bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation in DNA content of blood cells of largemouth bass from contaminated and uncontaminated waters
Authors: Lingenfelser Susan F , Dallas Cham E , Jagoe Charles H , Smith Michael H , Brisbin I Lehr , Chesser Ronald K 
Published: March 2010

Abstract
Largemouth bass (Micropterus salmoides) were collected from locations with and without documented histories of pollution in Georgia and South Carolina. Whole blood samples were collected from over 3,000 bass and analyzed by flow cytometry to measure changes in cellular DNA content and cell cycle distribution. The coefficient of variation (CV) of the cell cycle phase G0/G1 peak was used as a measure of variation in DNA content within an individual. The mean CV varied significantly among locations, and some locations with known chemical or radioactive contaminants had higher CVs. Plotting the frequency distribution of CV values for each site revealed greater skewness and kurtosis in most locations with known contaminants. In each case, a right skewness indicated higher proportions of bass with unusually high CV in these locations. Aneuploid-like patterns were detected in the DNA histograms of five fish, all from locations with histories of contamination. The percentage of cells distributed among phases of the cell cycle (G0/G1, S, and G2/M) varied significantly among locations, but there was no apparent relationship to contaminant distribution. Differences in CV and frequency of aneuploids among sites with and without histories of pollution were generally small, but increased variation in DNA content may be associated with contaminant exposure at some locations.
Source and identity of compounds in a thermomechanical pulp mill effluent inducing hepatic mixed-function oxygenase activity in fish
Authors: Martel Pierre H , Kovacs Tibor G , O'Connor Brian I , Voss Ron H 
Published: March 2010

Abstract
The source and identity of two mixed-function oxygenase (MFO)-inducing substances present in the primary-treated effluent of a thermomechanical pulp (TMP) mill producing newsprint was determined. The source was pinpointed by exposing rainbow trout (Oncorhynchus mykiss) to various process effluents sampled throughout the mill. Exposure concentrations were based on the flow of these process streams in relation to the final effluent flow. Contaminated TMP steam condensates were identified as the major process source of MFO-inducing substances. Using conventional extraction and fractionation procedures, an MFO-inducing fraction was isolated. The major gas chromatographic peaks in this fraction were identified by gas chromatography/mass spectrometry as juvabione, dehydrojuvabione, and manool, all naturally occurring extractives in balsam fix (Abies balsamea). These substances were extracted and isolated from balsam fir and TMP condensates. Trout exposed to juvabione and dehydrojuvabione responded by exhibiting significant hepatic MFO inductions. No MFO induction was observed for manool. Secondary treatment in an activated sludge system effectively eliminated the MFO-inducing potential of the combined mill effluent consistent with a corresponding 90% reduction of both juvabione and dehydrojuvabione.
Effects of chlorpyrifos on individuals and populations ofDaphnia pulexin the laboratory and field
Authors: van der Hoeven Nelly , Gerritsen Anton A M 
Published: March 2010

AbstractEffects of the insecticide chlorpyrifos (cpf) on young (&lt;1 d old) and adult (7–9 d old) Daphnia pulex and the ability of D. pulex to recover after exposure were tested in the laboratory. Populations of D. pulex exposed to cpf were studied in the laboratory and field. In the field, cpf was applied in a single dose. The effects of that dose on D. pulex populations were tested and compared with the effects of a simulated single dose and its ensuing decay on populations in the laboratory. The lowest no-observed-effect concentration was about 0.05 μg/L (actual concentration). Chlorpyrifos immobilized D. pulex several days before death. Juveniles became immobilized faster than adults. Even when no longer exposed, D. pulex immobilized by cpf died. In the laboratory and field, observed population dynamics and effects of cpf on these dynamics were very similar. The median effective concentration for population size after 2 and 7 d of exposure did not differ between the laboratory and field (2 d, 0.38 and 0.31 μg/L, respectively; 7 d, 0.25 and 0.34 μg/L, respectively). Effects of cpf on single-species Daphnia populations in the laboratory and field can be predicted from effects observed in tests with individuals.
Equilibrium partitioning of heavy metals in dutch field soils. II. Prediction of metal accumulation in earthworms
Authors: Janssen René P T , Posthuma Leo , Baerselman Rob , Den Hollander Henri A , Van Veen Rens P M , Peijnenburg Willie J G M 
Published: March 2010

