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Texas Register, Volume 18, Number 75, Pages 6695-6768, October 1, 1993 (open access)

Texas Register, Volume 18, Number 75, Pages 6695-6768, October 1, 1993

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: October 1, 1993
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
Assembly flow simulation of a radar (open access)

Assembly flow simulation of a radar

A discrete event simulation model has been developed to predict the assembly flow time of a new radar product. The simulation was the key tool employed to identify flow constraints. The radar, production facility, and equipment complement were designed, arranged, and selected to provide the most manufacturable assembly possible. A goal was to reduce the assembly and testing cycle time from twenty-six weeks to six weeks. A computer software simulation package (SLAM II) was utilized as the foundation a for simulating the assembly flow time. FORTRAN subroutines were incorporated into the software to deal with unique flow circumstances that were not accommodated by the software. Detailed information relating to the assembly operations was provided by a team selected from the engineering, manufacturing management, inspection, and production assembly staff. The simulation verified that it would be possible to achieve the cycle time goal of six weeks. Equipment and manpower constraints were identified during the simulation process and adjusted as required to achieve the flow with a given monthly production requirement. The simulation is being maintained as a planning tool to be used to identify constraints in the event that monthly output is increased. ``What-if`` studies have been conducted to identify the …
Date: October 1, 1993
Creator: Rutherford, W. C. & Biggs, P. M.
Object Type: Article
System: The UNT Digital Library
Iterative methods for the WLS state estimation on RISC, vector, and parallel computers (open access)

Iterative methods for the WLS state estimation on RISC, vector, and parallel computers

We investigate the suitability and effectiveness of iterative methods for solving the weighted-least-square (WLS) state estimation problem on RISC, vector, and parallel processors. Several of the most popular iterative methods are tested and evaluated. The best performing preconditioned conjugate gradient (PCG) is very well suited for vector and parallel processing as is demonstrated for the WLS state estimation of the IEEE standard test systems. A new sparse matrix format for the gain matrix improves vector performance of the PCG algorithm and makes it competitive to the direct solver. Internal parallelism in RISC processors, used in current multiprocessor systems, can be taken advantage of in an implementation of this algorithm.
Date: October 1, 1993
Creator: Nieplocha, J. & Carroll, C. C.
Object Type: Article
System: The UNT Digital Library
Enhanced Coherence X-Ray Laser Experiments and Simulations (open access)

Enhanced Coherence X-Ray Laser Experiments and Simulations

Bright, spatially coherent x-ray lasers (XRLs) have applications in areas such as holography, interferometric imaging, and non-linear optics. Nominally, the authors can improve XRL coherence by either increasing the length or by reducing the aperture. Length can be increased by coupling multiple stages of XRLs or by using multilayer optics, but the effective gain length of an XRL is limited by refractive propagation and multilayer damages. The laser aperture is typically limited by the best-focused configuration defined by the driving optical lasers. Design of XRLs produced in exploding foil or slab configuration is further complicated by large spatial gain and n{sub e} inhomogeneities. This paper explores new XRL design that uses the concept of adaptive spatial filtering by geometric shaping to improve the transverse coherence. One example of such shaped XRLs is a bowtie. The authors present here computational and experimental characterization of shaped XRLs during laser plasma expansion by studying their hydrodynamic behaviors, ionization histories, and laser output intensities.
Date: October 1, 1993
Creator: Wan, A. S.; Libby, S. B. & Moreno, J. C.
Object Type: Report
System: The UNT Digital Library
Fast-neutron scattering from vibrational palladium nuclei (open access)

