bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of water temperature and pH on toxicity of terbufos, trichlorfon, 4-nitrophenol and 2,4-dinitrophenol to the amphipod Gammarus pseudolimnaeus and rainbow trout (Oncorhynchus mykiss)
Authors: Howe George E. , Marking Leif L. , Bills Terry D. , Rach Jeffery J. , Mayer Foster L. 
Published: March 2010

Abstract
Acute toxicity tests were conducted to determine (a) the individual and interactive effects of water temperature (7, 12, 17°C), pH (6 5, 7 5, 8 5, 9 5), and time on the toxicity of terbufos, trichlorfon, 4 nitrophenol, and 2,4-dinitrophenol to rainbow trout (Oncorhynchus mykiss) and the amphipod Gammarus pseudohmnaeus, and (b) the individual and interactive effects of water temperature and pH on chemical bioconcentration during acute tests with rainbow trout and Gammarus exposed to terbufos, 4 nitrophenol, and 2,4 dinitrophenol The toxicity of all four chemicals was significantly affected by pH in all tests, except for Gammarus exposed to terbufos The toxicity of terbufos to rainbow trout and Gammarus was less at pH 7 5 than at higher or lower pH The toxicity of both nitrophenols decreased as pH increased, whereas the toxicity of trichlorfon increased with pH The effect of pH on trichlorfon toxicity decreased with temperature Temperature significantly affected the toxicity of all four chemicals to both species Toxicity increased with temperature in all tests, except for rainbow trout exposed to nitrophenols, toxicity decreased as temperature increased for rainbow trout Chemical bioconcentration was also significantly af fected by temperature and pH and was directly related to toxicity in most tests Significant interactive effects between toxicity modifying factors were also frequently observed Temperature and pH effects on chemical toxicity need to be consid ered in chemical hazard assessment to ensure adequate protection of aquatic organisms
Toxicity of carbaryl and malathion to two federally endangered fishes, as estimated by regression and Anova
Authors: Beyers Daniel W. , Carlson Clarence A. , Keefe Thomas J. 
Published: March 2010

Abstract
Toxicity of technical carbaryl, Sevin®-4-Oil, and technical malathion to federally endangered Colorado squawfish (Ptychocheilus lucius) and bonytail (Gila elegans) was estimated by 4-d renewal-acute and 32-d early life-stage (ELS) tests. Median lethal concentrations were estimated by probit analysis. Effect concentrations for ELS tests were estimated by ANOVA and an alternative procedure using a linear-plateau regression model. Linear-plateau regression estimated a threshold concentration above which toxic effects began to occur. Median lethal concentrations and 95% confidence limits (in parentheses) for carbaryl, Sevin-4-Oil, and malathion were 1.31 (1.23, 1.40), 3.18 (2.87, 3.52), and 9.14 mg/L (8.36, 10.0) for Colorado squawfish and 2.02 (1.78, 2.25), 3.31 (3.06, 3.55), and 15.3 mg/L (14.4, 16.4) for bonytail. NOECs for Colorado squawfish were 445 μg/L carbaryl and 1,680 μg/L malathion. The NOECs for bonytail were 650 μg/L carbaryl and 990 μg/L malathion. Threshold concentrations for Colorado squawfish in ELS tests were 364 μg/L carbaryl and 455 μg/L malathion. Threshold concentrations for bonytail were 217 μg/L carbaryl and 521 μg/L malathion. Estimates of effect concentrations from linear-plateau regression were consistently lower than those estimated by hypothesis testing. Linear-plateau regression models accounted for a significant amount of total variation and adequately described the observed concentration-response relation.
PCB and DDE methyl sulfones in mammals from Canada and Sweden
Authors: Bergman Åke , Kuroki Hiroaki , Norstrom Ross J. , Haraguchi Koichi , Béland Pierre 
Published: March 2010

