bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecotoxicological assessment of solid wastes: A combined liquid- and solid-phase testing approach using a battery of bioassays and biomarkers
Authors: Ferrari Benoit , Radetski Claudemir Marcos , Veber Anne-Marie , Ferard Jean-Francois
Published: March 2010

Municipal solid waste incinerator bottom ash (MSWIBA) was used as a test matrix for comparing the responses of different variables (solid phase vs leachate media) through toxicity tests and resulting endpoints. Toxicity of leachate and solid-phase MSWIBA was evaluated with three terrestrial plants, namely oats (Avena sativa L.), Chinese cabbage (Brassica campestris L. cv. chinensis), and lettuce (Lactuca sativa L.). Assessment endpoints for these plant tests were biomass fresh weight, germination rate, and oxidant stress enzyme activities (superoxide dismutase, catalase, peroxidase, and glutathione reductase). Leachate MSWIBA toxicity was tested with bacteria (Vibrio fischeri), algae (Pseudokirchneriella subcapitata), and microcrustaceans (Daphnia magna and Ceriodaphnia dubia). A large range of toxicity responses was obtained with the various bioassays. With plant tests, the phytotoxicity of MSWIBA was revealed by the solid-phase approach, whereas no toxicity was observed with the MSWIBA leachate. The increase of oxidant stress enzyme activities was demonstrated to be a good indicator of solid or leachate phase toxicity.
Bioaccumulation kinetics of brominated flame retardants (polybrominated diphenyl ethers) in blue mussels (Mytilus edulis)
Authors: Gustafsson Kerstin , Björk Mikael , Burreau Sven , Gilek Michael
Published: March 2010

Baltic Sea blue mussels, Mytilus edulis, were exposed to polybrominated diphenyl ethers (PBDEs, IUPAC congeners 47, 99, and 153) and polychlorinated biphenyls (PCBs, congeners 31, 52, 77, 118, and 153) in a flow-through experimental setup for 44 d. After the exposure phase, the mussels were allowed to depurate in natural brackish water for 26 d. After analyses, uptake clearance rate coefficients (ku), depuration rate coefficients (kd), and bioaccumulation factors (BAF) were calculated. A rapid uptake of all PBDEs and PCBs was observed, especially for PBDE congeners 47 and 99 (ku 120 and 170 L/day/g dry weight, respectively). The depuration rate decreased with increasing hydrophobicity as expected for the PCBs, but for the PBDEs, depuration rate coefficients appeared to be of the same magnitude for all three congeners independently of log Kow. The BAFs obtained for PBDE 47 and PBDE 99 (1.3 × 106 and 1.4 × 106 ml/g dry weight, respectively) were higher than for all other substances in the study, severalfold higher than for PCBs of similar hydrophobicity. The presented data indicate that the bioaccumulation potential of PBDEs, extensively used as flame retardants, is similar or higher than that of PCBs for filter feeding organisms such as blue mussels.
Role of chemical and ecological factors in trophic transfer of organic chemicals in aquatic food webs
Authors: Russell Ronald W , Gobas Frank A P C , Haffner G Douglas
Published: March 2010

Trophic transfer of chlorinated organic contaminants was investigated in an aquatic community composed of zooplankton, benthic invertebrates, and fish. Biomagnification, measured as the increase in lipid-based chemical concentrations in predator over that in prey, was observed for high-Kow chemicals (logKow > 6.3). Low-Kow chemicals (log Kow < 5.5) did not biomagnify in the food web, and chemicals with log Kow between 5.5 and 6.3 showed some evidence of biomagnification. Trophic level differences in chemical accumulation in the food web could not be attributed to bioconcentration into increasing trophic levels with increasing lipid levels, as no relationship was observed between trophic position and lipid content of organisms. Plots of contaminant-ordinated principal component scores in component space predicted the detailed diets of the species examined. It is concluded that (1) trophic interactions play a crucial role in the distribution of high-Kow chemicals but not for low-Kow chemicals and that (2) contaminant distributions provide a means to determine structure in aquatic communities.
Elevated trace element concentrations and standard metabolic rate in banded water snakes (Nerodia fasciata) exposed to coal combustion wastes
Authors: Hopkins William A. , Rowe Christopher L , Congdon Justin D
Published: March 2010

