bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methylmercury chloride and selenomethionine interactions on health and reproduction in mallards
Authors: Heinz Gary H , Hoffman David J 
Published: March 2010

Abstract
Adult mallards (Anas platyrhynchos) were fed a control diet or diets containing 10 ppm mercury as methylmercury chloride, 10 ppm selenium as seleno-DL-methionine, or 10 ppm mercury plus 10 ppm selenium. One of 12 adult males fed 10 ppm mercury died, and eight others suffered paralysis of the legs by the time the study was terminated. However, when the diet contained 10 ppm selenium in addition to the 10 ppm mercury, none of 12 males became sick. In contrast to the protective effect of selenium against mercury poisoning in males, selenium plus mercury was worse than selenium or mercury alone for some measurements of reproductive success. Both selenium and mercury lowered duckling production through reductions in hatching success and survival of ducklings, but the combination of mercury plus selenium was worse than either mercury or selenium alone. Controls produced an average of 7.6 young per female, females fed 10 ppm selenium produced an average of 2.8 young, females fed 10 ppm mercury produced 1.1 young, and females fed both mercury and selenium produced 0.2 young. Teratogenic effects also were worse for the combined mercury plus selenium treatment; deformities were recorded in 6.1% of the embryos of controls, 16.4% for those fed methylmercury chloride, 36.2% for those fed selenomethionine, and 73.4% for those fed methylmercury chloride and selenomethionine. The presence of methylmercury in the diet greatly enhanced the storage of selenium in tissues. The livers of males fed 10 ppm selenium contained a mean of 9.6 ppm selenium, whereas the livers of males fed 10 ppm selenium plus 10 ppm mercury contained a mean of 114 ppm selenium. However, selenium did not enhance the storage of mercury. The results show that mercury and selenium may be antagonistic to each other for adults and synergistic to young, even within the same experiment.
Surface binding of contaminants by algae: Consequences for lethal toxicity and feeding toDaphnia magnastraus
Authors: Taylor Graeme , Baird Donald J , Soares Amadeu M.V.M 
Published: March 2010

AbstractFreshwater algae, as with all suspended particulate matter in the water column, exhibit a net negative charge resulting in an affinity for positively charged species, such as toxic metal cations, which will readily adsorb to algal cell surfaces. In this study, the adsorption of a representative toxic metal cadmium cation (Cd2+) to a freshwater algal species, Chlorella vulgaris, was investigated using environmentally realistic concentrations of both. A further study of the effects of this particulate adsorption of Cd2+ on lethal toxicity and feeding in Daphnia magna was conducted. Two apparently contrasting effects were observed. For the D. magna feeding study, cell ingestion was inhibited, leading to reduced growth and reproduction. Experiments comparing the effect of algal-bound cadmium and dissolved forms of cadmium demonstrate that this inhibition is almost entirely due to the surface-bound fraction of ions. However, at concentrations of dissolved cadmium that are lethal to Daphnia, algal cells were found to reduce toxicity. Such findings indicate the importance of food ration in laboratory-based toxicity tests as well as the difficulty in predicting the environmental fate and effect of contaminants using such tests.
Comparisons of sediment toxicity with predictions based on chemical guidelines
Authors: Connor Thomas P O , Daskalakis Kostas D , Hyland Jeffrey L , Paul John F , Summers J Kevin 
Published: March 2010

AbstractThe U.S. Environmental Protection Agency (EPA) Environmental Monitoring and Assessment Program–Estuaries and the National Oceanic and Atmospheric Administration Bioeffects Surveys provide large data sets with which to test proposed relationships between sediment chemistry and toxicity. We conclude that guidelines based on bulk chemistry can provide useful triggers for further analysis but should not be used alone as indicators of toxicity. The sediment quality criteria for nonionic organic compounds proposed by the EPA are exceeded in so few samples that they may be of limited practical value. Toxicity was present in many cases when acid-volatile sulfide (AVS) concentrations exceeded the sum of concentrations of sulfide-insoluble metals. However, there is no way to test whether that toxicity was due to those trace elements. The AVS criterion is much more sensitive to AVS concentration than to trace metal contamination.
Reproductive success in rainbow trout following parental transfer of 2,3,4,7,8-pentachlorodibenzofuran
Authors: Delorme Peter D , Brown Scott B , Muir Derek C.G , Evans Robert E , Lockhart W Lyle , Ward Frederick J 
Published: March 2010

