bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the Use of Community Similarity Techniques As Applied to Phytoplankton Communities
Authors: Reinke DC 
Published: December 2008

Seven community similarity indices were compared using a manipulated data set with known changes and an experimental data set of phytoplankton community data. Community similarities were calculated based on (1) strict number of individuals per species and (2) corrected for species size with an estimate of total biomass. The similarity techniques used in this study were heavily affected by the abundant species, and changes in the minor taxa were frequently undetectable. Two of the seven statistics were previously unpublished modifications of the Percent Similarity method of Whittaker [1], which were specifically modified to enhance the sensitivity to changes in low frequency species and proportional changes.
While complex numerical techniques are commonplace in ecological literature, there is no generally accepted mathematical definition of community similarity. Ideally community comparison techniques should be sensitive to the loss or gain of a species and to changes in abundance of low and high frequency taxa. They should also detect proportional changes. None of the community similarity techniques used in this study fulfilled all the above requirements completely. All the similarity techniques assigned similarity values based on the presence of individuals. Perfect replication of cell counts for scarce species added little or nothing to the similarity values. At this time, a combination of statistical techniques using both numbers per taxa and an estimate of total biomass per taxa is recommended for the analysis of phytoplankton community data.
Comparison of Estimates of Hazard Derived at Three Levels of Complexity
Authors: Niederlehner BR , Pratt JR , Buikema AL , Cairns J 
Published: December 2008

Cadmium concentrations constituting a threat to aquatic ecosystems were predicted from data collected at two levels of biological hierarchy. A population-level estimate was derived from single-species toxicity test data, and a community-level estimate was derived from toxicity tests on protozoan communities. Estimates were compared with each other and with an ecosystem-level estimate derived from reports of ecological health and ambient cadmium levels in rivers, lakes, and streams.
Estimates of permissible acute concentrations differed by an order of magnitude. Single-species toxicity test data suggested that 42 μg Cd/L would affect 5% of taxa. The corresponding estimate from the community-level test was 459 μg Cd/L. Similar estimates of permissible chronic concentrations were not significantly different (0.82 and 0.20 μg Cd/L, single-species and community-level tests, respectively). Both estimates of permissible chronic concentrations fell within a rational range, the minimum defined by median cadmium concentrations in healthy aquatic systems (0.05 μg Cd/L) and the maximum defined by median cadmium concentrations in damaged systems (9.2 μg Cd/L).
Community-Level Effects of Coyote Population Reduction
Authors: Schmidt RH 
Published: December 2008

Predator control in the United States is directed primarily at the coyote (Canis latrans). Control programs are constructed to relieve predation losses to livestock. Although a variety of nonlethal control techniques are being used to some degree, lethal control methods continue to be a major part of modern predator control programs.
Toxicants have played a major role in past coyote population reduction programs. Traditional toxicants included strychnine, thallium sulfate, sodium cyanide, and sodium fluoroacetate (compound 1080). The use of toxicants on federal lands was banned by presidential order in 1972; this ban was revoked in 1982. Toxicants may play a larger role in predator control programs if the U.S. Environmental Protection Agency approves registration of any old or new materials for that purpose.
There appears to be an inverse relationship between population levels of coyotes and red foxes (Vulpes vulpes), gray wolves (C. lupus), or other carnivores. When large-scale coyote population reduction programs were successful, red foxes and other medium and large mammalian predators tended to increase. Experimental work and observations on coyote and red fox interactions have shown that coyotes exclude foxes from coyote-occupied habitats. Thus a single-species population reduction program, with toxicants or other means, impacts other members of the medium and large mammalian carnivore guild. The resulting change may impact prey species, because of species-specific prey preferences and foraging tactics, but this is poorly documented.
This paper reviews historical trends of populations of North American canids and recent work on interspecific interactions of canids. In addition, it examines three ecological mechanisms that may be major factors leading to canid competition.
Preliminary Results of Interlaboratory Testing of a Standardized Aquatic Microcosm
Authors: Taub FB , Kindig AC , Conquest LL 
Published: December 2008