Abstract
To evaluate the adequacy of the equilibrium partitioning concept in predicting metal bioaccumulation, a soil invertebrate species was exposed in 20 Dutch field soils with moderate metal contamination. Earthworms (Eisenia andrei) were kept in the soils for 3 weeks under laboratory conditions. Bioconcentration factors (BCFs) for six metals (Zn, Cu, Pb, Cd, Cr, Ni) and for As were calculated as the ratio of body- and solid-phase metal concentrations. Multivariate statistical analyses suggested that the BCFs for As, Cd, Cu, and Zn are governed by the same soil characteristics that determine equilibrium partition coefficients between the soil solid phase and the pore water. This suggests that uptake of metals is either direct from the pore water or indirect through an uptake route closely related to pore water. Regression equations were derived for predicting BCF values as a function of easily determinable soil characteristics. By means of internal validation it was shown that the equations obtained can be used for predictive purposes within the range of soil properties encountered in the dataset. Due to a lack of data, external validation was possible only in a qualitative sense.
Accelerated increase in mercury contamination in north Atlantic mesopelagic food chains as indicated by time series of seabird feathers
Authors: Monteiro Luís R , Furness Robert W 
Published: March 2010

Abstract
Concentrations of mercury in the environment have increased manyfold since preindustrial times as a result of anthropogenic emissions of gaseous mercury to the atmosphere. However, most records of historical change are affected by regional inputs and evidence of global impact of human activities at pristine oceanic sites is scanty. Seabird feathers contain a valuable record showing historical trends in methylmercury contamination. Some seabirds are top predators in epipelagic and others in mesopelagic food chains and thus reflect methylmercury contamination of these ecosystems. Here, we report the first measurements of mercury concentrations in a time series of animals from the subtropical northeast Atlantic over the last 100 years. These data show increases in mercury levels by 1.1 to 1.9%/year in epipelagic foodchains and by 3.5 to 4.8%/year in mesopelagic food chains. While the rate of increase in the epipelagic ecosystem is in close agreement with model predictions, the higher rate in the mesopelagic ecosystem has not previously been detected. However, the latter concurs with methylmercury production below the thermocline and conveys new insights into the understanding of the anthropogenic impact in the marine cycle of mercury.
Dietary uptake in pike (Esox lucius) of some polychlorinated biphenyls, polychlorinated naphthalenes and polybrominated diphenyl ethers administered in natural diet
Authors: Burreau Sven , Axelman Johan , Broman Dag , Jakobsson Eva 
Published: March 2010

AbstractThe dietary uptake of 12 halogenated diaromatic compounds was studied using northern pike (Esox lucius L.) fed with rainbow trout (Oncorhynchus mykiss (Walbaum)). Before the trout were fed to the pike, they had been injected with a cocktail of five polychlorinated biphenyls, four polychlorinated naphthalenes, and three polybrominated diphenyl ethers, dissolved in rainbow trout lipid. The reported uptake efficiencies (E) were in the range 35 to 90% and differ in some respect from earlier studies. The E-values for those substances with effective cross sections (ECS) &gt;9.5 Å were considerably higher than expected if the membrane permeation at dietary uptake was restricted as proposed previously in the literature. There was no hydrophobicity dependency of the total dietary uptake efficiency as suggested by an earlier proposed empirical model. The difference between the results presented here and earlier studies is likely to depend on cotransport with lipids and/or proteins through a mediated, possibly active uptake of hydrophobic organic compounds (HOC) in the gastrointestinal tract enabled by the actual exposure method. For the proposed mediated/active uptake of HOCs, the uptake efficiency varied with molecular weight and was greatest for a molecular weight of approximately 450.
Xenobiotic and steroid biotransformation enzymes in Atlantic salmon (Salmo salar) liver treated with an estrogenic compound, 4-nonylphenol
Authors: Arukwe Augustine , Förlin Lars , Goksøyr Anders 
Published: March 2010