Abstract
Broods stock rainbow trout were intraperitoneally injected with corn oil containing a nominal dose of 0 or 3 μg [14C]2,3,4,7,8-pentachlorodibenzofuran (P5CDF)/kg (8.8 nmol/kg). The fish were held on a light cycle designed to induce spawning 10 months later. Eggs were expressed from individual ripe females and divided into two lots. One lot from each control female (Fc) and treated female (Ft) was fertilized by a treated male (Mt) and the other by a control male (Mc). Radioactivity levels were determined in parental muscle, gonads, eggs, embryos, and fry. Mean concentrations in dorsal muscle tissue were 604 pg/g (1.77 pmol/g) in treated females (Ft) and 868 pg/g (2.54 pmol/g) in treated males. No differences were found between treated and control fish, in fecundity, or in fertilization rates between any of the crosses. Concentrations of P5CDF in eggs at the time of spawning ranged from 68 to 443 pg/g wet weight with a mean concentration (N = 7) of 232 pg/g (0.68 pmol/g). Average prehatch mortalities, posthatch survival, or survival through swim-up, and the first 21 d of feeding were not different between the cross groups. Within the Ft × Mt cross group, fertilization mortality, prehatch mortality, and total mortality were significantly correlated with egg concentrations of P5CDF. Marginal but significant increases in the incidence of blue-sac-like disease occurred in the groups from treated females.
Reductive dechlorination of preexisting sediment polychlorinated biphenyls with long-term laboratory incubation
Authors: Sokol Roger C , Bethoney Charlotte M , Rhee G-Yull 
Published: March 2010

AbstractAbstract—The dechlorination potential of polychlorinated biphenyl (PCB)-contaminated sediments from the St. Lawrence River was investigated in laboratory incubations over a 39-month period. During the first 4 months, dechlorination reduced the average total chlorines in the General Motors 001 sediments from 3.2 to 2.5 per biphenyl, an additional 22% beyond the in situ level, for an overall 36% reduction from the original Aroclor 1248 contaminant. With continued incubation, however, an additional dechlorination of a single peak 2,4′,5+2,4,4′-chlorobiphenyl ensued after a lag that reduced the average chlorines from 2.5 to 2.4. After this, there was no further transformation until the end of incubation. The extent of dechlorination and congener pattern of Aroclor 1248-spiked sediments were similar to those of the native sediments after a comparable period of time despite differences in sediment sources and starting congener composition. The results indicate that most dechlorination occurs during a relatively short period of the initial rapid phase and any further transformation, if it occurs, would be extremely slow, and its contribution to the total dechlorination may not be significant.
Chlorinated hydrocarbon contaminants and productivity of bald eagle populations on the Pacific coast of Canada
Authors: Elliott John E , Norstrom Ross J 
Published: March 2010

AbstractFrom 1991 to 1995, we studied bald eagle populations breeding near three pulp mills in the Strait of Georgia, in the Fraser River estuary, and at remote reference sites on the west coast of Vancouver Island, northern Johnstone Strait, and the Queen Charlotte Islands (Haida Gwaii). Our objective was to determine occupancy of breeding territories, measure nest success, and compare the results to chlorinated hydrocarbon levels in eggs and in nestling plasma samples. Blood samples were collected in 1993 and 1994 from 52 nestlings in 38 nests and plasma analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), organochlorine (OC), pesticides, and lipid content. Most measured compounds partitioned with plasma lipids, with the exception of hepta- and octachlorinated dioxins and furans. Because of significant variation in plasma lipid content among sites, contaminant concentrations were adjusted using analysis of covariance (ANCOVA). Mean concentrations of 2,3,7,8-substituted PCDDs, PCDFs, and calculated international toxic equivalents (I-TEQs) in nestling plasma were highest in samples from near pulp mills on southeast Vancouver Island (Nanaimo and Crofton) and Powell River. Mean total PCB concentrations were also highest in the industrialized Strait of Georgia region, such as at Powell River (56 μg/kg), while OC pesticide concentrations, including 1,1-dichloroethylene bis(p-chlorophenyl) (DDE), did not vary significantly among sites. Nest success was followed for 5 years at 250 breeding territories in the nine study areas. Average productivity was higher at most study sites around the Strait of Georgia compared to the reference areas. There were no significant relationships between productivity and I-TEQs or any tetrachlorodibenzo-p-dioxin-like compounds for the whole data set; only DDE in plasma was weakly related to productivity. Likewise, there were no significant relationships between individual nest productivity and contaminant levels in eggs, based on previously published data. We also tested for variability within study areas by comparing productivity at nests adjacent to dioxin fishery closure areas at three pulp mills compared to nearby nests outside the closure areas. At two pulp mill sites, Powell River and Nanaimo, there were no differences in productivity; however, at Crofton, average productivity, 0.26 young/occupied territory, was significantly lower at nine bald eagle territories adjacent to a dioxin—fishery closure zone compared to eight territories outside of the closure area, 1.0 young/occupied territory. The cause of the low reproductive rate at Crofton has not been determined, although a toxicological explanation has not been ruled out.
Development of a continuous-flow renewal system for sediment toxicity testing
Authors: Dan Wall V , London Jack , Warren Jim E , Gossett Ron , Wenholz Michael D , Klaine Stephen J 
Published: March 2010