AbstractLevels of PCB methyl sulfones (MeSO2-CBs) and DDE methyl sulfones (MeSO2-DDEs) have been determined in tissues from polar bear (Ursus martimus), beluga whale (Delphinapterus leucas), and false killer whale (Pseudorca crassidens) from the Canadian environment, and grey seal (Halichoerus grypus), otter (Lutra lutra), and wild mink (Mustela vison) from the Swedish environment. Up to 30 MeSO2-CB congeners and three MeSO2-DDE isomers were shown to be present in the analyzed tissues. The concentration of total MeSO2-CBs ranged from 0.1 to 21 μg/g extracted lipids. 3-MeSO2-2,5,2′,4′,5′-penta-CB is the dominating MeSO2-CB congener in all the analyzed samples, but the corresponding 4-MeSO2-CB also is present in high concentrations. A smaller number of MeSO2-CBs, always dominated by the meta-substituted MeSO2-CBs, were present in livers of grey seal, otter, and mink than in adipose tissue or muscle. In all studied mammals the concentrations of MeSO2-CBs were higher in liver than in blubber or muscle. Seven PCB congeners were identified as precursors of the PCB methyl sulfones: 2,4,2′,5′-tetra-CB (CB-49), 2,5,3′,4′-tetra-CB (CB-70), 2,4,5,2′,5′-penta-CB (CB-101), 2,3,4,5,2′,5′-penta-CB (CB-87), 2,3,6,2′,4′,5′-hexa-CB (CB-149), 2,3,4,2′,3′,6′-hexa-CB (CB-132), and 2,3,4,2′,5′-hexa-CB (CB-141). All species except beluga whale contained 3-MeSO2-4,4′-DDE, but at a much lower concentration in mink and otter than in the other mammals. Polar bear and grey seal liver also contained 2-MeSO2-4,4′-DDE. The concentrations of 2- and 3-MeSO2-DDE ranged from 0.01 to 1.3 μg/g extracted lipids. A hitherto unknown MeSO2-DDE isomer was determined in false killer whale blubber by GC-MS, along with 2- and 3-MeSO2-4,4′-DDE and several unknown MeSO2-penta-CBs and MeSO2-hexa-CBs. tris(4-chlorophenyl)methanol was identified in the aryl methyl sulfone fraction of polar bear liver and grey seal blubber samples.
Chemical and biological 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in fly ash from combustion of bleached kraft pulp mill sludge
Authors: Kopponen Päivi , Törrönen Riitta , Välttilä Olli , Talka Esko , Tarhanen Juhani , Ruuskanen Juhani , Kärenlampi Sirpa 
Published: March 2010

Abstract
Fly ash was collected from five large-scale or pilot tests in which burning of bleached kraft pulp mill sludge was studied. The content of dioxin-like compounds in this fly ash was estimated both chemically and biologically. Fly ash was analyzed chemically for 17 PCDD and PCDF congeners by high-resolution GC-MS, and the data were transformed to Nordic TCDD equivalents. The biological analyses were based on the induction of several enzymes (aryl hydrocarbon hydroxylase [AHH], 7-ethoxyresorufin O-deethylase [EROD], aldehyde dehydrogenase-3 [ALDG3]) by the fly ash extracts in a mouse hepatoma cell line, Hepa-1. The inducing potencies were expressed as biological TCDD equivalents. There was a good correlation between the Nordic and the biological TCDD equivalents. Differences in the amounts of dioxin-like compounds among the combustions were attributed mainly to the boiler types and not to fuel characteristics or combustion parameters.
New quantitative approach for analysis of binary toxic mixtures
Authors: Haas Charles N. , Stirling Bruce A. 
Published: March 2010

AbstractHumans generally are exposed simultaneously to a number of toxins, including complex mixtures of unknown and variable origin. Although procedures for assessing the potential toxic risks associated with exposure to individual chemicals are relatively well established, methods for assessing the risks of complex mixtures are still in the developmental stages. One source of considerable uncertainty in these estimates is the potential for interaction among chemicals in complex mixtures. The objective of this work was to gain a better understanding of the effects posed by toxicant interactions and to test a new approach for analyzing the dose-response effects of binary toxic mixtures. This new method of analysis enables a more rapid and quantitative assessment of the interactive effects of pairs of toxic chemicals. A number of experimental studies showing multicompo-nent toxicity were tested using the proposed approach. Both positive and negative interactions of the toxicants were documented for these studies, with significantly acceptable predictive capabilities observed for the model.
Chemical fate and transport in a domestic septic system: Sorption and transport of anionic and cationic surfactants
Authors: McAvoy D.C. , White C.E. , Moore B.L. , Rapaport R.A. 
Published: March 2010

