bluuebunny/crossref_metadata_2025 huggingface dataset:
Relation among cytochrome p450, ah-active pcb congeners and dioxin equivalents in pipping black-crowned night-heron embryos
Authors: Rattner Barnett A. , Hatfield Jeff S. , Melancon Mark J. , Custer Thomas W. , Tillitt Donald E.
Published: March 2010

Pipping black-crowned night-heron (Nycticorax nycticorax) embryos were collected from a relatively uncontaminated site (next to Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). Hepatic cytochrome P450-associated monooxygenases and cytochrome P450 proteins, induced up to 85-fold relative to the reference site, were associated with concentrations of total polychlonrinated biphenyls (PCBs) and 11 PCB congeners that are presumed to express toxicity through the arylhydrocarbon (Ah) receptor Multiple regression revealed that up to 86% of the variation of cytochrome P450 measurements was accounted for by variation in the concentration of these PCB congeners. Toxic equivalents (TEQs) of sample extracts, predicted mathematically (summed product of PCB congener concentrations and toxic equivalency factors), and dioxin equivalents (TCDD-EQs), derived by bioassay (ethoxyresorufin-O-dealkylase activity of treated H4IIE rat hepatoma cells), were greatest in Cat Island samples. Cytochrome P450-associated monooxygenases and cytochrome P450 proteins were related to TEQs and TCDD-EQs; adjusted r2 often exceeded 0 5 for the relation among mathematically predicted TEQs and cytochrome P450 measurements. These data extend previous observations in heron embryos of an association between P450 and total PCB burdens to include Ah-active PCB congeners, and presumably other compounds, which interact similarly with the Ah receptor Benzyloxyresorufin O-dealkylase, ethoxyresorufin O-dealkylase, and cytochrome P450 1A appear to be the most reliable measures of exposure to Ah-active PCB congeners in black-crowned night-heron embryos. These findings provide further evidence that cytochrome P450-associated parameters have considerable value as a biomarker for assessing environmental contamination of wetlands
Low ph effects on swimming activity of Ambystoma salamander larvae
Authors: Kutka Franz J.
Published: March 2010

Swimming activity of larval Ambystoma laterale increased linearly with pH between pH 4.0 and 6.5; near inactivity occurred at pH 4.0. Ambystoma maculatum exhibited a weaker relationship between activity and pH, and overall was less active than A. laterale. However, survival of larval A. maculatum declined linearly with pH in the presence of adult diving beetles (Dytiscus verticalis), with significantly lower survival below pH 4.8. These results suggest that, as with embryos, salamander larvae may suffer from pH levels below 5.0, even though these levels are not directly lethal. Because of their sensitivity, ease, and short duration, activity tests are recommended with amphibian larvae for use in other risk assessments.
The role of grazers and shredders in the retention and downstream transport of a pcb in lotic environments
Authors: Sallenave Rossana M. , Day Kristin E. , Kreutzweiser David P.
Published: March 2010

Field studies using flow-through artificial stream channels were conducted between May and October 1992 to study the role of the feeding activity of grazing and shredding invertebrates in promoting downstream transport of 2,2′,4,4′,5,5′-hexachlorobiphenyl (HCBP). Plant material was labeled with [14C]HCBP and fed to selected invertebrate species, and accrual of radioactivity by downstream collector species (Hydropsyche spp.) was measured. Downstream transport of HCBP was significantly increased by the presence of the grazer Elimia livescens in the upstream sections of the channels as demonstrated by significantly higher levels of radioactivity in hydropsychid larvae located downstream. Similarly, movement of HCBP downstream was significantly greater in channels containing the shredder Hydatophylax argus than in channels without shredders. These results suggest that the feeding processes of benthic invertebrates may play an important role in the downstream transport of particle-bound hydrophobic organic compounds.
A comparison of algorithms for global characterization of confidence regions for nonlinear models
Authors: Klepper Olivier , Hendrix Eligius M. T.
Published: March 2010

Environmental models are often highly nonlinear, and parameters have to be estimated from noisy data. The standard approach of locally linearizing the model, which leads to ellipsoid confidence regions, is inappropriate in this situation. A straightforward technique to characterize arbitrary-shaped confidence regions is to calculate model output on a grid of parameter values. Each parameter value P results in a goodness of fit G(P), which allows delineation of the set of parameters corresponding to G(P) < Gc, with Gc some threshold level (e.g., 5% probability). This approach is impractical and time-consuming for complex models, however. This article aims at finding an efficient alternative. It is first shown that the most general approach is to generate parameter values uniformly covering the set G(P) < Gc rather than finding the boundary G(P) = Gc. It is argued that the most efficient method of generating a uniform cover is by a (theoretical) algorithm known as pure adaptive search (PAS); the presently proposed method (uniform covering by probabilistic rejection; UCPR) is shown to be a good approximation to PAS. The UCPR is compared with alternative methods for a number of test problems. It is illustrated that for complex models (where model run time dominates total computer time) UCPR is considerably faster and its cover of Gc more uniform than existing alternatives. An intrinsic problem common to all methods is that the amount of work increases at least quadratically with the number of parameters considered, making them of limited use for high-dimensional problems.
Laboratory measurements of the aqueous solubility of mixtures of chlorinated solvents
Authors: Broholm Kim , Feenstra Stan
Published: March 2010

