bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the effects of surfactants on freshwater phytoplankton communities in experimental enclosures and on algal population growth in the laboratory
Authors: Lewis Michael A. 
Published: March 2010

Abstract
Field validation of laboratory toxicity data for phytoplankton is uncommon but it is important, since results from standard single-species laboratory tests are often used in assessing the environmental safety of a chemical. This study reports the short-term in situ effects of three surfactants on the community structure of enclosed natural assemblages of phytoplankton. Standard diversity and similarity indices, mean species number and density and changes in dissolved oxygen concentration were determined for phytoplankton enclosed in 26-liter bottles after 10 d of exposure in Acton Lake, Ohio. The first observed effect concentrations based on commonly calculated indices of community structure occurred at 108, 8.4 and 2.9 mg/1, respectively, for the anionic, nonionic and cationic surfactants. In contrast, lower effect levels (&lt;1.0 mg/1) based on changes in density of some major taxa were observed. Since standard algal toxicity tests assume a degree of environmental relevancy, the community effect levels were compared with effect concentrations developed in standard laboratory algal toxicity tests monitoring changes in population growth of single test species. The community effect levels could be predicted in some cases; however, the degree of similarity between the laboratory and field results was very dependent on the surfactant, the laboratory test species and the effect parameter.
Comparative metabolism of o-toluidine by the abalone (Haliotis rufescens) and flatfish (Platichthys stellatus)
Authors: Knezovich John P. , Crosby Donald G. 
Published: March 2010

Abstract
Abalone and flatfish excreted 2-nitrosotoluene and N-acetyl-o-toluidine, respectively, as the only biotransformation products of o-toluidine. The elimination of o-toluidine over a 4-h period was high for both species (greater than 80%), but the total extent of metabolism was low (less than 2%). A Sprague-Dawley rat was used to compare the metabolic pathways typically found in mammals with those found in the marine organisms. Metabolism of o-toluidine by the rat was extensive (greater than 95%), and ring-hydroxylated conjugates were rapidly eliminated.
The metabolic capabilities of terrestrial vertebrates are more extensive than those found in aquatic organisms and may reflect the greater need for water conservation in terrestrial species. Aquatic organisms such as molluscs may not be at a disadvantage, however, because many such compounds are likely to be eliminated by passive diffusion.
Toxicity of pure pentachlorophenol and chlorinated phenoxyphenol impurities to fathead minnows
Authors: Hamilton Steven J. , Cleveland Laverne , Smith Lawrence M. , Lebo Jon A. , Mayer Foster L. 
Published: March 2010

Abstract
The toxicities of pure (greater than 99%) pentachlorophenol (PCP) and of a mixture of the major impurities in commercial PCP, composed mostly of octa- and nonachlorophenoxyphenols (POPs), were evaluated in 90-d partial life-cycle toxicity tests with fathead minnows (Pimephales promelas Rafinesque). The exposure concentrations were 8 to 130 μg/L for the pure PCP and 6 to 93 ng/L for the mixture of POPs. A spontaneous conversion of a 2-hydroxy isomer of nonachlorophenoxyphenol in the POPs mixture to octachlorodibenzodioxin was observed in the stock solution and exposure water during the POPs study. Pure PCP did not affect survival, growth or bone development at any concentration tested. The mixture of POPs did not affect survival but did reduce growth in fish exposed to 93 ng/L for 30 d and stimulated growth in fish exposed to 6 to 47 ng/L for 60 d or to 23 to 47 ng/L for 90 d. Bone development was significantly altered by exposure to POPs concentrations of 12 ng/L or higher; collagen concentration was elevated, and both hydroxyproline concentration (a key cross-linking amino acid in collagen) and bone density were reduced. Degeneration of the fins was noted at 30 d of exposure to 93 ng/L POPs, but fin development appeared nearly normal at 90 d. The sublethal effects of POPs at low concentrations, when compared with those of pure PCP, indicate that POPs may be a major contributor in the toxicity of commercial PCP to fish.
Uptake, translocation and metabolism of anthracene in bush bean (Phaseolus Vulgaris L.)
Authors: Edwards Nelson T. 
Published: March 2010

