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Made available in DSpace on 2014-10-09T12:51:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:26Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Two field plots in the Ladner area, one supporting pasture species and the other inter-tilled crops, were irrigated by sprinkler with water containing more than 13,000 parts per million of ocean salts. Eight acre inches of water were applied annually, in three equal applications, the trial being conducted for a period of two to three years. Soil samples, obtained at appropriate intervals during the course of the irrigation trials, were studied in the laboratory to determine the effects of the treatment on their physical and chemical properties. Plant yields were recorded and tissues chemically analysed to reveal alterations, if any, in the uptake of mineral elements. Analyses revealed that, as a result of irrigation, marked increases occurred in respect to salt content of the soil and osmotic pressures in the soil solution. Subsequent dormant-season rains were observed to remove a large portion of the accumulated salt, but sufficient salt residue remained in the cultivated soil after two year's irrigations to affect injuriously the growth of a non-irrigated silage crop. The exchangeable sodium percentage of the soil was increased only slightly in the pasture field, but to a dangerous level in the cultivated field. Exchangeable magnesium was increased and calcium decreased in both soils. The effects on soil calcium are considered to be important, since the soils are already low in available calcium, and a further deficiency of this element for plant growth is therefore threatened. Studies of soil structure revealed no destructive changes which could be definitely ascribed to irrigation with saline water. Calcium uptake by the plants was generally depressed by the treatment, and of the tissues studied, all, with the exception of the grasses, showed accumulation of sodium Pea and silage corn yields were reduced by irrigation, sugar beet yield was unaffected, and pasture grass yield was increased eight-fold. The quality of all crops was impaired by the treatment. The author is convinced that the continued use of this highly saline water, except in very special circumstances, will cause reduced crop yields and lead ultimately to serious and permanent impairment in the physical and chemical properties of the soils. / Land and Food Systems, Faculty of / Graduate

An anodic stripping voltammetric technique was developed for the simultaneous determination of Cu and Pb in seawater. Mercuric ion added to the sample is plated out with the metals of interest onto a highly polished glassy carbon electrode. The thin mercury films obtained by this procedure gave excellent resolution and sensitivity although a non-linear response resulted in the case of Cu, presumably as a result of saturation of the mercury, at concentrations in excess of 4 μg/1. The technique was applied to a short term study of the distribution of Cu and Pb in Indian Arm and Burrard Inlet. Large fluctuations in the concentrations of both metals were observed during the sampling period, July to October, 1972. Although dissolved Pb concentrations were lower than might be expected near a large urban area, there was, nevertheless, an overall enrichment of the subsurface waters of the inlets relative to Georgia Strait by as much as an order of magnitude. Dissolved Cu concentrations were not, however, significantly higher than those reported for other B.C. coastal waters. Although study of metal speciation by the method employed here was limited by the excess of mercuric ions added to the samples and interferences from surface active agents, evidence was obtained indicating that a portion of Cu in some British Columbia coastal seawater samples is complexed with dissolved organic matter. The experimental conditions indicate that these complexes are either inert to displacement by mercuric ions or have a high degree of specificity for Cu. / Science, Faculty of / Chemistry, Department of / Graduate

Seagrass ecosystems are intense carbon sinks, but they can also emit greenhouse gases (GHG), such as carbon dioxide (CO2) and methane (CH4), to the atmosphere. Yet, GHG emissions by seagrasses are not considered when estimating global CH4 production rates by natural sources, although these estimations will help predict future scenarios and potential changes in CH4 emissions. In addition, the effect of warming on GHG emissions by seagrasses has not yet been reported. The present study aims to assess the CO2 and CH4 production rates by vegetated and adjacent bare sediment of a monospecific seagrass meadow (Halophila stipulacea) located in the central Red Sea. We measured CH4 and CO2 fluxes and their isotopic signatures by cavity ringdown spectroscopy on chambers containing vegetated and bare sediment. The fluxes were measured at temperatures from 25 °C (winter seawater temperature) to 37 °C to cover the natural thermal range and future seawater temperatures in the Red Sea. Additional parameters analyzed included changes in the sediment microbial community composition, sediment organic matter, organic carbon, nitrogen, and phosphorus concentration. We detected up to 100-fold higher CH4 (up tp 571.65 µmol CH4 m−2 d−1) and up to six-fold higher CO2 (up to 13,930.18 µmol CO2 m−2 d−1) fluxes in vegetated sediment compared to bare sediment, and an increase in CH4 and CO2 production with increasing temperature. In contrast, CH4 and CO2 production rates decreased in communities that were maintained at 25 °C, while communities that were exposed to prolonged darkness showed a decrease in CH4 and an increase in CO2 production rates. However, only minor changes were seen in the microbial community composition with increasing temperatures. These results show that GHG emissions by seagrasses might be affected by natural temperature extremes and warming due to climate change in the Red Sea. The findings will have critical implications for the estimation of natural GHG sources, especially when predicting future changes in the global CH4 budget.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Microfiche copy available in Archives and Science. / Bibliography : leaves 37-39. / by Gerald J. Needell. / M.S.

