bluuebunny/crossref_metadata_2025 huggingface dataset:
Fate and effects of the herbicide atrazine in flow-through wetland mesocosms
Authors: Detenbeck Naomi E. , Hermanutz Roger , Allen Kathleen , Swift Michael C.
Published: March 2010

Wetland mesocosms were exposed to increasing concentrations of atrazine over time at levels typical of midwestern surface waters following spring runoff (15 to 75 μg/L). Atrazine had a half-life of 8 to 14 d in the 230-m-long wetlands. End points measured included nutrient levels; periphyton biomass; periphyton productivity and respiration; growth of selected macrophytes; and survival and growth of Daphnia magna (15, 25 μg/L atrazine), Rana pipiens (15, 25 μg/L), and Pimephales promelas larvae (25 to 75 μg/L) and adults (50, 75 μg/L). Interaction between nutrient status or grazing intensity and atrazine effects were measured using periphyton enrichment and grazing exclosure experiments. Only periphyton, Ceratophyllum demersum, Zizania aquatica, and Daphnia were significantly affected by atrazine at any of the concentrations tested. Periphyton net productivity was significantly depressed by incubation in treated water as compared to control water at ≥25 μg/L atrazine (9 to 27-d exposures). In response, dissolved nutrient concentrations increased in treated mesocosms after 14 d. Ceratophyllum length/weight ratios increased after 6-d exposures to 50 μg/L atrazine, while Zizania senesced prematurely during treatments of 50 or 75 μg/L atrazine (97 d of cumulative exposure). Periphyton developed resistance to atrazine only at concentrations ≥50 μg/L. Atrazine effects on periphyton composition varied with the N:P supply ratio. Daphnia survival was significantly depressed at 15 μg/L atrazine (48-h exposures).
Multivariate modeling of pcb bioaccumulation in three-spined stickleback (Gasterosteus aculeatus)
Authors: VanBavel Bert , Andersson Patrik , Wingfors Hakan , Rappe Christoffer , Tysklind Mats , Bergqvist Per-Anders , Ahgren Jorgen , Norrgren Leif
Published: March 2010

Three-spined sticklebacks were exposed to 20 polychlorinated biphenyls (PCBs) through gastrointestinal intake. The PCBs, viz. 2,2′,3,4- TeCB, 2,2′,4,6′-TeCB, 2,3,3′,5′-TeCB, 2,3,4,4′-TeCB, 2,3′,4,5′- TeCB, 3,3′,4,5-TeCB, 2,2′,3,4′,6-PeCB, 2,2′,4,4′,5-PeCB, 2,2′,4,6,6′-PeCB, 2,3,3′,5,6-PeCB, 2,3,4,4′,6-PeCB, 3,3′4,4′,5- PeCB, 2,2′,3,4,5,6′-HxCB, 2,2′,4,4′,5,5′-HxCB, 3,3′,4,4′,5,5′-HxCB, 2,2′,3,3′,4,5,6-HpCB, 2,2′,3,4,4′,6,6′-HpCB, 2,2′,3,4′,5,6,6′-HpCB, 2,3,3′,4,4′,5,6-HpCB, and 2,3,3′,4′,5,5′,6-HpCB, were selected by means of a full factorial design in combination with principal component analyses based on several physicochemical properties of tetra- through hepta-PCBs. After exposure to the training set, pooled samples of the sticklebacks were analyzed by GC-MS after lipid determination and cleanup using Florisil open-column chromatography. Bioaccumulation factors (BAFs) were calculated on a lipid basis by dividing the PCB concentrations in the fish by the respective concentrations in the feed. Higher chlorinated PCBs showed, in general, higher bioaccumulation than the lower chlorinated congeners. Polychlorinated biphenyls with vicinal hydrogens in the meta- and para-positions exhibited low bioaccumulation. Finally 18 of the 20 measured BAFs were used to calculate a multivariate quantitative structure–activity relationship (QSAR) by means of partial least squares fitting to latent structures. By applying this QSAR, the bioaccumulation potentials of 136 nontested tetra- through hepta-PCB congeners were predicted.
Mixed-function oxidase enzyme activity and oxidative stress in lake trout (Salvelinus namaycush) exposed to 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126)
Authors: Palace Vince P. , Klaverkamp Jack F. , Lockhart W. Lyle , Klaverkamp Jack F. , Lockhart W. Lyle , Metner Don A. , Muir Derek C. G. , Brown Scott B.
Published: March 2010

Juvenile lake trout were intraperitoneally injected with corn oil containing nominal concentrations of 0, 0.6, 6.3, or 25 μg [14C]-3,3′,4,4′,5-pentachlorobiphenyl (PCB-126) per gram of body weight. The PCB-126 accumulated in liver in a dose-dependent manner to a sustained concentration by 6 weeks and remained elevated for the 30-week experimental period. Mixed-function oxidase (MFO) enzyme activity was elevated in the two highest dose groups relative to the control group, but not in the low-dose group throughout the 30 weeks. Oxidative stress, measured by the thiobarbituric acid reactive substances test, was correlated with ethoxyresorufin O-deethylase and was elevated in liver of the two highest PCB dose groups but not the low-dose group. The activities of the enzymatic antioxidants superoxide dismutase, catalase, and glutathione peroxidase were unaffected by PCB-126 exposure. The nonenzymatic antioxidant tocopherol was depleted to approximately 75% of the control concentration in liver of all three PCB-dosed groups. Hepatic ascorbic acid levels were not different in any of the treatment groups. Retinol was depleted by greater than an order of magnitude in liver of the two highest dose groups but not in the low-dose group. This study demonstrates a correlation between hepatic MFO activity and oxidative stress in PCB-exposed lake trout. Tocopherol and retinol may be important mediators of oxidative stress but additional study is required to confirm the antioxidant activity of retinol.
Use of rodeo® and X-77® spreader to control smooth cordgrass (Spartina alterniflora) in a southwestern washington estuary: 2. Effects on benthic microflora and invertebrates
Authors: Simenstad Charles A. , Cordell Jeffery R. , Tear Lucinda , Weitkamp Laurie A. , Paveglio Fred L. , Kilbride Kevin M. , Fresh Kurt L. , Grue Christian E.
Published: March 2010

