bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resolving Some Practical Questions About Daphnia Acute Toxicity Tests
Authors: Barera Y , Adams WJ 
Published: March 2009

Acute toxicity tests were performed with six age groups of Daphnia magna, ranging from ≤6 h to 216 h, and with five chemicals, selected on the basis of their physical and chemical properties as well as their acute toxicity to D. magna. The age of the daphnids did not significantly alter the 48-h EC50 values for the chemicals tested. The maximum difference observed in the 48-h EC50 values between the 6-h and 216-h age groups was a factor of 3.9 for linear alkylbenzene sulfonate (LAS). For purposes of standardization, it appears that D. magna up to 48 h of age at the beginning of the test can be used to conduct acute toxicity tests with most chemicals.
The results of static acute toxicity tests conducted with butylbenzyl phthalate (BBP) and D. magna in the presence and absence of several commonly used solvents indicate that the acute toxicity of this chemical is not altered by the use of a solvent carrier. The 48-h EC50 value for BBP without a solvent was 1.0 mg/L, compared with a range of 1.6 to 2.2 mg/L when acetone, dimethylformamide, ethanol, or triethylene glycol were used as solvent carriers. The acute toxicities of the solvents in the absence of BBP were also determined for D. magna. The values ranged from 9.3 to 52.4 g/L.
The results of static acute tests performed with D. magna and BBP in the presence of various concentrations of daphnid foods (algae or trout chow), indicate that the 48-h EC50 values increase proportionally with an increase in food concentrations. These results suggest that acute toxicity tests with D. magna should be conducted in the presence of food with chemicals with a high Koc if the results are to be used to select the test concentrations for a chronic study with daphnids. The type of food and the concentration used in the acute test should be the same as those used in a chronic test.
Effect of Storage on Leaching Properties of Metal-Finishing Sludges
Authors: Saunders FM , Williams FM , Kutz RG 
Published: March 2009

Leaching properties of thickened sludge suspensions and dewatered sludge cakes from an aluminum-anodizing and an electroplating plant were examined. Sludge specimens were examined before and after 27 to 207 days of storage under controlled conditions using the Environmental Protection Agency (EPA) extraction procedure (EP). Extracts were examined for silver, aluminum, cadmium, chromium, copper, mercury, nickel, lead, and zinc. Extract metal concentrations varied considerably with time of storage with no consistent pattern for all metals in either sludge.
The electroplating sludge was classified as hazardous using EPA standards for EP results. Cadmium levels in the sludge were initially 5 mg/L and increased to 13 mg/L following storage for 98 days for both the stored suspension and the stored dewatered cake specimens. Extract chromium and copper concentration decreased with storage time while those for lead decreased initially and then increased with storage time. Although extract metal concentrations for the aluminum-anodizing sludge varied with storage time, metal concentrations were well below levels designated as hazardous by EPA.
Filtrate metals were shown to have minimal impact on EP test results and the majority of extracted metals were from suspended metal precipitates in the sludges. Sludge storage was shown to have a significant effect on EP test results, indicating a need to recognize it as a test variable.
Batch and Column Extraction Procedures for Organics in Solid Wastes
Authors: Maskarinec MP , Brown DK 
Published: March 2009

Because of the possibility of contamination of aquifers by solid waste leachates, it is important to develop laboratory extraction procedures that predict the release of organic materials from landfills. This paper presents the results of a study comparing five laboratory extraction procedures with respect to the organic content of the extract. Nine solid wastes, representing a wide variety of matrices, were considered. The extraction procedures used were the Environmental Protection Agency Extraction Procedure (EPA-EP), a distilled water extractant, a citrate buffer extractant, a sodium ion-exchange resin extractant, and an upward-flow column extraction test.
Organic analysis of the batch extracts was carried out by isolation/concentration of the leachates with XAD-2 resin, followed by gas chromatography on fused silica capillary columns. In the case of the upward-flow column extraction, a cartridge containing XAD-2 was placed directly at the column exit; the resin was isolated/concentrated in a manner identical to the batch extracts.
The results were assessed both in terms of total chromatographable organics (TCO) and in terms of the levels of individual compounds. The column technique gave consistently higher results in terms of TCO. This effect is in large measure due to enhanced recovery of highly volatile compounds and nonpolar compounds. The results of the extraction of individual compounds were less consistent. The recovery of carboxylic acids, for example, depended primarily on pH. The recovery of volatile organics, on the other hand, was more closely related to the extraction vessel used than to the extractant.
Thus, it may be concluded that the column procedure most aggressively extracted organics from the solid wastes. However, the chemical nature of the organic material in the solid waste determines which of the batch extraction procedures is most aggressive.
Development of a Method for Determining Purgeable Organic Compounds in Solid Wastes
Authors: Warner JS , Slivon LE , Meehan PW 
Published: March 2009

