bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organochlorine compounds in pine needles: Methods and trends
Authors: Strachan William M. J. , Kylin Henrik , Eriksson Göran , Jensen Soren 
Published: March 2010

Abstract
During April 1989, needles from Scotch pine (Pinus sylvestris) trees were collected from a network of stations in West Germany, Denmark, Norway, and Sweden. Samples from selected stations were analyzed for hexachlorobenzene (HCB), pen-tachlorophenol (PCP), hexachlorocyclohexane isomers (α-HCH and γ-HCH [lindane]), DDT, and DDE. Accumulation of the investigated compounds was observed in up to four needle-year classes. γ-HCH decreased from south to north; the pattern for α-HCH was uniform; DDT/DDE also decreased from south to north. HCB was uniform throughout the sample area, and PCP was high in northern Sweden. Interpretation of trends was not altered by expressing concentrations on a fresh- or dry-weight basis or on a surface-area basis. The range of concentration variation for equivalent samples was 2 to 49% relative standard deviation; averages were 20 to 23%. There were no differences among trees facing the same open direction; among different directions, trees open to the south collected more DDT, but this was not the case with other substances. There were no differences between trees of different ages. Samples at 4 to 5 m had lower contaminant levels than from 1.5 m.
Evaluation of peroxidase as a biochemical indicator of toxic chemical exposure in the aquatic plant Hydrilla Verticillata, Royle
Authors: Byl Tom D. , Sutton Heather D. , Klaine Stephen J. 
Published: March 2010

Abstract
Laboratory bioassays were conducted to determine the utility of peroxidase (POD) activity as a biochemical indicator of contaminant exposure in the aquatic plant Hydrilla verticillata, Royle. The plants were exposed to anthracene, sulfomet-uron methyl (Oust®), Cd2+, Cr6+, Cu2+, Mn2+, and Se4+ in concentration factors of 10. POD was extracted and measured by spectrophotometric assay. There was a significant increase in POD activity after a 5-d exposure to each of the chemicals at 1 mg/L. The optimum pH for POD activity after exposure to the chemicals was 5.5 to 6.0. The increase in POD was found to be dose dependent for each of the chemicals. The lowest concentration of chemical to induce a significant POD increase was 0.01 mg/L for anthracene, Oust, Cd, Cr, and Cu; 0.1 mg/L for Se; and 1.0 mg/L for Mn.
Toxicity of 2,3,7,8-tetrachlorodibenzo-P-dioxin to brook trout (lsalvelinus fontinalis) during early development
Authors: Walker Mary K. , Peterson Richard E. 
Published: March 2010

Abstract
The sensitivity of early life stages of brook trout (Salvelinus fontinalis) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity was investigated. Newly fertilized eggs were exposed for 48 h to water containing either acetone or a range of concentrations of [3H]TCDD dissolved in acetone. Eggs were then transferred to TCDD-free water and observed through development. TCDD concentrations of 101 to 470 pg/g in the eggs caused dose-related increases in sac-fry mortality associated with yolk-sac edema, hemorrhages, and arrested development. These signs of TCDD-induced toxicity resemble blue-sac disease. The NOELs and LOELs for sac-fry mortality were 135 and 185 pg TCDD/g egg, respectively, whereas the LD50 and LD100 (95% fiducial limits) were 200 (179-215) and 324 (283-488) pg/g egg, respectively. The time course and signs of TCDD toxicity to brook trout during early development are essentially identical to those observed in both rainbow trout and lake trout following TCDD exposure of their eggs via water or injection, and in lake trout exposed to maternally derived TCDD. Brook trout sac fry are intermediate in sensitivity to TCDD-induced lethality compared to lake trout and rainbow trout.
Evaluation of heavy-metal ion toxicity in fish cells using a combined stress protein and cytotoxicity assay
Authors: Ryan John A. , Hightower Lawrence E. 
Published: March 2010

