International Journal of Environment and Pollution (38 papers in press)
The leaching behaviour of Cu, Zn and Pb from waste printed circuit boards by [BSO4HPy]HSO4
by Mengjun Chen, Sha Zhang, Jiqin Wang, Bin Wang, Jinxiu Huang, Shu Chen
Abstract: Currently, researches are mainly focused on how to recycle valuable metals from waste printed circuit boards (WPCBs), but rarely against the toxic substances, such as zinc and lead, during the recycling process. In this research, the effect of zinc and lead during the process of leaching copper from WPCBs by an acidic ionic liquid, N-sulfobutylpyridinium hydrosulfate ([BSO4HPy]HSO4), was investigated in detail. Results showed that copper and zinc could be successfully leached out by [BSO4HPy]HSO4. When 1 g of 0.1-0.25 mm WPCBs powder was leached by 25 mL 80% (v/v) ionic liquid and 10 mL 30% hydrogen peroxide at 40 oC for 2 h, copper and zinc leaching rate could be up to 99.75% and 93.02%, respectively. The added amount of H2O2, the solid-liquid ratio and the temperature significantly impact the leaching rate of copper and zinc. On the contrary, the lead leaching rate is hardly influenced by these factors, maintaining at around 2%. Thus, during the leaching process, zinc could significantly influence the leaching of copper, which is totally different for lead. Leaching kinetics analysis indicated that the leaching of copper and zinc is controlled by solid film diffusion, and the leaching of lead is controlled by chemical reaction.
Keywords: WPCBs; ionic liquid; copper; N-sulfobutylpyridinium hydrosulfate.
A meteorological discourse on extreme storm events driven by Asian slum emissions
by Sat Ghosh, Alan Gadian, Steve Dobbie, Arkayan Samaddar, Anuj Sharma, Pranav Chandramouli, Aditi Palsapure
Abstract: Increasingly the world over, climate modellers have suggested that local emissions may well affect cyclonic storms. The eastern coast of India, home to mega cities, is routinely battered by such storms over the period from October to December. Additionally, these cities house millions of slum dwellers who cook their meals from unseasoned firewood, yielding substantial amounts of biomass particles. These particles chemically age within a polluted air mass, rendering them active as cloud condensation nuclei (CCN). This first study shows the genesis, progression and evolution of one such tropical disturbance, Hurricane Thane, which was modulated by these transient emissions, devastating the coast of Tamil Nadu on 30 December 2011. We show that auto-conversion rates converting cloud water to rain water are significantly altered by up to 12% when such emissions are included. Carefully designed numerical experiments using the Weather Research and Forecasting (WRF) model show an increase of 20.5% in the cloud water amounts, when these effects are included. Emissions from Asian slums may well alter cyclonic activity elsewhere in South Asia. This study, using a state of the art numerical weather prediction model, indicates how local effects can be quickly obtained through offline modelling. In a nation of continental proportion where millions of underprivileged persons live close to the most vulnerable coastal locations, quick alerting mechanisms by local institutions with limited resources (Government Colleges and Engineering Institutes) may well form a support system linking ordinary citizens with the local coastguard for purposes of mass evacuation well in advance.
Keywords: aerosols and particles; cloud physics and chemistry; pollution; urban and regional; precipitation.
The strategy for protecting threatened forest species richness in northeastern China from the effects of climate change
by Ji-Zhong Wan, Chun-Jing Wang, Shi-Jie Han, Li-Hua Wang, Jing-Hua Yu
Abstract: Climate change has the potential to severely threaten the plant species in the forests of northeastern China. The field surveys performed for this study spanned four years and identified the endangered species present in the forests of northeastern China. We conducted a detailed investigation of 2884 study plots and selected 29 nationally protected plant species (sample sizes ≥ 5), namely, threatened species for further analysis. We modelled and mapped the potential distributions of these 29 threatened species, and found that the species richness hotspots are currently distributed in the eastern and northeastern areas of the studied region and will move geographically. This study focused on the strategy for protecting threatened forest species richness by analysing the change trend of species richness and planning of PPAs due to climate change.
Keywords: species richness; climate change; Maxent; zonation; nature reserve; forest plants.
