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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
411

Index kvality ovzduší jako nástroj pro hodnocení celkového znečištění ovzduší / Air quality index - a tool for ambient air quality assessment

Stráník, Vojtěch January 2013 (has links)
7 Abstract Air pollution has a great impact on human health, with acute consequences possibly resulting even in death. It is therefore important to inform the public about up-to-date air quality and its impact on health in a simple and easily undestandable way. Air quality indices seems to be ideal for this purpouse, but there is large variety of them. In this master thesis, the air quality index most suitable for the capital city of Prague has been searched for. A comparison of the following indices has been carried out based on available data: of following indicies based on avaible data (concentration of O3, PM10, NO2, SO2 a CO): Air Quality Index, Aggregate Air Quality Index, Revised Air Quality Index, Common Air Quality Index a Pollution Index and their modifications according to european standards. As a criterion of aptness of a particular index, a degree of correlation between the index itself and corresponding health problems (daily count of deaths, daily count of deaths caused by diseases of the respiratory system, daily count of deaths caused by diseases of circulatory system, daily count of hospitalization caused by diseases of the respiratory system, daily count of hospitalization caused by diseases of circulatory system) of the local population has been chosen. This relationship was verified...
412

Applications of stable carbon and oxygen isotope analysis to some aspects of coastal environmental change

Twiddy, Edward James January 1996 (has links)
No description available.
413

Health effects of air pollution in Iceland : respiratory health in volcanic environments

Carlsen, Hanne Krage January 2014 (has links)
Air pollution has adverse effects on human health. The respiratory system is the most exposed and short-term changes in air pollution levels have been associated with worsening of asthma symptoms and increased rates of heart attacks and stroke. Air pollution in cities due to traffic is the major concern, as many people are exposed. However, natural sources of air pollution such as natural dust storms and ash from volcanic eruptions can also compromise human health. Exposure to volcanic eruptions and other natural hazards can also threaten mental health. Air pollution has not been extensively studied in Iceland, in spite of the presence of several natural pollution sources and a sizeable car fleet in the capital area. The aim of this thesis was to determine if there was a measurable effect on health which could be attributed to air pollution in Iceland. This aim was pursued along two paths; time series studies using register data aimed to determine the short-term association between daily variation in air pollution and on one hand daily dispensing of anti-asthma medication or the daily number of emergency room visits and emergency admissions for cardiopulmonary causes and stroke. The other method was to investigate if exposure to the Eyjafjallajökull volcanic eruption was associated with adverse health outcomes, either at the end of the eruption, or 6 months later. In paper I time series regression was used to investigate the association between the daily number of individuals who were dispensed anti-asthma medication and levels of the air pollutants particle matter with an aerodynamic diameter less than 10 μm (PM10), nitrogen dioxide (NO2), ozone (O3), and hydrogen sulfide (H2S) during the preceding days. For the study period 2006-9, there were significant associations between the daily mean of PM10 and H2S and the sales of anti-asthma medication 3 to 5 days later. Giving the exposure as the highest daily one-hour mean gave more significant results. Air pollution negatively affected the respiratory health of asthma medication users, prompting them to refill their prescriptions before they had originally intended to. In paper II the main outcome was the number of individuals seeking help at Landspitali University Hospital emergency room for cardiopulmonary disease or stroke. Time series regression was used to identify the lag that gave the best predictive power, and models were run for data for 2003-9 pollutants PM10, NO2, and O3. O3 was significantly associated with the number of emergency hospital visits the same day and two days later in all models, and both for men, women and the elderly. Only emergency hospital visits of the elderly were associated with NO2, and there were no associations with PM10. In paper III the aim was to investigate if the health effects of PM10 were affected by the addition of volcanic ash from the 2010 eruption of Eyjafjallajökull and 2011 eruption of Grímsvötn to PM10 in the capital area. Time series regression of emergency hospital visits and PM10 before and after the Eyjafjallajökull eruption showed that the effect tended to be higher after the eruption, but the results were not significant. Analysis with a binary indicator for high levels of PM10 from volcanic ash and other sources showed that volcanic ash was associated with increased emergency hospital visits. There were no associations with high levels of PM10 from other sources. In paper IV, the health of the population exposed to the ongoing eruption of Eyjafjallajökull in 2010 was investigated thoroughly. Lung function in adults was better than in a reference group from the capital area, though many reported sensory organ irritation symptoms and symptoms of stress and mental unhealth, especially those with underlying diseases. Paper V report the results from a questionnaire study which was carried out six months after the Eyjafjallajökull eruption. The study population comprised a cohort of south Icelanders exposed to the eruption to varying degrees and a reference group from north Iceland. Respiratory and eye symptoms were much more common in south Icelanders than in the reference group, after adjusting for demographic characteristics. Mental unhealth rates had declined considerably. In the studies, we found that urban air pollution and natural particles have short-term effects on anti-asthma medication dispensing and emergency room visits and hospital admissions. Exposure to natural particles in the form of volcanic dust was associated with increased respiratory symptoms in a very exposed population. There were indications that volcanic ash particles were associated with increased emergency hospital visits in the following days. / <p>Statement of collaboration</p><p>This thesis and the work in it have been produced in collaboration between University of Iceland and Umeå University. The thesis was issued and defended at both institutions. Responsible</p>
414