Abstract
The roots of bush bean (Phaseolus vulgaris L.) plants growing in nutrient solution were exposed to [side ring-U-14C]anthracene (0.01 mg L−1 solution) during flowering and seed production. At harvest, 60% of the total 14C dose was in the roots, 3% in the stems, 3% in the leaves, 0.1% in the pods, 17% in the nutrient solution and 16% unaccounted for. More than 90% of the anthracene (75 mg/plant) was metabolized over the 30-d exposure period. The results suggest that most of the metabolism occurred in the plant tissues. At harvest, 8.7% of the anthracene dose was found (unmetabolized) in the roots, 1.5% in the nutrient solution, 0.53% in the stems and 0.03% in the leaves. Quantities of the parent compound were too small to detect in the pods and seeds. The remainder of the [14C]anthracene taken up by the plants was metabolized to polar metabolites (29%) and nonpolar metabolites (18%) or structurally incorporated into compounds that were not extracted (44%).
DDT contamination of a North Alabama aquatic ecosystem
Authors: Reich Andrew R. , Perkins Jimmy L. , Cutter Gary 
Published: March 2010

Abstract
Between 1947 and 1970, Olin Chemical Company discharged an estimated 4.32 × 105 to 8.0 × 106 kg of DDT residues (DDT, DDD and DDE) into Huntsville Spring Branch and Indian Creek in Alabama. Residents of Triana, Alabama, located approximately 10 mi downstream from the outfall, have been found to have high tissue levels of DDT residues. A comprehensive investigation of the contaminated area conducted by Tennessee Valley Authority and others in 1979 indicated extensive contamination of the ecosystem.
This study investigated the environmental dynamics of DDT residues in the Huntsville Spring Branch-Indian Creek aquatic ecosystem by assessing residue levels in sediment, water and benthic macroinvertebrates collected in September 1983 during a 3-d period. Analytical results revealed continued heavy DDT residue contamination of all three media. Water and sediment data exhibited an exponential decrease in residues with increasing distance below the outfall. Sediments showed concentrations of residues of up to 2% by weight. Benthic macroinvertebrates also displayed high levels of DDT residues. Water bioconcentration factors ranged from 1,737 to 99,700 for total residues.
DDT residue levels in Indian Creek-Huntsville Spring Branch are still extremely high 14 years after the input of DDT was stopped. There has been no significant change in contamination levels during the 4-year interim between this study and the previous TVA study.
Seasonal effects on microbial transformation rates of an herbicide in a freshwater stream: Application of laboratory data to a field site
Authors: Lewis David L. , Freeman Leonard F. , Watwood Mary Elizabeth 
Published: March 2010

Abstract
Seasonal effects on microbial transformation rates of an herbicide, 2,4-dichlorophen-oxyacetic acid butoxyethyl ester (2,4-DBE), in a freshwater stream were investigated using low concentrations (less than 100 μg L−1) of the herbicide mixed with an inert dye, rhodamine WT, to correct for dilution. Although water temperatures decreased from 22 ± 0.5 to 8.0 ± 0.5°C and water velocities decreased from 0.09 ± 0.01 to 0.03 ± 0.003 m s−1, microbial transformation rates, as indicated by pseudo-first-order transformation rate coefficients, increased as much as threefold in the cold months over those in the spring and summer. The increased winter transformation rates were associated with leaf-litter accumulation, which provided additional colonized surface area in the stream. Therefore, the increased colonized surface area more than compensated for the effects of temperature and water velocity (under conditions of mass-transport limitation) that otherwise would have reduced microbial transformation rates in the winter months.
A quantitative method for evaluating avian food avoidance behavior
Authors: Kononen Douglas W. , Hochstein John R. , Ringer Robert K. 
Published: March 2010