Four standardized aquatic microcosm (SAM) experiments were performed at two laboratories to test the reproducibility of controls and copper sulfate treatments. Each laboratory (University of Washington and Duluth-EPA) conducted two 63-day experiments consisting of six replicates each of 0 (control), 500, 1000, and 2000 μg L−1 nominal copper (24 microcosms total). In controls, nitrate was rapidly converted to algal biomass and subsequently to Daphnia. Increasing amounts of copper delayed this conversion. At 500 μg L−1 Cu, algal blooms consistently occurred during the absence of Daphnia. Slightly different amounts of initial copper were related to the duration of these delays. Recovery of the microcosm communities was made possible by detoxification of copper through precipitation, chelation, and sorption, as predicted by the MINEQL copper speciation model. Statistical evaluation of results within each experiment was displayed by an “interval of nonsignificant difference” around the control means. A procedure to statistically compare experiments for reproducibility is being developed, based upon discriminant analysis of distance measures between control and treatment microcosms.
Results from this statistical procedure are presented for the four experiments on three variables (nitrate, Daphnia, algal biovolume). Statistical analyses support the hypothesis that these moderately complex ecological experiments are more similar within laboratories than between laboratories. In spite of this, the conclusions reached from both sets of experiments are similar.
A Microcosm Procedure for Determining Safe Levels of Chemical Exposure in Shallow-Water Communities
Authors: Giddings JM 
Published: December 2008

This paper describes a method for determining safe levels of chemical exposure in shallow-water communities, using laboratory microcosms as test subjects. The safe level is considered to be the maximum exposure that causes no persistent, ecologically significant changes in the ecosystem. Shallow freshwater communities in ponds, lakes, and rivers are good experimental subjects for research on contaminants, and environmental toxicologists have measured their responses to a variety of chemicals. Certain patterns of community effects have been observed, including a decline in net primary production or the production: respiration ratio, concomitant changes in water chemistry, and changes in community composition brought about by interactions among sensitive and resistant populations. The same patterns can be reproduced in microcosms containing natural sediment, water, and communities of submersed aquatic plants (macrophytes). In experiments completed at Oak Ridge National Laboratory, microcosm-derived estimates of safe exposure levels were confirmed using outdoor artificial ponds, suggesting that the microcosm procedure can be an efficient and economical means of determining safe levels for shallow-water communities.
Details of microcosm construction, techniques for monitoring ecological variables in microcosms, and an experimental design for determining safe exposure levels are provided here. The microcosms are assembled by transferring components of natural ecosystems to 80-L aquaria in a controlled laboratory environment. The communities that develop in these systems are typically dominated by common, cosmopolitan littoral species of macrophytes, algae, and invertebrates. Methods are described for measuring changes in water chemistry, phytoplankton, periphyton, macrophytes, zooplankton, and ecosystem production and respiration. By monitoring these variables over a gradient of pollutant exposure levels, the safe level can be determined accurately and precisely.
Zooplankton Community Responses to Synthetic Oil Exposure
Authors: Hook LA , Franco PJ , Giddings JM 
Published: December 2008

While direct toxicant effects on populations can be estimated from single-species bioassay results, the complete range of population and community responses can best be investigated at the ecosystem level. The objectives of this research were (1) to determine the effects of a contaminant (a coal-derived light distillate oil) on the zooplankton communities of laboratory pond microcosms and outdoor experimental ponds, (2) to compare responses of microcosm and field zooplankton communities with each other and with laboratory bioassay data, and (3) to explore the use of community structure data for impact detection.
The responses of the microcosm and pond zooplankton communities to oil treatment were quite similar. Their close agreement lends support for using shallow-water pond microcosms as surrogates for field experiments in hazard evaluation. Changes in cladoceran densities were the most sensitive indicators of stress in the zooplankton communities. Copepods were slightly less sensitive, and rotifers were least sensitive to oil treatment. Indirect effects on populations were observed at intermediate treatment levels. The lowest treatment levels at which persistent and significant ecological changes occurred were the same in both systems. These levels were similar to the lowest observed-effect concentration (LOEC) for the Daphnia magna chronic bioassy, or approximately 3% of the D. magna 48-h LC50.
Community structure responses were generally consistent between systems; however, sensitivity for detecting oil treatment effects varied greatly among the measures of community structure. Species richness and diversity measures were not as sensitive as individual species responses. Cluster and multivariate post-clustering analyses of community similarity values reflected indirect effects and had sufficient sensitivity to allow early impact detection. An expanded principal components technique, which used both zooplankton and water quality data, was also relatively sensitive and would be applicable for routine monitoring.
Production of Coexisting Juvenile Coho Salmon and Steelhead Trout in Heated Model Stream Communities
Authors: Hughes RM , Davis GE 
Published: December 2008

