Dissertations / Theses on the topic 'Mercury Environmental aspects Measurement'
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1
Williams, Chavon R. "A National survey of Mercury levels in South Africa's water management areas." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8674_1298356510.
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This study forms part of a broader project co-funded by the Water Research Commission (WRC), and CSIR Parliamentary Grant (PG) and Strategic Research Panel (SRP) research grants, aimed at surveying selected water resources within the 19 Water Management Areas in South Africa. Furthermore, it aims at determining the concentrations of Hg and MeHg in various environmental compartments collected from priority water resources, to identify the potential Hg hotspots, and to assess the degree of compliance with national and international guidelines. Mercury concentrations in the environment have increased globally and this has caused much anxiety in terms of the adverse effects it has on aquatic ecosystems, their organisms, and the communities they sustain. Human health risks associated with the consumption of fish elevated containing Hg concentrations have received minimal attention particularly in South Africa. It is imperative that any potential adverse impacts of Hg on aquatic ecosystems, and the subsequent impacts on human health, be investigated.
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Speelman, Wilcot John. "Modelling and measurement of radon diffusion through soil for application on mine tailings dam." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=init_4954_1178282946.
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Radon has been identified as an important factor that could result in a health hazard by studies all around the world. The health risks can be minimised by preventive measures where radon is highly concentrated as in some mines and homes. Measuring and modelling the radon concentrations in the mine dump soil, can help to deduce the radon flux to identify the problem areas for rehabilitation especially in the cases of gold and uranium mine tailings. Rehabilitation in those cases usually consists of a multilayer cover of solids like crushed rock or clay. A passive method incorporating electret technology was used in this study to determine the radon emanation coefficient of the soil. This investigation also describes the modelling of a depth profile with respect to the radon activity concentration to understand from how deep radon might be migrating, as well as the effect of different diffusion lengths.
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Nelson, Sarah J. "Winter Contribution to Annual Throughfall Inputs of Mercury and Tracer Ions at Acadia National Park, Maine." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/NelsonSJ2007.pdf.
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Sauer, Robert Eugene Jr. "Development and use of saltmarsh mesocosms in studies of sedimentary mercury transformation." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19608.
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Liang, Peng. "The effects of mariculture on mercury distribution, speciation and transformation in the aquatic system around Hong Kong coastlines." HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1291.
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Legrand, Melissa. "Evaluation of methodology for mercury exposure assessment with field and laboratory studies." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85932.
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The threat of environmental mercury (Hg), particularly methylmercury (MeHg), exposure to the health of humans has been well documented. Thus, it is important to monitor exposure and body burden for public health protection. The first objective of this thesis was to characterize the risk of Hg exposure in two Canadian coastal communities: Grand Marian (n = 91) and St. Andrews/St. Stephen (n = 52), New Brunswick, Canada, using dietary questionnaires and hair analysis. Average Hg intakes and body burden were below the most conservative guidelines. We attributed these results to the low Hg concentrations found in the species commonly consumed: haddock, canned tuna, lobster and pollock (all below 0.2 mg/kg). The analytical method employed to determine Hg in hair, cold vapor atomic absorption (CV-AAS), required a bundle of 100-150 hair strands and involved lengthy chemical digestion procedures which reduce throughput. Direct solid introduction techniques minimize these weaknesses. Our second and third objectives were to evaluate two such methods: (1) combustion, gold amalgamation, atomic absorption spectrometry (C-GA-AAS) and (2) laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for measuring total Hg in single hair strands. Hair samples with a wide range of Hg exposure were obtained from communities. A 1:1 relationship was observed between C-GA-AAS and the established CV-AAS for analysis of 1-cm hair segments. Additionally, the average relative standard deviation (RSD) of Hg between hair strands within an individual was 6.5 +/- 2.8%, thus justifying the use of a single hair strand for biomonitoring. With a limit of quantification of 0.10 ng of total Hg, a single hair strand with average weight of 0.5 mg and Hg concentrations of 0.2 mg/kg can be measured routinely. Using LA-ICP-MS, we showed that a single laser shot can sample hair material within 50 mum along a single hair strand which is equivalent to less than one day of
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Klaus, Jaclyn Elizabeth. "In situ measurement of mercury ecotoxicological effects on stream periphyton in southwest Ohio." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1409918494.
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Merritt, Karen A. "Mercury Dynamics in Sulfide-Rich Sediments: Geochemical Influence on Contaminant Mobilization and Methylation within the Penobscot River Estuary, Maine, USA." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/MerrittKA2007.pdf.
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Basu, Niladri. "Neurochemical biomarkers to evaluate mercury toxicity in mink." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85882.
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Mercury (Hg) is a toxicant of global concern, but few strategies exist to evaluate its biological effects on the ecosystem. Piscivorous wildlife, such as mink (Mustela vison), are particularly at risk because they can bioaccumulate Hg to concentrations known to impair neurological systems. Given that biochemical changes in the brain precede functional and structural impairments, I evaluated the use of neurochemicals as early-warning biomarkers of Hg toxicity in mink. Initial studies demonstrated that neurochemical biomarkers could be measured from mink carcasses collected from the field, as long as factors such as storage temperature and freeze thaw cycles were accounted for. To determine if Hg could directly impair neurochemicals in mink, an in vitro study demonstrated that Hg (HgCl2 and MeHg) could inhibit radioligand binding to the muscarinic cholinergic (mACh) receptor in the cerebellum and cerebral cortex regions of the brain. By analyzing whole brains collected from wild mink, it was demonstrated that a significant positive correlation existed between concentrations of brain Hg and levels of mACh receptors. These field observations were confirmed by results from a controlled methyl Hg (MeHg) feeding trial in captive mink, whereby sub-chronic exposure of mink to 0.5 - 2 ppm MeHg (ecologically relevant levels) resulted in significant increases in acetylcholinesterase activity and mACh receptor levels in specific brain regions. Collectively, these results demonstrated that exposure of mink to environmentally realistic concentrations of Hg can be related to alterations in neurochemicals at multiple tiers of biological organization. Given the importance of a functional nervous system in wildlife health, the physiological and ecological significance of these findings need further exploration. The results demonstrate that neurochemical approaches may be novel biomarkers to assess the ecotoxicology of Hg, and by extension, other pollutants o
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Manavhela, Ramudzuli Fijiant. "In-situ measurements of radon concentrations in soil gas at a site on the Cape Flats." Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_2407_1242371669.
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Measurements of radon (²
²
²
Rn) concentration in soil gas are routinely used to locate geological fault zones. This study was undertaken to investigate the systematic effects that influence radon soil-gas measurements, in preparation for the first such fault zone measurements in South Africa.