Abstract
Food avoidance experiments could contribute to assessments of animals' behavioral responses to environmental toxicants. Food avoidance tests with mallards (Anas platyrhynchos L.) and northern bobwhite (Colinus virginianus L.) as the test species were patterned after avian 5-d dietary LC50 tests. Animals in each treatment group were given free access to untreated feed and feed treated with various concentrations of methiocarb (3,5-dimethyl-4-(methylthio)-phenyl methylcarbamate), a widely used bird repellent. Prior to food avoidance testing, 5-d dietary LC50 tests were conducted to provide baseline data for comparison. A measure of avoidance response was estimated from a log (dose)-probit (response) analysis. The percentage of total (treated plus untreated) feed consumption as treated feed consumption was the response variable. The detectable dietary concentration at which mallards and bobwhite began to avoid a specific contaminant was determined by calculating a median food avoidance concentration 50 (FAC50). In the absence of detectable avoidance behavior, test animals' total feed consumption can be expected to consist of equal amounts of treated and untreated feed. An effective avoidance index (EAI), LC50/FAC50, was used as a measure of a toxicant's “margin of safety.” Calculated results for methiocarb were as follows: for mallard, LC50 = 7,469 ppm, FAC50 = 145 ppm, EAI = 51.5; for bobwhite, LC50 = 827 ppm, FAC50 = 95 ppm, EAI = 8.7.
Aluminate toxicity as a factor controlling plant growth in bauxite residue
Authors: Fuller R. D. , Richardson C. J. 
Published: March 2010

Abstract
Millions of metric tons of alkaline bauxite residue (red mud), produced annually in aluminum refineries at numerous locations around the world, are stored in large, diked impoundments. Bauxite residue is characterized by high pH (9 to 12), high concentrations of soluble sodium, carbonate and aluminate and low concentrations of the major plant nutrients. Establishment of a functioning ecosystem on these derelict lands requires an understanding of the ecological factors limiting plant growth. A series of organic amendments to bauxite residue was tested in order to increase the growth of Distichlis spicata var. stricta (desert saltgrass), an alkaline-tolerant rhizomatous grass. Sewage sludge-amended residue increased shoot growth more than 10 times than did unamended or nutrient-amended residue. Yield was negatively correlated with shoot Al and Fe concentrations' and positively correlated with shoot N, K, P, Ca and Mg content. A hydroponic culture experiment was used to test the effects of high pH (9.5 and 10.5) and aluminate addition (1.0 mM) on the growth of desert saltgrass. Although elevated pH levels reduced Mn uptake, there was very little reduction in growth. The addition of aluminate, however, reduced shoot weight by 67 and 77% at pH 9.5 and 10.5, respectively. Growth reductions were associated with significant declines in shoot P, N, Mg, Ca and K concentrations. At pH 9.5, reductions in shoot P concentrations were associated with large increases in root Al and P levels. At pH 10.5, however, precipitation of an Al-Mg hydroxycarbonate mineral was associated with a decline in shoot Mg levels. Aluminum toxicity appears to be a major factor controlling plant growth in bauxite residue. Possible Fe toxicity needs to be investigated further. Sewage sludge may reduce the toxicity of bauxite residue by lowering pH, precipitating Al and increasing cation availability via complexation.
Xenobiotic metabolism of p-nitrophenol derivatives by the rice field crayfish (procambarus clarkii)
Authors: Foster Gregory D. , Crosby Donald G. 
Published: March 2010

Abstract
The extent and routes of metabolism affect the bioconcentration and toxicity of xenobiotics in crayfish. To investigate the in vivo xenobiotic metabolism of three p-nitrophenol derivatives, rice field crayfish were exposed to 0.1 to 0.01 mg L−1 14C-substrate solutions for 15 h. At apparent steady-state uptake, the crayfish were transferred to a recycling flow-through metabolism chamber for 24 h where the depurated products were collected and concentrated on a column of Amberlite XAD-4 resin. The tissue absorption and distribution of 14C-compounds at the apparent steady-state and post depuration periods were measured by complete tissue combustion and recovery of evolved 14CO2. The structure and concentration of metabolites in resin and soft tissue extracts were determined by cochromatography with authentic standards in HPLC and TLC systems. The crayfish rapidly absorbed the radiolabeled chemicals from solution and depurated metabolites of oxidation and conjugation reactions. The most prominent metabolites were the β-D-glucosides of the free phenols, with lesser amounts of the corresponding sulfate esters. Observed oxidations included O-demethylation, aromatic sidechain oxidation and phosphorothioate deesterification. Body burdens of the original p-nitrophenol derivatives were markedly reduced by the presence of these metabolic transformations.
Determination of uptake rate constants for six organochlorines in midge larvae
Authors: Lohner Timothy W. , Collins William J. 
Published: March 2010

