bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of temporal and age-related trends of chemically and biologically generated 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in lake Ontario lake trout, 1977 to 1993
Authors: Huestis Susan Y , Servos Mark R , Whittle D Michael , van den Heuvel Michael , Dixon D George
Published: March 2010

Levels of selected non-, mono-, and di-ortho-substituted polychlorinated biphenyl (PCB) congeners, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) were determined in 4-year-old lake trout from the eastern basin of Lake Ontario, collected from 1977 to 1993. Results confirm that overall levels of contaminants have decreased steadily in lake trout since 1977, and that coplanar PCB levels do not appear to be increasing over time in relation to levels of other PCBs. Contaminant levels in lake trout from 3 to 9 years old, collected in 1988 from the western end of Lake Ontario, show the body burden of contaminants increases with age. Relative levels of coplanar PCBs to other PCBs for the age study samples showed no change, except for PCB 77, which exhibited a slight decrease in relation to total PCB levels. Toxic equivalents (TEQs) were calculated from fish contaminant concentrations measured for the time study using toxic equivalence factors (TEFs) from both mammalian and teleost studies. The relative contributions of PCBs, PCDDs, and PCDFs to total TEQs were examined. When TEFs used for risk assessment are applied to temporal trend data, 15 to 20% of the total TEQs were due to mono-ortho-substituted PCBs; 40 to 50% to non-ortho coplanar PCBs; and 20 to 30% to 2,3,7,8-substituted PCDD and PCDFs. The TEQs determined from lake trout extracts by an H4IIE cell bioassay technique are compared to those determined by chemical analyses, using a variety of TEFs.
Effects of the antibiotic baytril (enrofloxacin) on pcb-initiated induction of cytochrome P4501A mRNA in sexually mature Atlantic tomcod (Microgadus tomcod)
Authors: Williams Jim , Courtenay Simon C , Wirgin Issac I
Published: March 2010

We used a factorial experimental design to determine whether the antimicrobial Baytril (enrofloxacin) had an effect on induction of cytochrome P4501A (CYP1A) mRNA in Atlantic tomcod. Fish were injected with corn oil, Baytril and corn oil, Baytril and 3,3′,4,4′-tetrachlorobiphenyl (PCB) dissolved in corn oil, or just PCB in corn oil. Analysis of gene induction in both sexes considered together showed significant induction by PCB treatment and a significant effect of sex (males higher than females). Because the experiment was carried out just before spawning, our results provide additional evidence for pretranslational suppression of CYP1A induction in spawning females. Separate analysis of the sexes showed that in both males and females, PCB had a significant effect on induction. However, in analyzing the males we also observed significant induction by Baytril alone. In addition, the BaytrilPCB combination resulted in the highest induction in any group. These findings demonstrate the potential for confounding results due to exposure of sampled fish to antibiotics, either in a laboratory or field situation.
Effects of the insecticide Dursban®4e (active ingredient chlorpyrifos) in outdoor experimental ditches: Responses of ecosystem metabolism
Authors: Kersting Kees , van den Brink Paul J
Published: March 2010

Experimental ditches were teated with Dursban®4E at nominal concentrations of 0, 0.1, 0.9, 6, and 44 μg/L of the active ingredient chlorpyrifos. Continuous oxygen, pH, and temperature measurements were made to determine the ecosystem metabolism. In addition, alkalinity and conductivity were determined weekly. Oxygen concentrations and pH were elevated at the highest treatment level. The “dissolved oxygen-pH-alkalinity-conductivity syndrome” was analyzed with the multivariate ordination technique “redundancy analysis” and indicated a temporary effect of chlorpyrifos. Whole-system gross primary production and oxygen consumption were both lowered in relation to the treatment, with oxygen consumption showing the most prominent decrease. These effects are explained as a decrease in decomposition after the arthropods are killed. The effect of chlorpyrifos on the ecosystem metabolism is slight. The influence of the state of the ecosystem on the response of ecosystem functions to insecticide treatment is also discussed.
Susceptibility of early life stages of Xenopus laevis to cadmium
Authors: Herkovits Jorge , Cardellini Pietro , Pavanati Cristina , Perez-Coll Cristina S
Published: March 2010

The susceptibility of Xenopus laevis to cadmium during different stages of development was evaluated by exposing embryos to cadmium concentrations ranging from 0.1 to 10 mg Cd2+/L for 24, 48, and 72 h and assessing lethality and malformations. Susceptibility increased from the two blastomeres stage (stage 2) to stage 40, in which the 24-h LC100 was 1.13 mg Cd2+/L, and resistence increased from this stage onward. Malformations occurred at all developmental stages evaluated, the most common being reduced size, incurvated axis, underdeveloped or abnormally developed fin, microcephaly, and microphtalmy. Scanning electron microscopy revealed changes in the ectodermal surface ranging from slightly vaulted cells to a severe reduction in the number of ciliated cells as the concentration of cadmium increased. The intraspecific variation evaluated in embryos (from four sets of parents) at seven developmental stages, expressed as the coefficient of variation of the LC100, ranged from 10 to 112% and reflects the capacity of Xenopus laevis to adapt to changing environmental conditions at different embryonic stages.
Bioaccumulation of cesium-137 in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned nuclear reactor reservoir
Authors: McCreedy Clark D , Jagoe Charles H , Glickman Lawrence T , Brisbin I Lehr
Published: March 2010

