Tesi: "Nitrogen oxides Environmental aspects"

1

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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2

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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3

Crawford, Ian Stewart. "Catalytic reduction of nitric oxide by carbon monoxide or hydrogen over a Monel metal catalyst". Title page, contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09EN/09enc899.pdf.

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4

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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5

Lim, Guo Quan. "Evaluation of the Influence of Non-Conventional Sources of Emissions on Ambient Air Pollutant Concentrations in North Texas". Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804841/.

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Emissions of air pollutants from non-conventional sources have been on the rise in the North Texas area over the past decade. These include primary pollutants such as volatile organic compound (VOC) and oxides of nitrogen (NOx) which also act as precursors in the formation of ozone. Most of these have been attributed to a significant increase in oil and gas production activities since 2000 within the Barnett Shale region adjacent to the Dallas-Fort Worth metroplex region. In this study, air quality concentrations measured at the Denton Airport and Dallas Hinton monitoring sites operated by the Texas Commission on Environmental Quality (TCEQ) were evaluated. VOC concentration data from canister-based sampling along with continuous measurement of oxides of nitrogen (NOx), ozone (O3), particulate matter (PM2.5), and meteorological conditions at these two sites spanning from 2000 through 2014 were employed in this study. The Dallas site is located within the urban core of one of the fastest growing cities in the United States, while the Denton site is an exurban site with rural characteristics to it. The Denton Airport site was influenced by natural gas pads surrounding it while there are very few natural gas production facilities within close proximity to the Dallas Hinton site. As of 2013, there were 1362 gas pads within a 10 mile radius to the Denton Airport site but there were only 2 within a 10 mile radius to Dallas Hinton site. The Dallas site displayed higher concentrations of NOx and much lower concentrations of VOC than the Denton site. Extremely high levels of VOC measured at the Denton site corresponded with the increase in oil and gas production activities in close proximity to the monitoring site. Ethane and propane are two major contributors to the measured VOC concentration, suggesting the influence of fugitive emissions of natural gas. In Dallas, the mean and maximum values of ozone had decreased since 2000 by about 2% and 25%, respectively. Similarly NOx decreased by 50% and 18% in the mean and maximum values. However, the mean VOC value showed a 21% decrease while the maximum value increased by about 46%. In Denton, the change in percentage of ozone and NOx were similar to Dallas but the mean VOC concentration increased by about 620% while the max value increased 1960%. Source apportionment analysis confirmed the findings by identifying the production of natural gas to be the primary source of VOC emissions in Denton, while traffic sources were more influential near the Dallas site. In light of the recent proposal by EPA to revise the ozone standard, the influence of these new unconventional sources should be further evaluated.

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6

Shihady, Steven. "TREATMENT OF NITROGEN OXIDES BY CHLORELLA VULGARIS ALGAE IN PHOTOBIOREACTORS". DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1284.

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The effectiveness of algae to treat NO2and NO in simulated flue gas was tested using Chlorella vulgaris in photobioreactors (PBRs) using NOxconcentrations between 30 ppm to 780 ppm. NOxdissolved and reacted in water to form NO3-and NO2-in the PBR growth medium, providing a nitrogen source that the algae readily assimilated for cell synthesis. Three 20-L photobioreactors were inoculated with a pure culture of C. vulgaris prepared in Bristol growth medium and algae were grown in the PBRs at 25°C and pH of 7.0 in a modified Bristol medium that did not contain nitrogen compounds. The C. vulgaris grew substantially using NO3-/NO2-as its nitrogen source for cell synthesis. The NO3-and NO2-were formed through the dissolution and oxidation/reduction of NOxfrom the simulated flue gas. Algal growth by assimilation of NO3-and/or NO2-allowed for continual dissolution of NOx, resulting in NOxremoval rates from the gas phase of up to 97%, with residual nitrogen of up to 7 mg-N/L in solution. Algae grew from an initial cell density of 3.1 x 105cells/L to cell densities of up to 1.85 x 107cells/mL and dry weights of up to 243 mg/L. Cell nitrogen content varied from 4-8%. PBR to treatment of gaseous NOxwas analyzed in terms of mass transfer rates, chemical kinetics, and biological growth.

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7

Walecka-Hutchison, Claudia. "Nitrogen dynamics in diesel biodegradation : effects of water potential, soil C:N ratios, and nitrogen cycling on biodegradation efficacy". Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/191274.

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Respirometric experiments were performed to evaluate the role of nitrogen in aerobic diesel biodegradation. Specific objectives included 1) evaluating the effects of water potential induced by various nitrogen amendments on diesel biodegradation rates in arid region soils, 2) comparing concurrent effects of C:N ratios and soil water potential on diesel degradation rates, and 3), measuring gross rates of nitrogen cycling processes in diesel-contaminated soil to determine duration of fertilizer bioavailability. In all studies, increasing nitrogen fertilization resulted in a decrease in total water potential and correlated with an increase in lag phase and overall reduction in microbial respiration. Highest respiration and estimated diesel degradation was observed in the 250 mg N/kg soil treatments regardless of diesel concentration, nitrogen source, or soil used, suggesting an inhibitory osmotic effect from higher rates of nitrogen application. The depression of water potential resulting in a 50% reduction in respiration was much greater than that observed in humid region soil, suggesting higher salt tolerance by microbial populations of arid region soils. Due to the dependence on contaminant concentrations, use of C:N ratios was problematic in optimizing nitrogen augmentation, leading to over-fertilization in highly contaminated soils. Optimal C:N levels among those tested were 17:1, 34:1, and 68:1 for 5,000, 10,000 and 20,000 mg/kg diesel treatments respectively. Determining nitrogen augmentation on the basis of soil pore water nitrogen (mg N/kg soil H₂0) is independent of hydrocarbon concentration but takes into account soil moisture content. In the soil studied, optimal nitrogen fertilization was observed at an average soil pore water nitrogen level of 1950 mg N/kg H₂0 at all levels of diesel contamination. Based on the nitrogen transformation rates estimated, the duration of fertilizer contribution to the inorganic nitrogen pool at 5,000 mg/kg diesel was estimated at 0.9, 1.9, and 3.2 years in the 250, 500, and 1000 mg/kg nitrogen treatments respectively. The estimation was conservative as ammonium fixation, gross nitrogen immobilization, and nitrification were assumed as losses of fertilizer with only gross mineralization of native organic nitrogen contributing to the most active portion of the nitrogen pool.

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8

Samoylov, Alexander V. "Improvement of the efficiency of vehicle inspection and maintenance programs through incorporation of vehicle remote sensing data and vehicle characteristics". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50410.

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Emissions from light-duty passenger vehicles represent a significant portion of total criteria pollutant emissions in the United States. Since the 1970s, emissions testing of these vehicles has been required in many major metropolitan areas, including Atlanta, GA, that were designated to be in non-attainment for one or more of the National Ambient Air Quality Standards. While emissions inspections have successfully reduced emissions by identifying and repairing high emitting vehicles, they have been increasingly inefficient as emissions control systems have become more durable and fewer vehicles are in need of repair. Currently, only about 9% of Atlanta area vehicles fail emissions inspection, but every vehicle is inspected annually. This research addresses explores ways to create a more efficient emissions testing program while continuing to use existing testing infrastructure. To achieve this objective, on road vehicle emissions data were collected as a part of the Continuous Atlanta Fleet Evaluation program sponsored the Georgia Department of Natural Resources. These remote sensing data were combined with in-program vehicle inspection data from the Atlanta Vehicle Inspection and Maintenance (I/M) program to establish the degree to which on road vehicle remote sensing could be used to enhance program efficiency. Based on this analysis, a multi-parameter model was developed to predict the probability of a particular vehicle failing an emissions inspection. The parameters found to influence the probability of failure include: vehicle characteristics, ownership history, vehicle usage, previous emission test results, and remote sensing emissions readings. This model was the foundation for a proposed emissions testing program that would create variable timing for vehicle retesting with high and low failure probability vehicles being more and less frequently, respectively, than the current annual cycle. Implementation of this program is estimated to reduce fleet emissions of 17% for carbon monoxide, 11% for hydrocarbons, and 5% for nitrogen oxides in Atlanta. These reductions would be achieved very cost-effectively at an estimated marginal cost of $149, $7,576 and $2,436 per-ton-per-year for carbon monoxide, hydrocarbons, and nitrogen oxides emissions reductions respectfully.

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9

Cochlan, William Patrick. "Nitrogen uptake by marine phytoplankton : the effects of irradiance, nitrogen supply and diel periodicity". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30628.

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Diel patterns of nitrogen (NO₃⁻, NH₄⁺, urea) uptake were investigated in natural assemblages of phytoplankton from neritic and oceanic environments off the coast of British Columbia. This is the first study to report nitrogen uptake rates and extensive measurements of ambient NH₄⁺ and urea concentrations in these waters. Calculated rates of N uptake, 15 based on ¹⁵N incorporation into particulate matter during time course experiments, were maximal during the day and minimal at night. Besides the obvious effects of irradiance, the amplitude of the periodicity in uptake rate was influenced by phytoplankton community composition, ambient nitrogen concentration, forms of nitrogen available, and depth of sampling. Uptake of nitrogen during the night and in artificial darkness were measurable proportions of daytime and light uptake rates, with the importance of dark uptake generally increasing with increasing N limitation. This is the first study of diel urea uptake by marine phytoplankton in the field. The ratios of dark to light urea uptake over a diel cycle were more similar to those of NO₃⁻than those of the other reduced N form, NH₄⁺. Rates of NO₆⁻ and urea uptake by phytoplankton in the shallow and deep chlorophyll layers of the Strait of Georgia were measured over a gradient of irradiances and results of these experiments could be fitted with a hyperbolic function similar to the Michaelis-Menten equation. Half-saturation constants (KLT) for light-dependent uptake of urea and NO₃⁻ ranged from 0 to 14% of the surface irradiance and dark uptake was a variable, but often substantial (> 50%) portion of the total (light + dark) uptake. The uptake response of nitrate-replete and -starved populations of the picoflagellate, Micromonas pusilla (Butch.) Manton et Parke, to urea, NH₄⁺ and NO₃⁻ perturbations was determined by both ¹⁵N accumulation and nutrient disappearance from the culture medium. Maximum specific uptake rates (Vmax) of NH₄⁺ were 0.13 h⁻¹, more than 2 times the Vmax of NO₃⁻ or urea (ca. 0.05 h⁻¹). The half-saturation constants (Ks) for urea, NH₄⁺ and NO₃⁻ were within ± 0.1 µg-at N•L⁻¹ of each other; the average value of 0.41 µg-at. N•L⁻¹ is within the range reported for small, oceanic diatoms. NO₃⁻ uptake was completely inhibited following NH₄⁺ addition (1-10 µg-at. N•L⁻¹), whereas urea addition resulted in only a 28% reduction in NO3- uptake. Starved cultures of M. pusilla exhibited variable uptake of NH₄⁺ and urea as a function of time, with an initial "surge" uptake response. This is the first laboratory study of N uptake by an eucaroyotic picoplankter and demonstrates that many of the transient uptake responses reported for diatoms, with which it competes in the field, are common to this picoplankter. Diel periodicity of nitrogen uptake and assimilation were measured in N-replete batch cultures of M. pusilla and also in N-limited cyclostat cultures (14L:10D) at three growth rates corresponding to ca. 75, 50 and 25% of it's maximal growth rate. Nitrate uptake was continuous and independent of the L:D cycle in the cyclostat cultures at the lowest dilution rate, but NO₃⁻ uptake rates exhibited pronounced periodicity in the batch and higher dilution rate cultures, a response similar to that seen in previous studies of cyclostat cultures of some diatoms. Diel patterns in cell division, mean cell volume, potential uptake rates and internal pools of NO₃⁻ were also observed and are discussed with respect to the nutritional status of the cells. The effect of irradiance on the uptake of NH₄⁺ and NO₃⁻ by M. pusilla was also described by Michaelis-Menten kinetics; with increasing N limitation the importance of light for nitrogen uptake decreased and dark uptake increased from 5-20% to 21-39% of NO₃⁻ and NH₄⁺ uptake rates, respectively, at saturating irradiance.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

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10

Hengnirun, Somgiat. "A computer simulation model for manurial nitrogen management : environmental aspects (MANIMEA)". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40357.

