An Evaluation of Daumod Model in Estimating Urban Background Concentrations

This article presents an evaluation of the performance of the urban atmospheric dispersion model (DAUMOD) in estimating nitrogen oxides (NO_x) background concentrations in Copenhagen. Estimations of hourly average (averaged over a year), mean daily and mean monthly concentrations of NO_x are compared with observed values for two years of data. The model slightly underestimates low hourly average values and overestimates high values. The cumulative frequency distribution of mean daily concentration obtained from model estimations is in good agreement with the obtained from observed data. We performed a statistical analysis to determine the agreement between estimated and observed concentration values. The results show that 95.8% of hourly average estimations, 86.8% of mean daily and 100% of monthly average concentrations are within a factor of two of the observed values. The normalised mean square error of predictions is +0.13 for hourly average estimations, +0.22 for mean daily values and +0.02 for monthly mean concentrations. The fractional bias values are: –0.049 for hourly mean estimations, –0.047 for mean daily values and –0.053 for monthly average estimations. The values of the statistical parameters allow us to consider that though estimations are lightly larger than the observed values, the model performance is acceptable.     

Air Quality Management in Izmir Region of Turkey as Required by Clean Air Plans

As a first step to work out an abatement plan against air pollution, a local emission inventory with 1 hr temporal and 1 km spatial resolution in the city of Izmir and its surroundings was prepared. The study area consisted of a 200 × 170 km² rectangle having the city of Izmir at the centre. The studied pollutants were total particulate matter (PM), sulfur oxides (SO_x), nitrogen oxides (NO_x), volatile organic compounds (VOC) and carbon monoxide (CO). Emissions of these pollutants were determined by estimation methods making use of suitable emission factors. Emission sources were evaluated in three categories; point, area and line sources. For year 2000 total emissions in the study area on an average day were estimated as 173 tons PM, 299 tons SOx, 136 tons NOx, 68 tons VOC and 320 tons CO. At the second part of the study, calculated emissions were transformed into air quality predictions in the area by using the Industrial Source Complex – Short Term (ISCST3) dispersion model. Model results were tested with monitoring data from urban air quality stations obtained during the year 2000. Results of the past, present and future air quality estimates in the region were discussed. In order to do so, future scenarios including various control technology applications were formulated and tested to see their effect on the future air quality.     

Measuring Eddy Covariance Fluxes of Ammonia Using Tunable Diode Laser Absorption Spectroscopy

Field measurements of NH3 fluxes using an eddy covariance technique were made for a total of 60 days between July and September 2002 at an intensively managed grassland in Southern Scotland. The collected data demonstrate the suitability of a tuneable diode laser absorption spectroscopy (TDLAS) system coupled with a sonic anemometer for eddy covariance measurements. The novelty of these measurements is the application to ammonia, which has only become measurable using TDLAS techniques recently, because of its small ambient concentration. Data presented in this paper show typical features of the fluxes and concentration for the summer season. NH3 concentration and flux values are in a similar range to previous studies using flux gradient methods at the same field site, although the particularly wet season reduced the concentration of NH₃ in the air. For an example day, measured NH₃ fluxes ranged between –11 and 44 ng m^–2 s^–1 with an average value of 3.78 ng m^–2 s^–1 indicating a small net emission from the vegetation. Spectral analysis executed on the data shows the percentage of flux carried by the small eddies (from 0.2 to 2 m) suggesting that high detection frequency instruments are particularly suitable for estimating NH₃ fluxes between atmosphere and vegetation.     

Early Effects of Atmospheric Ammonia Deposition on Calluna Vulgaris (L.) Hull Growing on an Ombrotrophic Peat Bog

This paper reports data from a field study investigating the impacts of elevated ammonia (NH₃) deposition on Calluna vulgaris growing on an ombrotrophic peat bog in S.E. Scotland. Shoot extension, foliar N concentrations, chlorophyll concentration and chlorophyll fluorescence were measured during the second growing season of exposure to a gradient of ammonia concentrations. Results indicate that NH₃ increases growth between 150–200 kg N ha^–1y^–1 cumulative deposition. Foliar N content increased significantly in response to NH₃ cumulative deposition up to 400 kg N ha^–1 y^–1 whereas chlorophyll a content significantly decreased. Measurements of Fv/Fm suggest that although NH₃ exposure altered the growth and reduced chlorophyll a, the efficiency of photosystem II was insensitive to NH₃-N deposition at this stage.     

