bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and confirmation of ammonia toxicity in contaminated sediments using a modified toxicity identification evaluation approach
Authors: Van Sprang Patrick A , Janssen Colin R
Published: March 2010

Toxicity identification of sediment pore waters from four sites in the Upper Scheldt (Belgium) was assessed using a simplified and discriminative toxicity identification evaluation procedure. The samples from all locations exhibited acute toxicity toward the freshwater crustacean Thamnocephalus platyurus. Toxicity was removed or considerably reduced by the cation exchange resins and air stripping at pH 11. In addition, the toxicity of the pore waters was found to be highly pH dependent. Increased toxicity was observed at higher pH levels, whereas reduced toxicity was found at lower pH levels. Based on these results, ammonia was suggested as the main toxic agent. The presence of ammonia concentrations exceeding the 24-h median lethal concentration and comparison of the toxicity characterization profiles of the pore waters with those of the suspected toxicant supported this hypothesis. Furthermore, a significant positive correlation between the observed toxicity of the pore waters and the expected toxicity (due to the presence of the suspected toxicant) confirmed ammonia as the true toxic agent. Finally, the ratio between the expected ammonia toxicity and the observed toxicity from the characterization tests was approx. 1, meaning that all or most of the observed toxicity was caused by the presence of one toxicant (i.e., ammonia). The developed toxicity identification evaluation procedure is suggested as a usefull tool for the identification and confirmation of toxicants in contaminated sediments.
Possible effects of polychlorinated biphenyls on sex determination in rainbow trout
Authors: Matta Mary Baker , Cairncross Charles , Kocan Richard M
Published: March 2010

Aqeous exposure of newly hatched rainbow trout (Oncorhynchus mykiss) larvae to Aroclor 1260 resulted in altered sex ratios and severe gonadal abnormalities in juvenile females. The proportion of females decreased from 41.9% in combined controls to 31.6 to 36.1% in groups that accumulated 2.5 μg/g Aroclor 1260 after 3-h immersions, although this decrease was not statistically significant (p = 0.057). A total of 18.2% of the females in the treatment group that accumulated 2.1 μg/g Aroclor 1260 had abnormal gonads as compared to 2.7% in combined controls (p = 0.001). Abnormalities were characterized by inconsistent or extremely limited development of oocytes. Although further work is required to validate these results, this study suggests that environmentally realistic tissue concentrations of Aroclor 1260 may disrupt sexual development in female trout.
Vitellogenin as a biomarker for xenobiotic estrogens in an amphibian model system
Authors: Palmer Brent D , Huth Leslie K , Pieto Dana L , Selcer Kyle W
Published: March 2010

A number of chemicals released into the environment have the potential to interfere with physiological and developmental processes by disrupting endocrine pathways. Among the best known of these endocrine disruptors are compounds that mimic the action of the steroid hormone 17β-estradiol. These xenobiotic estrogens are believed to pose health risks to both humans and wildlife. Our laboratories are designing in vivo bioassays for xenobiotic estrogens based on induction of the egg-yolk precursor protein vitellogenin. Vitellogenin is normally produced by the liver of adult female nonmammalian vertebrates under estrogen stimulation. In immature or male animals, which have low levels of endogenous estrogens, vitellogenin can serve as a reliable biomarker for exposure to xenobiotic estrogens. Our model system used the African clawed frog, Xenopus laevis, an ideal species for laboratory screening of endocrine disruptors. Xenopus laevis vitellogenin was purified by diethylaminoethyl (DEAE) chromatography and used to generate polyclonal antibodies in rabbits. The resulting antiserum was used to develop an enzyme-linked immunosorbent assay (ELISA) for measurement of serum vitellogenin. Frogs were exposed to compounds by immersion in order to mimic environmental exposure to aquatic contaminants. Initially, frogs were immersed in the potent estrogenic agent diethyl-stilbestrol (DES) at a concentration of 1 ppm for 11 d to test the efficacy of the immersion protocol. Diethylstilbestrol exposed animals showed substantial induction of serum vitellogenin, indicating that the frogs are capable of responding to estrogenic agents present in their aquatic environment. Vitellogenin induction was then investigated for chlordane, dieldrin, endosulfan, and toxaphene, compounds that have been shown through in vitro assays to be weakly estrogenic when administered individually but more strongly estrogenic in combination. Adult male frogs were immersed in water containing the compounds (1 ppm, 11 d), both singly and in paired combinations. Endosulfan proved toxic at this concentration. Toxaphene- and dieldrin-treated frogs showed significant levels of vitellogenin induction, while chlordane-treated animals did not differ from controls. There was no evidence of a synergistic response between any of the combinations. This research demonstrates the utility of vitellogenin as a biomarker for exposure to estrogenic agents. The assays developed could be used to screen chemicals for estrogenic properties, to test waters for the presence of estrogenic agents, or to assess wildlife exposure to environmental estrogens.
Methylmercury chloride and selenomethionine interactions on health and reproduction in mallards
Authors: Heinz Gary H , Hoffman David J
Published: March 2010

