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

The purpose of this study is to provide a description of the repercussions of hydro-dam development upon forestry in southeastern British Columbia. This study develops a systems viewpoint, where selected indicators - timber supply, access and transportation, forest land value, and reservoir clearing - are examined to help place land allocation decisions within a comprehensive framework. First, a timber supply model is developed, in which forest land withdrawal to hydro-dams is scrutinized. The model is then expanded to account for timber supply and demand relationships. Findings reveal that approximately 50,000 hectares of better than average sites were withdrawn from forest land, accounting for a reduction in timber supply of approximately 180,000 cubic meters annually. Second, changes in accessibility and transportation patterns due to hydro-dam projects are identified in terms of timber supply disruption, and strategies followed to re-establish forestry. Mica and Revelstoke dams are examined to show the importance of allocating economic resources to forestry for the maintenance of the activity. Third, forest land is evaluated in following the four methodological steps: (1) outline of a benefit-cost analysis framework, (2) definition of a general approach to evaluation, (3) description of B.C. Hydro's assessment, and (4) recommendations for improvement. The case of the Revelstoke Dam is examined, and it is concluded that resource development scenarios must take into consideration timber supply and demand factors. Fourth, reservoir clearing is described to outline an important aspect of short-term impact, and to express the way by which the Forest Service, B.C. Hydro and forest companies co-ordinated their efforts during this transition phase. The study concludes by suggesting that the impacts may be alleviated by initiating intensive forest management in areas affected by hydro-dam projects. The design of an effective system of timber allocation may also permit maintenance, and possible improvement, of accessibility and transportation patterns. However, the success of these actions depends upon the availability of sufficient funding. Finally, within a broader perspective, it is recommended that integrated resource management, as a control mechanism for land allocation and management, be adopted. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

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The effects of deforestation and biomass burning in tropical dry forests (TDF) remain a little studied phenomenon. We quantified total aboveground biomass (TAGB), carbon and nutrient (N,S,Ca,P,K) loss under two separate fire severity scenarios; one early when the fuels were higher in moisture content, one later when the slash fuels were drier and then compared the loss and the regrowth of the sites. The TAGB and nutrients were measured (1993-1995) after the forest was cut, after a forest slash fire, one year after pasture establishment and, two years after the slash fire, biomass was quantified before and after a pasture fire. The treatments were based upon time from slash to burn. The low severity fires (Baja) were burned 65 days and the higher severity fires (Alta) were burned 95 days after the initial slash of TDF on ��� 3.5 ha near the Chamela Biological Research Station on the Ejido San Mateo, Jalisco, Mexico. As a result of the 1993 slash fire, TAGB declined from 118.2 to 43.6 Mg ha����� (62%) in the Baja treatment and from 134.9 to 26.8 Mg ha����� (80%) in the Alta treatment. Nutrients pools declined 57-88% with ��� 10% higher combustion of the Alta pools. In 1995, after the pasture fires, TAGB declined from 40.3 to 14.8 Mg ha����� (63%) and from 29.0 to 7.6 Mg ha����� (75%) in the Alta treatment and nutrient pools declined 57-88%. Total aboveground biomass loss from 1993-1995 was 103.4 Mg ha����� (87%) in the Baja treatment and 127.3 Mg ha����� (94%) in the Alta treatment. Carbon and nutrient losses ranged from 87-96% over the three-year study. We found little ash retention after fire, no increase in nutrient soil concentrations and, highly volatized nutrients (i.e. Ca and P) were essentially lost due to wind and water erosion on 40 to 60% slopes. Wood decomposition between fires reduced TAGB and nutrient pools by 15% in the Baja treatment and 3% in the Alta treatment. / Graduation date: 2000

