bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dietary accumulation of C12- and C16-chlorinated alkanes by juvenile rainbow trout (Oncorhynchus mykiss)
Authors: Fisk Aaron T. , Bergman ÅKe , Cymbalisty Chris D. , Muir Derek C. G. 
Published: March 2010

Abstract
Dietary exposures using juvenile rainbow trout (Oncorhynchus mykiss) were conducted with four 14C-polychlorinated alkanes (C12H20Cl6 [56% Cl by weight], C12H16Cl10 [69% Cl], C16H31Cl3 [35% Cl], and C16H21Cl13 [69% Cl]) in order to measure bioaccumulation parameters, metabolism, and tissue distributions. These chlorinated alkanes are found in industrial chlorinated paraffin (CP) products, although their method of synthesis is different than that of CPs. Trout were exposed for 40 d to nominal concentrations of 20 and 200 ng/g of each chlorinated alkane, as well as to 2,000 ng/g for C16H21Cl13, followed by an elimination period of up to 173 d. Whole-body half-lives in the rainbow trout ranged from 37 ± 2 d for C16H31Cl3 to 87 ± 11d for C12H16Cl10, and assimilation efficiencies of C16H31Cl3 (33 to 35%) and C12H16Cl10 (34 to 38%) were highest among the four alkanes. Biomagnification factors ranged from 0.44 for C16H21Cl13 to 2.15 for C12H16Cl10. Accumulation of C16H21Cl13 (molecular weight = 674) may be sterically hindered due to its large molecular size. Lower chlorinated alkanes, e.g., C16H31Cl3, had shorter half-lives than highly chlorinated alkanes, probably due to increased metabolism. High-performance liquid chromatography 14C analysis offish tissue extracts revealed that the chlorinated alkane mixtures were selectively biotransformed with certain unknown components persisting in tissues. Lower chlorinated alkanes had greater proportions of polar 14C, which implies greater metabolism of these compounds. Highly chlorinated, short-carbon-chain (C10–13) alkanes and lower chlorinated, medium-carbon-chain (C14–18) alkanes appear to have the greatest potential for biomagnification among CP components. No reduced growth rates or hepatic monooxygenase enzyme induction were seen in any of the chlorinated alkane exposures when compared with controls.
Investigations of enzymatic alterations of 2,4-dichlorophenol using 13C-nuclear magnetic resonance in combination with site-specific 13C-labeling: Understanding the environmental fate of this pollutant
Authors: Nanny Mark A. , Bortiatynski Jacqueline M. , Hatcher Patrick G. , Tien Ming 
Published: March 2010

Abstract
The biodegradation of 13C-labeled 2,4-dichlorophenol (DCP labeled at the C-2 and C-6 positions), in the presence and absence of natural organic matter (NOM), by the white-rot fungus Phanerochaete chrysosporium, was examined using 13C-nuclear magnetic resonance (NMR). Using this method permitted the chemistry occurring at or near the labeled site to be followed. The formation of alkyl ethers and alkene ethers was observed. No aromatic by-products were detected, indicating that aromatic compounds are quickly degraded. Examining the reaction with time shows the exponential removal of 2,4-DCP and the consequential formation of labeled by-products, whose concentration reaches a maximum just before all 2,4-DCP is consumed. After this, the by-products degrade exponentially. The presence of NOM causes 2,4-DCP to be removed from the aqueous phase more quickly than in its absence and also causes the by-products to reach their maximum concentration much earlier. Degradation of the by-products occurs at a much greater rate in the presence of NOM. One hypothesis for this behavior is that the NOM interacts with 2,4-DCP and its by-products, allowing them to be incorporated into the fungal biomass. 13C-nuclear magnetic resonance spectra of the fungal biomass after NaOH extraction show the presence of alkanes and a small amount of 2,4-DCP.
Limited bioavailability of sediment pah near an aluminum smelter: Contamination does not equal effects
Authors: Paine Michael D. , Chapman Peter M. , Allard Patrick J. , Murdoch Mary H. , Minifie David 
Published: March 2010