Fast-neutron scattering from vibrational palladium nuclei

Neutron total cross sections of elemental palladium are measured from {approx}0.6--4.5 MeV. These results, combined with others previously reported from this laboratory, provide a detailed knowledge of the neutron total cross sections of palladium from {approx}0.1--20 MeV. Differential neutron elastic-scattering cross sections are measured from {approx}1.5--10 MeV in sufficient energy and angle detail to well define the energy-average behavior. Concurrently, neutron inelastic-scattering cross sections are measured from {approx}1.5--8 MeV. Inelastically-scattered neutron groups are observed corresponding to excitations of: 306 {+-} 14, 411 {+-} 47, {approx}494, 791 {+-} 20, 924 {+-} 20, 1,156 {+-} 24, 1,358 {+-} 35, 1,554 {+-} 47 and 1,706 {+-} 59 keV, with additional tentative groups at 1,938 and 2,059 keV. Particular attention is given to the inelastic excitation of the 2{sup +} yrast states of the even isotopes. This broad data base is examined in the context of optical-statistical and coupled-channels models. The resulting model parameters are consistent with systematic trends in this vibrational mass region previously noted at this laboratory, and provide a suitable vehicle for many applications.
Date: October 1, 1993
Creator: Smith, A. B. & Guenther, P. T.
Object Type: Report
System: The UNT Digital Library
Regeneration of vegetation on wetland crossings for gas pipeline rights-of-way one year after construction (open access)

Regeneration of vegetation on wetland crossings for gas pipeline rights-of-way one year after construction

Four wetland crossings of gas pipeline rights-of-way (ROWs), located in Florida, Michigan, New Jersey, and New York, were surveyed for generation of vegetation roughly one year after pipeline construction was completed. Conventional trench-and-fill construction techniques were employed for all four sites. Estimated areal coverage of each species by vegetative strata within transect plots was recorded for plots on the ROW and in immediately adjacent wetlands undisturbed by construction activities. Relative success of regeneration was measured by percent exposed soil, species diversity, presence of native and introduced species, and hydric characteristics of the vegetation. Variable site factors included separation and replacement of topsoil, final grading of the soil, application of seed and fertilizer, and human disturbance unrelated to construction. Successful regeneration exhibited greater dependency on the first three factors listed.
Date: October 1, 1993
Creator: Shem, L. M.; Zimmerman, R. E.; Zellmer, S. D.; Van Dyke, G. D. & Rastorfer, J. R.
Object Type: Article
System: The UNT Digital Library
A literature review of actinide-carbonate mineral interactions (open access)

A literature review of actinide-carbonate mineral interactions

Chemical retardation of actinides in groundwater systems is a potentially important mechanism for assessing the performance of the Waste Isolation Pilot Plant (WIPP), a facility intended to demonstrate safe disposal of transuranic waste. Rigorous estimation of chemical retardation during transport through the Culebra Dolomite, a water-bearing unit overlying the WIPP, requires a mechanistic understanding of chemical reactions between dissolved elements and mineral surfaces. This report represents a first step toward this goal by examining the literature for pertinent experimental studies of actinide-carbonate interactions. A summary of existing models is given, along with the types of experiments on which these models are based. Articles pertaining to research into actinide interactions with carbonate minerals are summarized. Select articles involving trace element-carbonate mineral interactions are also reviewed and may serve as templates for future research. A bibliography of related articles is included. Americium(III), and its nonradioactive analog neodymium(III), partition strongly from aqueous solutions into carbonate minerals. Recent thermodynamic, kinetic, and surface studies show that Nd is preferentially removed from solution, forming a Nd-Ca carbonate solid solution. Neptunium(V) is rapidly removed from solution by carbonates. Plutonium incorporation into carbonates is complicated by multiple oxidation states. Little research has been done on the radium(H) and …
Date: October 1, 1993
Creator: Stout, D. L. & Carroll, S. A.
Object Type: Report
System: The UNT Digital Library
TORT certification package (open access)

TORT certification package

The TORT code has been certified. TORT is a three-dimensional discrete ordinates transport theory code, than can solve neutron, photon, or coupled neutron/photon problems. The code will be used primarily for shielding and radiation field calculations SRS. As defined in this work, certification dies not imply validation. The code must be validated for a particular type of calculation before it can be used for critical applications.
Date: October 1, 1993
Creator: Frost, R. L.
Object Type: Report
System: The UNT Digital Library
Spatial and temporal variation of the surface temperature and heat flux for saturated pool nucleate boiling at lower heat fluxes (open access)

Spatial and temporal variation of the surface temperature and heat flux for saturated pool nucleate boiling at lower heat fluxes

