bluuebunny/crossref_metadata_2025 huggingface dataset:
Genotoxicity testing using the Mutatox™ assay: Evaluation of benzo[a]pyrene as a positive control
Authors: Klamer Hans J C , Villerius Leen A , Roelsma Jan , de Maagd P Gert-Jan , Opperhuizen Antoon
Published: March 2010

In a study on bioassay-directed chemical factionation of sediment extracts, problems were encountered using benzo(a)pyrene (BaP) as a positive control in the Mutatox™ bacterial genotoxicity assay. Genotoxic responses of tests with this compound, prescribed by the Mutatox supplier, could only be measured using supersaturated concentrations that exceeded its aqueous solubility more than 250 times. Additional to three obvious requirements for a positive control of this test system (it should demonstrate that the bacteria are alive and grow after reconstitution, that the bacteria are mutated, and that the bacteria emit light), a positive control should meet two criteria: the metabolic routes of genotoxic response induction for positive control and test compound(s) should be identical, and test concentrations (of both positive control and test compound) should be at environmentally relevant concentrations, i.e., below the aqueous solubilities. As BaP does not meet this last criterion, it does not fully qualify as a positive control in testing genotoxicity of solutes with the Mutatox assay. Testing of other unsubstituted polycyclic aromatic hydrocarbon (PAHS) did not yield another PAH as choice for positive control. Furthermore, the results of our study imply that calculating the bioavailability of BaP from the aqueous solubility alone is not sufficient, as this tends to underestimate the amount of BaP available to either the S9 enzyme system or the bacteria, whereas the interference between toxic and genotoxic effects hampered the interpretation of test results, as variations in toxicity may be interpreted as variations in genotoxicity. Quantitative S9-mediated genotoxicity assessments using the Mutatox test appeared difficult to make, as the two parameters that are proposed by the supplier (CMR, concentration of maximum genotoxic response, and LOEC, lowest observable [genotoxic] effect concentration) showed significant dependency on the sensitivity of the S9 system toward the test compound (CMR) or the initial test compound concentration (LOEC).
Kinetic evaluation of the effects of bioavailability of organic ligands on biodegradation in the presence of common sesquioxide grain coatings
Authors: Brooks Scott C , Mills Aaron L , Herman Janet S , Hornberger George M
Published: March 2010

Radionuclides and metals can be mobilized by chelating agents typically present in low-level radioactive liquid wastes that are disposed of in shallow land trenches; persistence of the organic chelating agent in the subsurface environment is a critical control on solubilization and transport of the complexed nuclide. Low-molecular-weight organic compounds are susceptible to uptake by bacteria, yet the biodegradation rates of nuclide-ligand complexes in a mixture of solids (soil minerals) and liquids (ground water) are poorly known. We investigated the rate of citrate uptake in the presence of cobalt by a mixed bacterial community under experimental conditions designed to explore the impacts of citrate concentration, temperature, and chemistry of mineral surfaces. Dilute solutions with a typical sandy-aquifer groundwater composition and equimolar amounts of cobalt and citrate ranging from 4 to 320 μM were combined with four different sand treatments: uncoated quartz sand, Fe-coated quartz sand, Mn-coated quartz sand, and no sand. Mineralization (net 14CO2 produced) and assimilation (14C retained on a 0.2-μm filter) were quantified. Initial rates of citrate mineralization and of assimilation were independent of temperature in the presence of Fe- and Mn-coated sands but were lower at lower temperatures (15°C versus 25°C) for the no-sand and the uncoated sand, but the fraction of total carbon taken up (respiration plus assimilation) that the cells assimilated was greater at 15°C than at 25°C. In the presence of Fe-coated sand, the mixed culture assimilated a greater fraction of carbon at both temperatures. The van Slyke equation, based on a model of sequential irreversible reactions, was fit to the results of the heterotrophic uptake experiments. The estimated value of the van Slyke constant indicated that mass-transfer constraints limited the overall rate of citrate uptake, and that biokinetic limitations became more important at the lower temperature for the no-sand and uncoated sand treatments. The sorption of citrate to the sand surface did not limit the rate of uptake. Further, complexation with cobalt did not alter the rate of citrate degradation or the rate of bacterial growth. The results suggest that transmembrane citrate transport limited the rate of uptake. The benefit that the bacteria derived from being associated with the solid sand surface was not directly related to the extent of citrate sorption, but might have resulted from a local elevation in the concentration of nutrients (e.g., P or N) available to the adsorbed bacteria, which may have allowed a more efficient processing of carbon into biomass. Sesquioxide coatings enhance the sorptive properties of the mineral grains, and in these experiments, the bacteria derived benefit from being associated with the solid sand surface.
Chromium(VI) toxicity to luminescent bacteria
Authors: Villaescusa Isabel , Marti Salvi , Matas Carme , Martine Maria , Ribó Josep M
Published: March 2010

