bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protective effects of calcium against chronic waterborne cadmium exposure to juvenile rainbow trout
Authors: Hollis Lydia , McGeer James C , McDonald D Gordon , Wood Chris M 
Published: March 2010

Abstract
Juvenile rainbow trout (Oncorhynchus mykiss [Walbaum]) on 1% daily ration were exposed to 0 (control) or 2 μg of cadmium as Cd(NO3)2·4H2O per liter added to four different calcium (Ca) concentrations: 260 (background), 470 (low), 770 (medium), or 1200 (high) μM of Ca added as Ca(NO3)2·4H2O in synthetic soft water for 30 d. Mortality was highest (∼80%) in the background + Cd treatment. Approximately 40% mortality was observed in the low + Cd exposure; mortality was 10% or less for all other treatments. No growth effects were seen for any of the exposures. Kidneys accumulated the greatest concentration of Cd during the 30 d, followed by gills and livers. Accumulation of Cd in gills, kidney, and liver decreased at higher water Ca concentrations. No differences in whole-body or plasma Ca concentrations were found. Swimming performance was impaired in the low + Cd-exposed fish. Influx of Ca2+ into whole bodies decreased as water Ca concentrations increased; influx of Ca2+ into background + Cd-treated fish was significantly reduced compared to that in control fish. Experiments that measured uptake of new Cd into gills showed that the affinity of gills for Cd (KCd-gill) and the number of binding sites for Cd decreased as water Ca concentrations increased. Acute accumulation of new Cd into gills and number of gill Cd-binding sites increased with chronic Cd exposure, whereas the affinity of gills for Cd decreased with chronic Cd exposure. Longer-term gill binding (72 h) showed reduced uptake of new Cd at higher water Ca levels and increased uptake with chronic Cd exposure. Complications were found in applying the biotic ligand model to fish that were chronically exposed to Cd because of discrepancies in the maximum number of gill Cd-binding sites among different studies.
Factors affecting risk assessment of small mammals to pesticides
Authors: Edge W Daniel , Schauber Eric M 
Published: March 2010

AbstractThe quotient method (QM), a laboratory-based risk assessment methodology used by the U.S. Environmental Protection Agency to evaluate pesticides for registration and use, has not been thoroughly field-tested and its performance has not always been reliable. Our objective was to compare predictions of risk using the QM with results from small mammal field studies to identify factors that cause variation in the performance of the QM. We regressed estimated mortality of herbivorous gray-tailed voles (Microtus canicaudus) and omnivorous deer mice (Peromyscus maniculatus) against predictions of mortality based on LC50 probit analyses for pesticide concentrations in spray-tank mixtures and residues on the top and bottom 15 cm of alfalfa plants. Predictions of risk generally were correlated with estimated mortality in the field, but slopes often differed significantly from the predicted 1:1 relationship and were much greater than 1.0 for several relationships during the 1993 experiment. Risk predictions may be influenced by a number of factors, including estimation of estimated environmental concentration (EEC), vegetation structure, weather patterns, species of concern, and demographic characteristics of the exposed populations. More accurate risk assessments may be accomplished by improving vegetation nomogram estimates of EEC and by incorporating vegetation structure and differences in natural history among species into QM predictions. Weather following application and the demographic characteristics of the exposed populations are likely to remain unknown and will cause imprecision in risk assessments.
Effects of dietary polychlorinated biphenyl exposure on energetics of white-footed mouse, Peromyscus leucopus
Authors: Voltura Mary Beth , French John B 
Published: March 2010

