bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunomodulation by heavy metals tested individually or in mixtures in rainbow trout (Oncorhynchus mykiss) exposed in vivo
Authors: Sanchez-Dardon Jaime , Voccia Isabelle , Hontela Alice , Chilmonczyk Stefan , Dunier Muriel , Boermans Herman , Blakley Barry , Fournier Michel 
Published: March 2010

Abstract
The objective of this study was to evaluate the effect of heavy metals, at environmentally relevant concentrations, on the immune response of rainbow trout. Trout were exposed for 30 d to cadmium chloride (CdCl2), mercuric chloride (HgCl2), or zinc chloride (ZnCl2) either individually or in combinations: CdCl2/HgCl2, CdCl2/ZnCl2, HgCl2/ZnCl2, or CdCl2/HgCl2/ZnCl2. Following the 30-d exposure, parameters of the nonspecific cellular immune response (phagocytosis, respiratory burst, and lymphoblastic proliferation) and of the nonspecific humoral immune response (lysozyme activity and the level of immunoglobulin) were measured. The results obtained indicate that individually, all three metals tested induce significant immunomodulations. However, the toxicity of mercury or cadmium is significantly reduced in fish simultaneously exposed to zinc, indicating that a protection is afforded by zinc against cadmium- and mercury-induced immunotoxicity.
Occurrence of retene and resin acids in sediments and fish bile from a lake receiving pulp and paper mill effluents
Authors: Leppänen Harri , Oikari Aimo 
Published: March 2010

AbstractRetene (7-isopropyl−1-methylphenanthrene) is a dialkyl-substituted PAH derived thermally and microbially from dehydroabietic acid. We have analyzed for retene and several resin acids in sediments at five depths at several sites in a lake receiving effluents from three pulp and paper mills, and two upstream reference sites. The highest concentration of retene was 1,600 μg/g dry weight (11,700 μg/g organic carbon [OC]) and of total resin acids was 1,500 μg/g dry weight (9,300 μg/g OC). Twelve kilometers downstream from the point of bleached-kraft mill effluent (BKME) discharge, the concentration of retene at a depth of 5 to 10 cm was 16 μg/g dry weight (650 μg/g OC) and of resin acids was 139 μg/g dry weight (1,700 μg/g OC). Upstream of the BKME discharge, the concentration of retene was below 0.1 μg/g dry weight and of resin acids was below 70 μg/g dry weight. To assess the bioavailability of retene to fish we determined its concentration in the bile of roach (Rutilus rutilus) and perch (Perca fluviatilis) caught 1 to 2 km downstream of pulp and paper mills and in the reference area. Retene was bioavailable to roach, which primarily feed on benthic organisms; however, retene was not detected in perch bile.
High frequency of K-ras mutations in pink salmon embryos experimentally exposed to Exxon valdez oil
Authors: Roy Nirmal K , Stabile Joseph , Seeb James E , Habicht Christopher , Wirgin Isaac 
Published: March 2010

Abstract
Previous studies demonstrated reduced survivorship of pink salmon embryos from populations in Prince William Sound, Alaska, USA, that were exposed to Exxon Valdez–released oil compared with populations from matched nonoiled streams. Survivorship was also significantly decreased in embyros from lineages that were oiled in Prince William Sound and reared in clean water under controlled hatchery conditions compared with the descendants of nonoiled lineages. This suggests that the effect of oiling on pink salmon populations was persistent and could be transmitted intergenerationally. However, the ability of environmentally released oil to cause DNA sequence alterations in natural populations has yet to be demonstrated. We used polymerase chain reaction analysis to screen for alterations in the K-ras oncogene in DNA from pink salmon embryos that were exposed under controlled laboratory conditions to weathered Prudhoe Bay crude oil. Polymerase chain reaction and direct DNA sequence analyses were used to identify mutational hotspots within exons 1 and 2 of K-ras, and 3′ primer mismatch analysis was used to determine the frequency of mutations in the 40 offspring of two families of pink salmon that were experimentally exposed to oiled or clean gravel. Mutations were only observed at codons 12, 13, and 61 of K-ras, sites that are frequently mutated in animal and human tumors. All mutations resulted in deduced amino acid substitutions. As expected, in all individuals exhibiting mutations, the copy number of the normal allele exceeded that of the mutated allele. The frequencies of mutations in oiled embryos at K-ras exons 1 and 2 were 68 and 41%, respectively. K-ras mutations were not observed in siblings that were exposed to clean gravel or in the parents of the two experimental matings. These results indicate that exposure of pink salmon embryos to weathered Prudhoe Bay crude oil under controlled laboratory conditions can elicit somatic cell mutations in high frequency at mutational hotspots in genes such as K-ras. However, the frequency of these events in oiled natural populations of pink salmon and other vulnerable species in Prince William Sound and the heritability of these mutations within oiled lineages have yet to be evaluated.
Fully defined saltwater medium for cultivation of and toxicity testing with marine copepod Acartia tonsa
Authors: Kusk K Ole , Wollenberger Leah 
Published: March 2010