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Gerber, Nicolas Economics Australian School of Business UNSW. "Biodiversity measurement, species interactions and sustainability." Awarded by:University of New South Wales. School of Economics, 2006. http://handle.unsw.edu.au/1959.4/26796.
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Throughout the last two decades, biodiversity has been increasingly acknowledged as a valuable asset. However there are numerous challenges to managing the asset. Firstly, there is no universally accepted measure of biodiversity per se. As a consequence, rather than measuring the intrinsic value of biodiversity the focus has typically shifted to valuing biodiversity services. Secondly, biodiversity issues should not be considered in a vacuum, but rather alongside general natural resource management problems. Conservation agencies and regulators alike would greatly benefit from more transparent biodiversity targets for conservation policies and natural resource management. This thesis makes a number of contributions to meet these challenges including measuring biodiversity, modelling diverse ecosystems and considering biodiversity outcomes in the management of an environmental resource. To value biodiversity, it is essential to measure it. Focusing on pairwise genetic dissimilarities at the species level, this thesis develops two models for measuring biodiversity. An axiomatic diagnosis of the existing and new measures is presented. This comparison suggests that the adequate biodiversity measure depends on the context. The diversity measures describe the biodiversity catalogue available at a given point in time. Modelling biodiversity is important for forecasting the impact of conservation decisions and understanding the future value of biodiversity. The importance of each species, however, depends on its role in the ecosystem as well as its genetic diversity. The interactions between species are therefore investigated and described, using a new model built around CES production functions. Three existing models based on predator-prey equations are extended to the multi-species case. These interaction models provide the necessary link for biodiversity maintenance over time. The four models are compared using simulations and an axiomatic approach. This approach shows that the new model performs well, offers the flexibility required to describe different types of ecosystems and is less data intensive. Finally, a case study of natural resource exploitation is presented, illustrating the idea that biodiversity loss can have direct economic implications in natural resource management. The model shows the impact of market structures on the extraction path of the resource and the distribution of the resource rent.
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Barst, Benjamin Daniel. "Hepatotoxicity of Mercury to Fish." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc31525/.
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Tissue samples from spotted gar (Lepisosteus oculatus) and largemouth bass (Micropterus salmoides) were collected from Caddo Lake. Gar and bass livers were subjected to histological investigation and color analysis. Liver color (as abs at 400 nm) was significantly correlated with total mercury in the liver (r2 = 0.57, p = 0.02) and muscle (r2 = 0.58, p = 0.01) of gar. Evidence of liver damage as lipofuscin and discoloration was found in both species but only correlated with liver mercury concentration in spotted gar. Inorganic mercury was the predominant form in gar livers. In order to determine the role of mercury speciation in fish liver damage, a laboratory feeding study was employed. Zebrafish (Danio rerio) were fed either a control (0.12 ± 0.002 µg Hg.g-1 dry wt), inorganic mercury (5.03 ± 0.309 µg Hg.g-1 dry wt), or methylmercury (4.11 ± 0.146 µg Hg.g-1 dry wt) diet. After 78 days of feeding, total mercury was highest in the carcass of zebrafish fed methylmercury (12.49 ± 0.369 µg Hg.g-1 dry wt), intermediate in those fed inorganic mercury (1.09 ± 0.117 µg Hg.g-1 dry wt), and lowest in fish fed the control diet (0.48 ± 0.038 µg Hg.g-1 dry wt). Total mercury was highest in the viscera of methylmercury fed zebrafish (11.6 ± 1.86 µg Hg.g-1 dry wt), intermediate in those fed inorganic diets (4.3 ± 1.08 µg Hg.g-1 dry wt), and lowest in the control fish (below limit of detection). Total mercury was negatively associated with fish length and weight in methylmercury fed fish. Condition factor was not associated with total mercury and might not be the best measure of fitness for these fish. No liver pathologies were observed in zebrafish from any treatment.
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Brinkmann, Lars, and University of Lethbridge Faculty of Arts and Science. "Mercury biomagnification in the upper South Saskatchewan River Basin." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2007, 2007. http://hdl.handle.net/10133/742.
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In this thesis mercury concentrations in biota of the upper South Saskatchewan River Basin are assessed in three non-industrialized systems. Mercury levels in large sport fish (northern pike, walleye, lake trout) frequently exceeded the consumption limit of 0.5ppm. Goldeye and mooneye of the Oldman River and lake whitefish of Waterton Lakes were below 0.5ppm total mercury. Agricultural and urban effluents constituted no sources of significant mercury loadings to the Oldman River. A doubling of mercury biomagnification factors between longnose dace and their food suggests bioenergetic heterogeneity of these fish along the river gradient. Basin-specific mercury levels were detected for the upper and middle basins in Waterton Lakes, and are associated with food web characteristics, and fish bioenergetics. High mercury levels in a new reservoir were in part attributed to increased loadings from flooded soils, as is commonly observed, but also to bioenergetic constraints and growth inefficiency as a result of non-piscivory of this population.xiii, 130 leaves : ill. ; 29 cm. --
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Nordin, Anders. "On the chemistry of combustion and gasification of biomass fuels, peat and waste : environmental aspects." Doctoral thesis, Umeå universitet, Kemiska institutionen, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-110672.
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Chang, Michael Eppard. "Inverse derived ozone precursor emissions for Atlanta, Georgia." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/26280.
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Dewus, Michael A. "Determination of household radon air and water concentrations for selected homes in east-central Indiana, utilizing activated charcoal canister and liquid scintillation techniques." Virtual Press, 1988. http://liblink.bsu.edu/uhtbin/catkey/544007.
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This is a study of radon concentration levels in the air and water of homes in East-Central Indiana. The results of a survey of 69 homes in which both an air and water sample were analyzed for radon concentrations will be described; all homes in the survey derived their water sample from a well at the home site. Activated charcoal canisters were exposed in homes for two to three days; radon concentration levels in the air samples were then determined following the EPA procedures described by Gray and Windham (1). Radon concentrations in water were determined by the liquid scintillation method according to protocol utilizing the techniques described by Pritchard and Gesell (2). A questionnaire was completed by each participant which provided information such as home construction type, material, and location. Radon concentration results and questionnaire data were entered into a database; database searches were then conducted in order to establish conclusions associated with the study.(1) D.J. Gray and S.T. Windham, EERF Standard Operating Procedures for RN-222 Measurement Using Charcoal Canisters, EPA 520/5-87-005, (June 1987)(2) H.M. Pritchard and T.F. Gesell, Health Physics 33, 577, (1977).Department of Physics and Astronomy
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Moore, Adam. "An Empirical Study of Particulate Matter Exposure for Transit Users at Bus Stop Shelters." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/870.