Air Pollution Zones and Harmful Pollution Levels of Alkaline Dust for Plants

For characterisation of landscapes in north-eastern Estoniaaffected by alkaline oil shale fly ash and cement dust the zonation-method based on average annual (C _y) and short-termconcentrations of pollutants in the air was used, as well as on deposition loads of dust and Ca²⁺. In the overground layer of atmosphere the zones with different air pollution loads were distinguished. A comparative analysis of pollution zones characteristics and biomonitoring data revealed that for sensitive lichen the dangerous level of alkaline dust in the air, introducingthe degradation of Sphagnum sp. at the level of C _y of dust 10–20 g m^-3 and at 0.5–1 hr maximums 100–150 g m^-3. For Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) this limited concentration (decline of growth parameters) of cement dust is correspondingly following: 30–50 g m^-3 and 150–500 g m^-3, in case of fly ash the limit level of C _y amounting 100 g m^-3. Daily deposition load of Ca²⁺ should not exceed approximately 4.5–15 mg m^-2 for lichen; for conifers the harmful pollution load is higher – >22 mg m^-2.     

Effects of Duststorms on the Air Pollution in Beijing

The objective of this study was to investigate the air pollutionin Beijing before, during, and after duststorms occur. There aretwo different phenomena of air pollution in Beijing during a duststorm; one being related to the concentration of particulatematter and the second related to gaseous chemical pollutant concentrations. In this study, the concentrations of the chemicalpollutants, such as SO₂, NO_x and CO, were high prior to the occurrence of the duststorms. At the beginning of the two duststorms studied, the air quality related to these chemicalconstituents was improved due to a strong wind blowing away the chemical pollutants, which caused a decrease in the concentrations of SO₂, CO and NO_x. During the duststorm, the concentration of particulate matter, quantified by PM₁₀, wasobserved to increase and the atmospheric visibility decreased.     

Climatology and Trends of the Temporal and Spatial Distribution of Sandstorms in Inner Mongolia

The temporal and spatial distribution of sandstorms have been investigated statistically for a period of 40 years (1961–2000),using data from 118 observatories in Inner Mongolia, P.R. of China. In terms of climate variations, the effects of changes in climate(affecting parameters such as precipitation, temperature, ENSO activities, etc.), ecological systems and human behavior on the space-time distribution of sandstorms have been studied. It is shown that in Inner Mongolia nearly all sandstorms occurred inthe central-western region during 1961–2000. Their frequency decreased from the 1960s to the 1990s. The mean annual variationshows that spring is the main sandstorm season, especially April. In view of connection with climate variations, dry and cold periods correspond with a high frequency of sandstorms,wet and warm periods with a low frequency. With respect to thespatial distribution, sandstorms hit preferably dry and warm regions. There are some relations between ENSO activities andthe sandstorm frequency. The sandstorm rate was relatively higher in most of the El Niño years, and in most of the La Niña years the rate was relatively lower.     

Air Pollution Effects on Forest Trees in Balikesir,Turkey

Air pollution has become an actual problem in Balikesir because of rapid urbanisation and increasing of the polluting sources. Air pollutionproblems occur under the unfavorable meteorological conditions which increase in frequency of occurrence in winter due to use of low quality lignite coals for heating. The `Protection of Air Quality' in Turkey dated 1986 is based on the human health criteria. But the critical limit values are lethal for the forest trees as far as SO₂ is concerned. The field observations showed that leaves of the trees have yellow spots indicating acid burns in Balikesir. This study aims at determining the relationships between the SO₂ concentrationsin the air under selected climatic conditions, and the effects of air pollution on forest trees in Balikesir. Samples of leaves were collected from the City Parks in Balikesir, Deirmenboaz forested area located 10 km far fromBalikesiron the Balikesir-Bursa highway, and from the forestation areas near the Balikesir-Edremit highway. Sulfur contents of the leaves were very high especially in the city (2650–5300 g m^-3).Samples from other areas had values lower than this range but above the usual values (850–3612 g m^-3). The diameter increments of the trees were found to be lower and these results clearly showed the adverse impacts. Negative correlations were found between these sulfur concentrations and the daily mean temperatures and wind speeds. Positive correlation was seen between these concentrations and pressures, humidities. Emission sources must be controlled in order to safeguard the forests which protects the soil, facilitate water production, assimilate carbon dioxide in air and produce oxygen. It must be considered that the problems are not only regional but have a global identity.     