AbstractDevelopment of a flow-through system for sediment toxicity testing has been difficult in part because of problems associated with the precision, and subsequent expense, necessary to create a pump that accurately delivers small amounts of overlying water. This article describes a novel continuous flow-through apparatus designed to quantitatively and continuously deliver small amounts of overlying water to individual test chambers. This system uses a series of motor-driven pistons, similar to bicycle pumps, to accurately (∼5% variability) deliver small amounts of overlying water (&lt;0.1 ml/min) to individual beakers. The system can deliver more than 3.5 L of replacement fluid in a 24-h period from a single outlet hose. Different solutions can be simultaneously delivered to selected beakers, allowing researchers to study effects of water quality parameters on sediment toxicity. Materials for the system are affordable, but construction requires technical assistance. Detailed schematics to aid in construction of this system are available on the Internet at http://www.clemson.edu/entox or from the corresponding author. Water quality and the growth and survival of Chironomus riparius in clean sediments were tested under conditions of continuously and intermittently renewed overlying water. Both methods of renewal maintained acceptable average dissolved oxygen levels (&gt;70% of saturation), but an average daily range of 0.685 and 1.67 mg/L dissolved oxygen in continuous and intermittent renewal systems, respectively, was observed. No differences were observed in midge survival between continuous and intermittent renewal, but there was a 33% decrease in growth (dry weight) of C. riparius in test chambers subjected to intermittent renewal.
Evaluation of sediment slurry microcosms for modeling microbial communities in estuarine sediments
Authors: Kurtz Janis C , Devereux Richard , Barkay Tamar , Jonas Robert B 
Published: March 2010

Abstract
Microcosms consisting of estuarine sediment slurries were examined for their utility as models for assessing effects on microbial community structure and function. Data were obtained over a 2-week period to evaluate the reproducibility between individual microcosms and the variability between microcosm slurries and fresh sediment cores. Sulfate reduction rates in microcosm slurries did not differ significantly from rates for freshly collected sediment cores (p ≥ 0.05). However, the measured rates were more variable in microcosm slurries (SE = ±0.03–0.25 nM/ml/h) than in freshly collected sediments (SE = ±0.01–0.12 nM/ml/h). Rates of dark CO, fixation in the microcosm slurries declined but were consistent with rates in freshly collected sediments (6.51 and 9.29 nM/ml/h on day 3, respectively). Relative abundances (RAs) of 16S rRNA determined for six specific phylogenetic assemblages of sulfate-reducing bacteria were reproducible among three microcosm replicates with Desulfovibrio spp. consistently in greatest abundance (RA = 8.61 ± 1.40, day 7). Total direct bacterial counts were not significantly different between freshly collected sediments and microcosm slurries (p ≥ 0.05). The results indicated that microcosms were both reproducible and representative of the field, and could thus provide a potentially useful tool for studies of microbial community response to perturbation.
Toxicity of permethrin toChironomus ripariusin artificial and natural sediments
Authors: Fleming Rachel J , Holmes Dawn , Nixon Samantha J 
Published: March 2010