Abstract
The marine copepod Acartia tonsa and the food organism Rhodomonas salina were cultured in fully defined medium for 8 months without problems. Both organisms were also cultured in natural seawater and in a commercial salt mixture for at least two generations before the sensitivities of A. tonsa to bisphenol A, potassium dichromate, nonylphenol, and 3,5-dichlorophenol in the three different media were compared and found to be at the same level. The defined medium may be used for cultivation and testing, thus avoiding unknown background contaminants.
Low exposure concentrations of atrazine increase male production in Daphnia pulicaria
Authors: Dodson Stanley I , Merritt Christine M , Shannahan Jon-Paul , Shults Catherine M 
Published: March 2010

Abstract
Results of 24 bioassays with the water flea (Daphnia pulicaria) show an exposure–response relationship between Daphnia sex ratio and the herbicide atrazine. Exposure of Daphnia to atrazine during embryogenesis resulted in a shift in sex determination toward males. The shift was detectable at 0.5 ppb (nominal concentration) and pronounced at 10 ppb or more. The shift occurred in the upper part of the range of atrazine concentrations commonly found in aquatic environments (such as lakes, streams, wells, and rainwater). Our results suggest that Daphnia sex ratio is one to two orders of magnitude more sensitive to atrazine than are survivorship or fecundity.
Ecological risk assessment of agrochemicals in European estuaries
Authors: Steen Ruud J C A , Leonards Pim E G , Brinkman Udo A Th , Barceló Damia , Tronczynski Jacek , Albanis Triantafyllos A , Cofino Wim P 
Published: March 2010

Abstract
The Fluxes of Agrochemicals into the Marine Environment (FAME) project, which was funded by the European Union, studied the presence and fate of pesticides in major European river/estuary systems. As part of the cooperation within FAME, samples from four rivers were sent to all participants. Each laboratory analyzed the samples with a range of techniques, thus creating a database that could not have been developed through individual efforts. In the present study, compounds are identified that are important to the contamination of the marine environment on the basis of their environmental concentrations and toxicological properties. Two risk assessment methods are used. The toxic unit method, which provides a first indication of the relative contribution of compounds to the total toxicity of a sample, and the inverse method of Van Straalen and Denneman, which has been used to assess the ecological risk of a selected set of compounds (i.e., atrazine, simazine, alachlor, and metolachlor). Environmental concentrations of these target compounds were determined at different seasons during a period of at least 1 year and, hence, variations in ecological risk patterns for different European river/estuary systems could be identified. The application of the risk assessment procedures is hampered by a lack of toxicological data. It is concluded, however, that pesticides exert a significant pressure on the aquatic system. To our knowledge, this is the first joint study in which the ecological risks of modern pesticides related to different European river/estuary systems are compared.
Adsorption-desorption behaviors of hydrophobic organic compounds in sediments of Lake Charles, Louisiana, USA
Authors: Chen Wei , Kan Amy T , Fu Gongmin , Vignona Laine C , Tomson Mason B 
Published: March 2010