Long Term Trends in Concentration of Major Pollutants (SO<Subscript>2</Subscript>, CO,NO, NO<Subscript>2</Subscript>, O<Subscript>3</Subscript> and PM<Subscript>10</Subscript>) in Prague – Czech Republic (Analysis of Data Between 1992 and 2005)

To assess the effect of changes in traffic density and fuels used for heating at the beginning of the 1990s, 1992–2005 monthly averages of PM₁₀, SO₂, NO₂, NO, CO and O₃ from Prague, the Czech capital, were analyzed together with long term trends in emissions of major pollutants, fuel consumption and number of vehicles registered in Prague. The data from all monitoring stations were retrieved from the database of the state automated monitoring system. Correlation coefficients between ambient monthly averaged temperature and all pollutants of concern showed distinct seasonal trends. The results showed that while SO₂ and to some extent also CO concentrations dropped namely in the first half of the analyzed period (1992–1997) as a result decreased fossil fuel consumption for local heating, the behaviour of other pollutant concentrations followed a different pattern. PM₁₀ concentrations decreased during the beginning of the 1990s but showed a sign of increase after 2000. Concentrations of ozone and NO₂ did not reveal any significant change throughout the whole studied period. It can be concluded that during the studied period traditional urban sources of pollution, such as coal and oil combustion, lost their importance but were simultaneously substituted by pollutants from automotive transport (namely PM and NO₂) making the problem of air quality even worse.     

Ozone Episode in the Milan Metropolitan Area A Comparative Evaluation of UAM-V and CALGRID Models

Data from an ozone episode (2–5 June, 1998) in the Milan metropolitan area were used for an application of two photochemical grid models: UAM-V and CALGRID. To assure a fair comparison, the models were run on the same domain and grid size, with same source emission inputs, CALMET diagnostic meteorology, and initial and boundary conditions taken from air quality data and literature values. Hourly emissions were derived from the AutoOil-II programme inventory except for on-road mobile source emissions; a new traffic emission inventory, based on both COPERT II methodology and road classification has been developed. NO_x and O₃ concentration results were compared to local network monitoring data. Results indicate that both models predict the highest ozone values along the north-east direction and are able to reproduce the ozone daytime trend though differences can be found between the two models on ozone spatial distribution. Average normalised bias for both models is about 50%, peak daily ozone concentrations are underestimated, with simulated peak shapes broader than the observed ones and a temporal shift between the two models. Night-time concentration levels of pollutants were not successfully reproduced due to an incorrect parameterisation of vertical turbulence calling for further work.     

Comparison of percolation to batch and sequential leaching tests: Theory and data

Leaching tests are becoming more relevant in assessing solid waste material, particularly with respect to groundwater risks. In the field, water infiltration is the dominant leaching mechanism, which is simulated in the lab with batch and column tests. In this study, we compared percolation, through analytical solutions of the advection–dispersion equation, to laboratory batch and sequential leaching tests. The analytical solutions are supported with comprehensive data from various field and laboratory leaching of different solutes from waste materials and soils collected in long-term joint research projects funded by the German Federal Ministry for Education and Research and the Federal Environment Agency. The comparison of theory and data is facilitated if concentrations and cumulative release are plotted versus the liquid–solid ratios (LS). Both theory and data indicate that leaching behaviour is independent of duration and physical dimensions of the leaching tests. This holds even if field lysimeters are compared to laboratory columns of different size, different flow velocities as well as different contact times. In general, laboratory batch tests over predict effluent concentrations (for LS < K_d). Leaching of solutes from solid samples of certain materials (e.g. chloride from incineration ashes or sulphate from demolition waste) in column and lysimeter tests compares very well and agrees with the analytical solutions. Overall, reproducibility and agreement with theory of column tests are better than batch tests, presumably because the latter are prone to artefacts (e.g. in liquid–solid separation steps). Theory and data fit surprisingly well, despite the fact that the theory is based on the local equilibrium assumption; non-linear sorption and chemical reactions in the solid waste materials are not considered.     