In August 1992, we conducted an intensive short-term (within 119d)experiment in southern Willapa Bay, Washington, to evaluate the potential effects on mudflat benthic communities of herbicide control of smooth cordgrass, Spartina alterniflora Loisel. A mixture of glyphosate (Rodeo®; 4.7 L ha−1) and an associated surfactant, alkylarylpolyoxyethylene (AAPOE, X-77® Spreader; 1 L ha−1) was applied aerially to three mudflat sites with invasive S. alterniflora. Sediment structure (grain size), edaphic microalgal biomass (chlorophyll a), and densities of benthic and epibenthic meiofauna and benthic macrofauna were sampled systematically in treated and adjacent control (untreated) plots 1 d before, immediately after, and 1, 14, 28 and 119 d after spraying. These mudflat biota showed no definitive differences in population trends that would indicate acute responses to the herbicide and surfactant applications over the 119-d duration of the experiment. Two-way ANOVA tests of differences in slope of linear regressions of mean plot microalgal biomass and invertebrate density of 19 taxa groups or species testing short-term (2 weeks) and long-term (17 weeks) trends in response to the experimental treatment tests indicated no significant (p < 0.1) treatment and only three site effects. Natural variability in the standing stocks (in the case of benthic microalgae) or densities (invertebrates) of most of the 19 indicator taxa prior to spray application was sufficiently high within and between treatment and control plots and among sites to preclude strong inferential tests of acute effects. Although differences in mudflat habitats (e.g., tidal elevation, sediment structure) inherent in the sites prior to treatment affect the power of our ability to test direct effects, there were no indications of either short- or long-term effects on the mudflat community of aerially applying this concentration of herbicide and surfactant. This study did not explicitly address either sublethal or indirect ecological effects, such as associated with an observed decrease in the exotic eelgrass Zostera japonica, which might appear as a longer-term, more subtle response by the mudflat community.
Biogeochemical interactions affecting hepatic trace element levels in aquatic birds
Authors: Möller Gregory
Published: March 2010

Knowledge of elemental interactions is important to the toxicological assessment of wildlife in the geochemical environment. This study determines the concentrations of Al, As, B, Ba, Be, Cd, Cr, Cu, Fe, Pb, Li, Mg, Mn, Hg, Mo, Ni, Se, Ag, V, and Zn in aquatic bird liver, fish liver, whole bivalves, insects, and waters in several aquatic ecosystems in northern California. There is evidence of strong in vivo and environmental interactions, including the observation of manganese as a possible cofactor or indicator in selenium bioaccumulation. The nearest neighbor selenium correlation in aquatic bird liver tissue that results from this work is Cd–Mn–Se–Hg–As. The correlation of liver selenium to manganese in vivo and the result that the majority of the variance in liver selenium concentration is contained in the manganese term of the regression model relating Se to Cd, Mn, and Hg is new knowledge in the study of aquatic birds. A linear relationship between liver selenium and environmental manganese (water and sediment) is found in the data, suggesting a water chemistry compartmentalization or activation of toxicants. Alternatively, the hepatic concentrations of selenium, manganese, and iron suggest induction of enzymes in response to oxidative stress.
Effect of cadmium on reductive dechlorination of trichloroaniline
Authors: Pardue John H. , Kongara Selvi , Jones Jack W.
Published: March 2010

The effect of a transition metal, cadmium (Cd), on reductive dechlorination of a model chlorinated organic, 2,3,4-trichloroaniline (2,3,4-TCA), was determined in the laboratory in three anaerobic, flooded soils with varying properties. Dechlorination of 2,3,4-TCA was inhibited over a continuum of pore-water-soluble Cd concentrations (10–200 μg/L) in mineral-dominated rice paddy and bottomland hardwood soils. In organic-dominated marsh soil, however, a critical inhibitory level of pore-water-soluble Cd (200 μg/L) was observed. Lower-chlorinated aniline metabolites differed with soluble Cd concentration. Different metabolites (2,3-dichloroaniline and 2-chloroaniline) were observed in some soils as Cd neared the completely inhibitory concentration. Speciation of soluble Cd was necessary to predict whether inhibition would occur, particularly in the presence of high concentrations of organic ligands such as humic acids. Selective extractions and measurement of acid-volatile sulfides provided additional information but did not adequately predict inhibition of dechlorination. These results demonstrate the importance of quantification and speciation of pore-water metal concentrations in predicting potential inhibition of anaerobic biodegradation reactions such as reductive dechlorination.
Predicting soil sorption coefficients of organic chemicals using a neural network model
Authors: Gao Chao , Govind Rakesh , Tabak Henry H.
Published: March 2010