Abstract
Neutral organic contaminants commonly reside on the solid portion of soils and sediments. The extent of desorption from these solids determines the fate, reactivity, and toxicity. Numerous researchers have observed that, after an initial exposure of a few days, desorption takes place in two phases, namely, an initial rapid release followed by a long-term resistant phase. Resistant desorption has been highly unpredictable. In this research, the adsorption and desorption of chlorobenzenes, hexachlorobutadiene, and naphthalene have been studied using historically and freshly contaminated bayou sediments from Lake Charles, Louisiana, USA. After an initial release period, both laboratory-spiked and historically contaminated sediments exhibit similar desorption profiles. The simulations compare favorably with previous in situ measurements. All desorption results, both laboratory and field, could reasonably be interpreted using a single irreversible isotherm. Consequences of these results in terms of sediment quality criteria (SQC) are also discussed. Finally, an index of fractional irreversible adsorption is proposed and tested.
Interactions of dissolved organic matter with xenobiotic compounds: Molecular modeling in water
Authors: Schulten Hans-Rolf 
Published: March 2010

Abstract
An hypothesis for the structure of dissolved organic matter (DOM) in water is proposed. It is based on previously published humic acid and soil organic matter (SOM) models. Personal computer (PC)-based molecular modeling and geometry optimization of DOM and humic/xenobiotic complexes in vacuo and water were performed using modern PC software in order to determine low energy conformations and to simulate site-specific processes such as trapping and binding of biological and anthropogenic substances. Nanochemistry (10−9 m level) allows the evaluation of atomic and molecular space requirements, voids, inter- and intramolecular hydrogen bonds, and interactions with water, metal cations, and xenobiotics. The described modeling approach in general allows hydrophilic and hydrophobic reactions to be examined. Structural, molecular, and environmental properties of DOM and its xenobiotic complexes were determined by quantitative structure-activity relationship software. Focal points were molecular properties, such as solvent accessibility as well as van der Waals surface areas and volumes, partial charges, hydration energy (peptides), hydrophobicity (log P), refractivity, and polarizabilities of humic/xenobiotic complexes were determined. Molecular mechanics calculations show that nonbonded forces (e.g., van der Waals) and hydrogen bonds were the main reasons for temporary immobility of xenobiotic substances retained in DOM. Preliminary experiments to simulate the acidity of water molecules by protonation-enhanced reactions with polar xenobiotics (e.g., hydroxyatrazine) but left nonpolar substances (e.g., DDT) unchanged.
Molecular models of benzene and selected polycyclic aromatic hydrocarbons in the aqueous and adsorbed states
Authors: Kubicki James D , Blake Geoffrey A , Apitz Sabine E 
Published: March 2010

Abstract
Energy gaps between the highest-occupied molecular orbital and lowest-unoccupied molecular orbital (ΔEHOMO-LUMO) for a suite of common polycyclic aromatic hydrocarbons (PAHs) in the gas-phase were calculated with three different molecular modeling methods: semiempirical, ab initio Hartree-Fock, and density functional calculations. Results indicate that semiempirical, Hartree-Fock, and density functional calculations may provide useful relative HOMO-LUMO gap information, but these methods overestimate the actual ΔEHOMO-LUMO. Based on vibrational frequency analyses, density functional calculations reliably produce dynamically stable structures that can be used to predict model ΔEHOMO-LUMO values. Both the semiempirical and ab initio Hartree-Fock methods were unreliable in predicting dynamically stable structures; hence prediction of ΔEHOMO-LUMO values was not possible for several PAHs. Changes in the HOMO-LUMO gap of benzene and selected PAHs due to solvation effects were calculated using self-consistent reaction field methods and explicit solvation. Self-consistent isodensity polarized continuum model calculations modeling water and octanol solvation do not change calculated ΔEHOMO-LUMO values enough to affect predicted phototoxicities; thus, gas-phase values may be used for PAHs in solution and in vivo. Energetics of PAH bonding to mineral surface groups were also modeled. In some cases, interaction of PAHs with model aluminate surface defects suggests that ΔEHOMO-LUMO values may be lowered significantly by adsorption that would lower chemical stabilities. Significant increases in calculated ΔEHOMO-LUMO that would increase chemical stability of the compounds were not predicted.
On the linear driving force model for sorption kinetics of organic compounds on suspended sediment particle
Authors: Valsaraj Kalliat T , Thibodeaux Louis J 
Published: March 2010