Trace element concentrations in banded water snakes, Nerodia fasciata, and representative prey items from a site polluted by coal combustion wastes were compared with concentrations in conspecifics from a nearby reference site. Water snakes accumulated high concentrations of trace elements, especially arsenic (As) and selenium (Se), in the polluted habitat. In addition to being exposed to contaminants in water and sediments, snakes in the polluted site are exposed to contaminants by ingesting prey items that have elevated whole-body concentrations of trace elements, including As, cadmium (Cd), and Se. Snakes from the polluted site exhibited mean standard metabolic rates (SMR) 32% higher than snakes from the reference site. As a result, snakes from the polluted site appear to have elevated allocation of energy to maintenance and theoretically should have less energy available for growth, reproduction, and storage. Our findings are consistent with physiological responses recently documented in other organisms from the polluted site. We hypothesize that long-term exposure to coal ash–derived trace elements and the resultant accumulation of some elements are responsible for observed increases in SMR.
Effects of the organochlorine insecticide lindane (γ-C6H6Cl6) on the population responses of the freshwater amphipod Hyalella azteca
Authors: Blockwell Stephen J , Maund Stephen J , Pascoe David
Published: March 2010

Adult populations of Hyalella azteca, with similar reproductive potential, were exposed in the laboratory to a range of lindane concentrations below the 240-h adult LC50 (26.9 μg/L) for a period of 35 d. The reproductive status of each population was assessed through quantification of the precopulatory guarding behavior of Hyalella, the number of gravid females, and their brood sizes. At the end of the experiment, recruitment within the H. azteca populations was assessed, and the body lengths of individuals were measured using image analysis. By employing a range of integrated and quantifiable response criteria, the influence of lindane at the individual and at the population level was determined. A lowest observed effect concentration of 13.5 μg lindane/L was identified. The experimental results are discussed in relation to the reproductive strategies adopted within the treatment groups and with respect to previous toxicity data.
Use of fish gill cells in culture to evaluate the cytotoxicity and photocytotoxicity of intact and photomodified creosote
Authors: Schirmer Kristin , Herbrick Jo-Anne S , Greenberg Bruce M , Dixon D George , Bols Niels C
Published: March 2010

The influence of ultraviolet (UV) irradiation on creosote toxicity was investigated with the rainbow trout (Oncorhynchus mykiss) gill cell line, RTgill-W1, and two indicator dyes, alamar Blue™ and 5-carboxyfluorescein diacetate acetoxymethyl ester. These monitor redox potential and membrane integrity, respectively. After solubilization and chemical analysis, creosote was presented to cells in the dark to measure cytotoxicity or concurrently with UV irradiation to evaluate photocytotoxicity. Additionally, creosote was photomodified by 2 h of UV irradiation before presentation to cells in the dark or together with UV. Cytotoxicity was detected only at high nominal creosote concentrations, but photocytoxicity occurred at creosote concentrations 35-fold lower. All the aromatic hydrocarbons in creosote appeared to contribute to cytotoxicity, but photocytotoxicity was due only to the fluoranthene, pyrene, anthracene, and benzo[a]anthracene in the mixture. Photomodified creosote was much more cytotoxic than intact creosote and this difference was most pronounced in the alamar Blue assay. Likely, this was due to photomodification products that impaired the mitochondrial electron transport chain. Photomodified creosote was slightly less photocytotoxic than intact creosote. Overall these results indicate that UV irradiation potentially enhances the toxicity of creosote to fish in several different but significant ways.
Effects of chronic metal exposure and sediment organic matter on digestive absorption efficiency of cadmium by the deposit-feeding polychaete Capitella species I
Authors: Selck Henriette , Decho Alan W , Forbes Valery E
Published: March 2010

