960 resultados para Light water reactors
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This is the report on the Fisheries Aspects of North West Water Authority Schemes to Increase Water Abstraction in West Cumbria by the Egremont and District Anglers’ Association. Existing river pollution and water abstraction in the Ennerdale Lake-River Ehen system is shown to have caused a major deterioration in the conditions in the Ehen fishery. This is reflected by the fact that catches of salmon, sea trout and smelts on the Ehen have all fallen to roughly 6% of the 1965 level; wich is far worse than the deterioration shown in salmon catches for S. W. Cumberland as a whole. Recommendations are made, in the light of proposals by North West Water Authority to increase water abstraction in West Cumbria, to prevent further deterioration in the Ehen fishery in the short term and to improve the situation in the longer term. It contains sections on pollution, water abstraction and fisheries background, flow statistics for and discussion of high water-droughts on the River Ehen, effects of droughts on Tidal Water and a discussion of N.W.W.A. Paper entitled `Water Resources in West Cumbria’ in the light of conditions on the River Ehen.
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This project provides a framework for developing the capabilities of using satellite and related oceanographic and climatological data to improve environmental monitoring and characterization of physical, biological, and water quality parameters in the National Marine Sanctuaries (NMS). The project sought to: 1) assemble satellite imagery datasets in order to extract spatially explicit time series information on temperature, chlorophyll, and light availability for the Cordell Bank, Gulf of the Farallones, and Monterey Bay National Marine Sanctuaries. 2) perform preliminary analyses with these data in order to identify seasonal, annual, inter-annual, and event-driven patterns.
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This report describes the creation and assessment of benthic habitat maps for shallow-water (<30m) marine environments of the Guánica/Parguera and Finca Belvedere Natural Reserve in southwest Puerto Rico. The objective was to provide spatially-explicit information on the habitat types, biological cover and live coral cover of the region’s coral reef ecosystem. These fine-scale habitat maps, generated by interpretation of 2010 satellite imagery, provide an update to NOAA’s previous digital maps of the U.S. Caribbean (Kendall et al., 2001) for these areas. Updated shallow-water benthic habitat maps for the Guánica/Parguera region are timely in light of ongoing restoration efforts in the Guánica Bay watershed. The bay is served directly by one river, the Rio Loco, which flows intermittently and more frequently during the rainy season. The watershed has gone through a series of manipulations and alterations in past decades, mainly associated with agricultural practices, including irrigation systems, in the upper watershed. The Guánica Lagoon, previously situated to the north of the bay, was historically the largest freshwater lagoon in Puerto Rico and served as a natural filter and sediment sink prior to the discharge of the Rio Loco into the Bay. Following alterations by the Southwest Water Project in the 1950s, the Lagoon’s adjacent wetland system was ditched and drained; no longer filtering and trapping sediment from the Rio Loco. Land use in the Guánica Bay/Rio Loco watershed has also gone through several changes (CWP, 2008). Similar to much of Puerto Rico, the area was largely deforested for sugar cane cultivation in the 1800s, although reforestation of some areas occurred following the cessation of sugar cane production (Warne et al., 2005). The northern area of the watershed is generally mountainous and is characterized by a mix of forested and agricultural lands, particularly coffee plantations. Closer to the coast, the Lajas Valley Agricultural Reserve extends north of Guánica Bay to the southwest corner of the island. The land use practices and watershed changes outlined above have resulted in large amounts of sediment being distributed in the Rio Loco river valley (CWP, 2008). Storm events and seasonal flooding also transport large amounts of sediment to the coastal waters. The threats of upstream watershed practices to coral reefs and the nearshore marine environment have been gaining recognition. Guánica Bay, and the adjacent marine waters, has been identified as a “management priority area” by NOAA’s Coral Reef Conservation Program (CRCP, 2012). In a recent Guánica Bay watershed management plan, several critical issues were outlined in regards to land-based sources of pollution (LBSP; CWP, 2008). These include: upland erosion from coffee agriculture, filling of reservoirs with sediment, in-stream channel erosion, loss of historical Guánica lagoon, legacy contaminants and sewage treatment (CWP, 2008). The plan recommended several management actions that could be taken to reduce impacts of LBSP, which form the basis of Guánica watershed restoration efforts.