Biological denitrification and dephosphorization of a fixed bed reactor packed with long-term carbon release composite under magnetic field
by Shuchen Tu, Fengzhu Lv, Zilin Meng, Rui Zhang, Yihe Zhang
Abstract: A novel multiple-component carbon source mainly with hemp fibre (HF) and biodegradable polybutylene succinate (PBS) was prepared and filled into two fixed bed bioreactors to remove nitrate nitrogen and phosphorus from simulated groundwater. A 121 days monitoring indicates the denitrification and dephosphorisation of bacteria are influenced by temperature. But a magnetic field can decrease the influence. As the operation temperature was 30-36 oC, the average nitrate nitrogen and total phosphorus (TP) removal degree in reactor 1 (without electromagnetic field) was 91.05% and 71.34%, while nitrite remained at low levels (less than 0.2 mg/L). As a magnetic field was introduced, the average nitrogen and phosphorus removals were improved to 93.18% and 78.68%, respectively. Meanwhile, the average effluent concentration of chemical oxygen demand (COD), decreased from 51.2 mgL-1 to 30.8 mgL-1. The morphology and the biofilm attaching amount measurement indicated more bacteria were attached onto the composite and more composite was consumed correspondingly but inhomogeneously. These data show that a magnetic field could improve the growth of bacteria and their attachment onto the composites. The prepared composite is a long-term carbon-release material and the fabricated fixed bed reactors are high performance reactors for NO3-N removal.
Keywords: denitrification; biofilm; magnetic field; carbon sources; water treatment.
Identification of dust transport patterns and sources by using MODIS: a technique developed to discriminate dust and clouds
by Zaibun Nisa, Salman Atif, Faheem Khokhar
Abstract: This study focuses on exploring the meteorological factors behind dust emergence and spread over Baluchistan in the post-monsoon season, as much of the existing research has been done on spring episodes. With the integration of remote sensing and meteorological methods, efforts were made to explore the relationship of dust storms with land-atmospheric conditions, such as surface temperature and aerosol optical depth (AOD) in the selected season. To map dust spatial distribution, a cloud-free product of Brightness Temperature Difference (BTD) composite from MODIS terra level 1B emissive bands were prepared and classified using the maximum likelihood technique. Two case studies of October 2004 and December 2011 exhibited the short-term cooling effect on the surface due to increased AOD. Dominant synoptic patterns of cold trough front formation with low-pressure centre development over eastern Iran were found as a significant feature of dust mobility towards warmer Baluchistan. Back trajectory analysis revealed that dust from south western Kazakhstan and eastern Europe converged over land of Kyrgyzstan and Tajikistan, which may have instigated its uplift over Helmand Basin. Evidence of a dominant effect of air masses from Middle East, Iran and Iraq was found in post-monsoon dust episodes.
Keywords: dust transport; dust-enhanced composite; aerosol thickness; back trajectories; dust storm meteorology; Pakistan.
A Lagrangian dispersion model with a stochastic equation for the temperature fluctuations
by Andrea Bisignano, Enrico Ferrero, Stefano Alessandrini
Abstract: A new plume rise scheme for the Lagrangian stochastic model SPRAYWEB is developed and tested. The plume rise scheme is based on a stochastic differential equation for the potential temperature fluctuations coupled with the equations for the wind velocity fluctuation components. The new approach is tested against measured data from a water tank experiment (Weil et al., 2002). The results are discussed in term of statistical indices and scatter plots. For the sake of comparison, the new scheme performance is compared with the algorithm used in SPRAYWEB formerly proposed by Anfossi et al. (1993) which doesnt account for the temperature fluctuations. The results obtained with the novel plume rise scheme are generally satisfactory. A better agreement is found for the vertical standard deviation with respect to the results given by the Anfossi et al. (1993) scheme.
Keywords: plume rise; Lagrangian stochastic dispersion model; buoyancy; temperature fluctuations.
A theoretical study on the mechanism and kinetic of toxic PCDDs destruction by OH radical
by Zhengcheng Wen, Shengji Li, Heping Li, Yuan Li
Abstract: The mechanism and kinetics of toxic PCDDs destruction by OH radicals is investigated in detail, employing quantum chemistry in this paper. Theoretical results show that OH radicals degrade toxic PCDDs via substituting chlorine at the 2,3,7,and 8 positions. The kinetic parameters of the reactions are also calculated by transition state theory. By comparison, the rate constant of OCDD destruction by OH is found to be in agreement with the experimental result, especially at 298 K. This indicates that the quantum chemistry study in this paper is reliable. The rate constant of 2,3,7,8-TCDD destruction is obviously lower than that of other toxic PCDDs. The reason is analysed and discussed by using NBO charge analysis. Owing to the effect of Cl atoms at 1,4,6,and 9 positions, Cl atoms at 2,3,7,and 8 positions have more positive charge. At aromatic rings, the more positive charge chlorine has, the easier chlorine is to be substituted. The quantum chemistry study can be believed to supply an important theoretical basis for the further investigation on the removal of toxic PCDDs by using the catalytic oxidation technology.