The toxicity of chromium(VI) to luminescent bacteria was determined using the Microtox® bioassay. The aim of this study was to assess the influence of pH on the toxicity of Cr(VI) samples because its speciation depends on this parameter. A Microtox test basic protocol, modified to assure the same pH in all the cuvettes, was used to determine the toxicity of the Cr(VI) compounds. In the range studied, 4.6 to 9.3, the observed EC50 values increased with the pH (31–1,184 mg/L Cr(VI)). These toxicity results were related to the percentage of the different Cr(VI) species. Hydrogenchromate anion was found to be the most toxic species. In general, only slight differences in toxicity were found when the Microtox test basic protocol was used. Nevertheless, when 20.4% (w/v) sucrose was used as an alternative medium to 2% (w/v) NaCl, the results obtained could not be compared because the sensitivity of the bacteria in this medium was found to be different. The influence of an exposure-time effect was also evaluated. In 2% (w/v) NaCl medium, the toxicity increased with time, which indicates a slow response of the bacteria to the toxin.
Aquatic toxicity of eighteen phthalate esters
Authors: Staples Charles A , Adams William J , Parkerton Thomas F , Gorsuch Joseph W , Biddinger Gregory R , Reinert Kevin H
Published: March 2010

The extensive database of acute and chronic aquatic toxicity data for 18 phthalate esters was reviewed and summarized for freshwater and saltwater aquatic microorganisms, algae, invertebrates, and fish. Phthalate esters have been tested with six species of microorganisms, including bacteria and protozoans. Fifteen algal species have been tested, including green and bluegreen algae in both freshwater and saltwater. Nineteen freshwater and saltwater invertebrate species inhabiting surface waters and sediments and 21 freshwater and saltwater fish inhabiting cold and warm water bodies have been tested. The results of most studies indicate that acute and chronic toxicity to microorganisms, algae, aquatic invertebrates, and fish are limited to the lower molecular weight phthalate esters (i.e., dimethyl-, diethyl-, diallyl-, dipropyl-, dibutyl-, diisobutyl-, and butylbenzylphthalate). In contrast, higher molecular weight phthalate esters are not acutely or chronically toxic to aquatic organisms. Although conflicting data on chronic effects for high molecular weight phthalate esters have been reported for daphnids, these inconsistencies are attributed to physical effects imposed on daphnids when exposed to test concentrations in excess of true water solubilities. Altogether, nearly 400 test results covering more than 60 species of microorganisms, algae, invertebrates, and fish are reported for both freshwater and saltwater aquatic species. While most investigators used several common species and standard protocols to assay conventional endpoints, many nontraditional species and toxicological endpoints were also used. This has created a toxicological database of both sufficient depth to compare many similar tests and sufficient breadth to encompass virtually all important types of aquatic habitats and classes of aquatic species.
Glucocorticoid-xenobiotic interactions: Dexamethasone-mediated potentiation of cytochrome P4501A induction by β-naphthoflavone in a fish hepatoma cell line (PLHC-1)
Authors: Celander Malin , Bremer Jessica , Hahn Mark E , Stegeman John J
Published: March 2010

The induction of CYP1A by the polycyclic aromatic hydrocarbon (PAH)-type inducer β-naphthoflavone (BNF) in the Poeciliopsis-lucida hepatocellular carcinoma cell line (PLHC-1), and the effects of the glucocorticoid receptor (GR) agonist dexamethasone (DEX) on this response were examined. Dose-response studies revealed that BNF is three orders of magnitude less potent than the planar halogenated aromatic hydrocarbon 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as an inducer of the CYP1A activity ethoxyresorufin-O-deethylase (EROD), and that the apparent efficacy for the induction by BNF is 50% of that obtained with TCDD. Addition of 10 μM DEX resulted in potentiation of CYP1A induction at all doses of BNF tested. The degree of that potentiation of induction of CYP1A protein levels and EROD activity differed substantially between doses of BNF and at different times of exposure. For example, the maximal degree of potentiation of EROD induction by DEX was 12-fold in PLHC-1 cells treated with 0.1 μM BNF, 19-fold in cells treated with 1 μM BNF, and 8-fold in cells treated with 10 μM BNF. These maximal degrees of potentiation of EROD induction were obtained after 30 h with 0.1 μM BNF, 48 h with 1 μM BNF, and 72 h with 10 μM BNF. These results demonstrate interactions between GR and aryl hydrocarbon receptor pathways that could influence the response of fish to xenobiotic exposure.
MFO induction in fish by spent cooking liquors from kraft pulp mills
Authors: Hodson Peter V , Maj M K , Efler S , Burnison B K , van Heiningen A R P , Girard R , Carey J H
Published: March 2010

Within bleached kraft mills, the main sources of compounds inducing the mixed function oxygenase (MFO) activities of fish are waste cooking liquor, black liquor, and effluents from the first stages of the bleaching process. We measured the potency for MFO induction in rainbow trout (Oncorhynchus mykiss) of black liquors from pulp mills using kraft pulping and either softwood or hardwood furnish. Concentrations causing induction ranged from 0.0032 to 0.2%(v/v), and below critical thresholds, concentration-response relationships were linear. Above threshold concentrations, activity declined, and lethality occurred at concentrations greater than 0.1% (v/v) black liquor during 4-d exposures. Hardwood pulping generated black liquor that was less potent than that from softwood, but much of the difference was due to a higher water content; hardwood black liquor was more dilute as indicated by normalizing results to dissolved organic carbon. Compounds inducing MFO activity may be natural wood extractives associated with wood resins, or compounds created by the digestion of lignin. A high potency of black liquor from alcohol pulping supports the hypothesis of a natural compound because alcohol extraction does not chemically alter lignin to the same extent as kraft pulping; inducing compounds can also be extracted from wood chips with dichloromethane. The high potency of black liquor compared to bleaching or extraction-stage effluents suggests that control of black liquor losses may be very important in limiting exposure of fish to inducing compounds.
Ecotoxicology of arsenic in the marine environment
Authors: Neff Jerry M
Published: March 2010