The spatial and temporal variations of local surface temperature and heat flux for saturated pool nucleate boiling are investigated parametrically using a numerical model. The numerical model consisted of solving the three-dimensional transient heat conduction equation within the heater subjected to nucleate boiling over its upper surface. The surface topography model to distribute the cavities over the boiling surface used a Monte Carlo scheme. All cavities were assumed to be conical in shape. The cavity radii are obtained using an exponential probability density function with a known mean value. Local surface temperatures showed significant spatial and temporal variations, depending upon the surface topography and the heater material and thickness. However, the surface-averaged temperature showed practically no temporal variation. The temporal variations in local temperatures caused the surface-averaged heat flux to vary significantly. The temporal variations in the surface-averaged heat flux were similar for smooth and rough and thick and thin copper and nickel plates. Results indicated that the use of a classical energy balance equation to evaluate the surface heat flux must consider the spatial variation of the temperature. Results also showed that any thermocouple embedded beneath the surface of the heater does not follow the temporal variations at the …
Date: October 1, 1993
Creator: Unal, C. & Pasamehmetoglu, K. O.
Object Type: Article
System: The UNT Digital Library
Solid Waste Projection Model: Database User`s Guide. Version 1.4 (open access)

Solid Waste Projection Model: Database User`s Guide. Version 1.4

The Solid Waste Projection Model (SWPM) system is an analytical tool developed by Pacific Northwest Laboratory (PNL) for Westinghouse Hanford Company (WHC) specifically to address Hanford solid waste management issues. This document is one of a set of documents supporting the SWPM system and providing instructions in the use and maintenance of SWPM components. This manual contains instructions for using Version 1.4 of the SWPM database: system requirements and preparation, entering and maintaining data, and performing routine database functions. This document supports only those operations which are specific to SWPM database menus and functions and does not Provide instruction in the use of Paradox, the database management system in which the SWPM database is established.
Date: October 1, 1993
Creator: Blackburn, C. L.
Object Type: Report
System: The UNT Digital Library
Statistical analysis of inhibitor concentrations for radioactive waste in carbon steel tanks (open access)

Statistical analysis of inhibitor concentrations for radioactive waste in carbon steel tanks

Based on a logistic regression approach, a model was developed using the explanatory variables log([NO{sub 3}{sup {minus}}]), log([NO{sub 2}{sup {minus}}]), and temperature to estimate the probability of pitting in a carbon steel exposed to high-level radioactive waste. Pitting susceptibility data obtained by the two techniques of cyclic potentiodynamic polarization and coupon immersion were separately and jointly analyzed with the model. Similar predictive ability is seen for equations based on both electrochemical and coupon immersion data. Using the theory associated with the determination of confidence intervals for the estimated probability, a methodology was developed to provide a lower bound for the nitrite concentration which inhibits pitting, i.e., which holds the estimated probability of pitting to a reasonably low level of 0.05.
Date: October 1, 1993
Creator: Zapp, P. E. & Edwards, T. B.
Object Type: Article
System: The UNT Digital Library
Electrical resistance tomography of concrete structures (open access)

Electrical resistance tomography of concrete structures

The purpose of this work is to determine the feasibility of using Electrical resistance tomography (ERT) to nondestructively examine the interior of concrete structures such as bridge pillars and roadways. We report the results of experiments wherein ERT is used to image the two concrete specimens in the laboratory. Each specimen is 5 inches square and 12 inches long and contained steel reinforcing rods along its length. Twenty electrodes were placed on each sample and an-image of electrical resistivity distribution was generated from current and voltage measurements. We found that the images show the general location of the reinforcing steel and, what`s more important, delineate the absence of the steel. The method may therefore be useful for determining if such steel has been destroyed by corrosion, however to make it useful, the technique must have better resolution so that individual reinforcing steel units are resolved.
Date: October 1, 1993
Creator: Daily, W.; Ramirez, A.; Binley, A. & Henry-Poulter, S.
Object Type: Article
System: The UNT Digital Library
NIPER/DOE Chemical EOR Workshop. Final report (open access)