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Congested traffic corridors in dense urban areas are key contributors to the degradation of urban air quality. While waiting at bus stops, transit patrons may be exposed to greater amounts of vehicle-based pollution, including particulate matter, due to their proximity to the roadway. Current guidelines for the location and design of bus stops do not take into account air quality or exposure considerations. This thesis provides a unique contribution to roadside air quality studies and presents an innovative method for the consideration of bus shelter placement. Exposure to roadside pollutants is estimated for transit riders waiting at three-sided bus stop shelters that either: 1) face roadway traffic, or 2) face away from roadway traffic. Shelters were instrumented with particulate matter monitoring equipment, sonic anemometers for wind speed and direction, and vehicle counters capable of categorizing vehicles by length. Temperature and relative humidity were gathered from a nearby monitoring station. Data were collected for two different days at three shelters during both the morning and afternoon peak periods for a total of eleven data periods. Bus shelter orientation is found to significantly affect concentration of four sizes of particulate matter: ultrafine particles, PM1, PM2.5, and PM10. Shelters with an opening oriented towards the roadway were observed to have significantly higher concentrations inside the shelter than outside the shelter. In contrast, shelters oriented away from the roadway were observed to have significantly lower concentrations inside the shelter than outside the shelter. The differences in average particulate matter concentrations are statistically significant across all four sizes of particulate matter studied. Additional correlation and linear regression investigation reveals interactions between particulate concentrations and built environment characteristics, vehicle flow, and weather conditions. Temperature and relative humidity played a large role in the diurnal variation of average concentration levels. In all instances, particulate concentrations were greater during the morning period, often substantially so. Particulate concentrations are shown to vary based on both wind speed and direction. Vehicle flow is correlated with particulate levels, though significance is not consistent. Lagged vehicle flow is demonstrated to be more consistently significant. Regression analysis suggests weather factors such as wind, temperature, and relative humidity explain roughly 70% of particulate variation, while vehicle flow explains less than 6%.
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Chan, Wah-man, and 陳華民. "Application of life cycle analysis (LCA) to consumer product development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31255140.
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Maphoto, Katse Piet. "Determination of natural radioactivity concentrations in soil: a comparative study of Windows and Full Spectrum Analysis." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&.
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In this study, two methods of analysing activity concentrations of natural radionuclides (U, Th and K) in soil are critically compared. These are the Window Analysis (WA) and Full Spectrum Analysis (FSA). In the usual WA method, the activity concentrations are determined from the net counts of the windows set around individual &gamma-ray peaks associated with the decay of U, Th and K. In the FSA method, the full energy spectrum is considered and the measured spectrum is described as the sum of the three standard spectra (associated with U, Th and K, respectively), each multiplied by an unknown concentration. The concentrations are determined from the FSA and correspond to the activity concentrations of U, Th and K in the soil. The standard spectra derived from separate calibration measurements using the HPGe detector, represents the response of the HPGe to a Marinelli sample beaker containing an activity concentration of 1 Bq/kg.
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Ma, Xiaobo, and 馬？波. "Nitrogen flux analysis and its implications for environmental management in Huizhou, China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B30157274.
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Wright, Jeffery Raymond. "Recovery of refrigerant vapor leakage using high pressure psychrometrics." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17258.
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Thornton, Matthew Jaeger. "Modal vehicle activity on freeways and freeway onramps : an assessment of the oxides of nitrogen emissions impacts resulting from changes in vehicle operating mode due to ramp metering systems." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20785.
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Chan, Ka Ming. "The use of the rock shell, thais clavigera, as a biomonitor of tributyltin contamination in Hong Kong and Shenzhen." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/860.
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Joseph, Angelo Daniel. "Radiometric study of soil: the systematic effects." Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6805_1248251582.
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The natural ²
³
â¸U, ²
³
²
Th and â´°
K radioactive content of vineyard soil was measured with an in-situ gamma-ray detector. The activity concentration measured with the in-situ detector are normalized using the laboratory-determined activity concentrations of several samples from the vineyard site. To determine the activity concentration of a particular soil sample, the gamma-ray photopeak detection efficiencies are required. In this work, the detection efficiencies were derived for each soil sample using gamma-ray photopeaks associated with the radionuclide of ²
³
â¸U, ²
³
²
Th present in the sample, and the â´°
K, 1460.8 keV gamma-ray peak, from KCl salt.
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Hazin, Clovis Abrahao. "Release of radon from showers and its influence on the balance of radon indoors." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16638.
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Ahmed, Sauda. "Modeling of Ultrafine Particle Emissions and Ambient Levels for the Near Roadside Environment." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3506.
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Various epidemiological studies have linked exposure to Ultrafine Particles (UFP; diameter< 100 nm) to adverse health impacts. Roadway traffic is one of the major sources of UFPs and heavily influences UFP concentrations in the nearby vicinity of major roadways. Modeling efforts to predict UFPs have been limited due to the scarcity of reliable information on emissions, lack of monitoring data and limited understanding of complex processes affecting UFP concentrations near sources.
In this study continuous measurement of ultrafine particle number concentrations (PNC) and mass concentrations of nitric oxide (NO), nitrogen dioxide (NO2) and PM2.5 was conducted near an arterial road and freeway at different seasons and meteorological conditions and integrated with traffic count data. PNC showed high correlation with NO (r=0.64 for arterial; 0.61 for freeway), NO2 (r=0.57 for arterial; 0.53 for freeway) and NOx (NOx=NO+NO2; r=0.63 for arterial; 0.59 for freeway) and moderate to low correlation with traffic volume (r=0.33 for arterial; 0.32 for freeway) and PM2.5 (r=0.28 for arterial; 0.23 for freeway); respectively; for both sites at 15 minute averages. The PNC-NOx relationship prevailed on a shorter term (15 min), hourly, and throughout the day basis. Both PNC and NOx showed comparatively higher correlation with traffic during the morning period but became lower during evening which can be attributed to the higher boundary layer and wind speeds. The variable meteorology in the evening affects both PNC and NOx concentrations in the same way and the correlation between NOx and PNC is maintained high both during morning (r=0.74 for arterial; 0.69 for freeway), and evening (r=0.62 for arterial; 0.59 for freeway) periods. Thus nitrogen oxides can be used as a proxy for traffic-related UFP number concentration reflecting the effect of both traffic intensity and meteorological dilution.