AbstractStandard sediments are required for prospective risk assessments so that comparable fate and effects data can be generated within and between laboratories. One approach is to use artificial media that can be easily reproduced and characterized. However, a concern is that these media may not simulate natural sediments in terms of binding and toxicological properties. In this study, the acute and chronic effects of permethrin were compared in two artificial and one natural sediment using larvae of the midge Chironomus riparius. The influence of clay and carbon content and organic matter type on permethrin toxicity was also investigated. The toxic response measured in natural sediment was lower than that in the two artificial sediments, one of which contained peat and the other which contained α-cellulose as the organic carbon source. Of the two, the peat-based medium gave a more comparable response to the natural sediment. Acute and chronic permethrin toxicity was influenced by all sediment factors investigated with a consistently lower toxicity measured in the peat-based sediment compared with the a-cellulose sediment. A decrease in toxicity, coupled with an increase in bulk sediment pemethrin concentration, was seen as both clay and organic carbon contents increased. Consideration should be given to improving the environmental realism of simple artificial formulations if the intention is to represent effects measured in natural sediments.
Confirmation of in situ exposure of fish to secondary treated bleached-kraft mill effluent using a laboratory simulation
Authors: Soimasuo Markus R , Lappivaara Jarmo , Oikari Aimo O J 
Published: March 2010

AbstractTo corroborate the responses in whitefish (Coregonus Iavaretus L.) exposed to elemental chlorine free (ECF) bleached-kraft pulp mill effluent (BKME) in situ, a 30-d laboratory exposure was carried out at concentrations simulating the field conditions. The flow-through exposures were conducted at four secondary (activated sludge) treated effluent (STE) concentrations: 1.3, 2.3, 3.5, and 7%. To evaluate the role of the secondary treatment, fish were also exposed to one concentration (3.5%) of pretreated effluent (PTE) from the mill. Compared to the control, whitefish liver 7-ethoxyresorufin-O-deethylase (EROD) activity was twofold in fish exposed to 3.5% STE, which was similar to monooxygenase induction in the field at the same effluent dilution. The exposure to 3.5% PTE caused a 12-fold relative induction in whitefish. The activity of pentoxyresorufin dealkylase showed a high correlation with EROD activity (r2 = 0.85, p &lt; 0.01). The plasma concentration of 17β-estradiol was reduced by 37% (p &lt; 0.05) in fish exposed to 3.5% STE, whereas testosterone was reduced by about 40% (p &lt; 0.05) in fish in both 3.5% STE and PTE groups. The accumulation of chlorophenolics (CPs) and resin acids (RAs) in the bile of the fish was negligible at the three lowest STE concentrations, reflecting the nearly nondetectable levels of CPs and RAs in secondary treated whole effluent. The measured blood parameters plasma immunoglobulin M, glucose, hemoglobin, and hematocrit were not affected by effluent exposure. The responses obtained from the laboratory simulation well accorded with the exposures in the field, although signs of reproductive impairment could be detected in the laboratory. Overall, however, it is evident that the improvements to mill processes and wastewater treatment have substantially reduced the load of harmful constituents in bleached-kraft mill effluent and biological impacts in the receiving environment.
Induction of cytochrome P450-associated monooxygenases in northern leopard frogs,Rana pipiens, by 3,3′,4,4′,5-Pentachlorobiphenyl
Authors: Huang Yue-wern , Melancon Mark J , Jung Robin E , Karasov William H 
Published: March 2010

AbstractNorthern leopard frogs (Rana pipiens) were injected intraperitoneally either with a solution of polychlorinated biphenyl (PCB) 126 in corn oil at a concentration of 0.2, 0.7, 2.3, or 7.8 mg/kg body weight or with corn oil alone. Appropriate assay conditions with hepatic microsomes were determined for four cytochrome P450-associated monooxygenases: ethoxyresorufin-O-dealkylase (EROD), methoxy-ROD (MROD), benzyloxy-ROD (BROD), and pentoxy-ROD (PROD). One week after PCB administration, the specific activities of EROD, MROD, BROD, and PROD were not elevated at doses ≤0.7 mg/kg (p &gt; 0.05) but were significantly increased at doses ≥2.3 mg/kg compared to the control groups (p &lt; 0.05). The increased activities of these four enzymes were 3 to 6.4 times those in the control groups. The increased activities were maintained for at least 4 weeks. Because of a lack of induction at low doses of PCB 126, which were still relatively high compared to currently known environmental concentrations, we suspect that EROD, MROD, BROD, and PROD activities are not sensitive biomarkers for coplanar PCB exposure in leopard frogs.
Annual sex steroid profiles and effects of gender and season on cytochrome P450 mRNA induction in atlantic tomcod (Microgadus tomcod)
Authors: Williams P James , Courtenay Simon C , Wilson Connie E 
Published: March 2010