NIPER/DOE Chemical EOR Workshop. Final report

A Chemical EOR Workshop was held on June 23--24, 1993 in Houston, Texas. The objectives of this workshop were to evaluate the potential for chemical Enhanced Oil Recovery (EOR) to repower significant quantities of remaining domestic oil, to assess the role of the Department of Energy (DOE) and petroleum industry to achieve this potential, and to assess the research needs in chemical EOR. Fifty-six research engineers and scientists from major oil companies, independent oil companies, academic institutes, research institutes, and DOE attended this workshop. Opening remarks were given by Alex Crawley from DOE Bartlesville Project Office and Thomas E. Burchfield of the National Institute for Petroleum and Energy Research (NIPER). The keynote address was delivered by Donald Juckett, Acting Deputy Assistant Secretary for Gas and Petroleum Technology. Ten papers on the state-of-the-art in chemical EOR technologies and recent field test experience were presented on the first day. Two workshops, one on surfactant/alkali flooding and the other on profile modification/polymer flooding, were held on the second day. It was concluded that chemical EOR has the potential of recovering significant quantities of remaining oil, and it is the only method that has the potential of economically recovering residual oil from reservoirs of …
Date: October 1, 1993
Creator: Gall, B. L.; Llave, F. M. & Tham, Min K.
Object Type: Report
System: The UNT Digital Library
Neutron-induced microstructural alteration of GlidCop{trademark} alloys at 415{degrees}C and high neutron exposure (open access)

Neutron-induced microstructural alteration of GlidCop{trademark} alloys at 415{degrees}C and high neutron exposure

GlidCop{trademark} internally oxidized copper alloys remain the leading candidates for high heat flux applications in fusion reactor. This paper presents the microstructural changes incurred in three GlidCop{trademark} alloys exposed to long term, high temperature neutron irradiation. Irradiation at high temperature produced a microstructure containing a much lower dislocation density than the unirradiated specimens. Although 10--50 nm size triangular oxide particles were observed in areas with a very low number density of particles, spherical oxide particles on the order of 5--7 nm in diameter, thought to be CuAl{sub 2}O{sub 4}, were the predominant morphology. The changes in grain size distribution, dislocation density, and precipitate type and distribution saturate in the range of 34 to 50 dpa, as reflected in the saturation of mechanical properties.
Date: October 1, 1993
Creator: Edwards, D. J.; Garner, F. A.; Newkirk, J. W. & Nadkarni, A.
Object Type: Article
System: The UNT Digital Library
Population Differentiation in Tree-Ring Growth Response of White Fir (Abies Concolor) to Climate: Implications for Predicting Forest Responses to Climate Change (open access)

Population Differentiation in Tree-Ring Growth Response of White Fir (Abies Concolor) to Climate: Implications for Predicting Forest Responses to Climate Change

Forest succession models and correlative models have predicted 200--650 kilometer shifts in the geographic range of temperate forests and forest species as one response to global climate change. Few studies have investigated whether population differences may effect the response of forest species to climate change. This study examines differences in tree-ring growth, and in the phenotypic plasticity of tree-ring growth in 16-year old white fir, Abies concolor, from ten populations grown in four common gardens in the Sierra Nevada of California. For each population, tree-ring growth was modelled as a function of precipitation and degree-day sums. Tree-ring growth under three scenarios of doubled C0{sub 2} climates was estimated.
Date: October 1, 1993
Creator: Jensen, D. B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Plasma confinement theory and transport simulation. Technical progress report, May 1, 1991--April 30, 1994 (open access)

Plasma confinement theory and transport simulation. Technical progress report, May 1, 1991--April 30, 1994

The objectives of the Fusion Research Center Theory Program continue to be: (1) to advance the transport studies of tokamaks, including development and maintenance of the Magnetic Fusion Energy Database; and (2) to provide theoretical interpretation, modeling and equilibrium and stability studies for the TEXT-Upgrade tokamak. Publications and reports and conference presentations for the grant period are listed. Work is described in five basic categories: A. Magnetic Fusion Energy Database; B. Computational Support and Numerical Modeling; C. Support for TEXT-Upgrade and Diagnostics; D. Transport Studies; E. Alfven Waves.
Date: October 1, 1993
Creator: Ross, D. W.
Object Type: Report
System: The UNT Digital Library
MACCS usage at Rocky Flats Plant for consequence analysis of postulated accidents (open access)

MACCS usage at Rocky Flats Plant for consequence analysis of postulated accidents