The PNC-NOx relation was explored for various meteorological parameters i.e. wind speed and temperature. It is found that NOx emission is temperature independent and can be used to reflect the effect of traffic intensity and meteorological dilution. Once the effect of traffic intensity and dilution is removed, the effect of temperature on PNC-NOx ratio becomes important which can be attributed to the variation in PNC emission factors with temperature.
The high morning PNC-NOx ratio found at the arterial road is a result of new particle formation due to lower temperature and low concentration of exhaust gases in the morning air favoring nucleation over condensation. This finding has important implication when calculating emission factors for UFP number concentrations. Thus it can be concluded that roadside concentration of ultrafine particles not only depends on traffic intensity but also on meteorological parameters affecting dilution or new particle formation. High concentrations of ultrafine particle number concentration close to a roadway is expected due to higher traffic intensity , as well as during low wind speed causing low dilution and low temperature conditions favoring new particle formation.
Finally a simplified approach of calculating particle number emission factor was developed using existing and easily available emission inventory for traffic related tracer gases. Using NOx emission factors from MOVES emission model, the emission ratio of PNC to NOx was converted to develop particle number emission factors. NOx was selected as the traffic related tracer gas since the number concentration of particles is closely correlated to NOx, NOx and particles are diluted in the same way and NOx emission factors are available for a variety of traffic situations. To ensure contribution of fresh traffic exhaust, the average of the difference of pollutant concentrations at high traffic condition and background condition was used to calculate PNC-NOX ratio. Using nitrogen oxides to define background and high-traffic conditions and MOVES emission factor for NOX to convert corresponding PNC-NOX ratio, an average emission factor of (1.82 ± 0.17) E+ 14 particle/ vehicle-km was obtained, suitable for summertime. When compared to existing particle number emission factors derived from dynamometer tests, it was found that there exits reasonable agreement between the calculated real world particle number emission factors and emission factors from dynamometer tests.
The calculated emission factor and R-Line dispersion model was tested in predicting near-road particle number concentrations. Although only 23% of the variability in PNC was explained by the dispersion model, 84.33% of the measurements fell within the factor of two envelope. This suggests that there is potential to effectively use these models and thus warrants more in-depth analysis. Finally, a simple map of PNC gradients from major roads of Portland was developed.
The results of this study helped identify proxy-indicators to provide reference values for estimating UFP concentrations and emissions that can be used for simple evaluation of particle concentration near major roadways for environmental and urban planning purposes and to assess expected impact of UFP pollution on population living near roadways exposed to elevated concentrations.
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Gupta, Ankur Kumar. "Measurement of Henry's constants of volatile organic compounds in aqueous solutions using headspace gas chromatography." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/11209.
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Wright, Monica Elizabeth. "An Investigation of Urban Mobile Source Aerosol Using Optical Properties Measured by CRDT/N: Diesel Particulate Matter and the Impact of Biodiesel." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/673.
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Mobile source emissions are a major contributor to global and local air pollution. Governments and regulatory agencies have been increasing the stringency of regulations in the transportation sector for the last ten years to help curb transportation sector air pollution. The need for regulations has been emphasized by scientific research on the impacts from ambient pollution, especially research on the effect of particulate matter on human health. The particulate emissions from diesel vehicles, diesel particulate matter (DPM) is considered a known or probable carcinogen in various countries and increased exposure to DPM is linked to increased cardiovascular health problems in humans. The toxicity of vehicle emissions and diesel particulate emissions in particular, in conjunction with an increased awareness of potential petroleum fuel shortages, international conflict over petroleum fuel sources and climate change science, have all contributed to the increase of biodiesel use as an additive to or replacement for petroleum fuel. The goal of this research is to determine how this increased use of biodiesel in the particular emission testing setup impacts urban air quality. To determine if biodiesel use contributes to a health or climate benefit, both the size range and general composition were investigated using a comprehensive comparison of the particulate component of the emissions in real time. The emissions from various biodiesel and diesel mixtures from a common diesel passenger vehicle were measured with a cavity ring-down transmissometer (CRDT) coupled with a condensation particle counter, a SMPS, a nephelometer, NOx, CO, CO2, and O3 measurements. From these data, key emission factors for several biodiesel and diesel fuel mixtures were developed. This approach reduces sampling artifacts and allows for the determination of optical properties, particle number concentration, and size distributions, along with several important gas phase species' concentrations. Findings indicate that biodiesel additions to diesel fuel do not necessarily have an air quality benefit for particulate emissions in this emission testing scenario. The often cited linear decrease in particulate emissions with increasing biodiesel content was not observed. Mixtures with half diesel and half biodiesel tended to have the highest particulate emissions in all size ranges. Mixtures with more than 50% biodiesel had slightly lower calculated mass for light absorbing carbon, but this reduction in mass is most likely a result of a shift in the size of the emission particles to a smaller size range, not a reduction in the total number of particles. Evaluation of the extensive optical properties from this experimental set-up indicates that biodiesel additions to diesel fuel has an impact on emission particle extinction in both visible and near-IR wavelengths. The B99 mixture had the smallest emission factor for extinction at 532 nm and at 1064 nm. For the extinction at 532 nm, the trend was not linear and the emission factor peaked at the B50 mixture. Results from intensive properties indicate that emissions from B5 and B25 mixtures have Ångström exponents close to 1, typical for black carbon emissions. The mixtures with a larger fraction of biodiesel have Ångström exponent values closer to 2, indicating more absorbing organic matter and/or smaller particle size in the emissions. Additional experimental testing should be completed to determine the application of these results and emission factors to other diesel vehicles or types of diesel and biodiesel fuel mixtures.
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Teama, Doaa Galal Mohammed. "A 30-Year Record of the Isotopic Composition of Atmospheric Methane." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/642.