Bioaccumulation of 137Cs was investigated in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned reactor reservoir, Pond B, Savannah River Site, Barnwell Co., South Carolina. We collected fish by trap-netting, and determined ages from pectoral spines. Muscle and other tissues were assayed for 137Cs by NaI-scintillation. Muscle 137Cs was unrelated to sex (p = 0.859) or mass of fish (p = 0.224), but was related to age (p = 0.036). Examination of least-squares means suggested that 137Cs in muscle increased up to about age 3, but did not increase with greater age (means for 1, 2, 3, 4, 5, and 6 year olds were 2,630, 3,011, 3,513, 3,417, 3,599, and 3,339 Bq/kg, respectively). A modified Richards model showed equilibrium 137Cs concentration in muscle (3,625 Bq/kg) was acquired in approximately 2.4 years. Growth differed between sexes (p < 0.001), and the time to asymptotic body mass was longer than the time to attain equilibrium 137Cs concentration. Males attained an asymptotic mass of 577 g in approximately 6.3 years; females attained an asymptotic mass of 438 g in approximately 5.9 years. The cumulative 137Cs burden of the population was 4.9 × 106 Bq, representing <0.001% of the 137Cs inventory of the reservoir. Concentration of 137Cs varied among tissues (p < 0.001), with gill and muscle the lowest and highest (634 and 3,712 Bq/kg, respectively). Concentration of 137Cs in ovaries declined with increasing ovary mass (p = 0.001; r2 = 0.60). Until equilibrium is attained in these fish, 137Cs concentration is directly related to increasing age rather than size.
A comparison of the toxicity and metabolism of phenol and chlorinated phenols by Lemna gibba, with special reference to 2,4,5-trichlorophenol
Authors: Sharma Hari A , Barber John T , Ensley Harry E , Polito Michael A
Published: March 2010

The toxicity of a series of chlorinated phenols, from phenol to pentachlorophenol, was determined using frond reproduction in aseptically grown Lemna gibba. The toxicities of the phenols tended to increase as the number of chlorine substituents on the phenol ring increased. The plants metabolized each of the phenols in the same manner producing metabolites that were more polar than their parent compounds. The metabolite for 2,4,5-trichlorophenol was isolated and identified by nuclear magnetic resonance spectroscopy and chemical ionization mass spectroscopy. The structural identity was confirmed by comparison with synthetic material as 2,4,5-trichlorophenyl-β-D-glucopyranoside. These results, together with previously published results, suggest that conjugation with D-glucose is a stereotypic response of duckweed to challenge by phenol and chlorinated phenols.
A screening method for ranking and scoring chemicals by potential human health and environmental impacts
Authors: Swanson Mary B , Davis Gary A , Kincaid Lori E , Schultz Terry W , Bartmess John E , Jones Sheila L , George Emma Lou
Published: March 2010

Potential impacts of chemical releases are often evaluated by regulators, industry, and others to set regulatory action priorities, to make business decisions, and to target pollution prevention efforts. A chemical ranking and scoring method entitled “Chemical Hazard Evaluation for Management Strategies” (CHEMS-1) has been developed as a screening tool to provide a relative assessment of chemical hazards to human health and the environment. The purpose of this method is to place chemical release data into perspective by evaluating both the toxic effects of chemicals and the potential exposure to those chemicals. This is done by combining measures of chemical toxicity pertaining to both human health and the environment with chemical release amounts and information on environmental persistence and bioaccumulation. The CHEMS-1 was initially developed to select priority chemicals for assessing safer substitutes for major product and process uses, where chemicals were selected from Toxics Release Inventory (TRI) data and annual pesticide usage data. A two-tiered approach was adopted with CHEMS-1 presented here representing the first, or screening-level, tier.
Retention of imazaquin in soil
Authors: Regitano Jussara B , Bischoff Marianne , Lee Linda S , Reichert Jose Miguel , Turco Ronald F
Published: March 2010

The molecular complexity of imazaquin and presence of ionizable functional groups limits the ability to predict sorption behavior from single soil parameters such as organic carbon content. Partition coefficients (Kp) for both neutral and anionic forms of imazaquin as well as the effects of solution ionic strength and composition were investigated to more adequately describe sorption of imazaquin in soil. Soils representing a range of characteristics were evaluated, including soils with permanent negative or variable surface charge. Imazaquin retention resulted from combined sorption for the neutral (Kocn, 1,110 ± 80 L/kg) and anionic (Koc,a, 38 ± 20 L/kg) forms. Imazaquin sorption was best correlated to soil organic carbon content and soil-solution pH. However, results indicated that positively charged Fe2+ and Al3+ oxyhydroxides contribute to sorption of the organic anion; thus mineral surfaces contributed to sorption in soils with low organic carbon content. The effects of electrolyte matrices on imazaquin sorption were accounted for by concomitant changes in pH. However, enhanced imazaquin sorption was observed with increasing ionic strength for soils where pH-induced changes in speciation were negligible, indicating the role of mechanisms other than weak hydrophobic interactions. Addition of H2 PO −4 significantly decreased imazaquin sorption, especially in weathered soils.
Isolation and characterization of Microtox®-active components from aircraft de-icing/anti-icing fluids
Authors: Cancilla Devon A , Holtkamp Anke , Matassa Luca , Fang Xingchun
Published: March 2010