AbstractAll organisms, from bacteria and yeast to humans, respond to physical and chemical stressors by increasing the synthesis of a small group of ‘cellular stress proteins.’ We have developed a simple in vitro system for quickly screening environmentally relevant stressors to detect stress-induced proteins that are good candidates for biomarkers. Polyacrylamide gel electrophoresis was used to detect stressor-induced, concentration-dependent changes in cellular stress protein levels in two fish cell culture systems, whereas simultaneous in vitro neutral red uptake cytotoxicity assays measured the stressor's effect on cellular physiology. There was a direct concentration-dependent relationship between sublethal cytotoxic effects and the increases in stress protein levels. Increases of 50 to 200% were detected in stress proteins from desert topminnow, Poeciliopsis lucida, hepatoma-derived cell cultures exposed to cadmium (six proteins) or copper (four proteins). Three proteins showed similar increases in winter flounder, Pleuronectes americanus, kidney cell cultures exposed to the same stressors. Increases in the evolutionarily conserved heat-shock protein hsp70 were detected in each experiment; its level increased with increasing stressor concentrations.
Influence of species and sex on metal residues in freshwater mussels (family unionidae) from the St. Lawrence river, with implications for biomonitoring programs
Authors: Metcalfe-Smith Janice L. 
Published: March 2010

Abstract
The implementation of freshwater mussel watch programs has been hindered by a lack of information on biological factors affecting the levels of contaminants accumulated by these organisms. This study investigated the influence of species and sex on metal residues in Elliptio complanata and Lampsilis radiata radiata (Family Unionidae) from the St. Lawrence River. Mussels were collected from sites representing a wide range of types and degrees of metal pollution. Composite samples of five specimens (males and females combined) per species per site and five specimens per sex per species per site were analyzed for residues of 12 metals in the soft tissues to determine the effects of species and sex, respectively, on variability in the data. Interspecific differences in bioaccumulation were observed for most metals; however, concentrations were frequently correlated between species and the differences could therefore be quantified. Elliptio complanata demonstrated a broader response range to the same exposures than Lampsilis radiata radiata for most metals, suggesting that it may be more sensitive to changes in pollution status. Differences in metal uptake between the sexes were less pronounced than differences between species, and male specimens displayed less variability than females. Consideration of these factors in mussel biomonitoring programs should greatly improve sensitivity and precision.
Effects of different food doses on cadmium toxicity to Daphnia magna
Authors: Kluttgen Birgit , Ratte Hans Toni 
Published: March 2010

Abstract
Chronic toxicity tests were conducted with Daphnia magna using cadmium concentrations of 0, 0 5, 1, 2, and 5 μg/L Cd with algae doses of 0 8, 4, 8, and 16 106 cells/d of Chlorella saccharophila for each In this way we were able to determine the effects of cadmium on the life table data of individuals, under different nutritional conditions The development of juvemles was found to be inhibited by cadmium at low food doses, whereas body length and reproduction were strongly affected at higher food levels The molting interval of adults and the development rate of embryos proved to be unaffected by cadmium Cadmium stressed animals lived longer than did the unstressed controls The intrinsic rate of natural increase was generally reduced by cadmium, independent of the food dose
Relation among cytochrome p450, ah-active pcb congeners and dioxin equivalents in pipping black-crowned night-heron embryos
Authors: Rattner Barnett A. , Hatfield Jeff S. , Melancon Mark J. , Custer Thomas W. , Tillitt Donald E. 
Published: March 2010

AbstractPipping black-crowned night-heron (Nycticorax nycticorax) embryos were collected from a relatively uncontaminated site (next to Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). Hepatic cytochrome P450-associated monooxygenases and cytochrome P450 proteins, induced up to 85-fold relative to the reference site, were associated with concentrations of total polychlonrinated biphenyls (PCBs) and 11 PCB congeners that are presumed to express toxicity through the arylhydrocarbon (Ah) receptor Multiple regression revealed that up to 86% of the variation of cytochrome P450 measurements was accounted for by variation in the concentration of these PCB congeners. Toxic equivalents (TEQs) of sample extracts, predicted mathematically (summed product of PCB congener concentrations and toxic equivalency factors), and dioxin equivalents (TCDD-EQs), derived by bioassay (ethoxyresorufin-O-dealkylase activity of treated H4IIE rat hepatoma cells), were greatest in Cat Island samples. Cytochrome P450-associated monooxygenases and cytochrome P450 proteins were related to TEQs and TCDD-EQs; adjusted r2 often exceeded 0 5 for the relation among mathematically predicted TEQs and cytochrome P450 measurements. These data extend previous observations in heron embryos of an association between P450 and total PCB burdens to include Ah-active PCB congeners, and presumably other compounds, which interact similarly with the Ah receptor Benzyloxyresorufin O-dealkylase, ethoxyresorufin O-dealkylase, and cytochrome P450 1A appear to be the most reliable measures of exposure to Ah-active PCB congeners in black-crowned night-heron embryos. These findings provide further evidence that cytochrome P450-associated parameters have considerable value as a biomarker for assessing environmental contamination of wetlands
Low ph effects on swimming activity of Ambystoma salamander larvae
Authors: Kutka Franz J. 
Published: March 2010