Population exposure to cyanide vapour from gold mine tailings dams

22 June 2011 (has links)
M.Sc. / Atmospheric emissions of dust and chemicals from gold mine tailings are ongoing environmental management issues on the Witwatersrand, where residential areas have developed in proximity to dumps. Residual amounts of cyanide, used as a chemical in the gold extraction process, are deposited with the mineral tailings. This study deals with the evaluation of population exposure to cyanide vapour emitted from gold mine tailings dams, an issue of environmental impact and public health concern. The first part of this study deals with the determination of the emission factors of cyanide vapour from three selected gold mine tailings dams: one under reclamation; one no longer operational; and one fully operational as a slimes deposition site. These three sites are located in the Boksburg area of the Ekurhuleni Metropolitan Municipality. Twelve samples were collected in all: six from the Cason (2628AAL91) mine dump (under reclamation in 2006); four from the ERPM tailings complex [comprising the dormant deposits 4/L/47, 4/L/48, 4/L/49 and 4/L/50, which are north of the N17 national highway; and the 2628ACL1 deposit, which is south of the N17]; and two from the Rooikraal (active) deposition site. All samples were collected in the year 2006. In the second part of the study, the obtained emission factors were used in an Industrial Source Complex dispersion model to measure the degree of population exposure to cyanide vapour for communities that are in proximity to the operational gold mine tailings dams in the Johannesburg Metropolitan Municipality. In the third part, a health risk assessment was carried out for communities in proximity to the selected gold mine tailings dams. The study revealed the average flux (± std. dev.) of Cason to be (4.7 ± 0.8) x 10-7 g m-2 s-1, the average flux of ERPM (3.9 ± 0.6) x 10-7 g m-2 s-1, the average flux of Rooikraal (1.7 ± 0.2) x 10-5 g m-2 s-1. The concentrations of cyanide vapour emitted from the older tailings deposits (sand) that are under reclamation and the dormant slimes dams are very low (and pose little health risk to occupants of adjacent land). However, HCN emission factors from operational tailings dams, which are receiving continuous depositions, are 3 to 80 times higher than the emission factors from dormant mine tailings. Ambient cyanide concentrations near the active tailings deposits may sometimes exceed selected international health standards. The average hourly, daily and annual dispersion model calculations for the Nasrec tailings deposition sites in Johannesburg revealed that 117 938, 18 722 and 8 130 people respectively were exposed to hydrogen cyanide concentrations that were above international (Ontario, Canada) standards. This raises environmental concerns that require institution of cyanide monitoring and setting of emission limits applicable to South African legal and environmental circumstances. These conclusions are based on a small number of emission factor determinations and hence these findings should be regarded as provisional. Further testing and verification are required for emission factors from a larger number of dormant, reworked and active tailings dams.
415