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The MANIMEA $ rm ( underline{MA}nurial underline{NI}trogen underline{M}anagement{:} underline{E}nvironmental underline{A}spects)$ model is a one-dimensional dynamic model that simultaneously simulates nitrogen transformations (volatilization, net mineralization-immobilization, and denitrification), nitrogen transport (runoff and leaching), plant uptake, and adsorption in homogeneous, unsaturated soils. The simulated system is divided into two components: the applied manure layer and the soil. The model describes the transformation processes occurring in both components separately. It is also capable of accounting for both micro and macroporous flows. In addition, the simulation can be done for time steps shorter than 1 day.
The model was developed to be interactive and user-friendly and was constructed on a modular basis using Microsoft FORTRAN PowerStation$ sp circler$ as a compiler. It can be run on an IBM$ sp circler$ or IBM compatible microcomputer with a minimum requirement of a 386 microprocessor with 4 MB RAM. This model was developed as a nitrogen management-oriented model. However, it can also be used to gain further understanding of nitrogen processes for research and teaching purposes.
The accuracy of the stimulation was enhanced by taking into account moisture and temperature variation and distribution in the soil. The SWACROP and the HEAT programs were integrated into the MANIMEA model to generate transient moisture and temperature profiles, respectively. The Numerical Method Of Lines (NMOL) technique, which implements finite difference method, was used to numerically solve the partial differential equations in the model.
Generally, the results generated by the MANIMEA model using the parameters from literature agreed with the results obtained by analytical solutions and from experiments. It was found that the model is highly sensitive to the volatilization and net mineralization rate constants $(K sb{v}$ and $K sb{m}).$ The study showed that the MANIMEA model can be implemented to evaluate nitrogen transformations, transport, and plant uptake for a wide range of climatic and soil conditions and organic type of wastes. Such a tool can contribute to the protection of our environment through a better management of organic nitrogen fertilizer and a better understanding of the nitrogen processes.

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11

Bose, Arun Chand. "Pulverized coal combustion: Fuel nitrogen mechanisms in the rich post-flame". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184635.

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Chemical kinetic mechanisms governing the fate of coal nitrogen in the fuel-rich stage of a pulverized-coal staged combustion process were investigated. Emphasis was on determination of the effects of coal rank, temperature and stoichiometric ratios on the speciation and rates of destruction of nitrogenous species and correlation of coal data by a unif1ed mechanism. The relative importance of homogeneous and heterogeneous mechanisms during post-flame interconversion reactions of the fuel nitrogen pool was quantified. Experiments with doped propane gas and a high- and low-grade coals, burned under a variety of conditions in a 2 Kg/h downflow combustor, yielded timeresolved profiles of temperature, major (H₂, CO, CO₂, O₂ and N₂), nitrogenous (NO, HeN and NH₃) and hydrocarbon (CH₄ and C₂H₂) species. These profiles allowed global mechanisms describing the speciation and destruction of fuel nitrogen species to be explored, using predictive models of increasing levels of sophistication. Fuel nitrogen speciation varied significantly from coal to coal and depended on stoichiometric ratio and temperature, which were varied independently. A general correlation describing the destruction rate of NO was derived from data. This rate, which was first-order in both NO and NH₃, was generally valid for all coals and all conditions examined. Fuel nitrogen interconversion reactions, especially destruction of NO and HeN, was predominantly homogeneous, but no single elementary reaction was controlling. Temperature quench down the combustor is the origin of OH equilibrium overshoot. Expressions for estimating the OH equilibrium overshoot as a function of the axial temperature decay along the combustor were derived both empirically and kinetically from fundamental considerations using data from doped propane gas runs. These expressions, together with available literature values of gas phase rate coefficients, could adequately describe the post-flame NO and HeN profiles of coal and gas runs. HeN profiles in the far postflame zone of the coal flames are strongly influenced by the slow release of nitrogen from the coal residue. This devolatilization plays a critical role in supplying the HeN that drives the multistep process converting fuel N into molecular nitrogen.

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12

Anand, Archana. "The nitrogen isotope fingerprint of wastewater effluents in Hong Kong". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/207619.

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Nitrogen pollution in marine waters is directly tied to human development – including agricultural runoff, atmospheric deposition, and urban wastewater effluents. After more than a century of urbanization, Hong Kong faces a major challenge in mitigating marine pollution, particularly nitrogen. Indeed, nitrogen pollution may be one of the primary causes of benthic ecosystem decline as evidenced by a contraction in the historical distribution of corals and seagrasses. Such ecosystems provide vital ecosystem services, not limited to nursery grounds for economically important fisheries. While the Hong Kong Government (HK Environmental Protection Department) has established long-term monitoring of marine nitrogen concentrations, the data obtained on the size of the total nitrogen pool does not indicate the proportion of which is derived from human activities. Stable isotope analysis of nitrogen (δ15N) can provide more accurate information on the source of nitrogen not only in the receiving environment but also in the marine and benthic organisms present. This project critically examines Hong Kong’s nitrogen sources from sewage effluents using stable isotope analysis. Objectives were to investigate (1) the δ15N of sewage effluents sampled across Hong Kong, Kowloon, New Territories, Lantau and Outlying Islands (2) the differences in δ15N across sewage treatment type and (3) the differences in δ15N between the wet and dry seasons with the aim of developing a new approach for detecting and mapping sewage impacts in Hong Kong. Through a 6-month sampling effort across 18 sewage treatment facilities, this study shows that 70% of δ15N values obtained from the sewage effluents were characteristically enriched (δ15N values up to 205 ‰) when compared with naturally occurring nitrogen sources in the biosphere (I10‰ < δ15N < 10‰). Overall, δ15N was more variable in plants with preliminary treatment and chemically enhanced primary treatment (CEPT) than in plants with primary, secondary or tertiary treatment. The mean daily flow rate explained 75.7% of the observed variability in δ15N values of preliminary treatment plants and 85% of the variability in primary treatment plants. This was also the case in plants having CEPT with a negative correlation of 46% between mean daily flow rate and sewage effluent δ15N values. This suggests varying models for the quantity and retention time of wastewater versus δ15N signatures for different treatment types that require further study. Microbial activity by aerobic bacteria and protozoa, ammonia volatilization and the amount of nitrogen present in the effluents are possible causes for δ15N enrichment. Enterococcus counts of three sites sampled indicated that that the municipal sewer system and wastewater treatment plant in Stonecutters Island (56,100 CFU 100 mlI1) and preliminary treatment facilities (57,800 CFU 100 mlI1) in Hong Kong Island are insufficient in preventing bacterial contamination in comparison to US EPA standards for recreational use of coastal marine waters (35 CFU 100 mlI1). These findings indicate that enriched δ15N values directly translate to the presence of anthropogenic inputs and that monitoring δ15N of primary producers is a feasible and important tool for monitoring wastewater management in Hong Kong.
published_or_final_version
Environmental Management
Master
Master of Science in Environmental Management

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13

Goldman, Jeffrey Scott. "Time and place specific policies for controlling ozone precursor nitrogen oxides in New England's electric power sector". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35422.

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14

Ma, Xiaobo, e 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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15

Chen, Wan-Ru. "Interactions of tetracycline antibiotics with dissolved metal ions and metal oxides". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24698.

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Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Huang, Ching-Hua; Committee Member: Kim, Jaehong; Committee Member: Pavlostathis, Spyros; Committee Member: Stack, Andrew; Committee Member: Yiacoumi, Sotira

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16

HAMA, PATRICIA. "Estudo da influencia da chuva acida na concentracao de aluminio em solos proximos a uma termoeletrica a carvao". reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10951.

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Made available in DSpace on 2014-10-09T12:46:00Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:04:46Z (GMT). No. of bitstreams: 1 07316.pdf: 5554844 bytes, checksum: f2a2161155dc5992abc29a9496405892 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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17

Mainord, Jacinda L. "Investigation of Ambient Reactive Nitrogen Emissions Sources and Deposition in the Columbia River Gorge National Scenic Area". PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3621.

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Anthropogenic reactive nitrogen is emitted into the atmosphere from fossil fuel combustion (nitrogen oxides) and agricultural activities (nitrogen oxides and ammonia). Nitrogen oxide emissions have long been controlled for their role in ambient air pollution and human health effects. However, reactive nitrogen deposition is less understood even though it can play a significant role in altering biodiversity, impairing ecosystem and biogeochemical function and degrading cultural artifacts. Although nitrogen deposition is a natural part of biogeochemical cycling, many ecosystems across the United States are at risk of exceeding the critical nitrogen deposition load. While nitrogen oxides are routinely measured in urban areas, far less is known in non-urban landscapes where ecosystems may be especially sensitive. Regional chemical transport models have been used to predict the impacts of ambient reactive nitrogen deposition in non-urban areas, but models have difficulty simulating reactive nitrogen due to poorly quantified emissions, especially from the agricultural sector. My research explores the speciated deposition of reactive nitrogen through monitoring and modeling in the unique field setting of the 150 mile Columbia River Gorge (CRG) located along the border of Oregon and Washington. This site is ideally suited for this investigation due to the large sources of reactive nitrogen at either end of the CRG and unique seasonally driven channel wind flow. Seasonally driven wind allowed us to look at the reactive nitrogen emissions flowing through the CRG to assess ambient the reactive nitrogen partitioning and deposition gradient. Using data collected by the United States Forest Service to control ambient haze in the CRG and our co-located nitrogen oxides (NOx) gas analyzer, we first characterized the influence of seasonal, bimodal wind distributions on the spatial distribution of reactive nitrogen. We found that during winter months with predominantly easterly winds, particulate nitrate and ammonium and gas-phase nitrogen dioxide levels create a gradient from the eastern end to the western end. Particulate nitrate and sulfate mass concentrations influence the CRG gradient during summer months with predominantly western winds. We also found that the magnitude of the impact from east is greater than the magnitude of impact from the west. When we compared our observations to regional chemistry transport models, we found that models are significantly under-predicting levels of reactive nitrogen in the CRG. This bias is not isolated to a single station within the Gorge, but throughout the whole Columbia Basin. Our results indicate that there are under-represented emissions in the region leading to this bias. Partly due to the bias in reactive N gas-phase species in the CRG, regional models have been underestimating the impact of gas-phase reactive N on dry N deposition. We conducted field studies at two sites within the CRG monitoring reactive nitrogen species (nitric oxide, nitrogen dioxide, ammonia, nitric acid, particulate nitrate, particulate ammonium, and particulate sulfate) as well as ozone and meteorological parameters. These measurements allowed us to conduct the first comprehensive analysis of reactive nitrogen partitioning and deposition in the CRG. Through our measurements, we found reactive nitrogen was higher in the spring than the summer. We found concentrations ranging from 0-15 ppbv ammonia, 0-7 ppbv nitric acid, 0-2 µg/m3 ammonium nitrate and 0-1 µg/m3 ammonium sulfate at the sites. Through the measurements of all these species, we evaluated the limiting gas-phase precursor to inorganic nitrogen particle formation. In the springtime, ammonia limits the formation of particulate reactive nitrogen; while in the summer, nitric acid and oxidized sulfur limit the formation of inorganic nitrogen particles. This suggests that there may be more sources of ammonia in the spring with fertilizer application or perhaps reactive nitrogen reservoirs are renoxified through thermal dissociation during warmer summer months. Our estimated deposition from gas and particle phase reactive nitrogen ranged from 0-0.14 kg N/ha per day. We also found that gas-phase reactive nitrogen plays the largest role in dry N deposition in the CRG with particle-phase contributing less than 15% of total dry N deposition. These results are important for land managers to understand the total impact of reactive nitrogen to non-urban areas. This research can inform mitigation strategies for haze formation, identify the major species and sources involved in dry N deposition and assess the potential impacts to ecosystems and cultural artifacts.

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18

Dolan, Bianca Christine. "Effects of Increased Nitrogen Deposition on the Dominance of Hedera helix in the Pacific Northwest". PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/680.

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Increased nitrogen deposition has been shown to promote the dominance of invasive species, and nitrogen deposition rates have steadily increased in most of the Western United States in recent years due to population increases. The purpose of this study was to determine if increased rates of nitrogen deposition are contributing to the success of Hedera helix in the Pacific Northwest. Plots were established in Lesser Park in Portland, Oregon and received monthly treatments of ammonium nitrate for one year. Growth, measured as change in percent cover, was compared between treated and untreated plots for both H. helix and native species. Additionally, a greenhouse experiment was employed wherein H. helix was grown in shared pots with two native species, Fragaria vesca and Polystichum munitum, and three treatment levels were compared; none, low, and high nitrogen. Relative growth rate was compared between treatments for each species after twelve weeks of treatment. Results from the greenhouse experiment were highly variable and no general conclusions could be drawn about the effects of increased nitrogen deposition on competition between H. helix and native species. In the field, treatment did not have a significant effect on growth but species did have a significant effect, as H. helix had a greater increase in percent cover than native species regardless of treatment. However, a marginally significant interaction was found between species and treatment. Native species cover actually increased in plots that received nitrogen addition and decreased in control plots, while H. helix had a slightly higher increase in cover in control plots. Though the growth of H. helix was significantly higher than the growth of native species in control plots, nitrogen addition caused the growth rates to converge towards more similar means in treated plots. Results indicate that increased nitrogen deposition may actually have a positive effect on the growth of native species by reducing the invasive potential of H. helix.

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19

Haynes, Comas Lamar. "Simulation of tubular solid oxide fuel cell behavior for integration into gas turbine cycles". Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/21797.

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20

Moss, Stuart Alan. "Nitrogen availability and pine seedling growth in organically- amended mine soils". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101135.