The soil/sediment adsorption partition coefficient normalized to organic carbon (Koc) is extensively used to assess the fate of organic chemicals in hazardous waste sites. Several attempts have been made to estimate the value of Koc from chemical structure or its parameters. The primary purpose of this study was to develop a nonlinear model for estimating Koc applicable to polar and nonpolar organics based on artificial neural networks using the octanol/water partition coefficient (Kow) and water solubility (S). An analytic equation was obtained by starting with a neural network, converging the bias and weight values using the available data on water solubility, octanol/water partition coefficient, and the normalized soil/sediment adsorption partition coefficient, and then combining the equations for each node in the final neural network. For the 119 chemicals in the training set, estimates using the neural network equation lie outside the 2σ region (the standard deviation for the training set, σ = 0.52) for only five chemicals, while all the chemicals in the test set lie within the 2σ region. It was concluded that the neural network equation outperforms the linear models in fitting the Koc values for the training set and predicting them for the test set.
Studies on the effects of the herbicide simazine on microflora of four agricultural soils
Authors: Martinez-Toledo Maria Victoria , Salmeron Victoriano , Rodelas Belen , Pozo Clementina , Gonzalez-Lopez Jesus
Published: March 2010

The effects of 10, 50, 100, 200, and 300 μg simazine per gram of soil was studied under aerobic conditions. Compared with control soil, the herbicide simazine did not affect bacterial populations, fungi, aerobic dinitrogen-fixing bacteria, denitrifying bacteria, and nitrogenase activity. However, nitrifying bacteria were decreased at concentrations of 50 to 300 μg/g. The negative effects observed on nitrifying bacteria in soil amended with simazine were particularly evident after a second application of herbicide, showing that these microorganisms cannot tolerate certain concentrations of simazine.
Quantitation of dose-dependent increases in CYP1A1 messenger RNA levels in juvenile chinook salmon exposed to treated bleached-kraft mill effluent using two field sampling techniques
Authors: Campbell Pamela M. , Kruzynski George M. , Birtwell Ian K. , Devlin Robert H.
Published: March 2010

Increases in hepatic CYP1A1 messenger RNA (mRNA) levels were quantitated, using a reverse-transcriptase–competitive-polymerase-chain-reaction assay, from juvenile chinook salmon following exposure to treated bleached-kraft mill effluent (BKME). Two tissue preservation techniques, alcohol fixation and freezing, were compared and both found to be valid, although absolute values obtained differed between the methods. The results of this study show that juvenile chinook respond with a dose-dependent induction of CYP1A1 mRNA to levels of treated BKME found under winter, low-flow conditions downstream of pulp mills in the Fraser River, British Columbia, Canada. The validation of alcohol fixation as a sampling technique for studies on mRNA levels improves the ease of field sampling and increases the feasibility of using CYP1A1 mRNA level as a bioindicator of exposure of fish to specific chemical contaminants.
Effects of the insecticide dursban® 4E (active ingredient chlorpyrifos) in outdoor experimental ditches: I. Comparison of short-term toxicity between the laboratory and the field
Authors: van Wijngaarden René P. A. , van den Brink Paul J. , Crum Steven J. H. , Brock Theo C. M. , Leeuwangh Peter , Voshaar Oude Jan H.
Published: March 2010

Using the insecticide Dursban ® 4E (active ingredient chlorpyrifos) as the test compound, results of laboratory acute single-species toxicity tests with indigenous and standard test species were compared with short-term direct effects in outdoor experimental ditches (mesocosms). In the mesocosms a regression experiment was performed with nominal initial chlorpyrifos concentrations of 0.1, 0.9, 6, and 44 μg/L. The mesocosms were sprayed once. Effects were investigated by sampling macroinvertebrates and zooplankton and by doing in situ cage experiments with several species. Chlorpyrifos concentrations showed highest spatial and temporal variation within 2 d of treatment. Acute effects were observed on arthropods only and essentially were manifest on day 0. Short-term direct effects in the mesocosms could be quantified by a regression method for seven of 120 species. For these species, 48- and 96-h median effective concentrations (EC50s) ranged from 0.1 to 3.4 μg/L and were in the same order of magnitude as their laboratory EC50s. Susceptibility of the most sensitive standard test species (Daphnia magna; 48-h median lethal concentration [LC50], 1 μg/L) was more or less representative of susceptible indigenous species. In the mesocosms effects were negligible at the 0.1-μg/L treatment level. A safety factor of 0.1 (48-h LC50 of Daphnia magna) may have protected almost all of the species in the community in the mesocosms against short-term direct effects. A safety factor of 0.01 probably protected the most susceptible taxa we found (laboratory 96-h EC10 for Gammarus pulex, 0.02 μg/L; no-observed-effect concentration for Copepoda, <0.1 μg/L). The question remains, however, of whether long-term (in)direct effects on the populations or the community may occur at the 0.1-μg/L treatment level.
Trends in 2,3,7,8-TCDD concentrations in fish tissues downstream of pulp mills bleaching with chlorine
Authors: Abbott Joan D. , Hinton Steven W.
Published: March 2010

Field measurements of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations in fish tissues from riverine environments impacted by treated pulp and paper industry effluent in the United States were analyzed. Data from 39 sites in 14 states across the four major U.S. paper-making regions were assembled and analyzed to determine the annual change in lipid-normalized concentrations of TCDD in fish tissue. The results provide strong evidence of a nationwide trend of decreasing lipid-normalized TCDD concentrations in fish tissue, with 84% of the examined sites showing a decrease. While the paucity of data currently limits any conclusions regarding the statistical significance at individual sites, the overall median rate calculated indicates a 0.36 annual fractional decrease in lipid-normalized concentrations of TCDD in fish tissue (0.18 to 0.51, 95% confidence interval); the average annual fractional decrease was 0.35 (0.23 to 0.47, 95% confidence interval). Subdividing fish into benthic and nonbenthic categories resulted in rates which were not significantly different from one another for both the median and mean statistics.
Enhanced antibody responses in mink (Mustela vison) exposed to dietary bleached-kraft pulp mill effluent
Authors: Smits Judit E. G. , Wobeser Gary A. , Haines Deborah M. , Blakley Barry R.
Published: March 2010