Arsenic has a complex marine biogeochemistry that has important implications for its toxicity to marine organisms and their consumers, including humans. The average concentration of total arsenic in the ocean is about 1.7 μg/L, about two orders of magnitude higher than the U.S Environmental Protection Agency's human health criterion (fish consumption) value of 0.0175 μg/L. The dominant form of arsenic in oxygenated marine and brackish waters is arsenate (As V). The more toxic and potentially carcinogenic arsenite (As III) rarely accounts for more than 20% of total arsenic in seawater. Uncontaminated marine sediments contain from 5 to about 40 μg/g dry weight total arsenic. Arsenate dominates in oxidized sediments and is associated primarily with iron oxyhydroxides. In reducing marine sediments, arsenate is reduced to arsenite and is associated primarily with sulfide minerals. Marine algae accumulate arsenate from seawater, reduce it to arsenite, and then oxidize the arsenite to a large number of organoarsenic compounds. The algae release arsenite, methylarsonic acid, and dimethylarsinic acid to seawater. Dissolved arsenite and arsenate are more toxic to marine phytoplankton than to marine invertebrates and fish. This may be due to the fact that marine animals have a limited ability to bioconcentrate inorganic arsenic from seawater but can bioaccumulate organoarsenic compounds from their food. Tissues of marine invertebrates and fish contain high concentrations of arsenic, usually in the range of about 1 to 100 μg/g dry weight, most of it in the form of organoarsenic compounds, particularly arsenobetaine. Organoarsenic compounds are bioaccumulated by human consumers of seafood products, but the arsenic is excreted rapidly, mostly as organoarsenic compounds. Arsenobetaine, the most abundant organoarsenic compound in seafoods, is not toxic or carcinogenic to mammals. Little of the organoarsenic accumulated by humans from seafood is converted to toxic inorganic arsenite. Therefore, marine arsenic represents a low risk to human consumers of fishery products.
Use of plant and earthworm bioassays to evaluate remediation of soil from a site contaminated with polychlorinated biphenyls
Authors: Meier John R , Chang Lina W , Jacobs Scott , Torsella Joni , Meckes Mark C , Smith M Kate
Published: March 2010

Soil from a site heavily contaminated with polychlorinated biphenyls (PCBs) was treated with a pilot-scale, solvent extraction technology. Bioassays in earthworms and plants were used to examine the efficacy of the remediation process for reducing the toxicity of the soil. The earthworm toxicity bioassays were the 14-d survival test and 21-d reproduction test, using Lumbricus terrestris and Eisenia fetida andrei. The plant bioassays included phytotoxicity tests for seed germination and root elongation in lettuce and oats, and a genotoxicity test (anaphase aberrations) in Allium cepa (common onion). Although the PCB content of the soil was reduced by 99% (below the remediation goal), toxicity to earthworm reproduction remained essentially unchanged following remediation. Furthermore, phytotoxicity and genotoxicity were higher for the remediated soil compared to the untreated soil. The toxicity remaining after treatment appeared to be due to residual solvent introduced during the remediation process, and/or to heavy metals or other inorganic contaminants not removed by the treatment. Mixture studies involving isopropanol and known toxicants indicated possible synergistic effects of the extraction solvent and soil contaminants. The toxicity in plants was essentially eliminated by a postremediation, water-rinsing step. These results demonstrate a need for including toxicity measurements in the evaluation of technologies used in hazardous waste site remediations, and illustrate the potential value of such measurements for making modifications to remediation processes.
Dietary absorption of sediment-bound fluoranthene by a deposit-feeding gastropod using the 14C:51Cr dual-labeling method
Authors: Forbes Valery E , Forbes Thomas L
Published: March 2010

Polycyclic aromatic hydrocarbons (PAH) constitute a broad class of toxic, environmentally persistent, particle-reactive organic compounds that are ubiquitous in aquatic and terrestrial ecosystems. This study was designed to measure ingestion and dietary absorption of the PAH, fluoranthene, by two genotypes of a deposit-feeding gastropod using the 14C:51Cr dual-labeling method. Sediment processing rate, fluoranthene ingestion rate, selective ingestion of fluoranthene-containing particles, and fluoranthene absorption rate varied as a function of snail body size and genotype. Absorption efficiency of sediment-bound fluoranthene did not vary as a function of body size but differed between genotypes, averaging 42 to 46% for Clone A and 22 to 36% for Clone B. We could detect no significant metabolism of ingested fluoranthene to dissolved organic carbon or CO2 during 24 h following its ingestion. The 14C:51Cr dual-labeling method provides a powerful approach for investigating the dietary absorption of sediment-bound contaminants by (1) allowing the calculation of ingestion selectivity, sediment processing rate, contaminant ingestion rate, and absorption efficiency in individual, small invertebrates; (2) permitting estimation of the fraction of ingested/absorbed contaminant that is metabolized and released via different routes following its ingestion; and (3) facilitating evaluation of the relative importance of porewater versus ingested sediment as routes of contaminant uptake by animals.
Relationship of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran levels to stable-nitrogen isotope abundance in marine birds and mammals in coastal california
Authors: Jarman Walter M , Sydeman William J , Hobson Keith A , Bergqvist Per-Anders
Published: March 2010

Levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in common murre (Uria aalge), Brandt's cormorant (Phalacrocorax penicillatus), rhinoceros auklet (Cerorhinca monocerata), and pigeon guillemot (Cepphus columba) eggs, and Steller sea lion (Eumetopias jubatus) blubber collected from the Gulf of the Farallones National Marine Sanctuary in 1993. In addition, the samples were analyzed for stable-nitrogen isotopes (δ15N). Of the PCDDs and PCDFs, the 2,3,7,8-TCDD (TCDD) and 2,3,7,8-TCDF (TCDF) congeners were the most prominent in the birds. The levels of TCDD in the eggs ranged from 0.2 to 6.6 ng/wet kg in the pigeon guillemot and Brandt's cormorant, respectively. The TCDF ranged from 0.30 to 2.25 ng/kg in the pigeon guillemot and Brandt's cormorant eggs, respectively. Other prominent PCDD and PCDF congeners detected in all bird species were 1,2,3,6,7,8-HxCDD, 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD, and 1,2,3,4,6,7,8-HpCDD. In the Steller sea lion the most prominent congeners were 1,2,3,7,8-PeCDD at 3.2 ng/kg, 2,3,7,8-TCDD at 2.9 ng/kg, OCDF at 2.2 ng/kg, 1,2,3,6,7,8-HxCDD at 1.92 ng/kg, and 1,2,3,4,7,8-HxCDF at 1.3 ng/kg. Stable-nitrogen values ranged from 16.9‰ in the pigeon guillemot and rhinoceros auklet to 19.8% in the Steller sea lion.
Effects of life stage, substrate, and crop position on the exposure and susceptibility of Aphidius rhopalosiphi DeStefani-perez (Hymenoptera: Braconidae) to deltamethrin
Authors: Longley Martin , Jepson Paul
Published: March 2010

Laboratory bioassays were carried out to determine the toxicity of deltamethrin residues to the aphid parasitoid Aphidius rhopalosiphi DeStefani-Perez (Hymenoptera: Braconidae) on glass and foliar substrates. Residual toxicities were compared by iterating sequences of lethal dose ratios between LD10 and LD90 from the dose–response statistics for each substrate. The calculated mean ratios were termed “toxicity factors” (Tf). The Tf values indicated that the toxicity of deltamethrin residues on glass plates was 1.3 times greater than on cereal flag leaves. Parasitoid mortality was reduced by lowering the deltamethrin concentration and parasitoid exposure period. Individuals exposed to field concentrations for less than 1 h recovered when exposure ceased. Parasitoid emergence from hosts was reduced by deltamethrin at field concentrations; however, the fecundity of surviving females did not differ from controls. Deltamethrin applied at half rate had no effect on parasitoid emergence. Spray deposition on aphid mummies within a mature winter wheat canopy varied significantly with leaf position. Mummies located on awns and adaxial surfaces of flag leaves received the highest deposition rates, with the lowest levels recorded for mummies on stems and abaxial leaf surfaces. The low volumes of spray solution impinging upon mummies in the field indicated that current laboratory bioassays may overestimate pesticidal effects on developing parasitoids by between 3.4- and 266-fold.
Comparison of two population-level ecotoxicological endpoints: The intrinsic (r
m) and instantaneous (r
i) rates of increase
Authors: Walthall William K , Stark John D
Published: March 2010

The instantaneous rate of increase (ri) was compared to the intrinsic rate of increase (rm) as an alternative population-level ecotoxicological endpoint. The terrestrial arthropod Acyrthosiphon pisum Harris, the pea aphid, was used as the model species and the new nicotinergic insecticide, imidacloprid, as the xenobiotic. In the first experiment, rm was generated each day from a life table for A. pisum neonates exposed to nontreated (control) potted broad bean, Vicia faba L. (variety Banner), and compared to determine the earliest rm which was not significantly different from the final rm. The rm for neonates introduced to nontreated plants was significantly different on days 6 and 7 but not significantly different between 8 to 40 d postintroduction. A second experiment examined the change in ri over time for neonates introduced at birth to nontreated broad bean and censused at 8, 11, 13, 15, 17, 19, and 21 d postintroduction. The ri for neonate populations introduced to nontreated broad bean peaked on days 11 and 19. The ri on nontreated beans was significantly different (p < 0.05) from rm on days 8 and 15 but not significantly different at 11, 13, 17, 19, and 21 d. A third experiment was conducted comparing rm and ri following 11 d exposure to a range of imidacloprid concentrations applied to broad bean. There was a high correlation (r = 0.91, n = 21, p < 0.01) between ri and rm 11 d after the start of the study, suggesting that ri can be used as a predictive measure in place of rm. There was a negative relationship, y = 0.32 – 0.43x (r2 = 0.88, n = 21), between ri and exposure to imidacloprid-treated broad bean, suggesting that simple regressions may be utilized as tools in the assessment of xenobiotics on population growth rates.
The bioaccumulation of polynuclear aromatic hydrocarbons by benthic invertebrates in an intertidal marsh
Authors: Maruya Keith A , Risebrough Robert W , Horne Alexander J
Published: March 2010