Abstract
The sorption and transport of linear alkylbenzene sulfonate (LAS) and dialkyl quaternary ammonium compounds [ditallow dimethyl ammonium chloride (DTDMAC) and distearyl dimethyl ammonium chloride (DSDMAC)] were determined within the upper soil horizons and in the aquifer below a septic tank tile field at a study site in Ontario. Sorption of LAS was greatest immediately below the tile field (Kd = 17 L/kg) within the upper unsaturated soil horizons and lowest in the aquifer (Kd = 1 L/kg). LAS sorption appeared to be controlled by a hydrophobic mechanism and was positively correlated with the organic carbon (r = 0.9) and the clay content (r = 0.9) in the subsurface environment. The sorption of DTDMAC/DSDMAC (Kd = 25-62 L/kg) was an order of magnitude higher than LAS but showed no trend throughout the subsurface environment. The retention of DTDMAC/DSDMAC was believed to be by ion exchange within the clay interlayer basal spaces. Samples collected from the field showed concentrations of DTDMAC to range from approximately 60 mg/kg in the tile field gravel to &lt;2 mg/kg within 10 cm of soil below the tile field gravel. Concentrations of LAS were approximately 20 mg/kg in the tile field gravel and diminished to &lt; 1 mg/kg within 5 cm of soil below the tile field gravel. Soil solution and aquifer concentrations of LAS were always &lt;50 μg/L and usually below the detection limit of 10 μg/L in the aquifer. Concentrations of DTDMAC in the aquifer were below the limit of detection (4 μg/L). Mathematical calculations illustrated the importance of biodegradation and sorption as removal mechanisms of these materials in subsurface environments.
Chemical fate and transport in a domestic septic system: Application of a variably saturated model for chemical movement
Authors: Shutter S.B. , Sudicky E.A. , Robertson W.D. 
Published: March 2010

Abstract
A detailed mathematical modeling study of the impact of a single-family septic system on groundwater quality is described. The work served to improve the conceptual understanding of subsurface processes associated with septic systems and lent insight into the fate of septic-system-derived chemicals. Two-dimensional saturated-unsaturated simulations of the chemical plume associated with the septic system were successful in closely matching field observations. Results indicate that the plume has been subject to limited dispersion (or spreading) reflecting the homogeneous nature of the aquifer materials. The sharp concentration gradients along the upper fringe of the plume near the watei table indicate weak vertical mixing and imply limited dilution by recharge water entering the aquifer downgradient of the septic system. Calibrated dispersivities were 10 cm for the longitudinal value (αL) and 1 mm for the transverse vertical value (αT). The movement of reactive chemical constituents present m consumer detergent products entering the septic system was simulated to assess the influence of sorption and biodegrada-tion. The migration of the detergent compounds linear alkylbenzene sulfonate (LAS) and nitrilotriacetic acid (NTA) was found to be controlled mainly by these processes, and the limited movement predicted by the model is consistent with that observed in the field. For a half-life equal to 15 d and a distribution coefficient (Kd) value equal to 1.5 L/kg in the unsaturated zone, LAS was predicted to move &lt;0.5 m from the tile drains. However, chemicals having a significantly longer half-life or those which exhibit limited partitioning to the soil matrix are likely to migrate much further.
Biodehalogenation: Rapid oxidative metabolism of mono- and polyhalomethanes by Methylosinus trichosporium OB-3b
Authors: Bartnicki E.W. , Castro C.E. 
Published: March 2010

Abstract
Resting cells of Methylosinus trichosporium OB-3b grown in the absence of copper salts rapidly oxidize mono- and polyhalomethanes. The order of reactivity of the series is CH3X &gt; CH2X2 ≥ CHX3 (X = CI, Br). Based on halide ion release, the half-life for methyl bromide and methyl chloride is 9.4 min with a cell density of 0.1 g/ml. The dihalomethanes and bromo-form react at the same rate and half as rapidly as the methyl halides. Chloroform is converted to carbon dioxide at one-fourth the methyl halide rate (t1/2 = 38 min). No isotope effect was observed with either deuteromethylene chloride or deuterochloro-form (CD2Cl2, CDCl3). In all cases, the dehalogenation chemically follows an oxygen insertion into the CH bond, and the final product is carbon dioxide (HCO3−). All reactions are inhibited by acetylene, establishing methane monooxygenase as the responsible enzyme. Incubations with 13CHCl3, 13CH2Br2, and 13CH3Br and nuclear magnetic resonance (NMR) analysis of reaction mixtures showed the first hydrolytically stable products from CHCl3 (HCO3−) and CH2Br2 (CO), but neither formaldehyde nor formate could be detected as intermediates with methyl bromide by this method. The oxidative destruction of halo-methanes by this methylotroph is rapid and not very sensitive to structure.
Effects of freshwater petroleum contamination on amphibian hatching and metamorphosis
Authors: Mahaney Patricia Ann 
Published: March 2010

