bluuebunny/crossref_metadata_2025_split huggingface dataset:
Air-water partition constants for volatile methyl siloxanes
Authors: Kochetkov Alexander , Smith Jeffrey S , Ravikrishna Raghunathan , Valsaraj Kalliat T , Thibodeaux Louis J 
Published: March 2010

Abstract
Silicones are an important class of hydrophobic compounds in widespread use. To evaluate their fate in the environment, an accurate value of the air-water partition (Henry's law) constant is necessary, which, unfortunately, is lacking at present. A static head space and a newly developed dynamic vapor entry loop method were used to obtain the air-water partition constant for six volatile methyl siloxanes. Internally consistent data were obtained. The value of Henry's constant, as calculated from pure component vapor pressure and aqueous solubility, was 10- to 170-fold greater than the experimental values. A correction to the Henry's constant that involves the ratio of the thermodynamic activity coefficient for a methyl siloxane at infinite dilution to that at saturation solubility in the aqueous phase is proposed.
The effect of stress on toxicant-dependent cytochrome P450 enzyme responses in the arctic charr (Salvelinus alpinus)
Authors: Jørgensen Even Hjalmar , Celander Malin , Goksøyr Anders , Iwata Munehico 
Published: March 2010

AbstractIn the present study we investigated the effect of stress and cortisol on cytochrome P450 (CYP) expression in Arctic charr exposed to benzo[a]pyrene (BaP). Expression of hepatic CYP1A and CYP3A was monitored 8 d after a single oral dose of BaP (10 mg/kg fish) and compared to that in unexposed fish. During this period the fish were subjected to one of the following stress regimes: no stress, no stress and cortisol implantation, 10 min of daily handling and confinement stress, and confinement stress during the last 6 h before sampling. In BaP-exposed fish daily stress resulted in significantly lower (53%) CYP1A protein levels as compared to those in unstressed fish. For CYP1A catalytic activity (measured as 7-ethoxyresorufin-O-deethylase [EROD] activity), the suppressive response to stress was less pronounced. These results contrast to previous findings of a potentiation by corticosteroids on xenobiotic-dependent CYP1A induction in vitro in cultured fish hepatic cells. No effects of high cortisol levels or BaP were found on the steroid-metabolizing CYP3A enzyme levels. The lack of any alterations in the CYP3A protein level indicates that CYP3A expression is not inducible by cortisol in the Arctic charr under the conditions used here. The conclusion was made that short-term stress associated with sampling (i.e., 6 h of confinement stress before sampling) of wild charr does not compromise the EROD activity as a reliable biomarker.
Toxicity identification of metals: Development of toxicity identification fingerprints
Authors: Van Sprang Patrick A , Janssen Colin R 
Published: March 2010

Abstract
The ecotoxicological and chemical response of five metals (Cd, Cr, Cu, Ni, and Zn) to selective fractionation techniques was assessed using the organism Daphnia magna. The metals Cu and Zn revealed similar toxicity patterns, showing an increased toxicity when lowering the pH, a marked reduction in toxicity after addition of ethylenediaminetetraacetic acid (EDTA). Similar toxicity reductions were obtained by passing the metal solutions over ion exchangers, activated charcoal, and filtration/solid-phase extraction units at neutral and basic pHs. The discrimination between Cu- and Zn-toxicity occurred in the oxidant reduction test, i.e., Zn toxicity was not affected by the addition of Na2S2O3, while Cu toxicity was strongly reduced. A second cluster was formed by Cd and Ni. The toxicity of both metals markedly decreased in the EDTA, ion exchangers, activated charcoal, filtration, and solid-phase extraction tests at high pHs. Discrimination between the toxicity of both metals was accomplished with the graduated pH test, in which a pH-independent toxicity response was found for Ni while the toxicity of Cd increased at lower pHs. Compared with the other metals, a very distinct toxicity pattern for Cr was observed. From the applied fractionation techniques, only the graduated pH and the anion resin tests resulted in a marked change in Cr toxicity. The produced toxicity patterns for each individual metal could therefore be used as fingerprints (i.e., toxicity identification fingerprints) in order to identify the toxicity caused by individual metals for D. magna.
Acute toxicity of heavy metals to acetate-utilizing mixed cultures of sulfate-reducing bacteria: EC100 and EC50
Authors: Utgikar Vivek P , Chen Bor-Yann , Chaudhary Navendu , Tabak Henry H , Haines John R , Govind Rakesh 
Published: March 2010