Abstract
Swimming activity of larval Ambystoma laterale increased linearly with pH between pH 4.0 and 6.5; near inactivity occurred at pH 4.0. Ambystoma maculatum exhibited a weaker relationship between activity and pH, and overall was less active than A. laterale. However, survival of larval A. maculatum declined linearly with pH in the presence of adult diving beetles (Dytiscus verticalis), with significantly lower survival below pH 4.8. These results suggest that, as with embryos, salamander larvae may suffer from pH levels below 5.0, even though these levels are not directly lethal. Because of their sensitivity, ease, and short duration, activity tests are recommended with amphibian larvae for use in other risk assessments.
The role of grazers and shredders in the retention and downstream transport of a pcb in lotic environments
Authors: Sallenave Rossana M. , Day Kristin E. , Kreutzweiser David P. 
Published: March 2010

AbstractField studies using flow-through artificial stream channels were conducted between May and October 1992 to study the role of the feeding activity of grazing and shredding invertebrates in promoting downstream transport of 2,2′,4,4′,5,5′-hexachlorobiphenyl (HCBP). Plant material was labeled with [14C]HCBP and fed to selected invertebrate species, and accrual of radioactivity by downstream collector species (Hydropsyche spp.) was measured. Downstream transport of HCBP was significantly increased by the presence of the grazer Elimia livescens in the upstream sections of the channels as demonstrated by significantly higher levels of radioactivity in hydropsychid larvae located downstream. Similarly, movement of HCBP downstream was significantly greater in channels containing the shredder Hydatophylax argus than in channels without shredders. These results suggest that the feeding processes of benthic invertebrates may play an important role in the downstream transport of particle-bound hydrophobic organic compounds.
A comparison of algorithms for global characterization of confidence regions for nonlinear models
Authors: Klepper Olivier , Hendrix Eligius M. T. 
Published: March 2010

Abstract
Environmental models are often highly nonlinear, and parameters have to be estimated from noisy data. The standard approach of locally linearizing the model, which leads to ellipsoid confidence regions, is inappropriate in this situation. A straightforward technique to characterize arbitrary-shaped confidence regions is to calculate model output on a grid of parameter values. Each parameter value P results in a goodness of fit G(P), which allows delineation of the set of parameters corresponding to G(P) &lt; Gc, with Gc some threshold level (e.g., 5% probability). This approach is impractical and time-consuming for complex models, however. This article aims at finding an efficient alternative. It is first shown that the most general approach is to generate parameter values uniformly covering the set G(P) &lt; Gc rather than finding the boundary G(P) = Gc. It is argued that the most efficient method of generating a uniform cover is by a (theoretical) algorithm known as pure adaptive search (PAS); the presently proposed method (uniform covering by probabilistic rejection; UCPR) is shown to be a good approximation to PAS. The UCPR is compared with alternative methods for a number of test problems. It is illustrated that for complex models (where model run time dominates total computer time) UCPR is considerably faster and its cover of Gc more uniform than existing alternatives. An intrinsic problem common to all methods is that the amount of work increases at least quadratically with the number of parameters considered, making them of limited use for high-dimensional problems.
Laboratory measurements of the aqueous solubility of mixtures of chlorinated solvents
Authors: Broholm Kim , Feenstra Stan 
Published: March 2010

