, in recent years alternative sets of boundary conditions have been proposed in order to bridge the gap between real life vertical profiles of the atmospheric boundary layer and those applied as input boundary conditions for modelling purposes. In the present study the homogeneity of the boundary conditions is addressed by applying the power law for the mean wind speed to obtain the appropriate vertical profiles.
Keywords: atmospheric boundary layer; computational fluid dynamics; boundary conditions; microscale; power law; street scale modelling.
Validation of meteorological forecasts in fine spatial and temporal resolution produced as an input for dispersion models
by Primož Mlakar, Dragana Kokal, Boštjan Grašič, Marija Zlata Božnar, Dejan Gradišar, Juš Kocijan
Abstract: In conditions of complex terrain, modelling of air pollutant dispersion still has a number of scientific challenges. Ideally, appropriate meteorological data should be available for modelling. Unfortunately, for many purposes, there is no time to carry out suitable measuring campaigns. Therefore, the results of prognostic weather forecasts (NWP models) are being widely used. However, these models still have quite a few disadvantages when their results are used as input for dispersion models over complex terrain. This study presents the validation of the quality of the weather forecasts in the surroundings of the Nuclear Power Plant Krko in Slovenia, an area with highly complex terrain and the resulting complex meteorological characteristics. The forecast is available for a horizontal resolution of 2 km and half hour temporal interval and seven days in advance. The predicted meteorological parameters are validated using the measured meteorological parameters.
Keywords: validation; weather forecast; fine spatial and temporal resolution; complex terrain.
A review of dispersion modelling of agricultural and bioaerosol emissions with non-point sources
by Jenny Stocker, Andrew Ellis, Steve Smith, David Carruthers, Akula Venkatram, William Dale, Mark Attree
Abstract: This paper presents a review of pollutant dispersion modelling from non-point sources, focused on agricultural and bioaerosol sources. Relevant non-point source characteristics were collated from a literature review. These values were used to describe a typical agricultural source using line, area, volume and jet source types in the plume dispersion models ADMS and AERMOD; predicted downwind pollutant concentrations are compared. The modelling shows that predicted ground-level concentrations beyond approximately 100m downwind are similar for the majority of non-point source types. ADMS and AERMOD were used to represent releases from four sheds housing intensively farmed poultry as a case study. When the emission and volume flow rates used in the modelling were derived from measurements, the models give reasonably accurate predictions. However, for releases with non-negligible efflux, modelling using non-point sources allowing for the momentum and buoyancy of the release has much better agreement with observations than those that do not.
Keywords: dispersion; ammonia; odour; non-point sources; agriculture; poultry.
Time scale analysis of chemically reactive pollutants over urban roughness in the atmospheric boundary layer
by Zhangquan Wu, Chun Ho Liu
Abstract: Most practical dispersion models assume inert pollutants but air pollutants are often chemically reactive. There is thus a need for including pollution chemistry in plume dispersion models. In this study, turbulent dispersion of reactive pollutants in the neutral atmospheric boundary layer (ABL) over a hypothetical urban area in the form of an array 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, mixes with ozone (O3) and produces nitrogen dioxide (NO2) to model bimolecular chemical reaction. The time scales of NO oxidation and dispersion are compared in detail. It is found that they are coupled with each other and collectively modify the dispersion coefficient.
Keywords: air pollutant dispersion; large-eddy simulation; pollution physics and chemistry.
Pollutant removal mechanism in two-dimensional street canyons: a laboratory study
by Annalisa Di Bernardino, Paolo Monti, Leuzzi Giovanni, Giorgio Querzoli
Abstract: Velocity and concentration fields have been measured simultaneously in the water channel to quantify the turbulent dispersion of a passive tracer emitted at street level by a line source within an idealised urban canyon. The experiment has been conducted for an arrangement of two-dimensional obstacles with an aspect ratio of unity. Statistical moments of velocity and concentration have been calculated with high spatial resolution. Furthermore, the simultaneous measure of velocity and concentration at the same point made it possible to determine the tracer flux in the whole domain as well as to quantify the removal and re-entrainment of the pollutant through the canyon top.