Links between ENSO and particulate matter pollution for the city of Christchurch / Kopplingen mellan ENSO ochaerosoler mindre än 10 μm i Christchurch

Derneryd, Anna January 2006 (has links)
The purpose of the project has been to investigate how synoptic scale climate systems control the frequency of air pollution episodes in the city of Christchurch, New Zealand. The work has been done at the University of Canterbury, New Zealand, and data from the region has been analysed. Air pollution is, during winter time, a growing problem in Christchurch and the project was initiated by the regional environmental legislative body. The first part of the report is on finding relationships on a local-scale between particulate matter concentrations, ground temperature, temperature at 10 meters and wind speed. The data set used in the analysis comes from a monitoring station in St. Albans, situated in the north-east of Christchurch. In the second part, a connection is made thought correlation calculations between the results from the local-scale analysis and the synoptic situation observed over New Zealand during the same period. Two different data sets have been used in the analysis. One data set includes different weather patterns observed over New Zealand and the other data set includes different zonal and meridional circulation indices. A pressure index is also used, the Southern Oscillation Index. On the local-scale, a relationship has been found between the particulate matter concentration and the number of night hours with an inversion present. A correlation also exists between the wind speed and the number of night hours with an inversion present. The connection to the synoptic scale through cluster frequencies and circulation indices was found to be divergent. The cluster frequency analysis indicates on a direct correlation between the Southern Oscillation Index and the air pollution concentration in Christchurch, while the circulation indices analysis indicates on an inverse relationship between the Southern Oscillation Index and the air pollution concentration in Christchurch. / Sammanfattning av ”Kopplingen mellan ENSO och aerosoler mindre än 10 μm i Christchurch” Avsikten med projektet har varit att undersöka om det finns ett samband mellan storskaliga vädersystem (synoptisk skala) och antalet lokalt inträffade händelser med höga halter av luftföroreningar. Arbetet har utförts vid University of Canterbury i Christchurch på Nya Zeeland och mätdata för denna region har analyserats. Luftföroreningar är här ett växande problem, speciellt vintertid, vilket de regionala lagstiftande myndigheterna har identifierat och önskat få utrett. I första delen av rapporten analyseras samband mellan lokala parametrar, så som temperatur vid marknivå och på 10 meters höjd, vindhastighet och koncentrationen av olika luftföroreningar. Data som använts i dessa analyser har uppmätts vid en mätstation placerad i St. Albans, vilken ligger i nordöstra delen av centrala Christchurch. I den andra delen av rapporten beräknas korrelationen mellan resultaten från den lokala analysen och olika synoptiska vädersituationer observerade över Nya Zeeland under motsvarande tidsperioder. Två databaser har använts vid analysen, dels en databas innehållande olika vädersituationer över Nya Zeeland och dels en innehållande olika cirkulationsindex. Dessutom användes också ett lufttrycksindex, ”The Southern Oscillation Index”. Två korrelationer har beräknats i den lokala analysdelen. Dels har ett samband mellan luftföroreningskoncentrationen och antalet timmar med en inversion närvarande nattetid beräknats samt en korrelation mellan vindhastighet och antalet timmar med en inversion närvarande nattetid. Kopplingen till den synoptiska skalan visar på två divergerande resultat. Analys genomförd med olika ”clusters” visar på ett direkt samband mellan ”The Southern Oscillaion Index” och luftföroreningskoncentrationen i Christchurch medan en analys genomförd för circulationsindex visar på ett omvänt samband mellan ”The Southern Oscillation Index” och luftföroreningskoncentrationen i Christchurch.
416