A 4°C temperature differential was maintained between two model streams. Steelhead trout (Salmo gairdneri) were introduced as embryos and retained for one year. The following year, steelhead and coho salmon (Oncorhynchus kisutch) were introduced as embryos and retained together. Macroinvertebrates and fish were sampled every three weeks. Primary production and respiration were estimated seasonally.
Prey biomass and diversity, and the production, biomass, and numbers of steelhead and coho were generally lower in the heated stream than in the control stream. Production, biomass, and numbers of steelhead were lower than those of coho and lower when coho were present than when they were absent. It was concluded (1) that moderate temperature elevation can decrease the productivity of streams for steelhead and coho when food is limited, (2) that coho might reduce the productivity of streams for steelhead more than temperature elevation might, and (3) that model stream results are more likely to corroborate single-species bioassays of fish fed limited rations than of fish fed to repletion.
Leachate Migration Through Clay Below a Domestic Waste Landfill, Sarnia, Ontario, Canada: Chemical Interpretation and Modelling Philosophies
Authors: Quigley RM , Rowe RK 
Published: December 2008

The results of field and laboratory investigations of a domestic waste landfill overlying 30 m of natural clay are presented. Four study phases extending over a ten-year period will be summarized.
Concentration profiles for several soluble constituents (sodium, potassium, calcium, magnesium, Cl− and dissolved organic carbon) show migration to a maximum depth of ∼1.5 m in 15 years. this compares to an advective or seepage advance estimated to be only 3 to 5 cm, indicating migration primarily by diffusion. Concentration profiles for the heavy metals (iron, lead, zinc, and copper) indicate rapid field attenuation with migration to only 10 cm in the carbonate-rich clayey soil.
Graphed solutions to the coupled advection/diffusion equation using constant values for C0+ D, and Vs are only partially successful in predicting the observed chemical profiles because of apparent chemical partitioning at the waste/clay interface. A better fit is obtained by employing an artificial “effective” interface about 25 cm above the observed interface; however, this does not resolve the interface problems.
Recently, new analytical and numerical procedures have been developed for modelling this and other contaminant migration problems. These techniques automatically take into account time-dependent concentration variations within the landfill (for example, because of mass transport into the soil) and allow for a sharp drop in concentration because of surface effects (such as surface smear, drying, and interface partitioning). The numerical solution allows consideration of the effects of a thin but finite interface layer with properties different from those of the underlying soil. Both of these techniques are used in the field case resulting in much superior predictions than earlier models.
Comments are presented on the significance of this work relative to chemical fluxes through thin clay liners.
Low-Cost Data Management for Protection of Ground-Water Resources: The Importance of Quality Assurance
Authors: De Ville WB , Malloy JA 
Published: December 2008

U.S. environmental regulations require the collection, statistical evaluation, and reporting of data associated with ground-water monitoring at hazardous waste facilities. Desktop personal computers are capable of managing the large volume of data and automatically generating the required reports. A functional data base for ground-water monitoring data has been developed for the Apple II personal computer. Design emphasis was placed on error-checking during data entry and on simplicity and consistency of all operations available to the user. This should be considered an integral part of quality assurance/quality control considerations, not only throughout the operations of sampling and chemical and physical measurements, but also throughout all operations involving data entry, storage, manipulation, and reporting.
The programming language used in data base development (a structured BASIC) was chosen to facilitate testing and debugging of program modules. A major design objective was to assure that all operations involved in entry, storage, manipulation, and statistical evaluation of data are well-documented and “bug-free.”
Performance Assessment of Incinerators and High-Temperature Industrial Processes for Disposing of Hazardous Waste in the United States
Authors: Oppelt ET 
Published: December 2008

Since 1982, the U.S. Environmental Protection Agency (EPA) has been conducting performance assessments of hazardous waste thermal destruction facilities in the United States. The principal objective of these tests has been to characterize emissions and determine if these facilities are capable of meeting the waste destruction and control requirements of the current EPA regulations and standards. To date, the test program has involved performance assessments at 9 incinerators and over 20 high-temperature industrial processes employing hazardous waste as a fuel supplement in their operations.
The testing has typically involved stack emissions assessment for SOx, NOx, particulate, hydrochloric acid (HCl), carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2), metals, total hydrocarbon, and quantification of specific organic compound emissions. Engineering and other process operating variables (for example, excess air, steam load, and waste to fuel ratio) have also been recorded during the test program in order to examine the potential operating bounds for these facilities.
The purpose of this paper is to summarize the extensive results of this testing program, which has, in general, indicated that high organic compound destruction and removal efficiencies (99.99%) are achievable in these facilities. Effective (99%) control of HCl emissions was attained in facilities handling chlorinated organic wastes. The current EPA particulate standard of 180-mg/dry m3 was the most difficult standard to attain for incinerators.
Batch Type 24-h Distribution Ratio for Contaminant Adsorption by Soil Materials
Authors: Griffin RA , Sack WA , Roy WR , Ainsworth CC , Krapac IG 
Published: December 2008