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We investigated the migration and behavior of young Pacific Bluefin tuna (Thunnus orientalis) using archival tags. The archival tag measures environmental variables, records them in its memory, and estimates daily geographical locations based on measured light levels. Of 166 archival tags implanted in Pacific bluefin tuna that were released at the northeastern end of the East China Sea from 1995 to 1997, 30 tags were recovered, including one from a fish that migrated across the Pacific. This article describes swimming depth, ambient water temperature, and feeding frequency of young Pacific bluefin tuna based on retrieved data. Tag performance, effect of the tag on the fish, and horizontal movements of the species are described in another paper. Young Pacific bluefin tuna swim mainly in the mixed layer, usually near the sea surface, and swim in deeper water in daytime than at nighttime. They also exhibit a pattern of depth changes, corresponding to sunrise and sunset, apparently to avoid a specific low light level. The archival tags recorded temperature changes in viscera that appear to be caused by feeding, and those changes indicate that young Pacific bluefin tuna commonly feed at dawn and in the daytime, but rarely at dusk or at night. Water temperature restricts their distribution, as indicated by changes in their vertical distribution with the seasonal change in depth of the thermocline and by the fact that their horizontal distribution is in most cases confined to water in the temperature range of 14−20°C.
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The liver, heart and muscle tissues of Rohu, (Labeo rohita, Hamilton) were examined for their ubiquinone (UQ) and tocopherol contents. These three tissues contained respectively 11.60, 3.94 and 0.19 mg of ubiquinone and 10.16, 5.32 and 3.58 mg of tocopherol per 100 g. The 4% (V/V) of diethyl ether (EE) in light petroleum ether (PE) fractions of all three tissues on paper chromatographic separation gave spots having the same Rf value as standard ubiquinone-50 (UQ 10). Both the 4% and 6% (V/V) diethyl ether in light petroleum ether fraction of liver, heart and muscle tissues gave a single spot with the same Rf value as α – tocopherol.
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This ICSF Exchange Programme held in Manila is an offshoot of the Bangkok Conference on “Global Fisheries Trends and Future of Fishworkers” held on January 22–27, 1990. One of the issues raised in that conference was about the operation of Taiwanese fishing vessels outside its territorial waters and the impact of such operations on small fishermen from the countries concerned. The presence of a Taiwanese fishworker as well as an NGO supporter contributed to an enlightening discussion as the former shed light on the sad plight of Taiwanese fishworkers who are the victims of such structural problems. This meaningful exchange between groups of fishermen, particularly Taiwanese and Filipinos, resulted in the plan of the Taiwanese delegation to have some Taiwanese fishermen visit the Philippines and immerse in fishing communities.
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Influence of two different forms of nitrogen on growth and physiological aspects of water-cultured seedlings of Rhizophora apiculata was studied. Of the two forms of nitrogen supplied to the growth medium, ammonium nitrogen was better than nitrate nitrogen by exhibiting increased dry matter production, shoot length, leaf area and also enhanced the contents of carotenoids, chlorophylls and their presence in photosystems and light harvesting protein complex.
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Details are given of the construction of a water sampler for use in aquaculture work. The equipment is 3m long, light and easy to fabricate and operate in aquaculture ponds.
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As the most of the fish resources are known and exploited, protecting their generation is of the greatest importance. Aquaculture is one of the efficient procedures in protecting and reviving fish resources and knowing about the reproductive cycle and gonads development has an important role in approaching this aim. Liza abu belongs to the family Mugilidae that according to its resistance to the environmental condition and its fast growth , can be introduced as a fish with economical value. As there is no scientific data on the reproductive biology of this species , study on the reproductive biology and gonad development is considered as the aim of this research . For this purpose , 360 samples of this species were investigated during the period from February 2007 to January 2008 in Khozestan Province . After studing morphological and histological characteristics of gonad specimen , they were prepared through histological method. Samples were prepared through usual histological method and studied under light microscope. According to the results, the maturity stages of male and female Liza abu were separated to six different successive stages. In ovaries , these stages were as follow : In stage І, the oocytes were small , this stage was observed from July to October . In stage ІІ, considerable growth was observed in the oocytes . This stage was observed from October to January . In stage III, due to vitellogenesis, the maximum growth was observed and three layers of theca, granullosa and follicle cells were visible. This stage was observed during January and February . In stage IV, migration of germinal vesicle was observed and due to hydration of the oocytes , their diameter was increased. The ovaries were yellowish and in maximum size and ovules could be easily observed with naked-eye . This stage was observed in February and March . In stage V, spawning occured. This stage was observed in April . In stage VI, ovaries consisted of immature and atretic oocytes and also empty follicles. This stage was observed in May and June. In testes , these stages were as follow : In stage I , the testes were small in size and contained the spermatogonia which were the only cellular components.This stage was observed in August and September . In stage II (maturing virgin ) , the spermatogonia and the primary spermatocytes were visible. This stage was observed in October . In stage III (developing), intensive spermatogenesis was occured and the primary and the secondary spermatocytes were the most visible cells during this stage .This stage was observed from November to January. In stage IV(developed), cells of all stages of spermatogenesis could be seen but the secondary spermatocytes and spermatids were in large number. This stage was observed from January to March. In stage V , the testes were filled with sperms. This stage was observed in March and April .In stage VI, residual spermatozoa and the spermatogonia were visible in the testes. This stage was observed from May to August. According to cyclic changes in GSI, sexual maturation in breeding begins in January and spawning occurs in April. The ova diameter ranged from 30.75 μ in stage I to 472.19 μ in stage IV. In this study , the sex ratio was 1:2.7, and male and female percentage were 27.02% and 72.98% respectively. This means that females predominate males. In this study absolute fecundity was calculated and changing between 30805.44 to 431247.3 was observed and absolute fecundity was calculated 111275.3 in average.
