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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Remote sensing chlorophyll-a in the Strait of Georgia

Komick, Nicholas 17 December 2007 (has links)
The main objective of this thesis was to evaluate the use of Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua imagery to estimate chlorophyll-a (chl) concentrations in the surface waters of the Strait of Georgia, located off the southwest coast of Canada. To meet this objective two components were addressed: (1) evaluate chl algorithms using ship-based radiometric and biophysical measurements, (2) evaluate atmospheric correction methods in conjunction with chl algorithms using MODIS Aqua imagery. In Chapter 2, biophysical and above-water reflectance measurements collected in 2006 were used to evaluate the OC3M, standard Garver-Siegel-Maritorena version~1 (GSM01), and a modified version of the GSM01 algorithms for estimating chl concentrations in the Strait. The Strait was generally classified as a case 2 water body, transitioning from chromophoric dissolved organic matter (CDOM) dominant in the central region to possibly particulate dominant in the Fraser River plume region. From these biophysical measurements, results showed that the OC3M algorithm was somewhat effective (r^2 = 0.552) outside the most turbid areas of the Fraser River plume. However, a systematic overestimation of lower chl concentrations was found, which may have been related to the higher CDOM absorption observed throughout the Strait. The standard GSM01 algorithm had moderately good agreement with measured CDOM absorption (r^2 = 0.584) and total suspended solids (TSS) concentrations (r^2 = 0.866), but was ineffective at estimating chl concentrations. Localized characterization of the CDOM absorption, through a hyperbolic CDOM model, improved the modified GSM01 results by providing better agreement with measured CDOM absorption (r^2 = 0.620) and TSS concentrations (r^2 = 0.935). By limiting the GSM01 algorithm to regions with lower combined CDOM and non-algal particulate absorption, the statistical relationship between measured and estimated chl improved (r^2 = 0.690). The further re-interpretation of phytoplankton absorption from the modified GSM01 algorithm with a two-component phytoplankton model resulted in a chl relationship with an r^2 = 0.702 and a linear slope closer to one. However, due to the nature of the GSM01 algorithm, its effectiveness is dependent the accurate characterization of the absorption and backscattering of the optically significant water constituents, which is not always available. Furthermore, the GSM01 algorithm effectiveness is contingent upon the accurate atmospheric correction of the shorter blue wavelengths within satellite imagery. Using unattended fluorometric chl measurements, different atmospheric correction approaches in conjunction with the standard OC3M chl algorithm and modified GSM01 algorithm from Chapter 2 were evaluated in Chapter 3. Atmospheric correction methods that were evaluated included: the standard near infrared (NIR) correction, a shortwave infrared (SWIR) correction, and an adapted version of the correction developed at the Management Unit of the North Sea Mathematical Models (MUMM). The NIR correction with the OC3M algorithm was statistically significant with an adjusted r^2 = 0.759 outside the most turbid portions of the Strait, but had a relatively large RMSE of 0.523, was limited to chl < 21 mg m^-3, and only estimated concentrations for 63% of the pixels. Effectiveness of the SWIR correction was limited with the OC3M algorithm because of the low percentage of estimated chl concentrations (21% of the pixels) and a lower adjusted r^2 = 0.572 outside the more turbid portion of the Strait. The adapted MUMM correction was the most effective, using the spatially averaged aerosol properties from the SWIR correction with the fixed NIR water-reflectance ratio defined by the MUMM method. The MUMM correction with the OC3M algorithm, when limited to pixels outside the Fraser River influence, had an adjusted r^2 = 0.720 and provided chl estimates for 84% of the pixels. The modified GSM01 algorithm was ineffective with all three atmospheric corrections due to the overcorrection of the 412 nm band. Several possible reasons for this overcorrection were identified, including the presence of absorbing aerosols and absorption from atmospheric nitrogen dioxide. When comparing spatial-temporal patterns in the MUMM corrected OC3M image with chl measurements, general spatial patterns and temporal trends match, with some explainable exceptions. Firstly, turbidity typically found near Fraser River plume makes the OC3M algorithm ineffective. Secondly, under lower aerosol reflectance conditions, the signal-to-noise ratio of the SWIR bands can make the spatial identification of the aerosol properties difficult.
272

An assessment of present and historical (1984-2012) Lake Diefenbaker water clarity and chlorophyll-a concentration using Landsat imagery

