bluuebunny/crossref_metadata_2025_split huggingface dataset:
Humic acid-modified silica as a model aquifer material
Authors: Burris David R. , Antworth Christopher P. , Stauffer Thomas B. , MacIntyre William G. 
Published: March 2010

Abstract
The sorption behavior of nonionic organic chemicals on humic acid-modified silica was examined to assess its possible use as a simplified model of natural low organic carbon aquifer materials. Column and batch sorption experiments were conducted on humic acid-coated silica (0.073% organic carbon), using tetrachloroethylene (PCE) and 1-methylnaphthalene (MN). Batch kinetic experiments showed that equilibrium was attained rapidly for PCE (˜1 d), whereas several tens of days were required for MN. Batch experiment results indicated Freundlich (nonlinear) isotherm behavior when a wide concentration range was examined. Sorption coefficients derived from the column experiments were consistent with the batch-derived Freundlich isotherms, illustrating the importance of isotherm type on breakthrough curves and solute transport in ground water. Similarities exist between the sorption behavior observed in this study and that of a number of natural aquifer materials. Humic acid-modified silica serves as a simplified model for aquifer materials, which tend to be more complex and difficult to characterize and can be used to examine organic solute transport processes in ground water.
Effects of alachlor and metolachlor on the biological activity of Azospirillum brasilense grown in chemically defined and dialyzed-soil media
Authors: Salmeron Victor , Martinez-Toledo Maria V. , Gonzalez-Lopez J. 
Published: March 2010

Abstract
The effects of 100, 300 and 500 μg/ml of alachlor and metolachlor were investigated in cells of Azospirillum brasilense grown in chemically defined medium and dialyzed-soil medium. Microorganisms cultured in the presence of alachlor showed lower nitrogenase activity and lower levels of ATP compared with control cells. However, the effects due to metolachlor disappeared after 48 h, showing that Azospirillum brasilense can tolerate high concentrations of that herbicide.
Toxicity tests of effluents with marsh plants in water and sediment
Authors: Walsh Gerald E. , Weber David E. , Simon Tasha L. , Brashers Linda K. 
Published: March 2010

Abstract
Methods are described for toxicity testing of water and sediment with two varieties of the freshwater marsh plant Echinochloa crusgalli (Linneaus) Palisot de Beauvois (Poaceae), and complex effluents. Two tests are described: a seed germination and early seedling growth test in water, and a survival and seedling growth test in natural and synthetic sediments. Effects of effluents from a sewage treatment plant, tannery, textile mill, pulp and paper mill, coking plant and sewage treatment plant included inhibition of germination, chlorophyll synthesis and growth. The tests with rooted marsh plants were sensitive to pollutants and detected toxicity of a range of pollutants in water and sediment. Synthetic sediments similar to natural sediments allowed toxicity tests to be done under carefully controlled conditions of particle size distribution, organic content, pH, electrode potential (Eh) and cation exchange capacity (CEC).
Effects of methyl parathion on northern bobwhite survivability
Authors: Buerger Theodore T. , Kendall Ronald J. , Mueller Brad S. , Devos Theodore , Williams Bill A. 
Published: March 2010

Abstract
The effects of methyl parathion on survivability of wild northern bobwhites (Colinus virginianus) were investigated from 1986 to 1988 near Tallahassee, Florida. In three field seasons, 197 bobwhites were administered 0, 2, 4 or 6 mg/kg methyl parathion in corn oil by oral intubation, released and monitored for 14 d using radio telemetry. Bobwhites receiving 6 mg/kg methyl parathion had lower survival (P = 0.022) than control birds due to predation, not overt toxicity. There were no differences (P &gt; 0.05) among treatment groups in activity, but methyl parathion may have influenced covey integrity. Birds that survived methyl parathion treatment had brain cholinesterase activities similar to those of control bobwhites. The results suggest that if bobwhites receive sufficiently high methyl parathion exposure in their natural habitats, then their susceptibility to predation may increase.
Bioassays for the toxicity of petroleum oils in chicken embryos
Authors: Couillard Catherine M. , Leighton Frederick A. 
Published: March 2010