This article describes the results of laboratory batch solubility experiments with five chlorinated solvents (chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene) present alone or in binary or ternary mixtures. The measured aqueous solubility values of the pure compounds revealed significant deviation from the widely used literature values for trichloroethylene and tetrachloroethylene. The experiments with binary and ternary solvent mixtures showed that the chlorinated solvents used in this study exhibited close to ideal behaviour. That means the concentration of an organic compound in the aqueous phase in equilibrium with an organic phase can be described as the mole fraction in the organic phase times the aqueous solubility of the pure compound. The UNIFAC (universal quasi chemical functional group activity coefficients) method was used in this study to estimate the appropriate activity coefficients for the experiments with binary mixtures. The UNIFAC method predicted nonideal behaviour for some of the mixtures. However, the deviation was only significant at relatively low mole fractions. Experiments indicated that the assumption of ideal behaviour for the chlorinated solvents used in this study is a reasonable one. The assumption of ideal behaviour simplifies the use of models to simulate the dissolution of chlorinated solvent mixtures in ground water.
Effect of alachlor concentration and an organic amendment on soil dehydrogenase activity and pesticide degradation rate
Authors: Felsot Allan S. , Dzantor E. Kudjo
Published: March 2010

Past studies have shown that extremely high concentrations of alachlor in soil can depress microbial biomass and bioactivity; consequently, degradation of alachlor is also inhibited. Studies were undertaken to further characterize the relationship among alachlor concentration in soil, dehydrogenase activity (as an indicator of microbial activity), and degradation rate. Alachlor initially inhibited soil dehydrogenase in soil at concentrations as low as 250 mg/kg with prolonged inhibition through at least 21 d occurring at concentrations ≥750 mg/kg. The inhibition of soil dehydrogenase was associated with a prolonged persistence of alachlor beyond the previously reported ranges of half-life observed at normal field rates of application. Amendment of soil with cornmeal caused degradation of 10 to 250 mg/kg alachlor at rates substantially faster than previously reported for laboratory incubations. At alachlor concentrations ≥750 mg/kg, dehydrogenase activities in amended soils surpassed levels in corresponding no-pesticide controls after 21 d; coincidentally, >50% of the initially added alachlor had degraded during the same period. These results suggested that stimulation of microbial bioactivity by addition of organic amendments may enhance co-metabolism of high concentrations of pesticides in soil.
Phytotoxicity and accumulation of mercury in tobacco subjected to different exposure routes
Authors: Suszcynsky Elaine M. , Shann Jodi R.
Published: March 2010

Experiments were conducted to study the absorption, phytotoxicity, and internal distribution of mercury (Hg) in tobacco plants (Nicotiana miersii) exposed to elemental mercury vapor (Hg0) through the shoot or to ionic mercury (Hg2+) through the root. Tobacco plants grown hydroponically were exposed to varying Hg0 treatment concentrations (0 to 100 mg/m3) in a specially designed chamber system, examined for visible symptoms of toxicity, and analyzed for Hg content by cold vapor atomic absorption, 1 and 10 d following treatment. In a separate experiment, the roots of hydroponic tobacco plants were exposed to Hg2+ in the form of a mercury chloride solution (0 to 100 μg/ml) and analyzed for growth changes and Hg content. Accumulation, toxicity response, and Hg distribution differed between the two exposure routes, even when internal Hg concentrations in the treated plants were similar. Plants exposed to Hg0 accumulated Hg in the shoots with no movement to roots. Visible signs of Hg0 stress were apparent at 1.0 mg/m3 exposure levels and greater. Root-exposed plants showed accumulation of Hg in the roots with movement to the shoots by day 10. Inhibition of root and shoot growth occurred at treatment levels of 1.0 μg/ml and greater with very limited tissue damage at higher treatment levels.
Toxicity of selected pesticides to lake phytoplankton measured using photosynthetic inhibition compared to maximal uptake rates of phosphate and ammonium
Authors: Brown L.S. , Lean D.R.S.
Published: March 2010

The toxicity of 16 pesticides to the energy-producing process of photosynthesis was determined from inhibition or depression of the assimilation rate of [14C]bicarbonate by natural plankton samples collected from Jack's Lake, a mesotrophic lake on the edge of the Canadian Shield 200 km northeast of Toronto, Ontario. Measurements were made at increasing concentrations of pesticide while samples were exposed to optimal light. At the same time, in the same 300-ml bottle, measurements of maximal uptake rates for phosphate and ammonium were made using radiotracer and stable isotope methods. In this way the more commonly used screening technique of photosynthetic inhibition could be compared to the energy-demanding processes of phosphate and ammonium uptake. Phosphate assimilation was inhibited at much higher herbicide concentrations than carbon fixation, whereas ammonium assimilation was inhibited at intermediate concentrations. Herbicides that specifically inhibit photosynthesis were most toxic to carbon uptake, while those herbicides affecting other cellular metabolic processes had a greater influence on phosphate and ammonium assimilation. No relationship was found among pesticide toxicity and molecular weight, solubility, or log Kow.
Heavy metal detoxification by trimercapto-s-triazine (TMT) as evaluated by a bacterial enzyme assay
Authors: Ayoub George M. , Koopman Ben , Bitton Gabriel , Riedesel Kelly
Published: March 2010