Abstract
A Sediment Quality Triad study involving synoptic measures of polycyclic aromatic hydrocarbon (PAH) contamination, toxicity, and resident community (benthic infauna, crab) alteration was conducted to assess impacts from an aluminum smelter discharge. No sediment toxicity was observed, despite extensive testing since 1988 on four test species. Evidence of effects on resident communities was minimal. Effects were not expected in areas &gt;1 km from the smelter, because PAH concentrations have decreased with recent effluent improvements to below levels associated with effects in other studies. However, concentrations within 1 km of the smelter were high (maximum concentration was 10,000 mg/kg total PAH, although most were &lt;150 mg/kg). Based on the literature, those concentrations should have had significant effects on toxicity test responses and benthic communities. Because they did not, we conclude that availability of sediment PAH was limited. Concentrations of parent PAH and metabolites in Dungeness crab (Cancer magister) were also low, supporting the hypothesis of limited bioavailability. Bioavailability may be limited because much of the PAH is present as pitch or coal particles. This study indicates that high contaminant concentrations may not be associated with effects, if availability is limited.
Bioavailability and chronic toxicity of cadmium in sediment to the estuarine amphipodLeptocheirus plumulosus
Authors: Dewitt Theodore H. , Swartz Richard C. , Hansen David J. , McGovern Douglas , Berry Walter J. 
Published: March 2010

AbstractNumerous studies have demonstrated the efficacy of interstitial water metal concentrations and simultaneously extracted metals/acid-volatile sulfide (SEM/AVS) ratios in explaining the acute toxicity of sediment-associated metals to benthic organisms. However, no full life-cycle chronic marine or estuarine tests have been conducted for this purpose. In this study, cohorts of newborn amphipods, Leptocheirus plumulosus, were exposed to cadmium-spiked estuarine sediment for 28 d to determine effects on mortality, growth, and reproduction relative to interstitial water and SEM/AVS normalization. Seven treatments of cadmium were tested: 0 (control), 0.34, 0.74, 1.31, 1.55, 2.23, and 4.82 M SEMcd/AVS ratios (measured concentrations). Interstitial water cadmium (IWcd) and sediment concentrations of SEMcd and AVS were monitored periodically and by depth during the exposure. When sediment SEMcd/AVS ratios were ≤1.55, mean IWcd concentrations were less than the 96-h water-only cadmium LC50 for juvenile and subadult L. plumulosus, and mortality, growth, and reproduction were not affected. When SEMcd/AVS ratios were ≥2.23, IWcd concentrations were more than 100 times greater than the 96-h water-only cadmium LC50, and all amphipods died. These results are consistent with predictions of metal bioavailability from acute tests with metal-spiked sediments, i.e., that sediments with SEMcd/AVS ratios &lt;1 are not toxic, while sediments with SEMcd/AVS ratios &gt;1 may be toxic.
TCDD-Like activity of 2,3,6,7-tetrachloroxanthene in rainbow trout early life stages and in a rainbow trout gonadal cell line (RTG-2)
Authors: Zabel Erik W. , Peterson Richard E. 
Published: March 2010

Abstract
Fish in many areas are contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and biphenyl (PCB) congeners. Other chemicals may also be present that act through the same mechanism. 2,3,6,7-Tetrachloroxanthene (TCX) has been found to be an interference in PCDD and PCDF analyses and may occur in sediments near pulp and paper mills. However, the toxicology of TCX has not been studied in any species. This study sought to determine whether TCX causes TCDD-like effects in two fish systems, rainbow trout early life stages and rainbow trout gonadal cells (RTG-2) in culture. 2,3,6,7-Tetrachloroxanthene caused rainbow trout sac fry mortality secondary to blue sac syndrome, identical to that caused by TCDD, and was similar in potency to TCDD for causing cytochrome P4501A mRNA induction in RTG-2 cells and sac fry mortality in rainbow trout, with toxic equivalency factors of 1.09 to 2.29. These results suggest that TCX may pose a risk to feral fish in contaminated areas even at low concentrations.
Comparative evaluation of soil toxicity using lettuce seeds and soil ciliates
Authors: Bowers Nancy , Pratt James R , Beeson David , Lewis Mark 
Published: March 2010