AbstractApplications of 1 μl to 30 μl of six different petroleum oils were made to the shell of fertile leghorn chicken eggs on day 9 of incubation. Mortality and grossly visible morphological changes in the embryos were evaluated 4 d after treatment. South Louisiana crude oil and fuel oil No. 2 were the less toxic of the oils tested, with LD25s of 14.1 and 8.5 μl/egg. The LD25s of Arabian Light, Federated, Norman Wells and Prudhoe Bay crude oils ranged from 3.6 to 4.4 μl/egg. Liver necrosis and edema were found in embryos exposed to the six petroleum oils, suggesting a common mechanism of toxic action. The similarity in mechanism of action was also supported by the similarity of the slopes of the dose-response lines. The use of liver necrosis as an end point for bioassays of oil toxicity was evaluated. The ED25s ranged from 3.6 μl/egg for Federated crude oil to 23.0 μl/egg for fuel oil No. 2. Estimates of the ED25 for liver necrosis could discriminate among the toxicity of the six oils better than could estimates of the LD25 test. There was a good correlation between the two calculations. The ED25 was more reliable and consistent than the LD25 test when bioassays were repeated several times with the same oil.
Leaching potential and decomposition of clopyralid in Swedish soils under field conditions
Authors: Bergström L. , McGibbon A. , Day S. , Snel M. 
Published: March 2010

Abstract
The mobility and decomposition of the herbicide clopyralid (3,6-dichloro-2-pyridinecar-boxylic acid) were studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile-drained plots (clay). Soil samples were also collected down to 1 m depth in both soils to characterize the temporal depth distribution of clopyralid in the profiles. The herbicide was applied at two rates, i.e., 120 and 240 g acid equivalents (a.e.)/ha, representing normal and double doses of the compound for sugar beets and oilseed rape. Some lysimeters received supplementary watering. Concentrations of clopyralid above the detection limit {0.4μg/L}, i.e., 0.5 (normal dose) and 6 μg/L (double dose) were found in only two drainage samples from the clay soil. Both samples were collected simultaneously approximately two months after the herbicide application, by which time less than 1 mm of drainage had been collected. The overwhelming part of applied clopyralid remained in the topsoil at both sites. Four months after spraying, no clopyralid was detectable (&lt;2 μg/kg dry soil) in the soil.
Mobility and dissipation studies of metribuzin, atrazine and their metabolites in plainfield sand using field lysimeters
Authors: Bowman Bruce T. 
Published: March 2010

Abstract
Mobility and persistence of metribuzin (Lexone DF) and its metabolites (deaminated, DA; diketo, DK; deaminated-diketo, DADK) were studied using 75-cm × 15-cm field lysimeters packed with Plainfield sand, and subjected to two moisture regimes (rainfall, supplementary watering). Atrazine was applied to all lysimeters as an internal reference. Each lysimeter set consisted of 24 lysimeters, divided into two moisture treatments of six pairs each. Effluent was monitored for metribuzin, DA, DK, DADK, atrazine and desethylatrazine. Selected core pairs were sectioned (7 × 10 cm) and analyzed to determine mobility and persistence for each chemical at weeks 1, 2, 4, 8, 12, and 21. No chemicals moved more than 30 cm, nor were they detected in the effluent of cores receiving rainfall. In cores receiving supplementary watering, substantial amounts of metribuzin moved more than 30 cm by week 2 and eluted on 21 occasions throughout the study. The DADK and DK were much more mobile than metribuzin in the lysimeters, eluting more frequently than metribuzin. Metribuzin and metabolites were considerably more mobile than either atrazine or desethylatrazine in Plainfield sand. Metribuzin disappearance closely followed first-order kinetics with t1/2 values of 3.08 and 2.04 weeks, respectively, for the rainfall and supplementary watering treatments. The primary degradation pathway for metribuzin was through the DK intermediate rather than the DA intermediate.
A strategy for ranking environmentally occurring chemicals. Part V: The development of two genotoxicity QSARs for halogenated aliphatics
Authors: Eriksson Lennart , Jonsson Jörgen , Hellberg Sven , Lindgren Fredrik , Sjöström Michael , Wold Svante , Sandström Björn E. , Svensson Indra 
Published: March 2010