Abstract
Hepatic microsomal biotransformation reactions with xenobiotic and steroid substrates have been investigated in 4-non-ylphenol (NP; 1, 5, 25, and 125 mg/kg body weight)-treated juvenile Atlantic salmon (Salmo salar), in addition to control and estradiol-17β (5 mg/kg, positive control)-treated fish. Treatment of juvenile salmon with NP caused an initial increase and an apparent dose-dependent decrease in progesterone 6β-, 16α, and 17α-hydroxylase activities in liver microsomes. 7-Ethoxyresorufin O-deethylase and UDP-glucuronosyltransferase activities were also reduced. Plasma levels of estradiol-17β (E2) were lowered 24–43% as a result of NP treatment. Immunochemical analysis of CYP1A, CYP2K-like, and CYP3A-like proteins showed 18%, 47%, and 30% reductions in enzyme-linked immunosorbent assay absorbance levels, respectively, in the groups treated with 125 mg NP/kg fish. The group treated with E2 also showed similar reductions. In summary, the present study has demonstrated variations in steroid hydroxylases, cytochrome P450 isozymes, and conjugating enzyme levels in NP-treated juvenile salmon. These results represent a novel aspect of NP effects not previously demonstrated with an environmental estrogen in any fish species or lower vertebrate.
Ecological risk assessment of pesticides on muskrats (Ondatra zibethicus) Inhabiting an agriculture area in Illinois, USA
Authors: Juhlin Steven E , Halbrook Richard S 
Published: March 2010

Abstract
A retrospective risk assessment was used to investigate whether pesticide use adversely affected populations of muskrats (Ondatra zibethicus), semi-aquatic mammals inhabiting agriculture drainage ditches in northwestern Illinois. Assessment endpoint benchmark concentrations in water were calculated for muskrats from laboratory rat multiple-generation reproduction no-observed-effect levels. The pesticide root zone model and exposure analysis modeling system simulated pesticide fate and revealed expected environmental concentrations (EECs) of pesticide in receiving water. The EECs following agriculture practices and meteorologic events typical of northern Illinois were below endpoint benchmark concentrations. A modeled worst-case scenario of exposure (three times the typical application rates and 1 cm of rain on the day of application) also revealed EECs below endpoint benchmarks. Assessment results suggested that muskrat populations in northern Illinois were not at risk from the application of pesticides. Results from two other lines of evidence further supported conclusions of this risk assessment.
Effects of mercury and selenium on glutathione metabolism and oxidative stress in mallard ducks
Authors: Hoffman David J , Heinz Gary H 
Published: March 2010

Abstract
Earlier studies have reported on the toxicity and related oxidative stress of different forms of Se, including seleno- D,L-methionine, in mallards (Anas platyrhynchos). This study compares the effects of Se (seleno-D,L-methionine) and Hg (methylmercury chloride) separately and in combination. Mallard drakes received one of the following diets: untreated feed (controls), or feed containing 10 ppm Se, 10 ppm Hg, or 10 ppm Se in combination with 10 ppm Hg. After 10 weeks, blood, liver, and brain samples were collected for biochemical assays. The following clinical and biochemical alterations occurred in response to Hg exposure: hematocrit and hemoglobin concentrations decreased; activities of the enzymes glutathione (GSH) peroxidase (plasma and liver), glutathione-S-transferase (liver), and glucose-6-phosphate dehydrogenase (G-6-PDH) (liver and brain) decreased; hepatic oxidized glutathione (GSSG) concentration increased relative to reduced glutathione (GSH); and lipid peroxidation in the brain was detected by increased thiobarbituric reactive substances (TBARS). Effects of Se alone included increased hepatic GSSG reductase activity and brain TBARS concentration. Selenium in combination with Hg partially or totally alleviated effects of Hg on GSH peroxidase, G-6-PDH, and GSSG. These findings are compared in relation to field observations for diving ducks and other aquatic birds. It is concluded that since both Hg and excess Se can affect thiol status, measurement of associated enzymes in conjunction with thiol status may be a useful bioindicator to discriminate between Hg and Se effects. The ability of Se to restore the activities of G-6-PDH, GSH peroxidase, and glutathione status involved in antioxidative defense mechanisms may be crucial to biological protection from the toxic effects of methylmercury.
An epizootic of common loons in coastal waters of North Carolina: Concentrations of elemental contaminants and results of necropsies
Authors: Augspurger Tom , Franson J C , Converse Kathryn A , Spitzer Paul R , Miller Erica A 
Published: March 2010