Abstract
The toxicity of elutriates from 25 putatively contaminated soils was evaluated using the standard seed (Lactuca sativa) germination test and a recently developed soil ciliate (Colpoda inflata) growth test. Correspondence in the identification of presence or absence of toxicity in the 25 soil elutriates between the two tests was 60% and concordance in ranking of toxicity between the two tests was significant (p &lt; 0.05) using Spearman's rank correlation test (rs = 0.3831). Stepwise multiple regression analysis of toxicity results against soil elutriate chemistry indicated that pH explained the greatest amount of variation in response in both tests, despite high concentrations of several metals in the elutriates. For the germination test, a multiple regression model that included pH and cadmium explained 58.5% of response variation, whereas over 83% of response variation in the ciliate growth test could be explained by pH, copper, and cadmium. Differences in the response of the plant and protozoan models appeared to be due primarily to differences in their sensitivity to elutriate pH. In addition to better correspondence between elutriate chemistry and ciliate response compared to the seed germination test, lower response variability associated with the measure of ciliate growth compared with seed germination provided greater statistical sensitivity for detecting toxic effects.
Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on development of anuran amphibians
Authors: Jung Robin E , Walker Mary K 
Published: March 2010

AbstractWe exposed anuran eggs and tadpoles to vehicle control (0.7% acetone) or waterborne [3H]2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for 24 h (American toad, 0.003-30 μg/L; leopard frog, 3 μg/L; green frog, 0.3-100 μg/L) and subsequently raised them in clean water. Neither American toads nor green frogs exhibited TCDD-related mortality, but leopard frogs showed significantly increased (10%) mortality over controls. Eggs and tadpoles eliminated TCDD relatively quickly compared with published data for other vertebrates, with t1/2 of 1 to 5 d (American toad), 2 to 7 d (leopard frog), and 4 to 6 d (green frog). Elimination rates were slowest for tadpoles fed nothing, fastest for those fed a low-fat diet, and intermediate for those fed a high-fat diet. Although not significant, American toads exposed to ⩾0.03 μg TCDD/L appeared to metamorphose earlier, and those exposed to higher TCDD treatments appeared to metamorphose at a larger body mass than controls. Comparisons of these results with studies of fish early life stages suggest that anuran eggs and tadpoles eliminate TCDD more rapidly and are 100- to 1,000-fold less sensitive to its deleterious effects during development. These differences may be related to differences in metabolic rate, patterns of lipid storage and utilization, and aryl hydrocarbon receptor binding and signal transduction.
Ecotoxicological assessment of aquatic sediments withCaenorhabditis elegans(nematoda) — a method for testing liquid medium and whole-sediment samples
Authors: Traunspurger Walter , Haitzer Markus , Höss Sebastian , Beier Stefanie , Ahlf Wolfgang , Steinberg Christian 
Published: March 2010

AbstractWe present a method using the free-living nematode Caenorhabditis elegans (Maupas, 1899) to assess toxicity in liquid medium and whole-sediment setups. Test duration is 72 h; endpoints are body length, number of eggs inside worms, percentage of gravid worms, and number of offspring per worm. The effect of CdCl2 on C. elegans in liquid-phase exposures is described as an example. Results from a field study with polluted sediments from the River Elbe (Germany) suggest that nematodes may be useful organisms in assessing toxicity of sediments in the whole phase.
Effects of exposure to an organophosphate pesticide on behavior and acetylcholinesterase activity in the common shrew, Sorex araneus
Authors: Dell'Omo Giacomo , Bryenton Rachel , Shore Richard F 
Published: March 2010

Abstract
The behavioral and physiological effects of exposure to dimethoate, an organophosphate (OP) pesticide, were examined in common shrews, Sorex araneus, under laboratory conditions. Shrews were given either saline or an acute sublethal dose (50 mg/kg intraperitoneal) of dimethoate, and a time course of behavior was recorded in five 10-min open field tests spaced over a 12-h period. Parallel measurements of brain acetylcholinesterase (AChE) activity were carried out to monitor the onset of brain AChE inhibition and its subsequent recovery. Dimethoate produced a significant depression of locomotor activity for approx. 6 h. Rearing, exploring, and sniffing activities were also significantly inhibited. The observed behavioral effects coincided with the maximal inhibition of AChE and disappeared before the brain AChE level had recovered. Statistically significant correlations were observed between the reduced frequencies of exploring, rearing, and crossings (a measure of locomotor activity) and the severity of inhibition of brain AChE activity, suggesting that brain AChE activity, the biomaker of exposure, could be used as a predictor of the severity of OP-induced effects on behavior.
The significance of growth inChironomus tentanssediment toxicity tests: Relationship to reproduction and demographic endpoints
Authors: Sibley Paul K , Benoit Duane A , Ankley Gerald T 
Published: March 2010