AbstractThis study examined the effects of freshwater petroleum contamination on amphibian reproduction The primary objectives were to assess the potential environmental and physiological impacts of runoff petroleum products on amphibians, using the green treefrog (Hyla cinerea) as a target species and engine crankcase oil as a contaminant Egg hatching success, tadpole growth, and successful metamorphosis were measured in four concentrations of oil The effects of oil on food source was also studied Hatching success was not measurably influenced by the presence of oil Tadpole and alga growth were negatively associated with the presence of oil No tadpoles from the high concentration of oil treatments successfully metamorphosed
Effects of fenitrothion on memory for cache-site locations in black-capped chickadees
Authors: Mineau Pierre , Boag Peter T. , Beninger Richard J. 
Published: March 2010

Abstract
The effect of femtrothion on food caching in the black-capped chickadee was investigated Oral doses of femtro-thion calculated to produce peak brain inhibition levels of 50 to 60% had no effect, or possibly even improved the ability of the birds to retrieve existing food cache memories when administered after cache locations had been memorized In the more extreme cases, birds were able to remember cache sites even when their physical abilities were still visibly impaired The same dose of femtrothion administered to the birds before they were allowed to cache improved cache-recovery performance This result is consistent with results we obtained at lower brain ChE inhibition levels with physostigmine (reported elsewhere) It is inconsistent with studies that indicate that dosing with anti ChEs typically gives rise to a U-shaped response with impairment at the higher dose levels
Rat liver mitochondrial and microsomal tests for the assessment of quinone toxicity
Authors: Bramble Lisa A , Boardman Gregory D , Dietrich Andrea M. , Bevan David R 
Published: March 2010

AbstractShort term toxicity tests using mitochondrial and microsomal metabolism were developed and applied to a series of eight quinones In the mitochondrial assay, the degree to which test compounds inhibited mitochondrial respiration varied from an effective concentration (EC50) of 9 to 125 μM In the microsomal assay, the maximum percentage of increase over control oxygen consumption rates elicited by the quinones ranged from 8 to 837% The ability of the compounds to stimulate microsomal oxygen uptake reflects their capability to redox cycle and form reactive oxygen species Results of the mitochondrial and microsomal assay were statistically correlated with several quinone physicochemical parameters and qualitatively compared to reduction potential The biological response observed in both test systems appeared to be most strongly influenced by the re duction potential of the quinone Biomechanisms of action were suggested on the basis of this relationship To assess the abil lty of the mitochondrial and microsomal assays to indicate toxicity of the quinonoid compounds, results were statistically correlated with literature derived toxicity data It was concluded that the mitochondrial assay appears to be a valid indicator of acute tox lcity, whereas the microsomal assay better portends the potential for chronic toxicity
Effects of three pesticides on Poecilus cupreus (coleoptera: carabidae) at different post-treatment temperatures
Authors: Heimbach U. , Baloch A A 
Published: March 2010

Abstract
The influence of post-treatment temperatures of 5, 10, 17 5, and 25°C on the efficacy of three pesticides, Karate (10 g a i/ha lambda cyhalothnn), Sumicidin 10 (30 g a i/ha fenvalerate), and Afugan (294 g a i/ha pyrazophos), applied to Poecilus cupreus (Coleoptera Carabidae) was investigated in the laboratory The results indicate a negative correlation between the temperature and the effects of all three products With the two pyrethroids Karate and Sumicidin, the recovery period of knocked down beetles and their food consumption showed this negative temperature correlation The reason seems to be a temporarily arrested detoxification of the pyrethroids inside the beetles at reduced temperatures Final mortality seven weeks after application of pyrethroids was unaffected by temperature With the organophosphorus compound pyrazophos final mortality was negatively correlated with temperature Male beetles seemed to be more sensitive than females with all products and temperatures
Toxicity and metabolism of 2,4-dichlorophenol by the aquatic angiosperm Lemna gibba
Authors: Ensley Harry E. , Barber John T. , Polito Michael A. , Oliver Ana I. 
Published: March 2010

Abstract
The toxicity and metabolism of 2,4-dichlorophenol, with regard to the aquatic macrophyte Lemna gibba (duckweed), have been studied Toxicity is described in terms of the effect of 2,4-dichlorophenol (2,4-DCP) on the vegetative reproduction of duckweed over a 10-d growth period, the EC10 and EC50 were 2.5 and 9 2 μM, respectively. Metabolism of 2,4-dichlorophenol was monitored by incubation of the plants with radiolabeled substrate, and periodic sampling and analysis by reversed-phase HPLC of the plant growth medium Depending on the growth conditions, up to 95% of the 2,4-DCP was metabolized over a 6-d growth period. To analyze the metabolites, the plants were grown in the presence of sublethal concentrations of [U-14C]-2,4-DCP. The growth medium was lyophihzed and then mixed with the plants, extracted, and analyzed using reversed-phase HPLC, followed by scintillation counting of the fractions The major metabolite was isolated and identified as 2,4-dichlo-rophenyl-β-D-glucopyranoside by high-field NMR and MS. The structure of the metabolite was confirmed by synthesis and by enzymatic cleavage of the β-glucosidic linkage to afford 2,4-DCP. An important consequence of conjugate formation is the masking of the presence of 2,4-DCP to the usual analytical techniques used for its detection and quantitation. This finding is probably applicable to other contaminants and organisms.
Interaction of toxicants and communities: The role of nutrients
Authors: Lozano R. Barreiro , Pratt J.R. 
Published: March 2010