Abstract
This article describes the results of laboratory batch solubility experiments with five chlorinated solvents (chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene) present alone or in binary or ternary mixtures. The measured aqueous solubility values of the pure compounds revealed significant deviation from the widely used literature values for trichloroethylene and tetrachloroethylene. The experiments with binary and ternary solvent mixtures showed that the chlorinated solvents used in this study exhibited close to ideal behaviour. That means the concentration of an organic compound in the aqueous phase in equilibrium with an organic phase can be described as the mole fraction in the organic phase times the aqueous solubility of the pure compound. The UNIFAC (universal quasi chemical functional group activity coefficients) method was used in this study to estimate the appropriate activity coefficients for the experiments with binary mixtures. The UNIFAC method predicted nonideal behaviour for some of the mixtures. However, the deviation was only significant at relatively low mole fractions. Experiments indicated that the assumption of ideal behaviour for the chlorinated solvents used in this study is a reasonable one. The assumption of ideal behaviour simplifies the use of models to simulate the dissolution of chlorinated solvent mixtures in ground water.
Effect of alachlor concentration and an organic amendment on soil dehydrogenase activity and pesticide degradation rate
Authors: Felsot Allan S. , Dzantor E. Kudjo 
Published: March 2010

Abstract
Past studies have shown that extremely high concentrations of alachlor in soil can depress microbial biomass and bioactivity; consequently, degradation of alachlor is also inhibited. Studies were undertaken to further characterize the relationship among alachlor concentration in soil, dehydrogenase activity (as an indicator of microbial activity), and degradation rate. Alachlor initially inhibited soil dehydrogenase in soil at concentrations as low as 250 mg/kg with prolonged inhibition through at least 21 d occurring at concentrations ≥750 mg/kg. The inhibition of soil dehydrogenase was associated with a prolonged persistence of alachlor beyond the previously reported ranges of half-life observed at normal field rates of application. Amendment of soil with cornmeal caused degradation of 10 to 250 mg/kg alachlor at rates substantially faster than previously reported for laboratory incubations. At alachlor concentrations ≥750 mg/kg, dehydrogenase activities in amended soils surpassed levels in corresponding no-pesticide controls after 21 d; coincidentally, &gt;50% of the initially added alachlor had degraded during the same period. These results suggested that stimulation of microbial bioactivity by addition of organic amendments may enhance co-metabolism of high concentrations of pesticides in soil.
Phytotoxicity and accumulation of mercury in tobacco subjected to different exposure routes
Authors: Suszcynsky Elaine M. , Shann Jodi R. 
Published: March 2010

Abstract
Experiments were conducted to study the absorption, phytotoxicity, and internal distribution of mercury (Hg) in tobacco plants (Nicotiana miersii) exposed to elemental mercury vapor (Hg0) through the shoot or to ionic mercury (Hg2+) through the root. Tobacco plants grown hydroponically were exposed to varying Hg0 treatment concentrations (0 to 100 mg/m3) in a specially designed chamber system, examined for visible symptoms of toxicity, and analyzed for Hg content by cold vapor atomic absorption, 1 and 10 d following treatment. In a separate experiment, the roots of hydroponic tobacco plants were exposed to Hg2+ in the form of a mercury chloride solution (0 to 100 μg/ml) and analyzed for growth changes and Hg content. Accumulation, toxicity response, and Hg distribution differed between the two exposure routes, even when internal Hg concentrations in the treated plants were similar. Plants exposed to Hg0 accumulated Hg in the shoots with no movement to roots. Visible signs of Hg0 stress were apparent at 1.0 mg/m3 exposure levels and greater. Root-exposed plants showed accumulation of Hg in the roots with movement to the shoots by day 10. Inhibition of root and shoot growth occurred at treatment levels of 1.0 μg/ml and greater with very limited tissue damage at higher treatment levels.
Toxicity of selected pesticides to lake phytoplankton measured using photosynthetic inhibition compared to maximal uptake rates of phosphate and ammonium
Authors: Brown L.S. , Lean D.R.S. 
Published: March 2010

Abstract
The toxicity of 16 pesticides to the energy-producing process of photosynthesis was determined from inhibition or depression of the assimilation rate of [14C]bicarbonate by natural plankton samples collected from Jack's Lake, a mesotrophic lake on the edge of the Canadian Shield 200 km northeast of Toronto, Ontario. Measurements were made at increasing concentrations of pesticide while samples were exposed to optimal light. At the same time, in the same 300-ml bottle, measurements of maximal uptake rates for phosphate and ammonium were made using radiotracer and stable isotope methods. In this way the more commonly used screening technique of photosynthetic inhibition could be compared to the energy-demanding processes of phosphate and ammonium uptake. Phosphate assimilation was inhibited at much higher herbicide concentrations than carbon fixation, whereas ammonium assimilation was inhibited at intermediate concentrations. Herbicides that specifically inhibit photosynthesis were most toxic to carbon uptake, while those herbicides affecting other cellular metabolic processes had a greater influence on phosphate and ammonium assimilation. No relationship was found among pesticide toxicity and molecular weight, solubility, or log Kow.
Heavy metal detoxification by trimercapto-s-triazine (TMT) as evaluated by a bacterial enzyme assay
Authors: Ayoub George M. , Koopman Ben , Bitton Gabriel , Riedesel Kelly 
Published: March 2010