We compared trimercapto-s-triazine (TMT) to ethylenediaminetetraacetate (EDTA) for detoxification of five selected heavy metals as part of an effluent fractionation procedure. Toxicity was assessed using a microbial microplate assay, based on the MetPAD™ test kit. The affinity of TMT to four of the metals (Cd, Cu, Hg, Pb) was on the same order of magnitude as EDTA, as indicated by minimum mole ratios of ligand to metal required for detoxification. The TMT was ineffective against Zn. Both TMT and EDTA were toxic (causing more than 30% inhibition) to the test bacterial enzyme at concentrations of 3,000 μM or greater. The range of TMT concentrations that detoxified the metals was broader than that of EDTA. Stimulation of enzyme activity by EDTA could complicate interpretation of test data, a problem not shared by TMT.
Reduction of the efficiency of extraction of lipophilic chemicals from water by dissolved organic matter
Authors: Maguire R James , Batchelor Suzanne P , Sullivan Cheryl A
Published: March 2010

A study was made of the efficiency of liquid-liquid extraction of eight chlorinated hydrocarbons of varying lipophilicity from filtered (1 μm) organic free water, soil humic acid solution, lacustrine dissolved organic matter solution, and a natural water The efficiency of hexane extraction of the spiked chemicals without pH adjustment (i e the conventional technique) was reduced with increasing concentration of dissolved organic matter (DOM) and increasing chemical lipophilicity At the same time, increasing amounts of the more lipophilic chemicals were found in subsequent extracts of the water at pH 12, and after chromic acid oxidation of the DOM The results indicated that conventional liquid-liquid extraction underestimates the concentrations of “dissolved” highly lipophilic chemicals in fresh water, the extent of the underestimation depending upon the nature of the DOM Sixteen day exposure experiments with filtered natural waters containing roughly 5 mg/L DOM indicated that 6 to 8% of the most lipophilic chemical tested, mirex, was not recovered by standard hexane extraction without pH adjustment, with 5 mg/L of a soil derived humic acid, 49% of mirex was not recovered by standard hexane extraction without pH adjustment For highly lipophilic chemicals that are not destroyed by chromic acid oxidation, it is recommended that total concentrations in filtered or centrifuged fresh waters be determined by the chromic acid oxidation/extraction technique
Induction of cytochrome P4501A in the mummichog (Fundulus heteroclitus) by the polychlorinated terphenyl formulation aroclor 5432
Authors: Gallagher Kathryn , van Veld Peter A. , Hale Robert C , Stegeman John J
Published: March 2010

Accumulation of the polychlorinated terphenyl formulation Aroclor 5432 in aquatic species has previously been reported Polychlorinated terphenyls (PCTs) are structurally similar to polychlorinated biphenyls (PCBs), and were used in related applications However, their biological effects have not been thoroughly studied Effects of PCT mixtures on levels of hepatic cytochrome P4501A (P4501A) and associated ethoxyresorufin O-deethylase (EROD) activity in the mummichog (Fundulus heterochtus), a common estuarine fish, were assessed here Fish were injected intraperitoneally with PCT formulations Aroclor 5432, Aroclor 5460, or the PCB formulation Aroclor 1254, at doses of 0 32 to 100 mg/kg body weight Elevated levels of P4501A and EROD activity were detected in fish injected with Aroclor 5432 and Aroclor 1254 doses of 32 and 100 mg/kg Induction resulting from Aroclor 5432 was greater than that caused by equivalent doses of Aroclor 1254 Treatment with Aroclor 5460 did not result in significant induction Because commercial PCT mixtures contain small amounts of PCBs, the PCB components may have contributed to the induction observed for Aroclor 5432 This work represents the first report of hepatic cytochrome P4501A induction caused by Aroclor 5432 in teleosts and, similar to work in mammalian systems, suggests that the effects of this mixture may be at least partially mediated through Ah receptor binding
Comparative toxicant sensitivity of sexual and asexual reproduction in the rotifer Brachionus calyciflorus
Authors: Snell Terry W. , Carmona Maria Jose
Published: March 2010

Cyclically parthenogenetic zooplankters like rotifers are important tools for assessing toxicity in aquatic environments Sexual reproduction is an essential component of rotifer life cycles, but current toxicity tests utilize only asexual reproduction We compared the effects of four toxicants on asexual and sexual reproduction of the rotifer Brachionus calyciflorus Toxicants had a differential effect on sexual and asexual reproduction, with sexual reproduction consistently the most sensitive Concentrations of 0 2 μg/ml PCP (sodium pentachlorophenate) had no effect on the asexual reproductive rate, but significantly reduced sexual reproduction Likewise, chlorpyrifos concentrations of 0 3 μg/ml had no significant effect on asexual reproduction, but sexual reproduction was significantly reduced There was no difference in NOECs, LOECs, and chronic values for asexual and sexual reproduction for cadmium and naphthol tests However, comparison of toxicant effect levels revealed that sexual reproduction was more strongly reduced at each toxicant concentration The four toxicants tested inhibited sexual reproduction 2 to 68 times more than asexual reproduction at the lowest observed effect concentrations Toxicants inhibited sexual reproduction in its initial step sexual female production Because sexual reproduction is more sensitive, toxicity tests based exclusively on asexual reproduction may not be protective of rotifer life cycles
Transfer and accumulation of organochlorines from black-crowned night-heron eggs to chicks
Authors: Custer Thomas W. , Custer Christine M.
Published: March 2010