Keywords: PCDDs; OH radical; quantum chemistry; destruction mechanism; kinetic parameters.
Complex analysis of heavy metals mobility in the soils of the border town of Blagoveshchensk (Far East, Russia)
by Valentina Radomskaya, Nina Borodina, Lyudmila Pavlova
Abstract: A comprehensive assessment of the degree of heavy metals mobility in the soils of Blagoveshchensk was carried out, based on research on heavy metals fractional composition and mathematical statistics of the analysis of the data obtained. It was shown that the majority of Cu, Cr, Ni, Co and Pb accumulates in residual fraction components and that Mn, Cd and Zn accumulate in Fe- and Mn-hydroxides and the residual fraction. Under the increased technogenic addition of Zn contaminants, Pb was fixed in soil due to unstable specific absorption, Cd due to specific absorption and in hydroxide fraction. Cu was bound to an organic fraction, and Cr, Co and Ni to organic and hydroxide fractions. In urban soils compared with background soil, there was increased potential for the mobility of Zn, Pb, Ni, Cu, Cr and Cd. Among the elements studied, Zn, Mn and Cd, whose potential mobility corresponds to a high level of danger, posed the greatest danger. For Pb, Ni and Co, there is moderate risk of inclusion in the food chain.
Keywords: heavy metals; mobility; fractional composition; urban soils.
Urban emission inventory optimisation using sensor data, an urban air quality model and inversion techniques
by David Carruthers, Amy Stidworthy, Dan Clarke, Jo Dicks, Rod Jones, Ian Leslie, Olalekan Popoola, Martin Seaton
Abstract: An optimisation scheme has been developed that applies a Bayesian inversion technique to a high resolution (street-level) atmospheric dispersion model to modify pollution emission rates based on sensor data. The scheme minimises a cost function using a non-negative least squares solver. For the required covariance matrices assumptions are made regarding the magnitude of the uncertainties in source emissions and measurements and the correlation in uncertainties between different source emissions and different measurement sites. The scheme has been tested in an initial case study in Cambridge, UK, using monitored data from four reference monitors and twenty AQMesh sensor pods for the period, 30 June 2016 30 September 2016. Hourly NOx concentrations from road sources modelled using ADMS-Urban and observed concentrations were processed using the optimisation scheme and the adjusted emissions were re-modelled. The optimisation scheme reduced average road emissions on average by 6.5% compared to the original estimates, changed the diurnal profile of emissions and improved model accuracy at four reference sites.
Keywords: inversion; optimisation; emissions; ADMS-Urban; sensors.
Independent analysis of time-varying hydrogen cyanide gas exposures on rats using toxic load-based modelling
by Alexander Slawik, James Silva, Kevin Axelrod, Jeffry Urban, Nathan Platt
Abstract: The US Defence Threat Reduction Agency (DTRA) sponsored a two-year set of experiments, conducted in 2012 and 2013, that were designed and executed by the US Armys Edgewood Chemical and Biological Center (ECBC) and the Naval Medical Research Unit Dayton (NAMRU-D) to explore time-varying inhalation exposures of hydrogen cyanide gas on rats. Our analysis, detailed in a separate paper, finds that a single set of fitted parameters for the toxic load model (i.e., the toxic load exponent n, probit slope m, and median lethal exposure TL50) cannot accurately model the single exposure experimental data across the experiments full range of time from 2.3 to 30 minutes but can on the longer timescales of 10 to 30 minutes. However, none of the toxic load models that we considered fit the experimental data for the novel, time-varying exposures well, with the Average Concentration and Griffiths-Megson models providing the least inaccurate casualty predictions.
Keywords: casualty assessment; consequence assessment; Haber’s law; toxic load modelling.
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.