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Methane (CH4) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO2 (based on a 100 year time horizon). Its atmospheric concentration has more than doubled from the preindustrial era due to anthropogenic activities such as rice cultivation, biomass burning, and fossil fuel production. However, the rate of increase of atmospheric CH4 (or the growth rate) slowed from 1980 until present. The main reason for this trend is a slowdown in the trend of CH4 sources. Measuring stable isotopes of atmospheric CH4 can constrain changes of CH4 sources. The main goal of this work is to interpret the CH4 trend from 1978-2010 in terms of its sources using measurements of CH4 mixing ratio and its isotopes. The current work presents the measurements and analysis of CH4 and its isotopes (δ13C and δD) of four air archive sample sets collected by the Oregon Graduate Institute (OGI). CH4 isotope ratios (δ13C and δD) were measured by a continuous flow isotope ratio mass spectrometer technique developed at PSU. The first set is for Cape Meares, Oregon which is the oldest and longest set and spans 1977-1999. The integrity of this sample set was evaluated by comparing between our measured CH4 mixing ratio values with those measured values by OGI and was found to be stable. Resulting CH4 seasonal cycle was evaluated from the Cape Meares data. The CH4 seasonal cycle shows a broad maximum during October-April and a minimum between July and August. The seasonal cycles of δ13C and δD have maximum values in May for δ13C and in July for δD and minimum values between September-October for δ13C and in October for δD. These results indicate a CH4 source that is more enriched January-May (e.g. biomass burning) and a source that is more depleted August-October (e.g. microbial). In addition to Cape Meares, air archive sets were analyzed from: South Pole (SPO), Samoa (SMO), Mauna Loa (MLO) 1992-1996. The presented δD measurements are unique measured values during these time periods at these stations. To obtain the long-term in isotopic CH4 from 1978-2010, other datasets of Northern Hemisphere mid-latitude sites are included with Cape Meares. These sites are Olympic Peninsula, Washington; Montaña de Oro, California; and Niwot Ridge, Colorado. The seasonal cycles of CH4 and its isotopes from the composite dataset have the same phase and amplitudes as the Cape Meares site. CH4 growth rate shows a decrease over time 1978-2010 with three main spikes in 1992, 1998, and 2003 consistent with the literature from the global trend. CH4 lifetime is estimated to 9.7 yrs. The δ13C trend in the composite data shows a slow increase from 1978-1987, a more rapid rate of change 1987-2005, and a gradual depletion during 2005-2010. The δD trend in the composite data shows a gradual increase during 1978-2001 and decrease from 2001-2005. From these results, the global CH4 emissions are estimated and show a leveling off sources 1982-2010 with two large peak anomalies in 1998 and 2003. The global average δ13C and δD of CH4 sources are estimated from measured values. The results of these calculations indicate that there is more than one source which controls the decrease in the global CH4 trend. From 1982-2001, δ13C and δD of CH4 sources becomes more depleted due to a decrease in fossil and/or biomass burning sources relative to microbial sources. From 2005-2010, δ13C of CH4 sources returns to its 1981 value. There are two significant peaks in δ13C and δD of CH4 sources in 1998 and 2003 due to the wildfire emissions in boreal areas and in Europe.
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Liao, Boshu. "Analytical and numerical analysis of LNAPL migration and LNAPL thickness estimation in unconfined aquifers." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/32846.
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Yazzie, Kimberly Crystal. "Watershed Response to Climate Change and Fire-Burns in the Upper Umatilla River Basin Using the Precipitation Runoff Modeling System." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3127.
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This study provides an analysis of watershed response to climate change and forest fire impacts, to better understand the hydrologic budget and inform water management decisions for present and future needs. The study site is 2,365 km2, located in the upper Umatilla River Basin (URB) in northeastern Oregon. The Precipitation Runoff Modeling System, a distributed-parameter, physical-process watershed model, was used in this study. Model calibration yielded a Nash Sutcliffe Model Efficiency of 0.73 for both calibration (1995-2010) and validation (2010-2014) of daily streamflow. Ten Global Climate Models using Coupled Model Intercomparison Project Phase 5 experiments with Representative Concentration Pathways 4.5 and 8.5 (RCP), were used to observe hydrologic regime shifts in the 2020s, 2050s, and 2080s. Mean center timing of flow occurs earlier in the year in both pre- and post-fire conditions, where there are increased winter flows and decreased summer flows throughout the 21st century. Change in temperature and percent change in precipitation is more variable in the summer than winter increasing over time, with a slight decrease in winter precipitation in the 2080s in RCP 8.5. Temperature increases 1.6°C in RCP 4.5 and 3.3°C in RCP 8.5 by the end of the 21st century. The ratio of Snow Water Equivalent to Precipitation decreases 96% in the 2080s in RCP 8.5 before forest cover reduction, and decreases 90-99% after forest cover reduction. Potential basin recharge and the base-flow index are both sustained throughout the 21st century with slight declines before forest cover reduction, with an increase in basin recharge and increase in base-flows in the 2080s after fire-burns. However, the simulated sustained base-flows and area-weighted basin recharge in this study, do not take into account the complex geologic structure of the Columbia River Basalt Group (CRBG). A more robust characterization and simulation of URB aquifer recharge would involve coupling the PRMS model with a groundwater model in a future study. Although groundwater recharge in the CRBG in the URB is not well understood, the long-term decline of groundwater storage presents a serious environmental challenge for the Confederated Tribes of the Umatilla Indian Reservation and communities in the URB.
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Ko, Man-yan Fanny, and 高文欣. "A review of the indicators used for monitoring beach water quality in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31254573.
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Glas, Bo. "Methodological aspects of unspecific building related symptoms research." Doctoral thesis, Umeå : Institutionen för folkhälsa och klinisk medicin, Umeå universitet, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-30640.
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Blackburn, Lynda G. "Quantification and estimation of nitrous oxide emissions from dairy manure applications in a western Quebec pea-forage and an eastern Ontario alfalfa-forage cropping system : by Lynda G. Blackburn." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100771.
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Agricultural systems are known to emit nitrous oxide (N2O)---a potent greenhouse gas. The roving flux tower measuring system of Agriculture and Agri-Food Canada was used to make continuous measurements of N2O fluxes in an edible pea field in Western Quebec in 2003-04 and then in an alfalfa-timothy forage field in Eastern Ontario in 2004-05. The experiment was designed to capture, at the field scale, the expected large N2O emissions occurring as a result of fertilizer application for a year, in relation to both large precipitation events and spring thaw.Growing season N2O emissions averaged 0.5 to 5 mg N2 O-N m-2 d-1 with peaks following snow melt (between 5 and 8 mg N2O-N m-2 d-1) and manure applications (8 to 37 mg N2O-N m-2 d -1). Although generally small (<0.25 mg N2O-N m -2 d-1), emissions were detectable during the fall and winter, indicating the importance of including them in annual emission totals.
The measurements were used to verify the performance of the simulation model DNDC (DeNitrification-DeComposition) in estimating N2O emissions from legumes and in response to dairy manure application. Sensitivity tests were also carried out in which baseline input values were modified. Results suggest that the current model version (DNDC8.9) requires further modification prior to application for estimating greenhouse gas emissions in national accounting systems.
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Lin, Pingying, and 林萍英. "Influence of urban design factors on summertime urban heat island intensity : on-site measurement of pocket parks in high-rise high-density environment in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/211106.
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n, Hussin Wan Mohd Rauhan. "Measurement of changes in marine benthic ecosystem function following physical disturbance by dredging." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/2838.