Biota-sediment accumulation factors (BSAF; concentration in organism lipid/concentration in sediment on an organic carbon basis) of polyaromatic hydrocarbons varied with season and along an intertidal gradient in a coastal marsh in San Francisco Bay. The BSAFs were lowest during the local rainy season. During the dry season, BSAFs were lowest in the high intertidal zone closest to shore. Significant differences among species groups were also observed; BSAFs were lowest in polychaetes and highest in the asian clam (Potamocorbula amurensis), varying over almost three orders of magnitude (0.0069-5.4 g sediment organic C/g lipid). The BSAFs decreased with increasing percent fines in the sediments and with PAH concentrations on an organic carbon basis. We suggest that a determining variable is the content of highly aromatic soot particles, which increases during periods of surface runoff and which is expected in the dry season to be highest in the high intertidal zone where these finer particles preferentially accumulate. Correlations of BSAFs with the ratio of the logarithm of the activity coefficients in porewaters to those in sediments were generally stronger than with log Kow, indicating a limitation of octanol as a surrogate for sediment organic carbon or organism lipid. These observations qualify but also strengthen the concept of equilibrium partitioning as the determining factor in bioaccumulation by benthic organisms of nonpolar organic compounds from sediments; the assumption that “organic carbon” can be considered in generic terms without allowance for aromaticity and probably other factors as well, must, however, be reconsidered.
Utility of four strains of white-rot fungi for the detoxification of 2,4,6-trinitrotoluene in liquid culture
Authors: Donnelly Kirby C , Chen Jinchuan C , Huebner Henry J , Brown Kirk W , Autenrieth Robin L , Bonner James S
Published: March 2010

The purpose of this study was to investigate the potential of four different strains of white-rot fungi (Phanerochaete chrysosporium, Phanerochaete sordida, Phlebia brevispora, and Cyathus stercoreus) to degrade 2,4,6-trinitrotoluene (TNT) in liquid medium. Loss of TNT from the culture medium was determined using high-performance liquid chromatography (HPLC), while the mutagenicity of the medium residues was evaluated using the Salmonella/microsome bioassay. The data indicate that within 21 d of incubation, all fungi were able to reduce the TNT concentration (from 90 mg/L) in the liquid medium to below detection limits. In this study, P. sordida showed a relatively high growth rate and the fastest rate of TNT degradation. The fungal treatment also produced a significant reduction of TNT mutagenicity. Treatment with C. stercoreus, P. brevispora, P. sordida, and P. chrysosporium resulted in the elimination of 94%, 90%, 87%, and 67% of the initial TNT-amended medium mutagenicity, respectively. The data also demonstrate that during incubation, TNT was eliminated from the culture medium two to eight times faster than the reduction in mutagenic potential. These results suggest that TNT disappearance alone cannot be used as the sole criterion in TNT remediation. Chemical analysis revealed that the major metabolites in the initial transformation of TNT were the monoamino-dinitrotoluenes, which were also degraded by the selected white-rot fungi. The study demonstrated that the white-rot fungi are capable of metabolizing and detoxifying TNT under aerobic conditions in nonligninolytic liquid medium.
Characterization of metallothionein-like proteins from zebra mussels (Dreissena polymorpha)
Authors: High Kim A , Barthet Veronique J , McLaren James W , Blais Jean-Simon
Published: March 2010

Zebra mussels (Dreissena polymorpha) are freshwater mollusks that have recently infested the Great Lakes ecosystem. Possessing a large capacity for filtration, these mussel populations act as bioconcentrators for contaminants, such as heavy metals, found in the Great Lakes ecosystem. Metallothionein is a low-molecular-weight, heavy metal-binding protein found in most living organisms. Characterization and partial purification of metallothionein-like Cd-binding proteins from zebra mussels were performed. Zebra mussels were exposed to 500 μg/L Cd for 14 d. During the exposure period, two mussels were removed on alternate days for analysis of Cd-binding proteins. Gel-filtration high-performance liquid chromatography-microatomization-atomic absorption spectrophotometry results showed a single Cd-binding molecular weight protein fraction after 2 d of Cd exposure. After 10 d of Cd exposure, however, mussels exhibited an additional, higher molecular weight, Cd-binding protein fraction. The lower molecular weight metallothionein-like Cd-binding protein was further isolated and purified by acetone fractionation, Sephadex G75, and diethylaminoethyl anion-exchange chromatography. The quantities of Zn, Cu, and Cd in the anion-exchange metallothionein-like protein isoforms were determined by inductively coupled plasma-mass spectrometry. The ability to bioconcentrate heavy metals in a metallothionein-like form coupled with their large population in the Great Lakes make zebra mussels suitable for use in a freshwater biomonitoring program for aquatic metal contamination.
A principal-component and least-squares method for allocating polycyclic aromatic hydrocarbons in sediment to multiple sources
Authors: Burns William A , Mankiewicz Paul J , Bence A Edward , Page David S , Parker Keith R
Published: March 2010

A method was developed to allocate polycyclic aromatic hydrocarbons (PAHs) in sediment samples to the PAH sources from which they came. The method uses principal-component analysis to identify possible sources and a least-squares model to find the source mix that gives the best fit of 36 PAH analytes in each sample. The method identified 18 possible PAH sources in a large set of field data collected in Prince William Sound, Alaska, USA, after the 1989 Exxon Valdez oil spill, including diesel oil, diesel soot, spilled crude oil in various weathering states, natural background, creosote, and combustion products from human activities and forest fires. Spill oil was generally found to be a small increment of the natural background in subtidal sediments, whereas combustion products were often the predominant sources for subtidal PAHs near sites of past or present human activity. The method appears to be applicable to other situations, including other spills.
Hydrolytic release of bound residues from composted soil contaminated with 2,4,6-trinitrotoluene
Authors: Thorne Philip G , Leggett Daniel C
Published: March 2010