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Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. The performance achievable by the unity conversion ratio cores of these reactors was compared to an existing supercritical carbon dioxide-cooled (S-CO2) fast reactor design and an uprated version of an existing sodium-cooled fast reactor. All concepts have cores rated at 2400 MWt. The cores of the liquid-cooled reactors are placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchangers (IHXs) coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. The S-CO2 reactor is directly coupled to the S-CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced reactor vessel auxiliary cooling system (RVACS) and a passive secondary auxiliary cooling system (PSACS). The selection of the water-cooled versus air-cooled heat sink for the PSACS as well as the analysis of the probability that the PSACS may fail to complete its mission was performed using risk-informed methodology. In addition to these features, all reactors were designed to be self-controllable. Further, the liquid-cooled reactors utilized common passive decay heat removal systems whereas the S-CO2 uses reliable battery powered blowers for post-LOCA decay heat removal to provide flow in well defined regimes and to accommodate inadvertent bypass flows. The multiple design limits and challenges which constrained the execution of the four fast reactor concepts are elaborated. These include principally neutronics and materials challenges. The neutronic challenges are the large positive coolant reactivity feedback, small fuel temperature coefficient, small effective delayed neutron fraction, large reactivity swing and the transition between different conversion ratio cores. The burnup, temperature and fluence constraints on fuels, cladding and vessel materials are elaborated for three categories of material - materials currently available, available on a relatively short time scale and available only with significant development effort. The selected fuels are the metallic U-TRU-Zr (10% Zr) for unity conversion ratio and TRU-Zr (75% Zr) for zero conversion ratio. The principal selected cladding and vessel materials are HT-9 and A533 or A508, respectively, for current availability, T-91 and 9Cr-1Mo steel for relatively short-term availability and oxide dispersion strengthened ferritic steel (ODS) available only with significant development. © 2009 Elsevier B.V. All rights reserved.
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Potamogeton crispus is a cosmopolitan aquatic species and is widely used as a pioneer species for vegetation restoration of eutrophic lakes. However, many restoration projects applying P. crispus turions have not been successful. Earlier studies focused on effects of light and temperature on turion germination. The purpose of this study was to determine whether sediment anoxia and light interactively affected the turion germination and early growth of P. crispus. Anoxic conditions in the experiment were produced by adding sucrose to the sediment. The germination rate of the turions was 68-73% lower in the highly anoxic condition treatment than in the control. Medium light intensity (10% of natural light at the water surface) was more favorable for germination under slightly anoxic conditions than either low or high light intensity. The growth of newly-formed sprouts was also significantly inhibited by sediment anoxia. Photosynthesis and shoot biomass were reduced under sediment anoxia, whereas total chlorophyll content, root biomass, and soluble protein content were highest in the low anoxic condition treatment. Medium light improved net photosynthesis and biomass production of the sprouts. We conclude that turion germination and sprout growth can be significantly inhibited by sediment anoxia. Medium light intensity may alleviate this inhibition by anoxia, but light has little effect when sediment anoxia is severe. For the purposes of vegetation restoration, more attention should be paid to the role of sediment anoxia, and it is necessary to improve sediment and light conditions for turion germination and early growth of P. crispus in eutrophic lakes. These results will contribute to a more complete understanding of turion germination dynamics of P. crispus and will be useful for future restoration programs.