Abstract
We compared trimercapto-s-triazine (TMT) to ethylenediaminetetraacetate (EDTA) for detoxification of five selected heavy metals as part of an effluent fractionation procedure. Toxicity was assessed using a microbial microplate assay, based on the MetPAD™ test kit. The affinity of TMT to four of the metals (Cd, Cu, Hg, Pb) was on the same order of magnitude as EDTA, as indicated by minimum mole ratios of ligand to metal required for detoxification. The TMT was ineffective against Zn. Both TMT and EDTA were toxic (causing more than 30% inhibition) to the test bacterial enzyme at concentrations of 3,000 μM or greater. The range of TMT concentrations that detoxified the metals was broader than that of EDTA. Stimulation of enzyme activity by EDTA could complicate interpretation of test data, a problem not shared by TMT.
Reduction of the efficiency of extraction of lipophilic chemicals from water by dissolved organic matter
Authors: Maguire R James , Batchelor Suzanne P , Sullivan Cheryl A 
Published: March 2010

Abstract
A study was made of the efficiency of liquid-liquid extraction of eight chlorinated hydrocarbons of varying lipophilicity from filtered (1 μm) organic free water, soil humic acid solution, lacustrine dissolved organic matter solution, and a natural water The efficiency of hexane extraction of the spiked chemicals without pH adjustment (i e the conventional technique) was reduced with increasing concentration of dissolved organic matter (DOM) and increasing chemical lipophilicity At the same time, increasing amounts of the more lipophilic chemicals were found in subsequent extracts of the water at pH 12, and after chromic acid oxidation of the DOM The results indicated that conventional liquid-liquid extraction underestimates the concentrations of “dissolved” highly lipophilic chemicals in fresh water, the extent of the underestimation depending upon the nature of the DOM Sixteen day exposure experiments with filtered natural waters containing roughly 5 mg/L DOM indicated that 6 to 8% of the most lipophilic chemical tested, mirex, was not recovered by standard hexane extraction without pH adjustment, with 5 mg/L of a soil derived humic acid, 49% of mirex was not recovered by standard hexane extraction without pH adjustment For highly lipophilic chemicals that are not destroyed by chromic acid oxidation, it is recommended that total concentrations in filtered or centrifuged fresh waters be determined by the chromic acid oxidation/extraction technique
Induction of cytochrome P4501A in the mummichog (Fundulus heteroclitus) by the polychlorinated terphenyl formulation aroclor 5432
Authors: Gallagher Kathryn , van Veld Peter A. , Hale Robert C , Stegeman John J 
Published: March 2010

Abstract
Accumulation of the polychlorinated terphenyl formulation Aroclor 5432 in aquatic species has previously been reported Polychlorinated terphenyls (PCTs) are structurally similar to polychlorinated biphenyls (PCBs), and were used in related applications However, their biological effects have not been thoroughly studied Effects of PCT mixtures on levels of hepatic cytochrome P4501A (P4501A) and associated ethoxyresorufin O-deethylase (EROD) activity in the mummichog (Fundulus heterochtus), a common estuarine fish, were assessed here Fish were injected intraperitoneally with PCT formulations Aroclor 5432, Aroclor 5460, or the PCB formulation Aroclor 1254, at doses of 0 32 to 100 mg/kg body weight Elevated levels of P4501A and EROD activity were detected in fish injected with Aroclor 5432 and Aroclor 1254 doses of 32 and 100 mg/kg Induction resulting from Aroclor 5432 was greater than that caused by equivalent doses of Aroclor 1254 Treatment with Aroclor 5460 did not result in significant induction Because commercial PCT mixtures contain small amounts of PCBs, the PCB components may have contributed to the induction observed for Aroclor 5432 This work represents the first report of hepatic cytochrome P4501A induction caused by Aroclor 5432 in teleosts and, similar to work in mammalian systems, suggests that the effects of this mixture may be at least partially mediated through Ah receptor binding