2014 December 1900 (has links)
Abstract: The use of earth observing satellites can be an effective supplement or alternative to traditional field sampling. The Landsat series of satellites have been particularity useful in assessing water quality in lakes, oceans, and reservoirs. This study utilized Landsat 5 and 7 imagery to model Secchi disk depth (SDD) and chlorophyll-a concentrations (Chl-a) at Lake Diefenbaker, Saskatchewan. I used data from these Landsat satellites to answer the following questions: First, can models that predict water quality (SDD and Chl-a concentration) be developed for Lake Diefenbaker using Landsat imagery? Second, can these models identify trends that have taken place at the reservoir from 1984-2012? Third, can I determine if ephemeral events like algal blooms or flooding have an effect on the reservoir? Novel models were developed from data collected in 2011 and 2012 that could predict SDD and Chl-a concentrations in the reservoir (linear regression, model I). These models explain less variation than comparable studies, but the loss in explanatory power is made up by their ability to predict data from any Landsat image of the reservoir. My study showed that predicted SDD and Chl-a concentration were positively related, an atypical relationship in freshwater systems. During the archive study period (1984-2012), both mean seasonal SDD and mean seasonal Chl-a have significantly decreased throughout the reservoir (p<0.05, regime-shift analysis). Spatially, the greatest decrease in SDD was closest to the major inflow the SSR, while downstream areas in the reservoir have decreased minimally. There was a decline in Chl-a concentrations that was spatially consistent throughout the reservoir. There was a significant negative relationship between flow rate and both water clarity and Chl-a concentrations (P<0.05, model II linear regression). Algal blooms occurred sporadically throughout the study period. There were blooms in 9% of images analyzed. Blooms typically occurred in the Qu’Appelle arm of the reservoir in the late summer and fall. The water quality data extracted by this study can be useful to many future studies, as historical data is absent for much of the reservoir’s history.
273

Productivity and carbon accumulation potential of transferred biofilms in reclaimed oil sands-affected wetlands

Frederick, Kurt R. 06 1900 (has links)
Biofilms are significant contributors to primary production, nutrient cycling, bio-stabilization and the food web of wetland ecosystems. Photoautotrophic biomass (PB) and primary production (PP) were determined for biofilms exposed to various treatments and materials in wetlands near Fort McMurray. Biofilm additions and oil sands process-affected materials were expected to increase the microbial colonization rates on treated substrates and subsequently PB and PP of biofilms over time as compared to controls and unaffected materials. Biofilms survived the transfers and colonized new substrates immediately. Oil sands process affected materials were found to increase PB and PP throughout the first year. A strong decreasing trend for both PB and PP in treatment microcosms occurred in year two, eventually coalescing with control conditions at a lower equilibrium. Transferred biofilms and treatment materials, therefore, increased overall wetland productivity during the initial stages of wetland development when growing conditions are most limiting. / Land Reclamation and Remediation
274

Dependence of stomatal conductance on leaf chlorophyll concentration and meteorological variables

Matsumoto, Kazuho, Ohta, Takeshi, Tanaka, Takafumi 09 1900 (has links)
No description available.
275

Nutrients and chlorophyll dynamics in Fort Cobb Reservoir

Lakish, Benjamin. January 2007 (has links)
Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 31, 2008) Includes bibliographical references.
276

Photo-protective function of carotenoids in photosynthesis

Amarie, Sergiu Unknown Date (has links) (PDF)
Frankfurt (Main), Univ., Diss., 2009 / Erscheinungsjahr an der Haupttitelstelle: 2008
277

Physiological and molecular studies on silicon-induced cadmium tolerance in rice (Oryza sativa l.)

Nwugo, Chika Charles. January 2008 (has links)
Thesis (Ph. D.)--Miami University, Dept. of Botany, 2008. / Title from second page of PDF document. Includes bibliographical references (p. 115-131).
278

Using band ratio, semi-empirical, curve fitting, and partial least squares (PLS) models to estimate cyanobacterial pigment concentration from hyperspectral reflectance /

Robertson, Anthony Lawrence. January 2009 (has links)
Thesis (M.S.)--Indiana University, 2009. / Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Jeffrey Wilson, Lenore Tedesco, Lin Li. Includes vita. Includes bibliographical references (leaves 92-95).
279

Evaluation of technology aimed to improve nitrogen use efficiency for delayed-flood rice (Oryza sativa L.) production

Satterfield, Jason Morris, January 2009 (has links)
Thesis (M.S.)--Mississippi State University. Department of Plant and Soil Sciences. / Title from title screen. Includes bibliographical references.
280

Single molecule switches and molecular self-assembly low temperature STM investigations and manipulations /

Iancu, Violeta. January 2006 (has links)
Thesis (Ph.D.)--Ohio University, August, 2006. / Title from PDF t.p. Includes bibliographical references.

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