Mammalian top predators such as mink (Mustela vison) that inhabit a semi-aquatic environment may be exposed to bleached-kraft mill effluent (BKME), directly through the water, or indirectly through bioaccumulation of compounds in BKME via the food chain. To assess the potential immunotoxic effects of this exposure, the antibody response of 20 female mink exposed to dietary BKME for 26 weeks was studied. After 16 weeks on the BKME diet, sera were collected to determine prevaccination antibody levels against a mycobacterial antigen. Four weeks later, during early gestation, mink were immunized with a vaccine prepared from a culture of bacillus Calmette–Guérin (BCG). Sera were collected 6 weeks following vaccination and antimycobacterial antibody levels measured. A protein extract from cultured BCG was used as the capture antigen in an indirect enzyme-linked immunosorbent assay to quantify mink immunoglobulin specific for BCG. Both the control and BKME-exposed mink had significantly increased BCG antibody concentrations postimmunization compared to preimmunization levels. The BKME-exposed group antibody levels postimmunization were significantly higher (p = 0.029) than the corresponding control group. These results demonstrate immune modulation from dietary BKME, which was expressed as enhanced specific antibody production in mink. A related study describes cell-mediated immunosuppression in these BKME-exposed mink, supporting the hypothesis of immune deviation proposed here.
Metal-supplemented diets alter carbohydrate levels in tissue and hemolymph of gypsy moth larvae (Lymantria Dispar, lymantriidae, lepidoptera)
Authors: Ortel Johanna
Published: March 2010

Larvae of Lymantria dispar were exposed to two concentrations each of Cd, Pb, Cu, and Zn from hatching to day 3 of the fourth instar. The metals were applied via artificial diet (wheat germ diet); two control groups were reared on either an uncontaminated artificial diet (C) or on a natural diet (oak leaves, EF). High-pressure liquid chromatography (HPLC) was employed to analyze the hemolymph carbohydrates, whereas body glycogen and glucose were determined enzymatically. The results were analyzed with respect to diet-specific differences (oak leaves versus wheat germ diet) and metal exposure compared with the uncontaminated artificial diet. Hemolymph trehalose levels were higher in oak leaf-reared individuals than in those fed on the wheat germ diet (p < 0.01), whereas the opposite applied to the body glycogen and free glucose levels (p < 0.01). The average trehalose value of the control (C) (4.3 mg/ml) was reduced by metal contamination, dependent on both the metal itself and the concentration (Cd, Cu, Zn; 1.4–3.3 mg/ml). Sorbitol was not detected in the hemolymph of EF specimens, whereas it occurred in all artificial diet-fed groups. Metal- and dose-dependent differences in the hemolymph sorbitol levels were observed in the treatment groups, but not in the controls. Glycogen content increased in the low concentration of Cd, Pb, and Cu, whereas a decrease was observed for the low Cd and both Zn concentrations. Tissue free glucose was enhanced only in three of the metal groups. Generally, fresh and dry weights of larvae were reduced in all groups except the high Cu-contaminated one. The results may indicate that mass outbreaks of an important forest pest insect like L. dispar may be facilitated in metal-contaminated areas because parasitization success of antagonistic species may decline due to deterioration of nourishment within the metal-stressed host.
Uptake and depuration of polycyclic aromatic hydrocarbons from sediment by the zebrafish (Brachydanio Rerio)
Authors: Djomo J. E. , Garrigues P. , Narbonne J. F.
Published: March 2010

Zebrafish (Brachydanio rerio) were exposed for 30 d to individual 14C-labeled polycyclic aromatic hydrocarbons (PAHs) (anthracene, phenanthrene, pyrene, or benzo[a]pyrene) adsorbed on sediment. The uptake and depuration rate constants were measured. Rate of radioactivity release was measured under both contaminated (experiment 1) and clean (experiment 2) conditions. The results confirm that uptake and depuration rate constants were strongly related to physicochemical properties. However, the uptake from the water compartment was rapidly decreased in our microcosm system (–83% for anthracene and phenanthrene, –71% for pyrene, and –59% for benzo[a]pyrene within the first 2 d). For depuration in clean water, the half-lives of radioactivity loss from whole body were 63, 97, 115, and 138 h for anthracene, phenanthrene, pyrene, and benzo[a]pyrene, respectively, and were positively correlated with log Kow. In experiment 1 after 10 d, the remaining PAH concentrations were only about 16% of the maximum concentrations measured at time 24 h for anthracene, 12% for phenanthrene, 30% for pyrene, and 46% for benzo[a]pyrene. Kow appears to be a determining factor for partitioning constants for sorption to sediment, uptake, and release in aquatic organisms.
Life-stage-specific toxicity of sediment-associated chlorpyrifos to a marine, infaunal copepod
Authors: Green Andrew S. , Chandler Thomas G. , Piegorsch Walter W.
Published: March 2010