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Adequate supply and availability of nitrogen (N) is a major factor hindering successful revegetation of reclaimed surface mines. Because topsoils are often unrecoverable, “topsoil substitutes”, made up of overburden materials devoid of N, are often used on reclaimed surfaces. Four replications of seven surface treatments were applied to 12 m² plots of 2:1 sandstone:siltstone material on a reclaimed coal surface mine in Wise Co., VA: 1) fertilizer (168 kg/ha N, 147 kg/ha P, and 139 kg/ha K), 2) limed (7.8 Mg/ha), fertilized topsoil (30 cm deep), 3) 112 Mg/ha sawdust + fertilizer + 336 kg/ha slow-release N, and 4-7) lime-treated municipal sewage sludge at rates of 22, 56, 112, and 224 Mg/ha. Nitrogen availability after 40 mo (as determined by aerobic and anaerobic incubations) in sawdust- and sludge-amended soils was two to 20 times higher than in fertilized and topsoil-amended soils. Moisture holding capacity was nearly twice as high in sawdust-amended soils as in all other treatments. Soil nitrate (NO₃⁻) levels (0-20 cm layer) in excess of 75 μg/g were detected in the 112 and 224 Mg/ha sludge plots 28 mo after application. Stem volumes of three-year-old pitch X loblolly pines (Pinus rigida X taeda) were four times larger in soils amended with sawdust + slow-release N and were twice as large in soils amended with 22 and 56 Mg/ha sludge compared to fertilized-only seedlings. Increased seedling mortality was observed in the 112 and 224 Mg/ha sludge treatments, possibly due to high soluble salt levels and/or manganese deficiencies. The availability of N from sawdust + slow-release N or sludge (≤ 56 Mg/ha) is better than that of inorganic fertilizer for sustained tree growth. These amendments are recommended for reclamation to the extent that they are economically available.
M.S.

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21

Sears, Jill R. "Spatial Distribution of Nitrogen Oxides, Benzene, Toluene, Ethylbenzene, and Xylenes in Hillsborough County, Florida| An Investigation of Impacts of Urban Forests on Ambient Concentrations of Air Pollutants Associated with Traffic". Thesis, University of South Florida, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1548512.

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Urban air pollution is responsible for high levels of morbidity and mortality in exposed populations due to its effects on cardiovascular and respiratory function. Transportation-related air pollutants account for the majority of harmful air pollution in urban areas. Forests are known to reduce air pollution through their ability to facilitate dry deposition and atmospheric gas exchange. This work characterizes the interactions between transportation air pollutants and urban forests in Hillsborough County, Florida. A highly spatially resolved passive air sampling campaign was conducted to characterize local concentrations of nitrogen oxides, benzene, toluene, ethylbenzene, and xylenes (BTEX) in Hillsborough County, Florida. Sampling locations included a proportion of densely forested urban areas in order to determine the effects of Hillsborough County's urban forest resources on localized concentrations of selected transportation pollutants. Recommended approaches for the use of urban forests as an effective air pollution mitigation technique in Hillsborough County were generated based on results from the sampling campaign. Results show mean concentrations of 2.1 parts per billion and 6.5 µg/m3 for nitrogen oxides and total BTEX, respectively. High spatial variability in pollutant concentrations across Hillsborough County was observed, with the coefficient of variation found to be 0.61 for nitrogen oxides and 0.79 for total BTEX. Higher concentrations were observed along interstate highways, in urban areas of the county, and near select point sources in rural areas. Differences in concentrations within forested areas were observed, but were not statistically significant at the 95% confidence level. These results can be used to identify elements of urban design which contribute to differences in concentrations and exposures. This information can be used to create more sustainable urban designs which promote health and equity of the population.

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22

Jablonski, Leanne M. "Reproductive response to elevated CO2 : the roles of vegetative carbon storage, nitrogen and seed traits". Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34646.

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This study focused on the reproductive response to elevated CO2 of plants possessing below-ground storage. I tested the hypotheses that under elevated CO2: (1) Plants with greater non-foliar storage capacity win show more reproductive response and (2) The altered foliar physiology of carbon (C) and nitrogen (N) use will cause increases in seed number and quality. Carbon dioxide treatments of High (650 muL L-1) and Ambient (360 muL L-1) were used in a controlled environment, simulated growing season, and in a natural pasture community. Hypothesis 1 was tested experimentally using four Raphanus varieties that differed in hypocotyl and leaf sizes. N fertilization and harvest times were used to obtain a range of root:shoot ratios. Enhancements in vegetative leaf area rather than the hypocotyl predicted reproductive responsiveness to CO 2. However, after three years of CO2 exposure in the pasture, hypocotyl-storing Taraxacum officinale responded strongly in vegetative biomass which correlated with inflorescence size and number. Fitness was enhanced four-fold, while the leaf-storing Plantago major produced more ramets and had only a two-fold fitness increase. Hypothesis 2 was tested by examining the C and N physiology underlying the vegetative organs and seeds of the pasture plants. Under elevated CO2, photosynthesis increased two-fold and senescence was delayed. Total plant C:N ratio did not differ, suggesting N acquisition increased. N similarly limited seed number in all cases suggesting an unchanged Physiology of N use in reproduction. While morphology constrained total biomass response, provisioning to seeds increased as shown by higher seed mass and number and decreased variability in number and mass. In all cases, leaf mass increase under high CO2 corresponded with fitness increase. Phenology constrained response to CO 2 as there was no plasticity in flowering day in Raphanus and Plantago, while there were flowering delays but greater seed maturation rate in Tar

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23

Villinski, John Eugene. "Reductive dissolution of manganese (IV) oxides and precipitation of iron (III) : implications for redox processes in an alluvial aquifer affected by acid mine drainage". Diss., The University of Arizona, 2001. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2001_96_sip1_w.pdf&type=application/pdf.

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24

Sweeney, Andrew Jeffrey. "Computer Simulation and Optimization of the NOx Abatement System at the Radford Facility and Army Ammunition Plant". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/31404.

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This thesis discusses findings gained through work with the NOx abatement system at Radford Facility and Army Ammunition Plant (RFAAP). Removal of harmful substances from flue-gas emissions has garnered increased priority in the chemical industry in preceding decades, as governmental restrictions on these substances become more stringent and as national awareness concerning environmental quality and resource utilization continues to grow. These reasons make the study of NOx abatement an important and challenging endeavor. This work concerns itself specifically with reduction of NOx in flue-gas emissions from stationary sources. First we present an overview of current technology and approaches to controlling NOx for stationary sources. Next, we focus in on one particular approach to control of NOx within the context of a case study of the technology used at the Radford Facility and Army Ammunition Plant. RFAAP employs a scrubber/absorber tower followed in series by a selective catalytic reduction (SCR) reaction vessel in their NOx abatement system. We use as the method of study computer simulations within ASPEN Plus, a process simulation software package for chemical plants. We develop three different models with which to characterize NOx abatement at RFAAP, a conversion model, an equilibrium model and a kinetic model. The conversion-reaction model approximates the absorption and SCR reactions with constant percentage extent-of-reaction values. Though useful for initial investigation and mass balance information, we find the conversion model's insensitivity to process changes to be unacceptable for in-depth study of the case of NOx absorption and SCR. The equilibrium-reaction model works on the assumption that all the reactions reach chemical equilibrium. For the conditions studied here, we find the equilibrium model accurately simulates NOx absorption but fails in the case of SCR. Therefore, we introduce a kinetic-reaction model to handle the SCR. The SCR reactions prove to be highly rate-dependant and the kinetic approach performs well. The final evolution of the ASPEN Plus simulation uses an equilibrium model for the absorption operation and a kinetic model for the SCR. We explore retrofit options using this combined model and propose process improvements. We end this work with observations of the entire project in the form of conclusions and recommendations for improving the operation of the NOx abatement system through process-parameter optimization and equipment-retrofit schemes.

By leading the reader through the process by which we arrived at a successful and highly informative computer model for NOx absorption and SCR, we hope to educate the reader on the subtleties of NOx abatement by absorption and SCR. We attempt to break down the numerous complex processes to present a less daunting prospect to the engineer challenged with the application of current NOx removal technology. In addition, we introduce the reader to the power and usefulness of computer modeling in instances of such complexity. The model teaches us about the details of the process and helps us develop concrete information for its optimization. Ideally, the reader could use a similar approach in tackling related operations and not confine the usefulness of this thesis to NOx absorption and SCR.

The audiences that we think would benefit from exposure to this thesis are the following: Â· Environmental engineers with a NOx problem; Â· Process engineers interested in optimization tools; Â· Design engineers exploring flue-gas treatment options; Â· Combustion engineer desiring to learn about SCR; Â· Chemists and mathematicians intrigued by the complexities of NOx absorption chemistry.
Master of Science

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25

Norwood, Sasha Norien. "Characterization of Nano-scale Aluminum Oxide Transport Through Porous Media". PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/981.

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Land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers. Although nutrient rich, biosolids have been found to contain high concentrations of emerging contaminants (e.g. pharmaceuticals, personal care products) while containing a significant fraction of inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of these nano-sized colloidal materials through the soil column and into our surface and groundwater bodies. Transport of emerging pollutants of concern through the soil column, at minimum, is impacted by colloidal properties (e.g. chemical composition, shape, aggregation kinetics), solution chemistry (e.g. pH, ionic strength, natural organic matter), and water flow velocity. The purpose of this current research was to characterize the long-term transport behavior of aluminum oxide nanoparticles (Al2O3) through a natural porous media with changes in pH, aqueous-phase concentration, pore-water velocity and electrolyte valence. Additionally, deposition rates during the initial stages of deposition were compared to several models developed based on colloid filtration theory and DLVO stability theory. Benchtop column laboratory experiments showed that, under environmentally relevant groundwater conditions, Al2O3 nanoparticles are mobile through saturated porous media. Mobility increased under conditions in which the nanoparticles and porous media were of like charge (pH 9). Changes in linear pore water velocity, under these same high pH conditions, showed similar transport behavior with little mass retained in the system. Deposition is believed to be kinetically controlled at pH 9, as evidenced by the slightly earlier breakthrough as flow rate increased and was further supported by observed concentration effects on the arrival wave following several stop flows. While lower aqueous-phase concentrations resulted in significantly longer breakthrough times, the total mass retained in the system was found to be independent of concentration. Additionally, experimental deposition rate coefficients (kd), used to describe deposition kinetics under "clean bed" conditions, were similar across the aqueous-phase concentrations studied. The use of calcium chloride electrolyte solution in transport studies resulted in enhanced mobility relative to potassium chloride suggesting that changes in groundwater solution chemistry could impact mobility of contaminants associated with biosolids. Predicted deposition rate coefficients, using three different models, were found to under- or over-predict values relative to those experimentally determined values depending on the model. This current research has shown that nanocolloids associated with biosolids, specifically Al2O3, are mobile through saturated porous media. Given the ubiquity of nanocolloidal materials, particularly engineered nanomaterials, coupled with the expected increase in land-application of biosolids, a clear understanding of their transport and fate is prudent to understanding the potential impact these emerging pollutants may have on our surface and groundwater bodies.

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26

Johnson, Terrence G. "A model of nitrate leaching from agricultural systems in the northern neck of Virginia". Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/37887.

