Flow and chemical characteristics of the St. Johns River at Jacksonville, Florida

This report will be of substantial value to water managers in developing the St. Johns River as a multiple resource. Evaluation of the capacity of the river to accept pollutants without adversely affecting other uses requires detailed data of flow and chemical characteristics and an understanding of how they interact. (66 page document)

Mechanical and Chemical Control of Smooth Cordgrass in Waillapa Bay, Washington

We evaluated four methods to control smooth cordgrass (Spartina alterniflora Loisel), hereafter spartina, in Willapa Bay, Washington: mowing, mowing plus herbicide combination, herbicide only for clones, and aerial application of herbicide for meadows. (PDF has 7 pages.)

Seasonal Changes in Chemical Composition of Eurasion Watermilfoil (Myriophyllum spicatum L.) and Water Temperature at Two Sites in northern California: implications for Herbivory

We compared seasonal changes in Eurasian watermilfoil (Myriophyllum spicatum L.) characteristics and water temperature for a shallow poind in Davis, CA, and the Truckee River, near Tahoe City, CA. Tissue C and N were 15% lower in plants from the Truckee River than in plants from the Davis pond. Seasonal fluctuations in tissue N were also different. Mean phenolic acid content of Truckee River palnts (162yM g-1) was less than those from the shallow pond (195 yM g-1). Phenolic acid content was positively related to tissue C for Truckee River and Davis pond plants and, tissue C:N ratio for Truckee River plants. Mean monthly water temperature (1990 to 1998) for the Truckee River site was less than 20 C. Water temperatures were warmer in August and September at this site. However, Eurasian watermilfoil collected during these months was characterized by lower levels of tissue N. During a 29-month period beginning January 1994, mean monthly water temperature for the Davis pond exceeded 20 C, only during July to September 1995. Tissue N was generally greater during summer for watermilfoil growing in the pond. These results imply that Eurasian watermilfoil biological control agents may have different developmental rates in these habitats, and thus different impacts on watermilfoil populations.

Chemical Treatment Methods Pilot (CTMP) System for Treatment of Urban Runoff – Phase I. Feasibility and Design

(pdf contains 418 pages)

Phase II Low Intensity Chemical Dosing (LICD): Development of Management Practices

(pdf contains 265 pages)

Chemical Nonequilibrium Effects on Flow Field for Reusable Launch Vehicles

High temperature chemical non-equilibrium phenomena have a great effect on the flow field around a reentry vehicle. A set of three dimensional Navier-Stokes equations have been solved by implicit finite volume NND scheme. Both ideal gas viscous flow and chemical non-equilibrium flow are calculated for a spherical-cone at a small angle of attack. The results of the two flows have been compared and the effect of chemical non-equilibrium has been analyzed. The effect of wall material's properties, such as catalysis and radiation were studied. The results are in good agreement with the referenced paper.

Chemical equilibrium analysis and CFD simulation of coal combustion and NOx formation

A full two-fluid model of reacting gas-particle flows with an algebraic unified second-order moment (AUSM) turbulence-chemistry model is used to simulate Beijing coal combustion and NOx formation. The sub-models are the k-epsilon-kp two-phase turbulence model, the EBU-Arrhenius volatile and CO combustion model, the six-flux radiation model, coal devolatilization model and char combustion model. The blocking effect on NOx formation is discussed. In addition, the chemical equilibrium analysis is used to predict NOx concentration at different temperature. Results of CID simulation and chemical equilibrium analysis show that, optimizing air dynamic parameters can delay the NOx formation and decrease NOx emission, but it is effective only in a restricted range. In order to decrease NOx emission near to zero, the re-burning or other chemical methods must be used.

Studies of physical, chemical, and biological oceanography in the vicinity of the Revilla Gigedo Islands during the “Island Current Survey” of 1957