Samples of composted soil were extracted with solvent, then hydrolyzed with acid or base. The concentrations of extractable, unbound 2,4,6-trinitrotoluene and its mono- and diamino metabolites fell rapidly after the first days of composting. Hydrolysis of the extracted residues released significant quantities of intact metabolites.
Interpretation of Microtox® solid-phase toxicity tests: The effects of sediment composition
Authors: Ringwood Amy H , DeLorenzo Marie E , Ross Philippe E , Holland A Fred
Published: March 2010

During pilot year studies for the Estuarine Monitoring and Assessment Program (EMAP) in the Carolinian Province, it was observed that estuarine sediments characterized by high silt-clay content (contaminated as well as uncontaminated) consistently had low Microtox® EC50s (as measured by decreased light production). It was hypothesized that the low EC50 values associated with silty sediments were due to adsorption of the bacteria to the silt-clay particles. During the assay, the bioluminescent bacteria are exposed to a sediment suspension, and the effects on light production are evaluated in the liquid phase that remains after removal of the sediments by filtration. If the bacteria adsorb to the sediments, then the decreased light production observed with silty sediments may be the result of significant bacterial removal, rather than toxicity. This sediment bias could affect the interpretation of results from field studies by overestimating the potential for contaminant effects in muddy areas. We report on studies in which artificial sediments (mixtures of pure sand and clay) were used to evaluate the effects of sediment type (in the absence of contaminants) on Microtox EC50 values and bacterial counts of the liquid phase. The results supported the hypothesis. Microtox EC50s and bacterial concentrations in the liquid phase decreased in a predictable manner as clay composition increased. Methods of normalizing for sediment composition and developing toxicity criteria are discussed.
Bioremediation of TNT-contaminated soil: A laboratory study
Authors: Widrig David L , Boopathy Ramaraj , Manning John F
Published: March 2010

This research presented a bench-scale investigation of an innovative approach to land farming for the bioremediation of 2,4,6-trinitrotoluene (TNT)-contaminated soils. Molasses, which contains sugar, nitrogen, vitamins, and minerals, was used as cosubstrate and this process combines several advantages of conventional land farming with the use of molasses for the biological degradation of TNT and its derivatives. In the optimum treatment, contaminated soil was amended with shredded grass and managed in an operating cycle where it was alternatively flooded with a dilute molasses solution, then drained, passively aerated, and finally tilled when moisture conditions were optimum. Soil TNT concentrations in all treatments receiving molasses were reduced from approximately 4,000-mg/kg levels initially to less than 100 mg/kg in 12 months, and to less than 1 mg/kg in the optimum treatment in this same time. Concentrations of the primary metabolic intermediates and bacterial populations were also tracked. Radiolabeling studies confirmed that the biomass enhanced by the treatments could mineralize approximately 20% of [14C] from a contaminant spike after 22 d. A shredded grass amendment in the optimum treatment was shown to increase moisture retention during aeration phases. The results of this bench-scale study are promising with regard to transferring the process to full-scale applications.
Chironomus tentanslife-cycle test: Design and evaluation for use in assessing toxicity of contaminated sediments
Authors: Benoit Duane A , Sibley Paul K , Juenemann Jamie L , Ankley Gerald T
Published: March 2010

The development and standardization of toxicity test methods for assessing toxicity of contaminated freshwater sediments has focused predominantly on short-term exposures and lethality. In many situations, however, toxicity is more likely to become manifest over long periods of time so there is need for standardized testing procedures by which sublethal sediment toxicity can be adequately assessed. In this study, we present and evaluate a new life cycle test, using the midge Chironomus tentans, which enables the assessment of sublethal toxicity of contaminated sediments. In designing the life cycle test, our goal was to make the assay relatively straightforward and, to the extent possible, methodologically compatible with the standard 10-d test. The test is initiated with newly hatched (<24 h) larvae and uses four effects-based endpoints to assess toxicity: survival, growth, emergence, and reproduction. Survival is determined at 20 d and at the end of the test by back-calculating through emergence data. Growth can be determined at 20 d, which corresponds to the 10-d endpoint in the 10-d C. tentans growth test initiated with 10-d-old larvae. From day 23 to the end of the test, emergence and reproduction are monitored daily. The number of eggs per female is determined for each egg mass, which is then incubated for 6 d to determine hatching success. Each treatment in the life cycle test is terminated separately after 7 consecutive days without emergence. We evaluated the life cycle test by following one generation of C. tentans in sediments collected from the upper Mississippi River. Survival of larvae exceeded 90% at 20 d. Of these larvae, between 60 and 70% successfully emerged; survivorship among pupae and adults exceeded 85%. Mean egg production ranged from 906 to 1,107 eggs per female. The test required 65 d to complete, including pretest preparation. These data show that the C. tentans life cycle test can be used to assess sublethal toxicity accurately in contaminated sediments and provides a suitable compliment to the standard C. tentans 10-d test.
Cadmium binding in the blood plasma of two marine bivalves
Authors: Robinson William E , Ryan David K , Sullivan Patricia A , Boggs Colleen C
Published: March 2010