The MELCOR Accident Consequence Code System (MACCS) has been applied to the radiological consequence assessment of potential accidents from a non-reactor nuclear facility. MACCS has been used in a variety of applications to evaluate radiological dose and health effects to the public from postulated plutonium releases and from postulated criticalities. These applications were conducted to support deterministic and probabilistic accident analyses for safety analyses for safety analysis reports, radiological sabotage studies, and other regulatory requests.
Date: October 1, 1993
Creator: Foppe, T. L. & Peterson, V. L.
Object Type: Article
System: The UNT Digital Library
Air pathway effects of nuclear materials production at the Hanford Site, 1983 to 1992 (open access)

Air pathway effects of nuclear materials production at the Hanford Site, 1983 to 1992

This report describes the air pathway effects of Hanford Site operations from 1983 to 1992 on the local environment by summarizing the air concentrations of selected radionuclides at both onsite and offsite locations, comparing trends in environment concentrations to changing facility emissions, and briefly describing trends in the radiological dose to the hypothetical maximally exposed member of the public. The years 1983 to 1992 represent the last Hanford Site plutonium production campaign, and this report deals mainly with the air pathway effects from the 200 Areas, in which the major contributors to radiological emissions were located. An additional purpose for report was to review the environmental data for a long period of time to provide insight not available in an annual report format. The sampling and analytical systems used by the Surface Environmental Surveillance Project (SESP) to collect air samples during the period of this report were sufficiently sensitive to observe locally elevated concentrations of selected radionuclides near onsite source of emission as well as observing elevated levels, compared to distant locations, of some radionuclides at the down wind perimeter. The US DOE Derived Concentration Guides (DCGs) for airborne radionuclides were not exceeded for any air sample collected during 1983 …
Date: October 1, 1993
Creator: Patton, G. W. & Cooper, A. T.
Object Type: Report
System: The UNT Digital Library
New Thomson scattering Laser Control for DIII-D (open access)

New Thomson scattering Laser Control for DIII-D

A Laser Control system has been built for the DIII-D Scattering Diagnostic. This new system has provided the capability to place the laser probe pulses with one microsecond timing precision throughout the DIII-D shot. The new system fires the eight lasers with a programmable sequence which repeats ever 50 ms. If one wants to probe the plasma at a higher rate to study a fast paced event, the new control circuit can fire all charged lasers in rapid succession (BURST MODE). This burst rate is programmable. The new Laser Control system successfully replaced the previous control scheme which consisted of three VME Motorola 68030 computers (one host under UNIX VME V/68 and two interrupt driven targets under VME Exec. The old system was not successful due to the many VME interrupts needed to service the lasers. The new hardware approach is much more reliable. The old system still controls data acquisition and as a monitoring system since it does not have the burden of controlling the lasers. A brief description of the Thomson Scattering diagnostic will be presented with emphasis in the new upgraded laser firing control system and data acquisition timing control.
Date: October 1, 1993
Creator: Makariou, C. C.; Stockdale, R. E.; Carlstrom, T. N.; Hsieh, C. L. & Bramson, G.
Object Type: Article
System: The UNT Digital Library
Technological and economic potential of poly(lactic acid) and lactic acid derivatives (open access)

Technological and economic potential of poly(lactic acid) and lactic acid derivatives

Lactic acid has been an intermediate-volume specialty chemical (world production {approximately}40,000 tons/yr) used in a wide range of food processing and industrial applications. lactic acid h,as the potential of becoming a very large volume, commodity-chemical intermediate produced from renewable carbohydrates for use as feedstocks for biodegradable polymers, oxygenated chemicals, plant growth regulators, environmentally friendly ``green`` solvents, and specially chemical intermediates. In the past, efficient and economical technologies for the recovery and purification of lactic acid from crude fermentation broths and the conversion of tactic acid to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. The development and deployment of novel separations technologies, such as electrodialysis (ED) with bipolar membranes, extractive distillations integrated with fermentation, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The use of bipolar ED can virtually eliminate the salt or gypsum waste produced in the current lactic acid processes. In this paper, the recent technical advances in tactic and polylactic acid processes are discussed. The economic potential and manufacturing cost estimates of several products and process options are presented. The technical accomplishments at Argonne National Laboratory (ANL) and the future directions of this program …
Date: October 1, 1993
Creator: Datta, R.; Tsai, S. P.; Bonsignore, P.; Moon, S. H. & Frank, J. R.
Object Type: Article
System: The UNT Digital Library
Quarterly report on Defense Nuclear Facilities Safety Board Recommendation 90-7 for the period ending June 30, 1993 (open access)