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Measuring the impact of physical disturbance on macrofaunal communities and sediment composition is important given the increased demand for the exploitation and disturbance of marine ecosystems. The aim of the present investigation was to provide a comprehensive study about the extent to which the disturbance (especially aggregate dredging) may affect benthic ecosystem function. The first part of the thesis concerns a field investigation of the impacts of dredging on the benthic community and related ecosystem function which was measured by different approaches including traditional methods based on benthic community structure and a more novel approach based on the functional traits of benthic organisms. The assessment was done by comparing dredged sites (Area 222, southeast England) with nearby undisturbed reference sites from the years 2001 to 2004 and in 2007. In general, low dredging intensity did not appear to impose great impacts on the benthic community and related ecosystem function compared to the higher intensity activity. Most of the analyses suggested that the community at the high dredging intensity site had yet to recover at the end of this study period. Among many factors related to the recovery of the benthic community was sediment composition where gravel deposits appeared to support a faster biological recovery. Meanwhile, the recovery of species with specific traits, such as tube-building and filter feeding also indicate a faster recovery for the whole community. The experimental work to determine different impacts of Hediste diversicolor on its surrounding depending on its relative size is discussed in Appendix 1.
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Greenwood, M. F. D. "The fish populations of the Lower Forth Estuary, including the environmental impact of cooling water extraction." Thesis, University of Stirling, 2001. http://hdl.handle.net/1893/22856.
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The present study investigated the fish populations of the lower Forth Estuary, east Scotland. Cooling water extraction by the 2400 MW Longannet Power Station (LPS) inevitably removes a certain quantity of fish from the estuary, all of which experience mortality. The present study employed a sampling regime of greater intensity than previous studies to investigate the extent of mortalities from January 1999 - December 2000. Collections of fish impinged on intake screens were made eight times monthly, at LW or HW of spring or neap tides during the day or by night. Marine species dominated the assemblage of fish collected, with sprat, herring, and whiting contributing > 80% of total abundance. Sprat was twice as abundant as herring in 1999, while the proportions were very similar in 2000. Total abundance of all species collected in 1999 was estimated at 1. 09 x 107, while the value of 3.29 x 107 in 2000 was three times larger. These figures were the largest recorded among British estuarine and marine power stations, but were precisely the correct order based on an exponential relationship between total impingement and water abstraction rate established from data from other locations. Validation of the estimated total biomass of fish removed was given by comparison with the known total mass of all materials disposed to landfill. Statistical analysis of impingement data showed that tidal range and season were the most important environmental variables influencing the rate of removal of fish from the estuary. That light was not significant for most species is attributed to high levels of turbidity and the resulting low visibility by day and night. Demersal and benthic fish abundances collected from 1982 - 2000 in 30 annual trawls at three sites in the mid-lower Forth Estuary were analysed. Species tended to be present in greatest abundance at the most seaward of the sites. Patterns of seasonal abundance reflected those observed in the impingement study at LPS, and catches tended to be greatest at L W. Total species richness showed no significant trend over time, whilst total annual abundance of fish captured in trawls showed a significant negative trend. This was largely due to significant declines in the two most abundant species, namely whiting and eel pout, attributable in the latter case to increasing temperatures. Changes in the ichthyofaunal composition were largely driven by whiting, eel pout, cod and plaice. Eight of ten common species showed no significant trend in abundance over the length of the time series, suggesting them to perhaps be at equilibrium densities. Quantities of commercially fished species above minimum landing size limits that were removed by LPS were very low, and restricted to herring and occasional whiting. The quantity of juveniles that could have recruited into the fished populations was expressed as equivalent adults. The values were larger than any previously reported in the UK, primarily due to the quantities of juvenile fish impinged being greater than at any other British power station, and the importance of the Forth as a nursery area for marine species. It was concluded that LPS is the dominant UK power station in terms of magnitude of impingement losses. It may be prudent to consider a precautionary approach to mitigate losses, and to this end options for reduction of the magnitude of impingement are discussed.
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Li, Weiping. "A subsurface water quality evaluation system for assessing NPS pollution potential by pesticides." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40028.
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A watershed scale water quality evaluation system was developed for assessing spatial variation of subsurface pesticide movement. The system consists of a linked-transport model component for performing simulation and a GIS component for processing spatially-related data. The surface heterogeneity caused by agricultural activities, topographic, hydrologic, and soil type variations in a watershed was handled by partitioning the watershed into homogeneous subfields. The subsurface soil profile and aquifer heterogeneities were considered by dividing the subsurface domain into root zone, intermediate vadose zone, and saturated zone, respectively. On each of the homogeneous subfields, the physically-based models, PRZM and VADOFT, were linked to simulate pesticide transport in the root and intermediated vadose zones. Pesticide movement in groundwater underneath the watershed was simulated by linking the other two models with SUTRA. An irregular shape finite element mesh generator was developed for fitting the irregular shape watershed boundary and reducing the number of nodes of the finite element mesh. Either transient or steady state flow and transport simulation could be performed with the system. The system is able quantitatively to produce detailed spatial variation maps of pesticide concentrations at any desired depth in the unsaturated zone and in groundwater.
The system requires spatially-distributed information as inputs. Management of large volumes of spatially-referenced data which represent the heterogeneous properties of the watershed were facilitated by a developed GIS component. The GIS data processing component was composed of spatial data manipulation and display, attribute database management, and model input information extraction subcomponents. The spatial data processing component consists of data format conversion, map registering, map editing, new information generation, and map display subcomponents.Ph. D.
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Deng, Wen Jing. "Characterization and cytotoxicity of POPs and heavy metals in TSP and PM2.5 from an electronic waste recycling site, compared with five urban sites in SE China." HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/812.
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Kutschera, Ellynne Marie. "Mechanisms of Methane Transport Through Trees." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/643.