Cadmium tansport in the plasma of Mytilus edulis L. displays attributes similar to those previously described for Mercenaria mercenaria (L.). The majority of Cr, Cu, Ni, and Zn is partitioned in the plasma rather than the hemocytes in both species, although differences in Fe and Mn are apparent. Mussels however contain twice the number of circulating hemocytes (2.1 ± 0.8% of whole blood weight; n = 75 vs 1.2 ± 0.3%; n = 70 for the quahog) and approximately three times more plasma protein than the quahog. Titration experiments using ion-specific electrode (ISE) measurements and equilibrium dialysis (ED) experiments indicate that both species have a low-affinity, high-capacity system for the internal transport of Cd. At low blood Cd concentrations (<8.9 μM) and short dialysis times (24 h), approximately 90% of the Cd in mussel plasma is bound to plasma proteins. At higher Cd concentrations and at longer dialysis times, the percentage of free Cd increases substantially. The Cd affinity was slightly lower in mussel plasma compared to the quahog (log10K = 2.6–3.9/M vs 3.7–4.3/M), and mussel plasma CL values were appreciably lower (0.16–1.11 mmol/g protein) than those for the quahog (1.97–2.26 mmol/g protein). Both ISE and ED experiments on quahog plasma yielded similar estimates of K and CL.
Development of a cation-exchange methodology for marine toxicity identification evaluation applications
Authors: Burgess Robert M , Charles Judith B , Kuhn Anne , Ho Kay T , Patton Leslie E , McGovern Douglas G
Published: March 2010

In phase I of a standard toxicity identification evaluation (TIE) six manipulations are used to characterize toxicity. The ethylenediaminetetraacetic acid addition manipulation is most often used to indicate toxicity caused by divalent metals. An alternative approach for characterizing/identifying metal toxicity is the use of cation-exchange chromatography. In this study, five cation-exchange media were compared to develop a method for using cation-exchange chromatography as part of a marine TIE. To be considered useful the cation-exchange media must meet the following criteria: (1) consistently (with minimal variability) extract and elute toxic concentrations of a mixture of metals spiked into seawater, (2) demonstrate negligible blank acute toxicity, and (3) function effectively with environmental samples. Two solid-phase extraction media met the criteria: Supelco's LC-WCX column and Alltech's Extract-Clean IC-Chelate column. In general, these columns were able to remove 80 to 100% of five metals (Cd, Cu, Ni, Pb, Zn) from spiked seawater, and 85 to 100% of metals could be eluted back into solution (except copper for which recovery was 65–75%). Columns functioned effectively with seawater spiked with metals concentrations approaching 600 μg/L and showed low intercolumn variability (coefficient of variation = 1.0–14%). For actual environmental samples, once column breakthrough was assessed, both columns reduced toxicity and metal concentrations in postcolumn samples. Further, reconstituted column eluates were as toxic as whole samples. The methodology described can be used to assist in the TIE characterization and identification of toxic metals in environmental samples.
Determining the effects of pollutants on soil faunal communities and trophic structure using a refined microcosm system
Authors: Parmelee Robert W , Phillips Carlton T , Checkai Ronald T , Bohlen Patrick J
Published: March 2010

We used a refined microcosm technique to investigate the toxicity of copper, cadmium, malathion, and the polychlorinated biphenyl, Aroclor 1254, to trophic groups of soil nematodes and to the microarthropod community. Comparisons of changes in nematode abundance in control soils through time indicated that day 7 was the most appropriate time to sample the microcosms after chemical application. Nematode abundance was reduced after exposure to copper at 100 μg/g, with fungivore, bacterivore, and omnivore–predator nematodes being the most sensitive groups. Cadmium did not affect the nematode or microarthropod communities. Microarthropods were far more sensitive to malathion than were nematodes, and total microarthropod abundance was lower than controls at 400 μg/g. Prostigmatid mites and “other” arthropods were the most affected groups. Aroclor 1254 also had a greater negative impact on microarthropods than on nematodes. Total microarthropod abundance declined at 2,500 μg/g, with prostigmatid and oribatid mites exhibiting the highest susceptibility. Strong differential sensitivity between nematode and microarthropod communities indicates that both groups should be examined to fully evaluate the biological impact of chemicals on soils. We conclude that microcosms with field-collected soil microfaunal communities offer high resolution of the ecotoxicologic effects of chemicals in complex soil systems.
The effects of drilling muds on marine invertebrate larvae and adults
Authors: Raimondi Peter T , Barnett Arthur M , Krause Paul R
Published: March 2010

A series of laboratory experiments tested the effects of drilling muds from an active platform off southern California on larvae and adults of marine invertebrates. Red abalone (Haliotis rufescens) were used to determine effects of drilling muds on fertilization, early development, survivorship, and settlement, and experiments on adult brown cup corals (Paracyathus stearnsii) tested effects on adult survivorship, viability, and tissue loss. Exposures to drilling muds did not have an effect on abalone fertilization or early development. However, several exposures to drilling muds resulted in weak, but significant, positive effects of drilling muds on settlement of competent larvae. In contrast, settlement of red abalone larvae on natural coralline algal crusts decreased with increasing concentrations of drilling muds. This suggests that drilling muds affect either the abalone's ability to detect natural settlement inducers, or they affect the inducer itself. Exposure of brown cup corals to concentrations of drilling muds adversely impacted their survivorship and viability. These effects were likely caused by increased tissue mortality of the coral polyps.
METIER (modular ecotoxicity tests incorporating ecological relevance) for difficult substances. 4. Test chamber for cladocerans in flow-through conditions
Authors: Diamantino Teresa C , Ribeiro Rui , Goncalves Fernando , Soares Amadeu M V M
Published: March 2010