The use of municipal refuse (RDF) as fuels has received widespread attention for reason of its energy equivalence and the increasing lack of available landfill sites. The principal obstacle to the construction of combustion facilities is that RDF produces toxic compounds, including heavy metals and such organic compounds as PCDD and PCDF. In this study, the emissions of metal and organic compounds were investigated under oxygen deficient and oxygen surplus conditions for the RDF and such high volume contributors as office papers and magazines. The principal metal emissions of the RDF were Al, Ca, K, Si, and Zn. Magazines significantly contribute B, Mg, Mn, Ti emissions, whereas office papers contributed Ti and Zn emissions. The metal emissions were not significantly different between oxygen deficient and oxygen surplus conditions at a temperature of 750��C. The combustion of RDF produced a full range of PCDFs and PCDFs, the source of which was determined to be RDF, papers, and even untreated wood combustion effluents in the parts-per-billion range. In contrast to metal emissions, emission rates were higher under the oxygen surplus condition than for the oxygen deficient condition and PCDD and PCDF emissions were significant in relation to the chloride contents of fuel, rather than by fuel type as was the case for the large volume contributors. With the exception of Hg, Se, S, Sr, and Pb, the metal emissions were largely derived from the particles in the effluent. / Graduation date: 1993 / Text is slanted on original. Best scan available.

The technological development and application of waste-to-resource strategy is significantly critical and crucial in both environmental and manufacturing industries, via which we do not only provide practical treatments to toxic waste materials but also translate them into usable products. It has been considered as a preferred method which should be applied in future wastewater treatment strategies. In this study, we investigated the process of incorporating cadmium oxide and nickel oxide into ceramic-based materials with the phases of CdAl4O7, and CdFe2O4. Such products are of less harmful effect to the natural environment and can also be of beneficial use with their good mechanical properties identified by nano-indentation. We proved the possibility and provided an opportunity to convert the waste from wastewater treatment process to a new material resource. XRD is preferred for characterizing solid mixtures to determine the relative abundances of crystalline phases during the reaction process. As a result, we can obtain the relative abundance information on the growth of the crystalline products, such as CdAl4O7, and CdFe2O4 according to the change of fabrication temperatures. In that case, the starting reaction temperature and the optimized temperature (at which the completed reaction could be achieved) could be revealed. In Cd-Al system, the starting temperature for CdAl4O7 formation is 900 °C, and the optimized formation temperature is around 1020 °C. On the other hand, for Cd-Fe system, such temperatures are of 700 °C and 850 °C correspondingly. In our research, it is shown that the ceramic-process is an effective strategy to stabilize the waste hazardous metals (cadmium and nickel) by materials such as aluminate, ferrite, and kaolin commonly used in ceramic industry. Through this method, the difficult-to-treat wasted metals would become reusable and applied in building and infrastructure projects. Products containing CdAl4O7, CdFe2O4 and NiAl2O4 have shown higher resistance to acidic leaching, comparing to CdO and NiO used as the starting materials to simulate the waste metal forms discharged from the industrial stream. Furthermore, similar measurements by alkaline attack on the sintered products (NiAl2O4 containing samples) were also studied. Besides the investigation to leaching behavior, the mechanical properties are also measured by nano-indentation in our work. The incorporation of metal waste into the fabrication of ceramic products is valuable due to the preferred stabilization mechanisms of crystal structures and the large volume of ceramic products needed by the construction industry. Furthermore, because the product safety and functionality should not be compromised, a fundamental understanding of the surface properties of metal containing phases should be further established, rather than relying solely on data from regulatory tests on bulk samples. Therefore, the results of this study demonstrate the superior mechanical properties of nickel spinel containing products, comparing to the cristobalite silica matrix, under severe acid attack. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

Self-regulatory Code of Conduct has widely been adopted by international brands to manage CSR issues in apparel and footwear supply chain for the last 2 decades. Increasingly, more apparel and footwear brands started to expand CSR scope to include environmental management in their supply chain. However, only very few international brands have disclosed their efforts on environmental management in their supply chain. This study aims to find out how apparel and footwear brands implement environmental management in their supply chain. Furthermore, what motivates them to carry out environmental management, and lastly, what challenges the industry encounters in carrying out effective environmental management. Primary and secondary data research were carried out in this study. Primary research, in a form of self-administered survey, was conducted for 11 brands and 15 of their respective suppliers. Secondary research was conducted through desktop research to gather additional information from brands, NGOs, academic studies and news. The study revealed environmental management in apparel and footwear supply chain is becoming more important. However, most of the brands’ approaches on environmental management are loose (i.e. lack industry-wide sustainably environmental management strategy), and small in scope (i.e. first tier supplier only). It is suggested apparel and footwear brands should improve effectiveness of environmental management program in their supply chain, by applying different implementation strategies internally, with both brands’ and suppliers’ governments, suppliers as well as their stakeholders. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

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