The life-stage-specific acute toxicity of sediment-associated chlorpyrifos to the marine, infaunal copepod, Amphiascus tenuiremis, was assessed. Chlorpyrifos is a common-use, high Kow, organophosphate pesticide. Duplicate 96-h tests were conducted with each major life stage of the copepod (adult, copepodite, and nauplius) exposed to sediments spiked with chlorpyrifos. Calculated median lethal concentrations (LC50s) were 66, 74, and 40 μg chlorpyrifos per kilogram sediment for the adult, copepodite, and nauplius stages, respectively. Analysis of covariance and logistical regression analysis on the mortality data revealed significant (α = 0.05) sensitivity differences for the life stages. The nauplius stage was significantly more sensitive than either the adult or copepodite stages. However, the copepodite stage showed no significant sensitivity difference versus the adult stage. The lowest-observed-effect concentrations (LOECs) also showed these relationships, with the naupliar LOEC being almost three times lower than that of either the adult or copepodite stages. A predicted sediment quality criterion (SQC) based on the equilibrium partitioning theory (EqPT) for chlorpyrifos was calculated to be 38 μg chlorpyrifos per kilogram sediment. This calculated criterion, supposedly protective of most sediment-dwelling invertebrates, was only 2 μg/kg lower than the LC50 for the nauplius life stage and far above the LOEC. An EqPT-derived SQC for chlorpyrifos clearly would not be protective of this meiobenthic copepod.
Potential impact of low levels of chlorsulfuron and other herbicides on growth and yield of nontarget plants
Authors: Fletcher John S. , Pfleeger Thomas G. , Ratsch Hilman C. , Hayes Robert
Published: March 2010

The influence of low application rates of chlorsulfuron on the growth and reproduction of four taxonomically diverse plant species (canola, smartweed, soybean, and sunflower) were examined. Exposures examined ranged from 1 × 10−3 to 8 × 10−3 of the recommended field rates for cereal crops and were approximately 1,000 times less than the highest exposure recommended by the U.S. Environmental Protection Agency. Each species received a single application at one of three different stages of reproductive development. Effects were determined by measuring the height and yield of mature plants. The comparative effects of four different herbicides (atrazine, chlorsulfuron, glyphosate, and 2,4-D) were determined in the same manner by exposing each test species to a single low dose at one of three critical stages of reproductive development.

Chlorsulfuron reduced the yield of all plants tested, with the amount of reduction depending on the time and rate of application. Most noteworthy was its influence on canola and soybean, in which at critical stages in development, applications of 9.2 × 10−5 and 1.8 × 10−4 kg/ha, respectively, reduced seed yields (dry wt) to 8 and 1% of those of controls without causing a significant change in vegetative growth. These low application rates are within the range of reported herbicide drift levels and suggest that chlorsulfuron may cause severe reduction in the yields of some nontarget crops if they are subjected to exposure at critical stages of development. Application of other herbicides at comparable rates and stages of plant development had no influence on either canola or soybean.
Long-term toxicity of five polycyclic aromatic hydrocarbons for the terrestrial isopods Oniscus Asellus and Porcellio Scaber
Authors: Van Brummelen Timco C. , Van Gestel Cornelis A. M. , Verweij Rudo A.
Published: March 2010

Polycyclic aromatic hydrocarbons (PAH) are a common component of soil pollution, yet little is known of the ecotoxicological risks these compounds may pose to life in soil. This article reports the ecotoxicity of five PAHs for two terrestrial isopod species. Isopods were exposed to food contaminated with four different concentrations of either fluorene, phenanthrene, fluoranthene (up to 4 μmol/g), benz[a]anthracene, or benzo[a]pyrene (up to 1.25 μmol/g). Exposure of Porcellio scaber lasted 16 weeks, and no adverse effects on survival, growth, or total protein (only females tested) were observed in any of the treatments. A small but significant reduction in growth of Oniscus asellus was observed at 47 weeks of exposure to 0.125 μmol benz[a]anthraceneṁg−1 dry weight and 1.25 μmol fluoreneṁg−1 dry weight and higher concentrations. A significant stimulation of the reproduction of O. asellus was observed in some of the phenanthrene, fluoranthene, benz[a]anthracene, and benzo[a]pyrene treatments; a larger proportion of the females were gravid, which resulted in a higher number of juveniles per female. Exposure did not significantly affect brood size, weight of the mother after release of the juveniles, or the survival of the juveniles upon starvation. Total protein content of females was significantly reduced at 0.4 μmol fluorene g−1 dry weight and higher concentrations. Growth and protein content of isopods is likely to be affected by PAH exposure only at highly contaminated sites. The ecological consequences of stimulated reproduction and possible DNA damage are poorly understood and require further attention because soil invertebrates may be exposed to PAHs over many generations.
Comparison of acute toxicity of process chemicals used in the oil refinery industry, tested with the diatom Chaetoceros Gracilis, the flagellate Isochrysis Galbana, and the zebra fish, Brachydanio Rerio
Authors: Roseth Svein , Edvardsson Trym , Botten Merete Tone , Fuglestad Jon , Fonnum Frode , Stenersen Jørgen
Published: March 2010

