994 resultados para Nutrient pollution of water.


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A study was conducted to investigate the survival of five Pseudomonas strains resistant to antibiotics in different types of water. The selected Pseudomonas strains were designated as strain P1 (CT-29), strain P2 (CT-25), strain P3 (CT-36), strain P4 (CT-20) and strain P5 (CT-27) which were only recovered from farmed fishes. Six types of water viz., distilled water, saline water, tap water, deionized water, pond water and river water were used. Among these experimental waters, river water was found to be the most suitable for long-term survival of these strains. Deionized water did not support survival of all these Pseudomonas strains. Pond water, tap water and distilled water were moderately suitable for strain P1 and strain P4. Saline water was also found to be highly suitable for long-term survival in case of the strain P3 and moderately suitable for normal survival of strain P2 and strain P5.

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Water beetle larvae and pupae were collected from the lotic biotopes in localities of the southern part of Ceylon. The species are described and findings are related to previous investigations. The following families were represented: Dytiscidae, Gyrinidae, Hydrophilidae, Helodidae, Dascillidae (Eubrianacinae), Dryopidae and Lampyridae.

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Tullow Oil plc is to launch an onshore Early Production System (EPS) of oil drilling rated at 4,000 barrels of oil per day by 2009. The location of the EPS is in the Kaiso-Tonya area of Block 2 Oil Exploration Zone along Lake Albert within the Albertine graben. Tullow Oil plc contracted Environmental Resources Management (ERM) Southern Africa (Pty) Ltd in conjunction with Environmental Assessment Consult Limited (EACL) to undertake an Environmental Impact Assessment (EIA) for pre-construction and operation of the proposed EPS. ERM in association with EACL requested National Fisheries Resources Research Institute (NaFIRRI) to conduct a baseline survey of water quality and invertebrates in River Hohwa. This study was requested as part of an earlier baseline survey conducted at the Kaiso-Ngassa spit oil exploration area in Block 2. It was conducted at five selected sites (Fig. 1 & Table 1) within the Hohwa River basin in the Kaiso-Tonya Exploration Area 2. The study was pertinent because the targeted oil wells for EPS are upstream this river which drains the Kaiso-Ngassa valley into Ngassa lagoon.

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Centrifuge tests were carried out to determine the effect of 5 different water-soluble chemicals on a thin consolidated disc of clay. The evolution of changes in the clay permeability with time was investigated and other structural changes due to chemical attack were monitored. The findings presented here demonstrate that the permeability of the clay appear to be generally related to the polarity of the chemicals and the dielectric constant, with the exception of Butanol. In the case of Butanol at low flow rate and low stress level, the action of the chemical caused the clay to crack, with a consequent large increase in flow.

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In the current study, the effects of polar solvents on tissue volume and mechanical properties are considered. Area shrinkage measurements are conducted for mineralized bone tissue samples soaked in polar solvents. Area shrinkage is used to calculate approximate linear and volume shrinkage. Results are compared with viscoelastic mechanical parameters for bone in the same solvents (as measured previously) and with both shrinkage measurements and mechanical data for nonmineralized tissues, as taken from the existing literature. As expected, the shrinkage of mineralized tissues is minimal when compared with shrinkage of nonmineralized tissues immersed in the same polar solvents. The mechanical changes in bone are also substantially less than in nonmineralized tissues. The largest stiffness values are found in shrunken bone samples (immersed in acetone and ethanol). The mineral phase in bone thus resists tissue shrinkage that would otherwise occur in the pure soft tissue phase. © 2007 Materials Research Society.