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

Freshwater 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

The 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

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

Abstract—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

From 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

Development 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 (<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 (>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

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

Standard 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

To 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 < 0.01). The plasma concentration of 17β-estradiol was reduced by 37% (p < 0.05) in fish exposed to 3.5% STE, whereas testosterone was reduced by about 40% (p < 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

Northern 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 > 0.05) but were significantly increased at doses ≥2.3 mg/kg compared to the control groups (p < 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

As 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

Double-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

Conventional 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.
Effects of storage temperature and duration on toxicity of sediments assessed by Crassostrea gigas oyster embryo bioassay
Authors: Beiras Ricardo , His Edouard , Seaman Matthias N L
Published: March 2010

The effects of temperature and duration of storage on the toxicity of estuarine sediments were investigated with the Crassostrea gigas oyster embryo bioassay. Sediments ranging from unpolluted (controls) to extremely polluted with heavy metals (>100 ppm Hg, Cu, Zn, and Pb) and total hydrocarbons (>1,000 ppm) were collected from sites in southwest France and northern Spain. Control sediments were toxic only at the highest concentrations tested and after freezing in liquid nitrogen (−196°C). Polluted sediments significantly reduced the success of oyster embryogenesis. Analysis of variance showed that the effect of storage temperature on toxicity increased with the prolongation of storage. Prolonged storage of fresh (4°C) sediments resulted in a loss of toxicity, which was more rapid in the less-polluted sediments. Deep-frozen sediments (−196°C) were highly toxic regardless of origin and storage time, and because deep-freezing causes spurious toxicity in the control samples, it cannot be recommended for toxicological studies. In the context of the assessment of sediment toxicity by embryo–larval bioassays, fresh (4°C) storage is recommended when sediments need to be stored for no longer than a few days. The advisable duration of fresh storage to avoid false-negative results is directly related to the degree of toxicity. Should the sediments require prolonged storage, freezing at −20°C appears to be the best choice.
Relationship between reproduction, sediment type, and feeding activity ofLumbriculus variegatus(Müller): Implications for sediment toxicity testing
Authors: Leppänen Matti T , Kukkonen Jussi V.K
Published: March 2010