Chemicals under the trade names Nalco 537-DA, Nalco 625, Nalco 7607, Nalco 5165, Ivamin, and technical monoethanolamine are used extensively in the oil refinery industry. Aquatic toxicity tests were conducted using zebra fish fry (Brachydanio rerio) and the unicellular algae Isochrysis galbana (a flagellate) and Chaetoceros gracilis (a diatom). Inhibition of cell division, chlorophyll content, and 14CO2 uptake in the algae were sensitive end points. The effective concentrations (EC50s) of growth inhibition were 0.1 mg/L (Ivamin; I. galbana), 0.8 mg/L (Nalco 7607; I. galbana), 6 mg/L (Nalco 625; I. galbana), 10 mg/L (Nalco 5165; C. gracilis), and 15 mg/L (Nalco 537-DA; C. gracilis). The lethal concentrations (LC50s) (96 h) toward zebra fish fry was 1 mg/L for Nalco 7607, 6.5 mg/L for Nalco 537-DA, 7.1 mg/L for Nalco 625, and 20 mg/L for Ivamin 803. Monoethanolamine had an LC50 higher than 5,000 mg/L. Nalco 5165 was not tested on fish fry. The heartbeat frequency of fish embryos was reduced by 2.5 mg/L Nalco 537-DA, but this was an insensitive end point for the other chemicals.
Sediment quality assessment studies of Tampa bay, Florida
Authors: Carr Scott R. , Chapman Duane C. , Long Edward R. , Windom Herbert L. , Thursby Glen , Sloane Gail M. , Wolfe Douglas A.
Published: March 2010

A survey of the toxicity of sediments throughout the Tampa Bay estuary was performed as part of the National Oceanic and Atmospheric Administration's National Status and Trends Program. The objectives of the survey were to determine the spatial extent and severity of toxicity and to identify relationships between chemical contamination and toxicity. Three independent toxicity tests were performed: a 10-d amphipod survival test of the whole sediments with Ampelisca abdita, a sea urchin fertilization test of sediment pore water with Arbacia punctulata, and a 5-min Microtox® bioluminescence test with solvent extracts of the sediments. Seventy-three percent of the 165 undiluted sediment pore-water samples were significantly toxic relative to reference samples with the sea urchin fertilization test. In contrast, only 2% of the 165 samples were significantly toxic in the amphipod tests. The causes of toxicity were not determined. However, concentrations of numerous trace metals, pesticides, polychlorinated biphenyl (PCB) congeners, polycyclic aromatic hydrocarbons (PAHs), and ammonia were highly correlated with pore-water toxicity. Concentrations of many substances, especially total dichlorodiphenyltrichloroethanes (DDTs), endrin, total PCBs, certain PAHs, lead, and zinc, occurred at concentrations in the toxic samples that equaled or exceeded concentrations that have been previously associated with sediment toxicity.
Implications of defining test acceptability in terms of control-group survival in two-group survival studies
Authors: Bailer John A. , Oris James T.
Published: March 2010

Tests used to screen for toxic responses often involve the comparison of samples from a putatively contaminated site with a clean reference site. If attention is focused on mortality, then the difference in proportionate mortality/survival in the two groups serves as the basis of statistical inference. As a precursor to conducting such studies, criteria for judging test acceptability, including the minimum level of control survivorship and the number of organisms to be put on test, must be determined. In this article, we review the standard statistical methodology for calculating sample size requirements for two-group comparisons of proportions to highlight the effect of defining test acceptability in terms of survival in the control group. For a fixed level of power, false-positive (type I) error rate, and effect size, we show that lower control-group survival implies the need to place more organisms on test.
Validation of a short-term toxicity test endpoint by comparison with longer-term effects on larval red abalone Haliotis rufescens
Authors: Conroy Patrick T. , Hunt John W. , Anderson Brian S.
Published: March 2010

Experiments were conducted to compare a short-term 48-h aquatic toxicity test endpoint of abnormal larval shell development with other, more clearly adverse effects. In similar experiments conducted with two different toxicants, zinc sulfate and bleached-kraft mill effluent, red abalone (Haliotis rufescens) embryos were simultaneously exposed to identical dilution series and incubated for three different exposure periods: 48 h, 48 h followed by an 8-d recovery period in clean seawater, and 10 d of continuous exposure. Abnormal larval shell development was assessed in the 48-h short-term tests, and inhibition of metamorphosis was assessed in the exposure-recovery and continuous exposure experiments. For the zinc experiments, the median effective concentration (EC50) values for the 48-h exposure, the exposure-recovery experiment, and the continuous exposure experiment were 40, 34, and 32 μg/L zinc, respectively. For the bleached-kraft mill effluent experiments, the EC50 values were 0.98, 0.76, and 0.69% effluent, respectively. Results indicate that toxicant concentrations causing abnormal larval shell development also inhibit metamorphosis and that larvae exposed to toxicant concentrations which inhibit larval shell development do not recover to metamorphose when transferred to clean seawater. None of the successfully metamorphosed postlarvae had deformed larval shells, indicating that shell deformity precludes survival past the planktonic stage. A longer (15-d) experiment allowed measurement of postlarval shell length in exposed postmetamorphic abalone. Insignificant differences in postlarval shell length indicated that the timing of larval metamorphosis was similar regardless of toxicant exposure and that the effects of the toxicant was to inhibit rather than to delay metamorphosis.
Integrating chemical and biological remediation of atrazine and S-triazine-containing pesticide wastes
Authors: Arnold Scott M. , Hickey William J. , Harris Robin F. , Talaat Rasmy E.
Published: March 2010

