999 resultados para 21-210
Resumo:
The Alliance for Coastal Technologies (ACT) convened a workshop on Evaluating Approaches and Technologies for Monitoring Organic Contaminants in the Aquatic Environment in Ann Arbor, MI on July 21-23, 2006. The primary objectives of this workshop were to: 1) identify the priority management information needs relative to organic contaminant loading; 2) explore the most appropriate approaches to estimating mass loading; and 3) evaluate the current status of the sensor technology. To meet these objectives, a mixture of leading research scientists, resource managers, and industry representatives were brought together for a focused two-day workshop. The workshop featured four plenary talks followed by breakout sessions in which arranged groups of participants where charged to respond to a series of focused discussion questions. At present, there are major concerns about the inadequacies in approaches and technologies for quantifying mass emissions and detection of organic contaminants for protecting municipal water supplies and receiving waters. Managers use estimates of land-based contaminant loadings to rivers, lakes, and oceans to assess relative risk among various contaminant sources, determine compliance with regulatory standards, and define progress in source reduction. However, accurately quantifying contaminant loading remains a major challenge. Loading occurs over a range of hydrologic conditions, requiring measurement technologies that can accommodate a broad range of ambient conditions. In addition, in situ chemical sensors that provide a means for acquiring continuous concentration measurements are still under development, particularly for organic contaminants that typically occur at low concentrations. Better approaches and strategies for estimating contaminant loading, including evaluations of both sampling design and sensor technologies, need to be identified. The following general recommendations were made in an effort to advance future organic contaminant monitoring: 1. Improve the understanding of material balance in aquatic systems and the relationship between potential surrogate measures (e.g., DOC, chlorophyll, particle size distribution) and target constituents. 2. Develop continuous real-time sensors to be used by managers as screening measures and triggers for more intensive monitoring. 3. Pursue surrogate measures and indicators of organic pollutant contamination, such as CDOM, turbidity, or non-equilibrium partitioning. 4. Develop continuous field-deployable sensors for PCBs, PAHs, pyrethroids, and emerging contaminants of concern and develop strategies that couple sampling approaches with tools that incorporate sensor synergy (i.e., measure appropriate surrogates along with the dissolved organics to allow full mass emission estimation).[PDF contains 20 pages]
Resumo:
The co-organized Alliance for Coastal Technologies (ACT) and National Data Buoy Center (NDBC) Workshop "Meteorological Buoy Sensors Workshop" convened in Solomons, Maryland, April 19 to 21,2006, sponsored by the University of Maryland Center for Environmental Science (UMCES) Chesapeake Bay Laboratory (CBL), an ACT partner institution. Participants from various sectors including resource managers and industry representatives collaborated to focus on technologies and sensors that measure the near surface variables of wind speed and direction, barometric pressure, humidity and air temperature. The vendor list was accordingly targeted at companies that produced these types of sensors. The managers represented a cross section of federal, regional and academic marine observing interests from around the country. Workshop discussions focused on the challenges associated with making marine meteorological observations in general and problems that were specific to a particular variable. Discussions also explored methods to mitigate these challenges through the adoption of best practices, improved technologies and increased standardization. Some of the key workshop outcomes and recommendations included: 0cean.US should establish a committee devoted to observations. The committee would have a key role in developing observing standards. The community should adopt the target cost, reliability and performance standards drafted for a typical meteorological package to be used by a regional observing system. A forum should be established to allow users and manufacturers to share best practices for the employment of marine meteorological sensors. The ACT website would host the forum. Federal activities that evaluate meteorological sensors should make their results publicly available. ACT should extend their evaluation process to include meteorological sensors. A follow on workshop should be conducted that covers the observing of meteorological variables not addressed by this workshop. (pdf contains 18 pages)
Resumo:
Auf der 21. Sitzung des Fischkomitees wurden die in den letzten 4 Jahren mit dem Ziel der Vereinfachung überarbeiteten Standardentwürfe für Erzeugnisse abschließend beraten und an die Kommission zur Annahme überwiesen. Die verschiedenen Codes of Practice werden am Beispiel des von einer Arbeitsgruppe revidierten und um HACCP-Prinzipien erweiterten Codes für tiefgefrorene Fischfilets von 7 neu eingesetzten Arbeitsgruppen überarbeitet. Eine Regelung über Richtwerte für Quecksilber in Fischen ist in Aussicht.