Organic matter such as humic acid and bacterial slime exopolymer are common in estuarine and coastal sediments, where they are ingested by animals that process particulate detritus. Both humic acid (HA; refractory) and exopolymer (EPS; easily digestible) bind metals and therefore might represent a source of particulate-bound metals to deposit-feeding organisms. This study examined how cadmium preexposure (3 and 30 μg Cd/g dry wt. sed.), gut passage time (GPT), and quality and quantity of the organic coating on sediment particles interact to determine cadmium absorption efficiency (Cd-AE) in Capitella sp. I. Pulse-chase experiments using 109Cd and 51Cr were used to determine Cd-AE in individual worms. Worms were given a pulse of carbon-cleaned, HA-coated or EPS-coated sediment particles. The third treatment was divided into three EPS concentrations (high, medium, and low). A 5-d preexposure to cadmium did not affect the egestion rates during either the preexposure period or the chase phase. Worms given a pulse of carbon-cleaned particles exhibited higher egestion rates during the chase phase than worms given a pulse of organic-coated particles, and no differences were seen in egestion rate between worms exposed to HA- and high-EPS-coated particles. Egestion rates decreased with increasing EPS concentration. The presence of refractory organic material decreased the absorption efficiency of cadmium from sediment relative to Cd-AE from carbon-cleaned sediment but not relative to Cd-AE from sediment coated with a high concentration of EPS. The Cd-AE increased linearly with increasing exopolymer coating on sediment particles. Overall, Cd-AE increased with increasing gut passage time in worms that were not preexposed, although Cd-AE from HA-coated particles was independent of gut passage time. Preexposure to cadmium reversed the relationship between gut passage time and cadmium absorption efficiency. Thus, the implications are that sedimentary organic matter and worm physiology might be especially important in controlling metal bioavailability in deposit-feeding organisms and should be considered in sediment quality approaches.
An investigation of the application of the Canadian water quality guidelines
Authors: Walker Sherry L , Gobas Frank A P C
Published: March 2010

The Canadian water quality guidelines for the protection of aquatic life assume that (1) the external water concentration is an effective measure of the concentration at the active site in organisms, which is ultimately responsible for a toxic response, and that (2) the safety factor accounts for any differences between laboratory and field conditions as well as the extrapolation from the effect concentration to a long-term no-effect concentration. This study examines these assumptions and assesses potential errors that environmental managers can make when applying the guidelines. The methodology is based on assessing the probability that internal concentrations of several contaminants are greater than or less than the “safe” concentration, assumed by the guideline, when the water concentration is at the water quality guideline. Results derived from empirical observations and a food-web bioaccumulation model show that a high probability (62–100%) exists that safe internal concentrations are exceeded for polychlorinated biphenyls, 1,2,4,5-tetrachlorobenzene, and hexachlorobenzene in Lake Ontario when the aqueous concentrations are at the water quality guideline values. This is due to field bioaccumulation factors being greater than the bioaccumulation factors in laboratory toxicity tests used for the water quality guideline development. Factors contributing to the exceedence of safe internal concentrations at the water quality guideline values are identified. Recommendations for improvement of the water quality guideline process are provided.
Understanding single-species and model ecosystem sensitivity: Data-based comparison
Authors: Versteeg Donald J , Belanger Scott E , Carr Gregory J
Published: March 2010

Risk assessments for compounds released to the environment typically rely on single-species toxicity studies to predict concentrations at which effects may be observed. These single-species toxicity studies are usually conducted with a few species, cultured under optimum conditions (diet, temperature, light, etc.) and tested in clean water with constant exposure to the compound of interest. Chronic toxicity data are then extrapolated to the ecosystem during risk assessments to predict concentrations that will not adversely impact the environment. Several approaches have been developed that apply statistical methods to estimate toxicant concentrations adversely affecting a small percentage of single species (e.g., 5%). There are several rarely stated, and infrequently tested, biological and statistical assumptions required to make this extrapolation. One test of the ability to use single-species toxicity data to protect ecosystems is to compare effects on single species with effects on experimental and natural ecosystems (e.g., microcosms, model ecosystems, field). Towards this end, we summarized the chronic single-species and experimental ecosystem data on a variety of substances (n = 11), including heavy metals, pesticides, surfactants, and general organic and inorganic compounds. Single-species data were summarized as genus-specific geometric means using the NOEC or EC20 concentration. Genus mean values spanned a range of values with genera being affected at concentrations above and below those causing effects on model ecosystems. Geometric mean model ecosystem no effect concentrations corresponded to concentrations expected to exceed the NOEC of 10 to 52% of genera. This analysis suggests that laboratory-generated single-species chronic studies can be used to establish concentrations protective of model ecosystem, and likely whole ecosystem, effects. Further, the use of the 5% of genera affected level is conservative relative to mean model ecosystem data but is a fairly good predictor of the lower 95% confidence interval on the mean model ecosystem NOEC.
Photochemical oxidation of terbufos
Authors: Lee Cindy M , Anderson Barbara , Elzerman Alan W
Published: March 2010