Ionic and osmotic homeostasis, and the intricately linked mechanisms of acid-base balance are critical for the survival of fish. To date, the role of the gastrointestinal (GI) tract in these processes has received only limited study, and our knowledge has been gained almost exclusively through studies conducted in fasting animals. The impacts of feeding and digestion, ubiquitous processes in the natural environment, are likely to be significant but have been overlooked. The current thesis addressed these shortfalls in our current understanding. Research focused on the rainbow trout (Oncorhynchus mykiss), a euryhaline species capable of withstanding the opposing challenges of life in seawater (diffusive influx of ions and loss of water) and freshwater (diffusive loss of ions and gain of water), and concentrated on its physiological response to ingestion of a meal of commercial, dry trout food, containing concentrated salts and little water. The net absorption and secretion of ions and water was tracked in each section of the GI tract of the rainbow trout over a detailed time course using an experimental diet that contained a simple inert marker, in the presence of external freshwater or seawater. Additionally, changes in overall blood chemistry were investigated to examine changes in osmotic, ionic and acid-base regulation during digestion. Feeding in freshwater resulted in the loss of endogenous water to the GI tract during digestion. Additionally, the meal provided much needed ions to balance those lost by diffusion; indeed all of the ingested ions were assimilated along the GI tract except for sodium which was absorbed in the stomach, but secreted in the intestine such that overall sodium balance was close to zero. Feeding also created a metabolic base load (an increase in the concentration of base, or HC03- due HCl secretion into the stomach lumen) that alkalinized the blood (i.e. caused a rise in pH), a phenomenon known as an alkaline tide. The base load was subsequently removed from the blood through increasedexcretion of base to the water via the gills. In seawater, the commercial diet again provided an avenue for water loss. This was potentially deleterious to an organism already suffering from diffusive water loss to the environment. Ion absorption from the diet was negligible, except for potassium and calcium, which were readily assimilated. As in freshwater, digestion resulted in an alkaline tide, however the mechanism of acid-base homeostasis differed with the excess base likely being excreted into the intestine. In contrast to freshwater fish, the gills took up additional base from the external environment, prolonging the acid-base disturbance in seawater fish. Overall, feeding was a dynamic process with far reaching systemic physiological effects. The research described highlighted intimate interactions between the processes of feeding and digestion and ion, water and acid-base homeostasis, and elucidated mechanisms that enable fish to inhabit a wide range of environments. / Thesis / Doctor of Philosophy (PhD)

<p> The open water season of Radstock Bay is less than three months long and varies considerably from year to year. The break-up and ablation sequence of the bay is regular and systematic, commencing with a period of snow melt and run off and continuing until the dramatic evacuation of the ice. This evacuation is dependent on the ice coverage of Lancaster Sound. The ice foot, a feature found often on arctic beaches was found to be larger in areas of more shallow sloping beaches. A sediment size analysis revealed a trend of diminuation of grain size from S. to N. reflecting net sediment transport in that direction. The two major geomorphic events of the 1971 open water, were two storms, both of which had winds from the S.E. that generated 1.0 meter waves which moved sediment from S. to N. The importance of a small pack of ice in the nearshore zone in inhibiting wave action was noted during one of these events. The freeze-up sequence progressed slowly after the advent of sub-freezing temperatures until the temperature of the seawater reached its freezing point, whereupon the rapid covering of the bay with ice ensued.</p> / Thesis / Master of Science (MSc)

Water desalination has the potential to alleviate a significant part of the world’s thirst, with a majority of desalinated water capacity coming from seawater reverse osmosis (SWRO). However, SWRO membrane systems suffer from the loss of performance due to biofouling leading to economic costs. There is no control or preventive strategy for SWRO biofouling and current industry practices recommend chemical treatments to restore membrane performance. Chemical cleaning results in high economic costs due to chemical acquisition, storage, transportation, long plant downtimes and ultimately shorter membrane lifetime and early replacement; in addition to the environmental impact associated with disposing of chemicals. Therefore, there is a need for novel effective green cleaning strategies for SWRO to meet the increasing demand for desalinated water while taking care of the environment. Micronanobubbles (MNBs) consist of small gas cavities formed in aqueous solutions. This study evaluates the efficiency of both air-filled micronanobubbles (AMNBs) and CO2 nucleated MNBs as: i) curative cleaning-in-place (CIP) treatments and ii) preventive daily treatments for biofouling over long-term studies. Experiments were performed using the membrane fouling simulator (MFS) under conditions that are representative of SWRO membrane systems. Pressure drop was implemented as the main biofilm growth monitoring parameter as used by standard industry practices. Curative studies showed that both MNBs CIP treatments had high cleaning efficiencies of 49-56% pressure drop recovery. MNBs pressure drop recovery values were close to the conventional chemical cleaning (NaOH/HCl) at 51% and were significantly higher than the hydraulic flush (HF) physical cleaning control at 24%. The pressure drop recovery results were supported by the optical coherence tomography (OCT) images before and after CIP and biomass autopsy results. Similarly, preventive MNBs daily treatments showed a significant delay in the system’s performance decline. This delay was 5.1 days for the CO2 MNBs experiments, 4 days for the AMNBs, and only 0.6 days for the hydraulic flushing treatments compared to the control. Compared to the control the duration of the operation was doubled in time before the cleaning criteria was met. OCT images confirmed biofilm growth delay with lower biomass occurrence.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Includes bibliographical references. / M.S.