Reporting central tendencies of chamber measured surface emission and oxidation

Methane emissions, concentrations, and oxidation were measured on eleven MSW landfills in eleven states spanning from California to Pennsylvania during the three year study. The flux measurements were performed using a static chamber technique. Initial concentration samples were collected immediately after placement of the flux chamber. Oxidation of the emitted methane was evaluated using stable isotope techniques. When reporting overall surface emissions and percent oxidation for a landfill cover, central tendencies are typically used to report “averages” of the collected data. The objective of this study was to determine the best way to determine and report central tendencies. Results showed that 89% of the data sets of collected surface flux have lognormal distributions, 83% of the surface concentration data sets are also lognormal. Sixty seven percent (67%) of the isotope measured percent oxidation data sets are normally distributed. The distribution of data for all eleven landfills provides insight of the central tendencies of emissions, concentrations, and percent oxidation. When reporting the “average” measurement for both flux and concentration data collected at the surface of a landfill, statistical analyses provided insight supporting the use of the geometric mean. But the arithmetic mean can accurately represent the percent oxidation, as measured with the stable isotope technique. We examined correlations between surface CH₄ emissions and surface air CH₄ concentrations. Correlation of the concentration and flux values using the geometric mean proved to be a good fit (R² = 0.86), indicating that surface scans are a good way of identifying locations of high emissions.     

Three-Dimensional Numerical Simulation of Air Pollutant Dispersion in Street Canyons

The PHOENICS Computational Fluid Dynamics (CFD) software package has been used with a standard k- turbulence model to simulate the three-dimensional dispersion of air pollutants in an urban street canyon. In all cases, a vortex was formed within the street canyon, characterized by updrafts near the upwind buildings and down-drafts near the downwind buildings. Contours of pollutant concentrations over a transverse vertical plane at mid-canyon show pollutants circulating within the vortex, with higher concentrations at the leeward face than at the windward faces, and higher concentrations above downwind buildings than above upwind buildings. Longitudinal distributions of pollutant concentrations at leeward and windward faces are characterized by higher concentrations at mid-block and lower concentrations at the ends. These results agree qualitatively with previous wind tunnel findings such as those of Hoydysh and Dabberdt (1988) and Wedding et al. (1977). The results also suggest that the k- turbulence model is satisfactory for simulating the effect of turbulence on dispersion of pollutants in street canyons     

Accumulation of pollutant nitrogen in calcareous and acidic grasslands: Evidence from N flux and 15N tracer studies

Semi-natural calcareous and acidic grasslands are known to be sensitive to increased atmospheric N deposition. However, the fate of pollutant N within these systems is unknown. This paper reports on the first studies to determine the fate of added N within a calcareous and an acidic grassland subject to long-term simulated enhanced N deposition. Intact soil/turf cores were removed from field plots treated for six years with enhanced N deposition (ambient +0, +35 and +140 kg N ha^–1 year^–1). Cores were inserted into lysimeters and output fluxes of N were monitored in detail. Complete N budgets—calculated from the N flux data—showed considerable accumulation of N within the treated grasslands, up to 76% and 38% of pollutant N in the calcareous and acidic grasslands respectively. In the second study, the short-term (21 day) fate of pollutant N was determined by tracing ¹⁵N labelled ammonium nitrate (+35 kg N ha^–1 year^–1) though the acidic and calcareous lysimeters into plant, soil and leachate pools. Up to 91% and 59% of ¹⁵N was recovered in soils and vegetation of the calcareous and acidic grasslands respectively, with negligible amounts recovered in soil extractable ammonium and nitrate (<0.3%) and in leachate (<0.02%). This rapid short-term immobilisation of pollutant N supports the long-term accumulation of the element calculated from the N flux study.     