We studied the photochemical oxidation of an organophosphorus pesticide, terbufos, in surface waters because its oxidation products are of concern. Terbufos sulfoxide and terbufos sulfone have toxicities for aquatic organisms similar to those of the parent compound. We measured a photolysis rate constant under natural sunlight conditions in distilled water of 0.68±0.17/h near Clemson, South Carolina, USA. Actinometer studies resulted in a mean reaction quantum yield for terbufos of 5.8 × 10−3. The measured half-life of 64 min is considerably faster than any of the other chemical or biochemical oxidation half-lives in soil or hydrolysis half-lives reported in the literature. Photolysis should be considered in evaluating the risk of terbufos to surface waters and aquatic organisms.
Global chemical fate of α-hexachlorocyclohexane. 1. Evaluation of a global distribution model
Authors: Wania Frank , Mackay Donald , Li Yi-Fan , Bidleman Terry F , Strand Asbjørn
Published: March 2010

Vertical atmospheric layering is included in a previously described, zonally averaged global multimedia distribution model. This model is used to simulate the fate of α-hexachlorocyclohexane (α-HCH), the main ingredient of the technical HCH pesticide mixture, for the 50 years of its large-scale use (1947−1997). Worldwide historic emission estimates are compiled, assigned to 10 climate zones, and used as input in model calculations. The performance of the model is evaluated by comparing calculated and measured concentrations in the atmosphere and seawater. A major focus is on the arctic and northern temperate environment, and emphasis is also placed on absolute levels, time trends, latitudinal profiles, and air-water exchange. In general, simulated and observed concentrations agree within one order of magnitude. Deviations are explained by the zonal averaging characteristics of the model and uncertainties associated with the environmental degradation rates of α-HCH. In both model results and observations, the dramatic decrease in the global emission of α-HCH is reflected in rapidly decreasing concentrations in the atmosphere and seawater, except in the Arctic Ocean, which apparently is the last refuge for α-HCH in the global environment. The model thus provides an illustration of the response characteristics of the global system to the reduced emissions of α-HCH. Its application to other chemicals with reduced emission is discussed.
Global chemical fate of α-hexachlorocyclohexane. 2. Use of a global distribution model for mass balancing, source apportionment, and trend prediction
Authors: Wania Frank , Mackay Donald
Published: March 2010

A global distribution model that was previously shown to give satisfactory results is used to study in more detail and quantitatively the fate of α-hexachlorocyclohexane (α-HCH) in the global environment. The results provide a comprehensive historical picture of the global behavior of this chemical, which after being used in huge amounts in the early 1980s, has since been essentially eliminated. The major pathway of α-HCH from a global perspective is the transfer from the site of application to the world oceans via rivers and the atmosphere. Major reservoirs were initially the soils in regions of application and are now the world oceans. Global distribution patterns can be explained by differential persistence in various climates and meridional transport in the atmosphere and oceans. Most of the α-HCH emitted globally has been degraded in the zones of application, and only very small fractions, probably less than 1%, have survived until the mid−1990s and have reached the Arctic. However, a large fraction of the α-HCH that has survived is now present in high latitudes. The Arctic Ocean as the final reservoir for α-HCH is likely to be slowly depleted, with a half-life of approximately one decade.
Effect of Tween surfactants on methanogenesis and microbial reductive dechlorination of hexachlorobenzene
Authors: Yeh Daniel H , Pennell Kurt D , Pavlostathis Spyros G
Published: March 2010

The effect of nine Tween surfactants (polyoxyethylene sorbitan fatty acid esters) on methanogenesis and the microbial reductive dechlorination of hexachlorobenzene (HCB) was examined using three anaerobic, HCB-dechlorinating mixed cultures, one glucose fed and two lactate fed, that were derived from contaminated estuarine sediments. The two lactate-fed cultures differed significantly in their metabolic activity, especially with respect to the rate and extent of HCB reductive dechlorination. The objective of the study was to screen and select biologically compatible surfactants for use in subsequent research on surfactant-enhanced bioavailability of sorbed-phase chlorinated organic contaminants. Addition of the Tween surfactants resulted in lower rates of methanogenesis and HCB dechlorination compared with the control (i.e., surfactant-free culture) for both the glucose-fed culture and the lactate-fed culture, which exhibited a high metabolic activity. Tween−61 and −65 exhibited the lowest inhibition of HCB dechlorination at initial surfactant concentrations of 200 and 1,000 mg/L. On the other hand, the Tween surfactants, especially Tween−81 and −85, enhanced the rates of both methanogenesis and HCB dechlorination when the low metabolic activity lactatefed culture was used. The observed rate enhancements may be attributed to bacterial cell membrane modification by the surfactants. Attempts to correlate methanogenesis rates to surfactant properties (such as the hydrophile-lipophile balance number, fatty acid carbon chain length, and the number of ethylene oxide groups) were not successful. In general, increased surfactant concentrations resulted in lower rate and extent of HCB dechlorination. Although HCB dechlorination was completely inhibited at a surfactant concentration of 1,000 mg/L, the extent of methanogenesis was not affected. Results from this study demonstrate that despite compositional similarities among the Tween surfactants, their effects on biological activities, such as methanogenesis and reductive dechlorination, can differ significantly.
Assessment of DNA damage in filamentous fungi by single cell gel electrophoresis, comet assay
Authors: Hahn Alexander , Hock Bertold
Published: March 2010