Fenton's reagent (FR) and the catabolic activity of Rhodococcus corallinus and Pseudomonas sp. strain D were combined to detoxify s-triazines in pure solutions and mixed wastes. In solutions containing only atrazine, complete atrazine decomposition was accomplished with 2.69 mM FR. But FR treatment was not complete in a remediation context because stable, potentially carcinogenic chlorinated products accumulated as end products. Rhodococcus corallinus degraded these products in ≤10 min and produced 47% 14CO2 from [2,4,6-14C]atrazine in 7 d. Combining R. corallinus with Pseudomonas sp. strain D increased 14CO2 production to 73%. When applied to a pesticide rinse water containing atrazine, cyanazine, alachlor, metolachlor, and EPTC, ≥99% of the pesticides were degraded with 12.2 mM FR. Subsequent treatment with R. corallinus and Pseudomonas sp. strain D degraded all chlorinated s-triazine intermediates and released 70% 14CO2 from a [2,4,6-14C]atrazine tracer in 10 d. Use of R. corallinus obviated the need for additional chemical pretreatment, e.g., acidification or base hydrolysis, used in previous studies prior to microbial incubations. Thus, this method has potential as an on-site treatment for pesticide rinse water.
Aqueous solubility of permethylsiloxanes (silicones)
Authors: Varaprath Sudarsanan , Frye Cecil L. , Hamelink Jerry
Published: March 2010

The aqueous solubility of several low mlecular weight linear, cyclic, and branched permethylsiloxanes was determined at room temperature. A method for preparing molecularly dispersed, colloid-free saturated aqueous solutions is described. Solubilities, decreasing with increased molecular weights, ranged downward from one part per million to mere parts per trillion. The cyclic oligomers were slightly more soluble than their linear analogues. While the effect of branching was mixed, polar groups such as phenyl and hydroxyl moities sharply increased aqueous solubility. Semilog plots of the solubility/molecular weight yielded linear regressions, the extrapolation of which indicate the absence of any environmentally relevant water solubility (< 1 ppt) for the conventional higher molecular weight polydimethylsiloxanes of commerce.
Time-dependent isotherm shape of organic compounds in soil organic matter: Implications for sorption mechanism
Authors: Xing Baoshan , Pignatello Joseph J.
Published: March 2010

Batch 1-, 30-, and 180-d sorption isotherms were constructed for 1,3-dichlorobenzene, 2,4-dichlorophenol, and metolachlor (2-chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxy-1-methylethyl] acetamide) in aqueous suspension of a fine sandy loam soil (3% organic matter) and a peat soil (93% organic matter) at sorptive concentrations ranging over three to five orders of magnitude. The isotherms were fitted to the Freundlich model, S = KCN, where S and C are the sorbed and solution-phase concentrations and K and N are constants. Both K and N were time-dependent. K increased by as much as 2.7-fold beyond the 1-d period. N was less than unity in all cases and decreased with increasing sorption. Also, the isotherms were operationally separated into a “fast” fraction (amount sorbed after 1 d) and a “slow” fraction (amount sorbed thereafter). Ns was significantly smaller than Nf in all systems tested. The results show that partitioning in soil organic matter (SOM) is appreciably less ideal for the slow fraction. It is concluded that SOM has both partition and adsorption domains analogous to the dual-mode sorption model of glassy polymers. The adsorption component is more prominent for the slow fraction, indicating that the adsorption sites are internal to the SOM matrix and unevenly distributed with respect to access by sorbing molecules. Sorption by these natural materials was compared with sorption by polyvinylchloride, a glassy polymer that exhibits dual-mode sorption. That system gave nonlinear isotherms with an N that was invariant with time, consistent with its nature as a homogeneous polymer having evenly distributed adsorption sites.
Mercury contamination and population-level responses in chironomids: Can allozyme polymorphism indicate exposure?
Authors: Woodward Lee Ann , Mulvey Margaret , Newman Michael C.
Published: March 2010

Allozyme frequencies of Chironomus plumosus were determined along a gradient of sediment mercury concentrations in a contaminated lake. We examined whether allozyme frequencies could be used to distinguish populations along the gradient or between contaminated and reference sites. No significant correlations were found between allozyme frequencies and contamination, but an overall deficit of heterozygotes (in nine of 13 loci examined) was found at all sites sampled. While toxicant stress could be the cause, a more parsimonious explanation would be sampling over a patchy population structure leading to a heterozygote deficiency (i.e., Wahlund effect). Examination of allozyme frequencies along a transect indicated that the observed deficiency of heterozygote genotypes was due to sampling across some fine-scale substructuring of the populations. The findings of these studies lend a note of caution regarding the use of allozymes to infer population effects of contaminants or their potential use as biomarkers. Studies must define population structure, naturally occurring variation within and among populations, and relevant ecological factors in conjunction with the presence of xenobiotics and their concentrations.
Accumulation of hsp70 in juvenile and adult rainbow trout gill exposed to metal-contaminated water and/or diet
Authors: Williams Jeanne H. , Petersen Nancy S. , Young Patricia A. , Stansbury Mark A. , Farag Aida M. , Bergman Harold L.
Published: March 2010

The accumulation of heat shock cognate (hsc)/heat shock protein (hsp) 70 was measured in gill and liver from juvenile and adult rainbow trout (Oncorhynchus mykiss) exposed to waterborne metals and/or fed a metal-contaminated diet. These experiments are part of a larger study in which physiological responses were documented in adult and juvenile rainbow trout after exposure to food-borne and/or waterborne metals for 21 d. Western blot analyses were used to measure the accumulation of hsp70 and hsc70. Hsc/hsp70 levels were significantly increased in gills of juveniles exposed to metals, in both water and food. The importance of metals in the diet as well as the water was confirmed for the juveniles. Significant increases in hsp/hsc70 could not be demonstrated in the adults.
Teratogenic and genotoxic responses of larval Chironomus salinarius group (diptera: Chironomidae) to contaminated sediment
Authors: Hudson Lori A. , Ciborowski Jan J. H.
Published: March 2010