The impact of reproduction and its interaction with sediment type on feeding activity of Lumbriculus variegatus are important because one major pathway in bioaccumulation of hydrophobic sediment-associated contaminants takes place through ingested sediment. In this study, the surface egesting behavior and the reproduction of the oligochaete were studied to understand this relationship and to give recommendations for the use of L. variegatus in sediment toxicity testing. Single individuals were used as replicates allowing proper control of reproduction behavior and egestion rate. Reproduction, growth, and egestion rates were clearly different in the two fine-grained unpolluted lake sediments used in the first 28-d experiment. The feeding of oligochaetes stopped during the reproduction process in the second 30-d experiment. Individuals divided at their middle; the anterior part took 2 d and the posterior part took 6 to 7 d to regenerate new segments and to initiate egestion. Culture conditions determined at what size the animals were able to reproduce during the test. In our tests 9 mg wet weight was the approximate minimum organism size needed for reproduction behavior. Recommendations for sediment toxicity and bioaccumulation testing using L. variegatus include using the largest oligochaetes in culture if reproduction is the endpoint and using recently fragmented individuals with complete segments if animals are employed in bioaccumulation tests.
Heavy metals in bullfrog (Rana catesbeiana) tadpoles: Effects of depuration before analysis
Authors: Burger Joanna , Snodgrass Joel
Published: March 2010

Although tadpoles may well be excellent organisms to use as bioindicators of heavy metal contamination, the relationship of deposition in the body compared to the tail, and the effect of sediments or other debris in the digestive tract on heavy metal concentrations is unknown. We examined the effect of experimental depuration of bullfrog (Rana catesbeiana) tadpoles on heavy metal and selenium concentrations in intact tadpoles, as well as their bodies and tails. We defined depuration in this experiment as allowing defecation as an elimination process for intestinal contents (=clearing). We maintained wild-caught tadpoles in clean water for 0, 24, 48, and 72 h to determine the effects of clearing on heavy metal concentrations. We also examined the concentrations of heavy metals in the whole body and digestive tract separately. We test the null hypotheses that no differences occur in metals as a function of time in uncontaminated water, and that no differences occur in metal concentrations in the body compared to the tail and to the digestive tract. We rejected these hypotheses based on regression models. Variance in concentrations of chromium (77%) and lead (70%) were explained by part (body, tail, whole body) and clearing time; for manganese (80%), mercury (64%), selenium (28%), and cadmium (25%) the variation was explained only by body part; for arsenic (53%), the variation was explained by part, clearing time, and weight of the various parts. For those metals in which clearing time explained part of the variation, metal concentrations in both the body and tail decreased after 24 and 48 h, but increased slightly thereafter. Clearing, however, did not greatly decrease metal concentrations in either the body or tail. These data suggest that for some metals (mercury, manganese, cadmium, selenium), clearing has no effect, and for others the effect is slight. For fresh tadpoles, however, the digestive tract contained significantly higher concentrations of all metals than either the body or head, probably reflecting metals absorbed to sediment particles in the gut.
Effect of zeolite on toxicity of ammonia in freshwater sediments: Implications for toxicity identification evaluation procedures
Authors: Besser John M , Ingersoll Christopher G , Leonard Edward N , Mount David R
Published: March 2010

Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation (TIE) procedures for whole sediments. Although ammonia is a natural constituent of freshwater sediments, pollution can lead to ammonia concentrations that are toxic to benthic invertebrates, and ammonia can also contribute to the toxicity of sediments that contain more persistent contaminants. We investigated the use of amendments of a natural zeolite mineral, clinoptilolite, to reduce concentrations of ammonia in sediment pore water. Zeolites have been widely used for removal of ammonia in water treatment and in aqueous TIE procedures. The addition of granulated zeolite to ammonia-spiked sediments reduced pore-water ammonia concentrations and reduced ammonia toxicity to invertebrates. Amendments of 20% zeolite (v/v) reduced ammonia concentrations in pore water by ≥70% in spiked sediments with ammonia concentrations typical of contaminated freshwater sediments. Zeolite amendments reduced toxicity of ammonia-spiked sediments to three taxa of benthic invertebrates (Hyalella azteca, Lumbriculus variegatus, and Chironomus tentans), despite their widely differing sensitivity to ammonia toxicity. In contrast, zeolite amendments did not reduce acute toxicity of sediments containing high concentrations of cadmium or copper or reduce concentrations of these metals in pore waters. These studies suggest that zeolite amendments, used in conjunction with toxicity tests with sensitive taxa such as H. azteca, may be an effective technique for selective reduction of ammonia toxicity in freshwater sediments.
Subchronic and reproductive toxicity of emamectin benzoate to mallard ducks and northern bobwhite quail
Authors: O'Grodnick Joseph S , Wislocki Peter G , Keenan Kevin P , Beavers Joann B , Frey Larry T , Jaber Mark
Published: March 2010