Keywords: street canyon; concentration flux; concentration peaks; water channel; line source; building; urban canopy; skimming flow; image analysis; PLIF.
Definition of typical-day dispersion patterns as a consequence of a hazardous release
by Stefano Alessandrini, Francois Vandenberghe, Josh Hacker
Abstract: Self-organising maps (SOMs), a particular application of artificial neural networks, are used to extract a given number of typical days from a 30-year long record of 24-hour meteorology and concentration fields. SOMs represent a mechanism for defining complex relationships in multidimensional datasets. The proposed methodology provides information regarding the probability of a typical time evolution of the concentration patterns (typical days), which could be important for some applications when estimating a priori the impact of a potential release of toxic substances. We have run the Weather and Research Forecasting (WRF) model for a defined given month over a 30-year period with two nested grids to generate the required input for the Second-order Closure Integrated Puff diffusion model (SCIPUFF). The dispersion simulations are related to an instant point release at ground level and are carried out during the same period and in the spatial domain covered by the inner WRF grid. An array for each day, including the wind components, boundary layer height, and integrated concentration over 24 hours at all the grid points, is input to the SOM to perform an iterative learning process. The result is a number of typical days associated with different probabilities of occurrence. An assessment of the performance and reliability of this approach will be presented.
Keywords: self-organising maps; transport and dispersion models; neural network; air quality; risk assessment; Scipuff.
Community multi-scale air quality atmospheric dispersion model adaptation for Hungary
by Dóra Lázár, Tamás Weidinger
Abstract: In recent years it has become increasingly important to measure and predict the concentration of harmful atmospheric pollutants such as dust, aerosol particles, nitrogen compounds, and ozone. By adapting the community multi-scale air quality (CMAQ) model we have implemented a coupled air qualitymeteorological environmental model system, primarily for the representation of atmospheric ozone in Hungary. We used the WRF model in order to generate the meteorological driver database and the so-called SMOKE model for the construction of the input emission database. Our model system is separately run on three levels of a one-way nested grid with spacings of 108/36/12 km. We studied ozone forecasts based on different model settings and transition times, using several verification methods. This paper presents the outline of the project work, and the first results of concentration calculations are compared with national ambient air station data. Our results show that the night-time concentration of ozone is overestimated in our adapted model system.
Keywords: air-quality modelling; ozone; CMAQ; SMOKE; WRF; emission; model adaptation.
The air quality in narrow two-dimensional urban canyons with pitched and flat roof buildings
by Simone Ferrari, Maria Grazia Badas, Michela Garau, Giorgio Querzoli, Alessandro Seoni
Abstract: This paper deals with the air quality in narrow urban canyons. The first target is the investigation of the modifications that the roof shape induces in the flow and turbulence, through the comparison of velocity fields, turbulence characteristics and air exchanges with the outer flow in arrays of buildings with flat and pitched roofs. The second target is the assessment of the capability of a RANS model to correctly simulate the flow. The analysed quantities include velocity fields and profiles, turbulence characteristics fields and an integral parameter, the vertical air-exchange rate ACH, measuring the rate of air removal from a street canyon. Results show that the pitched roof strongly modifies the topology of the flow and increases the turbulence and the air exchange between the canyon and the external flow, so the choice of the roof shape can be meaningful for building design, planning strategies and regulatory purposes.
Keywords: narrow urban canyon; air quality; natural ventilation; pitched roof; RANS simulation; laboratory simulation.
