bluuebunny/crossref_metadata_2025_split huggingface dataset:
A pharmacokinetic analysis of the uptake of polychlorinated biphenyls (PCBs) by golden shiners
Authors: Karara Adel H. , Mcfarland Victor A. 
Published: March 2010

Abstract
A 96-h, static, nonconstant exposure design was used to assess pharmacokinetic parameters and to identify the rate-limiting process in polychlorinated biphenyl (PCB) uptake by golden shiners (Notemigonus crysoleucas). Fish were exposed individually to 14C-labeled PCBs corresponding to Aroclor 1254 (A1254). After various intervals (2–96 h), fish and water were analyzed for total radioactivity. Uptake of PCBs and decline of the external water concentration were both rapid. A clearance constant-based one-compartment model was used to represent the fish. Model-based equations for PCB concentrations in the fish and in the water were fitted simultaneously to the observed data with the PCNONLIN™ computer program. The absorption clearance constant was 30.8 ml·h−1·g−1 fish, which identified gill blood flow as the uptake rate-controlling process. The model-predicted apparent volume of distribution, Vd, and bioconcentration factor, Kb, were 5,280 ml/g fish and 9,059 ml water per gram fish, respectively. The model-predicted elimination rate constant, ke, was 5.84 × 10−3h−1, corresponding to a t1/2 of 4.9 d.
Evaluation of EPA's rapid bioassessment benthic metrics: Metric redundancy and variability among reference stream sites
Authors: Barbour Michael T. , Graves Carol G. , Plafkin James L. , Wisseman Robert W. , Bradley Brian P. 
Published: March 2010

Abstract
The data analysis scheme used in the U.S. Environmental Protection Agency's (EPA's) rapid bioassessment protocols (RBPs) integrates several community, population, and functional parameters (or metrics) into a single assessment of biological condition. A reference data base of macroinvertebrate data obtained from 10 ecoregions in Oregon, Colorado, and Kentucky was used to evaluate the appropriateness and variability of the benthic metrics and the similarities of results among ecoregions. Several statistical procedures, including principal component analysis, correlation coefficient, analysis of variance, and stepwise discriminant analysis, were used to test the efficacy of 17 community metrics. A general separation between the mountain ecoregions and the valley/plains ecoregions was determined to exist for the metrics. Two of the original eight metrics described in the EPA's RBPs for benthic macroinvertebrates were found to be highly variable and unreliable as measures of biological conditions in some ecoregions. Eleven metrics were determined as being valuable in discriminating between montane and valley/plains groupings of ecoregions.
Predictive model for aerobic biodegradability developed from a file of evaluated biodegradation data
Authors: Howard Philip H. , Stiteler William M. , Meylan William M. , Hueber Amy E. , Beauman Julie A. , Larosche Michael E. , Boethling Robert S. 
Published: March 2010

AbstractA file of evaluated biodegradation data was used to develop a model for predicting aerobic biodegradability from chemical substructures. Chemicals initially were divided into three groups: (a) chemicals that degrade rapidly under most environmental conditions without requiring acclimation; (b) chemicals that are biodegradable, but only after an acclimation period; and (c) chemicals that degrade slowly or not at all. Chemicals in the first and last groups were then used to develop a model for classifying chemicals as rapidly biodegradable or not rapidly biodegradable. Two models, one based on linear regression and the other based on nonlinear regression, were developed from 35 preselected substructures. Both models predict the biodegradation categories correctly 90% of the time for the training set (264 chemicals) and an independent validation set (27 chemicals), and are 95% correct for chemicals that biodegrade rapidly.
Emerging insects as a biotic pathway for movement of 2,3,7,8-tetrachlorodibenzofuran from lake sediments
Authors: Fairchild Wayne L. , Muir Derek C. G. , Currie Robert S. , Yarechewski Alvin L. 
Published: March 2010