Abstract
Energy budgets have provided physiological ecologists with a vital link between environmental variables and individual performance and should also prove useful to ecotoxicologists in understanding the effects of sublethal exposure in the field. Exposure to toxic compounds is likely to be metabolically expensive and may result in a trade-off between energy spent to detoxify and excrete contaminants and energy allocated to growth or reproduction. To quantify the energetic cost of polychlorinated biphenyl (PCB) exposure, we fed captive white-footed mice (Peromyscus leucopus) diets containing PCBs (2:1 Aroclor® 1242:1254) at levels of 0, 0.1, 10, and 25 ppm (mg PCBs/kg food). After six weeks on the diets, there were no differences in food intake (g/d), diet digestibility (%), or body mass related to the level of dietary PCBs. This indicated that short-term exposure to PCBs did not cause a detectable increase in energy need as measured by voluntary food intake. We continued to feed mice the PCB-containing diets for one year, at which time we repeated the food intake trial, and also measured oxygen consumption at 20 and 30°C. After one year, all mice had gained mass, but mice on the 25-ppm diet tended to be heavier than mice in the other groups. Compared to the control group, mice on the 25-ppm diet had higher food intake (4.1 vs 3.7 g/d; p = 0.06) and higher oxygen consumption at 30°C (40.1 vs 36.6 ml O2/h; p = 0.01). These results suggest that there is an energetic cost to long-term contaminant exposure that, when combined with other environmental stresses, may influence patterns of energy acquisition and allocation.
Endocrine responses ofFundulus heteroclitusto effluent from a bleached-kraft pulp mill before and after installation of reverse osmosis treatment of a waste stream
Authors: Dubé Monique G , MacLatchy Deborah L 
Published: March 2010

AbstractImplementation of process changes on the nonbleaching side of bleached kraft pulp mill (BKPM) operations has increased in recent years to maximize resource use and to minimize residual environmental effects of discharged effluents. The objective of this study was to determine if reverse osmosis (RO) treatment of evaporator and digester clean condensates reduced or removed the effects of a BKPM effluent on reproductive endocrine function of the estuarine killifish, Fundulus heteroclitus (mummichog). Comparison of data collected before (1997) and after (1998), the years of the process change, showed that the potential of the combined mill effluent to depress plasma testosterone levels after 30 and 57 d of exposure to an environmentally relevant effluent concentration (1%) was reduced after RO treatment of condensates. However, in vitro production of some sex steroids was depressed with a 1% effluent exposure after the process change. In addition, in 1998, depression of plasma testosterone levels in effluent-exposed fish was present at higher effluent concentrations (5%). These results are significant because they suggest that condensates may be a source of endocrine-disrupting compounds in BKPM effluents and RO may reduce their discharge.
Development of an in vivo screening assay for estrogenic chemicals using juvenile rainbow trout (Oncorhynchus mykiss)
Authors: Thorpe Kare I. , Hutchinson Thomas H , Hetheridge Malcolm J , Sumpter John P , Tyler Charles R 
Published: March 2010

Abstract
In this study, the Organisation for EconomicCooperationand Development (OECD) Test Guideline 204 was adapted for the development of an in vivo screen for detecting estrogenic activity using juvenile rainbow trout (Oncorhynchus mykiss). The influence of feeding ration and the effect of reference estrogenic chemicals on somatic growth, gonadosomatic index, hepa-tosomatic index, and plasma vitellogenin concentrations were evaluated over 21 d. A feeding ration of 4% body weight per day resulted in temporal increases in body weight, hepatosomatic index, and plasma vitellogenin concentration in both males and females. A feeding ration of 1% did not induce any changes in the measured endpoints and was adopted for the subsequent estrogen exposures. Exposure of juvenile female fish to 17β-estradiol and 4-tert-nonylphenol produced concentration-dependent inductions of plasma vitellogenin that were optimal after 14 d, with lowest observed effect concentrations of 8.9 ng/L and 16 μg/L, respectively. Methoxychlor also induced synthesis of plasma vitellogenin with a 14-d lowest observed effect concentration of 9.8 μg/L. Higher concentrations of methoxychlor were toxic to fish. Increases in the hepatosomatic index occurred on day 14 in fish exposed to 244 ng/L 17β-estradiol and 53μg/L 4-tert-nonylphenol. None of the compounds tested caused detectable changes in the gonadosomatic index. Vitellogenin induction in juvenile trout was sensitive to estrogenic chemicals, occurred rapidly, and the response was highly consistent between experiments (coefficient of variation = 4.5% for the 17β-estradiol positive control). The 14-d juvenile fish assay offers a sensitive and robust in vivo screening method for estrogen-active substances.
Impact of animal waste lagoon effluents on chlorpyrifos degradation in soils
Authors: Huang Xinjiang , Lee Linda S , Nakatsu Cindy 
Published: March 2010