Abstract
The interaction between community nutrient status and toxicity was studied in laboratory microcosms containing natural periphyton communities The three experimental nutrient treatments (low, medium, high) increased by orders of mag nitude from 0 05 mg N per liter + 0 01 mg P per liter Communities were developed with nutrient treatments for 25 d and were then exposed to 3 5 mg/L diquat, a photosynthetic inhibitor, and studied for an additional 23 d The effects of toxicant addi tion were assessed by measuring changes in biomass (protein, chlorophyll), enzyme activity (alkaline phosphatase electron trans port), nutrient release, diurnal changes in microcosm oxygen (gross productivity), and toxicant fate The rate of diquat loss was lowest in the low nutrient treatment Gross photosynthesis was nearly eliminated by diquat in the low nutrient treatment and showed limited recovery Productivities in the medium and high nutrient treatments were equivalent and showed evidence of both effect (approximately 50% reduction) and recovery Protein biomass was reduced in low nutrient microcosms treated with diquat, but no effect on chlorophyll biomass was observed Diquat inhibited respiratory electron transport activity, and mi crocosms with low nutrient availability had limited ability to recover from the diquat stress These studies suggest that commu nity nutrient status affects both the magnitude of effect and the rate of recovery of processes following stress
Stream microcosm toxicity tests: Predicting the effects of fenvalerate on riffle insect communities
Authors: Breneman Dan H. , Pontasch Kurt W. 
Published: March 2010

Abstract
Stream microcosms were used to predict toxicity of the pyrethroid insecticide fenvalerate to riffle insect assemblages. Over a 30-d test period, stream microcosms were exposed in triplicate to 0.0, 0.01, 0.1, 1.0, or 10.0 μg/L fenvalerate. Effects were determined by statistically comparing insect abundances over all concentrations. Initial exposure resulted in a significant increase in drift in the 1.0- and 10.0-μg/L treatments. After 30 d, several taxa exhibited density reductions at 0.01 μg/L, but this reduction was significant for only one taxon. Densities of most other taxa decreased significantly at 0.1 μ/L. Significant reductions in species richness and total density also were observed at 0.1 μg/L fenvalerate. Overall, the results suggest that at environmental concentrations of 0.1 μg/L, mayflies and stoneflies would be eliminated and riffle beetles, caddisflies, and some chironomids would be present in significantly reduced numbers.
Integrated laboratory and field approach for assessing impacts of heavy metals at the Arkansas River, Colorado
Authors: Clements William H. , Kiffney Peter M. 
Published: March 2010

AbstractThis research employed an integrated laboratory and field approach to assess effects of heavy metals at the Arkansas River, a Colorado stream impacted by historic mining operations. Ambient metal levels, chronic toxicity, metal bioaccu-mulation by benthic organisms, and benthic community structure were examined at stations located upstream and downstream from California Gulch (CG), a U.S. Environmental Protection Agency Superfund site near Leadville, Colorado. Although each approach demonstrated effects of metals from CG, important differences among approaches were observed. Ambient metal concentrations and chronic toxicity tests conducted with Ceriodaphma dubia indicated reduced water quality at upstream and downstream stations. Because of temporal variability in metal levels, water samples collected for chronic toxicity tests did not reflect average exposure conditions. Instream monitoring of benthic communities was necessary to characterize metal impacts at the Arkansas River, but this approach had limitations. Levels of metals in periphyton and benthic invertebrates were significantly elevated at stations downstream from CG. Variation in metal levels among taxa and the absence of some taxa from some stations may limit the use of bioaccumulation studies for monitoring metal impacts. Benthic community structure was altered downstream from CG, but some metrics (e.g., species richness, abundance) were not affected by heavy metals because of the replacement of sensitive taxa by tolerant taxa. Because each of the approaches employed in this study provided different information on the degree of metal impacts, we recommend an integrated approach for assessing effects of metals on streams.