Sensitivity Analysis of the Mesoscale Air Pollution Model TAPM

Hirdman, David January 2006 (has links)
Known problems with the air pollution model, TAPM’s meteorological predictions over the Canterbury Plains, New Zealand, has been its lack of ability to simulate low nocturnal stagnant wind speeds, certain wind field directions as well as greatly overestimating the sensible heat flux. The aim of this thesis has been to reduce these known disagreements along with other meteorological parameters in attempt to optimize TAPM’s predictions for New Zealand conditions. The methodology used to obtain better agreement with observational data during a four-day period (1-4 of August 2000) was to modify certain initial parameters. These parameters were the deep soil volumetric moisture content, the deep soil temperature, the sea surface temperature, the synoptic pressure gradient scaling factor, and to include rain processes or not in the simulations. It is found that including rain processes and increasing the deep soil volumetric moisture content (at least during wintertime) do improve the simulations performance. / Från tidigare studier med luftföroreningsmodellen TAPMs meteorologiska prognoser över Canterburys slätter, i Nya Zeeland, har man funnit problem. Dess brister har bestått i svårigheter att simulera de nattetid svaga och stagnerande vindhastigheter, vissa riktningar i vindfältet samt grov överskattning av det sensibla värmaflödet. Målet med denna rapport har varit att reducera dessa kända avvikelser tillsammans med andra meteorologiska parametrar i ett försök att optimera TAPMs prognoser för förhållandena över Nya Zeeland. Metodiken som används för att uppnå bättre överensstämmelse med observationsdatan från en fyradagarsperiod, 1-4 augusti år 2000, var att modifiera vissa specifika initieringparametrar. Dessa parametrar var den djupgående markfuktigheten, den djupgående marktemperaturen, havsytans temperatur, det synoptiska tryckets skalningsfaktor. Det undersöktes också om man skulle inkludera nederbördsprocesser eller inte i simuleringarna. Resultaten visade att en inkludering av nederbördsprocesser samt en ökning av den djupa markfuktigheten (åtminstone vintertid) verkar förbättra kvalitéten på simuleringarnas resultat.
417

Characterisation of Cape Town brown haze

Walton, Nicola Maria 16 November 2006 (has links)
Faculty of Science School of Geography And Archaeology and Enviromental Studies 9905693x Nicola@crg.bpb.wits.ac.za / The Cape Town brown haze is a brown-coloured smog that is present over the Cape Town atmosphere during the winter months due to the accumulation of gaseous and particulate pollutants. The main aim of this research was to evaluate the impact of atmospheric pollutants to visibility impairment by the brown haze through visibility modelling of major pollution sources around the City of Cape Town. The screening model, VISCREEN, the Plume Visibility model, PLUVUE II and the CALPUFF Modelling System were employed to model the visual impact of emissions from the major sources. Two point sources, Caltex Oil Refinery and Consol Glass, and three area sources, Cape Town Central Business District (CBD), Cape Town International Airport and the townships of Khayelitsha and Mitchell’s Plain were identified as the major sources. An initial screening analysis indicated that emissions from the two industrial sources would be visible and would result in a yellow-brown discolouration of the atmosphere. Detailed modelling using PLUVUE II identified the area sources of Cape Town CBD and the townships to be the significant contributors to visibility impairment over Cape Town. Plume perceptibility is primarily dependant upon particulate emissions while NOx emissions influence the colouration of the atmosphere. CALPUFF was employed to assess the distribution of NOx, SO2 and PM10 concentrations over the area and the associated visibility impairment on a nonhaze (13 August 2003) and haze day (22 August 2003). Pollutant concentrations were considerably reduced on the non-haze day compared to the haze day. The Cape Town CBD was an important source of all the major pollutants with the townships contributing significantly to the aerosol loading over Cape Town. Pollutant concentrations are particularly elevated during the late evening and early morning periods, particularly between 7 am and 8 am. Visibility impairment is greatest on the haze day, particularly over the central Cape Town region and the townships. The greatest reduction in visibility is experienced between midnight and 9 am which corresponds with the periods of elevated atmospheric pollutant concentrations.
418