Avian reproduction studies were performed in both the mallard and the northern bobwhite. Emamectin benzoate was incorporated into the diets of the two avian species prior to and during a period of reproduction. Mallards were exposed at dietary concentrations of 0, 4, 8, 20, or 40 ppm of emamectin benzoate for 20 weeks, whereas northern bobwhites were exposed to dietary concentrations of 0, 4, 13, 40, or 125 ppm of emamectin benzoate for 22 weeks. Birds were monitored for body weight, feed consumption, general health, and reproductive parameters. At the end of the reproduction period, all adult birds were examined for gross morphologic changes, and adult birds in the high-dose concentration groups were examined for neuropathologic effects. No treatment-related mortalities, overt signs of toxicity, or treatment-related effects on adult body weight or feed consumption occurred at any of the concentrations tested in either species. No treatment-related effects were observed upon any of the reproductive parameters measured. Emamectin benzoate did not induce gross or light microscopic lesions in the brain, spinal cord, or peripheral nerves to the level of the distal branches of the sciatic nerve, including the tibial nerve, in either the mallard or northern bobwhite. The no observed effect concentrations for mallards and northern bobwhites exposed to emamectin benzoate in the diet were 40 ppm and 125 ppm, respectively.
Toxicity of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin to early life stage brook trout (Salvelinus fontinalis) following parental dietary exposure
Authors: Johnson Rodney D , Tietge Joseph E , Jensen Kathleen M , Fernandez Joseph D , Linnum Ann L , Lothenbach Douglas B , Holcombe Gary W , Cook Philip M , Christ Suzanne A , Lattier David L , Gordon Denise A
Published: March 2010

The toxicity of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) to the early life stages of F1 generation brook trout (Salvelinus fontinalis) was determined, when dosed by maternal transfer. Effects were compared across six treatments, including a control. The experimental groups, based on TCDD concentrations in freshly spawned eggs (control, 41, 84, 156, 285, and 517 pg TCDD per gram egg [wet weight]), were established by treating 1.5-year-old brook trout with TCDD-dosed food throughout the period beginning with final gonadal maturation and continuing until just prior to spawning. Measurement endpoints assessed at various times throughout the study, included (1) TCDD and lipid concentrations in ovaries, eggs, alevins, and juvenile fish, (2) mortality, (3) fertility indices, (4) growth, (5) juvenile sex ratios, (6) pathology, and (7) cytochrome P4501A1 mRNA (CYPIA1) levels in embryos. The cumulative lethality dose response was determined just prior to hatch, at swim-up, and at the end of the study. The concentration in eggs causing 50% mortality (LCegg50) at swim-up and at the end of the study were 138 and 127 pg TCDD per gram egg, respectively. No treatment effects were observed on fertility, growth, or juvenile sex ratios. Pathologies were observed that have been previously reported in TCDD-exposed salmonid embryos, including edema in free embryos from all TCDD-exposed treatment groups at hatch. At the end of the test, juvenile fish from all treatments exhibited an increased prevalence of exophthalmia compared to the controls. The ECegg50 for this effect was 117 pg TCDD per gram egg. Histological analysis of the end-of-test juveniles, in gonad, nerve, vertebrae, neuromasts, liver, kidney, gut, gas bladder, skin, and blood vessels, did not indicate any significant pathology below the LCegg50. P4501A1 mRNA levels in whole 91-d postspawn free embryos from the 84 pg TCDD per gram egg treatment were 2.8 times higher compared with control or 41-pg TCDD per gram egg treatments. Results from this study were consistent with other published results of TCDD effects on salmonids, in which the exposures occurred after fertilization.
Evaluation of aquatic toxicity and bioaccumulation of C8- and C9-alkylphenol ethoxylates
Authors: Staples Charles A , Weeks John , Hall Jerry F , Naylor Carter G
Published: March 2010