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A model (VTCROPS) was developed to simulate the long-term effects of nitrogen (N) leaching to groundwater in the Northern Neck region of Virginia, and ultimately to the Chesapeake Bay. VTCROPS simulates N fate and transport in a soil-plant-atmosphere continuum in a vertical slice between two crop rows, enabling consideration of nonuniform fertilizer placement and root growth patterns. VTCROPS models atmospheric, soil and crop subsystems. Atmospheric conditions (rainfall, temperature, solar radiation) may be directly input by the user or generated using a stochastic climatic generator. The soil subsystem simulates runoff, infiltration, drainage and soil-water redistribution, N immobilization, nitrification, mineralization, denitrification and advective N transport. The crop subsystem simulates plant N uptake, and vegetative and reproductive growth in response to soil and climatic factors, explicitly for maize or wheat. VTCROPS simulates soybean in a crop rotation empirically accounting for leaf area and root growth. The model is capable of simulating long-term cropping sequences under minimum and conventional tillage practices for continuous maize or for rotations involving maize, wheat, soybean and fallow. Critical internal model parameters were calibrated through comparison of output to field data. The sensitivity of output to input variables was determined. Model output is most sensitive to the climatic variables. Model predicted crop performance variables — grain and total dry matter yields and N content — and soil N content were compared with available field data from two sites over a three year period for maize. Data from six sites over a one year period were tested for wheat. Predictions for maize and total N content were fairly accurate, with a tendency to greater error in dry years. Predictions for wheat were somewhat less accurate, but incomplete field data precluded determining the source of discrepancies. Long-term model predictions, for two year crop rotations with minimum and conventional tillage, were evaluated by comparing performance variables with literature values. Appropriate responses were obtained for N transformation processes. Mass conservation for soil-water and N were good. Maize performance variables were within the range of literature values, and were higher under minimum till. Wheat yields and N contents were somewhat higher than values reported in the literature. Nitrogen load is correlated to drainage and water use over the short run, and to rainfall and drainage over longer periods. Minimum tillage did not increase N load to groundwater. Over a year nitrogen load was strongly periodic, with most leaching taking place from January through April. More than 50% of the N load over a rotation was lost during an extended fallow period that followed soybeans. Nitrogen load increased with fertilizer rates, however, N leaching fraction was optimal around rates of 150 — 200 kg/ha. The model was applied to the Virginia counties of Richmond, Westmoreland, Lancaster, King George and Northumberland to assess the potential for long term N leaching to groundwater. Soil surveys indicated that 34 soil map units occurred within 123,000 hectares of cultivated land. In order to reduce the number of simulations, principal component analysis and cluster analysis were employed to subdivide the cultivated area into 10 land units based on different soil properties. Historical climatic data from the area was used to calibrate the stochastic climatic generator. Analyses were performed to determine long-term crop performance and N loads to ground and surface waters in the study area over a 26 year period (13 rotations). Two management systems were applied to the land units. The first management system consisted of a rotation of minimum tilled maize, conventionally tilled wheat, minimum tilled soybeans and a fallow period. The second management system had a similar cropping sequence, but all crops were conventionally tilled. In both cases, fertilizer was applied at a rate of 150 kg-N/ha/crop. With the exception of two land units, mean yield, water use and N uptake over the simulation was fairly uniform among the land units. Runoff and drainage were highly variable between land units and over time within units. Mineralization, denitrification and N load were highly variable both between land units and over time. Nitrogen load ranged from 66 to 131 kg/ha/rotation between land units. Long-term average N loads and N concentrations from the cultivated area and from the total area of the study region were estimated. For this analysis it was assumed that 80% of the cultivated area was under minimum till and 20% under conventional tillage. An area-weighted average of 5.4 million kg-N/ha/year or 29% of total N applied is discharged to groundwater with an average drainage concentration of 9.9 mg/L. The average N concentration from the study area (including uncultivated areas) to groundwater is estimated at 5.1 mg/L. Average N concentration to the Chesapeake Bay from all sources, after dilution with runoff is 4.5 mg/L which is lower than the drinking water standard for nitrate N of 10 mg/L. The possibility of using sewage sludge as a replacement for, or in consort with N fertilizer was investigated for a typical land unit, under a conventionally tilled maize-wheat- soybean-fallow rotation. Simulations were conducted with 100%, 50% and 0% sludge (C—N ratio of 12). With fertilizer N augmenting the sludge, the total N input (250 kg/ha) was the same for each treatment. Mean yields were similar for 50% and zero sludge, but lowered by 10% and 16%, respectively, for maize and wheat with 100% sludge. Discrepancies in yields were attributed to the fact that mineralization rates of sludge are not high enough to supply the crop N requirement during periods of peak uptake. Nitrate leaching was reduced by 41 and 25% with 100 and 50% sludge applications, respectively.
Ph. D.

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27

Downing, T. G. "The role of nitrogen in the regulation of microcystin content in Microcystis aeruginosa". Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50523.

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Thesis (PhD)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Several genera of cyanobacteria produce a range of toxins. The increased rate of eutrophication of surface fresh waters due to anthropogenic inputs has resulted in more frequent and severe cyanobacterial bloom events. Such bloom events make impoundments unsuitable for recreational use and increase the cost of production of potable water due to the necessity for removal of toxins released from cells during the purification process. Microcystis aeruginosa is the major freshwater bloom-forming toxic cyanobacterium. Concentrations of the hepatotoxin, microcystin, are highly variable in blooms. Published literature on environmental conditions leading to increased microcystin production was often contradictory and in many cases did not consider all relevant parameters. However, environmental nitrogen and phosphorus, temperature and light, and growth rate were implicated in regulation of toxin content. The purpose of this work was therefore to investigate environmental factors (specifically nitrogen and phosphorus) and cellular activities (specifically carbon fixation and nitrogen uptake rates and growth rate) involved in the modulation of microcystin production in M. aeruginosa in order to clarify the role of these parameters, and in an attempt to identify regulatory mechanisms for microcystin production. Environmental nitrogen, phosphorus and growth rate were shown to co-modulate microcystin production in M. aeruginosa. Adequate phosphorus is required for photosynthetic carbon fixation. Phosphorus uptake by M. aeruginosa is strongly correlated with carbon fixation rate. Although microcystin content increased with increasing nitrogen:phosphorus ratios in culture medium, under phosphorus limitation microcystin content was lower irrespective of nitrogen concentrations. This observation and the requirements for fixed carbon for nitrogen assimilation therefore prompted investigation of the effects of cellular carbon fixation and nitrogen uptake in the modulation of microcystin production. Microcystin production was found to be enhanced when nitrogen uptake rate relative to carbon fixation rate was higher than that required for balanced growth. The cellular nitrogen:carbon ratio above which microcystin concentrations increased substantially, corresponded to the Redfield ratio for balanced growth. Investigation of potential regulatory mechanisms involving the cyanobacterial nitrogen regulator, NtcA, yielded putative NtcA binding sites indicative of repression in the microcystin synthetase gene cluster. In culture, the polypeptide synthetase module gene, mcyA, and ntcA were inversely expressed as a function of carbon-fixation:nitrogen-uptake potential. However, no increase or decrease in microcystin production could be linked to either glutamine, glutamate or a-ketoglutarate, metabolites that are involved in regulation of ntcA. The role of NtcA in regulation of microcystin production could therefore not be confirmed. In conclusion, these data suggest that microcystin production is metabolically regulated by cellular C:N balance and specific growth rate. The primary importance of nitrogen and carbon was demonstrated by a simple model where only nitrogen uptake, carbon fixation and growth rate were used to predict microcystin levels. The model also explains results previously described in literature. Similarly, an artificial neural network model was used to show that the carbon fixation dependence on phosphorus allows accurate prediction of microcystin levels based on growth rate and environmental nitrogen and phosphorus.
AFRIKAANSE OPSOMMING: Verskeie genera van sianobakterieë produseer 'n verskeidenheid van toksiene. Die toename in die tempo van eutrofikasie van varswater oppervlaktes as gevolg van antropogeniese insette veroorsaak al hoe meer en al hoe erger sianobakteriële infestasies. Dit veroorsaak probleme vir ontspanninggebruik van hierdie waters en verhoog die koste van produksie van drinkbare water as gevolg van die noodsaak om die toksiene wat deur die selle gedurende die suiweringsproses vrygelaat word te verwyder. Microcystis aeruginosa is die belangrikste varswater bloeisel-vormende toksiese sianobakterium. Die konsentrasie van die hepatotoksien mikrosistien is hoogs varieerbaar in sulke bloeisels. Gepubliseerde literatuur oor die omgewingskondisies wat lei na verhoogde mikrosistienproduksie is dikwels weersprekend en neem in vele gevalle nie al die relevante parameters in ag nie. Desnieteenstaande word omgewingstikstof, fosfor, temperatuur en lig, asook groeisnelheid, geïmpliseer in die regulering van toksieninhoud. Die doel van hierdie navorsing was dus om omgewingsfaktore (spesifiek stikstof en fosfor) en sellulêre aktiwiteite (spesifiek koolstoffiskering en die snelheid van stikstofopname en van groei) betrokke by die modulering van mikrosistienproduksie in M. aeruginosa te ondersoek in 'n poging om die rol van hierdie parameters te verstaan en om regulatoriese meganismes vir mikrosistienproduksie te identifiseer. In hierdie studie is aangetoon dat omgewingstikstof en fosfor sowel as groeisnelheid mikrosistienproduksie in M. aeruginosa ko-moduleer. Genoegsame fosfor word benodig vir fotosintetiese koolstoffiksering. Fosforopname deur M. aeruginosa korreleer sterk met die snelheid van koolstoffiksering. Alhoewel mikrosistieninhoud toegeneem het met 'n toename in die stikstof:fosfor verhouding in die kultuurmedium, was die mikrosistieninhoud onder kondisies van fosforlimitering laer ongeag die stikstofkonsentrasie. Hierdie waarneming, tesame met die noodsaak van gefikseerde koolstof vir stikstofassimilering, het gelei na 'n studie van die effekte van sellulêre koolstoffiksering and stikstofopname op die modulering van mikrosistienproduksie. Dit is gevind dat mikrosistienproduksie verhoog was wanneer die snelheid van stikstofopname relatief tot die snelheid van koolstoffiksering hoër was as die waarde wat benodig word vir gebalanseerde groei. Die sellulêre stikstof:koolstof verhouding waarbo mikrosistienkonsentrasies beduidend verhoog is stem ooreen met die Redfield verhouding vir gebalanseerde groei. 'n Ondersoek na potensiële reguleringsmeganismes waarby die sianobakteriële stikstofreguleerder NtcA betrokke is het gelei na die ontdekking van moontlike NtcA bindingseteis; dit kan dui op die repressie van die mikrosistiensintetase geengroepering. Onder kultuurkondisies is gevind dat die geen vir die polipeptiedsintetase module, mcyA, en ntcA omgekeerd uitgedruk word as 'n funksie van koolstofopname:stikstofopname potensiale. Geen toename of afname in mikrosistienproduksie kon egter gekoppel word aan óf glutamien, óf glutamaat, óf a-ketoglutaraat nie, metaboliete wat betrokke is by die regulering van ntcA. Die rol van NtcA in die regulering van mikrosistienproduksie kon dus nie bevestig word nie. Die gevolgtrekking is dus gemaak dat mikrosistienproduksie metabolies gereguleer word deur die C:N balans en die spesifieke groeisnelheid. Die primêre belang van stikstof en koolstof is gedemonstreer deur 'n eenvoudige model waarin slegs stikstofopname, koolstoffiksering en groeisnelheid gebruik word om mikrosistienvlakke te voorspel. Die model verklaar ook resultate wat tevore in die literatuur beskryf is. Soortgelyk is 'n artifisiële neurale netwerkmodel gebruik om te toon dat die afhanklikheid van koolstoffiksering van fosfor akkurate voorspelling van mikrosistienvlakke gebaseer of groeisnelheid en omgewingstikstof en fosfor moontlik maak.

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TORRES, JARDÓN RICARDO. "COMPARATIVE ASSESSMENT OF THE SENSITIVITY OF OZONE TO NITROGEN OXIDES AND VOLATILE ORGANIC COMPOUNDS IN TWO DISSIMILAR METROPOLITAN AREAS OF NORTH AMERICA: CINCINNATI, OH (U.S.A.) AND MEXICO CITY, DF (MEXICO)". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100032213.

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29

David, Clive Addison. "Post-harvest floor changes and nitrogen mobilization in an Engelmann spruce-subalpine fir forest". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26986.

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Engelmann spruce-subalpine fir [Picea engelmannii Parry ex Engelm.-Abies lasiocarpa (Hook.) Nutt.] (ESSF) forests occupy large portions of western North America, and of British Columbia (B.C.) in particular. These areas represent a harsh environment for plant growth. The ESSF forests of B.C. have presented serious problems of regeneration following harvesting; several factors stimulated speculation as to whether N supply limitations were involved. This study was intended to highlight the post-harvest N dynamics of an ESSF forest, and the implications of the latter for silvicultural practices. Its general objectives included characterization of the post-harvest assart effect, and investigation of the N status and growth of advance regeneration. These were achieved by means of a comparative study of an age sequence of harvested sites. The assart effect lasted for at least eight years after harvesting, with a peak of change between years three and six. There were no major physical changes in the forest floor. Low C/N ratios between 19 and 32 were believed to have contributed to increased N availability. ESSF forests may have a generally higher level of N availability than previously supposed. The advance regeneration benefited from the assart effect. Nutrient uptake appeared to increase generally from at least three years after harvesting; increases of up to 78% were noted for N. There appeared to be no general macronutrient or micronutrient limitation to growth. However, evidence of S deficiencies was encountered in some trees. Moreover, the critical levels used for N may be in need of revision. A revised critical level of 1.40% for foliar N concentrations is proposed for subalpine fir advance regeneration. If this is accurate, regeneration may have been at least temporarily N-limited from year eight after harvesting. A more rigorous investigation of these possibilities is needed. The cutting method applied to the sites approximated a one-cut shelterwood method. The method as encountered in this study should not be considered a viable silvicultural option for similar ESSF forests. Its successful application would involve some degree of forest floor manipulation to improve seedbed conditions and soil microclimatic regimes. The findings of this study demonstrate that the environmental and biological characteristics of ESSF forests make high levels of planning and care a prerequisite for the success of silvicultural practices. The question of what comprises realistic growth and yield expectations of second-rotation stands in the ESSF zone needs to be addressed urgently.
Forestry, Faculty of
Graduate

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30

Rao, Meenakshi. "Investigating the Potential of Land Use Modifications to Mitigate the Respiratory Health Impacts of NO2| A Case Study in the Portland-Vancouver Metropolitan Area". Thesis, Portland State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10131547.