AbstractAnimal-derived lagoon effluents are a good source of inorganic nutrients and organic matter; however, they may impact the degradation and transport of soil-applied pesticides. The degradation of chlorpyrifos in poultry-, swine-, and cow-derived effluents and effluent-soil matrices were studied using batch and column incubation studies. Chlorpyrifos was degraded by aerobic microbial processes in animal-derived lagoon effluents. Microbial community analysis by denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal ribonucleic acid genes showed that a single band became dominant in effluent during chlorpyrifos degradation. In soils, both biotic and abiotic degradation contributed significantly to the overall dissipation of chlorpyrifos. Large differences in degradation rates were observed between soils, with the fastest rate observed in soil with higher pH and cation-exchange capacity. Effluents appeared to have only a minor effect on chlorpyrifos degradation in soils, although effluent-induced increases in soil-solution pH over time may enhance hydrolysis by a few percent in low-pH soils. Soil properties, not effluent properties, appear to control chlorpyrifos degradation under laboratory conditions; however, the impact on changes in soil properties and microbial ecology with long-term effluent irrigation warrants further investigation.
Mutagenicity of trinitrotoluene and metabolites formed during anaerobic degradation by Clostridium acetobutylicum ATCC 824
Authors: Padda Ranjit S , Wang Chuan Yue , Hughes Joseph B , Bennett George N 
Published: March 2010

Abstract
2, 4, 6-Trinitrotoluene (TNT) and its metabolites formed during anaerobic degradation are mutagenic in Salmonella typhimurium TA98 and TA100 when checked in the absence of rat liver activation system (S9). The monohydroxylamino derivatives that are formed as first-step intermediates of the pathway are less mutagenic than TNT, but the dihydroxylamino derivative that is the second intermediate is much more mutagenic than the parent compound. Whereas TNT is very stable under aerobic as well as anaerobic conditions, the hydroxylamine derivatives are not. The dihydroxylamino derivative of TNT that is the most mutagenic is less stable compared with the monohydroxylamino derivatives of TNT.
Dialysis minipeeper for measuring pore-water metal concentrations in laboratory sediment toxicity and bioavailability tests
Authors: Doig Lorne , Liber Karsten 
Published: March 2010

AbstractWhave modifieda classical peeper (dialysiscell)design to create minipeepers that are ofconvenient sze for direct pore-water sampling in laboratory sediment toxicity and bioavailability tests. A series of experiments placing peepers in nickel and zinc solutions, two size fractions of nickel-spiked sand, and two field-collected, nickel-spiked sediments, were conducted to evaluate peeper efficacy in measuring overlying water and pore-water metal concentrations. In water-only experiments, concentrations in the peeper cells were not significantly different from those in the surrounding solution by 48 and 96 h for nickel and zinc, respectively. Peeper cells in the sand experiments equilibrated with the surrounding pore water in ≤120 h. In both trials with natural sediment, peeper equilibrium occurred in ≤48 h. Nickel flux into the peeper cells during the first hour of experimentation showed that the rate of equilibration was initially related to media porosity. In fine sand and natural sediment, equilibration was influenced not only by nickel diffusion into the peeper cells, but also by a decrease in concentrations of nickel in pore water due to sediment sorption and diffusion into overlying water. This shortened the time required to reach equilibrium by reducing the difference between the peeper cell and the surrounding pore-water solution. Overall, minipeepers equilibrated with the surrounding pore water or overlying water within a time period sufficiently short to allow for the use of minipeepers in routine sediment toxicity and metal bioavailablity experiments. Sampling precision using minipeepers was comparable (CV = 10.8 %) to that obtained by conventional sediment centrifugation and filtration (CV = 10.5 %).
Combined effects between sediment-associated sulfur and lubricant oil on Bacillus cereus
Authors: Tiemann Jan , Ahlf Wolfgang 
Published: March 2010

Abstract
An artificial sediment was spiked with elemental sulfur and a lubricant oil. The measured toxicity in a microbial solid-phase test with Bacillus cereus was markedly enhanced when compared with the effects of the individual toxicants. The joint action was interpreted as augmentation of elemental sulfur toxicity due to facilitation of its solubility by oil components. These results show the demand for consideration of the entire contamination where sediment toxicities are to be assessed.
Mixture toxicity of copper and diazinon to larvae of the mayfly (Ephoron virgo) judging additivity at different effect levels
Authors: van der Geest Harm G , Greve Gerdit D , Boivin Marie-Elen , Kraak Michiel H S , van Gestel Cees A M 
Published: March 2010