Validation of Gaussian plume model AEROPOL against Cabauw field experiment
by Marko Kaasik, Gertie Geertsema, Rinus Scheele
Abstract: The Gaussian dispersion model AEROPOL is validated against the Cabauw (1977-1978) dataset, by applying the parameters and rules from the model validation kit. The purpose to revisit this experiment is preparation for fast response to buoyant accidental releases. In the AEROPOL model the classical Pasquill-Gifford stability and a scheme based on Lagrangian time scales are used as alternatives. Validation is based on correlation, fractional bias, fractional sigma, NMSE and fraction in factor 2, applying these statistics to maximal arc-wise, near-centreline and cross-wind integrated concentrations. Both parameterisations are found fairly adequate. The Gryning scheme results in too wide a Gaussian spread and thus in lower maxima compared to measurements, whereas the Pasquill parameterisation gives sharper maxima, which makes the statistics more sensitive to small discrepancies in plume position. The average wind between the lowest measurement level and release level is found to be a good approximation to represent the position of the Gaussian plume.
Keywords: Gaussian plume; dispersion experiment; Cabauw; AEROPOL; HARMONIE; model validation kit.
The use of a new diagram for the analysis of the daily cycles in the air-pollution data
by Marija Zlata Božnar, Boštjan Grašič, Primož Mlakar, Dejan Gradišar, Juš Kocijan
Abstract: From a temporal viewpoint, air pollution has significant daily patterns/cycles of behaviour. These cycles are conditioned by anthropogenic and natural phenomena. In both cases, a detailed observation and an understanding of the daily cycles rules or daily patterns of air pollution can be significant and at the same time can contribute to more effective measures to reduce the harmful impact of air pollution on human health. In this paper, the new sunflower diagram is presented. The key advantage of the sunflower diagram is the ease of understanding the result and the ability to present information in the form of a graphic pattern, allowing the user to quickly understand the content. Using the sunflower diagram, we will present an analysis of the meteorological parameters that are important for understanding air pollution and air-pollution data for different locations in Slovenia.
Keywords: daily cycles; analysis tool; sunflower diagram; air-pollution flower; weather flower; wind flower.
Effect of the long-range transport on the air quality of the Greater Budapest area
by Zita Ferenczi, Laszlo Bozo
Abstract: SO2, NO2 and Particulate Matter (PM) are air pollutants, generated by a variety of human activities and can travel long distances in the atmosphere and cause a wide range of air quality problems in Europe. For some cities the influence of transboundary and national contributions in PM concentrations are dominant, and only a little improvement can be expected from local control policies. The air quality of Budapest is determined mainly by the local residential heating and traffic emissions combined with the meteorological conditions. Sometimes the impact of the transboundary sources can be negligible, especially under special meteorological conditions when the local effects determine the air quality of Budapest, but sometimes it could be responsible for the formation of air pollution episodes. In this research the effect of long-range transport on the air quality of Budapest was analysed in detail, using the outputs of EMEP chemical transport model.
Keywords: long-range transport; EMEP chemical transport model; urban air quality; emission.
Special Issue on: HARMO17
Application of inverse dispersion modelling for the determination of PM emission factors from fugitive dust sources in open-pit lignite mines
by Athanasios Triantafyllou, Nicolas Moussiopoulos, Athina Krestou, George Tsegas, Fotios Barmpas, Stelios Garas, Μelina Andreadou
Abstract: The operation of large open-pit lignite mines represents a significant source of fugitive dust emissions connected to energy production. Emission inventories can be used to provide operational estimates of the total dust burden in the surrounding areas attributable to mining operations. In this work, a methodology based on the inverse dispersion modelling approach, combining two different dispersion models, is used for preparing a dust emissions inventory for several activity types in the lignite mines of Western Macedonia, Greece. A 3-year campaign of field measurement experiments provides the necessary meteorological data and upwind-downwind concentration levels in the area of each activity. A comparison of calculated emission rates provided by the two dispersion models indicates a very good agreement, while the normalised downwind concentration timeseries are accurately reproduced. Emission factors are calculated for each experiment and per-activity, leading to the formulation of empirical relations for the total fugitive dust emissions.
Keywords: inverse dispersion modelling; fugitive dust sources; emission factors; open pit mines.