bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of microbial phenanthrene mineralization in sediment samples by sorbent-sorbate contact time, inocula and gamma irradiation-induced sterilization artifacts
Authors: Sandoli Robert L. , Ghiorse William C. , Madsen Eugene L. 
Published: March 2010

Abstract
Time-dependent diffusion and/or sorption reactions were proposed as a mechanism for protecting polycyclic aromatic hydrocarbons (PAHs) in surface and subsurface sediments from a coal tar waste-contaminated field site. 14C-labeled phenanthrene was aged in both subsurface sand and organic matter-rich seep sediments that had previously been sterilized by gamma irradiation. After aging periods ranging from 0 to 28 d, the sediments were dispensed to replicate vials and inoculated with site-derived phenanthrene-degrading microorganisms (with and without previous enrichment on phenanthrene), and cumulative 14CO2 production was measured. When pure culture and mixed inocula originated from the seep sediments, phenanthrene mineralization from sand sediment samples was retarded with longer aging periods. However, when a mixed inoculum originating from the sand sediments was tested, aging of the phenanthrene had only a slight or no effect on its rate or extent of mineralization. Thus, the susceptibility of phenanthrene to biodegradation varied with the source of the microbial inocula. When gamma-irradiated seep sediments were the sorbent, all mineralization of 14C phenanthrene was eliminated. Several hypotheses were tested for explaining this sorbent-dependent inhibition of phenanthrene metabolism. Gamma radiation-induced changes in the sorptive properties of the seep sediment seemed to be the cause.
Quantitative structure-activity relationships for polychlorinated hydroxybiphenyl estrogen receptor binding affinity: An Assessment of conformer flexibility
Authors: Bradbury Steven P. , Ankley Gerald T. , Mekenyan Ovanes G. 
Published: March 2010

AbstractA diverse group of xenobiotics has a high binding affinity to the estrogen receptor (ER), suggesting that it can accommodate large variability in ligand structure. Relationships between xenobiotic structure, binding affinity, and estrogenic response have been suggested to be dependent on the conformational structures of the ligands. To explore the influence of conformational flexibility on ER binding affinity, a quantitative structure—activity relationship (QSAR) study was undertaken with estradiol, diethylstilbestrol, and a set of polychlorinated hydroxybiphenyls (PCHBs) of environmental concern. Although the low-energy minima of the PCHB congeners suggested that interconversions among conformers were likely, the electronic parameters associated with the conformer geometries for a specific PCHB congener could vary significantly. The results of the QSAR analysis suggested that among the PCHBs studied, the most polarizable conformers (lower absolute volume polarizability values) were most closely associated with ER binding affinity. Across the set of “polarizable” conformers, which did not include the low-energy gas-phase conformers, the electron donating properties of the hydroxy moiety and the aromatic component of the estradiol A ring analogue in the PCHBs were found to be correlated with higher ER binding affinity.
The body ion loss biomarker. 1. Interactions between trace metals and low pH in reconstituted coal mine-polluted water
Authors: Grippo Richard S. , Dunson William A. 
Published: March 2010

Abstract
Net body ion loss of brook charr (Salvelinus fontinalis) was evaluated as a biomarker of the potential toxicity of coal mine-polluted water. Fish were exposed in reconstituted coal mine-polluted water prepared in a continuously flowing system with a mixture of 16 water chemistry variables adjusted to match stream concentrations measured in moderately and severely mine-impacted streams. Changes in net body cation (Na+, K+, and Ca2+) loss rates from the fish were determined. Metal/pH interactions were tested by exposing fish to (1) a mixture of all six potentially toxic metals (Al, Fe, Zn, Mn, Ni, and Cd or Pb), (2) individual metals, (3) no metals (low pH effect), or (4) time control. At severe levels (pH ≈ 3.34) all metal treatments caused a net whole-body sodium loss rate similar to that observed for pH alone. Body potassium rates were essentially unchanged from that of the control; a significant calcium influx observed under control conditions was eliminated by most acid and metal exposures. At less severe pollution levels (pH ≈ 3.95) some metals (Ni2+, Mn2+, and Zn2+) blocked the net loss of body sodium induced by acidity. We conclude that net body sodium loss rate is a sensitive, reproducible, and acute indicator of acid and trace metal pollution and may be a useful biomarker for determining the presence and degree of impact of coal mine-polluted water on fish.
A survey of estrogenic activity in United Kingdom inland waters
Authors: Harries Jule E. , Sheahan David A. , Matthiessen Peter , Neall Paula , Rycroft Richard , Tylor Tina , Jobling Susan , Routledge Edwin J. , Sumpter John P. 
Published: March 2010