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Although the dynamics of methane (CH4) emission from croplands and wetlands have been fairly well investigated, the contribution of trees to global methane emission and the mechanisms of tree transport are relatively unknown. Methane emissions from the common wetland tree species Populus trichocarpa (black cottonwood) native to the Pacific Northwest were measured under hydroponic conditions in order to separate plant transport mechanisms from the influence of soil processes. Roots were exposed to methane enriched water and canopy emissions of methane were measured using a canopy enclosure. Methane accumulation in the canopy was generally linear and the average canopy methane flux was 3.0 ± 2.6 μg CH4 min-1. Flux magnitudes from stem experiments scaled to the area of the main tree stem are comparable to whole-canopy flux values, indicating that the majority of methane emitted from the tree leaves through the stem. Samples for stable carbon isotope composition were taken during the canopy experiments. Compared to the isotopic composition of root water methane, canopy methane was depleted in 13C on average by 8.6 ± 3.3 permil; this indicates that methane moving through the tree is not following a purely bulk flow pathway (where no depletion would occur), but is instead subject to at least one fractionating mechanism. When temperature was varied, the flux at the coolest temperature was significantly different from the higher flux at the warmest temperature (p-value less than 0.02). The calculated Q10 for methane flux was 2.4, which indicates a positive feedback with temperature increase. Analysis of δ13C values of emitted CH4 in the temperature experiments shows increasing depletion with cooler temperatures and lower flux. This indicates that not only does the magnitude of flux vary with temperature, but the actual dominant transport mechanism changes as well.
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Guiseppe, Vincente E. "Radon in Ground Water: A Study of the Measurement and Release of Waterborne Radon and Modeling of Radon Variation in Bedrock Wells." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/GuiseppeVE2006.pdf.
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Bell, Katherine Eleanor. "Identification and Characterization of Fine Particulate Matter Hot Spots on an Urban Arterial Corridor Integrating Probe Vehicle, Traffic and Land Use Data." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1535.
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The purpose of this study is to explore the use of integrated probe vehicle, traffic and land use data to identify and characterize fine particulate matter (PM[subscript 2.5]) hot spot locations on urban arterial corridors. In addition, a preliminary analysis is conducted to consider volatile organic compound (VOC) hot spot locations. A pollutant hot spot is defined as a location on a corridor in which the mean pollutant concentrations are consistently above the 85th percentile of pollutant concentrations when compared to all locations along the corridor. In order to collect data for this study, an electric vehicle was equipped with instruments designed to measure PM[subscript 2.5] and total VOC (TVOC) concentrations. Second-by-second measurements were performed for each pollutant from both the right and left sides of the vehicle. Detailed meteorological, traffic and land use data is also available for this research. The results of a statistical analysis, including multiple regression, are used to better understand which data sources are most valuable in estimating PM[subscript 2.5] hot spot locations consistent with empirical data; knowledge is gained as to which variables have the strongest statistical relationships with traffic emissions and pollutant levels at a corridor level. A preliminary analysis is also completed to consider which variables are statistically related to TVOC hot spot locations. This research highlights the importance of considering both consistency and magnitude of pollutant concentrations when identifying hot spot locations. An objective of this research is to develop a method to identify urban arterial hot spot locations that provides a balance of efficiency (in terms of capital expenses, time, resources, expertise requirements, etc.) and accuracy.
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Roskamp, Melissa Jordan. "Characterization of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography with Time of Flight Mass Spectrometry (GC×GC/TOFMS)." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1411.
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The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better characterizing biogenic VOCs (BVOCs) and thus SOA precursors.
This work presents measurements of BVOCs collected during two field campaigns and analyzed using GC×GC/TOFMS. The first campaign, the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS), took place in a Ponderosa pine forest in Colorado. The second campaign, Particle Investigations at a Northern Ozarks Tower: NOx, Oxidant, Isoprene Research (PINOT NOIR) Study, was conducted in the Ozark region of Missouri. Tens to hundreds of BVOCs were quantified in each set of samples, including primary emissions, atmospheric oxidation products, stress indicators and semi-volatile leaf surface compounds. These findings highlight that there is a largely uncharacterized diversity of BVOCs in ambient samples. Our findings demonstrate that GC×GC can distinguish between compounds with the same molecular weight and similar structures, which have highly variable potentials for production of SOA (Lee et al., 2006). This work represents some of the first analysis of ambient BVOCs with this technology, which is anticipated to contribute greatly to characterization of atmospheric SOA precursors and ultimately, regional and global modeling of SOA and fine particulate matter.
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Ho, Ching-yee Christina, and 何靜宜. "The biomonitoring of heavy metal pollution in the wood and leaf chemistry of urban trees in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B43893958.
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Cheung, Wai-fun, and 張慧芬. "Identifying Hong Kong traffic composition and vehicle outputs for use in road noise modelling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31253994.
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Ma, Kit-cheong James, and 馬傑昌. "Hong Kong Government criteria for assessing contamination levels of dredged marine sediments." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31254718.
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Mdaka, Themba Cyprian. "Assessment of noise levels in work areas at the Polokwane Platinum Smelter, South Africa." Thesis, University of Limpopo, 2015. http://hdl.handle.net/10386/1296.
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Thesis (M.Sc (Physiology)) --University of Limpopo, 2015Objective This study assesses whether noise levels above legal limits of 85 dB(A) that can result in noise-induced hearing loss are present in areas where employees are supposed to work and to verify that such areas are demarcated as noise zones at the Polokwane Platinum Smelter. Background and motivation Excessive noise is a global health hazard with considerable social and physiological impact, including the development of noise-induced hearing loss (NIHL). Noise is a major hazard in many workplaces. It is estimated that more than 30 million workers (almost 1 in 10) are exposed to unsafe noise in their work places. NIHL is the second most self-reported occupational illness or injury in the United States. Amongst miners, more than 90% of the population reports hearing problems by the age of 55 years. Noise exposure is prevalent in construction, foundries, agriculture, transport, industry and mining-related activities. The prevalence of NIHL has not changed much in the past two decades. Therefore, a hearing conservation programme is an important issue in the smelter as certain areas are denoted as noise areas. Study design A cross-sectional study design with a group of utility workers at the Polokwane Platinum Smelter, as the experimental group, and a group of undergraduate Bachelor of Science students at the University of Limpopo (Turfloop Campus) served as a control group. Method A sound level meter was used to measure the noise levels where the utility group performs their technical work. Data were analysed using the Statistical Package for the Social Sciences (SPSS) computer program. Results The average noise measured in various locations of the Polokwane Platinum Smelter was between 62.6 dB(A) and 105.1 dB(A). The results indicated that workers at the Polokwane Platinum Smelter are over exposed to noise in certain work areas if they work eight hours in the area. Areas where the average noise level was above noise rating limit of 85 dB(A) were demarcated as noise zones as an additional protective measure. Employees also use hearing protective devices, when they are working in noise zones, to control personal noise exposure. This is in accordance with the Occupational Health and Safety Act No. 85 of 1993 as amended eleventh edition (OHS Act 85/93). Conclusion In the present study, noise levels in certain areas exceeded the noise rating limit of 85 dB(A). However such areas are clearly demarcated as noise areas and employees accessing those area must wear earmuffs or earplugs. Possibilities of employees developing hearing loss overtime exist, if employees work for eight hours or longer in demarcated areas and do not adhere to the existing Hearing Conservation Program (HCP) implemented at the Polokwane Platinum Smelter. Noise levels at the Polokwane Platinum Smelter should be monitored regularly.