This study was undertaken to develop an improved method for determining the total content of individual volatile organic compounds in industrial solid wastes. The objective was the development of a method that would (1) be applicable to a wide range of specimen matrixes, (2) be applicable to a wide range of purgeable compounds, (3) have a detection range of 1 ppm to 100%, (4) give acceptable recovery and reproducibility, and (5) be easily performed at a reasonable cost.
The waste matrixes of interest included aqueous sludges, dry solids, soils, tars, oil, and oily sludges. The compounds of interest included purgeable halocarbons, hydrocarbons, ketones, ethers, esters, sulfides, and nitriles having boiling points in the range of −30 to 180°C.
The method developed involves a combination of solvent extraction and a purge and trap technique. The main features of the method are simply (1) solvent extraction with tetraglyme, a nonvolatile, water-miscible and oil-miscible solvent, (2) dilution of the extract with solvent as necessary, and (3) purge-and-trap analysis of an aliquot of the extract. Recommended techniques for the final analysis step include gas chromatography with detection by mass spectrometry, flame ionization, electron-capture, Hall electrolytic conductivity, or nitrogen and phosphorus specific thermionic detection to determine individual compounds, and microcoulometric analysis to determine the total purgeable organic halogen content.
In addition to meeting the specified requirements, the method has the advantage of being readily integrated with sampling and specimen handling to avoid losses of volatile compounds before analysis.
Evaluation of On-Site Soil for Use as an Impoundment Liner
Authors: Hansen LA , Weeks RE , Shrestha RK 
Published: March 2009

The results of geotechnical and geochemical tests on four on-site soils considered for construction of a liner for a proposed uranium tailings impoundment are presented. The interaction of five heavy metals (arsenic, chromium, zinc, molybdenum, and manganese) with four clay soils was investigated by batch tests on pulverized specimens and column tests on compacted specimens. A prototype mill tailing solution was used for the column leaching tests.
Atterberg limits, metal concentrations, and X-ray diffraction analyses established two soil groups of similar composition. The batch and column tests established two soil groups having similar adsorption characteristics, but they included soils having different compositions. The results of batch and column tests were in general agreement, though a few significant differences in adsorption characteristics were noted. The testing established a tentative ranking of the relative sorptive capacities of the four soils for the five metals, though further testing is recommended.
The Great Bioassay Hoax, and Alternatives
Authors: White HH , Champ MA 
Published: March 2009

A review of recent literature reveals large variations in results of bioassays, such as those proposed for solid waste testing. Sources of variation are categorized, and an estimate is made of the range in test results attributable to each source category. The age of the test organism is potentially the largest source of variation, and has effects up to five orders of magnitude on the outcome of bioassays. Other sources of variation have effects of several orders of magnitude, and nearly all sources have at least one-order-of-magnitude effect. It is concluded that bioassays cannot be used to predict the impact of contaminants introduced to an ecosystem or population, and therefore serve poorly as a tool in pollution management.
Three criteria are proposed for judging the utility of any pollution evaluation technique. These are: the ability to incorporate good scientific practice in any application; the relationship of the measured response to the natural field response; and the relationship of the measured response to important ecosystem processes. Multi-species tests in micro- and mesocosms usually satisfy these criteria better than single-species tests, and may also be used to help develop simpler tests that satisfy these criteria. The focus of impact evaluation must be on growth, reproduction, and survival, and parameters that can be related readily to them. Lastly, pollution management schemes have always recognized that human interests are the sole standard of which ecosystem effects are “harmful,” and which are not.
Methods Using Earthworms for the Evaluation of Potentially Toxic Materials in Soils
Authors: Neuhauser EF , Malecki MR , Loehr RC 
Published: March 2009

The purpose of this study was to investigate the feasibility of using earthworms to indicate effects of potentially toxic wastes when such wastes are intentionally or accidentally added to soils. Initial work with metals has shown that earthworms exhibit specific growth and reproductive responses. These responses are related to the concentration and solubility of the metal. Of the metals tested, cadmium was found to be the most toxic, followed by nickel, copper, zinc, and lead.
The metal concentration in earthworm tissue and the background manure-metal mixture was measured, permitting the concentration factor to be computed. The concentration factor is the ratio of the metal in the worm tissue to that in the surrounding manure-metal mixture.
These and other studies in our laboratory have demonstrated that the methods described in this paper may be used to predict the effect of land-applied or atmospherically deposited residues on the soil biota.
Prediction of Chemical Mobility in Soil from Sorption Coefficients
Authors: McCall PJ , Swann RL , Laskowski DA , Vrona SA , Unger SM , Dishburger HJ 
Published: March 2009