AbstractIn the Chironomus tentans 10-d growth test, changes in larval growth relative to sediment contamination are often ascribed ecological relevance by assuming that such changes become manifest at the population level through effects on reproductive output even though the relationship between growth and reproduction is poorly understood. The objective of this study was to evaluate the relationship between growth and reproduction in C. tentans and to use these data in a demographic model to predict the growth and size of a theoretical population. Growth was manipulated by varying food supply (0.29, 0.33, 0.38, 0.42, 0.46, and 0.5 mg/individual per d). The test was initiated with 12 newly hatched larvae per replicate and carried through one complete generation. Larval growth and survival were determined at 20 d, and reproduction was monitored daily during emergence. Food supply did not significantly affect survivorship at any life stage; survival of larvae at 20 d, pupae, and adults exceeded 83%, while survival of larvae in the reproduction replicates exceeded 65%. Both larval and adult dry weight declined significantly with a reduction in food supply. Total emergence was reduced at the lowest feeding level only, whereas the rate of emergence declined at food supplies below 0.42 mg/individual per d. Based on the relationship between larval and adult dry weight, a minimum larval tissue mass of between 0.5 and 0.6 mg dry weight/individual appears to be necessary before emergence can take place. The number of eggs/female declined significantly with a decrease in food supply below 0.42 mg/individual per d. Above this level (corresponding to larval dry weight of ∼ 1.5 mg/individual), the addition of more food had no effect on reproductive output. Fecundity (number of daughters/female) and expected number of progeny declined linearly with reduced food supply. Application of the data in a demographic model showed that the growth and predicted size of a population would decline significantly with a decline in larval growth and reproductive output. These results demonstrate that changes in growth, positive or negative, can be used to make meaningful predictions regarding reproduction and population dynamics in the midge C. tentans.
A method for evaluating the toxicity of industrial solvent mixtures
Authors: Kononen Douglas W , Gorski Robert A 
Published: March 2010

Abstract
The toxicity of a mixture of toluene and mixed xylenes was studied with the frog embryo teratogenesis assay—Xenopus (FETAX). Single compound experiments with either toluene or mixed xylenes show that growth inhibition, not mortality or malformation, is the most sensitive toxic endpoint in the FETAX system (i.e., growth is inhibited at lower exposure concentrations than those resulting in malformations and mortality). A multiple logistic regression analysis model described mortality and malformation as functions of exposure concentrations of toluene and mixed xylenes. The results indicate that toluene and mixed xylenes are additive in their effects on mortality in the FETAX system. Further experimentation is necessary to validate the model's ability to describe malformation as a function of coexposure to toluene and mixed xylenes.
Do mosquito control treatments of wetlands affect red-winged blackbird (Agelaius phoeniceus) growth, reproduction, or behavior?
Authors: Hanowski JoAnn M , Niemi Gerald J , Lima Ann R , Regal Ronald R 
Published: March 2010

Abstract
We found no convincing evidence that reproduction, growth, or foraging behavior of red-winged blackbirds (Agelaius phoeniceus) were negatively impacted by treatments of wetlands with either Bacillus thuringiensis israelensis (Bti, applied as Vectobac-G granules) or methoprene (applied as Altosid sand granules). Most red-winged blackbird parameters examined varied annually and some differences were found before treatments began. In all cases, differences found before treatments were either found again during the treatment years or no patterns existed to suggest impacts of mosquito control treatments. Only 1 of the 22 variables examined indicated a significant difference between a treatment group and the controls; males in Bti-treated sites were larger than males in control sites during the treatment years. Clutch size indicated a significant treatment-by-year interaction and was higher in control areas as compared with Bti-treated areas in 3 of the 6 years of study; 2 years occurred before any treatments were applied. Data from benthic aquatic insect studies showed that aquatic insects were depressed in wetlands treated with both methoprene and Bti in July and August. However, it is unlikely that food available to avian species in these wetlands was lower during the breeding season (May and June). Other portions of the avian life cycle that may be affected include the dispersal of young birds within or to these sites and individuals that use wetlands during migration. Impacts on these aspects of the avian community and landscape-level effects of treatments were not addressed.
Risk of ammonia toxicity during sediment bioassays with the estuarine amphipodLeptocheirus plumulosus
Authors: Moore David W , Bridges Todd S , Gray Brian R , Duke B Maurice 
Published: March 2010