Abstract
Vitellogenin, a yolk-precursor protein normally found only in the blood plasma of sexually mature female teleosts and other egg-laying vertebrates, was used as an indicator of exposure of male rainbow trout (Oncorhynchus mykiss) to exogenous estrogens. Vitellogenin concentrations were measured using a specific radioimmunoassay for trout. Cages containing adult male trout were placed at the points of discharge and at varying distances downstream of treated sewage effluent outfalls into the River Lea (UK) during the summer and winter months of 1992. After 3 weeks exposure at the majority of sites, fish held up to 15 km downstream of inputs showed an increase in plasma vitellogenin concentration, with statistically significant elevations up to 4.5 km downstream. A repeat survey in November 1992 below Harpenden sewage treatment works showed that the only two stations to give a significant response were 3 m and 1.6 km downstream of the outfall. This reduced effect compared to the first survey is thought to be due to dilution of both the influent sewage to the treatment works and of the river water itself by increased rainfall, the overall increase in dilution being approx. 36%. Trout were also placed in 15 raw water storage reservoirs in southeast England during the summer of 1993 for an exposure period of 6 weeks. No biologically significant increases in plasma vitellogenin concentration were observed in any of the reservoirs.
Property-toxicity relationships of azaarenes to the green alga Scenedesmus acuminatus
Authors: Van Vlaardingen Peter L. A. , Steinhoff Wilco J. , Admiraal Wim A. , De Voogt Pim 
Published: March 2010

Abstract
The toxicity of three two-ring and five three-ring azaarenes to the green alga Scenedesmus acuminatus and its relationship with molecular structure was investigated. Indole, quinoline, isoquinoline, and carbazole did not inhibit the growth rate of S. acuminatus in 96-h batch culture assays up to 10 mg/L. Chlorophyll-α content appeared to be a more sensitive response parameter than growth for five of six compounds. This parameter showed a relationship with hydrophobicity-related molecular descriptors like molecular surface area. Four benzoquinoline isomers showed notably different effects on growth rate and chlorophyll-α content. Median effect concentration (EC50) values obtained for growth rate were acridine, 0.32 mg/L; benzo[f]quinoline, 1.55 mg/L; phenanthridine, 5.24 mg/L; and benzo[h]quinoline, 6.65 mg/L. Similar differences existed in their EC50 values for chlorophyll-α content. The differences in toxicity between these isomers correlates with two electronical molecular descriptors, viz. the ionization potential and the homo—lumo gap. Several modes of action are put forward and their relative importance discussed.
Accumulation and biotransformation of tri-N-butyltin by isolated rainbow trout hepatocytes
Authors: Reader Stephanie , Louis Richard Saint , Pelletier ÉMilien , Denizeau Francine 
Published: March 2010

Abstract
In the present study, metabolism of tributyltin (TBT) by isolated trout hepatocytes was investigated over a short exposure time. For this, the cells were exposed to TBT, and the determination of TBT and possible metabolites was performed. Cell viability and cytochrome P-450 activity were also measured. After 15 min of exposure to 1 μM TBT, 72 ± 23% of the total tin recovery was observed in the cellular fraction, and about 3 and 4% of the total amount of tin was recovered as dibutyltin (DBT) in the cells and incubation medium, respectively. The amount of DBT leveled off after 15 min, probably because of the inhibition of cytochrome P-450. Thus, TBT is metabolized by fish hepatocytes. However, as it also inhibits cytochrome P-450 activity, it has the potential to alter its own metabolism and that of other environmental pollutants.
Predicting chronic toxicity of sediments spiked with zinc: An evaluation of the acid-volatile sulfide model using a life-cycle test with the midgeChironomus tentans
Authors: Sibley Paul K. , Ankley Gerald T. , Cotter Anne M. , Leonard Edward N. 
Published: March 2010