Abstract
The toxic unit concept is commonly applied for determining the effects of a mixture of toxicants. Use of this concept is, however, limited to compounds with similarly shaped dose-response relationships. In the present study, a method is proposed to gain insight regarding the influence of differences in the shapes of dose-response relationships on the applicability of the concentration-addition model by judging additivity at different effect levels. To this purpose, two model toxicants with different modes of action and dose-response relationships were selected: copper, and diazinon. Using mortality of the mayfly (Ephoron virgo) as the endpoint, it was demonstrated that the two compounds act in a less-than-concentration-additive manner. Application of the proposed calculation method revealed that the less-than-concentration-addition effect was independent of the effect level on which the mixture was judged.
More male fish embryos near a pulp mill
Authors: Larsson D G Joakim , Ha¨︂llman Hans , Fo¨︂rlin Lars 
Published: March 2010

Abstract
Exposure to endocrine disrupters during early life stages may cause severe long-term effects. One process likely to be affected is sexual differentiation, which in fish can be influenced by both exogenous androgens and estrogens. To investigate if sexual differentiation is disturbed in wild fish exposed to pollutants, we studied embryonic sex ratios in a viviparous, gonochoristic fish species, the eelpout (Zoarces viviparus), whose embryos complete sexual differentiation before birth. The normal sex ratio of the eelpout was close to 50% females at four reference stations. In the effluent gradient of a large Swedish pulp mill, however, the sex ratios were significantly male biased. In light of the endocrine disturbances found near several pulp and paper mills in Europe and North America, it is suggested that endocrine disrupters may interfere with sexual differentiation and, thereby, affect the reproductive potential of fish populations.
Acute and chronic toxicity of nitrate to fathead minnows (Pimephales promelas), ceriodaphnia dubia, andDaphnia magna
Authors: Scott George , Crunkilton Ronald L 
Published: March 2010

AbstractIncreasing concentrations of nitrate in surface water and groundwater are becoming a worldwide concern, yet little information has been published on toxicity of nitrate to common organisms used for toxicity testing. The acute and chronic toxicity of nitrate (NO3-N) to Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas was investigated in 48-h to 17-d laboratory exposures. The 48-h median lethal concentration (LC50) of nitrate to C. dubia and D. magna neonates was 374 mg/L NO3-N and 462 mg/L NO3-N. The no-observed-effect concentration (NOEC) and the lowest-observed-effect concentration (LOEC) for neonate production in C. dubia were 21.3 and 42.6 mg/L NO3-N, respectively. The NOEC and LOEC values for neonate production in D. magna were 358 and 717 mg/L NO3-N, respectively. The 96-h LC50 for larval fathead minnows (P. promelas) was 1, 341 mg/L NO3-N. The NOEC and LOEC for 7-d larval and 11-d embryo-larval growth tests were 358 and 717 mg/L NO3-N, respectively. Additional exposure of breeding P. promelas and their fertilized eggs to nitrate did not increase susceptibility further. The LC50 values for all species tested were above ambient concentrations of nitrate reported for surface water. However, the LOEC for C. dubia was within the range of concentrations that could be found in streams draining areas under extensive agricultural cultivation.
Effects of short-term pulsed ammonia exposure on fish
Authors: Milne Ian , Seager John , Mallett Mike , Sims Ian 
Published: March 2010

AbstractTwo series of laboratory experiments were undertaken to investigate the influences of exposure duration and frequency on the toxicity of short-term pulses of ammonia to rainbow trout (Oncorhynchus mykiss Walbaum) and brown trout (Salmo trutta L.). For the investigation of exposure duration, rainbow trout were exposed to a range of unionized ammonia concentrations in single pulses of 1, 6, or 24 h, and mortality was recorded as the endpoint. For the investigation of exposure frequency, brown trout were exposed to repeated sublethal ammonia pulses of different concentrations either once or three times weekly over a period of 53 d to simulate intermittent pollution episodes. A range of endpoints were measured, including growth, gill condition, blood indices, and organ-to-body weight ratios. The results suggest that exposure duration and frequency are both important factors influencing the severity of effect in fish exposed to short-term ammonia peaks. Growth, gill condition, organ weights, and hematocrit were all significantly affected by repeated exposures, particularly at the higher exposure frequency. The results of this study confirm that the duration and return period of transient pollution events are critical dimensions when considering the development of environmental quality standards for intermittent pollution.
Comparison of polycyclic aromatic hydrocarbon and polychlorinated biphenyl dynamics in benthic invertebrates of Lake Erie, USA
Authors: Gewurtz Sarah B , Lazar Rodica , Douglas Haffner G. 
Published: March 2010