The goal of this project was to isolate and identify individual components from aircraft de-icing/anti-icing fluids (ADAs) through a toxicity-based bioassay analysis. A Microtox® bioassay fractionation scheme was used to isolate a number of active fractions from ADAFs. Active fractions were identified using multiple spectral techniques, including nuclear magnetic resonance, gas chromatography–mass spectrometry, liquid chromatography–mass spectrometry, and ultraviolet characterization. The primary Microtox-active fraction was shown to be a mixture of benzotriazole and tolyltriazoles, which are used as corrosion inhibitors in ADAF formulations. The identity of the compounds was confirmed through spectral and Microtox-toxicity analysis and comparison of commercially available standards.
Potential toxicity and aerobic biodegradability of sodium silicate chemical grout leachate
Authors: Malone J Michael , St. John Todd W , Barlaz Morton A , Borden Roy H
Published: March 2010

Large quantities of organic reagents are used in sodium silicate grouts for the stabilization of granular soils prior to construction projects. However, the fate and effects of these reagents in the subsurface are unknown. In this study, leachate from sodium silicate grouted soil specimens was tested for acute toxicity using Daphnia magna and Vibrio fisheri (Microtox®) assays. Additionally, a soil biometer test was used to measure the aerobic biodegradability of the grout leachate. Median lethal concentrations (LC50s) ranged from 1,220 to 3,260 mg/L as total organic carbon (TOC) for the D. magna test and from 4,500 to 22,180 mg/L as TOC for the Microtox test. More than 80% of the organics contained in the grout leachate were biologically converted to carbon dioxide in less than 30 d. The grout was found to be far less toxic than other common organic chemicals such as phenol.
Optimization of in situ bioassays withHyalella aztecaandChironomus tentans
Authors: Chappie Daniel J , Burton G Allen
Published: March 2010

Uncertainty is always associated with extrapolations of laboratory toxicity test responsesto in situ conditions. Exposing toxicity test organisms in situ reduces uncertainty by removing sampling related artifacts and better simulating natural exposures. The amphipod Hyalella azteca and the midge Chironomus tentans, were enclosed in plastic containers with 149- or 74-mm mesh openings. These chambers were anchored to stream substrates allowing continual water exchange and contact with sediments. Hyallela azteca survival was greater than 80% after 4 weeks of exposure. In situ testing with H. azteca in cold water (<15°C) resulted in survival consistently below 60%, possibly due to limited acclimation periods. Handling stress during laboratory to field transport reduced C. tentans survival. High survival was not consistently achieved until a protective ground paper towel substrate was used. A smaller mesh size (74 mm) on the chambers reduced the occurrence of indigenous organisms inside the chambers, making C. tentans identification unmistakable. In situ testing with C. tentans using refined methods resulted in greater than 80% survival after 2 weeks of exposure. In situ exposures of these two benthic invertebrates can effectively evaluate short- to long-term conditions of water and sediment quality.
Environmental assessment of a new food ingredient, the fat replacer olestra
Authors: Allgood Gregory S , McAvoy Drew C , Woltering Daniel M
Published: March 2010

Olestra is a new noncaloric food ingredient made from sugar and vegetable oil combined in such a way that it is not digested or absorbed. Olestra will be used to replace the cooking fat and oils used to make savory snacks such as potato chips. An environmental assessment (EA) was conducted to determine whether or not this consumer use of olestra would result in adverse impacts to the environment. The EA was also submitted to the U.S. Food and Drug Administration as part of the agency's review and approval process for this new food ingredient. To provide a conservative assessment, that is, to not underestimate potential environmental risk, exposure estimates were based on an upper-bound annual consumption value of 228 × 106 kg (about 500 million pounds) and the assumption that the entire amount would enter wastewater. The olestra environmental database is extensive and includes studies to address its fate and effects in wastewater treatment systems, sludge-amended soils, and receiving waters. Testing showed olestra was not toxic to aquatic organisms including bacteria, algae, zooplankton, and fish nor to terrestrial organisms including bacteria, plants, earthworms, and nine mammalian species. Testing also showed olestra will not bioconcentrate or persist. Aerobic biodegradation was demonstrated in both aquatic and terrestrial matrices and a plausible mineralization pathway was detailed that has application to both aerobic and anaerobic environments. Because of its very low water solubility (5–42 μg/L) and sorptive nature (Kd ranging from 10,000 to 287,000 L/kg), the vast majority of olestra that enters the environment will be associated with wastewater solids and sludges. Overall removal for primary and secondary treatment was 91 to 94%. Olestra was shown to be mineralized at a rate sufficient to prevent significant accumulation in soil even with annual reapplication of sludge (half-lives were 10–88 d depending upon the physical form [liquid or solid] of olestra). Laboratory and bench scale testing showed olestra did not adversely effect conventional wastewater treatment. Olestra exhibited no adverse effects on total suspended solids or chemical oxygen demand. Olestra's properties are compatible with disposal in landfills and by incineration. Olestra did not adversely impact full-scale septic tanks or physical properties of sludge-amended agricultural soils. Based on conservative exposure estimates and extensive testing, the evidence indicates that consumer use of olestra will not result in adverse effects on wastewater treatment or aquatic and terrestrial ecosystems.
Trichloroethylene and tetrachloroethylene reduction in a metallic iron–water-vapor batch system
Authors: Campbell Timothy J , Burris David R , Roberts A Lynn , Wells J Raymond
Published: March 2010