Abstract
Sorption kinetics of hydrophobic organic compounds on suspended sediments in the water column are analyzed using the linear driving force (LDF) model. The LDF model succinctly captures the different mass transfer resistances for uptake by aqueous suspended particles. The LDF model is appropriate for those situations where both water- and particle-side processes are important. It is shown that departure from equilibrium sorption may be responsible for the near constancy in experimental sorption coefficients obtained for strongly hydrophobic compounds towards aqueous suspended particles in the sedimentary environment. The time to equilibrium for sorption diminishes with decreasing particle radius and increases with increasing compound hydrophobicity. For strongly hydrophobic compounds, the apparent partition coefficient is shown to be inversely proportional to the suspended solids concentration when sorption is far from equilibrium.
General radial diffusion model for heterogeneous sorbents
Authors: Heyse Edward C , Mika Daniel J , De Venoge Thomas P , Coulliette David L , McGowin Audrey 
Published: March 2010

Abstract
Sorption kinetics modeling can be improved by accounting for sorbent heterogeneity. This paper demonstrates how heterogeneity can be accommodated with a composite sorbent particle whose shape is described by a general radial geometry. Batch experiments involving sorption and desorption of anthracene from paraffin spheres are used to test the model. The performance of the model is also demonstrated with simulations based on Borden soil. Experiments and modeling demonstrated that sorption by a heterogeneous mix of sorbent particle sizes can be predicted better using a general composite radial geometry than as an equivalent sphere geometry. However, predicting the composite geometry (shape factor and radius) from sorption rate data is difficult due to the nonuniqueness of sorption rate curves that evolve from higher shape factor geometries. Use of models such as ours that better describe sorption sites at long diffusion path lengths may improve predictions when slow, long-term desorption is an important factor.
Sorption–desorption behavior of phenanthrene elucidated by pyrolysis–gas chromatography-mass spectrometry studies of soil organic matter
Authors: Schultz Liese F , Young Thomas M , Higashi Richard M 
Published: March 2010

Abstract
Commonly used partitioning models of hydrophobic organic contaminant sorption in soil, which treat all soil organic matter (SOM) as having identical structure, are unable to explain differences in organic carbon–normalized sorption coefficients (KOC) among sorbents, isotherm nonlinearity, and sorption–desorption hysteresis. This study relates one index of SOM composition, structural fragments quantified by pyrolysis–gas chromatography-mass spectrometry, to aqueous and supercritical carbon dioxide (SC CO2) sorption–desorption parameters. Results show positive correlations between aqueous KOCs and hydrocarbon fragment peak areas and negative correlation to N- and O-containing peaks, which is consistent with hypotheses attributing sorption of phenanthrene to hydrophobic sorbent domains. Positive correlation between Freundlich n values in SC CO2 and hydrocarbon fragments with negative correlation to N- and O-containing fragments suggests that energetic heterogeneity of polar environments controls nonlinearity in this solvent of limited polarity. Aqueous sorption–desorption hysteresis appears to be surpressed by N- and O-containing moieties and correlates with decreased thermal desorption of phenanthrene at 800°. The SC CO2 extraction efficiency and, to a lesser degree, the desorption response when methanol is added as a cosolvent indicate that polar functional groups play a role in retarding phenanthrene desorption during SC CO2 extraction. Organic matter pyrolysis under varying time and temperature conditions indicates that pyrolysis fragments that do not significantly correlate with functional trends likely evolve by a different pyrolytic mechanism and are generally poorly correlated with sorption–desorption properties. The level of structural detail utilized in structure–function correlations in this work exceeds previous efforts to relate sorption behavior to sorbent structure. However, the work reveals that certain sorption parameters, notably Freundlich n values in aqueous systems, require even more detailed characterization of sorbent structures.
Correlation between biological and physical availabilities of phenanthrene in soils and soil humin in aging experiments
Authors: White Jason C , Hunter Margaret , Nam Kyoungphile , Pignatello Joseph J , Alexander Martin 
Published: March 2010