Eggs and sibling 1-, 3-, and 5-d-old chicks from seven black-crowned night-heron (Nycticorax nycticorax) broods were collected from Green Bay, Wisconsin, and analyzed for organochlorines. The concentration (μg/g) of nine organochlorines either decreased (n = 7) or remained the same (n = 2) as the chicks grew older. In contrast, the total mass (μg) of these nine organochlorines increased (n = 7) or remained the same (n = 2) as the chicks grew older. Accumulation rates of mass (μg/d) between egg and 5-d-old chicks for each of the nine organochlorines were positive and varied from 0.2 μg/d (p,p′-DDT) to 42 μg/d (PCBs). These results suggest that the loss of contaminant mass from eggs to chicks reported in some earlier studies was because the entire carcass was not analyzed (i.e., not including skin, gastrointestinal tract, etc.). These results also support the use of contaminant accumulation rates as an indicator of local contamination.
Effect of nonionic surfactant on the degradation of glass-sorbed pcb congeners by integrated chemical-biological treatment
Authors: Aronstein Boris N. , Paterek J. Robert
Published: March 2010

A study was conducted on the effect of a nonionic surfactant on the efficiency of the integrated chemical-biological treatment (ICBT) of polychlorinated biphenyls (PCBs) sorbed to the glass walls of the experimental vessels. The addition of surfactant associated with the chemical oxidation was proposed to overcome two limitations of biodegradation of hydrophobic compounds: adsorption to surfaces, and lack of solubility and thus availability to the microorganisms. Two 14C-labeled PCB congeners, 2-chlorobiphenyl and 2,2′,4,4′-tetrachlorobiphenyl, were used as the test compounds. The integrated chemical-biological treatment consisted of sequential applications of Fenton's reagent (5% H2O2, 1 mM FeSO4) at pH 4.0 (with and without non-ionic surfactant Novel II 1412-60) and the inoculation with a mixed culture of Pseudomonas sp., strain LB400, and Alcaligenes eutrophus, strain H850, at pH 8.0. The chemical treatment in the presence of surfactant affected the removal of the congeners bound to the glass surfaces of the experimental test systems. As indicated by high-pressure liquid chromatography analysis, these PCBs were converted to unidentified soluble products that are hypothesized to be partial oxidation products. No parent test compounds were detectable in the system after chemical treatment with or without surfactant. The addition of the mixed culture of PCB-degrading bacteria after completion of chemical treatment in the presence of surfactant resulted in the removal of approximately 45 % of 2-chlorobiphenyl and 32% of 2,2′,4,4′-tetrachlorobiphenyl in the form of 14CO2. This compared to 29% and 23% without the addition of surfactant, respectively. We suggest that the combination of surfactant-induced desorption and chemical oxidation would increase the availability of hydrophobic pollutants for microbial degradation.
Does acid rain increase human exposure to mercury? A review and analysis of recent literature
Authors: Richardson G. Mark , Currie David J. , Egyed Marika
Published: March 2010

The literature suggests that acid deposition may lead to increased mercury (Hg) contamination of fish. Employing published empirical relationships, we have estimated the change in associated Hg contamination with an increase in sulphate deposition from 0.25 to 1.25 g sulfur/m2/year. In seepage lakes, one can predict that Hg in walleye from these lakes, and subsequent human exposure due to consumption of these fish, would be elevated at the higher rate of sulphate deposition. However, for drainage lakes, increasing acidic deposition was predicted to reduce Hg accumulation in lake trout and northern pike. Subsequent human exposure to Hg due to consumption of these species from drainage lakes was therefore also predicted to be lower at the higher rate of acidic deposition. We concluded that the hypothesis that acidic deposition increases mercury (Hg) contamination in fish, and thereby mercury exposure in humans via fish consumption, is only true for acidic deposition onto seepage lakes.
Organochlorine pesticide residues in Southern Ontario spring peepers
Authors: Russell Ronald W. , Hecnar Stephen J. , Haffner G. Douglas
Published: March 2010

Spring peepers (Pseudacris crucifer) were analyzed by GC-ECD for 15 organochlorine pesticides of environmental significance. Only DDT, DDE, DDD, and dieldrin showed significant tissue accumulations in spring peepers. The area of collection had a history of extensive DDT application for mosquito control, but the practice of pesticide application was abandoned 26 years ago. Local extinctions of amphibians have been documented in the immediate area, and the long-term effects of organochlorine pesticide exposure are implicated as plausible causes of these extinctions.
Freshwater mussel die-off attributed to anticholinesterase poisoning
Authors: Fleming W. J. , Augspurger T. P. , Alderman J. A.
Published: March 2010