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Abstract (sommario):

The health impacts of urban air pollution are a growing concern in our rapidly urbanizing world. Urban air pollutants show high intra-urban spatial variability linked to urban land use and land cover (LULC). This correlation of air pollutants with LULC is widely recognized; LULC data is an integral input into a wide range of models, especially land use regression models developed by epidemiologists to study the impact of air pollution on human health. Given the demonstrated links between LULC and urban air pollution, and between urban air pollution and health, an interesting question arises: what is the potential of LULC modifications to mitigate the health impacts of urban air pollution?

In this dissertation we assess the potential of LULC modifications to mitigate the health impacts of NO₂, a respiratory irritant and strong marker for combustion-related air pollution, in the Portland-Vancouver metropolitan area in northwestern USA. We begin by measuring summer and winter NO₂ in the area using a spatially dense network of passive NO₂ samplers. We next develop an annual average model for NO₂ based on the observational data, using random forest—for the first time in the realm of urban air pollution—to disentangle the effects of highly correlated LULC variables on ambient NO₂ concentrations. We apply this random forest (LURF) model to a 200m spatial grid covering the study area, and use this 200m LURF model to quantify the effect of different urban land use categories on ambient concentrations of NO₂. Using the changes in ambient NO₂ concentrations resulting from land use modifications as input to BenMAP (a health benefits assessment tool form the US EPA), we assess the NO₂-related health impact associated with each land use category and its modifications. We demonstrate how the LURF model can be used to assess the respiratory health benefits of competing land use modifications, including city-wide and local-scale mitigation strategies based on modifying tree canopy and vehicle miles traveled (VMT).

Planting trees is a common land cover modification strategy undertaken by cities to reduce air pollution. Statistical models such as LUR and LURF demonstrate a correlation between tree cover and reduced air pollution, but they cannot demonstrate causation. Hence, we run the atmospheric chemistry and transport model CMAQ to examine to what extent the dry deposition mechanism can explain the reduction of NO₂ which statistical models associate with tree canopy.

Results from our research indicate that even though the Portland-Vancouver area is in compliance with the US EPA NO₂ standards, ambient concentrations of NO₂ still create an annual health burden of at least $40 million USD. Our model suggests that NO₂ associated with high intensity development and VMT may be creating an annual health burden of $7 million and $3.3 million USD respectively. Existing tree canopy, on the other hand, is associated with an annual health benefit of $1.4 million USD. LULC modifications can mitigate some fraction of this health burden. A 2% increase in tree canopy across the study area may reduce incidence rates of asthma exacerbation by as much as 7%. We also find that increasing tree canopy is a more effective strategy than reducing VMT in terms of mitigating the health burden of NO₂.

CMAQ indicates that the amount of NO₂ removed by dry deposition is an order of magnitude smaller than that predicted by our statistical model. About one-third of the difference can be explained by the lower NO₂ values predicted by CMAQ, and one-third may be attributable to parameterization of stomatal uptake.

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31

Smith, Ronald David. "The influence of air mass origin on the wet deposition of nitrogen to Tampa Bay, Florida". [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000099.

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32

Bhathena, Jasmine. "The physical and physiological effects of nitrogen and phosphorus limitation on a pulp and paper mill effluent biotreatment microbial community /". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80228.

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Abstract (sommario):

The influence of nitrogen (N) and phosphorus (P) limitation on pulp and paper mill activated sludge (AS) floc properties was studied using a bioreactor fed with synthetic Kraft mill effluent. The bioreactor and synthetic effluent were designed and shown to perform like the real mill system providing the AS, establishing the in vivo relevance of the results. Limitation of either N or P produced inadequate effluent biotreatment, shown by poor BOD5 and suspended solids removal, and by decreased biomass health, performance, and floc settling. Greatly enhanced poly-beta-hydroxybutyrate (PHB) (but not carbohydrate or extracellular polymeric substances [EPS]) synthesis was the common response of the floc microbial community to N limitation over many days. In contrast, P-limitation increased total carbohydrate and EPS, but not PHB.
N limitation, but not P limitation, caused the net floc surface charge to be much more negative, while P-limitation, but not N-limitation, increased the floc bound water content and surface hydrophobicity. Thus, in real pulp and paper mill AS systems, careful manipulation of N or P additions may be useful to optimize the key process of charged polymer-assisted AS dewatering.

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33

Sears, Jill. "Spatial Distribution of Nitrogen Oxides, Benzene, Toluene, Ethylbenzene, and Xylenes in Hillsborough County, Florida: An Investigation of Impacts of Urban Forests on Ambient Concentrations of Air Pollutants Associated with Traffic". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4842.

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Abstract (sommario):

Urban air pollution is responsible for high levels of morbidity and mortality in exposed populations due to its effects on cardiovascular and respiratory function. Transportation-related air pollutants account for the majority of harmful air pollution in urban areas. Forests are known to reduce air pollution through their ability to facilitate dry deposition and atmospheric gas exchange. This work characterizes the interactions between transportation air pollutants and urban forests in Hillsborough County, Florida. A highly spatially resolved passive air sampling campaign was conducted to characterize local concentrations of nitrogen oxides, benzene, toluene, ethylbenzene, and xylenes (BTEX) in Hillsborough County, Florida. Sampling locations included a proportion of densely forested urban areas in order to determine the effects of Hillsborough County's urban forest resources on localized concentrations of selected transportation pollutants. Recommended approaches for the use of urban forests as an effective air pollution mitigation technique in Hillsborough County were generated based on results from the sampling campaign. Results show mean concentrations of 2.1 parts per billion and 6.5 µg/m3 for nitrogen oxides and total BTEX, respectively. High spatial variability in pollutant concentrations across Hillsborough County was observed, with the coefficient of variation found to be 0.61 for nitrogen oxides and 0.79 for total BTEX. Higher concentrations were observed along interstate highways, in urban areas of the county, and near select point sources in rural areas. Differences in concentrations within forested areas were observed, but were not statistically significant at the 95%#37; confidence level. These results can be used to identify elements of urban design which contribute to differences in concentrations and exposures. This information can be used to create more sustainable urban designs which promote health and equity of the population.

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34

Ling, Ge. "Assessment of nitrate leaching in the unsaturated zone on Oahu". Thesis, Water Resources Research Center, 1996. http://hdl.handle.net/10125/21929.

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Groundwater contamination caused by agricultural fertilization is a widely recognized problem. In Hawaii, nitrogen fertilization from pineapple and sugarcane fields has posed a threat to several basal aquifers and has been implicated in coastal algae blooms. The concentration of nitrate-N in the Pearl Harbor basin on the island of Oahu was below 2.3 mg/L in the 1950’s and 1960’s, and has increased to as much as 7.6 mg/L in 1992 to 1994. The objective of this dissertation research is to develop a practical methodology for realistically estimating nitrate leaching from fertilized agricultural lands. Numerous mechanisms have impact on the distribution and migration of nitrate in the soil. Nitrogen fertilizer undergoes many N transformations and interactions with the soil and the plant after applications. In this study, an analysis of soil samples was performed to understand the leaching process of nitrate in the root zone of three different cropped fields in Hawaii. A detailed discussion is given to address various factors which control the nitrate transport process. To judge the sampling plan in relation to spatial variation, the field measurements were evaluated statistically by an uncertainty index, which is represented as the density of samples required for the estimate of sample mean of the nitrate concentration to fall within a defined limit of accuracy. In order to predict the effect of nitrogen fertilization on the groundwater contamination with very limited input data, a simple, analytical, lumped parameter model (LPM), was developed. The model can estimate the average nitrate leaching from the root zone in response to agricultural practices, N transformations and other related processes. The model was tested against the field data and two detailed numerical models, LEACHM-N and CERES-Maize. It provides an alternative way to assess nitrate leaching from the root zone with acceptable accuracy. A listing of the program is provided in Appendix 2. Owing to the complex nature of nitrogen behavior in the unsaturated zone, some degree of uncertainty is involved in the development of modeling approaches. In this study, five major sources of uncertainty were identified. These are: uncertainty due to spatial variation, uncertainty related to the accuracy of the input data, uncertainty due to simplifications in the development of the models, uncertainty due to the modeling parameters, and uncertainty due to the complexity of the unsaturated zone in Hawaii. The impact of these uncertainties on simulation results is evaluated.
Thesis (Ph. D.)--University of Hawaii at Manoa, 1996.
Includes bibliographical references (leaves 202-215).
UHM: Has both book and microform.
Water Resources Research Center, University of Hawaii at Manoa

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35

Laurinaitis, Kastytis. "Dyzelinio variklio darbo proceso homogeniniu oro ir bioetanolio mišiniu tyrimas". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140630_092709-45813.

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Darbe tirta tiekiamo oro temperatūros, deginių recirkuliacijos ir degalų savybių įtaka suslėgimu uždegamo homogeninio oro – bioetanolio mišinio degimo procesui, variklio darbo ir deginių emisijos rodikliams. Nustatytos variklio darbo homogeniniu oro – bioetanolio mišiniu maksimalios apkrovos zona, kurią riboja slėgio didėjimo greitis ir susidarantis detonacinis degimas. Gautieji rezultatai varikliui veikiant bioetanoliu, lyginti su rezultatais gautais varikliui veikiant baziniais degalais – benzinu. Dyzeliniam varikliui dirbant homogeniniu oro ir bioetanolio mišiniu, keičiant tiekiamo oro temperatūrą, naudojant deginių recirkuliaciją ir įmaišant 20 % reaktyvinių degalų, azoto oksidų emisijos lieka dešimtis kartų mažesnės negu tradicinio dyzelinio variklio. Slegiamo homogeninio oro – bioetanolio mišinio užsiliepsnojimui valdyti pirmą kartą panaudoti reaktyviniai degalai.
It was found that the intake air temperature, exhaust gas recirculation and fuel properties have the influence on the combustion characteristics of homogeneous air – bioethanol mixture, engine performance and emissions. The operating region was found at which critical rate of pressure rise was unacceptably high and engine worked at “knocking” combustion. In order to assess the combustion process in homogeneous charged compression ignition (HCCI) mode fuelled with the air – bioethanol mixture, it was compared whit the combustion process in HCCI mode fuelled with the air – gasoline mixture. When the diesel engine works in HCCI mode fuelled with air – bioethanol mixture, the nitrogen oxides can be reduced more than 10 times compared with normal diesel operation. For the first time, to control the autoignition of compressed homogeneous air and bioethanol mixture, the JET A1 fuel was simultaneously added in to combustible mixture in this study.

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36

周厚華 e Donna Chaw. "Biochemical changes in the fermentation bedding of the "pig-on-litter"method of pig farming: with special emphasison biodegradation of nitrogen compounds and odour production". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B43893740.

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37

Ndobeni, Afika. "Effect of temperature and carbon to nitrogen ratio on the performance of an upflow anaerobic sludge blanket reactor treating sugarcane molasses". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2622.

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Abstract (sommario):

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2018.
The sugar industry contributes to the development of the economy in many countries, including South Africa. The wastewater generated by this industry has a high pollution load, and therefore requires treatment before discharge to the environment. The primary aims of this study were to determine the performance of an upflow anaerobic sludge blanket (UASB) reactor treating sugarcane molasses and to develop an empirical model to predict the behaviour of the UASB in terms of chemical oxygen demand (COD) removal and biogas production. A UASB (46 L working volume) was inoculated with granular sludge from the brewery industry and was used to investigate the treatment of synthetic sugar industry wastewater with an average COD of 4101 mg/L. The experiments were designed using Design-Expert® Software Version 10. The analysis of variance for the models and the optimisation of reactor temperature and feed carbon to nitrogen (C/N ratio) were carried out using response surface methodology. The UASB was operated at constant hydraulic retention time and organic loading rate of 2.04 days and 2.01 kg/m3.d, respectively. A start-up period of 22 days was required to reach steady-state. The developed empirical models for total COD removal efficiency and biogas production rate were found to be statistically significant with Prob > F values of 0.0747 and 0.0495 and the determination coefficients (R2) were found to be 0.80 and 0.65, respectively. The optimal conditions were found to be at a temperature of 38oC and C/N ratio of 22 mgTOC/mgTN. The corresponding removal efficiencies in terms of total COD, five day biological oxygen demand, total nitrogen, total phosphorus, and sulphate was 77.7, 85.9, 99.2, 44.4 and 57.2%, respectively. Biogas was produced at a rate of 0.832 L/L.d with a methane, carbon dioxide and molecular oxygen content of 65.2, 32.8 and 0.6%. Results suggest that UASBs may offer a feasible option for reducing the organic strength of sugar industry wastewater, while simultaneously generating methane-rich biogas.

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38

Stewart, Alan V. "Plant breeding aspects of ryegrasses (Lolium sp.) infected with endophytic fungi". Phd thesis, University of Canterbury. Lincoln College, 1987. http://theses.lincoln.ac.nz/public/adt-NZLIU20071005.172250/.