Abstract
Various methods are used to measure the residue-forming potential of organic chemicals in aquatic organisms. The majority of these studies have been conducted with fish and rely on the determination of steady-state partitioning, a method that is expensive, both in terms of time and analytical cost. The midge (Chironomus riparius) is readily available, easily cultured and provides an alternative system with which to study chemical uptake. To evaluate this system, the uptake rate constants of six organochlorines were determined under nonequilibrium conditions, using the midge.
Uptake rate constants were calculated from uptake data using a first-order kinetic expression. Significant correlations were found between the uptake constants of the six chlorinated hydrocarbons and their water solubility and octanol/water partition coefficient values. Multiplying the uptake constants by their molecular weight provided values that were highly correlated with log octanol/water partition coefficients (r2 = 0.93) and log aqueous solubility (r2 = 0.97) when analyzed by linear regression. Using the midge, uptake constants can be determined in a short time and may be used to make reliable predictions about the relative penetrating power of many chemicals in aquatic invertebrates.
Estimating sample requirements for field evaluations of pesticide leaching
Authors: Smith Charles N. , Carsel Robert F. , Parrish Rudolph S. 
Published: March 2010

Abstract
A method is presented for estimating the number of samples needed to evaluate pesticide leaching threats to ground water at a desired level of precision. Sample size projections are based on desired precision (exhibited as relative tolerable error), level of confidence (90 or 95%) and estimates of variability (expressed as the coefficient of variation) for selected pesticide and soil characteristics.
Summary tables of descriptive statistics are provided as guides for projecting variability of various soil characteristics, pesticide properties (sorption, degradation), pesticide concentration profiles and inorganic solutes. These data were compiled through a comprehensive search of review articles and of reports of laboratory and field studies. The parameters selected are measurements generally required for conducting field pesticide leaching studies. They are also useful for evaluating ground water contamination by calibrating and conducting sensitivity testing with solute transport models. Coefficients of variation for selected soil characteristics were as follows: bulk density, 2 to 17%; organic matter, 42 to 125%; porosity, 4 to 18%; particle size distribution, 3 to 55%; hydrogen ion activity, 2 to 15%; 0.3 bar water content, 18 to 82%; 15 bar water content, 18 to 87%; saturated hydraulic conductivity, 48 to 320%; and infiltration rate, 40 to 97%.
Coefficients of variation for selected pesticide characteristics were as follows: transformation rates, 7 to 202%; sorption coefficients, 34 to 56%; and pesticide concentration profiles, 40 to 450%. Variability of pesticide concentrations increased over time after the initial pesticide application. The coefficients of variation for inorganic solutes ranged from 19 to 127%.
On the basis of these data, sample size estimates (for constant desired precision and confidence level) for characterizing selected soil characteristics generally are smaller than those required for estimating pesticide concentrations. Fewer samples are projected for estimating pesticide concentrations shortly after application, with progressive increases required in later sampling.
Products of hexachlorocyclopentadiene (C-56) in aqueous solution
Authors: Chou Sheng-Fu J. , Griffin Robert A. , Chou Mei-In M. , Larson Richard A. 
Published: March 2010