In 1990, we investigated a die-off of freshwater mussels in north-central North Carolina. An estimated 1,000 mussels of several species were found dead or moribund, including about 111 Tar spinymussels (Elliptio steinstansana) a federally listed endangered species. The die-off occurred during a period of low flow and high water temperature in a stream reach dominated by forestry and agriculture. Pathological examinations did not show any abnormalities and indicated that the die-off was an acute event. Chemical analyses of mussels, sediments, and water revealed no organophosphorus or carbamate pesticides. Cholinesterase activity in adductor muscle from Eastern elliptios (Elliptio complanata) collected at the kill site and downstream was depressed 73 and 65%, respectively, compared with upstream reference samples. The depression is consistent with a diagnosis of anticholinesterase poisoning. This is the first documented case in which cholinesterase-inhibiting compounds have been implicated in a die-off of freshwater mussels.
Effect of surfactant addition on phenanthrene biodegradation in sediments
Authors: Tsomides Harry J. , Hughes Joseph B. , Thomas J. Michelle , Ward C. Herb
Published: March 2010

A laboratory study was conducted to determine whether commercial surfactants enhance the bioremediation of PAH-contaminated sediments. Phenanthrene was chosen as a representative PAH; an inoculum of PAH-degrading microorganisms, enriched from an aquatic sediment, was used in sediment-water slurry microcosm biodegradation experiments. Of seven nonionic surfactants tested, only one (Triton X-100) did not inhibit phenanthrene mineralization at concentrations above the critical micelle concentration (CMC). Temporal studies on Triton X-100 revealed that while it initially inhibited mineralization in sediment-free microcosms, after 1 week Triton X-100 slightly improved phenanthrene biotransformation and mineralization in microcosms with and without sediment. For all treatments, phenanthrene disappearance was complete after 9 d, and mineralization reached 50 to 65% after 12 d. Sorption to the sediment appears to have reduced the free aqueous surfactant concentration, thereby reducing surfactant toxicity to the microorganisms. These results suggest that many surfactants are toxic to PAH-degrading microorganisms, and while surfactant addition may not always have adverse effects on biodegradation, the use of surfactants might not be desirable to achieve complete contaminant removal.
The toxic effects of direct pesticide exposure for a nontarget weed-dwelling chrysomelid beetle (Gastrophysa polygoni) in cereals
Authors: Kjaer Christian , Jepson Paul C.
Published: March 2010

Direct insecticide deposition on adults of the chrysomelid beetle Gastrophysa polygoni L. was measured by use of fluorescent spray tracer. The beetles captured 1 .3-to 2.5–fold the spray volume of an equivalent area of weed leaf surface. This disproportionate rate of exposure declined down through the crop canopy toward the ground. Spray deposition was measured for insects placed on both the upper and the lower surfaces of Polygonum convolvulus L. leaves within winter wheat crop canopies. The upper-to-lower-surface deposition ratio was 2.3 irrespective of the position of the leaf in the crop canopy. The mortality of adult G. polygoni exposed to pesticides on their host plant was estimated, based on measurements of spray deposition on insects in different positions, the laboratory dose-response relationship for dimethoate, and the distribution pattern of adults on the host plant measured in the laboratory. At full recommended field rate (280 g ha−1) an expected 40.7% of the adult population would die as a result of direct exposure to dimethoate. The mortalities on specific positions on the plant ranged between zero and 76.7%. To reduce predicted mortality to a level of 10%, it would be necessary to reduce field rate to 50% according to these calculations. Those individuals surviving the dimethoate treatment had a reduced fertility, whereas the egg viability was unaffected.
Biodegradation of hydrophobic compounds in the presence of surfactants
Authors: Roch François , Alexander Martin
Published: March 2010

A study was conducted to determine the availability of hydrophobic compounds within surfactant micelles for microbial uptake. Several of the surfactants tested were toxic to the test bacteria and prevented biodegradation of biphenyl and phenanthrene at concentrations below the critical micelle concentration (CMC). The rate of biodegradation was reduced at a surfactant concentration above but not below the CMC only when the test bacterium grew on biphenyl in the presence of Triton X-100. This decrease was correlated with the CMC and was more pronounced at a biphenyl concentration of 0.2 μg/ml than at 2.0 μg/ml. Such a correlation was not observed when bacteria grew on 1.0 μg glutamate per ml, even though the rate of glutamate degradation was reduced by Triton X-100. Analysis of the data with a mathematical model suggested that the experimental observations were probably not the consequence of the unavailability to bacteria of biphenyl within Triton X-100 micelles.
Mutagenic potential of environmental samples before and after remediation of a solvent-contaminated site
Authors: Donnelly Kirby C. , Thomas James C. , Brown Kirk W.
Published: March 2010

Soil, sediment, and paint sludge samples were collected during a 4-year period from an abandoned solvent recovery site prior to and after site remediation. Samples were sequentially extracted with methylene chloride and methanol and redissolved in dimethyl sulfoxide for biological analysis. The mutagenic potential of the extracts was evaluated using the Salmonella/microsome assay with and without metabolic activation. Noncontaminated background soil samples collected off-site induced specific mutagenic activities that ranged from below detection to 28 net revertants per milligram of residue. Although several sludge samples induced specific activities that were relatively low, the maximum mutagenic response induced by a sludge sample was 1,258 net revertants per milligram of residue. Compared to background soil, elevated levels of mutagenic activity were also detected in the extracts of several samples collected from a drainage area downgradient from the waste storage pad and in the extract of sediment samples from a downgradient storm-water retention pond. The weighted activity of the noncontaminated background soil samples ranged from below detection to 15 revertants per gram of soil. The combined weighted activity of the sludge sample extracts ranged from below detection to 43,567 revertants per gram. The combined weighted activity of the extracts of samples collected after site remediation ranged from below detection to 1,273 revertants per gram. A visual inspection of the site following remediation suggested that all obvious signs of chemical contamination had been removed. However, the results from biological analysis indicate that soil collected following site remediation induced a weighted activity more than 30 times the maximum weighted activity observed in the noncontaminated background soil. These data suggest that additional site remediation is required if the genotoxic potential of soil is to be reduced to levels approximating those of noncontaminated background soil.
Degradation of silicone polymer in a variety of soils
Authors: Lehmann Robert G. , Varaprath Sudarsanan , Annelin Ronald B. , Arndt James L.
Published: March 2010