Abstract
Emerging insects are a potential biotic transport route for export of contaminants sequestered in lake sediments to surrounding aquatic and terrestrial ecosystems Emerging insects (mainly Diptera) were collected from four lake mesocosms treated with 10 μg of sediment-sorbed 2,3,7,8-tetrachlorodibenzofuran Insects emerging from the mesocosms had a mean contaminant concentration of 228 pg/g wet weight Contaminant export by emerging insects was from 0 2 to 2 1% of the total sediment contaminant content annually
QSARs based on fuzzy adaptive least-squares analysis for the aquatic toxicity of organic chemicals
Authors: Liu Qian , Hirono Shuichi , Matsushita Yasuo , Moriguchi Ikuo 
Published: March 2010

Abstract
A quantitative structure-activity relationship (QSAR) model for the prediction of aquatic toxicity of organic chemicals was formulated. Toxicity data of 394 compounds with a wide variety of structures were collected from a data base and other literature. The molecular structures were quantitatively described, using substructural and hydrophobic parameters for the QSAR analysis. Fuzzy adaptive least-squares (FALS), a pattern recognition method recently developed at our laboratory, was used in the QSAR study. A discriminant function with 37 variables was obtained, representing satisfactorily the correlation of structure with aquatic toxicity ratings of compounds. The results were highly significant both in recognition and in leave-one-out prediction.
Quantitative modeling of environmental fate and impact of commercial chemicals
Authors: Sabljić Aleksandar , Piver Warren T. 
Published: March 2010

AbstractPresent laws in many countries require that all commercial chemicals be assessed for their environmental behavior and hazards. Because there are a large number of chemicals currently in common use (approximately 100,000) and new chemicals are being registered at a very high rate (1,000 per year), it is obvious that our human and material resources are insufficient to obtain experimentally even basic information about environmental fate and effects for all these chemicals. Thus, it is necessary to develop quantitative models that will accurately and rapidly predict environmental behavior for large sets of chemicals. During the last decade, a considerable effort has been made to develop methods that use molecular characteristics to describe environmental behavior of organic pollutants. Thus far, molecular connectivity indexes have been shown to be the most successful structural property for describing and predicting soil sorption coefficients, association coefficients with dissolved humic substances, Henry's law constants, bioconcentration factors in aquatic organisms and vegetation, biodegradation rates, and fish acute toxicity. The general quantitative model, based on the first-order molecular connectivity index (MCI), has been developed for the accurate estimation of soil sorption coefficients for predominantly hydrophobic chemicals: polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), halogenated hydrocarbons, and phenols. It is possible to extend this model for many classes of agricultural chemicals. A similar model, based on the second-order valence MCI, has been developed for fish bioconcentration factors of PCBs, chlorinated diphenyl oxides, halogenated hydrocarbons, PAHs, and phenols, plus substituted benzenes. Furthermore, a prototype expert system has been developed for classifying untested chemicals as readily or not readily biodegradable, based on their chemical structures. Finally, using a standardized data base for fish acute toxicity, we have obtained a simple linear correlation between the valence zero-order MCI and the 96-h LC50 data for a large group of 150 structurally diverse commercial chemicals.
An evaluation of nickel toxicity to Ceriodaphnia dubia and Daphnia magna in a contaminated stream and in laboratory tests
Authors: Kszos Lynn Adams , Stewart Arthur J. , Taylor Paul A. 
Published: March 2010