Abstract
The photodegradation and degradation products of hexachlorocyclopentadiene (C-56) in aqueous solutions were studied in the laboratory. In each case, the half-life of C-56 was less than 4 min when exposed to sunlight. At least eight degradation products were positively or tentatively identified: 2,3,4,4,5-Pentachloro-2-cyclopentenone, hexachloro-2-cyclopentenone and hexachloro-3-cyclopentenone were the primary photodegradation products, and pentachloro-cis-2,4-pentadienoic acid, Z- and E-pentachlorobutadiene and tetrachlorobutyne were the secondary degradation products. Dissociation of the primary photolysis products may proceed through corresponding pentadienoic acids to form smaller molecular weight compounds such as pentachlorobutadiene isomers and tetrachlorobutyne. In addition, dimerization of 2,3,4,4,5-pentachloro-2-cyclopentenone to form higher molecular weight compounds such as hexachloroindenone may present a minor route of degradation. The results also indicate that C-56 is highly photoreactive and suggest a possible pathway for the compound's transformation in the environment when exposed to sunlight.
Laboratory studies on mechanisms for the degradation of aldicarb, aldicarb sulfoxide and aldicarb sulfone
Authors: Lightfoot E. N. , Thorne Peter S. , Jones Russell L. , Hansen James L. , Romine R. R. 
Published: March 2010

Abstract
Experiments were performed in order to better define the degradation mechanisms and kinetics for aldicarb and its two metabolites, aldicarb sulfoxide and aldicarb sulfone. The mechanisms studied were oxidation in surface soil and saturated zone soil samples, degradation in saturated zone soil samples and distilled water hydrolysis. The studies showed that soil is an important mechanistic factor, probably because surface catalysis occurs. Temperature and pH are important factors in determining degradation rates. The experiments seem to indicate that microbial oxidation is an important degradation mechanism in the surface soil, but the breakdown of aldicarb residues to noncarbamates is largely the result of chemical hydrolysis. The reduction of aldicarb sulfoxide to aldicarb was observed in the presence of limestone but only after an incubation period of two to six months. No reduction of aldicarb sulfone to aldicarb sulfoxide was observed in these experiments. The complexity of degradation is such that laboratory studies can augment but not replace well-designed experiments conducted under actual field conditions.
Structural features associated with degradable and persistent chemicals
Authors: Niemi Gerald J. , Veith Gilman D. , Regal Ronald R. , Vaishnav Dinesh D. 
Published: March 2010

Abstract
A multivariate statistical method and a heuristic method were employed to examine the structural features associated with the persistence or degradation of 287 chemicals tested with the standard biochemical oxygen demand (BOD) procedure. The data base consisted of 196 “degradable” chemicals with a half-life of less than 15 d (e.g., Theoretical BODs (ThOD) &gt; 16%) and 91 “persistent” chemicals with a half-life of more than 15 d. The multivariate statistical analysis consisted of (1) calculating 54 molecular connectivity indices, five physicochemical properties and eight principal components from the molecular connectivity indices, (2) clustering the chemicals on the basis of the principal components and one of the physicochemical properties, Kow and (3) discriminating between persistent and degradable chemicals using the molecular connectivity indices and the physicochemical properties as discriminating variables within each cluster. The heuristic approach used the results of the multivariate analyses and the literature on biodegradation to identify a series of structural features associated with degradable and persistent chemicals.
The best iteration of the multivariate technique correctly predicted 85% of the degradable chemicals and 94% of the persistent chemicals. In contrast, the heuristic approach correctly predicted 91% of the degradable chemicals and 96% of the persistent chemicals. Twelve structural features or chemical classes were associated with degradable chemicals and 16 structural features were associated with persistent chemicals. The analysis is presented as a potential technique for rapidly assessing the relative degradability of discrete organic chemicals. The structural features identified are offered as tentative hypotheses to be examined with a larger and more diverse data set.
Uptake and release of fluoride in arctic char
Authors: Christensen B. 
Published: March 2010

Abstract
Fluoride levels were measured in Arctic char (Salvelinus alpinus) living near Narsaq. The Narsaq River is unpolluted, but has naturally high levels of fluoride—varying from about 2 mg/L in summer to 10 to 20 mg/L in winter. The river has a relatively large population of Arctic char which appears unaffected by the high fluoride level. Stationary char accumulate fluoride in muscles (16.6 mg/kg) and bones (1,150 mg/kg), while char caught in the estuary have concentrations similar to char from reference areas (6.5 mg/kg in muscle, 439 mg/kg in bone). It is concluded that Arctic char accumulate fluoride when living in the high-fluoride freshwater environment, but that concentrations return to normal in anadromous char during the 1 to 2 summer months annually spent at sea.