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Results of the investigation on certain problems of the nutrition of Leptodora and Bythotrephes in Rybinsk Reservoir (Russia) are reviewed. To clarify the composition of the food of Leptodora and Bythotrephes in this period, experiments were provided on their nutrition by cyclopids and rotifers.
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This translation includes selected passages of a longer paper on Mastigophora and Rhizopoda found in saline lakes Weissovo and Repnoie. The translation focuses on describing taxonomy and morphology of Ochromonas species and Pedinella. Plates and figures of the original paper are not included in the translation.
Resumo:
Resumen (ESPAÑOL) En el presente trabajo se ha tratado de analizar la evolución, tanto del concepto de Desarrollo Sostenible, como de la herramienta Agenda 21 Local, verificando la creciente preocupación que se está extendiendo en la ciudadanía, en las instituciones y en las empresas, así como la irreversibilidad de la mayoría de los resultados alcanzados. En este marco, se han estudiado los casos concretos de la implantación de la Agenda 21 Local en Europa, España, Euskadi y Getxo, por ser este último el municipio en el que resido. Con este estudio, se confirma la hipótesis de que, aunque en la implantación de la Agenda 21 Local se aprecia un esfuerzo realizado notable, queda todavía mucho camino por recorrer en la senda hacia la sostenibilidad.
Resumo:
Pisidium obtusale in the neighbourhood of Borka occurs in deep pools on upland bogs. The majority of water-bodies where this mollusc lives are temporary. Their bottoms are covered with sedges, and sometimes mosses occur. Evidently there is a marked attraction of P. obtusale to places overgrown by willow. In pools remote from scrub or woody vegetation it does not appear. Temporary water-bodies fill up with melt water in the middle or the end of April and finally dry up at the end of July or the beginning of August. Observations on the life cycle of P. obtusale started on 21 April 1966, following on the filling-up of the water-body by melt water. The findings of the study are presented in this paper.
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For many years a dye has been used in the practise of pisciculture and pond management, which is known by the name of malachite green, and is used to combat fungus on fish, fish eggs and external animal parasites on fish. The authors describe the problem of the application of malachite green in pisciculture and undertake special, complementary research.
Resumo:
The rhythm of division of 9 species belonging to different groups of algae were analysed in situ and in the laboratory. The research which developed in different environmental conditions attempted to establish the capacity for multiplication and assimilation of chlorophyll on the part of the algae under study with a view to placing them in a culture. The results obtained showed that the green multicellular algae (eg. Ulothrix) and the blue algae (eg. Lyngbya, Oscillatoria) are able to produce an appreciable quantity of dry matter, just as the unicellular algae. At the same time it arises that amongst the numerous factors of the environment, temperature plays one of the most important roles in the process of multiplication.
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In fresh waters the planktonic Crustacea are represented mainly by the two large groups, the Copepoda and the Cladocera. This study focuses on Holopedium gibberum and examines if the plankton is an indicator of soft-water lakes. H. gibberum is found throughout the northern half of the globe but its distribution is scattered and irregular. The study is based on a literature review and samples taken from water bodies in Norway.
Resumo:
It is known that the larvae of Chironomidae in the first stages of life after leaving the egg case, swim for a long time in a body of water. Positive reaction in light, the capability of directed swimming and passive floating in suspension allow the larvae to temporarily carry out a planktonic way of life. This study describes the behaviour of Chironomus dorsalis larvae after leaving the egg case. The feeding of chironomid larvae in the first stages of development was also described.