An approach for selection of solid waste disposal site by rapid impact assessment matrix and environmental performance index analysis
by Nekram Rawal
Abstract: The selection of a suitable landfill site for disposal of municipal solid waste is an important challenge for the engineered system. The physical, biological, sociological and economic aspects should be examined with the aim to measure the overall impact of the waste disposal issues before the selection of an appropriate landfill site. In this study, the selection procedure of appropriate landfill site among four landfill sites, i.e Kareli, Alopibagh, Phaphamau and Ganja landfill sites for disposal of waste in Allahabad (India) is highlighted. A questionnaire comprising physical/chemical, biological/ecological, social/cultural and economic/operational aspects was prepared. A survey was conducted among the residents and local public residing near all four landfill sites. The responses were analysed with the Rapid Impact Assessment Matrix (RIAM) tool to quantify the intangible effects in terms of environmental score. The results were used to compare the cumulative impacts in a rational manner. Environmental Performance Index (EPI) was computed for all four sites to intelligibly ascertain the efficacy of the systems/methodologies involved in the solid waste disposal facility. The results revealed that Ganja landfill site was the best site compared with the Kareli, Alopibagh and Phaphamau landfill sites. The EPI of four sites, viz., Kareli, Alopibagh, Phaphamau and Ganja, were -110.315, -123.541, 98.867 and -54.586, respectively. The EPI of all the four sites had negative values indicating that these are not appropriate for landfilling or dumping.
Keywords: municipal solid waste; waste disposal; rapid impact assessment matrix; environmental score; environmental performance index.
Advanced algorithms for studying the impact of climate changes on ozone levels in the atmosphere
by Istvan Farago, Zahari Zlatev, Ivan Dimov, Agnes Havasi, Krassimir Georgiev
Abstract: The problem caused by the rapid climate changes is very challenging for modern society. The steady increase of the global temperature, especially in the Arctic areas, has different consequences. Most of them are at least potentially dangerous. Some aspects of the impact of the increased temperature on some pollution levels, which could be harmful for some groups of human beings (primarily for people suffering from asthmatic diseases) has been studied by developing climate scenarios and by running them over a period of 16 consecutive years. The mathematical model used in the experiments is a system of nonlinear partial differential equations (PDEs) and the space domain contains the whole of Europe together with some of its surroundings. Difficult computational problems will arise after the direct discretisation of the spatial derivatives, because this results in huge systems of linear algebraic equations, containing often hundreds of millions of equations, which have to be handled numerically during many time-steps for each of the selected scenarios and for each of the chosen years. The enormous computational problems can be treated successfully only by resolving simultaneously five important tasks. More precisely, it is necessary (a) to apply accurate and efficient numerical algorithms, (b) to select an appropriate splitting procedure, (c) to develop parallel codes, (d) to use high-speed computers in the runs, and (e) to exploit as well as possible the cache memories of the available parallel computer. Selected numerical results will be presented in this paper in order to illustrate both the fact that the developed code is efficient and the fact that the future climate changes will result in consistent increase of some pollution levels.
Keywords: large-scale environmental models; systems of non-linear PDEs; numerical algorithms; splitting techniques; parallel codes; high-speed computers; climate changes; ozone levels; damaging effects.
Applying WRF-CMAQ models for assessment of sulphur and nitrogen deposition in Bulgaria for the years 2016 and 2017
by Dimiter Syrakov, Maria Prodanova, Emilia Georgieva, Elena Hristova
Abstract: Wet, dry and total depositions of sulphur (S) and nitrogen (N) in Bulgaria are simulated on an annual and seasonal basis for the years 2016 and 2017 using WRF-CMAQ (9 km grid resolution). The mean annual values for wet depositions are about 1300 kg km-2, the dry depositions are slightly lower for S and significantly lower for N (180 kg km-2). The highest modelled wet depositions are in the western and south-western part of the country, and the highest dry depositions are in the northern and eastern parts. The comparison for the wet depositions at three sites with precipitation chemistry data indicates overestimation. A precipitation bias adjustment applied to the modelled depositions results in decrease of the normalised mean bias by a factor of 3. Comparison with modelled deposition data from literature for this region of the country is also provided.
Keywords: depositions; WRF-CMAQ; precipitation chemistry; Bulgaria; comparison; bias adjustment.