AbstractThe development of sediment quality criteria for the cationic metals cadmium, copper, lead, nickel, and zinc has focused on the use of acid-volatile sulfide (AVS) as the primary normalization phase for predicting interstitial pore-water concentrations and bioavailability of the metals. To date, most of the research in support of AVS in this context has utilized short-term laboratory exposures, with a relative paucity of information pertaining to long-term exposures. The purpose of this study, therefore, was to investigate the use of AVS as a predictor of metal toxicity to a benthic organism in a long-term laboratory exposure. Clean sediment was spiked with zinc to obtain nominal treatments ranging from −2.34 to 58.5 μg/g dry weight with respect to the molar difference between simultaneously extracted metal (SEM) and AVS. The test was initiated with newly hatched larvae of the midge Chironomus tentans and carried through one complete generation (56 d) during which survival, growth, emergence, and reproduction were monitored. When the molar difference between SEM and AVS (i.e., SEM – AVS) was &lt;0, the concentration of zinc in the sediment interstitial water was low and no adverse effects were observed for any of the biological endpoints measured. Conversely, when SEM – AVS exceeded 0, a dose-dependent increase in the relative concentration of zinc in the pore water was detected. However, the absolute concentration of pore-water zinc at each treatment declined over the course of the study, corresponding to an increase in sediment AVS and to a loss of zinc due to diffusion into the overlying water, which was renewed twice daily. Only when SEM – AVS exceeded 0 were significant reductions in survival, growth, emergence, and reproduction observed. Together, the chemical and biological data from this study compare favorably with observations made in short-term exposures and thus support the use of AVS as a normalization phase for predicting toxicity in metal-contaminated sediments.
Chronic effect of cadmium in sediments on colonization by benthic marine organisms: An evaluation of the role of interstitial cadmium and acid-volatile sulfide in biological availability
Authors: Hansen David J. , Mahony John D. , Berry Walter J. , Benyi Sandra J. , Corbin Jeffrey M. , Pratt Sheldon D. , Di Toro Dominic M. , Abel Mary Beth 
Published: March 2010

Abstract
The role of interstitial cadmium and acid-volatile sulfide (AVS) in controlling the bioavailability of sediment-associated metal was examined using the chronic saltwater benthic colonization test. Sediments were spiked to achieve nominal cadmium/ AVS molar ratios of 0.0 (control), 0.1, 0.8, and 3.0 in this 118-d test. Oxidation of AVS in the surficial 2.4 cm within 2 to 4 weeks resulted in sulfide profiles similar to those occurring naturally in local sediments. In the nominal 0.1 cadmium/AVS treatment, measured simultaneously extracted metal (SEMcd) was always less than AVS. Interstitial cadmium concentrations (&lt;3-10 μg/L) were less than those likely to cause biological effects. No significant biological effects were detected. In the nominal 0.8 cadmium/ AVS treatment, measured SEMcd commonly exceeded AVS in the surficial 2.4 cm of sediment. Interstitial cadmium concentrations (24-157 μg/L) were of likely toxicological significance to highly sensitive species. Shifts in the presence or absence over all taxa, and fewer macrobenthic polychaetes (Mediomastus ambiseta, Streblospio benedicti, and Podarke obscurd) and unidentified meio-faunal nematodes, were observed. In the nominal 3.0 cadmium/AVS treatment, concentrations of SEMcd were always greater than AVS throughout the sediment column. Interstitial cadmium ranged from 28,000 to 174,000 μg/L. In addition to the effects above, these sediments were colonized by fewer macrobenthic species, polychaete species, and harpacticoids; had lower densities of diatoms; lacked bivalve molluscs; and exhibited other impacts. Over all treatments, the observed biological responses were consistent with SEMcd/AVS ratios in surficial sediments and interstitial water cadmium concentrations.
Effect of bioturbation on metal-sulfide oxidation in surficial freshwater sediments
Authors: Peterson Gregory S. , Ankley Gerald T. , Leonard Edward N. 
Published: March 2010