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Some aspects of the presence of systemic endophytic fungi in agriculturally important New Zealand grasses were studied in relation to plant breeding. Seedling resistance to adult Argentine stem weevil feeding in perennial ryegrass, Italian ryegrass and tall fescue was found to be related to the presence of their respective Acremonium endophytes in the seed rather than to plant genetic resistance. In addition a study of perennial ryegrass revealed that this resistance was independent of endophyte viability. The seedling resistance conferred by the endophyte of Italian ryegrass was found to be beneficial for field establishment. This endophyte differs from that in perennial ryegrass and tall fescue in that it does not confer resistance to Argentine stem weevil on mature plants, but only on seedlings. The extent of plant genetic seedling tolerance to adult Argentine stem weevil feeding was limited to broad inter-specific differences, with tall fescue more tolerant than perennial ryegrass and both of these more tolerant than Italian ryegrass. This ranking corresponds with previous observations on feeding preference on mature plants. A study of factors affecting the concentration of endophyte mycelia in infected seed of perennial ryegrass revealed that plant genetic factors had little effect. The major factors studied were: 1) the endophyte concentration in the maternal parent plant directly influenced the endophyte concentration in the seed. 2) nitrogen fertilizer applications to a seed crop reduced the concentration of mycelia in the seed, with earlier applications having a greater effect. 3) application of the fungicide propiconazole (Tilt) to a seed crop reduced the endophyte concentration in the seed. 4) the endophyte concentration in the seed was found to directly influence the endophyte concentration in seedlings, six month old plants and that of seed harvested from a first year seed crop. As there have been no previous reports of tetraploid perennial ryegrass cultivars with endophyte an experiment was conducted to determine if these could be developed by the standard procedure of colchicine treatment. The results revealed that endophyte was retained following colchicine treatment.

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39

Cleghorn, Charles 1970. "Effect of soil covers on coal waste dumps in KwaZulu-Natal on abiotic factors and bacteria causing acid mine drainage". Thesis, Stellenbosch : Stellenbosch University, 1997. http://hdl.handle.net/10019.1/55521.

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Thesis (MSc)--Stellenbosch University, 1997.
ENGLISH ABSTRACT: The activity of iron-oxidizing bacteria, for example, Thiobacillut. ferrooxidans, in the outer layers of coal waste dumps results in the oxidation of pyrite with the formation of large volumes of acid mine drainage. The process requires atmospheric oxygen and moisture. Acid mine drainage may possibly be controlled by creating unfavourable environmental conditions in dumps for the iron-oxidizing bacteria. The present research investigated the possibility of inhibiting these bacteria and consequently acid formation in coal waste dumps by means of different dump construction techniques. Physical and chemical conditions, acid formation and populations of four groups of bacteria which might produce acid were studied in the outer layers of ten differently constructed pilot scale coal waste dumps at the Kilbarchan Mine near Newcastle, Kwazulu-Natal, from September 1993 to July 1995. Dump covers consisting of a 30-cm or 70-cm layer of Estcourt soil of low permeability covered with 70 cm or 30 cm, respectively, of more permeable Avalon soil produced anaerobic conditions in the dumps throughout most of the 22 months of the test period, as did a cover of 70 cm compacted plus 30 cm uncompacted Avalon soil alone. An uncoMpacted 30-cm or compacted 50- cm Avalon soil cover proved ineffective in causing prolonged anaerobic conditions. Uncovered dumps showed only slight reduction of oxygen in the coal waste after heavy rains. Pockets of acidity were detected on several occasions in the coal waste below the 50-cm Avalon soil layer from the time of construction and progressively increasing acidity in the uncovered dumps and the waste below the 30-cm Avalon soil cover. Iron-oxidizing bacterial populations of the T. ferrooxidans type have tended to be higher in the uncovered dumps and Avalon soil-covered dumps showing acidification than in the non-acidified dumps covered with 1 m of Avalon soil or Avalon and Estcourt soil. Associated populations of iron-oxidizing bacteria of the Metallogenium type, acidophilic and non-acidophilic thiosulphate-oxidizing bacteria were generally low in the coal waste of the dumps. Thus, five of the soil covers, all with a thickness of 1 m, but not covers with a thickness of 0.5 m or less, proved effective for almost 2 years in inhibiting the diffusion of oxygen to the underlying coal waste in the pilot scale dumps and also appeared to suppress the populations of iron-oxidizing bacteria believed to be implicated in acid formation in the coal waste. These results suggest that coal waste dumps in South Africa should be covered with soil layers of 0.5-1.0 m thick to prevent the generation of acid mine drainage.
AFRIKAANSE OPSOMMING: Die aktiwiteit van ysteroksiderende bakteriee soos Thiobacillus ferrooxidans, in die buitenste lae van steenkoolafvalhope, veroorsaak die oksidasie van piriet met die gevolg dat groot volumes suur mynafloopwater gevorm word. Hierdie proses benodig suurstof en vog. Suur mynafloopwater kan moontlik beheer word deur 'n situasie te skep waar die toestande in die hope ongunstig is vir die ysteroksiderende bakteriee. Die huidige navorsing het die moontlikheid ondersoek om hierdie bakteriee te inhibeer deur verskillende afvalhoopontwerpe op die proef te stel en sodoende suurvorming in steenkoolmynhope te beperk. Die fisiese en chemies kondisies, suurvorming en populasies van vier verskillende bakterie-groepe wat dalk by suurvorming betrokke is, is vanaf September 1993 tot Julie 1995 bestudeer in die buitenste lae van tien verskillend gekonstrueerde loodsskaalafvalhope by die Kilbarchan myn naby Newcastle in KwaZulu-Natal. Afvalhoopbedekkings bestaande uit 'n 30-cm of 70-cm Estcourt grond met 'n lae permeabiliteit bedek met'n 70-cm of 30-cm laag van meer deurlaatbare Avalon grond het anaerobe kondisies veroorsaak. Ongekompakteerde 30-cm en gekompakteerde 50-cm Avalon grondlae het egter nie bestendige anaerobe kondisies in die hope veroorsaak nie. Die onbedekte hope het aerobics gebly met slegs effense dalings van suurstofkonsentrasies gedurende en na swaar reens. Geisoleerde monsters uit die steenkoolafval onder die 50-cm Avalon grondlaag het vanaf die begin van die toetsperiode tekens van suurvorming getoon. Die onbedekte steenkoolafval en die van die sel met 'n 30-cm Avalon grondlaag het met verloop van tyd al hoe meer suur geword. Die ysteroksiderende bakterie-populasies van die T. ferrooxidans tipe het geblyk om in die onbedekte en Avalon grondbedekte hope wat tekens van suurvorming getoon het hoer te wees as in die hope wat met 'n 1-m laag Avalon grond of Avalon en Estcourt grond bedek is en geen tekens van suurvorming getoon het nie. Ysteroksiderende bakteriepopulasies van die Metallogenium tipe, nieasidofiele en asidofiele tiosulfaatoksiderende populasies was oor die algemeen laag in die steenkoolafvalhope. Vyf van die grondlae wat alma! 1 m dik was het dus geblyk om effektief te wees in die bekamping van die infiltrasie van suurstof na die onderliggende steenkoolafval in die loodskaalhope. Dit lyk asof daardie lae die ysteroksiderende populasies betrokke by suurvorming onderdruk het. Die 0.5-m grondbedekking het egter nie so 'n sterk onderdrukkende effek op die suurstofinfiltrasie of die bakteriepopulasie gehad nie. Na aanleiding van hierdie resultate blyk dit dat steenkoolafvalhope in Suid-Afrika met minstens 0.5 tot 1..0 m grond bedek moet word om effektief die probleem van suur mynafloopwater te bekamp.

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40

Modinger, Heinrich. "Micro-organisms involved in iron oxidation and acid mine drainage formation in KwaZulu-Natal and their control by soil covers on coal waste dumps". Thesis, Stellenbosch : Stellenbosch University, 1998. http://hdl.handle.net/10019.1/55926.

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Abstract (sommario):

Thesis (MSc)--Stellenbosch University, 1998.
One copy microfiche.
ENGLISH ABSTRACT: The biologically catalysed oxidation of pyrite in the outer layers of coal waste dumps leads to the formation of acid mine drainage. The oxidation of pyrite to ferric iron and sulphate is a complex process involving various abiotic and biologically catalysed reactions. Pyrite is abiotically oxidized by ferric iron, with the formation of thiosulphate and ferrous iron. Thiosulphate decomposes to form various inorganic sulphur compounds. Bacterial catalysis of pyrite oxidation is achieved by iron-oxidizing bacteria oxidizing ferrous iron to ferric iron. Bacteria that oxidize sulphur compounds assist the catalysis by oxidizing thiosulphate and its decomposition products. Heterotrophic organisms may play a role by consuming organic substances inhibitory to the lithotrophic bacteria. Abiotic ecological factors, acid formation and populations of iron-oxidizing bacterial groups were studied in 10 differently constructed pilot scale coal waste dumps, as the second phase of a study which started in September 1993. Gas samples were withdrawn weekly from coal waste through permanently buried stainless steel probes, for analysis in the field using a portable oxygen/carbon dioxide meter. Samples of coal waste were extracted by auger for analysis of moisture, pH and microbial populations. The analyses of oxygen and pH can be recommended for the routine monitoring of rehabilitated waste dumps. Covers of Avalon soil 0.3 or 0.5 m thick, were not adequate to prevent acidification. Coal waste covered with 0.7 m compacted beneath 0.3 m uncompacted Avalon soil, showed a slow pH decline, but reached approximately pH 3 in 1997. Covers of compacted Estcourt soil beneath tmcompacted Avalon soil to a cover depth of 1 m were effective in preventing acidification and generally kept the coal waste anaerobic. However, all covers developed cracks during drought conditions in 1995, allowing aeration. Low pH of some samples from these dumps during 1995/1996 may have indicated the start of acidification. Bacteria oxidizing high concentrations of ferrous iron and considered to be Thiobacillus ferrooxidans, were monitored routinely, but may not have been the dominant iron-oxidizer, as population counts using media with a lower ferrous iron concentration were higher. The majority of the latter organisms could also not oxidize sulphur, hence were not T. ferrooxidans. The populations of the high ferrous iron-oxidizing bacteria were affected by pH, tending to be high in acidified and low in non-acidified coal waste. Investigations of microbial populations forming iron-oxidizing consortia in enrichment cultures from coal waste and acid drainage samples showed the presence of T. ferrooxidans, the heterotrophic bacterial genus Acidiphilium, fungi of the genus Penicillium, unidentified filamentous fungi, including Cladophialophora-like morphological types, and a yeast of the genus Dipodascus. In interaction studies, the Penicillium isolate had an inhibitory effect on T. ferrooxidans (subjected to organic compound stress), but the Cladophialophora-like fungi reduced inhibition by organics. Fungi have not previously been studied in detail as components of iron-oxidizing consortia, but the bacterial isolations agree with those elsewhere, indicating that appropriate conclusions from acid mine drainage research in other parts of the world can be applied in KwaZulu-Natal.
AFRIKAANSE OPSOMMING: Die biologies gekataliseerde oksidasie van piriet in die buitenste lae van steenkoolafvalhope lei tot die vorming van suur mynafloopwater. Die oksidasie van piriet tot ferri-yster en sulfaat is 'n komplekse proses wat abiotiese en biologies gekataliseerde reaksies insluit. Piriet word abioties deur ferri-yster geoksideer, met die vrystelling van tiosulfaat en ferro-yster. Tiosulfaat verval om verskeie anorganiese swawelverbindings te vorm. Bakteriese katalise van pirietoksidasie word deur ysteroksiderende bakteriee wat ferro-yster na ferri-yster oksideer, bewerkstellig. Bakteriee wat swawelverbindings oksideer maak 'n bydrae tot die katalise deur tiosulfaat en vervalprodukte daarvan te oksideer. Heterotrofe organismes mag ook 'n rol speel deur organiese verbindings wat die litotrofe bakteriee mag inhibeer, te verbruik. Abiotiese ekologiese faktore, suurvorming en bevolkings ysteroksiderende bakteriee is in 10 verskillend gekonstrueerde loodsskaal steenkoolafvalhope bestudeer, as die tweede fase van 'n studie wat in September 1993 begin het. Gas monsters is weekliks uit die steenkoolafval onttrek deur vlekvrye staal peilers wat permanent daarin begrawe is, en met behulp van 'n draagbare suurstoflkoolstofdioksiedanaliseerder in die veld ontleed. Monsters van die steenkoolafval is met behulp van 'n kleiboor vir die analise van vog, pH en mikrobepopulasies geneem. Die analise van suurstof en pH kan aanbeveel word vir die roetiene monitering van gerehabiliteerde afvalhope. Bedekkings van 0.3 of 0.5 m Avalongrond was nie voldoende om suurvorming te verhoed nie. Steenkoolafval wat met 0.7 m gekompakteerde en 0.3 m ongekompakteerde Avalongrond bedek is, het 'n stadige pH-daling getoon, maar het in 1997 ongeveer pH 3 bereik. Bedekkings van gekompakteerde Estcourtgrond onder ongekompakteerde A valongrond met 'n totale dikte van 1 m, was effektief in die voorkoming van suurvorming. Hulle het oor die algemeen die steenkoolafval anaerobies gehou, maar aile bedekings het tydens die droogte in 1995 krake ontwikkel, wat suurstof laat binnedring het. 'n Lae pH gedurende 1995/1996 by sommige monsters uit hierdie hope mag die begin van suurvorming aangedui het. Bakteriee wat hoe konsentrasies ferro-yster oksideer en wat as Thiobacillus ferrooxidans beskou is, was moontlik nie die dominante ysteroksideerder nie, aangesien bevolkingstellings waar 'n medium met 'n laer konsentrasie ferro-yster gebruik is, hoer bevolkings getoon het. Die meerderheid van laasgenoemde organismes kon ook nie swawel benut nie en dus nie T. ferrooxidans was nie. Die bevolkings van die hoe ferro-ysteroksiderende bakteriee is deur pH beInvloed, met 'n geneigdheid tot hoe bevolkings in suur en lae bevolkings in minder suur steenkoolafval. Ondersoeke na die rnilcrobebevollcings wat in ysteroksiderende konsortia in verryldngslculture vanaf steenkoolafval- en suur mynafloopwatermonsters voorgekom het, het die teenwoordigheid van 7'. ferrooxidans, die heterotrofe balcteriegenus Acidiphilium, fungi van die genus Penicillium, ongeIdentifiseerde fungi, insluitend Cladophialophora-agtige tipes en 'n gis van die genus Dipodascus aangetoon. By interaksiestudies het die Penicillium-isolaat 'n inhiberende effek op T ferrooxidans (onderworpe aan organiese verbindingstres) gehad, maar die Cladophialophora-agtige fungi het die inhibisie deur organiese verbindings verminder. Fungi is nog the in detail as komponente van ysteroksiderende konsortia bestudeer the, maar die isolasies van bakteried stem saam met die van elders wat aandui dat toepaslike gevolgtreldcings ten opsigte van suur mynafloopwatemavorsing vanaf ander dele van die wereld ook in KwaZulu-Natal toegepas kan word.