The reduction of trichloroethylene (TCE) and tetrachloroethylene (PCE) was examined in ananaerobic batch vapor–water system containing metallic iron. Concentrations of the parent compounds and products (some of which went on to react further) were determined at discrete time intervals during the reactions by analysis of the headspace vapor. cis-1,2-Dichloroethylene, 1,1-dichloroethylene, vinyl chloride, methane, chloroacetylene, acetylene, ethylene, ethane, and C3–5 alkenes and alkanes were observed as products from both compounds. Trichloroethylene was also observed from the reduction of PCE. The masses of unreacted polychlorinated ethylenes sorbed on the iron surface were significant based upon previously determined sorption isotherms, and were incorporated in carbon and chloride recovery estimates. Final carbon and chlorine recoveries of 76% and 104%, respectively, were obtained after a 92% loss of the initial TCE. After the loss of 74% of the initial PCE, the final carbon and chlorine recoveries were 90% and 118%, respectively. Reaction pathways, which include both hydrogenolysis and reductive β-elimination, are proposed to account for the observed products.
Fate and movement of endosulfan under field conditions
Authors: Antonious George F , Byers Matthew E
Published: March 2010

The impact of soil mulches on movement of endosulfan (Thiodan 3 EC) was measured under field conditions. Three soil treatments on a Lowell silty loam soil (5% organic matter) were used to reduce soil erosion and surface water runoff. Living turf mulch (tall fescue) between every cropping row (turf-1), turf every other row (turf-2), and no mulch (NM) treatments were compared. Thiodan was used as foliar single spray on tomato and pepper at the rate of 0.61 kg AI/ha. Following field spraying, runoff water, sediment, and soil samples were collected and analyzed for endosulfan concentration. Endosulfan infiltration through the vadose zone was monitored using pressure-vacuum lysimeters. Studies were also undertaken to determine the magnitude and dissipation of endosulfan stereoisomers (α- and β-endosulfan) and endosulfan sulfate. Analysis of samples was accomplished using gas chromatography (GC) and GC-coupled mass spectrometry (GC-MS). The results confirm the formation of endosulfan sulfate and its significance as a residue component in soil and also the relative persistence of the β-isomer as compared to the α-isomer. Cultivation of turf between cropping rows and pepper intercropped with tomato reduced runoff water and sediment loss and endosulfan movement from application site to surface water runoff. Treatments planted with pepper intercropped with tomato have a tremendous impact on reducing runoff water discharge (67.3% reduction) and sediment loss (85.9% reduction) compared to that planted with pepper plants only. Results indicated the vertical movement of endosulfan through the vadose zone at a concentration of 0.63 μg/L. Soil core data also indicated that endosulfan leached 23 to 46 cm in the soil.
Acute toxicity and aqueous solubility of some condensed thiophenes and their microbial metabolites
Authors: Seymour David T , Verbeek Allen G , Hrudey Steve E , Fedorak Phillip M
Published: March 2010

Petroleum or creosote contamination of surface waters, soils, or groundwaters introduces countless aromatic compounds to these environments. Among these are condensed thiophenes that were shown to be oxidized to sulfoxides, sulfones, and 2,3-diones by microbial cultures. In this study, the acute toxicities of 12 compounds (benzothiophene, benzothiophene sulfone, ben-zothiophene-2,3-dione, 3-, and 5-methylbenzothiophenes, 3-, and 5-methylbenzothiophene sulfones, 5-, and 7-methylbenzothio-phene-2,3-diones, dibenzothiophene, dibenzothiophene sulfoxide, and dibenzothiophene sulfone) were determined by the Microtox® and Daphnia magna bioassays. To aid in determining the toxicities, the solubilities of many of these compounds were determined, which showed that the oxidized compounds were much more water soluble than the parent thiophenes. In nearly every case, the oxidized compounds were less toxic than their parent thiophenes. The Microtox method was more sensitive than the D. magna bioassay, but in general, there was a good correlation between toxicities measured by the two tests. Samples were removed from batch cultures of a Pseudomonas strain capable of oxidizing the thiophenes, and these samples were subjected to Microtox bioassays. These experiments showed that the toxicities of the culture supernatants decreased with incubation time.
Altered locomotory behavior in woodlice (Oniscus asellus (L.)) collected at a polluted site
Authors: Sørensen Freddy F , Weeks Jason M , Baatrup Erik
Published: March 2010

The locomotory behavior of woodlice (Oniscus asellus (L.)) collected along a gradient of pollution from a plastics fire was quantified automatically for 4 h in the laboratory employing computer-aided video tracking. Six locomotory parameters were measured and the corresponding individual body metal concentrations determined. Additional woodlice were collected from the same site for total protein and glycogen analyses. Woodlice collected from the litter layer overlying a pyrolyzed plastic layer spent significantly less time in activity, resulting in a walked distance less than 50% of that of woodlice collected from a nearby reference location. Furthermore, a tendency to turn predominantly in either a left or a right direction and a tendency toward a higher discontinuity in moving was found for the woodlice collected on the pyrolyzed plastic. Overall, the aberrant behavior coincided with significantly elevated body concentrations of heavy metals and lowered protein and glycogen levels. The interference of metals with neurological and metabolic processes is discussed in relation to locomotion.
Genetic differentiation among laboratory populations of Hyalella azteca: Implications for toxicology
Authors: Duan Yihao , Guttman Sheldon I , Oris James T
Published: March 2010