Abstract
A strategy for systematic analysis and priority ranking of chemicals was applied to a class of 58 saturated halogenated aliphatics. The training set, selected by statistical design, was subjected to biological testing in an assay (the DNA precipitation assay) estimating DNA damage in V79 Chinese hamster cells. The obtained genotoxicity data were modeled by construction of two multivariate quantitative structure-activity relationships (QSARs). To experimentally validate the two derived QSAR models, a validation set of chemicals was chosen (also according to statistical design). Predictions were made for the validation set compounds, and they were found to compare well with the observed data. Thus, the two QSARs were utilized to predict the genotoxicity of 36 nontested compounds belonging to the examined class. In addition, it was found that the genotoxicity data required a multitude of chemical and structural descriptors in order to be modelable, and that log P in particular was an informative descriptor variable.
Aqueous solubility of liquid hydrocarbon mixtures containing dissolved solid components
Authors: Vadas George G. , MacIntyre William G. , Burris David R. 
Published: March 2010

Abstract
Two hypothetical supercooled liquid (HSL) solubility estimation methods are evaluated for 11 solid polynuclear aromatic hydrocarbons (PAHs). The HSL solubility is required to estimate the aqueous solubility of solids such as PAHs when they are part of a liquid hydrocarbon mixture. Aqueous solubility experimental data for binary and multicomponent liquid hydrocarbon mixtures containing PAHs were used to evaluate the HSL solubility estimation methods. An HSL solubility estimation method requiring only the component's pure compound solubility and melting point proved to be adequate for most environmental applications.
Predicting chemical accumulation in shoots of aquatic plants
Authors: Wolf Sue D. , Wooten Steven E. , Lassiter Ray R. 
Published: March 2010

Abstract
Chemical exchange dynamics expected for diffusive transfer of a chemical between aqueous solution and plant shoots, and expected bioconcentration based on partitioning properties of the chemical, are explored by using a three—compartment model. The model utilizes three dynamic compartments-leaves, stems, and aqueous exposure medium. Chemical mass flux is dependent on the morphometry of the plant species, on exposure concentration, and on partitioning character of the chemical. The steady-state bioconcentration factor (KSH) is dependent on composition of the plant species and partitioning character of the chemical. The model was parameterized for three species of aquatic plants (Myriophyllum spicatum, Bacopa caroliniana, and Hydrilla verticillata) and two chlorinated benzenes (1,2,3,4-tetrachlorobenzene [TCB] and 1,2-dichlorobenzene [DCB]). Predictions of uptake and bioconcentration are compared to results of static laboratory studies conducted with whole shoots of the three species over exposure periods ranging from 1 h to 21 d. Predicted tissue burdens and Ksh values are generally within one standard deviation of measured values. Shoots approach steady-state tissue burdens between 1 and 3 d after initial exposure. Ksh values for TCB (360-750), the more hydrophobic chemical, are at least an order of magnitude greater than those measured for DCB (11-28).
Humans are a sensitive species to some of the biochemical effects of structural analogs of dioxin
Authors: Lucier George W. 
Published: March 2010

AbstractIn 1979, rice oil contaminated with polychlorinated dibenzofurans (PCDFs) was ingested in a widespread poisoning episode in Taiwan. The PCDFs are structural analogs of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD and the PCDFs are thought to share the same mechanism of action that involves binding to the Ah receptor. In our studies, we compared the effects of TCDD on rat liver to effects in placentas of women exposed to PCDF-contaminated rice oil. TCDD is a hepatocarcinogen in female rats. Measured parameters included concentrations of human placental PCDF congeners or rat liver TCDD and induction of cytochrome P-450 isozymes, epidermal growth factor receptor (EGFR) and glucocorticoid receptor (GCR). Placentas from PCDF-exposed women contained two PCDFs: 2,3,4,7,8-penta CDF (100 ppt) and 1,2,3,4,7,8-hexa CDF (400 ppt). The 2,3,4,7,8-penta CDF binds the Ah receptor 60% as well as TCDD, and the 1,2,4,7,8-hexa CDF binds 9% as well as TCDD. Cytochrome P1-450 was induced approximately 100-fold in exposed placentas. This induction was considered maximal. Placental PCDF concentrations associated with this induction were compared to the amount of hepatic TCDD required to maximally induce the rat liver homolog of P1-450. These comparisons, accounting for differences in Ah receptor binding, suggested that humans are more sensitive than rats to the P1-450 inductive actions of the toxic halogenated aromatics. Several assumptions are made, and their validity is discussed. As with the P1-450, humans are more sensitive to the effects of the halogenated aromatics on EGFR (EGF-stimulated autophosphorylation) and GCR (binding capacity) than are rats. Although the relationship of these biochemical changes to the carcinogenic effects of TCDD and its analogs is not clear, our data suggest that it is prudent to retain a conservative risk assessment for the toxic halogenated aromatics.
The toxic effects of pollutants on the mineralization of acetate in subsoil microcosms
Authors: van Beelen P. , Fleuren-Kemilä A. K. , Huys M. P. A. , van Montforta A. C. P. , van Vlaardingen P. L. A. 
Published: March 2010