Several methods of evaluation have been proposed to classify the mobility of chemicals through soil. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) guidelines recommend use of soil columns to assess mobility, whereas the Toxic Substances Control Act (TSCA) guidelines propose the use of soil thin-layer chromatography (TLC). The soil sorption coefficient of a chemical has been recognized as the major factor controlling its mobility; however, confidence in this measurement as a sole means to estimate mobility has not been demonstrated.
Therefore, column leaching experiments have been conducted which correlate the soil adsorption coefficient with movement. Soil columns, eluted under controlled conditions with 50 hectare cm (20 acre in.) of water, have been studied with nine chemicals and three soil types. A simple relationship has been developed which demonstrates that, when the soil adsorption coefficient is known along with the organic carbon content of the soil, predictions regarding movement by means of leaching can be made.
Since a standard adsorption coefficient based on organic carbon content, Koc, can be determined independent of other soil properties, prediction of movement of a chemical through any soil is possible if the organic carbon content of the soil is known.
Analysis of Variance as a Method for Examining Contaminant Residues in Fish: National Pesticide Monitoring Program
Authors: Schmitt CJ 
Published: March 2009

Contaminant monitoring programs are designed to determine temporal and geographic trends in residue concentrations. Obvious interpretive problems may arise from analytical changes, inconsistent replication, and other activities that upset a program's continuity. Less obvious difficulties, related to the inherent nonnormality of residue data and the abilities of the data to meet many of the assumptions required by statistical methods, present themselves during the analysis, testing, and interpretation of results.
Statistical analysis of monitoring data is traditionally accomplished by testing the differences between location or time-period means with a two-way factorial analysis of variance (AOV) in which variation accrues from locations, time periods, time × location interaction, and error. Without replication, interaction is usually assumed to be absent when main effects are tested, which is a questionable practice with residue data. Adding the species, species type, or sample type effects to the two-way factorial results in a three-way factorial involving more complex interactions. An alternative to the full factorial AOV—analysis as a partially nested factorial—is presented for use when the species collected are not common to all locations and time periods. All analyses are illustrated by using a selected subset of National Pesticide Monitoring Program data for organochlorine residues in freshwater fish.
Depending on the monitoring program's objectives and how the stations were selected, location effects may be considered random rather than fixed. This may result in a mixed-model AOV and alter the computation of F-ratios for time-period main effects, possibly changing the outcome of significance tests and resulting conclusions regarding temporal trends.
Statistical Analysis of Fish Chronic Toxicity Test Data
Authors: McClave JT , Sullivan JH , Pearson JG 
Published: March 2009

This paper presents methodology for the analysis of chronic toxicity test data. Emphasis is given to the determination of the lowest tested concentration whose mean response differs significantly from the control. In particular, the analysis of variance (ANOVA) approach for analyzing chronic toxicity test data is discussed in some detail.
The paper presents four experimental designs that have different experimental units, that is, the units on which the observations or measurements are made. The first type of experimental design is a completely randomized design in which the aquaria are the experimental units. The second is a nested design, with aquaria nested in concentration and fish nested in aquaria. The third is also a nested design, in which aquaria are nested in concentrations, fry chambers are nested in aquaria, and fish are nested in chambers. The fourth is a two-factor design in which sex is crossed with concentration. The final section of the paper is a general discussion of the utility of the ANOVA approach, its limitations, and the identification of some areas that still need research.
Development and Evaluation of a Flow-Through Growth Inhibition Test with Duckweed (Lemna minor)
Authors: Bishop WE , Perry RL 
Published: March 2009

Duckweed, Lemna minor, has been proposed as a “typical” aquatic macrophyte suitable for laboratory toxicity testing and useful in the environmental hazard assessment of chemicals. The development of a standard, reproducible, flow-through growth inhibition test with duckweed that employs a precisely controlled flow rate, automatic nutrient and test material delivery system, and constant light intensity is described. The test materials included a heavy metal; anionic, nonionic, and cationic surfactants; and an aquatic herbicide. Growth inhibition was measured as a reduction in frond count, dry weight, and root length. Results based on frond count were found to provide the most useful information per unit of laboratory time. The 7-day median effective concentration (EC50) based on frond count ranged from 0.0031 mg/litre for the herbicide to 43 mg/litre for an anionic surfactant. The ecological relevance of EC50 measurements for duckweed growth is unknown.
Results obtained with duckweed were compared with acute toxicity data for fish and aquatic invertebrates. For all materials except the herbicide, duckweed was the least sensitive species. The data developed indicate that for many materials, criteria developed for fish and invertebrates may be extended to include the macrophyte community.
Thermal Degradation of Cable and Wire Insulations
Authors: Alvares NJ , Lipska-Quinn AE , Hasegawa HK 
Published: March 2009