Abstract
Acid mine drainage from abandoned mines and acid mine pit lakes is an important environmental concern and usually contains appreciable concentrations of heavy metals. Because sulfate-reducing bacteria (SRB) are involved in the treatment of acid mine drainage, knowledge of acute metal toxicity levels for SRB is essential for the proper functioning of the treatment system for acid mine drainage. Quantification of heavy metal toxicity to mixed cultures of SRB is complicated by the confounding effects of metal hydroxide and sulfide precipitation, biosorption, and complexation with the constituents of the reaction matrix. The objective of this paper was to demonstrate that measurements of dissolved metal concentrations could be used to determine the toxicity parameters for mixed cultures of sulfate-reducing bacteria. The effective concentration, 100% (EC100), the lowest initial dissolved metal concentrations at which no sulfate reduction is observed, and the effective concentration, 50% (EC50), the initial dissolved metal concentrations resulting in a 50% decrease in sulfate reduction, for copper and zinc were determined in the present study by means of nondestructive, rapid physical and chemical analytical techniques. The reaction medium used in the experiments was designed specifically (in terms of pH and chemical composition) to provide the nutrients necessary for the sulfidogenic activity of the SRB and to preclude chemical precipitation of the metals under investigation. The toxicity-mitigating effects of biosorption of dissolved metals were also quantified. Anaerobic Hungate tubes were set up (at least in triplicate) and monitored for sulfate-reduction activity. The onset of SRB activity was detected by the blackening of the reaction mixture because of formation of insoluble ferrous sulfide. The EC100 values were found to be 12 mg/L for copper and 20 mg/L for zinc. The dissolved metal concentration measurements were effective as the indicators of the effect of the heavy metals at concentrations below EC100. The 7-d EC50 values obtained from the difference between the dissolved metal concentrations for the control tubes (tubes not containing copper or zinc) and tubes containing metals were found to be 10.5 mg/L for copper and 16.5 mg/L for zinc. Measurements of the turbidity and pH, bacterial population estimations by means of a most-probable number technique, and metal recovery in the sulfide precipitate were found to have only a limited applicability in these determinations.
Effects of bisphenol A and tetrabromobisphenol A on sex organ development in quail and chicken embryos
Authors: Berg Cecilia , Halldin Krister , Brunström Björn 
Published: March 2010

Abstract
The plastic monomere bisphenol A (BPA) and the flame retardant tetrabromobisphenol A (TBBPA) were examined for estrogen-like developmental effects on the reproductive organs in avian embryos. The synthetic estrogen diethylstilbestrol (DES) was used as a positive control. The test compounds were injected into the yolk of quail and chicken eggs early during incubation and the embryos were examined 2 d before anticipated hatching. At 200 μg/g egg, BPA induced Müllerian duct (embryonic oviduct) malformation in female quail embryos and feminization of the left testis (ovotestis) in male chicken embryos. The estrogenic potency of BPA compared with DES was species and endpoint specific. Müllerian duct malformation was the most sensitive endpoint in quail embryos, whereas ovotestis formation was the most sensitive response in chicken embryos. Tetrabromobisphenol A caused high embryo mortality at 45 μg/g egg in both species, but no estrogen-like effects were observed. Bisphenol A caused mortality only in chicken embryos at 67 and 200 μg/g egg. To our knowledge, this is the first report on estrogen-like or embryolethal effects of BPA and TBBPA in birds.
Using a biology-based model (DEBtox) to analyze bioassays in ecotoxicology: Opportunities and recommendations
Authors: Péry Alexandre R. R. , Flammarion Patrick , Vollat Bernard , Bedaux Jacques J. M. , Kooijman Sebastiaan A. L. M. , Garric Jeanne 
Published: March 2010

Abstract
The conventional analysis of bioassays does not account for biological significance. However, mathematical models do exist that are realistic from a biological point of view and describe toxicokinetics and effects on test organisms of chemical compounds. Here we studied a biology-based model (DEBtox) that provides an estimate of a no-effect concentration, and we demonstrated the ability of such a model to adapt to different situations. We showed that the basic model can be extended to deal with problems usually faced during bioassays like time-varying concentrations or unsuitable choices of initial concentrations. To reach this goal, we report experimental data from Daphnia magna exposed to zinc. These data also showed the potential benefit of the model in understanding the influence of food on toxicity. We finally make some recommendations about the choice of initial concentrations, and we propose a test with a depuration period to check the relevance and the predictive capacity of the DEBtox model. In our experiments, the model performed well and proved its usefulness as a tool in risk assessment.
Photodechlorination of 3,3′-dichlorobenzidine in water
Authors: Nyman Marianne C. , Haber Ken S. , Kenttämaa Hilkka I. , Iii Ernest R. Blatchley 
Published: March 2010