Abstract
The mineralization of [14C]acetate or [14C]glucose was studied in aseptic subsoil samples at 10°C. At 1 μg/L and 100 μg/L, the mineralization showed first-order kinetics preceded by a short lag phase. For the sandy subsurface soils, the half-lives of acetate or glucose varied from 0.5 until 21 d, whereas a peat subsoil and a sandy surface soil produced half-lives of 11 and 1.6 h, respectively.
The EC50 is the toxicant concentration that causes 50% reduction of the percentage substrate mineralized at a certain incubation time and increases with time. The time-independent toxicant concentration IC50 gives 50% inhibition of the mineralization rate and is equal to the EC50 at short incubation times. The IC50 of pentachlorophenol varied between 0.1 and 880 mg/kg subsoil. The aerobic mineralization of acetate in surface sand showed an IC50 of 28 mg pentachlorophenol/kg. Hydrochloric acid showed IC50 values ranging from pH 6.2 to pH 2.8. For chlorite and cadmium, the IC50 values were 34 and 59 mg/kg, respectively.
When soils were incubated with 100 mg acetate/L, exponential growth kinetics were observed. Under these conditions the inhibitory effect of pentachlorophenol was relatively small because the resistant part of the acetate-mineralizing microflora could grow and replace the inhibited part. The kinetics show why toxicity tests using high substrate concentrations are less sensitive than tests using more natural low substrate concentrations. The model predicts that slow-growing microorganisms, which are vital to the functioning of the ecosystem, would recover only very slowly from the toxic effects of environmental pollution.
Uptake and elimination kinetics of organophosphorous pesticides in the guppy(poecilia reticulata): Correlations with the octanol/water partition coefficient
Authors: de Bruijn Jack , Hermens Joop 
Published: March 2010

AbstractBioconcentration factors, uptake rate constants and elimination rate constants of a series of organophosphorous pesticides were determined in the guppy (Poecilia reticulata). The results of these three toxicokinetic parameters were related to measured octanol/water partition coefficients (Kow). A simple one-compartment model fitted the uptake and elimination characteristics of the chemicals. A biphasic relationship was observed between log k1 (uptake rate constant) and log Kow, whereas elimination rate constants were inversely related to Kow. For some of the test compounds substantially higher elimination rates were found, compared to isolipophilic chlorobenzenes, which resulted in lower bioconcentration factors. This divergent behavior is discussed in view of possible biotransformation reactions for these compounds.
Assessment of methods for estimating aquatic hazards at superfund-type sites: A cautionary tale
Authors: Burmaster David E. , Menzie Charles A. , Freshman Jonathan S. , Burris Janet A. , Maxwell Nancy Irwin , Drew Scott R. 
Published: March 2010

Abstract
Field studies, laboratory experiments and theoretical calculations were used to estimate the ecological risk caused by the release of toxic organic compounds from the Baird and McGuire Superfund hazardous waste site to the Cochato River, a small river in eastern Massachusetts. The results from the field studies, which included (a) direct measurements of chemical concentrations in sediments and fish tissues; (b) direct measurements of chemical concentrations in dialysis bags filled with hexane and placed in the river; and (c) taxonomic surveys at stations upstream of, adjacent to and downstream of the site, were compared to the results from laboratory tests and computer models, which included (d) toxicity bioassays, (e) toxicity quotients based on the U.S. Environmental Protection Agency's interim sediment quality criteria, and (f) estimates of bioaccumulation using equilibrium and fugacity models. The resulting patchwork of confirmatory and contradictory findings highlights the limitations of available theoretical and laboratory methods and cautions against reliance on any single method of quantifying stress to aquatic ecosystems.
Fate of the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (rdx) in soil and bioaccumulation in bush bean hydroponic plants
Authors: Harvey Scott D. , Fellows Robert J. , Cataldo Dominic A. , Bean Roger M. 
Published: March 2010