Mathematical modeling of MSW combustion and SNCR in a full-scale municipal incinerator and effects of grate speed and oxygen-enriched atmospheres on operating conditions

The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathematical modeling and accurate prediction of pollutant emissions. In this paper, mathematical modeling methods for both solid and gaseous phases were employed to simulate the operation of a 450 t/d MSW-burning incinerator to obtain detailed information on the flow and combustion characteristics in the furnace and to predict the amount of pollutant emissions. The predicted data were compared to on-site measurements of gas temperature, gas composition and SNCR de-NO_X system. The major operating conditions considered in this paper were grate speed and oxygen concentration. A suitable grate speed ensures complete waste combustion. The predictions are as follows: volatile release increases with increasing grate speed, and the maximal value is within the range of 700–800 kg/m² h; slow grate speeds result in incomplete combustion of fixed carbon; the gas temperature at slow grate speeds is higher due to adequate oxygenation for fixed carbon combustion, and the deviation reaches 200 K; NO_X emission decreases, but CO emission and O₂ concentrations increase, and the deviation is 63%, 34% and 35%, respectively. Oxygen-enriched atmospheres promote the destruction of most pollutants due to the high oxygen partial pressure and temperature. The furnace temperature, NO production and CO emission increase as the oxygen concentration increases, and the deviation of furnace exit temperature, NO and CO concentration is 38.26%, 58.43% and 86.67%, respectively. Finally, oxygen concentration is limited to below 35% to prevent excessive CO and NO_X emission without compromising plant performance. The current work greatly helps to understand the operating characteristics of large-scale MSW-burning plants.     

Air Quality in Major Portuguese Urban Agglomerations

This paper presents some recent research work that has beendeveloped for the major Portuguese agglomerations. Threemain topics are developed: the methodology used in Portugalto limit agglomerations (as they are defined by theEuropean Air Quality Framework Directive 96/62/EC), thepreliminary assessment of the air quality levels in themost densely populated agglomerations over the last fiveyears and their influence on the air quality levels acrossthe country (a requirement by Directive 96/62/EC), and theuse of an air quality index to raise public awareness aboutair quality levels. It is concluded that particulate matteris the critical pollutant in Portuguese populated urbanareas. In Lisbon and Oporto, based in 1999 data, in allmonitoring stations, the daily average limit value of 50g m^-3 for particulate matter (PM₁₀) isexceeded more times during a year period then allowed byDirective 99/30/EC. In the same areas, nitrogen dioxideconcentrations are above the annual limit value of 40g m^-3 for the protection of human health set byDirective 99/30/EC, and influence pollution concentrationswithin a few tens of kilometres surrounding the urbanareas.     

The Effects of Three Thermo Electric Power Plants on Yerkesik-Denizova Forests in Mugla Province (Turkey)

Mugla is a city that is located in the southwest part of Turkey. Three thermo-electric power plants called Yatagan (3 × 210 MW) and Yenikoy (2 × 210 MW)and Kemerkoy (Gokova, 3 × 210 MW) havebeen constructed in this region and also have begun operation in 1982 – 1983 – 1984 (three units), in 1988 and in 1995, respectively. The Pinus brutia forests in Yerkesik–Denizova region have been under the common effects of Yenikoy and Yatagan thermo-electric power plants. Therefore, these Pinus brutia forests have startedto dry in groups since 1988. In addition, Kemerkoy thermo-electric power plant, began operation in 1995.Polluting gases arrived in Denizova-Yerkesik throughKoca Stream Valley Forests.Increasing quantities of polluting gases and especially SO₂ have dried the trees in large amounts in this 1650 ha forestland area. YataganThermo-electric power plant has caused drying of Pinus brutia in Bencik Mountain, which was on the south in 1984–1985. The same phenomenon was seen in Denizova-Yerkesik Forest in 1999–2000. It was observed that sulphur content was varying between 4218–6676 ppm at the Pinus brutia needle samples taken in this region on 16 December 2000. Sulphur contents were correlated with the age of needle (1–2 yr old), density of yellow stains on the needles and amount of drying needles. Particularly in 1996–2000 period, the destruction of chlorophyll in needles due to the impacts of SO₂ was also correlated with narrowing of the annual rings from one year to another. The narrowing ratio of yearly rings reached 60–504% for 94–95 yr old, and 375–661% for 58–63 yr old Pinus brutia trees during the 1986–1990, 1991–1995 and 1996–2000 periods.All these results clearly showed that the decrease in the chlorophyll content in needles under the effect of air pollution caused important reduction in the raw timber production and its inputs to the economy. In other words, drying due to increased ecological sensitivity or direct hazard of pollutants emitted by the power plants and cutting of trees have been notably increased in the region. This has created serious economic losses.     