Abstract
A 1993 die-off of common loons (Gavia immer) in the coastal waters of North Carolina was investigated with emphasis on comparing mercury, selenium, arsenic, and lead between birds from the epizootic and reference specimens. Die-off specimens were emaciated but contained no ingested foreign bodies and no lesions suggestive of infectious disease. Results of bacteriology, virology, parasitology, and botulism testing were unremarkable. The geometric mean concentrations (wet weight) of liver mercury (10.9 ppm), and arsenic (0.96 ppm) did not differ between specimens from the die-off and reference loons from the same area that died of other causes. The geometric mean liver selenium concentration of die-off specimens (10.4 ppm) was significantly higher than that of reference loons. Liver lead concentrations were &lt; 0.20 ppm in all but one sample (5.83 ppm). The geometric mean mercury concentration in the primary remiges of die-off specimens (5.44 ppm dry weight) was significantly lower than in reference birds. Liver mercury significantly correlated with liver selenium on a molar concentration basis. We interpret the range of liver mercury concentrations in birds from the epizootic, similar liver mercury concentrations in reference loons, and higher mercury concentrations in reference loon feathers as evidence that factors other than mercury were primarily responsible for the emaciation diagnosed as the cause of mortality.
Genotoxic substances in the St. Lawrence system I: Industrial genotoxins sorbed to particulate matter in the St. Lawrence, St. Maurice, and Saguenay rivers, Canada
Authors: White Paul A , Rasmussen Joseph B , Blaise Christian 
Published: March 2010

Abstract
Previous investigations of organic genotoxins in industrial effluents discharged into the St. Lawrence Rivers system (Quebec, Canada) indicated that a substantial fraction of the genotoxicity is adsorbed to suspended particulate matter. This study used the SOS Chromotest to investigate the presence, potency, and behavior of particle-bound genotoxins in the downstream ecosystem. The results indicate that although extracts of both suspended and sedimented particulate matter are genotoxic, suspended particulate matter samples are more potent in the absence of S9 activation, with the reverse being true for bottom sediments. The results confirmed a positive relationship between the genotoxicity of bottom sediment extracts and sediment organic matter content. A similar relationship between organic matter content and total polycyclic aromatic hydrocarbon (PAH) concentration indicates that putative genotoxins have physicochemical properties similar to the PAH class of contaminants. Conversion of PAH values to benzo[a]pyrene equivalents indicates that measured PAHs only account for a small fraction (∼10%) of the observed SOS Chromotest response. Sites that receive discharges from foundries, aluminum refineries, and petroleum refineries yielded several of the most genotoxic samples. Further analyses revealed that the genotoxicity of suspended and sedimented particulate matter extracts is empirically related to the genotoxicity of industrial discharges. Comparisons of total genotoxicity levels in suspended particulates and bottom sediments suggest that direct-acting substances adsorbed to suspended matter are rapidly degraded and/or converted to more stable progenotoxins upon deposition. Further research is required to test this hypothesis and investigate effects on indigenous biota.
A model of the fate of polycyclic aromatic hydrocarbons in the Saguenay Fjord, Canada
Authors: Lun Rebecca , Lee Kenneth , De Marco Lisa , Nalewajko Czesia , Mackay Donald 
Published: March 2010

AbstractA comprehensive mass balance model is described that simulates the fate of polycyclic aromatic hydrocarbons (PAHs) in the Saguenay Fjord in eastern Quebec, Canada. The receiving environment is segmented into five compartments that are connected by upstream and downstream flows. Each segment consists of a layer of surficial sediment and a water column exposed to the atmosphere. The steady state model provides a method by which defined loadings of PAHs from the atmosphere and industrial sources are combined with other input parameters such as advective flow and atmospheric deposition rates to deduce quantities, concentrations, and transport and transformation rates. Results are presented for naphthalene, phenanthrene, and benzo[a]pyrene. The overall environmental pathways and simulation results are discussed. The simulated concentrations of benzo[a]pyrene in the sediment ranged from 100 to 315 ng/g, which are in good agreement with reported measurements.
Sediment toxicity and benthic communities in mildly contaminated mudflats
Authors: Nipper Marion G , Roper David S , Williams Erica K , Martin Michael L , Van Dam Laurence F , Mills Geoffrey N 
Published: March 2010