AbstractRecent studies have demonstrated the role of acid-volatile sulfide (AVS) in controlling the bioavailability of several cationic metals in anoxic sediments. However, metal-sulfide complexes can be relatively labile with respect to oxidation associated with factors such as seasonal changes in rates of oxidation/production of AVS. Another potentially important mechanism of AVS oxidation in surficial sediments is bioturbation. We used different densities of the burrowing oligochaete Lumbriculus variegatus in a series of laboratory experiments to evaluate the effect of bioturbation on oxidation of AVS and subsequent bioavailability of cadmium and zinc spiked into freshwater sediments. Metal bioavailability was determined directly by bioaccumulation in the test organisms and indirectly through analysis of interstitial (pore) water metal concentrations. In our studies, horizon-specific sediment analyses were conducted to assess spatial differences in AVS and pore-water metal concentrations specifically related to organism activity. Burrowing activity of the oligochaete significantly reduced AVS concentrations in surficial sediments in a density-dependent manner and resulted in elevated interstitial water concentrations of cadmium but not zinc. Concentrations of cadmium in pore water from deeper horizons (below the zone of active burrowing) were consistently lower than those in the surficial sediments. The bioaccumulation of cadmium and zinc by L. variegatus was reflective of pore-water concentrations of the two metals, i.e., there was significant accumulation of cadmium, but not zinc, by the oligochaetes. Overall, our results indicate that bioturbation can enhance the bioavailability of some cationic metals in surficial sediments, via oxidation of AVS, and demonstrate the importance of analyzing surficial sediments when assessing bioavailability of metals in sediments.
Particle oxidation model of synthetic FeS and sediment acid-volatile sulfide
Authors: Di Toro Dominic M. , Mahony John D. , Gonzalez Adrian M. 
Published: March 2010

AbstractA model is proposed for the kinetics of the oxidation of acid-volatile sulfide (AVS). It is based on a surface oxidation reaction that erodes the particle surface until the particle disappears. A monodisperse particle size distribution is assumed with a reaction rate that is proportional to the surface area remaining and a dimensional exponent that relates the surface area to the particle volume. The model is fit to time course data from a number of experiments conducted using synthetic FeS at various pHs, oxygen concentrations, and ionic strengths. The reaction rate constants are modeled using a surface complexation model. It is based upon the formation of two activated surface complexes with molecular oxygen, one of which is charged. The complexation model provides a good fit to the variation of the reaction rate constant with respect to O2, pH, temperature, and ionic strength. The dimensional exponent v increases with pH from values characteristic of plates and needles to values reflecting more spherical particles, presumably due to coagulation. However the increase in v with respect to O2 at high concentrations is unexplained.
A laboratory-formulated sediment incorporating synthetic acid-volatile sulfide
Authors: Gonzalez Adrian M. 
Published: March 2010

AbstractThe application of laboratory-formulated sediment (LFS) could be expanded if toxicologically significant characteristics of sediment other than particle-size distribution, organic carbon content, and pH could be manipulated. This report describes the preparation of a LFS containing synthetic acid-volatile sulfide (AVS) and shows its similarity to natural sediment AVS. Several formulations were evaluated with respect to toxicity to Hyalella azteca and chemical stability. Amphipod survival was highest (95%) in LFS formulations in which the molar iron(II)/sulfide ratio was near 1, although amphipod survival was &gt;l80% in six of seven formulations with ≤20% excess metal or sulfide. Synthetic AVS in the test system oxidized rapidly at the sediment surface, but AVS at depth was stable for &gt;30 d when isolated from air or aerated water. Oxidation-reduction potential measurements and AVS analysis of core slices revealed a vertical oxidation profile, apparently established and limited by oxygen diffusion. A formulation consisting of a 1:1 molar ratio of iron and sulfide (FeS) was evaluated with respect to complexation of copper, zinc, and nickel and to the corresponding reduction in toxicity using W-AH. azteca toxicity tests. Amphipod mortality in metal-spiked LFS with metal/AVS molar ratios &gt;1 was high relative to controls. In contrast, amphipod survival in metal-spiked LFS with metal/AVS molar ratios &gt;1 was generally similar to amphipod survival in nonspiked LFS containing synthetic AVS. A few exceptions, where toxicity was noted when metal/AVS ratios were &lt;1, could be explained by high concentrations of dissolved iron, which was released by the metal + AVS displacement reaction. The LFS containing synthetic AVS appears to mimic natural sediment AVS and thus can provide consistent and controlled substrates suitable for investigating metal/sediment chemistry and toxicity and for developing realistic sediment quality criteria for metals.
Choosing a cosolvent: Solubilization of naphthalene and cosolvent property
Authors: Li An , Yalkowsky Samuel H. , Andren Anders W. 
Published: March 2010