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41

Yung, Matthew Maurice. "Oxidation catalysis in environmental applications nitric oxide and carbon monoxide oxidation for the reduction of combustion emissions and purification of hydrogen streams /". Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187128442.

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42

Paixão, Filho Jorge Luiz da 1984. "Aplicação de lodo de lagoa facultativa em roseira". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258485.

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Orientadores: Adriano Luiz Tonetti, Bruno Coraucci Filho
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo.
Made available in DSpace on 2018-08-20T18:04:49Z (GMT). No. of bitstreams: 1 PaixaoFilho_JorgeLuizda_M.pdf: 2379245 bytes, checksum: 00497843fd17605c51498a78155246f6 (MD5) Previous issue date: 2012
Resumo: A geração de lodo de esgoto (LE) é uma característica intrínseca do tratamento das águas residuárias por processos biológicos. Aliado a isso, o aumento do número de estações de tratamento de esgoto tem demandado soluções para a disposição econômica e ambientalmente segura para o lodo gerado. Um sistema amplamente utilizado no Brasil para o tratamento de esgoto desde a década de 80 são as lagoas de estabilização, no entanto ao longo desses anos o lodo gerado nesse sistema não tem recebido atenção, devido a baixa produção per capita e seu longo tempo de residência na lagoa. Uma opção com grande destaque no cenário nacional para sua disposição é a aplicação do lodo na agricultura como fonte de nutrientes em culturas com elevada necessidade de fertilizantes, tal como a roseira. Portanto, o objetivo desse trabalho foi estudar a aplicação do lodo da lagoa facultativa primária da cidade de Coronel Macedo (Estado de São Paulo) na cultura de roseiras variedade 'Carola', avaliando os efeitos sobre o desenvolvimento da planta. O experimento foi instalado em uma área experimental do Departamento de Saneamento e Ambiente da Faculdade de Engenharia Civil, Arquitetura e Urbanismo (UNICAMP), no município de Campinas-SP. As roseiras foram plantadas em baldes de 20 L, sendo o lodo incorporado na camada superficial do solo. Os parâmetros avaliados foram: a massa seca das raízes (MSR), a massa seca da parte aérea (MSPA), volume das raízes, área das folhas (AF) e concentração de nitrogênio no tecido foliar (NTF). Também foi estudada a quantidade de nitrato lixiviado e a fração de mineralização (FM) do lodo. A quantidade de lodo aplicada foi baseada na necessidade de nitrogênio da cultura, de acordo com o cálculo proposto pela resolução CONAMA 375/06. Os tratamentos foram: T1 - tratamento testemunha absoluta, T2 - 12 Mg ha-1 de lodo em base seca (BS), T3 - 24 Mg ha-1 de lodo BS (dose calculada), T4 - 36 Mg ha-1 lodo BS e T5 - adubação mineral (100 kg N ha-1). O delineamento experimental foi em blocos casualisados, com seis repetições. Foi verificado que o aumento da dose de lodo aplicado na roseira aumentou a MSR, MSPA, AF e o NTF. O maior crescimento da roseira (MSR+MSPA) aconteceu nos tratamentos T4 e T5, com 93 e 104 g planta-1, respectivamente. Houve um incremento na MSR na aplicação de LE na dose recomendada pela norma, de 14,00 e 34,00 g planta-1 para T1 e T3 respectivamente. Na primeira análise a maior AF e NTF foi no T4 com 14,66 cm2 e 21,43 g kg-1. A lixiviação de nitrato foi de aproximadamente 5% do nitrogênio total aplicado para os tratamentos com lodo (T2, T3 e T4) e de 10% na adubação mineral (T5). A FM do lodo da lagoa facultativa, determinada em incubação aeróbia, foi de 40%, valor acima do sugerido para lodo digerido anaerobiamente pela norma brasileira (FM = 20 %). Deste modo, a aplicação de lodo de esgoto na cultura da roseira proporcionou aumento nos valores dos parâmetros observados e para o cálculo da aplicação do lodo da lagoa em estudo o FM deve ser de 40%
Abstract: The sewage sludge (SS) generation is an intrinsic characteristic of the treatment of wastewater by biological processes. Allied to this, the increasing number of wastewater treatment plants has demanded solutions for the economical and environmentally safe disposal for the SS. A widely system used in Brazil for the wastewater treatment since years 80's is the stabilization ponds, however over the years the sludge generated in this system has not received attention owing the low production per capita and to long residence time in the pond. An option with great emphasis on the national stage for their disposal is the application in agriculture as a source of nutrients in crops with high demand for fertilizers, such as the rose bush. Therefore, the aim of this work was to study the application of sludge from the facultative lagoon from city Coronel Macedo (São Paulo State, Brazil) in cultured rose variety 'Carola', assessing the effects on plant development. The experiment was installed in an experimental area of Department of Sanitation and Environment, Faculty of Civil Engineering, Architecture and Urbanism (UNICAMP) in Campinas-SP. The roses were planted in 20L buckets, the sludge being applied subsurface. The parameters evaluated were: root dry matter (RDM), the shoot dry mass (SDM), root volume, leaf area (LA) and nitrogen concentration in leaf tissue (NLT). Also studied was the amount of nitrate leaching and the mineralization fraction (MF) of the sludge. The amount of sludge was applied based on the need for nitrogen of the culture, according to the method proposed by CONAMA 375/06. The treatments were: T1 - absolute control treatment, T2 - 12 Mg ha-1 sludge on a dry basis (DB), T3 - 24 Mg ha-1 sludge DB (calculated dose), T4 - 36 Mg ha-1 sludge DB and T5 - mineral fertilizer (100 kg N ha-1). The experimental design was randomized blocks with six replications. It was found that increasing the dose of sludge applied to the rose bush increased the RDM, SDM, LA and NLT. The largest growth of the rose (RDM + SDM) occurred in treatments T4 and T5, with 93 and 104 g plant-1, respectively. There was an increase in the RDM in the application of SS in the dose recommended by the standard of 14.00 and 34.00 g plant-1 for T1 and T3, respectively. In the first analysis the largest LA and NLT was 14.66 cm2 and 21.43 g kg-1 in T4. Nitrate leaching was about 5% of total nitrogen applied to the sludge treatments (T2, T3 and T4) and 10% in mineral fertilizer (T5). MF the sewage sludge of facultative lagoon, determined by aerobic incubation, was 40% above the value suggested for anaerobically digested sludge by Brazilian standard (MF = 20%). Thus, the application of sewage sludge in the culture of rose provided to increase the observed parameters and for calculating the application of sewage sludge of facultative lagoons in agriculture MF should be 40%
Mestrado
Saneamento e Ambiente
Mestre em Engenharia Civil

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43

Sherman, Jessica F. "Soil Iron, Aluminum, and Phosphorus Dynamics in Response to Long-Term Nitrogen and Sulfur Additions at the Bear Brook Watershed in Maine". Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/ShermanJF2005.pdf.

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44

Truini, Margot. "The use of Hydrochemistry to Identify Potential Processes Operating in the Saddle Mountains Basalt Aquifer and the use of the Nitrate-nitrogen Isotope to Distinguish between Potential Sources of Nitrate to the Shallow Alluvial Aquifer in the Lower Umatilla Basin, Oregon". PDXScholar, 1996. https://pdxscholar.library.pdx.edu/open_access_etds/5206.

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Nitrate concentration in excess of national drinking-water standards (10 mg/l) are present in the shallow alluvial aquifer and Saddle Mountains Basalt (SMB) aquifer in the Lower Umatilla Basin, Oregon. To determine sources responsible for elevated nitrate concentrations in the SMB aquifer mass-balance and reaction-path models (NETPATH and PHREEQE) were used to understand observed geochemical trends. Nitrate-nitrogen isotopes were used to distinguish potential nitrate sources in the shallow alluvial aquifer. NETPATH-validated simple water/rock reactions in the SMB aquifers in Irrigon (dissolving glass, precipitating smectite, dissolving or precipitating calcite, and cation exchange) using constituents (calcium, magnesium, sodium and carbon). Diversity of composition for the shallow alluvial water and limited number of wells available made obtaining a mass balanced solution for the SMB aquifer near Boardman impossible. Irrigon basalt groundwaters were consistent with the PHREEQE models prediction of natural hydrochemical trends, where Boardman basalt groundwaters plotted consistently with impacted alluvial groundwater. Nitrogen-isotopic values of nitrate (o 15NNo3) were measured in the shallow alluvial groundwater from 17 wells in 4 land-use settings, 3 lysimeter samples and 1 surface water effluent sample. The landuse setting and corresponding average ranges for nitrate concentrations (as N) and 015NNo3 values for wells near: commercial fertilizer-irrigated fields range from 25-87 mg/l, +3.5 to +4.6 per mil; explosive washout lagoons ranged from 10-18 mg/l, +4.6 to +4.9 per mil; potato waste water application ranged from 6.4-17.8 mg/l, +4.4 to +35 per mil; past confined animal feeding operations (CAFO) ranged from 16-56 mg/l, +4.9 to 10.4 per mil; lysimeters 5.4-39.9 mg/l, +9.1 to +21.9 per mil; surface water effluent ranged from 60-61 mg/l, +3.5 to 6.5 per mil; and varying landuse ranged from 9.3-19.5 mg/l, +2.7 to +7.1 per mil. Commercial fertilizer 0 15NNo3 signatures are consistent for this source. Explosive 015NNa3 values are consistent with an atmospheric signature. CAFO o15NNo3 signatures probably result from mixing between currently applied commercial fertilizer and past CAFO's. High 015NNo3 Signatures (+22 to +35 per mil) imply denitrification. Potato waste water and varying land-use 015NNo3 signatures indicate probable mixing of nitratenitrogen sources in the groundwater.

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45

Hernandez-Romo, Adriana. "An analysis of nitrate contaminated water in Cherry Valley". CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2726.

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The purpose of this study was to evaluate the level of nitrate contamination in the water in Cherry Valley. It examines the theory that human effluent is the source of the nitrate and evaluates the role of politics in the nitrate issue.

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46

Lalor, Briony Maree. "An assessment of the recovery of the microbial community in jarrah forest soils after bauxite mining and prescription burning". University of Western Australia. School of Earth and Geographical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2010.0037.

