Thesis (M.S.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis--Ph. D., University of Hong Kong, 1978.

Waterflooding has been used for many decades as a way of recovering oil from petroleum reservoirs. Historically the salinity of the injection water has not been regarded as a key variable in determining the amount of oil recovered. In recent years, however, evidence of increased oil recovery by injection of low salinity water has been observed in laboratories and fields. The technique is getting wider attention in the oil industry because it is more cost-effective than other EOR techniques. The present work demonstrates the synergy of low salinity water flooding and polymer flooding in the laboratory scale. The use of low salinity polymer solution in polymer flooding has significant benefits because considerably lower amount of polymer is required to make the solution of a target viscosity. Low salinity polymer flooding can also increase oil recovery by lowering residual oil saturation and achieve faster oil recovery by improving sweep efficiency. Several coreflood experiments were conducted to study the efficiency of low salinity water flooding and low salinity polymer flooding in mixed-wet Berea sandstone cores. All the core samples were aged with a crude oil at 90oC for 30-60 days before the tests. All the polymer floods were conducted in the tertiary mode. A synthetic formation brine (33,800 ppm) was chosen for high salinity water and a NaCl brine (1,000 ppm) for low salinity water. Medium molecular weight HPAM polymer, FlopaamTM 3330S was used due to the low/moderate permeability of the Berea sandstone cores used in this study. Coreflood tests indicate that injection of low salinity polymer solution reduces residual oil saturation by 5-10% over that of the high salinity waterflood. A part of the residual saturation reduction is due to low salinity and this reduction is achieved in less pore volumes of injection in the presence of polymers. Effluent ion analysis from both low salinity water flooding and low salinity polymer flooding showed a slight increase in divalent cation concentrations after the polymer breakthrough. Cation bridging may play a role in oil wettability and low salinity injection desorbs some of these cations. / text

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This study aimed to address the current status of the United Arab Emirates date palms. The first chapter focused on the development of the date palm sector in the UAE. A huge increase in the date palm number was achieved in the past few decades. In the same time, there are critical issues facing this development, such as water demand, salinity, and Red Palm Weevil. The second chapter is a greenhouse experiment to test the growth of twelve date palm seeds at four NaCl levels, control, 3000, 6000, and 12000 ppm. Optimal growth found at control and 3000 ppm of NaCl. Relative growth rate (RGR), biomass, and NL decreased significantly by increasing salinity; however, no significant differences were observed in the average SGR for any cultivars. Increased NaCl leads to significant decreases in K+, Mg2+, and Ca2+ contents of plants. Na:K ratios were lower in shoots than in roots. Lulu, Fard, Khnaizi, Nabtat Safi, and Razez cultivars showed higher RGR and biomasses whereas Khnaizi, Mesally, and Safri had higher Na:K ratios than other cultivars in the control indicating higher Na+ discriminations from plant parts. The third chapter studied the vegetation change in the eastern region of the UAE. Due to shortage of fresh water resources, the vegetation of the eastern region of the UAE has experienced a series of declines resulting from salinization of groundwater. To assess these changes, field measurements combined with Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) based Soil Adjusted Vegetation Index (SAVI) were analyzed. Images from two dates, 1987 and 2000 were acquired to enable the computation of the greenness anomalies for three sites in the eastern region, Fujairah, Kalba, and Hatta. The results show an overall increase in the agricultural area, associated with a severe decrease in vegetation greenness and health conditions, particularly in the Kalba study area. The SAVI values decreased with increased soil salinity, permitting the identification of salt-affected areas. Potential areas of further research range from studying the effects of tree spacing and understory crops as immediate and potential solutions to maintain productivity and mitigate the salinity problem.