University of Limpopo
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Mensah, Paul Kojo. "Environmental water quality management of glyphosate-based herbicides in South Africa." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001987.
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Although the use of pesticides is necessary to meet the socio-economic needs of many developing countries, especially in Africa, side effects of these bio-active chemicals have contributed to contaminating aquatic and terrestrial ecosystems. Environmental water quality degradation by pesticides interferes with ecosystem health and poses numerous risks to aquatic life. In South Africa, glyphosate-based herbicides are frequently used to control weeds and invading alien plants, but ultimately end up in freshwater ecosystems. However, there are no South African-based environmental water quality management strategies to regulate these bio-active chemicals. Therefore, this study sought to provide a sound scientific background for the environmental water quality management of glyphosate-based herbicides in South Africa, by conducting both laboratory and field investigations. In the laboratory investigations, aquatic ecotoxicological methods were used to evaluate responses of the freshwater aquatic shrimp Caridina nilotica exposed to Roundup® at different biological system scales, and the responses of multiple South African aquatic species exposed to Roundup® through species sensitivity distribution (SSD). In the field investigations, the effect of Kilo Max WSG on the physicochemical and biological conditions of three selected sites in the Swartkops River before and after a spray episode by Working for Water were evaluated through biomonitoring, using the South African Scoring System version 5 (SASS5) as a sampling protocol. Both Roundup® and Kilo Max WSG are glyphosate-based herbicides. All the data were subjected to relevant statistical analyses. Findings of this study revealed that Roundup® elicited responses at different biological system scales in C. nilotica, while SSD estimates were used to derive proposed water quality guidelines for glyphosate-based herbicides in South Africa. The biomonitoring revealed that using glyphosate-based herbicides to control water hyacinth within the Swartkops River had a negligible impact on the physicochemical and biological conditions. Based on these findings, a conceptual framework that can be used for the integrated environmental water quality management of glyphosate-based herbicides in South Africa was developed as part of integrated water resource management (IWRM). The combined data sets contribute to a sound scientific basis for the environmental water quality management of glyphosate-based herbicides in South Africa.
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Crewe, Julie R. "Analysis of Mercury Concentrations in Indiana Soil to Evaluate Patterns of Long-Term Atmospheric Mercury Deposition." Thesis, 2013. http://hdl.handle.net/1805/3199.
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Indiana University-Purdue University Indianapolis (IUPUI)Mercury (Hg) has proven to be a risk to the public, mainly through the consumption of fish. Because of this, many fish consumption advisories have been issued in Indiana. Although much is known about the global cycle of mercury, little is known about how local and regional emission sources of mercury impact local and regional mercury cycling. This study’s objective was to determine the scope of mercury concentration in central Indiana by using a broad grid of soil mercury measurements. Sampling was designed to capture the net retained mercury content in soils, and to determine whether spatial patterns in exist in soil mercury contents that could be related to emission sources of mercury and post-emission transport patterns from wind. Results from this study revealed significant differences in mercury concentrations for soils in central Indiana. The core of the study area, concentrated in the urban area of Indianapolis, exhibited soil mercury contents that were 20 times higher than values in the outskirts of the study area. The spatial pattern resembled a bulls-eye shape centered on Indianapolis, and with comparison to the reported Hg emission from local sources, including a coal-fired power plant, indicates a strong regional deposition signal linked to those emission sources but marked by wind-driven transport to the northeast. This effect of local emission sources resulting in local deposition indicates that limiting mercury emissions will have a net beneficial impact on local environmental quality and human health.
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Smyth, Jeffrey D. "Multivariate geostatistical analysis of groundwater contamination by pesticide and nitrate." Thesis, 1988. http://hdl.handle.net/1957/26873.
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A field study was conducted to determine the applicability of multivariate
geostatistical methods to the problem of estimating and simulating pesticide
concentrations in groundwater from measured concentrations of nitrate and pesticide,
when pesticide is undersampled. Prior to this study, no published attempt had been made
to apply multivariate geostatistics to groundwater contamination.
The study was divided into two complementary aspects of geostatistics: estimation
and simulation. The use of kriging and cokriging to estimate nitrate and the herbicide
dimethyl tetrachloroterepthalate (DCPA) contaminant densities is described in Chapter I.
Measured concentrations of nitrate and the DCPA were obtained for 42 wells in a shallow
unconfined alluvial and basin-fill aquifer in a 16.5 km² agricultural area in eastern
Oregon. The correlation coefficient between log(nitrate) and log(DCPA) was 0.74.
Isotropic, spherical models were fitted to experimental direct- and cross-semivariograms
with correlation ranges and sliding neighborhoods of 4 km. The relative gain for
estimates obtained by cokriging ranged from 14 to 34%. Additional sample locations
were selected for nitrate and DCPA using the fictitious point method. A simple economic
analysis demonstrated that additional nitrate samples would be more beneficial in reducing
estimation variances than additional DCPA samples, unless the costs of nitrate and DCPA
analysis were identical.
These estimates are by definition, the Best Linear Unbiased Estimates (i.e., the
estimates with minimized estimation variance), however the requirement of minimized
variance smoothes the variability of contaminant values. The application of conditional
simulations to groundwater contamination is described in Chapter 11. Conditional
simulation allows the degree of fluctuation of nitrate and DCPA between sample points to
be assesed. With knowledge of both the 'best' estimates and the of the variability
between sample points, nitrate and DCPA groundwater contamination in the study area
can be characterized
Based on the semivariogram models found in Chapter I, univariate and
multivariate conditional simulations of nitrate and DCPA were generated using the turning
bands method and the kriging or cokriging system. Kriging was used to condition the
univariate simulations, while cokriging was used to cross-correlate and condition the
multivariate simulations. The mean of 25 conditional and coconditional simulations at 8
different locations in the study area were generated and compared to kriging and
cokriging estimates and 95% confidence intervals.
Both conditional and coconditional simulation of the DCPA and nitrate
contaminant densities showed large variations when values in different simulations were
compared. The fluctuation in values demonstrate the uncertainties in the contaminant
distributions when sample sizes are small. As a result of this unkown component,
simulated values vary widely. Coconditional simulation displayed the cross-correlation
imposed by using the cokriging system to condition the simulations. After 25
simulations, the mean remained unstable indicating that more simulations would be
required to enable comparisons with kriging and cokriging estimates.Graduation date: 1989