Abstract
Laboratory experiments have been conducted to elucidate the photochemical behavior of 3,3′-dichlorobenzidine (DCB) and its congeners in aquatic systems. Photodechlorination of DCB was observed in aqueous samples that were irradiated with monochromatic radiation from a variable-wavelength laser at several wavelengths in the range 300 nm ≤ λ ≤ 360 nm. Analytical measurements performed by high-performance liquid chromatography (HPLC) and Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry revealed that 3-chlorobenzidine (MCB) was produced as a transient intermediate in the photodechlorination process, with subsequent photodechlorination to yield benzidine as a stable photoproduct. Data obtained from these measurements also suggest the existence of other (unidentified) reaction pathways and products. The time-course measurements of chlorobenzidine congener concentrations and irradiance history were combined with a simple reaction model to develop estimates of reaction kinetics. Model predictions were consistent with results obtained for all wavelengths investigated.
Antifungal activity of some trityl-based synthetic dyes
Authors: Oros Gyula , Cserhati Tibor , Forgacs Esther 
Published: March 2010

Abstract
The fungicidal activity of 10 trityl dyes and six reference compounds was determined on 36 fungal strains, and the data matrix was evaluated separately by principal component analysis (PCA) and by spectral mapping technique (SPM). The dimensionality of the maps of the principle component loadings and variables and the selectivity maps were reduced to two by varimax rotation and by nonlinear mapping. Calculations proved that both the strength and selectivity of the fungicidal activity of trityl dyes considerably depended on the chemical structure of the dye and on the type of fungi. Both PCA and SPM were suitable for evaluation of the antifungal activity of dyes; however, the strength and selectivity of the fungicidal effect can be separated only by SPM. Due to its advantageous application parameters, use of SPM in future quantitative structure-activity relationship studies is highly recommended.
Biological properties of arginine-based gemini cationic surfactants
Authors: Pérez Lourdes , Garcia Maria Teresa , Ribosa Isabel , Vinardell Maria Pilar , Manresa Angeles , Infante Maria Rosa 
Published: March 2010

Abstract
Biological properties of novel gemini (double-chain/double-head) cationic surfactants, Nα,Nω-bis(Nα-acylarginine)α,ω-alkylendiamides, so-called bis(Args), are reported. The effect of both the alkyl (10 and 12 carbon atoms) and the spacer chain (from 2–10 methylene groups) of bis(Args) on their antimicrobial activity, acute toxicity on Daphnia magna and Photobacterium phosphoreum, and aerobic biodegradability is studied. These surfactants constitute a novel class of chemicals of low toxicity with excellent surface properties and considerable antimicrobial activity. The aquatic toxicity of these compounds is lower than that of the conventional Monoquats. As regards the biodegradation test, the molecules with a spacer chain ⩽6 methylene groups can be considered as ready biodegradable. The increase of hydrophobicity in the bis(Args) is a negative structural parameter for their environmental behavior.
Reproductive characteristics of male mosquitofish (Gambusia affinis) inhabiting a small southeastern U.S. river receiving treated domestic sewage effluent
Authors: Angus Robert A. , Weaver Season A. , Grizzle John M. , Watson R. Douglas 
Published: March 2010

Abstract
A population of western mosquitofish (Gambusia affinis) living below a wastewater treatment plant in the vicinity of Birmingham (AL, USA) was studied for evidence of exposure to estrogens. Mosquitofish are sexually dimorphic live-bearing fish. Males have an elongated and modified anal fin, called a gonopodium, used in mating. It has been hypothesized that exposure to estrogens and/or anti-androgens in treated wastewater might inhibit the androgen-dependent development of the gonopodium. The population in this study showed no evidence of having been exposed to endocrine-disrupting chemicals. The difference in adjusted (for overall fish size via analysis of covariance) mean gonopodium length between effluent-exposed and control populations was not significant. No detectable levels of vitellogenin were observed in the blood of any of the male mosquitofish, either from the effluent-exposed or the control population. Testes and livers were weighed and examined histologically. The fish exposed to treated wastewater effluent had significantly larger adjusted mean weights for both testis and liver, but no histological changes indicating exposure to estrogens were observed.
Better bootstrap estimation of hazardous concentration thresholds for aquatic assemblages
Authors: Grist Eric P. M. , Leung Kenneth M. Y. , Wheeler James R. , Crane Mark 
Published: March 2010