ENGLISH: The tendency of the tunas, especially the yellowfin (Neothunnus macropterus) to be more abundant in the near vicinity of islands and seamounts, or "banks", than in the surrounding oceanic areas, is well known to commercial fishermen. This has been confirmed by statistical analysis of fishing vessel logbook records, which demonstrates that the catch-per-day's-fishing is, indeed, higher in the near vicinity of these features. It is hypothesized that islands and seamounts cause changes in the physical circulation or the biochemical cycle resulting in greater supplies of food for tunas in their immediate environs. In order to examine this hypothesis, and in order to study possible mechanisms involved, the "Island Current Survey" was undertaken from 8 May to 12 June, 1957, under the joint auspices of the Inter-American Tropical Tuna Commission and the Scripps Institution of Oceanography. Surveys of varying nature and extent were made from M/V Spencer F. Baird near Alijos Rocks, Clarion Island, Shimada Bank and Socorro Island (Figure 1). These studies sought to provide knowledge of the action of islands and seamounts in arresting, stalling or deflecting the mean current past them, in establishing convergence and divergence in the surface flow, in producing vertical motion (mixing and upwelling), and in influencing the primary production and the standing crops of phytoplankton and zooplankton. Each survey is discussed below in detail. Observations made at a front on 10 June will be discussed in another paper. SPANISH: Los pescadores que realizan la pesca comercial conocen muy bien la tendencia de los atunes, en particular del atún aleta amarilla (Neothunnus macropterus), de presentarse en mayor abundancia en las cercanías inmediatas a las islas y cimas submarinas, o "bancos", que en las áreas oceánicas circundantes. Este hecho ha sido confirmado par el análisis estadístico de los registros de los cuadernos de bitácora de las embarcaciones pesqueras, demostrándose que la captura par dias de pesca es, en efecto, más abundante en la inmediata proximidad de tales formaciones. Hipotéticamente se admite que las islas y las cimas submarinas provocan cambios en la circulación física o en el ciclo bioquímico, lo cual se pone de manifiesto a través de un mejor abastecimiento de alimento para los atunes en sus cercanías inmediatas. Con la finalidad de verificar esta hipótesis y de estudiar los mecanismos que ella involucra, se realizó la “Island Current Survey” del 8 de mayo al 12 de junio de 1957, bajo los auspicios de la Comisión Interamericana del Atún Tropical y de la Institución Scripps de Oceanografia. Con el barco Spencer F. Baird se hicieron observaciones de distintas clases y alcances cerca de las Rocas Alijos, la Isla Clarion, el Banco Shimada y la Isla Socorro (Figura 1). Estos estudios tuvieron por objeto adquirir conocimientos sobre la acción que ejercen las islas y cimas submarinas sobre la corriente promedio, ya sea deteniéndola, reduciendo su velocidad o desviando su curso, así como estableciendo convergencia o divergencia en su flujo de superficie, o provocando un movimiento vertical (mezcla y afloramiento) e influyendo en la producción primaria y en las existencias de fitoplancton y zooplancton. Cada operación será tratada a continuación por separado. Las observaciones hechas el dia 10 de junio sobre un frente serán objeto de otra publicación.

Modified Simplified Rate Equation Model of Flowing Chemical Oxygen-Iodine Laser and its Application

A modified simplified rate equation (RE) model of flowing chemical oxygen-iodine laser (COIL), which is adapted to both the condition of homogeneous broadening and inhomogeneous broadening being of importance and the condition of inhomogeneous broadening being predominant, is presented for performance analyses of a COIL. By using the Voigt profile function and the gain-equal-loss approximation, a gain expression has been deduced from the rate equations of upper and lower level laser species. This gain expression is adapted to the conditions of very low gas pressure up to quite high pressure and can deal with the condition of lasing frequency being not equal to the central one of spectral profile. The expressions of output power and extraction efficiency in a flowing COIL can be obtained by solving the coupling equations of the deduced gain expression and the energy equation which expresses the complete transformation of the energy stored in singlet delta state oxygen into laser energy. By using these expressions, the RotoCOIL experiment is simulated, and obtained results agree well with experiment data. Effects of various adjustable parameters on the performances of COIL are also presented.

Destruction of Chemical Agents in a Plasma Reactor with Working Gas of Hydrogen

Numerical Analysis of the Effects of Free-Stream Thermo-Chemical State on the Test Model Flow Field in High-Enthalpy Tunnel

The effects of the free-stream thermo-chemical state on the test model flow field in the high-enthalpy tunnel are studied numerically. The properties of the free-stream, which is in thermo-chemical non-equilibrium, are determined by calculating the nozzle flow field. A free-stream with total enthalpy equal to the real one in the tunnel while in thermo-chemical equilibrium is constructed artificially to simulate the natural atmosphere condition. The flow fields over the test models (blunt cone and Apollo command capsule model) under both the non-equilibrium and the virtual equilibrium free-stream conditions are calculated. By comparing the properties including pressure, temperature, species concentration and radiation distributions of these two types of flow fields, the effects of the non-equilibrium state of the free-stream in the high-enthalpy shock tunnel are analyzed.

An assessment of chemical contaminants in the marine sediments of southwest Puerto Rico

This report summarizes the results of a characterization of chemical contaminants in the sediments in southwest Puerto Rico. The report is part of a project to integrate various analytical specialties to assess linkages between chemical contaminants and the condition of coral reefs. In this phase of the project, over 120 chemical contaminants were analyzed in sediments collected, including a number of organic (e.g., hydrocarbons), inorganic (e.g., metals), and biological (bacterial) compounds/analytes. The report also provides a preliminary analysis of the association between sediment contaminants and coral species richness. Overall, the levels of chemical contaminants in the study area between Guanica Bay and the town of La Parguera were fairly low. At most of the sites sampled, particularly adjacent to the town of La Parguera, concentrations of organic and inorganic contaminants were below the median values from NOAA’s National Status and Trends Program, which monitors the Nation’s coastal and estuarine waters for chemical contaminants. Elevated levels of a number of contaminant classes were seen at the two sites sampled within Guanica Bay. An initial analysis of modeled PAH (hydrocarbon) data and coral species richness (reef building species) indicated a strong negative correlation between the presence of PAHs in the sediments and coral species richness. Additional work is needed to assess possible reasons for this observed pattern. (PDF contains 126 pages).