Hyalella azteca of different origins are maintained in many laboratories and are extensively used in toxicological bioassays. Quality assurance of interlaboratory toxicity data can only be made when the amount of genetic differentiation among laboratory populations is known. We assayed genetic variability at 16 enzymatic loci in H. azteca stocks from six laboratories (2 U.S. Environmental Protection Agency [USEPA], 1 U.S. Fish and Wildlife Service [USFWS], University of Mississippi, Environment Canada, Burlington, ON, Canada, and New York Department of Environmental Conservation), as well as an additional species, Hyalella montezuma (used as an outgroup). Three divergent groups were identified in laboratory stocks of H. azteca based on both Nei's genetic identity and modified Rogers' genetic distance. These three groups were differentiated genetically at a level characteristic of distinct species (Nei's I = 0.26–0.69) based on the comparison between H. azteca and H. montezuma. The high level of genetic differentiation among populations indicated that the Burlington and New York populations were distinct species of Hyalella. In order to enhance interlaboratory toxicity test comparisons, we recommend using genetically characterized populations of H. azteca.
Acute toxicity and behavioral effects of chlorpyrifos, permethrin, phenol, strychnine, and 2,4-dinitrophenol to 30-day-old Japanese medaka (Oryzias latipes)
Authors: Rice Patricia J , Drewes Charles D , Klubertanz Theresa M , Bradbury Steven P , Coats Joel R
Published: March 2010

Five chemicals with different modes of action were evaluated in laboratory studies to determine their acute toxicity (48-h median lethal concentration [LC50]) and behavioral effects on 30-d-old Japanese medaka (Oryzias latipes). The order of toxicity for these xenobiotics was permethrin > chlorpyrifos > 2,4-dinitrophenol (2,4-DNP) > strychnine > phenol. The 48-h LC50s were significantly different and ranged from 0.011 to 24.1 mg/L. In addition, chlorpyrifos and permethrin accumulated in the tissues of juvenile O. latipes. Observations of five behavioral/morphological responses, including changes in equilibrium, general activity, startle response, and morphology (e.g., hemorrhage and deformities) were used as indicators of sublethal toxicity. Each chemical, with the exception of 2,4-DNP, elicited a distinct behavior or set of behavioral responses. The behavioral toxicology bioassay may be valuable in comparing and predicting the mode of action of new or unknown toxicants in this species of fish.
Resistance to malathion in heat-shocked Daphnia magna
Authors: Bond Jayne-Anne , Bradley Brian P
Published: March 2010

A 34°C heat shock has been shown to induce a transient tolerance to malathion in the cladoceran Daphnia magna. HSP70, a common heat-shock protein, is induced by the same heat shock. Various possible mechanisms exist to explain this heatinducible response. Several enzyme systems are known to be involved in the detoxification of pesticides, including the esterases, transferases, and oxidases. Changes in general esterase, carboxylesterase (Ali esterase, AliE), and glutathione- S-transferase (GST) activities were examined as mechanisms to explain this phenomenon. General esterase activity was not affected by a 34°C heat shock, but was reduced to nearly zero in lethal malathion concentrations, with or without heat shock. Conversely, although AliE activity was reduced by heat shock, there was no further effect of malathion on AliE in either the heat-shocked or control animals. A heatinducible high molecular mass protein complex with GST activity was observed in the resistant daphnids. There was no corresponding increase in GST activity, however. These data suggest that the transient protection against malathion is not caused by an increase in the amount of enzyme or enzyme activity.
Polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in fishes from Saginaw Bay, Michigan
Authors: Giesy John P , Jude David J , Tillitt Donald E , Gale Robert W , Meadows John C , Zajieck James L , Peterman Paul H , Verbrugge David A , Sanderson J Thomas , Schwartz Ted R , Tuchman Marc L
Published: March 2010

Concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated naphthalenes (PCNs), polychlorinated dibenzothiophenes (PCDTs), and 2,3,7,8-tetrachlo-rodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents were measured in composite samples of forage fishes and several sizes of walleyes (Stizostedion vitreum) and common carp (Cyprinus carpio) collected from Saginaw Bay, Michigan, USA. The concentrations of 2,3,7,8-TCDD equivalents determined from the use of TCDD equivalency factors (TEFs) and instrumentally determined concentrations of individual congeners were designated TEq. The 2,3,7,8-TCDD equivalents determined on the same extracts with the H4IIE bioassay were defined as TCDD-EQ. Concentrations of TCDD-EQ and TEq were significantly, but poorly correlated (R2 = 0.44). Concentrations of TCDD-EQ and TEq ranged from 10.6 to 348 and 13.5 to 69.5 ng/kg, wet weight, respectively. The ratio of TCDD-EQ to TEq ranged from 0.5 to 5.0, with the greatest ratio observed in common carp but the average ratio between TEq and TCDD-EQ was approximately 1.0. In common carp, larger walleye, and medium-sized alewife (Alosa pseudoharengus) there were significant concentrations of TCDD-EQ that could not be accounted for by TEq calculated from an additive model of PCBs, PCDDs, or PCDFs. As much as 75% of the TCDD-EQ in some samples could not be accounted for by TEqs. It is unlikely that PCNs, PCDTs, or polychlorinated diphenyl ethers (PCDEs) occurred at concentrations that were, based on their relative potencies, great enough to contribute significant quantities of TCDD-EQ. The discrepency between TCDD-EQs and TEqs was not due to antagonisms among congeners or extraction efficiencies.
Heavy metal accumulation in sediment and freshwater fish in U.S. Arctic lakes
Authors: Allen-Gil Susan M , Gubala Chad P , Landers Dixon H , Lasorsa Brenda K , Crecelius Eric A , Curtis Lawrence R
Published: March 2010

Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus]) were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated lakes in other Arctic regions and more temperate locations. For example, concentrations of Hg and Ni were 175 ng/g and 250 ng/g dry weight, respectively, in Feniak Lake surface sediment. If any anthropogenic enrichment has occurred, it is not distinguishable from background variability based on surface sediment to down core comparisons. With the exception of Hg, the site rank order of metal concentrations (Cu, Cd, Ni, Pb, and Zn) in sediment and freshwater fish tissue among lakes is not consistent. This suggests that a number of physical, chemical, and physiological parameters mediate metal bioavailability and uptake in these systems. Maximum concentrations of most metals in fish from this study are equal to or higher than those collected from remote Arctic lakes and rivers in Canada, Finland, and Russia. Muscle Hg concentrations in excess of 1 μg/g wet weight were observed in lake trout from Feniak Lake, which has no identified Hg source other than naturally Hg-enriched sediments. Fish diet seems to influence some heavy metal burdens, as evidenced by the higher concentrations of some metals in lake trout compared to grayling, and differences among lakes for lake trout. Cadmium, Cu, and Zn burdens were higher in lakes where snails were consumed by trout compared to lakes without snails.
Accumulation and toxicokinetics of fluoranthene in water-only exposures with freshwater amphipods
Authors: Driscoll Susan Kane , Landrum Peter F , Tigue Elizabeth
Published: March 2010

Two 10-d water-only toxicity tests with radiolabeled fluoranthene were conducted with two species of freshwater amphipods, Hyalella azteca and Diporeia sp. For H. azteca, 10-d median lethal concentrations were 564 nmol/L and 481 nmol/L. Tentative median lethal doses, determined from the regressions of body burden of remaining live H. azteca versus survival, were 5.6 and 3.6 mmol fluoranthene/kg wet weight tissue. Diporeia appeared to be less sensitive, because survival in Diporeia was greater than 84% after 10-d exposures. Elimination rates determined for Diporeia, ranging from 0.0011 to 0.0042/h (half-lives of 7–26 d), were much slower than rates determined for H. azteca of 0.128 to 0.188/h (half-lives of 4–6 h). Faster elimination in H. azteca may be related to its greater ability to metabolize fluoranthene. For H. azteca, an average of 17% of its body burden was present as metabolites after 24 h of exposure to radiolabeled fluoranthene, as compared to 5% for Diporeia. For Diporeia, exposure to various water concentrations of fluoranthene for various lengths of time resulted in declines in the conditional uptake clearance rates (ml water cleared/g wet weight tissue/h). A similar, although less dramatic trend was observed for conditional uptake clearance rates in H. azteca.
Effects of alachlor on an algal community from a midwestern agricultural stream
Authors: Spawn Rebecca L , Hoagland Kyle D , Siegfried Blair D
Published: March 2010

The effects of a single pulse, 21-d exposure of the commonly used herbici de a achlor (2-chloro-2′, 6′-diethyl-N-methoxymethyl acetanilide) on an algal community from a typical agricultural stream in Nebraska were studied using 18 stream microcosms located in a greenhouse, at six alachlor concentrations (0, 1, 10, 30, 100, and 1,000 μg/L). Effects of alachlor exposure at 1.0 μg/L were not significant (p < 0.05); however, at all other concentrations, alachlor had a significant negative effect on algal biomass. Differential taxonomic responses were observed, with approximately half the dominant algal taxa affected at levels >10 μg/L. Some taxa recovered from exposure by day 7, while others took longer or did not recover. A shift in the dominant algae was observed at higher concentrations (30, 100, 1,000 μg/L), and after 21 d these streams exhibited total algal cell densities significantly lower than the control and 1.0-μg/L-level streams. Results of this study suggest that alachlor inputs can alter both algal community composition and biomass in agricultural streams. Consequently, potential indirect impacts of alachlor on higher trophic levels warrant further investigation.
Study of heavy metals and other elements in macrophyte algae using energy-dispersive x-ray fluorescence
Authors: Carvalho Maria L , Ferreira Joao, G , Amorim Pedro , Marques Maria I M , Ramos Maria T
Published: March 2010

Fucus vesiculosus L. seaweeds from three estuarine stations were analyzed by X-ray fluorescence, providing results for the concentration of total K, Ca, Ti, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Sr, and Pb. Four different structures of the algae (base, stipe, reproductive organs, and growing tips) were analyzed to study the differential accumulation of heavy metals by different parts of Fucus. Some elements (e.g., Cu and Fe) are preferentially accumulated in the base of the algae, whereas others (e.g., As) exhibit higher concentrations in the reproductive organs and growing tips. The pattern of accumulation in different structures is similar for Cu, Zn, and Pb, but for other metals there is considerable variability in accumulation between parts of the plant. This is important in determining which structures of the plant should be used for biomonitoring. For samples collected at stations subject to differing metal loads, the relative elemental composition is approximately constant, notwithstanding significant variation in absolute values. The proportion of metals in Fucus is similar to that found in other estuaries, where metal concentrations are significantly lower. Energy-dispersive X-ray fluorescence has been shown to be a suitable technique for multielement analysis in this type of sample. No chemical pretreatment is required, minimizing sample contamination. The small amount of sample required, and the wide range of elements that can be detected simultaneously make energy-dispersive X-ray fluorescence a valuable tool for pollution studies.
Effect of acclimation period on the relationship of acute copper toxicity to water hardness for fathead minnows
Authors: Erickson Russell J , Kleiner Charles F , Fiandt James T , Highland Terry L
Published: March 2010