Abstract
The bioavailability of an organic compound in a soil or sediment commonly declines with the soil-chemical contact time (aging). A series of parallel desorption and bioavailability experiments was carried out on phenanthrene previously aged up to ∼100 d in Mount Pleasant silt loam (Mt. Pleasant, NY, USA) or Pahokee peat soil to determine as a function of the aging period the degree of correlation between the reduction in bioavailability and the rate and extent of desorption and the influence of soil organic matter composition on availability. The mineralization of phenanthrene by two bacteria and the uptake of phenanthrene by earthworms showed expected declines with aging. Likewise, the rate of phenanthrene desorption in the absence of organisms decreased with aging. The decline in initial rate of mineralization or desorption was nearly an order of magnitude after 50 to 60 d of aging. Plots of normalized rates of mineralization or desorption practically coincided. Similarly, plots of normalized fraction mineralized or fraction desorbed during an arbitrary period gave comparable slopes. The partial removal of organic matter from the peat by extraction with dilute NaOH to leave the humin fraction reduced the biodegradation of phenanthrene aged for 38 and 63 d as compared to the nonextracted peat, but the effect disappeared at longer incubation times. The rate of desorption from samples of peat previously extracted with NaOH or Na4P2O7 declined with aging and, for a given aging period, was significantly slower than from nonextracted peat. This work shows that the reduction in bioavailability of phenanthrene over time in soil is directly correlated with reduction of its physical availability due to desorption limitations. In addition, this study shows that removal of extractable humic substances leads to a decline in the rate of desorption and in the bioavailability of the substrate.
Increase in bioavailability of aged phenanthrene in soils by competitive displacement with pyrene
Authors: White Jason C , Hunter Margaret , Pignatello Joseph J , Alexander Martin 
Published: March 2010

Abstract
Competitive sorption to natural solids among mixtures of organic compounds has been documented in the literature. This study was conducted to determine co-solute competitive effects on the biological and physical availability of polycyclic aromatic hydrocarbons in soils after long contact periods (aging). Sterile suspensions of Mount Pleasant silt loam (Mt. Pleasant, NY, USA) and Pahokee peat soils were spiked with phenanthrene and allowed to age for 3 or 123 d before inoculation with a phenanthrene-degrading bacterium in the presence or absence of the nonbiodegradable co-solute pyrene. As expected, mineralization decreased with aging in the samples not amended with pyrene. However, addition of pyrene just prior to inoculation at 123 d significantly mitigated this decrease; that is, the extent of mineralization was greater in the 123-d pyrene-amended samples than in the 123-d nonamended samples. Parallel experiments on sterile soils showed that pyrene increased the physical availability of phenanthrene by competitive displacement of phenanthrene from sorption sites. First, the addition of pyrene increased recovery of 123-d-aged phenanthrene by mild solvent extraction. Second, addition of pyrene (at three concentrations) dramatically reduced the apparent distribution coefficient (Kappd) of several concentrations of 60-, 95-, and 111-d-aged phenanthrene. At the lowest phenanthrene and highest pyrene concentrations, reductions in the Kappd of phenanthrene in the peat soil reached 83%. The competitive displacement effect observed in this study adds further support to the dual mode model of sorption to soil organic matter. The displacement of an aged contaminant by a nonaged co-solute might also prove useful in the development of novel remediation strategies.
Using biodegradation kinetics to measure availability of aged phenanthrene to bacteria inoculated into soil
Authors: Schwartz Egbert , Scow Kate M 
Published: March 2010

AbstractThe rate of biodegradation of pollutants in soil can be limited by the pollutant's availability to microorganisms. We have developed a bioassay for the availability of phenanthrene to bacteria that degrade phenanthrene in soil. The assay uses a soil in which phenanthrene is degraded very slowly. The rate of phenanthrene mineralization in this soil may be increased substantially through bioaugmentation with a bacterial inoculum. By delaying inoculation, it is possible to manipulate the time phenanthrene is present in soil before accelerated biodegradation begins. A phenanthrene concentration much lower than the affinity constant of the inoculum is added; thus, biodegradation kinetics approach first order. Because the phenanthrene first-order rate constant for the inoculum is the same regardless of the phenanthrene residence time in soil, the change in phenanthrene availability to the inoculum can be measured over time. The availability of phenanthrene to bacteria declined in a biphasic double exponential pattern with time. The initial rapid decline in availability resembled the change in amount of phenanthrene extracted from soil with hexane-water. However, after phenanthrene had been present in the soil longer than 300 h, the fraction extracted with hexane-water declined faster than the substrate available to the bacterial inoculum, suggesting that the bacteria are able to access a pool of phenanthrene unavailable to hexane.