Abstract
Seven-day tests with Ceriodaphnia dubia were used to document ambient toxicity in two industrially contaminated streams in southeastern Tennessee. Low survival of Ceriodaphnia dubia was linked to concentrations of Ni (74-200 μg/L) below Environmental Protection Agency (EPA) water quality criteria. A toxicity identification evaluation consisting of Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas (fathead minnow) toxicity tests with Ni, chemical analyses, and experiments with a Ni-selective resin were used to show that Ni was the primary toxicant in one of the streams. Nickel nitrate and Ni chloride were both extremely toxic to Ceriodaphnia dubia but were not very toxic to Pimephales promelas: Ni at a concentration of 7.5 μg/L (water hardness, 40 mg/L as CaCO3) was lethal to Ceriodaphnia dubia within 7 d, but 16 mg/L Ni did not reduce survival or growth of Pimephales promelas. When dilution water with a hardness of 177 mg/L was used, 15.0 μg/L killed all the Ceriodaphnia dubia in 7 d (no reduction in survival or fecundity occurred in 7.5 μg/L). Daphnia magna was less sensitive than Ceriodaphnia dubia to Ni: A concentration of 40 μg/L significantly reduced fecundity but not survival in 21 d. In stream water containing 49 μg/L Ni (hardness, 656 mg/L), 100% mortality of Ceriodaphnia dubia occurred in 7 d, but 70% of the Daphnia magna survived for 14 d. When the Ni in the stream water was reduced to 10 μg/L with the resin, 60% of the Ceriodaphnia dubia lived for 7 d and all the animals reproduced; survival and reproduction of Daphnia magna remained high for all 14 d. Thus, in both ambient water and pure chemical tests, Ceriodaphnia dubia was found to be much more sensitive to Ni than Daphnia magna. Experiments with 63Ni showed that both species accumulated similar amounts of Ni, so the difference in toxicity was not a result of Ni uptake. The high sensitivity of Ceriodaphnia dubia to Ni and the lower than expected reduction in Ni toxicity to Ceriodaphnia dubia with increasing hardness have important implications for effluent and ambient testing and toxicity reduction efforts.
An overview of global warming
Authors: Mohnen Volker A. , Wang Wei-Chyung 
Published: March 2010

Abstract
Temperature records indicate that the global annual mean surface air temperature (referred to as the global temperature) has risen by 0.5°C since 1840. According to recent general circulation model calculations, by the year 2020 the global mean temperature will have risen to 1.3 to 2.5°C above the preindustrial (1840) mean. By the year 2070, the range of temperature increase will be 2.4 to 5.1°C, and sea level will have risen 33 to 75 cm. Measurements from Antarctic ice cores show temperature swings of 4 to 5°C between ice ages and interglacial periods. Fossil fuel-based energy use through power generation and transportation is viewed as the major cause of the very recent and projected future temperature rise. Recent arguments of scientists and policy makers have increasingly focused on the exact scope of global-scale changes and consequences of the globally rising energy appetite. The question of global warming has become the most important scientific issue.
Impact of ozone on loblolly pine seedling foliage production and retention
Authors: Kress Lance W. , Lee Allen H. , Mudano Jane E. , Stow Tara K. 
Published: March 2010

AbstractField-grown one-year-old loblolly pine seedlings were exposed to a complete factorial design of ozone and acidic precipitation in open-top chambers for two seasons. Foliage production and retention were evaluated during the second exposure season. Five ozone exposures ranging from 0.42 to 2.95x ambient and two rainfall treatments, pH 5.3 and pH 3.3, were applied for two growing seasons. Fascicle number and length of early season flushes were decreased by increasing ozone, but ozone increased fascicle length of late season flushes. Foliage retention was significantly decreased as ozone concentration increased. A significant reduction in fascicle retention was observed at ambient ozone concentrations. Significant pine family differences were noted for many of the evaluated foliage variables. Acidic precipitation generally had no significant effects, except that overall branch foliage retention tended to increase with increasing acidity and there was an ozone by rain acidity interaction when 1987 branch foliage was evaluated. Decreased foliage retention may be a partial explanation for the growth rate reductions in some stands in the Southeast.
Evaluating the statistical bases for relating receiving water impacts to effluent and ambient toxicities
Authors: Marcus Michael D. , McDonald Lyman L. 
Published: March 2010

