bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative toxicant sensitivity of sexual and asexual reproduction in the rotifer Brachionus calyciflorus
Authors: Snell Terry W. , Carmona Maria Jose 
Published: March 2010

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
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

Abstract
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

Abstract
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

Abstract
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.