The major proportion of available flammable materials in energy research facilities consists of the coverings and insulations for electrical conductors in control, power, and diagnostic circuits. Since quantitative information on flammability of insulations is sparse, we initiated a program to investigate these properties. Our objective is to develop data applicable to predictions of fire risk parameters for large experimental energy facilities and, ultimately, new power generating plants. Our procedures involve measuring evolution of corrosive products as well as other thermal degradation products in air and nitrogen. We use a thermogravimetric analyzer to study effects of heating rate on modes of degradation and a heat release rate calorimeter to survey effects of thermal irradiance levels on product generation and the heat release rate of insulation materials.
Thermal measurements—heat release rate, flame spread rate, and ease of ignition—show that common insulating materials are not easily ignited and that they burn with relatively little heat output and slow flame spread. However, when conditions are right, thermal rate parameters can interact to produce intense, fast-moving fires. Such conditions occur where the surface-to-volume ratios of conductors are great, enhancing both fuel availability and heat feedback from flames. In large energy research and production facilities, this condition is common.
Silicon Crystal Growth and Processing Technology: A Review
Authors: Bonora AC 
Published: March 2009

Crystal growing and shaping technologies are being influenced by a combination of new discoveries in materials properties and new requirements from the marketplace. Key elements of change in crystal growth include control of carbon and oxygen, coupled with a transition to computerized large-charge growers, and investigation of magnetic field influence.
Materials shaping is being driven by stringent quality requirements coupled with newly available processing technologies including laser marking, gettering, and edge profiling. New instruments for inspection of particles, material composition, and wafer flatness are contributing to an overall trend towards automation of critical processes. Planarity of the polished slice continues to be a significant concern, since some complex lithography processes show performance gains with ultraflat wafers.
Effects of Processing Parameters on Shallow Surface Depressions During Silicon Epitaxial Deposition
Authors: Boydston MR , Gruber GA , Gupta DC 
Published: March 2009

Buried layer patterns of high dopant concentration are required in semiconductor processing. These patterns are produced by diffusion through patterned oxide and are marked by shallow flat-bottomed depressions bounded by steps of a few hundreds to a few thousands angstroms in height.
The shape and position of the surface depressions relative to the original buried layer patterns are affected by various parameters and processing steps during epitaxial deposition.
Data from a barrel reactor are presented on the lateral displacements of surface depressions, showing the dependence of deposition parameters on symmetrical and asymmetrical distortions. Horizontal and barrel reactor configurations are compared.
Polyimide-Substrate Effects During Wet Chemical Processing of Polyimide Films in VLSI
Authors: Belton DJ , van Pelt P , Morgan AE 
Published: March 2009

The application of polyimides as insulators in multilevel interconnect systems is receiving considerable attention for very-large-scale integration (VLSI) production. For a tight control of wet chemical pattern formation, as well as for the ultimate adhesion in the finished device, a fundamental understanding of polymidesubstrate interactions is important.
We have examined the effects of molecular weight, chemical composition, and interphase structure on the dissolution behavior of polyimides on silicon substrates. The dissolution rate of partly cured polyimides was found to depend strongly on the above parameters, and showed distinct regions of behavior. The overall-etching characteristics of the materials examined were dominated by surface adhesive interactions.
A method was developed to quantify the chemical adhesion during etching of polyimides. A phenomenological model of the dissolution behavior will be presented and its implications for VLSI processing will be discussed.
Modeling Anomalous Junction Formation in Silicon by the Codiffusion of Implanted Arsenic with Phosphorus
Authors: Fair RB , Meyer WG 
Published: March 2009

Cross-contamination of phosphorus in arsenic-implanted layers has been found to occur in mechanically scanned ion implantation systems. Phosphorus introduced at low levels exhibits a diffusivity that depends upon n2, where n is the free electron concentration of the highly doped arsenic background layer. If the arsenic layer is shallow and the phosphorus diffuses through the arsenic junction, an enhanced phosphorus tail region is formed. Tail diffusion coefficients at 900°C were ∼20 times greater than the intrinsic phosphorus diffusion coefficient. Also, when a phosphorus tail is formed, the mechanism that enhances the tail diffusion also enhances the high concentration arsenic diffusion. These results are remarkable, since arsenic by itself will not produce an enhanced tail during diffusion in silicon, nor will it cause any emitter push effect.
These results have been modeled and provide strong support for a Fermi-level-controlled point-defect model of phosphorus diffusion with impurity-point-defect pair dissociation creating the tail region. We have essentially duplicated high-concentration phosphorus diffusion results by replacing the highly doped portion of the profile with arsenic. The fact that arsenic diffusion is also predictably enhanced when a phosphorus tail is formed strongly implies that the point-defects involved are vacancies.