Abstract
The U.S. Environmental Protection Agency's Complex Effluent Toxicity Testing Program (CETTP) investigated the relationship of ecological conditions in eight receiving water systems to toxicities in both discharged effluents and ambient receiving waters. Our evaluation of the CETTP studies showed that they included no statistical evaluation of relationships between effluent toxicity and instream effects. We found that (a) limitations in the designs for these studies prevented statistically based inferences using relationships reported between ambient toxicity and instream impacts to other sites or to other times at these sites; (b) relatively few significant correlations existed between pairs of ambient toxicity and instream community variables; (c) the CETTP method for correlating maximum ambient toxicity to maximum instream impact generally reduced correlation between pairs of variables; and (d) the CETTP method used to show percentages of “correct predictions” by laboratory toxicity projections of instream impacts was mathematically biased and inappropriate. We show that canonical correlation analysis is a potentially useful approach for evaluating relationships between matrices of laboratory toxicity and field community measures. Our results indicate that the short-term chronic test results for ambient waters can potentially provide useful information relating to biological community structure in streams where toxicity is a predominating habitat influence.
Enhancement to the pielou method for estimating the diversity of aquatic communities
Authors: Clark Malcolm John Roy 
Published: March 2010

Abstract
The Pielou abundance ratio method of estimating the diversity of aquatic communities by plotting the relative abundances of the three most common species per sample on ternary plots has been further developed. Algorithms are presented that permit the ternary plots to be readily produced via any computer spreadsheet having orthogonal graphics capability. The Pielou method is modified to present time-series-diversity data as chronological tables or plots similar to those used for other water-quality variables and to accommodate n-dimensional relationships. The modified method is applied to phytoplankton data from two lakes, one impacted by acid mine drainage and one pristine.
Temperature dependence of henry's law constants for selected chlorobenzenes, polychlorinated biphenyls and polycyclic aromatic hydrocarbons
Authors: Hulscher Th.E. M. Ten , Van Der Velde L. E. , Bruggeman W. A. 
Published: March 2010

Abstract
Modeling the fate of organic micropollutants in aquatic systems requires information about gas/water partitioning at environmental temperatures. In this paper experimental data are presented on Henry's law constant (H) for seven chlorobenzenes, three polychlorinated biphenyl (PCB) congeners, and six polycyclic aromatic hydrocarbons (PAHs). The studied compounds were 1,2,3–; 1,2,4– and 1,3,5–tri–; 1,2,3,4– and 1,2,3,5–tetra–; penta–; and hexachlorobenzene; 2–5–di–; 2,4,4′–tri-; and 2,2′5,5′–tetrachlorobiphenyl; and the PAH compounds fluoranthene, benzo[b]flu-oranthene, benzo[kfluoranthene, benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3–cd]pyrene. H was measured in a buffer solution using a modified gas-purge technique. Values for this set of PAH compounds have not been determined experimentally before. The temperature dependence of H was measured for the tetra-, penta-, and hexachlorobenzenes and for all PCBs and PAHs over a temperature range of 10 to 55°C. The experimental data and temperature dependence are in good agreement with partitioning theory and available literature data. The observed temperature dependence results in a doubling of H for every 10°C temperature increase.
Modeling pesticide movement in forested watersheds: Use of przm for evaluating pesticide options in loblolly pine stand management
Authors: Dowd J.F. , Bush P.B. , Berisford Y.C. , Neary D.G. , Taylor J.W. 
Published: March 2010

Abstract
The fate of pesticides in forest ecosystems is strongly influenced by climatic conditions. Drought or excessive rainfall may seriously affect dissipation rates, routes, and the extent of movement through soil profiles. The pesticide root zone model (PRZM) is designed to predict pesticide movement in unsaturated soils within and below the plant root zone in agricultural systems. The applicability of this model to a forested watershed was tested by using on-site hydrologic data to simulate a field application of lindane. PRZM-predicted data were compared with measured residue levels and found to estimate accurately lindane movement and leaching at shallow soil depths (0-10 cm), but underestimated residue levels at deeper soil depths (40-50 cm). Model simulations were used to evaluate various insecticide and herbicide application scenarios used in pine plantation management. Results from these simulations indicate that insecticides commonly used for gypsy moth (Lymantria dispar L.) or southern pine beetle (Dendroctonus frontalis Zimm.) control either are not sufficiently persistent or are adsorbed in the soil to such an extent that they do not pose a potential groundwater contamination problem. In contrast, site preparation herbicides show a potential to leach whenever proper meteorological conditions such as rainfall prevail after application. These herbicides are persistent (t1/2 &gt; 50), moderately adsorbed (10 &gt; Kd &gt; 0.1, assuming 1.7% organic matter), and applied under conditions of reduced evapotranspiration.
Comparison of FSCBG spray model predictions with field measurements
Authors: Rafferty James E. , Bowers James F. 
Published: March 2010