The acute (96-h) toxicity of copper sulfate to fathead minnows was tested in a 2 × 2 factorial experiment, with factors being low (ca. 1 meq/L) and high (ca. 4 meq/L) water hardness during an acclimation period and low and high hardness during the exposure period. Acclimation hardness was found to have no significant effects on copper lethality, except that the 24-h LC50 at high exposure hardness was 44% higher for fish subject to low acclimation hardness than fish subject to high acclimation hardness. In contrast, exposure hardness was found to have major effects, with LC50s being two to three times greater at high exposure hardness than at low, regardless of the acclimation hardness. These results suggest that the extent of the acclimation period is not a general, severely confounding factor for previous reports of the effects of hardness on copper toxicity to fish, although it may assume some importance for some species and test conditions.
Comparative metabolism of benzo[a]pyrene by liver microsomes of channel catfish and brown bullhead
Authors: Yuan Zhi-Xin , Kumar Subodh , Sikka Harish C
Published: March 2010

We investigated the metabolism of the carcinogen benzo[a]pyrene (BaP) by liver microsomes of channel catfish (Ictalurus punctatus) and brown bullhead (Ameiurus nebulosus) pretreated with 3-methylcholanthrene. The catfish liver microsomes metabolized BaP at a considerably lower rate than did the brown bullhead liver microsomes. Although the BaP metabolites produced by the liver microsomes of the two species were qualitatively similiar, there were considerable differences in the relative proportions of individual metabolites formed. The catfish liver microsomes produced a considerably lower proportion of benzo-ring diols of BaP including BaP-7,8-diol (the proximate carcinogenic metabolite of BaP) than did the bullhead liver microsomes. Compared to the bullhead liver microsomes, the catfish microsomes converted a higher proportion of BaP to phenolic metabolites.
Inhibitory effects of 2-mercaptobenzothiazole on microbial growth in a variety of trophic conditions
Authors: De Wever Helene , Van den Neste Saskia , Verachtert Hubert
Published: March 2010

2-Mercaptobenzothiazole (MBT) is found mainly in the wastewaters of its industrial production as a rubber vulcanization accelerator. Because this compound was found to be toxic to activated sludges and because it causes poor process performances, its impact on bacteria in particular was studied. 2-Mercaptobenzothiazole, but not other benzothiazoles, exerted mainly bacteriostatic effects towards Escherichia coli, Sarcina lutea, Staphylococcus aureus, and a 2-hydroxybenzothiazole-degrading isolate (OBT18). It caused membrane disturbance as measured by induced potassium effluxes from the cell. Emphasis was on the effects of MBT on growth of E. coli on different electron donor-electron acceptor combinations. Paracoccus denitrificans was grown in the presence of oxygen or nitrate and the yeast Saccharomyces cerevisiae was used under aerobic and fermentative conditions. In almost all conditions the growth was severely inhibited, indicating that MBT might interfere with a common oxidoreduction step in membrane-bound systems and probably also interferes with metabolic reactions not related to the respiratory chain.
Toxicity of a pah photooxidation product to the bacteria Photobacterium phosphoreum and the duckweed Lemna gibba: Effects of phenanthrene and its primary photoproduct, phenanthrenequinone
Authors: McConkey Brendan J , Duxbury Cheryl L , Dixon D George , Greenberg Bruce M
Published: March 2010

Phenanthrene (PHE) undergoes a significant increase in toxicity after exposure to simulated or natural sunlight in aqueous media, coincident with the appearance of PHE photoproducts. To investigate whether the primary photoproduct of PHE, 9,10-phenanthrenequinone (PHEQ), contributes to the increased hazards of solutions containing photomodified PHE, toxicity assays were conducted using the marine bacteria Photobacterium phosphoreum and the aquatic plant Lemna gibba (duckweed). Photo-bacterium phosphoreum was exposed to PHE, PHEQ, a photomodified PHE mixture containing known amounts of PHE and PHEQ (pmPHE), and a mixture mimicking the amounts of PHE and PHEQ in the pmPHE mixture. The bacteria were found to be equally sensitive to PHE in simulated solar radiation (SSR, a light source with a visible light : UVA : UVB ratio similar to that of sunlight) or darkness, with an EC50 of 0.53 mg/L. In both darkness or SSR, solutions containing PHEQ (with or without PHE) all exhibited an EC50 of 0.06 to 0.10 mg/L based on PHEQ concentrations, indicating that PHEQ was the primary active component of the pmPHE mixture. Lemna gibba was tested in SSR and visible light with PHE, PHEQ, and the pmPHE mixture. The calculated EC50 for PHE was 3.5 mg/L in SSR and 10.8 mg/L in visible light, showing that the presence of UV radiation in the SSR source increased the phytotoxicity of PHE. Strikingly, PHEQ was much more toxic to L. gibba than PHE in a light-independent manner (an EC50 of 0.53 and 0.57 mg/L PHEQ in dark and SSR, respectively). Thus, for both P. phosphoreum and L. gibba the major photooxidation product of PHE in SSR, PHEQ, is the more toxic of the two chemicals.
Methyl mercury toxicokinetics in channel catfish (Ictalurus punctatus) and largemouth bass (Micropterus salmoides) after intravascular administration
Authors: Schultz Irvin R , Newman Michael C
Published: March 2010