Chironomids are important indicators of the effects of sediment-bound contaminants. However, cause–effect relationships between contaminant exposure and stress-related indicators other than growth and survival have not been demonstrated. In the laboratory, we conducted 10-d exposures of Chironomus salinarius group Kieffer larvae to mixtures of contaminated (Trenton Channel, Detroit River, MI) sediment diluted with uncontaminated, formulated sediment (sand, sculptor's clay, and potting soil) in ratios of 1:0, 1:1, 1:3, 1:7, 1:15, and 0:1. Larvae were inoculated into either recently mixed sediments or those allowed to age for 7 d. Surviving larvae were examined for mouthpart (mentum) deformities. Giant chromosomes of the salivary glands were examined for reduction in relative nucleolus diameter (RND). Proportions of larvae with mentum deformities and of larvae with reduced RND increased linearly with each doubling of concentration of contaminated sediment. Deformities and RND reduction in individual larvae were independent responses. Incidences of deformities at low contamination doses were much greater for recently mixed sediments than for more aged sediments. Sediment age did not affect incidence of reduced RND except in the most contaminated treatment. Mentum deformities and reduced RND are quantifiable sublethal attributes reflecting stress responses to sediment contamination that can complement more traditional measures (survival and growth) in chironomid sediment bioassays.
Elimination rates of selected di-Ortho, mono-ortho, and non-orthosubstituted polychlorinated biphenyls in rainbow trout (oncorhynchus mykiss)
Authors: Coristine S. , Haffner G.D. , Ciborowski J.J.H. , Lazar R. , Nanni M.E. , Metcalfe C.D.
Published: March 2010

In order to determine the influence of chlorine substitution pattern on elimination rate constants for polychlorinated biphenyls (PCBs), 60 rainbow trout (Oncorhynchus mykiss) were intraperitoneally injected with corn oil spiked with a mixture of 13 tetra- to hexachlorobiphenyls. The mixture consisted of four di-ortho congeners (International Union of Pure and Applied Chemistry no. 52, 47, 101, and 153), five mono-ortho congeners (66, 105, 118, 119, and 156), and four non-ortho congeners (81, 77, 126, and 169). The range in growth-corrected elimination rate constants for the non-ortho-substituted PCBs was 0.003 to 0.015 μg/kg per d. The range of elimination rate constants for the mono-ortho PCBs was 0.007 to 0.012 μg/kg per d, and the range for the di-ortho PCBs was 0.004 to 0.011 μg/kg per d. Multivariate analysis of covariance revealed a highly significant interaction between chlorine substitution pattern and time (p < 0.001), suggesting that substitution pattern influences elimination kinetics. Kow and time also revealed a significant interaction (p < 0.001). As structure can influence rates of chemical elimination, exposure dynamics of PCBs are a function of both hydrophobicity and substitution patterns. The study confirms the observation that the predicted rate of decline of some of the more toxic non-ortho PCBs might be less than that observed for total PCBs.
Bioaccumulation and metabolism of benzo[A]pyrene in three species of polychaete worms
Authors: Driscoll Susan Kane , McElroy Anne E.
Published: March 2010

Polychaete worms which inhabit and ingest contaminated sediments may be exposed to a suite of sediment-sorbed xenobiotics, including polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (BaP). This study compared the accumulation and metabolism of sediment-sorbed BaP among various populations of polychaetes, including Leitoscoloplos fragilis, Nereis diversicolor, and Scolecolepides (= Marenzellaria) viridis. After exposure to trace amounts of BaP in sediment, N. diversicolor and S. viridis were found to metabolize BaP extensively, but metabolism of BaP appeared to be much slower in L. fragilis. Within each species, no consistent, significant differences in extent of BaP metabolism were observed between worms collected from contaminated versus reference sites. This result suggests that metabolism of BaP was not induced in worms from contaminated sites. To examine the extent to which metabolism of BaP is inducible in these species, worms were exposed in the lab to 3-methylcholanthrene (3MC), a potent inducer of PAH metabolism in other species. Only one species, S. viridis, showed a small increase in the percent of total tissue BaP that was biotransformed after treatment with 3MC. Whether or not worms were treated with 3MC, biota-sediment accumulation factors (lipid- and organic carbon-normalized tissue to sediment ratios) were highest for L. fragilis.
Effect of sediment organic carbon on the toxicity of a surfactant to Hyalella azteca
Authors: Cano Manuel L. , Dyer Scott D. , Decarvalho Alvaro J.
Published: March 2010

According to current sediment bioavailability models (e.g., equilibrium partitioning), toxicity of sorptive compounds in sediment depends on the free concentration in interstitial water. This free concentration may depend on both the characteristics of the compound and the sediment. For the sorption of anionic surfactants, sediment organic carbon content and cation exchange capacity have been shown to be important factors; however, it is not clear how these factors affect toxicity. Determining toxicity of these compounds in sediment using traditional batch sediment tests has not been entirely successful in the past due to excessive loss of parent material via biodegradation. In this study, effects of organic carbon on anionic surfactant toxicity were determined using highly branched alkylbenzene sulfonate (ABS) as the test compound in order to limit losses from biodegradation. Sediments were amended with peat moss to investigate the effects of organic carbon on surfactant sorption and toxicity to Hyalella azteca. Results support previous hypotheses regarding the effect of organic carbon on bioavailability and toxicity. Apparent sorption coefficients (Kapp) increased with higher organic carbon levels. Likewise, greater sediment concentrations of ABS were required to elicit toxic responses at greater organic carbon concentrations. Toxicity in sediment appeared to be due to interstitial water exposure.