Many species of caridean shrimp are protandrous hermaphrodites, maturing initially as males but developing into females as they age and grow. A unique sexual system was recently discovered in the peppermint shrimp, Lysmata wurdemanni. In this species, individuals are initially male, but become simultaneous functional hermaphrodites over time. As in most caridean shrimp, L. wurdemanni can mate as a male during the intermoult period, but can reproduce through female function for only a short period after moulting. Ecdysis does not occur en masse in this species, and thus the operational sex ratio found in populations of L. wurdemanni is extremely male-biased. Sexual selection theory suggests that these conditions will result in increased competition for access to mates. Evolutionary pressures should therefore have selected for mechanisms that permit individuals to quickly identify and locate potential mating partners. L. wurdemanni were exposed to chemical stimuli collected from recently moulted conspecifics of varying reproductive condition. Test animals were able to distinguish among the different conditions, and physically manipulated only the plastic nozzle used to pump solutions collected from shrimp with ovaries filled with vitellogenic oocytes. It was subsequently hypothesized that methyl farnesoate, a hormone associated with ovarian maturation in crustaceans, might be a key component of sex pheromones used by L. wurdemanni. However, a series of methyl farnesoate concentrations did not elicit responses, indicating this species does not use this hormone alone when determining reproductive condition. Reproductive behaviour in L. wurdemanni was observed to differ both before and after copulation, as well as with increasing population density. Intermoult individuals were more likely to approach, follow and remain in the vicinity of a near-moult shrimp before mating could occur, and under high density conditions. The near-moult shrimp approached conspecifics only under low density conditions, and performed rapid escape behaviours only after copulation had occurred. The unusual occurrence of epibiota upon L. wurdemanni was described, and the location, size and age of barnacles quantified. The effect of salinity upon grooming activities was tested. Results indicated that carapace grooming was depressed at low salinities, and could account for the considerable epibiota found in this region.

Soil salinity is a serious environmental stress threatening productivity of major crops worldwide. Among the various biotic and abiotic strategies that exist, transgenic technologies provide a promising avenue to reduce yield losses in crops under saline environments. Recently, transgenic technology involving the TMT gene encoding thiol methyltransferase enzyme has been suggested as an effective solution for engineering a chloride detoxification capability into a high value crops to improve tolerance against chloride ion toxicity under saline environments. This proposed mechanism, however, results in the emission of methyl chloride (CH3Cl) from plants, which has deleterious effects on stratospheric ozone. This study was performed to examine the relationship between salt tolerance and chloride volatilizing capacity of transgenic plants containing TMT gene as well as to explore the possibility of generating transgenic rice crop containing TMT gene for salinity tolerance. To achieve these objectives, transgenic tobacco plants containing TMT gene were grown in comparison with wild type tobacco plants under three levels of sodium chloride (NaCl) salinity (0, 100 and 200 mM), three levels of soil water content (40%, 60% and 80% of the field capacity) and their tolerance to NaCl and water stress was studied. Plant growth parameters recorded included plant height, number of leaves, leaf area, stem dry weight, leaf dry weight, root dry weight, plant dry biomass and root/shoot ratio. Similarly, both types of plants were exposed to five levels of NaCl concentrations (0, 50, 100, 150 and 200 mM) and three levels of soil water content (40%, 60% and 80% of the field capacity), and the quantity of CH3Cl emitted was recorded. Significant decrease in plants growth parameters of both types of plants were recorded upon exposure to salinity and water stress. Under 100 mM NaCl, however, transgenic plants showed better tolerance to salinity by suffering less reduction in growth parameters compared to wild type plants. Under 200 mM NaCl, growth of both types of plants was completely inhibited. The interactive effects of salinity and water stress were more pronounced in wild type plants than in transgenic plants. Results also showed that all engineered plants acquired an ability to efficiently transform chloride ion to CH3Cl, and the rate of such transformation was higher under greater NaCl and soil water content compared to lower NaCl concentrations and soil water content. In order to explore the possibility of generating a transgenic food crop using TMT gene, a hypothetical transgenic rice crop was grown over 27 million hectares of the saline coastal areas of south and southeast Asia and the possible emission of CH3Cl from such ecosystem was inferred based on the CH3Cl emission data obtained from transgenic tobacco plants. The estimates showed that the possible CH3Cl emission from such ecosystem would be 219.21 Gg which is equivalent to 5.36 % of the global atmospheric emissions of CH3Cl.

Increasing temperatures are expected to cause secondary salinisation in freshwater systems, such as the zooplankton community of Churchill, Manitoba. Salinity is a key environmental factor structuring these communities, thus, increasing salinity should cause these communities to change; however, previous research has shown that they are resilient. In order to ascertain how changing salinity will affect these communities I conducted toxicity tests for five crustacean species, individually and in a community setting. I sampled several pools throughout the season to ascertain the salinity level at which those same species were most abundant in the field. While the species had significantly different field distributions along the salinity gradient, the salinity levels associated with maximum densities did not correlate with the lab tolerances. However, lab tolerances were outside the field salinity range, thus providing an unexpected result. Local interactions appear to be very important in determining final community composition along this salinity gradient. / Northern Scientific Training Program, Northern Research Fund