Previous studies on one soil showed that silicone polymer (polydimethylsiloxane, or PDMS) degrades to dimethyl-silanediol (DMSD). This study examines PDMS degradation on seven U.S. soils differing in pH, % organic matter, texture, mineralogy, and geographic origin. Moist soils were amended with 350-centistoke (cs) [14C]PDMS at 100 mg kg−1, and soils were dried at 23°C for 0, 2, 4, 7, 10, or 14 d. Foam plugs were inserted in tube necks to trap volatiles. Samples were extracted with water to monitor silanol formation, or with THF (tetrahydrofuran) for analysis of molecular weight changes and identification of degradates. In all soils, PDMS degraded extensively to low-molecular-weight, water-soluble products. Gas chromatography-mass spectrometry (GC-MS) identified the main product in all soils as DMSD. Other small silanols and cyclic siloxanes were either not detected or were present in only trace amounts. No volatile 14C was captured by the plugs, and quantitative recovery of 14C showed no loss of unidentified volatiles. PDMS degradation was thus similar in a wide range of soils, and DMSD was the main degradate. A lower limit of 4,900 ± 1,250 L kg−1 for the kd of this PDMS suggests that the polymer should be immobile in soil.
The effect of manipulations of freshwater sediments on responses of benthic invertebrates in whole-sediment toxicity tests
Authors: Day Kristin E. , Kirby R. Scott , Reynoldson Trefor B.
Published: March 2010

Manipulations of freshwater sediment were performed to remove indigenous organisms prior to conducting toxicity tests with three species of benthic invertebrates. The effects of these treatments on end points in bioassays were compared within and between two sediments, i.e., a “clean” sediment and a “contaminated” sediment. In addition, the effects of manipulations on the physicochemical structure of the two sediments and the presence of metals, PAHs, and PCBs in the contaminated sediment were examined. The amphipod Hyalella azteca was most sensitive to the manipulations and had low survival in sediment that was sterilized. Growth (milligrams dry weight per individual) was affected by the presence of contaminants. Survival of Chironomus riparius was not affected by any manipulation but was reduced by contaminants as well as indigenous organisms. Growth of C. riparius was higher in autoclaved sediment but lower in sediment containing endemic tubificid worms. Production of young by Tubifex tubifex increased in sediment that was irradiated, possibly due to increased detrital material. Particle size distribution, metals, nutrients, and PAHs varied little as a function of manipulation; however, sieving of sediment through 250-μm mesh did reduce percent total organic carbon (TOC), percent loss on ignition (LOI), and concentrations of some PCBs in either clean or contaminated sediment. Manipulation of sediments to remove endemic species should be determined on a case-by-case basis and is specific to the organisms used in toxicity tests.
Effects of diflubenzuron on the reproductive success of the bluegill sunfish, Lepomis macrochirus
Authors: Tanner Danny K. , Moffett Mary F.
Published: March 2010

Exposure to diflubenzuron concentrations of 2.5 μg/L reduced growth of young-of-the-year (Y-O-Y) bluegill by 56 and 86% in replicate enclosures and by 88 and 97% at 30 μg/L. An adult bluegill reproduction study was conducted in six littoral enclosures located in a 2-ha pond near Duluth, Minnesota. Decreased growth of Y-O-Y bluegill resulted from the reduction or elimination of preferred invertebrate prey items by diflubenzuron that led to different and/or less Y-O-Y food consumption. Adult bluegill behavior and spawning, embryo hatching, larval survival until swim-up, and Y-O-Y biomass were also studied. Before the first two diflubenzuron applications, spawning occurred in all enclosures; following the first application, spawning occurred in both control enclosures and one 30-μg/L enclosure. Successful embryo hatching and larval swim-up occurred in all enclosures prior to the first application, and in one control and one 30-μg/L enclosure following application. The Y-O-Y growth was the most sensitive end point, and Y-O-Y biomass was among the least sensitive end points for bluegill reproductive success. The Y-O-Y bluegills (and potentially other fish species) that are exposed to diflubenzuron concentrations of ≥2.5 μg/L may experience reduced growth, which can result in greater starvation, increased predation, reductions in over-winter survival, and diminished to poor recruitment.
A system for conducting flow-through toxicity tests with larval fish
Authors: Diamond Stephen A. , Oris James T. , Guttman Sheldon I.
Published: March 2010

We report here on an inexpensive, easily constructed, flow-through system for toxicant exposure of small organisms. Data are presented to illustrate the capacity of the system to maintain uniform toxicant concentrations relative to static renewal methods.
Genetic and demographic responses of mosquitofish (Gambusia holbrooki girard 1859) populations stressed by mercury
Authors: Mulvey Margaret , Newman Michael C. , Chazal Ann , Keklak M. Michele , Heagler M. Gay , Hales L. Stan
Published: March 2010