AbstractAs a preliminary step in a 4-year biomonitoring program, sex steroid levels (testosterone and 11-ketotestosterone in males, and testosterone and estradiol in females), gonad weights, and diameter of vitellogenic oocytes were measured in tomcod collected bimonthly from the Miramichi (industrialized site) and Kouchibouguac (reference site) rivers from September 1993 to September 1994. As well as the reproductive indices, hepatic levels of cytochrome P4501A mRNA (CYP1A mRNA) were also measured. The preparatory period for spawning began in September, with maximal steroid levels in November, and spawning took place from late December to January. The CYP1A mRNA levels in female tomcod appeared inversely related to plasma steroids, with the lowest amounts of CYP1A mRNA coinciding with maximal steroids. The CYP1A mRNA levels in male tomcod did not exhibit this relationship. River–river comparisons of female tomcod showed significantly smaller vitellogenic oocytes in the Miramichi, along with lower plasma testosterone, estradiol, and relative gonad weight. Miramichi CYP1A mRNA levels were higher than Kouchibouguac in the fall but lower in the spring sample. The CYP1A mRNA–sex steroid relationship observed in this study will facilitate meaningful interpretation of data collected during the full 4-year study.
Effects of 3,3′,4,4′,5-pentachlorobiphenyl and 2,3,7,8-tetrachlorodibenzo-p-dioxin injected into the yolks of double-crested cormorant (Phalacrocorax auritus) eggs prior to incubation
Authors: Powell Debra C , Aulerich Richard J , Meadows John C , Tillitt Don E , Kelly Mary E , Stromborg Kenneth L , Melancon Mark J , Fitzgerald Scott D , Bursian Steven J. 
Published: March 2010

AbstractDouble-crested cormorant (Phalacrocorax auritus) eggs were injected with either 3,3′,4,4′,5-pentachlorobiphenyl (polychlorinated biphenyl [PCB] 126; 70-698 μg/kg egg) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 1.3-11.7 μg/kg egg) prior to incubation. These compounds were injected into the yolks of cormorant eggs collected from incomplete clutches at isolated colonies on Lake Winnipegosis, Manitoba, Canada. Eggs were incubated for approximately 26 to 28 d. After hatching the brain, bursa, heart, liver, and spleen were dissected and weighed. Torsos were preserved in formalin for examination of the gonads. Median lethal doses (LD50s) calculated from mortality data at hatching were 177 and 4.0 μg/kg egg for PCB 126 and TCDD, respectively. No significant differences were found in the incidence of developmental abnormalities in any of the treatment groups. Bursa weights were significantly less in the greatest (11.7 μg/kg egg) TCDD group compared to the vehicle control group. Spleen weights were significantly less in the 349 μg PCB 126/kg egg and the 5.4 and 11.7 μg TCDD/kg egg groups when compared to the vehicle control group. No histological alterations of the gonads were found. Hepatic ethoxyresorufin-O-deethylase activity in all PCB 126 and TCDD dose groups was significantly greater compared to the control activity. The toxic equivalency factor for PCB 126 was 0.02.
Postexposure effects of brief cadmium, zinc, and phenol exposures on freshwater organisms
Authors: Brent Robert N , Herricks Edwin E 
Published: March 2010

AbstractConventional toxicity testing has relied heavily on fixed duration continuous exposure conditions. These conditions have little relevance to the exposure conditions of many environmental pollutants, particularly the highly variable and often brief exposure regimes of episodic pollution events. This research was designed to assess the effects of brief exposures using a postexposure observation period. The common freshwater organisms Ceriodaphnia dubia, Hyalella azteca, and Pimephales promelas were exposed to a range of cadmium (Cd), zinc (Zn), and/or phenol concentrations for durations ranging from 15 to 240 min. Immobility was measured for up to 7 d after the exposure period. Results showed that organisms exposed to Cd and Zn exhibited delayed effects that resulted in increasing immobility for up to 172 h after the exposure period. Ceriodaphnia dubia, H. azteca, and P. promelas exposed to Cd for as short as 30 min exhibited 100, 95, and 85% immobility, respectively, during postexposure observation. Ceriodaphnia dubia and H. azteca exposed to Zn for as short as 30 min exhibited 100 and 30% immobility, respectively, during postexposure observation. Ceriodaphnia dubia exposed to phenol exhibited recovery of mobility after the exposure period. The presence of delayed effects or organism recovery suggests that toxicity tests used to monitor brief exposures should use environmentally relevant exposure durations and postexposure observations.