Abstract
The FSCBG (Forest Service, Cramer, Barry, and Grim) aerial spray model was developed under joint sponsorship of the U.S. Army and the USDA Forest Service to predict concentration, dosage, and deposition patterns of spray material downwind from aerial releases. A new version of the model incorporates the AGDISP model, which provides a much more rigorous mathematical description of wake effects on drop trajectories than the simple wake effects algorithm of the original FSCBG model. This paper describes graphical and statistical comparisons of deposition measurements from two field programs with model predictions using (a) no wake effects, (b) the simple wake effects of the original model, and (c) the AGDISP (agricultural dispersal) wake effects of the new model. All model versions showed skill in reproducing observed deposition profiles for both data sets. The inclusion of complex wake effects qualitatively improved the correspondence between predictions and measurements in the vicinity of the peak deposition for inwind releases and at the longer downwind distances for crosswind releases. However, statistical performance measures were inconclusive in quantifying this improvement.
Anaerobic dechlorination of aroclor 1242 as affected by some environmental conditions
Authors: Rhee G.-Yull , Bush B. , Sokol R.C. , Bethoney C.M. , DeNucci A. , Oh H.-M. 
Published: March 2010

Abstract
The effect of electron acceptors and biphenyl on reductive dechlorination was investigated using the commercial polychlorinated biphenyl mixture Aroclor 1242 and sediment microorganisms from the Hudson River. Polychlorinated biphenyl- (PCB-) free sediments spiked with the Aroclor at 700 μg/g and anaerobically incubated for six months, with and without biphenyl enrichment, showed that dechlorination was most advanced with CO2 without biphenyl enrichment. A small amount of methane was detected. However, methane production per se was not essential for dechlorination, because addition of the inhibitor of methane production, 2-bromoethane sulfonate, did not affect dechlorination. On the other hand, dechlorination was inhibited partly by sulfate and completely by nitrate. Biphenyl enrichment initially inhibited dechlorination under both methanogenic and sulfidogenic conditions.
Biotransformation of organophosphorus compounds by rainbow trout (Oncorhynchus mykiss) liver in relation to bioconcentration
Authors: De Bruijn Jack , Seinen Willem , Hermens Joop 
Published: March 2010

Abstract
Biotransformation of a series of organophosphorus compounds by the 9,000-g supernatant of rainbow trout (Oncorhynchus mykiss) liver was tested in an in vitro system fortified either with NADPH-generating cofactors or with reduced glutathione (GSH). Elimination rate constants for both systems were calculated from linear decay curves when substrate concentrations were used that were considerably lower than the Km values of the concerned enzymatic reactions. The results reveal a large variation in both the oxidative and the glutathione-mediated biotransformation rate of the organophosphorus compounds. Half-lives ranged from 25 to 1,216 min in the NADPH system and from 18 to 381 min in the GSH system. Elimination rate constants in the GSH system were related to Hammett σ constants or reactivity toward 4-nitrobenzylpyridine, which substantiates the assumption that electrophilicity is the controlling variable for the reaction with GSH within this particular class of compounds. A remarkable analogy was observed between compounds that were metabolized relatively quickly by glutathione S-transferases and compounds that showed a reduced bioconcentration factor in guppies. A significant improvement of the relationship between the bio-concentration factor in guppies and the octanol/water partition coefficient was obtained when the rate constant with GSH was introduced in this relationship. Such an improvement was not obtained with the rate constants from the oxidative system. These observations are discussed in view of the differences in the activities of the involved enzyme systems in the test species and in view of the possible relevance of the different biotransformation pathways for the in vivo situation.