Genetic and demographic changes in mosquitofish populations are reported after chronic (111 d) exposure to mercury. Sex ratios, normally female-biased in field populations, were also female-biased in control mesocosms. However, the sex ratio was male-biased in the mercury treatments. Frequencies of glucosephosphate isomerase-2 (Gpi-2) allozymes for fish exposed to mercury differed from initial frequencies and from those of control fish. In a selection-component analysis, female sexual selection was statistically significant for the mercury-treated fish; the proportion of females that were gravid differed among Gpi-2 genotypes. The number of developing embryos per female also differed among Gpi-2 genotypes. Mercury had genotype-specific effects on mosquitofish reproduction in addition to genotype-specific effects on mortality reported earlier. These effects may reflect metabolic qualities of the Gpi-2 genotypes or loci closely linked to the Gpi-2 locus.
Short-term exposure to triphenyltin affects the swimming and feeding behavior of tadpoles
Authors: Semlitsch Raymond D. , Foglia Massimiliano , Mueller Alexandra , Steiner Isabelle , Fioramonti Ennio , Fent Karl
Published: March 2010

Triphenyltin compounds are used globally in agriculture as fungicides for a wide variety of crops. Their persistence in aquatic habitats and toxicity make them of special concern to amphibian species using temporary ponds or lakes for critical life-history functions. The effects of short-term exposure to three concentrations (5, 10, 20 μg/L) of triphenyltin chloride (TPT) were assessed for the swimming and feeding behavior of tadpoles of the European frog, Rana esculenta. The proportion of time spent swimming declined 33.8% with increasing TPT level. Treatments also had a significant effect on the proportion of time spent feeding, initially increasing in the acetone and lowest TPT treatments, but thereafter declining 19.6% with increasing TPT level. Tadpoles also compensated for reduced swimming by spending an increased proportion of activity time on feeding, but even this compensation declined at the highest TPT levels. Reduced swimming activity and food intake are likely to result in decreased growth and development as well as negatively influence adult traits such as size at maturity, survival to first reproduction, and fecundity.
Quantitative application of biodegradation data to environmental risk and exposure assessments
Authors: Larson Robert J. , Cowan Christina E.
Published: March 2010

Biodegradation is an important removal mechanism for natural and synthetic organic chemicals released to aquatic, benthic, and terrestrial ecosystems. It results in a decrease in the overall mass or load of chemicals present in the environment and is key in preventing the accumulation and persistence of chemicals in specific environmental compartments. Although biodegradation is an important process for minimizing potential adverse impacts on environmental systems, it has not been traditionally considered in a quantitative fashion in environmental risk assessments. This article outlines an approach and provides simple kinetic criteria for incorporating biodegradation rate data into environmental exposure and risk assessments. The approach is a generic one that relates biodegradation half-lives to chemical residence times in specific environmental compartments. It is broadly applicable to any organic chemical in a range of environmental compartments and has potential use as a technical and regulatory tool to better quantify environmental exposure and risk.
Ammonia variation in sediments: Spatial, temporal and method-related effects
Authors: Sarda Namrata , Burton G. Allen
Published: March 2010

In aquatic systems, ammonia is a common nutrient and pollutant that originates from both natural and anthropogenic sources. The effects of sediment and pore-water collection methods, and sediment spatial and temporal variability on ammonia concentrations, were evaluated. Sediment and pore-water collection methods included grab sampling with an Ekman dredge and hand corer followed by centrifugation, in situ suction, and in situ peeper methods. Samples were collected from three sites over a period of several months, with site replicates spaced from 30 to 60 cm and from 6 to 9 m apart. Pore-water ammonia concentrations differed significantly between the collection methods on most occasions. Ammonia concentrations were highest in the Ekman and corer pore-water samples as compared to the in situ pore waters collected from the peepers and by suction. Spatial heterogeneity in sediment ammonia concentrations was significant and generally increased with distance. Seasonal fluctuations in ammonia concentrations were evident, with high values in warmer months. Storage effects were observed with pore-water ammonia over a 1- to 4-week period. Results show that collection methods and natural variability contribute significantly to measured ammonia concentrations and are important considerations in aquatic ecosystem assessments.
A summary of the acute toxicity of 14 phthalate esters to representative aquatic organisms
Authors: Adams William J. , Biddinger Gregory R. , Robillard Kenneth A. , Gorsuch Joseph W.
Published: March 2010