We compared the differences in the distribution and elimination of CH3Hg after intraarterial injection and serial blood removal in catfish and bass of similar body size under consistent water quality conditions. The blood and plasma concentration-time profiles of individual fish were analyzed using a three-compartment, clearance-volume model. The plasma protein binding of CH3Hg was determined by ultrafiltration (30,000 mol. wt. cutoff) and the binding affinity (ρ) of CH3Hg for red blood cells (RBCs) was also calculated. Toxicokinetic analysis of the plasma concentration-time profiles provided the following values: apparent volume of distribution at steady state (Vss) = 30 ± 14 ml/g (catfish), 6.2 ± 2 ml/g (bass); total body clearance (Clb) = 0.026 ± 0.011 ml/h/g (catfish), 0.0057 ± 0.001 ml/h/g (bass). The values of Vss and Clb estimated from the blood concentration-time profiles in catfish and bass were fivefold lower. The elimination half-life from blood and plasma was between 814 and 1670 h and was not statistically different between species or reference fluid. The AUC0→∞ for blood was over three times higher than plasma, due to the binding of CH3Hg to RBCs. The unbound fraction of CH3Hg in bass plasma was 14-fold lower (0.25 vs. 3.64%) and the ρ for RBCs was 20 times greater than catfish (5,974 vs. 289). The decreased binding to plasma and RBCs in catfish is consistent with the increased extravascular distribution and clearance capacity of CH3Hg in catfish because a larger fraction of the CH3Hg in blood is available to distribute outside the vascular system.
Effects of surfactants on the rotifer,Brachionus calyciflorus, in a chronic toxicity test and in the development of qsars
Authors: Versteeg Donald J , Stanton David T , Pence Michael A , Cowan Christina
Published: March 2010

The toxicity of a range of surfactant and surfactant-related compounds was investigated in the 2-d whole life cycle bioassay with the rotifer, Brachionus calyciflorus. Compounds were selected to gain an understanding of how structural components, especially the polar head groups, contribute to toxicity. Rotifers were exposed under static test conditions to the 22 compounds for 2d. Exposure concentrations were verified analytically in the test system. Results demonstrate a relationship between alkyl chain length and toxicity within a surfactant class. Between classes, N-containing amines and quaternary ammonium compounds had greatest toxicity, in general, followed by the nonionic compounds. Anionic compounds were typically least toxic. A good quality (R2 = 0.86), three-variable, parametric QSAR model was developed using the ADAPT software package. The model contains one variable to account for the contribution of the hydrophobic tail group to observed toxicity (the number of sp3-hybridized carbons bonded to two other carbons [2SP3]) and two descriptors, the valence-corrected, fourth-order cluster index (4XvC) and a count of the number of nitrogens in the molecule (NN), to account for the contribution of the polar head group.
Cryopreservation of fluorescent marker-labeled algae (Selenastrum capricornutum) for toxicity testing using flow cytometry
Authors: Faber Marvin J , Smith Lisa M J , Boermans Herman J , Stephenson Gerald R , Thompson Dean G , Solomon Keith R
Published: March 2010

A rapid, two-stain (fluorescein diacetate and ethidium homodimer-1) flow cytometric assay to evaluat viability and cytotoxicity of the alga Selenastrum capricornutum in preserved samples is described. For storage, stained cells were fixed in glutaraldehyde, flash frozen in liquid nitrogen, and stored frozen (−20°C) for assessment at a later date. Weekly analysis of frozen samples showed that fluorescence was stable for 7 weeks. A mixture of 50% healthy and 50% heat-killed cells of S. capricornutum showed 36.1% healthy cells, 13.2% compromised cells, 12% nonstained cells, and 38.7% dead cells. This technique was tested using sodium dodecyl sulfate (SDS) and phenol as toxicants. Threshold concentrations for toxicant impact were in the range of 1 to 10 mg/L for SDS and 10 to 100 mg/L for phenol. Estimates of mortality showed 96-h median lethal concentration (LC50) values of 2,340 mg/L and 6,970 mg/L for SDS and phenol, respectively. This two-stain flow cytometric procedure has proven to be a reliable, sensitive assay for determining viability of S. capricornutum in preserved samples. The sensitivity of this dual-color assay and the ability to store samples for later analysis are significant improvements over current techniques.
Bacterial inoculants of forage grasses that enhance degradation of 2-chlorobenzoic acid in soil
Authors: Siciliano Steven D , Germida James J
Published: March 2010

Biological remediation of contaminated soil is an effective method of reducing risk to human and ecosystem health. Bacteria and plants might be used to enhance remediation of soil pollutants in situ. This study assessed the potential of bacteria (12 isolates), plants (16 forage grasses), and plant-bacteria associations (selected pairings) to remediate 2-chlorobenzoic acid (2CBA)-contaminated soil. Initially, grass viability was assessed in 2CBA-contaminated soil. Soil was contaminated with 2CBA, forage grasses were grown under growth chamber conditions for 42 or 60 d, and the 2CBA concentration in soil was determined by gas chromatography. Only five of 16 forage grasses grew in 2CBA-treated (816 mg/kg) soil. Growth of Bromus inermis had no effect on 2CBA concentration, whereas Agropyron intermedium, B. biebersteinii, A. riparum, and Elymus dauricus decreased 2CBA relative to nonplanted control soil by 32 to 42%. The 12 bacteria isolates were screened for their ability to promote the germination of the five grasses in 2CBA-contaminated soil. Inoculation of A. riparum with Pseudomonas aeruginosa strain R75, a proven plant growth-promoting rhizobacterium, increased seed germination by 80% and disappearance of 2CBA by 20% relative to noninoculated plants. Inoculation of E. dauricus with a mixture of P. savastanoi strain CB35, a 2CBA-degrading bacterium, and P. aeruginosa strain R75 increased disappearance of 2CBA by 112% relative to noninoculated plants. No clear relationship between enhanced 2CBA disappearance and increased plant biomass was found. These results suggest that specific plant-microbial systems can be developed to enhance remediation of pollutants in soil.