The single cell gel electrophoresis (SCGE) assay, or comet assay, is a highly sensitive method to measure DNA damage. The principle of the assay is based on the conversion of single-strand breaks and alkali-labile sites to double-strand breaks via alkaline lysis. The cells are subjected to electrophoresis, stained, and microscopically evaluated. Increasing damage leads to increasing migration of DNA from the nuclei. Experiments were conducted with Sordaria macrospora grown for 3 d directly on agarose minigels in order to examine the utility of the SCGE assay for the detection of effects caused by a variety of DNA-damaging agents. When the mycelia were exposed to a variety of genotoxic conditions and analyzed by SCGE, DNA strand breaks were detected by an increase in the DNA migration distance from the nucleus. The results show that this assay allows for a fast and sensitive detection of a wide spectrum of DNA-damaging effects.
Acute aquatic life criteria for selenium
Authors: Canton Steven P
Published: March 2010

The U.S. Environmental Protection Agency's (U.S. EPA's) current acute aquatic life criterion for selenium (Se), 20 μg/L, was based on a back-calculation from the chronic criterion of 5 μg/L, using the acute-to-chronic ratio in reverse. While bioaccumulation and subsequent toxicity through dietary uptake are important factors in chronic toxicity, acute toxicity is a shortterm phenomenon, which should be promulgated with an acute value derived from direct toxicity studies, similar to other metals and metalloids. Acute toxicity values from the U.S. EPA Se criteria document were updated with more recent toxicity data for the two primary forms of Se, selenite (Se IV) and selenate (Se VI). Using this updated toxicity database, genus mean acute values were calculated, and the database was ranked based on sensitivity to both forms. Following recalculation (using U.S. EPA criteria derivation guidelines), the updated final acute value (FAV) for selenite was 437 μg/L, resulting in a criterion maximum concentration (CMC), or acute criterion, of 219 μg/L. For selenate, the FAV becomes 826 μg/L, with a CMC of 413 μg/L. Unless Se speciation studies demonstrate that the primary form of Se is selenate, the conservative assumption should be that any Se present is in the more toxic selenite form, resulting in an acute criterion for Se of 220 μg/L. These acute criteria are scientifically sound and necessary under U.S. EPA's regulatory structure for deriving National Pollutant Discharge Elimination System discharge permit limits.
Interspecies scaling of the bioaccumulation of lipophilic xenobiotics in fish: An example using trifluralin
Authors: Schultz Irvin R , Hayton William L
Published: March 2010

A poorly understood factor that may influence differences in the accumulation of a xenobiotic among fishes is interspecies differences in physiology. We have extensively studied the uptake, distribution, and excretion kinetics of the lipophilic herbicide trifluralin (TF) in fish, using a static water exposure system and compartmental toxicokinetic models. We obtained quantitative estimates of physiologically based toxicokinetic parameters such as uptake clearance, apparent volume of distribution, and elimination clearance due to xenobiotic metabolism, in rainbow trout, channel catfish, and bluegill sunfish at two acclimation temperatures. In these and other species (largemouth bass, gizzard shad, fathead minnows, and lake sturgeon), oxygen consumption rate, total lipid content, plasma protein binding, and in vitro biotransformation rates from liver homogenates were determined and examined for their capacities to predict toxicokinetic parameter values. The uptake clearance of TF was predictable based on the oxygen consumption rate, and in vitro TF biotransformation rate was a useful predictor of the in vivo metabolic clearance of TF. Lipid content, however, did not predict the apparent volume of distribution of TF. Values of uptake and metabolism clearance were predicted in largemouth bass, gizzard shad, fathead minnows, and lake sturgeon, using the oxygen consumption and the in vitro TF biotransformation rates. These predicted parameters were then used to successfully simulate the toxicokinetics of TF in these species.
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

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

Retene (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

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

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

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

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

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

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

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

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

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

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

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

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.