Analysis of the St. Petersburg Traffic Data using the OSPM Model

Since October 1998 two DOAS instruments were installed at the level of the first floor and at the top of a building located in St. Petersburg at Pestelya Street. The collected datacovers the time period of December 1998–March 2001, and include concentrations of benzene, toluene, NO and NO₂, ozone and SO₂. There is also an additional information about the traffic intensity and meteorological conditions. The results of the analysis of this data set, using the OSPM model, are presented here with the goal to understand the features of the air pollution dispersion in this street canyon and to analyse the information about the emission factors of the vehicles. In particular, the model results are used for the solution of the inverse problem of reconstructing the emission factors from measured concentrations. The results obtained indicate that most of the concentrations are well inside the Russian standards with the only exception of NO₂ (mean and 98-th percentile are equal to 57.8 and 119.2 g m^-3 for the street level). The same values for benzene are 18.5 and 62.6, respectively. Emission estimates show that there is a possibility that the NO_x and benzene basic emission factors recommended by the Russian national guidelines could result in overestimating the traffic emissions. These considerations are supplemented with the model sensitivity tests carried out in connection with the problem of predictability of NO₂ concentrations in the street canyon. Tests indicate that NO₂ concentrations are not very sensitive to NO_x emissions because of the usually low urban background ozone levels.     

Effects of bed material size distribution, operating conditions and agglomeration phenomenon on heavy metal emission in fluidized bed combustion process

This study investigates the effects of the bed material size distribution, the operating conditions and the agglomeration/defluidization phenomenon on the heavy metal pollutant emissions in the combustion process. After defluidization, the emission concentration of heavy metals increased, because Na may form a low melting eutectic material that enhances bed material adherence. The emission of Cd increased when the feed simulated urban residues contained sodium; however, the presence of Na had no significant effect on the emission of Cr. Furthermore, the Cd emission concentration was low when the material had a Gaussian distribution; however, the decreases in the Cd emission when the bed material had narrow, binary or flat distributions were not significant. The heavy metal Cr showed the same trend. In addition to the operating parameters, the bed material size distribution may influence the heavy metal emissions during combustion processes.     

Near‐Surface Disposal Performance Assessment: Modeling Monthly Precipitation and Temperature in Various Climate Environments

A more stable and extensive analysis of climate is necessary to simulate long‐term impacts associated with climate change. The exponential dispersion model (EDM) family of distributions, a popular choice when characterizing precipitation levels and temperature in different climate environments, is being considered for its applicability to near‐surface disposal performance assessments. In this study, the EDM family is examined to determine if there is a preferred distributional form within the family for these parameters using data from two sites whose climate environments are quite different. One site is in a semiarid environment and the other is in a humid environment. In addition, the merits of selecting a different distributional form to represent each calendar month of precipitation and temperature data are explored. Results show that the gamma distribution was most often determined to be the best fit to recorded precipitation data. When considering temperature, however, the Weibull distribution proved to be a better fit. These results suggest that greater precision may be possible when temperature and precipitation serve as inputs to modeling activities, if these parameters are allowed to be represented by different distributions and derived by calendar month. Ultimately, the approach provides a more far‐reaching examination of historical records and provides an increase in confidence, when used in the evaluation of long‐term climate impacts associated with near‐surface disposal facilities. © 2013 Wiley Periodicals, Inc.