The extensive database of acute and chronic aquatic toxicity data for alkylphenol ethoxylates (APEs) and selected biodegradation intermediates was reviewed and summarized for freshwater and saltwater aquatic microorganisms, algae, invertebrates, and fish inhabiting cold and warm water bodies. Most acute toxicity studies that tested APE-9 and APE-10, the most common commercially relevant APEs, reported results that ranged from about 1,000 to 10,000 μg/L. Results from studies testing alkylphenols, intermediate by-products of APE biodegradation, ranged from about 20 to 3,000 μg/L. Chronic values are a factor of about 2 to 10 lower. Although most studies used one of several common species and standard protocols to assay conventional endpoints, many nontraditional species and toxicological endpoints were also used. This toxicological database encompasses virtually all important types of aquatic habitats and classes of aquatic species. Bioaccumulation data from both laboratory and field studies indicate that alkylphenols have a low to moderate bioaccumulation potential. Fresh weight, nonlipid-based bioconcentration factors (BCFs) measured in the laboratory ranged from < 1 to 1,250 for fish and 1 to 3,400 for invertebrates, whereas field bioaccumulation factors (BAFs) ranged from 6 to 487, with most values < 100. Overall, these data provide an extensive and useful database to support environmental risk assessment activities.
Bioaccumulation and toxicity of silver compounds: A review
Authors: Ratte Hans Toni
Published: March 2010

A eview of the literature revealed that bioaccumulation of silver in soil is rather low, even if the soil is amended with silver-containing sewage sludge. Plants grown on tailings of silver mines were found to have silver primarily in the root systems. In marine and freshwater systems, the highest reported bioconcentration factors (BCFs) were observed in algae (>105), probably because of adsorption of the dissolved silver (<0.45 μm fraction) to the cell surface. In herbivorous organisms (e.g., zooplankton and bivalves), the BCF was lower by about two orders of magnitude. Low amounts of silver were assimilated from food with no substantial biomagnification. In carnivores (e.g., fish), the BCF was also lower by one order of magnitude with no indication of biomagnification. Toxicity of silver occurs mainly in the aqueous phase and depends on the concentration of active, free Ag+ ions. Accordingly, many processes and water characteristics reduce silver toxicity by stopping the formation of free Ag+, binding Ag+, or preventing binding of Ag+ to the reactive surfaces of organisms. The solubility of a silver compound, and the presence of complexing agents (e.g., thiosulfate or chloride), dissolved organic carbon, and competing ions are important. In soil, sewage sludge, and sediments, in which silver sulfide predominates, the toxicity of silver, even at high total concentrations, is very low. The highly soluble silver thiosulfate complex has low toxicity, which can be attributed to the silver complexed by thiosulfate. Silver nitrate is one of the most toxic silver compounds. The toxic potential of silver chloride complexes in seawater is and will be an important issue for investigation. Aquatic chronic tests, long-term tests, and tests including sensitive life stages show lower toxicity thresholds (˜1 μg Ag+/L). The organisms viewed as most sensitive to silver are small aquatic invertebrates, particularly embryonic and larval stages.
Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests
Authors: Kemble Nile E , Dwyer F James , Ingersoll Christopher G , Dawson Timothy D , Norberg-King Teresa J
Published: March 2010

A method is described for preparing formulated sediments for use intoxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and α-cellulose (as a source of organic carbon). α-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca, the midges Chironomus riparius and C. tentans, and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca. Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of α-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in 28-d exposures, consistent responses of amphipods were observed in both formulated and control sediments.