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[Truncated abstract] Recovery of soil nutrients, microbial populations and carbon (C) and nitrogen (N) cycling processes are critical to the success of rehabilitation following major ecosystem disturbance. Bauxite mining represents a major ecosystem disturbance to the jarrah (Eucalyptus marginata) forest in the south-west of Western Australia. Mining has created a mosaic of mined areas in various stages of succession surrounded by non-mined forest areas. Initial site preparations within rehabilitation areas such as contour ripping alter soil structure (creation of mound and furrows) and over time also influence the distribution of vegetation and litter. Current performance criteria developed by industry, government and other stakeholders have determined that before post-bauxite mined areas of jarrah forest can be integrated back into normal forest management practises they should be functional and demonstrate resilience to normal forest disturbances such as fire. Furthermore, resilience should be of a manner comparable to non-mined analogue forest sites. Currently little is known of the resilience of microbial communities and C and N cycling in rehabilitation sites to normal forest disturbances such as prescription burning. As such, before rehabilitated jarrah forests can be successfully integrated into broad scale forest management regimes, a more thorough knowledge of the potential impacts of burning practises on the soil microbial community and C and N cycling processes in these systems is required. ... While there are similar rates of C and N cycling the underlying microbial community structure was distinctly different; implying a high degree of functional redundancy with respect to C and N cycling. Differences in the C and N cycling and structure of the microbial communities were likely to be due to differences in soil environmental conditions (i.e. soil alkalinity/acidity, soil moisture) and C substrate availability which influence the physiological status of the microbial community and in turn are related to successional age of the forests. Results also suggest that the measurement of CLPP can be a useful approach for assessment of changes in the functional ability of microbial communities. However, the interpretation of how well these rehabilitation forests have recovered heterotrophic abilities was greatly affected by the methodological approach used (e.g. MicroRespTM or Degens and Harris, 1997). Importantly, results from Chapter 4 and 5 suggested that the effects of a moderate prescription fire on C and N processes, CLPP and microbial community structure of 18 year old rehabilitation forests are likely to be short-lived (< 2 years). Furthermore, the effects of the moderate spring prescription fire were not large enough to decouple C and N cycling processes over the short-term (< 1 years) which suggests that by 18 years of age rehabilitation forests demonstrate comparable functional resilience to a moderate prescription burn.

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47

Pattinson, Woodrow Jules. "An investigation into local air quality throughout two residential communities bisected by major highways in South Auckland, New Zealand". Thesis, University of Canterbury. Environmental Science, 2014. http://hdl.handle.net/10092/10002.

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Population exposure to traffic pollution is a rapidly developing, multi-disciplinary scientific field. While the link between long-term exposure and respiratory issues is well-established, there are probable links to a number of more serious health effects, which are still not fully understood. In the interests of protecting human health, it is prudent that we take a cautionary approach and actively seek to reduce exposure levels, especially in the home environment where people spend a significant portion of their time. In many large cities, a substantial number of homes are situated on land immediately adjacent to busy freeways and other heavily-trafficked roads. Characterising exposures of local residents is incredibly challenging but necessary for advancing epidemiological understandings. While existing studies are plentiful, the results are mixed and generally not transferable to other urban areas due to the localised nature of the built environment and meteorological influences. This thesis aimed to employ a variety of methods to develop a holistic understanding of the influence of traffic emissions on near-highway residents' exposure in two communities of South Auckland, New Zealand, where Annual Average Daily Traffic (AADT) is as high as 122,000 vehicles. First, ultrafine particles (UFPs), nitrogen oxides (NOx), carbon monoxide (CO) and particulate matter ≤ 10 μm (PM₁₀) were continuously monitored using a series of fixed stations at different distances from the highways, over several months during the winters of 2010 and 2011. Emissions modelling output (based on traffic composition), was used within a dispersion model to compare modelled concentrations with monitored levels. In addition, community census meshblock units were mapped by level of social deprivation in order to assess potential inequities in highway emissions exposure. The second layer of local air quality investigation involved using a bicycle platform to systematically measure concentrations of UFPs, CO and PM₁₀ using the entire street-grid network throughout each community. This was done forty times - five times at four times of day (07:00, 12:00, 17:00 and 22:00), for each study area, with the aim of mapping the diurnal fluctuation of microspatial variation in concentrations. Using global positioning system (GPS) data and geographical information system (GIS) software, spatially-resolved pollutant levels were pooled by time of day and the median values mapped, providing a visualisation of the spatial extent of the influence of emissions from the highways compared to minor roads. The third layer involved using data from multiple ambient monitors, both within the local areas and around the city, to simulate fifty-four residents' personal exposure for the month of June, 2010. This required collecting timeactivity information which was carried out by door-to-door surveying. The time-activity data were transformed into microenvironment and activity codes reflecting residents movements across a typical week, which were then run through the US-EPA's Air Pollution Exposure Model (APEX). APEX is a probabilistic population exposure model for which the user sets numerous microenvironmental parameters such as Air Exchange Rates (AERs) and infiltration factors, which are used in combination with air pollutant concentrations, meteorological, and geospatial data, to calculate individuals' exposures. Simulated exposure outputs were grouped by residents' occupations and their home addresses were artificially placed at varying distances from the highways. The effects of residential proximity to the highway, occupation, work destination and commute distance were explored using a Generalised Linear Model (GLM). Surveyed residents were also asked a series of Likert-type, ordered response questions relating to their perceptions and understandings of the potential impacts of living near a significant emissions source. Their response scores were explored as a function of proximity to the highway using multivariate linear regression. This formed the final layer of this investigation into air quality throughout these South Auckland communities of Otahuhu and Mangere Bridge. Results show that concentrations of primary traffic pollutants (UFPs, NOx, CO) are elevated by 41 - 64% within the roadside corridor compared to setback distances approximately 150 m away and that the spatial extent of UFPs can reach up to 650 m downwind early in the morning and late in the evening. Further, social deprivation mapping revealed that 100% of all census meshblocks within 150 m either side of both highways are at the extreme end of the deprivation index (NZDep levels 8 - 10). Simulations for residents dispersed across the community of Otahuhu estimated daily NOx and CO exposure would increase by 32 and 37% (p<0.001) if they lived immediately downwind of the highway. If they were to shift 100 m further downwind, daily exposure would decline by 56 - 70% (p<0.001). The difference in individuals' exposure levels by occupation varied across the same distance by a factor of eight (p<0.05), with unemployed or retired persons the most exposed due to having more free time to spend outdoors at home (recreation, gardening, etc.). Those working in ventilated offices were the least exposed, even though ambient concentrations - likely due to a strong urban street canyon effect - were higher than the nearest highway monitor (5 m downwind) by 25 - 30% for NOx and CO, respectively. Inverse linear relationships were identified for distance from highway and measures of concern for health impacts, as well as for noise (p<0.05). Positive linear relationships were identified for distance from highway and ratings of both outdoor and indoor air quality (p<0.05). Measures of level of income had no conclusive statistically significant effect on perceptions (p>0.05). The main findings within this thesis demonstrate that those living within the highway corridor are disproportionately exposed to elevated long-term average concentrations of toxic air pollutants which may impact on physical health. While the socioeconomic characteristics could also heighten susceptibility to potential health impacts in these areas, certain activity patterns can help mitigate exposure. This thesis has also shown that there may be quantifiable psychological benefits of a separation buffer of at least 100 m alongside major highways. These results enhance a very limited knowledge base on the impacts of near-roadway pollution in New Zealand. Furthermore, the results lend additional support to the international literature which is working to reduce residential exposures and population exposure disparities through better policies and improved environmental planning. Where possible, the placement of sensitive population groups within highway corridors, e.g. retirement homes, social housing complexes, schools and childcare centres, should be avoided.

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48

Brittain, Jeffrey Thomas. "The Response of Zooplankton Communities in Montane Lakes of Different Fish Stocking Histories to Atmospheric Nitrogen Deposition Simulations". PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2394.

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Freshwater ecosystems are subject to a wide variety of stressors, which can have complex interactions and result in ecological surprises. Non-native fish introductions have drastically reduced the number of naturally fishless lakes and have resulted in cascading food web repercussions in aquatic and terrestrial habitats. Additional anthropogenic influences that result from increases in global airborne emissions also threaten wildlife habitat. Atmospheric nitrogen deposition has been recognized as an anthropogenic contributor to acidification and eutrophication of wilderness ecosystems. Planktonic communities have shown declines in response to predation and shifts in composition as a result of nutrient inputs and acidification, both of which are potential fates of nitrogen deposition. This study identified the response of zooplankton communities from two lakes (fish present vs. absent) in Mount Rainier National Park to manipulations simulating an episodic disturbance event in mesocosms. The experiment used a 2 x 2 factorial design with acid and nitrogen treatments. Treatments resulted in significantly elevated nitrogen and decreased pH conditions from control mesocosms over 42 days, indicating that the treatment effects were achieved. Results indicate that zooplankton communities from lakes with different food web structure respond differently to the singular effects of acid and nitrogen addition. Surprisingly, the interaction of the two stressors was related to increases in community metrics (e.g., abundance, biomass, body size, richness, and Shannon-Weiner diversity) for both lake types. This work can aid management decisions as agencies look to restore more aquatic montane habitats to their historic fishless states, and assess their abilities to recover and afford resistance to atmospheric pollution.

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49

Šiuipys, Nerijus. "Priežemio ozono koncentracijos sklaida Kauno mieste ir jos ryšys su meteorologinėmis sąlygomis". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090810_112539-45872.

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Viena didžiausių problemų, atsirandančių dėl oro taršos miestų ore, yra tarša, sukelta fotocheminių oksidantų, tarp jų, ir priežemio ozono. Darbo tikslas: nustatyti priežemio ozono koncentracijos sklaidą Kauno mieste ir jos ryšį su meteorologinėmis sąlygomis. Tyrimai buvo vykdomi 2006 - 2009 metais. Darbo objektas - Kauno miestas. Visoje miesto teritorijoje priežemio ozono koncentracija buvo matuota 10 skirtingų matavimo vietų. Ozono koncentracijai nustatyti buvo naudotas „Aeroqual 300 Series” ozono matuoklis. Priežemio ozono koncentracija buvo matuota vidudienį nuo 12 iki 14 ir vakare nuo 17 iki 19 valandos. Kiekvienoje vietoje buvo atlikta nuo 4 - 6 matavimų, kiekvieno sezono metu. Tyrimų metu nustatyta, kad priežemio ozono koncentracijos pasiskirstymas kiekvieno sezono metu yra skirtingas. Didžiausia vidutinė sezoninė priežemio ozono koncentracija buvo nustatyta pavasario - vasaros sezonų metu (72 g/m3), o mažiausia žiemos sezono metu (7 g/m3). 2009 m. pavasario sezono metu Vileikos g., prie GMF nustatyta didžiausia vienkartinė priežemio ozono koncentracija (128 g/m3). Buvo vertintas priežemio ozono koncentracijos ryšys su meteorologinėmis sąlygomis ir azoto oksidų (NOx) koncentracija. Gauti rezultatai parodė, statistiškai reikšmingą teigiamą ryšį tarp ozono koncentracijos ir temperatūros (r = 0,73; p = 0,00) ir NO2 koncentracijos (r = 0,48; p = 0,03). Tai rodo, kad didėjant temperatūrai ir NO2 koncentracijai, didėja ir priežemio ozono koncentracija. Tarp priežemio... [toliau žr. visą tekstą]
One of the major problems resulting from air pollution of the urban area, is the pollution caused by photochemical oxidants, among their, ground level ozone. The aim of this work was to assess distribution of ground level ozone concentration in Kaunas and its relationship to meteorological situation. Measurements was carried out in 2006 - 2009. Object of work has been selected Kaunas city. Throughout the city area ground level ozone concentration was measured by a sampling scheme for the 10 different measurement points. For determinate of ground level ozone concentration, we used ozone quality monitor „Aeroqual 300 Series“. Ground level ozone concentration was measured at midday from 12 to 14 and in the evening from 17 to 19 hours. Each site was carried out from 4 - 6 measurements. Study rezults revealed, that ground level ozone concentration distribution of each season is different. The maximum average ozone concentration was found in spring - summer season (72 g/m3), and the lowest in winter season (7 g/m3). The higher ground level ozone concentration episode (128 g/m3) was stated in spring season in 2009 year. Relationship between ground level ozone concentration and meteorological situations and nitrogen oxides (NOx) concentration was evaluated. The results showed statistically significant positive relationship between ozone concentration and temperature (r = 0,73; p = 0,00) and NO2 concentration (r = 0,48; p = 0,03). Between ground level ozone concentration and wind... [to full text]

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50

Simpson, Lisa G. "Impact of long-term manure application on soil macronutrient levels in Southern Alberta". Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Geography, c2010, 2010. http://hdl.handle.net/10133/3098.

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The role of manure applications on soil nutrient dynamics in years after manure applications cease has not been extensively studied. An investigation of two long-term manure trials in the Battersea Drain watershed in southern Alberta was undertaken in 2004 to determine changes in soil nutrient status three years after the initial study was completed. The investigation of the nutrient status of an intensive livestock operation was another component of the study. There was a significant decrease in levels of soil nitrogen, phosphorus and potassium in the plots that received manure application rates over 60 Mg ha-1. The nutrient status of the farm showed a net export of nitrogen and an accumulation of phosphorus and potassium in the soil. Recommendations for alternate methods for handling manure were presented.
x, 120 leaves : ill (some col.), col. maps ; 29 cm

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Tesi sul tema "Nitrogen oxides Environmental aspects"

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