Abstract
The introduction of species sensitivity distribution (SSD) approaches to ecological risk assessment offers the potential for a more transparent scientific basis for the derivation of predicted no-effect concentrations. However, conventional SSD methodologies have relied on standard distributions (e.g., log logistic, log normal) that are not necessarily based on sound ecological or statistical grounds. More recently, bootstrap resampling techniques that do not rely on distributional assumptions have been applied to the problem. Here we describe how a more advanced bootstrap methodology may be applied to derive better point estimates and confidence intervals for SSD estimates of safe environmental concentrations. Motivated by the fact that the true SSD may not fit any standard model category, we go on to consider a hybrid bootstrap regression approach. This can yield a substantially different estimate for the SSD when compared with both the basic bootstrap and the more frequently used parametric curve approaches. With increasing use of SSDs in ecological risk assessment, it is now imperative that the scientific community develops agreement over appropriate methods for their derivation.
Loss of capacity to elevate plasma cortisol in rainbow trout (Oncorhynchus mykiss) treated with a single injection of o,p′-dichlorodiphenyldichloroethane
Authors: Benguira Sandrine , Leblond Vincent S. , Weber Jean-Philippe , Hontela Alice 
Published: March 2010

Abstract
The organochlorine o,p′- dichlorodiphenyldichloroethane (o,p′-DDD) is a metabolite of dichlorodiphenyltrichloroethane (DDT), known for its adrenolytic actions in birds and mammals. The effects of o,p′-DDD on the cortisol stress response were investigated in rainbow trout, Oncorhynchus mykiss, in a dose-response study in vivo. A dose-dependent decrease in plasma cortisol levels was observed on days 7 and 14 after a single i.p. injection of o,p′-DDD. Treatment with o,p′-DDD had no effect on weight gain, hematocrit, and gonado- or hepatosomatic index but decreased liver glycogen reserves. The results indicate that o,p′-DDD is an adrenotoxic compound in rainbow trout and that its effects can be detected even 14 d postinjection.
Sponge halogenated natural products found at parts-per-million levels in marine mammals
Authors: Vetter Walter , Stoll Elke , Garson Mary J. , Fahey Shireen J. , Gaus Caroline , Müller Jochen F. 
Published: March 2010

Abstract
Several unknown, abundant brominated compounds (BCs) were recently detected in the blubber of dolphins and other marine mammals from Queensland (northeast Australia). The BCs were interpreted as potential natural products due to the lack of anthropogenic sources for these compounds. This study investigated whether some of the BCs accumulated by diverse marine mammal species are identical with natural BCs previously isolated from sponges (Dysidea sp.) living in the same habitat. Isolates from sponges and mollusks (Asteronotus cespitosus) were compared with the signals detected in the mammals' tissue. Mass spectra and gas chromatography retention times on four different capillary columns of the isolates from sponges and mammals were identical in all respects. This proves that the chemical name of the compound previously labeled BC-2 is 4,6-dibromo-2-(2′,4′-dibromo)phenoxyanisole and that the chemical name of BC-11 is 3,5-dibromo-2-(3′,5′-dibromo,2′-methoxy)phenoxyanisole. Using a quantitative reference solution of BC-2, we established that the concentrations of the brominated metabolites found in the marine mammals are frequently &gt;1 mg/kg. The highest concentration (3.8 mg/kg), found in a sample of pygmy sperm whale (Kogia breviceps), indicates that BC-2 is a bioaccumulative, natural organohalogen compound. This is supported by the concentrations of the BCs in our samples being equal to the highest concentrations of anthropogenic BCs in any environmental sample. The quantitative determination of BC-2 in blubber of marine mammals from Africa and the Antarctic suggests that BC-2 is widespread. These results are direct proof that marine biota can produce persistent organic chemicals that accumulate to substantial concentrations in higher trophic organisms.
Level and extent of mercury contamination in Oregon, USA, lotic fish
Authors: Peterson Spencer A. , Herlihy Alan T. , Hughes Robert M. , Motter Kathryn L. , Robbins James M. 
Published: March 2010