Ambient air quality monitoring : a comparison between two urban parks in Soweto, South Africa

Valsamakis, Sophia Katerina January 2016 (has links)
A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 14 August 2015 / Soweto is identified as an air pollution hot spot area which is characteristic of poor air quality where ambient air pollutant concentrations frequently exceed the South African Ambient Air Quality Standards. Urban greening programmes are seen as a way for cities to work towards reducing air pollution, offsetting greenhouse gas emissions and improve ambient air quality. The City of Johannesburg embarked on the Greening Soweto project in 2006 where many degraded open spaces were transformed into urban green parks and 6000 trees were planted. The urban parks and trees are believed to serve several environmental benefits; one of which includes the improvement in local ambient air quality. The aim of this research was to assess and compare the local ambient air quality situation at two different urban park types in close proximity, Thokoza Park (older trees) and Petrus Molefe Eco-Park (young trees), in Soweto and establish whether the air pollutants measured at the urban parks were lower compared to the urban background conditions. Furthermore, this study assessed whether the ambient concentrations of the selected criteria air pollutants were within the South African National Ambient Air Quality Standards. Three ambient air quality monitoring campaigns were conducted during the spring (October) and winter (June and July) seasons of 2013 and 2014 with the use of a mobile air quality monitoring station. The findings of this research suggest that urban trees in Thokoza Park and Petrus Molefe Eco-Park has the greatest potential to improve air quality in Soweto mainly through changes in local meteorological conditions, specifically for temperature and wind fields, rather than direct removal of air pollutants. Differences in the concentrations of the air pollutants at the different sites showed a strong relationship with changes in temperature, wind speed and direction and emission source types. A significant difference in air pollutant concentrations between the two urban park types was only found for particulate matter (PM10 and PM2.5) and CO2. In general, lower air pollutant concentrations were recorded at the urban parks compared to the urban background site, particularly during the spring season. This study also suggests that the urban trees could represent a potential O3 sink during the spring and winter seasons and for NOx during the spring season. Exceedances of the South African Ambient Air Quality Standards at the two urban parks were only observed for PM10 and PM2.5 during the winter season of 2014. PM10 and PM2.5 and NOx were identified to be air pollutants of concern at the urban parks in comparison to other criteria air pollutants assessed in this study. Maximum daily concentrations of 255 μg/m3 for PM10 and 126 μg/m3 for PM2.5 and a maximum hourly concentration of 92 ppb for NOx were recorded at the parks during winter season
419

The desulfurization of petroleum compounds using a polymer-supported imidation agent

Matoro, Tshilidzi Benedicta January 2016 (has links)
A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The sulfur removal methods from petroleum products have become an important research topic. Sulfur poisons the catalysts found in vehicles engines and it is also a major air pollutant (Nehlsen, 2005). Recent sulfur specifications require refineries to produce ultra-clean products (Ma et al., 2002). This work aims at exploring a batch adsorptive desulfurization technique using a polymer-supported imidation agent (PI) as an adsorbent. The test was carried out at atmospheric pressure and on two commercial diesel fuels with sulfur contents of 5200 (Case 1) and 670 (Case 2) mg/kg which resembles the feed and outlet streams from the hydrodesulfurization (HDS) reactor respectively. The adsorbent was synthesized according to the procedure described by Shiraishi et al. (2003), BET, FTIR, SEM equipped with EDS and TGA were used for charaterization of the adsorbent. The PI was successfully synthesized and its surface area was 0.5333 m2/g which was incredibly lower than that of the PI synthesized by Fadhel (2010). Hence carbon nanotubes (CNTs) were added to the solution with the aim of improving the sulfur removal efficiency of PI. The obtained results indicated that PI with CNTs yield better results than PI without CNTs. In overall, the lowest sulfur content of 3462 mg/kg (33% removal efficiency) and 26 mg/kg (96% removal efficiency) for Case 1 and Case 2 respectively were obtained. Furthermore, the adsorbents were most effective at lower mixing rates (150 – 400 rpm), longer contact time (30 – 40 hours), practically high adsorbent amount (1 g) and moderate lower temperatures (25 – 50 ºC). The Freundlich adsorption isotherm model was the best fit to the experimental data in both Case 1 and Case 2. The kinetic model that best fitted well the experimental data is the pseudo-second-order model for both Case 1 and Case 2. The kinetic rate constant for Case 2 (4.079 x 10-3g/mg.min) was greater than that for Case 1 (6.75 x 10-5g/mg.min) thus indicating that fuel with low sulfur content has a higher sorption uptake than fuel with high sulfur content. Based on the results obtained in this study, it is suggested that the adsorption of sulfur at high sulfur content fuel is not capable to be used as a complimentary method to the HDS process. On the other hand, at low sulfur content fuel, there is an opportunity for combining this method with the traditional HDS method to achieve ultra-clean fuel. / GR2016
420