Abstract
Soils amended with [14C]hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were sampled over 60 d and subjected to exhaustive Soxhlet extraction followed by HPLC analysis. RDX was the only radiolabeled compound observed in soil extracts. Emission of volatile organics and 14CO2 from soil accounted for only 0.31% of the amended radiolabel. Mass balance for RDX-amended soil was better than 84% throughout the two-month study. The analytical method developed for plants involved acid hydrolysis, solvent extraction, fractionation on Florisil® adsorbent and separation by HPLC. The described methodology allowed for RDX recovery of 86 ± 3% from fortified bush bean leaf tissue. Further experiments were conducted with bush bean plants maintained on RDX-containing hydroponic solutions. Hydroponic plants did not emit detectable amounts of 14CO2 or radiolabeled volatile organics. Analysis of the plant tissue indicated bioaccumulation of RDX in the aerial tissues of hydroponic plants exposed for either 1 or 7 d. Metabolism of RDX to polar metabolites was observed in plants exposed for 7 d.
Application of toxicity identification evaluation procedures to the ambient waters of the colusa basin drain, California
Authors: Norberg-King Teresa J. , Durhan Elizabeth J. , Ankley Gerald T. , Robert Eric 
Published: March 2010

AbstractPesticides are applied to the rice fields in the Sacramento Valley to prevent the growth of plants, algae and insects that reduce rice yields. Following the pesticide application, field water is released into agricultural drains that in turn discharge into the Sacramento River and delta. Rice irrigation is the largest single use of irrigation water in the Sacramento Valley, and because the irrigation water (or rice return) flows are the primary source of drain effluent during the spring and summer (up to 33% of the total flow), these discharges can significantly affect drain water quality and resident aquatic organisms. Acute and chronic toxicity to freshwater organisms (Ceriodaphnia dubia) was observed in the drain water during the period that coincides with the initial draining of the fields in 1986, 1987 and 1988. In 1988, a toxicity identification evaluation (TIE) was conducted using Ceriodaphnia dubia in an effort to identify the cause of toxicity. Both methyl parathion and carbofuran were identified as possible toxicants. Mixture tests and chronic toxicity tests indicated that the concentrations of methyl parathion and carbofuran in the water sample account for the toxicity observed in Ceriodaphnia dubia.
Effects of dietary boron and arsenic on the behavior of mallard ducklings
Authors: Whitworth Molly R. , Pendleton Grey W. , Hoffman David J. , Camardese Michael B. 
Published: March 2010

Abstract
High concentrations of boron and arsenic have been associated with irrigation drain water and aquatic plants consumed by waterfowl. Both compounds affect the central nervous system and cause generalized physiological distress in mammals and waterfowl. We examined sublethal effects of boron and arsenic on the behavior of developing mallard ducklings (Anas platyrhynchos). Day-old ducklings received an untreated diet (control) or a diet containing 100, 400, or 1,600 ppm boron, added as boric acid, or 30, 100, or 300 ppm arsenic, added as sodium arsenate. Activity schedules and behavior durations were analyzed for effects at the various treatment levels. Both boron and arsenic at the highest levels had significant effects on the activity schedules of developing ducklings, including increased time at rest and under the provided heat lamp. We also observed decreases in the amount of time treated ducklings spent in alert behaviors and in the water in comparison to control ducklings. High levels of boron (1,600 ppm) increased feeding time overall but did not increase the amount of food consumed. Arsenic had no effect on feeding behavior. There were no differences found in the durations of behaviors as a result of treatment. These findings, in combination with reported effects on the growth and physiology of ducklings under identical treatments, suggest that reported concentrations of these compounds in aquatic plants in the Central Valley of California could adversely affect normal duckling development and survival.