AbstractHigh levels of ammonia in sediment toxicity tests can potentially confound test results. At issue is whether the observed toxicity is due to elevated ammonia or the presence of more persistent anthropogenic contaminants. To evaluate the risk of ammonia toxicity, information on (1) the exposure–response relationship and (2) the probability of exposure are needed. Preliminary exposure–response data were obtained for two different sieved size classes of the estuarine amphipod Leptocheirus plumulosus representing juveniles (425–600 μm) and subadults (not reproductively active) (600–1,000 μm) in 4-d water-only exposures with ammonia (NH4Cl). Resulting LC50 values were 44 (juvenile) and 89 mg NH3-N/L (subadult). Results from 4-d tests were used to establish exposure concentrations for two spiked-sediment studies: (1) a 10-d static exposure starting with subadults measuring survival and growth and (2) a 28-d exposure with daily renewal of overlying water starting with juveniles and measuring survival, growth, and reproduction. Risk of ammonia toxicity to L. plumulosus during sediment toxicity tests was characterized via a Monte Carlo simulation using the exposure–response curves from laboratory spiked-sediment studies and published porewater ammonia values for 322 marine sediments. Results indicate a significant potential for ammonia induced interference in the 10-d test (e.g., 2–18% probability of significant mortality due to ammonia alone). Risk in 28-d tests appears to be minimal due to rapid dissipation of ammonia via renewal of overlying water.
Structure-activity relationships for Pimephales and Tetrahymena: A mechanism of action approach
Authors: Bearden Anna P , Schultz T Wayne 
Published: March 2010

Abstract
The toxicity data of 74 chemicals tested in both the 96-h fathead minnow (Pimephales promelas) mortality assay and the 2-d Tetrahymena pyriformis (a protozoan) growth inhibition assay were evaluated using quantitative structure-activity relationships (QSARs). Each chemical was a priori assigned a mechanism of acute toxic action from either nonpolar narcosis, polar narcosis, weak acid respiratory uncoupling, soft electrophilicity, or proelectrophilicity. The polar narcotics were further split into a phenol group and an aniline group. The relationship between bioreactivity and the importance of penetration to the site of action in both systems was studied. Bioreactivity showed a trend to be inversely proportional to the value of the hydrophobicity term. The data were examined to investigate how different molecular descriptors modeled the mechanisms of action. Models were produced for nonpolar narcotics and anilines for both species with the 1-octanol/water partition coefficient (log Kow) alone. Soft electrophiles were best predicted by the average acceptor superdelocalizability (Snav), whereas proelectrophiles were modeled by log Kow and Snav. The weak acid uncouplers modeled with either log Kow or log Kow plus the ionization constant (pKa) for Pimephales and Tetrahymena, respectively. Phenols yielded predictive models using a either a combination of log Kow with Snav or lowest unoccupied molecular orbital, for fathead minnow and protozoan, respectively.
Effect of hybrid poplar trees on microbial populations important to hazardous waste bioremediation
Authors: Jordahl James L , Foster Lesley , Schnoor Jerald L , Alvarez Pedro J J 
Published: March 2010

Abstract
Microbial concentrations of denitrifiers, pseudomonads, and monoaromatic petroleum hydrocarbon (BTX) degraders were significantly higher (p &lt; 0.1) in soil samples from the rhizosphere of poplar trees than in adjacent agricultural soils, and atrazine degraders were found only in one rhizosphere sample. The relative abundance of these phenotypes (as a fraction of total heterotrophs) was not significantly different between rhizosphere and surrounding soils. Therefore, the poplar rhizosphere enhanced the growth of microbial populations that participate in natural bioremediation without exerting selective pressure for them.