Analysis of regional climate model simulations for Central Europe as a potential tool to assess weather-related air quality conditions
by Ildiko Pieczka, Rita Pongracz, Csilla Peline Nemeth, Timea Kalmar
Abstract: Potentially adverse air quality is discussed in the present paper via its relation with wind conditions and boundary layer thickness. The main goal of the study is to evaluate different RegCM simulations (using two different model versions) for the 1981-1990 period, driven by either reanalysis data or global climate models output. For the validation purpose, wind speed, temperature, planetary boundary layer (PBL) height, and a derived index, the so-called Holst stagnation index are analysed and compared with the reference data. According to the results, wind is overestimated throughout the year, temperature is overestimated in the plain areas, whereas it is underestimated in the mountains. The height of the PBL is generally overestimated, and substantial differences are identified between RegCM4.5 and RegCM4.3 simulations. Consequently, these result in the substantial underestimations of the Holst stagnation index, and the frequency of potential adverse air quality, although the annual cycles are reproduced well. In order to prepare reliable projections, newer RegCM model versions and/or different model setups must be further tested as to whether they are able to reproduce past meteorological conditions related to air quality. We found potential in using a different PBL parameterisation scheme instead of the previously widely used Holtslag scheme.
Keywords: planetary boundary layer; wind; Holst stagnation index; RegCM; regional climate model; validation; air pollution; Carpathian Basin; Central Europe.
Current trends in nanotechnology for bioremediation
by Stephen Rathinaraj Benjamin, Fabio De Lima, Eridan Orlando Pereira Tramontina Florean, Maria Izabel Florindo Guedes
Abstract: Nanotechnology is an emerging field to produce nano-scale products with more efficient reactivity and larger surface area than the bulk phase. These unique attributes of nanoparticles offer immense potential for their application to clean up sites contaminated with petroleum hydrocarbons, pesticides, and metals. Compared with the conventional physicochemical methods of remediation of contaminated sites, bioremediation has been drawing increasing attention owing to its economic, eco-friendly and self-propelling attributes. Nanoparticles (NPs) can be applied directly for removal of organic contaminants through adsorption or chemical modification. They can also serve as a facilitator in microbial remediation of contaminants either by immobilising or through the induced production of remediating microbial enzymes. The present review provides an overview of different types of nanotechnology with biological and plant-based bioremediation approaches.
Keywords: bioremediation; nanotechnology; genetic engineering; recombinant DNA technology.
Assessment of fluoride hazard in groundwater of Palghat District, Kerala: a GIS approach
by Thangavelu Arumugam, R. Prabitha, K. Sapna
Abstract: Groundwater is a dynamic and replenishable natural resource all over the Earth's surface. Groundwater moves downward due to the pull of gravity and it can also move up because it will flow from higher pressure areas to lower pressure areas. The rate of groundwater flow is controlled by two properties of the rocks present: the porosity and the permeability. Generally, the groundwater quality depends on the quality of recharged water, atmospheric precipitation, inland surface water and subsurface geochemical processes. Fluoride contamination of groundwater is a growing problem in many parts of the world. The major sources of fluoride in groundwater are fluoride-bearing minerals, such as fluorspar, cryolite, fluorapatite and hydroxylapatite, in rocks. The problem of high fluoride concentration in groundwater resources has now become one of the most important toxicological and geo-environmental issues in India.
Keywords: groundwater; fluoride; GIS; IDW; statistical analysis.
Global climate-driven effects on urban air pollution simulations using very high spatial resolution
by Roberto San Jose, Juan L. Perez, Libia Perez, Rosa M. Gonzalez
Abstract: The city's response to future climate scenarios is an important issue to which this study contributes an attempt to improve the understanding of the relationships between climate and air quality in urban areas. A dynamic downscaling tool has been implemented that uses global climate data with 1
Keywords: dynamical downscaling; CFD; climate scenario; air pollution.
Special Issue on: HARMO 18 Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes
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 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.
A solution of the time-dependent advection-diffusion equation
by Tiziano Tirabassi, Everson Gomes, Daniela Buske, Marco Vilhena
Abstract: We present an analytical solution that considers time dependence in the wind profile and the eddy diffusivity. The solution accepts any profiles of wind and eddy coefficient diffusions in a limited planetary boundary layer. The solution is based on the idea of a decomposition method upon expanding the pollutant concentration in a truncated series. This produces a set of recursive equations whose solutions are known. Each equation of this set is solved by the GILTT (Generalized Integral Laplace Transform Technique) method. The solution's ability to represent real situations was checked by comparing model predictions with the OLAD (Over-Land Along-wind Dispersion) experimental dataset.