Abstract
The addition of an organic cosolvent to water can increase the aqueous solubility of many hydrophobic organic compounds (HOCs). This work examines the correlations between the change of naphthalene solubility and various physicochemical properties of the cosolvent added to the system. Results show that the dielectric constant and surface tension do not correlate with the solubilization power of cosolvent toward naphthalene. The solubility parameter correlates well with increases in naphthalene solubility and therefore provides a convenient tool when screening cosolvents for their ability to enhance HOC solubility in various environmental engineering applications. Other properties investigated include the octanol/water partition coefficient, interfacial tension, ET(30), viscosity, and hydrogen bonding capacities.
The effect of enzyme treatment on untreated d-stage effluent: Short-term fish early life-stage toxicity test
Authors: Jacobsen Frank , Folke Jens 
Published: March 2010

Abstract
Short-term early-life-stage toxicity experiments were conducted using zebra fish (Brachydanio rerio) under semistatic conditions. The test parameters studied were percent hatching success, median time from fertilization to hatching, median survival of embryos and larvae, frequency of abnormal larvae, as well as larval growth. Test organisms were exposed to a sample of raw spent bleach liquor from the D-stage of a softwood bleached-kraft pulp mill and the sample after treatment with a peroxidase enzyme, which resulted in a 50% decrease in residual phenolic components (0.123 vs. 0.061mg/L). In the untreated D-stage sample, the median survival of embryos and larvae was calculated to be 151 ml/L; the lowest-observed-effect concentration was 50 ml/L, and the no-observed-effect concentration was 25ml/L. No dose response could be established for fish exposed to peroxidase-treated D-stage liquor; the treated effluent was only minimally toxic in this short-term test.
C-18-coated silica particles as a surrogate for benthic uptake of hydrophobic compounds from bedded sediment
Authors: Lake James L. , Osterman Frank A. , McKinney Richard , Lake Carol A. 
Published: March 2010

Abstract
To simulate the bioaccumulation of neutral organic contaminants by infaunal benthos, the partitioning of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) between a contaminated estuarine sediment and admixed C-18-coated silica particles was measured. The concentrations of lower chlorinated PCB congeners (less than five chlorine atoms per molecule) on the C-18-coated silica particles reached apparent steady state within 300 h while congeners with greater numbers of chlorine atoms required much greater time periods (greater than 1 year) to reach apparent steady state. Polycyclic aromatic hydrocarbons showed less partitioning from sediment to the C-18 particles than PCB congeners, although the log Kow ranges of the compounds in these comparisons were similar. The biota sediment accumulation factors, defined as the lipid-normalized contaminant concentration in an exposed organism divided by the organic carbon-normalized contaminant concentration of the sediment, were calculated for these exposures using the C-18 of the particles as the lipid. The results from these exposures agreed closely with those measured in studies where living benthic organisms were exposed to contaminated sediment.
Biodegradation of thiophene, benzothiophene, and benzofuran with eight different primary substrates
Authors: Dyreborg Søren , Arvin Erik , Broholm Kim , Christensen Jens 
Published: March 2010

Abstract
The aerobic biodegradation of thiophene, benzothiophene, and benzofuran was studied in microcosm experiments using groundwater microorganisms as inoculum. Benzofuran, a heterocyclic aromatic compound containing oxygen, was biodegraded as a sole source of carbon and energy measured by the disappearance of the compound, whereas two heterocyclic aromatic compounds containing sulphur (thiophene and benzothiophene) were not used as growth substrates. Thiophene was biodegraded with benzene, toluene, and to some extent ethylbenzene as primary substrates. Some biodegradation of thiophene was observed when p-xylene, o-xylene, m-xylene, naphthalene, and 1-methylnaphthalene were the primary substrates. Benzothiophene was completely transformed, with all eight primary substrates investigated except for benzene and p-xylene, in which 34 and 6% of benzothiophene, respectively, remained after 40 d of incubation. Although benzofuran could be used as a sole source of carbon and energy, data showed that the biodegradation of benzofuran definitely was enhanced by the biodegradation of the primary substrates used.