An investigation was undertaken to develop a standardized batch adsorption procedure that uses the initial and 24-h solution concentrations to calculate a distribution ratio Rd between solutes and soil materials. In developing these procedures, it was found that the method of mixing the solute-soil mixtures influenced the amounts of solute adsorbed. To ensure reproducibility, a National Bureau of Standards rotating tumbler was adopted as the mixing system. An interval of 24 h was established as a valid operational definition of reaction time for determining Rd values.
Interlaboratory testing was conducted with arsenic and cadmium using soil materials having a range in physiochemical properties. The interlaboratory coefficients of variation (CV) were generally less than 10%. The precision of an Rd measurement for a species that meets the criteria of being stable and nonvolatile should yield percent CV within the range established. The method has not been tested for organic solutes and is not considered viable for volatile chemical species. The method is considered a reliable and useful technique for comparing the adsorption properties of various soil materials under a given set of conditions.
Laboratory and Waste Management for Safety and Regulatory Compliance
Authors: McKee TM , Allison RC 
Published: December 2008

Federal, state, and local rules and regulations often affect even small generators of waste materials. Chemical laboratories are perfect examples with a need to develop procedures to dispose of small quantities of laboratory wastes in a safe and environmentally acceptable manner.
Recognizing a need, the ASTM D-34 committee on waste disposal created its Subcommittee D34.01.05 on Sample Disposal with the direct responsibility for developing guidelines for laboratories. While it was impossible to address the disposal of all wastes from all types of laboratories, the guidelines did address the more common laboratory waste streams. They are applicable, but not limited to, analytical chemistry, process control, and research or life science laboratories.
The recommended guidelines for disposal cover the following topics: (1) the classification of waste for shipping and manifesting by common or generic name and by Department of Transportation requirements; (2) the segregation of wastes for recovery, pretreatment, or disposal; (3) the procedures for recovery of materials, or to render them nonhazardous and amendable for landfilling or in-house disposal, or to prepare them for disposal in authorized chemical disposal sites; and (4) the designation of a specific revoery or pretreatment and disposal method for each type of waste.
Retrofit of a High Power Nd:Glass Laser System with Liquid Crystal Polarizers
Authors: Jacobs SD , Cerqua KA , Kessler TJ , Seka W , Bahr R 
Published: December 2008

The glass development laser (GDL), has been operating at the Laboratory for Laser Energetics since 1978. This Nd:phosphate glass system produces high peak power optical radiation at λ = 1054 nm or λ = 351 nm for use in studying the interaction physics of intense laser beams with matter. The amplifier staging incorporates the propagation of linearly and circularly polarized light in rod amplifiers which vary in diameter from 16 mm to 90 mm. Numerous quartz or mica quarter waveplates and Brewster angle dielectric thin film polarizers are required to limit accumulated phase retardation between amplification stages, and to accommodate interstage Pockels' cell isolation switches.We have recently replaced most of the waveplate-dielectric polarizer combinations in GDL with liquid crystal polarizers. Comprised of 11 μm thick cholesteric fluids sand-wiched between optical quality glass plates, liquid crystal polarizers provide excellent polarization properties, low insertion loss, angular insensitivity, and laser damage resistance at λ = 1054 nm.The design, fabrication and performance of left-handed and right-handed circular polarizers will be discussed.
Pulsed Laser Induced Optical Damage Threshold In Nd:Cr:GSGG Crystal
Authors: Acharekar MA , McCarthy DP , Blachman R 
Published: December 2008

Gadolinium scandium gallium garnet (GSGG) doubled doped with neodymium (Nd) and chromium (Cr) shows higher efficiency than the commonly used neodymium doped yttrium aluminum garnet (Nd:YAG) laser. The performance characteristics of 6.3 mm diameter by 100 mm long and 5 mm diameter by 65 mm long Nd:Cr:GSGG rods were obtained. A flashlamp pumped Nd:Cr:GSGG laser was operated in both normal and Q-switch modes. The performance data for the material will be presented and compared with Nd:YAG laser rod.Q-switch output pulses of Nd:Cr:GSGG laser with 17 ns pulse width and 1.061 μm wavelength were used to study surface and bulk damage in coated and uncoated, polished samples of Nd:Cr:GSGG crystal. These optical damage threshold measurements were compared by measuring damage threshold of fused silica and BK-7 glass samples using the same experimental set up. Nd:Cr:GSGG damage threshold was higher than BK-7 glass and slightly lower than fused silica.