The integration of measured, modelled and remotely sensed air quality data and its' impacts on the Highveld.

Bhugwandin, Kubeshnie Naicker 06 February 2014 (has links)
Although a vast number of air quality investigations have been conducted on the Mpumalanga Highveld previously, there has been limited attempt to integrate available datasets from the different methods of air quality monitoring (satellite, insitu and ground-based observations) and modelling. This study compares modelled, satellite and measured data to determine the most accurate estimate of ground level sulphur dioxide (SO2) and nitrogen oxide (NOx) concentrations. The main value of the project comes from the ‘improvement’ of modelled concentration fields using measurements. Measurements only provide information on air quality at isolated places (for example monitoring stations) or at isolated times (aircraft measurements and satellite observations). Dispersion models predict concentrations continually over a wide area. However, models have inherent inaccuracies based on the assumptions made in developing the model and the variability in the input parameters supplied. These can be accounted for or are part of the inherent variability of the model results. This study assists in the refinement of modelled outputs as well as the verification of satellite data using ground-based measured data as a point of reference. In the wake of increasing governance on air pollution, industry has been compelled to account for their impacts on the environment. This study aids industry by proposing a method to quantify their impacts on the environment and possibly on human health. Three datasets from 2003 (modelled, measured and satellite) were integrated using a geographic information system in order to analyse and interrogate the data and produce an integrated set of data, maps of potentially sensitive ecosystems and maps of potential exposure to poor air quality of sensitive population groupings. The results of the study have shown that although the concentration value for the NO2 iv tropospheric column is greater than the values observed on the ground there is a good correlation between measured observations and SCIAMACHY retrievals. The sample size was too small to indicate a statistically significant bias. The results from the validation of the CALPUFF model indicate with respect to SO2 predictions that themodel is only reliable for 62% of the time within the United States Environmental Protection Agency’s model performance guideline of acceptance i.e. predictions within a factor of 2, and for NO2 the predictions are reliable for only 50% of the time. There is also no constant value by which the model under or over predicts. The cumulative distribution function graphs illustrate that the CALPUFF model predicts the highest values from the bulk of the distribution rather that the tail of the distribution where the extremes lie. This could possibly account for the large variance between measured and modelled outputs. The results of identifying areas of potential harm from SO2 emissions reveal that hotspots for high to very high risk to human health occur around all power stations. Generally the category of high risk around power stations seems to be located in areas with population agglomerations between 0-1 000 per km2 and 2001- 5000 per km2. Several high risk areas for potential harm to ecosystems from SO2 emissions can be seen on the Highveld with a large spatial extent around Kendal, Matla and Kriel power station. Approximately 871 wetlands fall within the high risk areas. The vegetation risk map indicates a high risk to several grassland and bushveld types. Model results for this study indicate no potential risk to human health from emissions of NO and subsequent conversion to NO2 in the atmosphere.

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