Abstract
Sediment physicochemical characteristics, benthic community structure, and toxicity were measured at reference and contaminated intertidal mudflats around the North Island of New Zealand. Chronic whole-sediment toxicity tests were conducted with the estuarine amphipod Chaetocorophium lucasi and the marine bivalve Macomona liliana, and pore-water toxicity tests were conducted with embryos of the echinoid Fellaster zelandiae. Although concentrations of organic chemicals and heavy metals were up to several orders of magnitude higher at the sites considered to be contaminated, levels of contamination were relatively low compared to internationally based sediment quality guidelines. Although no pronounced difference was found in benthic community structure between reference and contaminated sites, multivariate analysis indicated that natural sediment characteristics (total organic carbon, acid-volatile sulfide, ammonium) and factors related to contamination (dichlorodiphenyltrichloroethane, sediment toxicity) may have been affecting community structure. Although benthic effects caused by present levels of contamination are not yet dramatic, subtle changes in community structure related to pollution may be occurring. The two whole-sediment and the pore-water toxicity tests presented different response patterns. Growth of C. lucasi and M. liliana was a less sensitive endpoint than survival. None of the three toxicity tests responded more strongly to the contaminated than to the reference sites, that is, neither natural-sediment and pore-water characteristics nor unmeasured contaminants affected the test organisms. It is possible that sediment collection and handling may have induced chemical changes, confounding interpretation of toxicity tests.
Aerobic biodegradation of a silver-bearing photoprocessing wastewater
Authors: Pavlostathis Spyros G , Maeng Sung Kyu 
Published: March 2010

Abstract
Aerobic biodegradation of a photoprocessing wastewater (with a silver level attained after silver recovery) was assessed using fill-and-draw activated sludge reactors. The extractability of silver from the resulting waste activated sludge was also determined. Simulated, fixer-derived wastewater was fed to the activated sludge reactors at a volumetric loading level of 40% along with an organic mixture. The biodegradation of the organic mixture was not affected by the photoprocessing wastewater. Thiosulfate was completely oxidized to sulfate. Complete conversion of ammonia to nitrite was observed, but much lower levels of nitrate were detected in the fixer and fixer-plus-silver-amended reactors, as compared to the control reactor (fed only the organic mixture). Silver at an influent total silver concentration of 1.85 mg/L did not result in any adverse effects on the activated sludge process. Filtered (through a 0.2-μm membrane filter) effluent silver concentrations were below the detection limit of 0.01 mg/L. Practically, all silver was associated with the sludge solids and the mean steady-state silver content of the sludge was 1.84 mg Ag/g mixed liquor suspended solids. When fresh sludge and aerobically digested sludge solids were subjected to the toxicity characteristic leaching procedure, the resulting silver concentration was at least 40 times lower than the regulatory limit of 5 mg Ag/L.
Reactivity of Ag+ ion with thiol ligands in the presence of iron sulfide
Authors: Adams Nicholas W.H , Kramer James R 
Published: March 2010

Abstract
Dissolved silver (Ag) in the presence of amorphous iron sulfide(FeS) rapidly equilibrates to ultra-trace levels ( ∼5 ng/L), which agrees with equilibrium calculations based on Ag2S solubility. This finding, along with the authors' discovery that crystalline Ag2S (acanthite) precipitates rapidly under supersaturated conditions, suggests that a discrete Ag-S phase is formed. Furthermore, potential interferences (Cl−, Cu2+, and dissolved organic carbon) show no effect on the Ag-FeS system. Only the presence of organosulfur (thiol) ligands at 10−3 to 10−4 M result in increased dissolved silver. Agreement between calculations and measured values were good for 1.8 × 10−4 M 3-mercaptopropanoic acid; however, calculations predicted higher dissolved silver than measured values for higher thiol levels, possibly due to Ag-thiol binding to FeS.
Copper tolerance in iron-reducing bacteria: Implications for copper mobilization in sediments
Authors: Markwiese James T , Meyer Joseph S , Colberg Patricia J.S 
Published: March 2010

Abstract
Iron-reducing bacteria enriched from a Cu-contaminated sediment were more tolerant of Cu adsorbed to hydrous ferric oxide (HFO) than were pristine-sediment bacteria. Tolerance was enhanced by increasing the Cu concentration in the culture medium over time, enabling the bacteria to begin reducing Cu-contaminated HFO sooner and at a faster rate than Cu-intolerant bacteria. Copper tolerance confers a greater ability to reduce contaminated HFO and may result in a greater potential for Cu mobilization in sediments.