Resumo:
Zooplankton was studied in four alpine lakes in Switzerland, France and Italy. The presence the presence of the invertebrate predator Heterocope in three lakes was stated. It is then discussed why in three of these four lakes, the copepod Arctodiaptomus denticornis is present in the absence of Arctodiaptomus bacillifer, and vice versa respectively in the second and first parts of the lacustrine summer.
Resumo:
The two lowest T = 3/2 levels in 21Na have been studied in the 19F(3He, n), 20Ne (p,p) and 20Ne (p,p’) reactions, and their excitation energies, spins, parities and widths have been determined. In a separate investigation, branching ratios were measured for the isospin-nonconserving particle decays of the lowest T = 3/2 levels in 17O and 17F to the ground state and first two excited states of 16O, by studying the 15N(3He,n) 17F*(p) 16O and 18O(3He, α)17O*(n) 16O reactions.
The 19F(3He,n) 21Na reaction was studied at incident energies between 4.2 and 5.9 MeV using a pulsed-beam neutron-time-of-flight spectrometer. Two T = 3/2 levels were identified at excitation energies of 8.99 ± 0.05 MeV (J > ½) and 9.22 ± 0.015 MeV (J π = ½+, Γ ˂ 40 keV). The spins and parities were determined by a comparison of the measured angular distributions with the results of DWBA calculations.
These two levels were also obsesrved as isospin-forbidden resonances in the 20Ne(p,p) and 20Ne(p,p’) reactions. Excitation energies were measured and spins, parities, and widths were determined from a single level dispersion theory analysis. The following results were obtained:
Ex = 8.973 ± 0.007 MeV, J π = 5/2 + or 3/2+, Γ ≤ 1.2 keV,
Γpo = 0.1 ± 0.05 keV; Ex = 9.217 ± 0.007 MeV, Jπ = ½ +,
Γ = 2.3 ± 0.5 keV, Γpo = 1.1 ± 0.3 keV.
Isospin assignments were made on the basis of excitation energies, spins, parities, and widths.
Branching ratios for the isospin-nonconserving proton decays of the 11.20 MeV, T = 3/2 level in 17F were measured by the 15N(3He,n) 17 F*(p) 16O reaction to be 0.088 ± 0.016 to the ground state of 16O and 0.22 ± 0.04 to the unresolved 6.05 and 6.13 MeV levels of 16O. Branching ratios for the neutron decays of the analogous T = 3/2 level, at 11.08 MeV in 17O, were measured by the 16O(3He, α)17O*(n)16O reaction to be 0.91 ± 0.15 to the ground state of 16O and 0.05 ± 0.02 to the unresolved 6.05 and 6.13 MeV states. By comparing the ratios of reduced widths for the mirror decays, the form of the isospin impurity in the T = 3/2 levels is shown to depend on Tz.
Resumo:
PART I
The total cross-section for the reaction 21Ne(α, n)24Mg has been measured in the energy range 1.49 Mev ≤ Ecm ≤ 2.6 Mev. The cross-section factor, S(O), for this reaction has been determined, by means of an optical model calculation, to be in the range 1.52 x 1012 mb-Mev to 2.67 x 1012 mb-Mev, for interaction radii in the range 5.0 fm to 6.6 fm. With S(O) ≈ 2 x 1012 mb-Mev, the reaction 21Ne(α, n)24Mg can produce a large enough neutron flux to be a significant astrophysical source of neutrons.
PART II
The reaction12C(3He, p)14N has been studied over the energy range 12 Mev ≤ Elab ≤ 18 Mev. Angular distributions of the proton groups leading to the lowest seven levels in 14N were obtained.
Distorted wave calculations, based on two-nucleon transfer theory, were performed, and were found to be reliable for obtaining the value of the orbital angular momentum transferred. The present work shows that such calculations do not yield unambiguous values for the spectroscopic factors.