Abstracthedistributionpatternsofpolycyclicaromatichydrocarbons(PAH)andpolychlorinatedbiphenyls(PCBs) were determined in four benthic invertebrate species of western Lake Erie, USA, to assess and compare the processes governing the exposure dynamics of these two classes of contaminants. Significant differences in the sum of 17 PAH compounds were observed among the four species, with mayflies containing the highest PAH body burden, followed by dreissenid mussels, amphipods, and crayfish. For PCBs, mayflies contained significantly higher concentrations of the sum of 39 PCB congeners than the other organisms, and dreissenids had higher levels than crayfish. No significant differences were found in the SPCB levels between dreissenids and amphipods or between amphipods and crayfish. For PCBs, the relationship between biota-sediment accumulation factors (BSAFs) and log Kow followed a parabolic pattern indicative of selective bioaccumulation. In contrast, BSAFs for PAHs were inversely related to log Kow, suggesting that metabolism of the higher Kowcompounds was occurring. These results support the conclusion that mayflies and dreissenids play major roles in the transfer of PAHs and PCBs to upper trophic levels, and they demonstrate that the exposure dynamics of PAHs and PCBs are different in the benthic components of aquatic food webs.
Toxicity, metal uptake, and accumulation of phytochelatins inSilene vulgarisexposed to mixtures of cadmium and arsenate
Authors: Sneller F Else C. , Van Heerwaarden Luisa M , Schat Henk , Verkleij Jos A C 
Published: March 2010

AbstractThe mixture effects of arsenate and cadmium were studied in Silene vulgaris (Moench) Garcke. The results show that the toxicity of the mixtures, measured as inhibition of root elongation, increased with increasing concentrations, ranging from nonadditive or slightly additive to synergistic. The elements did not influence each other's uptake. This was as expected, considering the differences in uptake mechanisms between both elements. Concentrations of detoxifying phytochelatins (PCs) were additive, with respect to both external and root-internal metal concentrations. However, at high exposure concentrations, the plants metabolism collapsed, resulting in very low PC concentrations.
Bioavailability of chlorinated dibenzo-p-dioxins and dibenzofurans to dungeness crab (Cancer magister) at marine pulp mill sites in British Columbia, Canada
Authors: Yunker Mark B , Cretney Walter J 
Published: March 2010

AbstractSynchronous samples of sediment and Dungeness crab (Cancer magister) hepatopancreas, which were obtained for monitoring and assessment purposes at British Columbia, Canada, marine pulp mill sites between 1990 and 1995, were used to calculate biota-sediment accumulation factors (BSAFs) for individual chlorinated dibenzo-p -dioxin and dibenzofuran congeners (PCDD/Fs). The BSAFs for individual pairs of samples were highly variable, and no systematic trends were apparent in the observed accumulation factors over time, with crab size, with crab lipid concentration, with sediment percent organic carbon, or among mill sites or depositional environments. Composition and source differences in sedimentary PCDD/Fs, which are apparent as principal components analysis class separations in the sediment data set, also did not correlate with differences in BSAFs. This independence from environmental factors provides a valuable endorsement of the BASF concept for the formulation of aquatic effects-based sediment-quality criteria and human risk-assessment guidelines. However, BSAF values did exhibit a significant, nonlinear decrease with increasing log Kow and with sediment and crab PCDD/F concentrations. The correlation between BSAFs and sediment concentrations accounts for between 14 and 81% of the variability in the BSAF values. The PCDD/F congeners that are present in low concentrations and/or have reduced bioavailability are the congeners that have the strongest correlations between the BSAFs and the sediment PCDD/F concentrations. Congeners that are bioavailable to Dungeness crab exhibit poorer correlations between the BSAFs and sediment concentrations.