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Submersed macrophytes in eutrophic lakes often experience high NH4+ concentration and low light availability in the water column. This study found that an NH4+-N concentration of 1 mgL(-1) in the water column apparently caused physiological stress on the macrophyte Potamogeton crispus; L The plants accumulated free amino acids (FAA) and lost soluble carbohydrates (SC) under NH4+ stress. These stressful effects of NH4+ were exacerbated under low light availability. Shading significantly increased NH4+ and FAA contents and dramatically decreased SC and starch contents in the plant shoots. At an NH4+-N concentration of 1 mg L-1 in the water column, neither growth inhibition nor NH4+ accumulation was observed in the plant tissues of P. crispus under normal light availability. The results showed that 1 mg L-1 NH4+-N in the water column was not toxic to P. crispus in a short term. To avoid NH4+ toxicity. active NH4+ transportation out of the cell may cost energy and thus result in a decline of carbohydrate. When NH4+ inescapably accumulates in the plant cell, i.e. under NH4+ Stress and shading, NH4+ is scavenged by FAA synthesis. (c) 2009 Published by Elsevier B.V.
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This work was aimed at the study of some physical properties of two current light-cured dental resin composites, Rok (hybrid) and Ice (nanohydrid). As filler they both contain strontium aluminosilicate particles, however, with different size distribution, 40 nm-2.5 mum for Rok and 10 nm-1 mum for Ice. The resin matrix of Rok consists of UDMA, that of Ice of UDMA, Bis-EMA and TEGDMA. Degree of conversion was determined by FT-IR analysis. The flexural strength and modulus were measured using a three-point bending set-up according to the ISO-4049 specification. Sorption, solubility and volumetric change were measured after storage of composites in water or ethanol/water (75 vol%) for 1 day, 7 or 30 days. Thermogravimetric analysis was performed in air and nitrogen atmosphere from 30 to 700 degrees C. Surface roughness and morphology of the composites was studied by atomic force microscopy (AFM). The degree of conversion was found to be 56.9% for Rok and 61.0% for Ice. The flexural strength of Rok does not significantly differ from that of Ice, while the flexural modulus of Rok is higher than that of Ice. The flexural strengths of Rok and Ice did not show any significant change after immersion in water or ethanol solution for 30 days. The flexural modulus of Rok and Ice did not show any significant change either after immersion in water for 30 days, while it decreased significantly, even after 1 day immersion, in ethanol solution. Ice sorbed a higher amount of water and ethanol solution than Rok and showed a higher volume increase. Thermogravimetric analysis showed that Rok contains about 80 wt% inorganic filler and Ice about 75 wt%.
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The terrestrial blue-green alga (cyanobacterium), Nostoc flagelliforme, was cultured in air at various levels of CO2, light and watering to see their effects on its growth. The alga showed the highest relative growth rate at the conditions of high CO2 (1500 ppm), high light regime (219-414 mu mol m(-2)s(-1)) and twice daily watering, but the lowest rate at the conditions of low light (58-114 mu mol m(-2)s(-1)) and daily twice watering. Increased watering had little effect on growth rate at 350 ppm CO2, but increased by about 70% at 1500ppm CO2 under high light conditions. It was concluded that enriched CO2 could enhance the growth of N. flagelliforme when sufficient light and water was supplied.
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Natural humic water was treated with ultraviolet (UV) light and UV + hydrogen peroxide . The effects on the dissolved organic carbon content (DOC), the UV-absorbance at 254 nm (UV-abs.), the molecular size distribution, pH, and mutagenic activity were monitored, and the identity and concentrations of the most abundant gas chromatographable organic degradation products were determined. The DOC content and the UV-abs. of the water decreased substantially during treatment with. The decreases were dependent on the time of irradiation (UV dose) as well as on the H2O2 dose applied. The humus macromolecules were degraded to smaller fragments during irradiation. At higher UV doses, however, part of the dissolved organic matter (DOM) was found to precipitate, probably as a result of polymerization. Oxalic acid, acetic acid, malonic acid, and n-butanoic acid were the most abundant degradation products detected. These acids were found to account for up to 20% and 80% of the DOM in UV- and waters, respectively. No mutagenic activity was generated by the UV irradiation or the treatment. It is further concluded that the substantial mutagenic activity formed during chlorination of humic waters cannot be decreased by using UV irradiation as a pretreatment step.