Continuous-flow systems in toxicity testing are advantageous because they introduce constant toxicant concentrations and constant food to the test organisms and continuously purge wastes. Therefore, continuous-flow systems are particularly useful in hazard assessment of substances that may readily be lost from test chambers (i.e., poorly water soluble, volatile, readily biodegradable or photodegradable, hydrolitically unstable compounds). Within METIER (Modular ecotoxicity tests incorporating ecological relevance), a European Union-funded project, a basic design for a standard flow-through exposure system was developed. This paper addresses the adaptation of the flow-through system for use with cladocerans, which involved designing a suitable test chamber and appropriate operation procedures. The sublethal toxicity of a reference compound (3,4-dichloroaniline) to Daphnia magna Straus was evaluated under both flow-through and semi-static conditions. Tests conducted under flow-through conditions provided a less sensitive measure of toxicity than under semi-static conditions. This result is probably a function of the higher food availability within the flow-through system. The no-observed-effect concentration for reproduction was the most sensitive endpoint and was 5 μg/L in the flow-through system and 2.5 μg/L in semi-static conditions.
Selenium sediment toxicity thresholds and derivation of water quality criteria for freshwater biota of western streams
Authors: Van Derveer William D , Canton Steven P
Published: March 2010

Waterborne and sediment selenium (Se) data, in conjunction with selected physicochemical parameters, were collected from streams of the middle Arkansas River basin, Colorado, USA, to examine the factors affecting sediment Se accumulation in a lotic environment. An empirical model of dissolved-to-sediment Se transfer in western streams, as an interactive function of sediment organic carbon content (R2 = 0.78, p < 0.001, n = 34), was developed and validated. Sediment Se and associated biological effects data were compiled from the literature, to provide an estimate of sediment Se concentration thresholds that have biological effects. Based on this preliminary analysis, sediment Se concentrations of 2.5 μg/g would be a threshold based on predicted effects and concentrations of 4.0 μg/g would be the observed threshold for fish and wildlife toxicity. The dissolved-to-sediment Se transfer model can be used to translate this type of sediment Se toxicity threshold to a site-specific chronic water-quality standard for western streams based on empirically derived sediment total organic carbon values.
Sublethal toxic effects of cyanobacteria and nonylphenol on environmental sex determination and development in Daphnia
Authors: Shurin Jonathan B , Dodson Stanley I
Published: March 2010

In many cladoceran zooplankton, females divide their reproductive effort among females, males, and resting eggs depending on a suite of environmental conditions. Having alternative life-history strategies allows cladocerans such as Daphnia to achieve high reproductive rates asexually when conditions are favorable and to produce offspring sexually for survival when the environment becomes unsuitable. Because of their rapid reproduction, Daphnia and other cladocerans are useful model organisms in aquatic toxicology. Bioassays using Daphnia serve two functions, to estimate the ecosystem level risk posed by specific chemicals and to quickly detect contaminated waters. Bioassays examine effects in terms of life history features such as growth, survival, and asexual fecundity. We studied the effects of toxic stress on Daphnia galeata mendotae grown under conditions in which it produces female, male, and ephippial offspring. Fecundities in terms of the three types of offspring showed different sensitivities to chemical stress. The stressors were a toxic strain of the cyanobacterium Microcystis aeruginosa and nonylphenol, a plasticizer, which is a surfactant that interferes with endocrine function in vertebrates. Production of resting eggs and female offspring were affected in both experiments, but the experiments showed different dose responses. Production of males was less sensitive. Exposure to nonylphenol also produced a characteristic developmental abnormality at environmentally relevant concentrations. Life table analysis showed that stress during the sexual phase of the life cycle of Daphnia reduces short-term population growth and as well as affecting the stock of dormant individuals.
Long-term fate of crankcase oil in rainbow trout: A time- and dose-response study
Authors: Hellou Jocelyne , Warren William , Andrews Catherine , Mercer Graham , Payne Jerry F , Howse Douglas
Published: March 2010

Rainbow trout (Oncorhynchus mykiss) were exposed to waste crankcase oil, a recognized source of polycyclic aromatic hydrocarbon (PAH) contamination in urban runoff. Dietary exposure was to a mean concentration of 0, 3.5, 8.9, and 13 μg oil/g fish, and sampling took place after 3, 7, 11, and 15 weeks. The accumulation of compounds in muscle tissue, the elimination of bile metabolites, the activity of 7-ethoxyresorufin O-deethylase (EROD) in liver, and morphometric variables were compared at the different concentrations and times of sampling. The concentration of fluorescing compounds in muscle displayed the best dose- and time-response pattern, whereas other biological, chemical, and biochemical responses were not as well defined. No correlation could be drawn between the concentration of PAH in the oil and the measured variables. The environmentally relevant concentrations used in the experiment show the importance of choosing broad and specific indicators of exposure in a multidisciplinary investigation and the need for further research in chemical and toxicologic areas.