Quarterly report on Defense Nuclear Facilities Safety Board Recommendation 90-7 for the period ending June 30, 1993

This is the ninth quarterly report on the progress of activities that address safety issues associated with Hanford Site high-level radioactive waste tanks containing ferrocyanide compounds. Milestones completed this quarter include (1) a report on the credibility of hot spots and a recommendation on infrared scans; (2) a document discussing the strength and limitations of proposed moisture monitoring technologies; (3) limited calibration of the neutron probe in simulant-filled drums; (4) a report interpreting data from auger surface samples of ferrocyanide tank 241-BY-104; (5) a document on the effect of possible catalyst, initiator, and diluents on ferrocyanide reactivity; (6) a report on small scale sensitivity tests of ferrocyanide flowsheet simulants; and (7) preparation and shipment of T Plant simulants for calorimetric and dryout tests.
Date: October 1, 1993
Creator: Cash, R. J.; Dukelow, G. T.; Forbes, C. J. & Meacham, J. E.
Object Type: Report
System: The UNT Digital Library
Contaminant resorption during soil washing (open access)

Contaminant resorption during soil washing

To evaluate the applicability of soil washing to a specific site requires some basic research in how contaminants are bound. Much can be learned from sequential extraction methodology based on micronutrient bioavailability studies wherein the soil matrix is chemically dissected to selectively remove particular fixation mechanisms independently. This procedure uses a series of progressively more aggressive solvents to dissolve the principle phases that make up a soil, however, the published studies do not appear to consider the potential for a contaminant released from one type of site to resorb on another site during an extraction. This physical model assumes no ion exchange or adsorption at sites either previously occupied by other ions, or exposed by the dissolution. Therefore, to make engineering use of the sequential extraction data, the release of contamination must be evaluated relative to the effects of resorption. Time release studies were conducted to determine the optimum duration for extraction to maximize complete destruction of the target matrix fraction while minimizing contaminant resorption. Tests with and without a potassium brine present to inhibit cesium resorption indicated extraction efficiency could be enhanced by as much as a factor of ten using the brine.
Date: October 1, 1993
Creator: Gombert, D.
Object Type: Article
System: The UNT Digital Library
Development of methods for evaluating options for improving air quality in Santiago, Chile and its environs. Final report (open access)

Development of methods for evaluating options for improving air quality in Santiago, Chile and its environs. Final report

Santiago, Chile has a serious air pollution problem. Aerosols reach very high levels and ozone exceeds US ambient standards on over 100 days a year. Chileans are very concerned about the poor air quality of Santiago and the effect of emissions from their copper smelters both near Santiago and at other sites. Officials from both the Santiago metropolitan air quality commission (La Comision Especial de Descontaminacion de le Region Metropolitana) and a government owned copper development company (La Empress Nacional de Mineria (ENAMI)) have asked for assistance to deal with the air quality problems in the city and associated with smelter emissions. This report describes the first steps in that effort. Santiago lies in a valley between a small coastal range to the west and the towering Andes to the cast. Air motion is greatly affected by the major topographical features which include the Pacific Ocean, the coastal range, and the Andes. In this first year of work the authors concentrated on gathering information on the meteorology, topography, and air quality of the metropolitan region. They examined two smelter sites and applied models to them to help their understanding and to provide assistance to ENAMI. One smelter, Ventanas, was located …
Date: October 1, 1993
Creator: Williams, M. D. & Brown, M. J.
Object Type: Report
System: The UNT Digital Library
Effect of snails (Elimia clavaeformis) on phosphorus cycling in stream periphyton and leaf detritus communities (open access)

Effect of snails (Elimia clavaeformis) on phosphorus cycling in stream periphyton and leaf detritus communities

In this study, the author examined the effect of grazing on phosphorus cycling in stream periphyton and leaf detritus communities using the snail Elimia clavaeformis. Phosphorus cycling fluxes and turnover rates were measured in a laboratory and in a natural stream, respectively, using radioactive tracer techniques.
Date: October 1, 1993
Creator: Jay, E. A.
Object Type: Thesis or Dissertation
System: The UNT Digital Library