Keywords: air pollution modelling; advection-diffusion equation; analytical solution; decomposition; planetary boundary layer; environmental management; validation by experimental data; air pollution; atmospheric environment.
Spatial representativeness evaluation of air quality monitoring sites by point-centred variography
by Oliver Kracht, Michel Gerboles
Abstract: We propose a geostatistical technique based on point-centred semi-variograms that can be used to derive valuable information about the spatial representativeness of air quality monitoring sites. Whereas classical geostatistics describes the spatial correlation structure of a concentration field in terms of the variogram, point-centred variography is based on the average of squared concentration differences observed in pairs formed from a particular central point and the set of all other points in the domain. It thereby places a monitoring station in the context of the local or regional air quality pattern. We demonstrate how a mathematical inversion of the point-centred variogram can provide estimates of the extent of the representativeness area of a monitoring site. The application of this approach is tested on a set of modelling data from the city of Antwerp (14-day averages of PM10, NO2 and ozone for 341 virtual receptor points), which was used for the FAIRMODE/AQUILA intercomparison exercise of methods for the assessment of spatial representativeness. In this evaluation of three selected monitoring sites in an urban area type setting of Antwerp, the extent of spatial representativeness was shown to be strongly dependent on the pollutant and on the type of station. Numerical estimates ranged between the largest extent of 10,864 m obtained for PM10 for an urban background site, and zero for NO2 for an urban traffic site.
Keywords: point-centred variography; spatial representativeness; geostatistics; air pollution; air quality monitoring; measurements; modelling.
Modelling the Air quality for assessing the health benefits of urban regeneration: the case of Tallinn city centre, Estonia
by Marko Kaasik, Mihkel Pindus, Tanel Tamm, Hans Orru
Abstract: Concentrations of nitrogen dioxide and particulate matter were modelled to assess the health benefits of an urban regeneration scenario for the central part of Tallinn, where the traffic on two of the main streets will be reduced to create a more friendly space for active commuters. To model the air quality the stationary Gaussian plume model AEROPOL was used with a 25 m grid resolution. The model was validated against a stationary air quality monitoring station in the domain. The health benefits of the scenarios were calculated based on the changes in air pollution exposures for residents and daily visitors, using methods of health impact assessment. This research predicts that each year the reduction of exhaust (indicated by NO2) and road dust (indicated by PM10) exposure in the city centre would prevent up to 0.29 premature deaths (-27%) among the general population, 0.57 deaths (-3.6%) among daily visitors, 0.18 deaths (-21.2%) among pedestrians, and 0.03 deaths (-24.7%) among people public transport users.
Keywords: nitrogen dioxide; PM10; particulate matter; Gaussian dispersion model; urban; health impact assessment; mortality; premature death.
Application of degree-day factors for residential emission estimates and air quality forecasting
by Maciej Kryza, Małgorzata Werner, Anthony Dore
Abstract: Results of air quality modelling are strongly influenced by the emission inventory that is used for modelling. This is related both to spatial and temporal allocation of emission. In Poland, the share of residential combustion in total emission of PM2.5 and PM10 is very large, and the temporal profile of emission from this sector is strongly influenced by meteorological conditions (mainly air temperature). In this work, we show the performance of the WRF-Chem model forecasts, running for the area of Poland with two different approaches to temporal distribution of emission from residential combustion. For the first run, emissions are distributed temporally using the monthly, daily and hourly emission factors provided by the GENEMIS project (base run). For the second run, the model uses the heating degree-day (HDD) factors approach for SNAP sector 2 (residential combustion). The forecasts cover the period 11.02.2017-25.02.2017, during which poor air quality was observed at the beginning of the period, followed by unusually warm days with lower concentrations of pollutants. We show that both approaches result in similar model performance for both PM10 and PM2.5. However, the HDD approach leads to better forecasts for the warm days, whereas the base run forecasts often show too high concentrations of atmospheric pollutants for such periods. The mean bias is reduced for the warm period from 2.89 and 2.45 (PM10 and PM2.5 respectively) for the baserun to -2.03 and -1.18 for the HDD run. Correlation coefficients increase from 0.48 to 0.51 for PM10 and from 0.59 to 0.62 for PM2.5.
Keywords: air quality forecasts; particulate matter; residential combustion; Poland.
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