Abstract
We conducted a probability survey of 154 Oregon, USA, stream and river sites to assess the spatial extent of mercury (Hg) contamination in fish tissue. Samples consisted of whole-fish analyses of both small (&lt;120 mm) and large (&gt;120 mm) fish at each site, when both were present. Overall, Hg levels (μg/g in small fish (X = 0.031; standard deviation [SD] = 0.029), large piscivores (X = 0.284; SD = 0.175), and large invertivores (X = 0.055; SD = 0.047) were found within fairly narrow ranges; always above detection (0.0025 μg/g) and almost always below 0.4 μg/g. Given the great ecoregion diversity across Oregon, the narrow range in fish tissue Hg levels suggests that atmospheric transport is an important vehicle for Hg distribution. In small fish, Hg levels were almost always low and showed little meaningful difference among fish taxa. In large fish, Hg levels were significantly related to fish length. Piscivores (pikeminnow and bass) had significantly higher Hg levels, and the slope of their Hg level/length relationship was much steeper than for invertivores. Salmonids, the most commonly occurring fish taxon in Oregon, exceeded 0.1 μg Hg/g (deemed protective for fish-eating mammals) in an inferred 15% of stream lengths where they occurred. Pikeminnows and bass were found at fewer sites, but they exceeded 0.1 μg Hg/g in an inferred 96 and 70%, respectively, of stream lengths where they occurred.
Dichlorodiphenyltrichloroethane in the aquatic ecosystem of the Okavango Delta, Botswana, South Africa
Authors: Mbongwe Bontle , Legrand Melissa , Blais Jules M. , Kimpe Lynda E. , Ridal J. Jeffrey , Lean David R. S. 
Published: March 2010

Abstract
Concentrations of DDT and its metabolites were measured in water, plants, invertebrates, and fish from lagoons in the Okavango Delta, Botswana (Africa), where DDT has been used for approximately 50 years. The sampling area was sectioned to distinguish spraying for malaria and for African sleeping sickness. Average concentrations of total DDT (sum of DDT and its metabolites) in the Okavango ranged from 0.009 ng/L in water to 18.76 ng/g wet weight in fish. These levels are approximately 1% of those found in piscivorous fish from temperate North America. The dichlorodiphenyl ethylene (DDE) metabolite was the most abundant fraction of total DDT. Although total DDT concentrations were higher in areas treated for malaria than areas treated for sleeping sickness, these concentrations were likely driven by factors other than the historic application of the pesticide. Equilibration with air concentrations is the most likely explanation for these levels. Since the mean annual temperature exceeds the temperature of vaporization of DDT, this research points to the need for reliable transport models. Our results showed that total DDT concentration in fish was best explained by lipid content of the fish and trophic position inferred by δ15N, regardless of DDT application history in those areas. The reservoir above Gaborone Dam, an area downstream of the Okavango but where DDT had not been used, was sampled to compare total DDT levels to the treated areas. The two species (a herbivorous threespot talapia and the omnivorous sharptooth catfish) from Gaborone had levels higher than those found in the Okavango Delta, but these differences can again be explained using trophic position inferred by δ15N rather than by fish size or location.
Selected resin acids in effluent and receiving waters derived from a bleached and unbleached kraft pulp and paper mill
Authors: Quinn Brian P. , Booth Matthew M. , Delfino Joseph J. , Holm Stewart E. , Gross Timothy S. 
Published: March 2010

Abstract
Water samples were collected on three dates at 24 sites influenced by effluent from Georgia-Pacific's Palatka Pulp and Paper Mill Operation, a bleached and unbleached kraft mill near Palatka, Florida, USA. The sampling sites were located within the mill retention ponds, Rice Creek, and the St. John's River. Samples were analyzed by gas chromatography-mass spectrometry for abietic, dehydroabietic, and isopimaric acids, all of which are potentially toxic by-products of pulp production. Isopimaric acid concentrations greater than 12 mg/L were measured at the mill's effluent outfall but were less than 20 μg/L at the end of Rice Creek. This result indicates that the waters of Rice Creek provide dilution or conditions conducive for degradation or sorption of these compounds. Large differences in resin acid concentrations were observed between sampling events. In two sampling events, the maximum observed concentrations were less than 2 mg/L for each analyte. In a third sampling event, all of the compounds were detected at concentrations greater than 10 mg/L. Data from the three sample dates showed that resin acid concentrations were below 20 μg/L before the confluence of Rice Creek and the St. John's River in all cases.