Acute aquatic toxicity studies were performed with 14 commercial phthalate esters and representative freshwater and marine species. The 14 esters were dimethyl phthalate; diethyl phthalate; di-n-butyl phthalate; butyl benzyl phthalate; dihexyl phthalate; butyl 2-ethylhexyl phthalate; di-(n-hexyl, n-octyl, n-decyl) phthalate; di-(2-ethylhexyl) phthalate; diisooctyl phthalate; diisononyl phthalate; di-(heptyl, nonyl, undecyl) phthalate; diisodecyl phthalate; diundecyl phthalate; and ditridecyl phthalate. Phthalate esters with alkyl chain lengths of four carbon atoms or fewer were determined to be acutely toxic at concentrations ranging from 0.21 to 377 mg/L depending on the ester and the solubility of the test chemical in water. There was a general trend for the lower-molecular-weight phthalate esters (C1 to C4 alkyl chain lengths: dimethyl phthalate; diethyl phthalate; di-n-butyl phthalate; and butyl benzyl phthalate) to become more toxic with decreasing water solubility for all species tested. There were only minor differences in species sensitivity to each of the phthalate esters. Phthalate esters with alkyl chain lengths of six carbon atoms or more were not acutely toxic at concentrations approaching their respective aqueous solubilities. Insufficient mortality occurred to calculate either LC50 or EC50 values or acute no-observed-effect concentrations for these higher-molecular-weight phthalate esters. The lack of toxicity observed for the higher-molecular-weight phthalate esters resulted from their limited water solubility (≤1.1 mg/L).
Polychlorinated biphenyls (PCBs) depress allogeneic natural cytotoxicity by earthworm coelomocytes
Authors: Suzuki Michael M. , Cooper Edwin L. , Eyambe George S. , Goven Arthur J. , Fitzpatrick Lloyd C. , Venables Barney J.
Published: March 2010

Coelomocytes of the earthworm Lumbricus terrestris caused significant spontaneous allogeneic cytotoxicity in a 24-h trypan blue assay, but not in an assay using lactate dehydrogenase (LDH) release. Allogeneic cytotoxicity assays using cells from worms exposed to polychlorinated biphenyls (PCBs) suggest that PCBs can suppress a natural killing (NK-like) reaction. The implications of this work are twofold: understanding the evolution of natural killing (NK-like) activity and providing preliminary information on how spontaneous killing, a component of cellular immunity, may be compromised by pollutants.
Synergistic effect of flyash and SO2 on development of cucumber (Cucumis sativus L.) leaf injury
Authors: Tung Gabrielle , McIlveen William D. , Jones Randall D.
Published: March 2010

In a two-factorial experiment, sulfur dioxide alone at concentration of 131 μg/m3 over long exposures or flyash from either coal or oil combustion alone applied onto cucumber (Cucumis sativus L.) foliage causes no visible injury. However, if both flyash and sulfur dioxide were presented simultaneously, a specific mosaic-chlorosis symptom developed on leaves. A synergistic effect was thus demonstrated. Histopathology of the mosaic-chlorosis symptom was studied. An unusual pattern of tissue abnormally initiated from the collapse of the anticlinal cell walls of the upper epidermal cells and progressed along cell walls into mesophyll tissues. Cellular injury at the lower spongy tissues typical of that caused by SO2 was also observed. A significant elevation of sulfate-sulfur in the leaves treated with a combination of SO2 and flyash was demonstrated. Significant interactions between the two factors were found for both injury and sulfur chemistry. This suggests that flyash deposits on the leaf surface play a catalytic role in oxidizing atmospheric sulfur dioxide continuously to form sulfuric acid (H2SO4) in situ. This acid could infiltrate into mesophyll damage cells and tissues en route.
Evaluation of lipid-containing semipermeable membrane devices for monitoring organochlorine contaminants in the Upper Mississippi river
Authors: Ellis Geoffrey S. , Rostad Colleen E. , Huckins James N. , Schmitt Christopher J. , Petty Jimmie D. , Maccarthy Patrick
Published: March 2010

Organochlorine contaminants sequestered in lipid-containing semipermeable membrane devices (SPMDs) were compared to those found in tangential-flow ultrafilter permeates as part of a pilot study at 10 sites in the Upper Mississippi River system. Caged and feral fish from three primary sites were also analyzed for comparison. Concentrated organochlorine (OC) compounds were readily extracted from the SPMDs by dialysis into hexane, and samples were analyzed by gas chromatography-negative chemical ionization-mass spectrometry. Fish and water samples were processed by conventional methods. Reasonable agreement was found between analyte SPMD-derived water concentrations and measured values of ultrafilter permeates; however, concentrations of the same analytes in caged fish did not appear to be proportional to water concentrations derived from SPMDs and ultrafilter permeates. The greatest number of OC compounds was detected in SPMDs; fewer were detected in caged fish and feral fish.
Comparative fate of [14C]trichloroethylene in the root zone of plants from a former solvent disposal site
Authors: Anderson Todd A. , Walton Barbara T.
Published: March 2010

A comparison of the environmental fate of [14C]trichloroethylene ([14C]TCE) in vegetated and nonvegetated soils from a contaminated field site indicated increased mineralization (14CO2 production) in soils containing vegetation. Mineralization in soils containing Lespedeza cuneata (Dumont), Pinus taeda (L.), Solidago sp. (all collected from a former chlorinated solvent disposal site), and Glycine max, germinated from commercially available seeds, accounted for >26% of the total recovered radioactivity compared with approximately 15% for nonvegetated soil and <9% for control (sterile) soil. Uptake of 14C into plant tissues ranged from 1 to 21% total for leaves (or needles), stems, and roots and appeared to be related to plant species and water use during the experiment. The higher mineralization rates for [14C]TCE in the vegetated soils compared with nonvegetated soils indicates that the rhizosphere provides a favorable environment for microbial degradation of organic compounds. Therefore, vegetation may play an important role in enhancing biological remediation of contaminated surface soils in situ.