bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation of chlorinated benzoic acid mixtures by plant–bacteria associations
Authors: Siciliano Steven D , Germida James J
Published: March 2010

Phytoremediation technologies must tolerate and degrade mixtures of contaminants, as most contaminated sites contain mixtures of compounds. This study assessed the ability of plant–bacteria associations to degrade mixtures of mono- and dichlorinated benzoic acids. Sixteen forage grasses and combinations of these grasses with several bacterial inoculants were screened for growth in soil contaminated with various concentrations of mono- or dichlorinated benzoic acids. Dahurian wild rye (Elymus dauricus) inoculated with a combination of Pseudomonas aeruginosa strain R75 and Pseudomonas savastanoi strain CB35 reduced 3-chlorobenzoic acid (3CBA) levels in soil by 74% (i.e., 583 to 149 mg/kg). Meadow brome (Bromus biebersteinii) inoculated with Alcaligenes sp. strain BR60 reduced 2,3-dichlorobenzoic acid (23diCBA) levels in soil by 56% (i.e., 125 to 55 mg/kg). Altai wild rye (Elymus angitus) inoculated with strains R75 and CB35 reduced 2,5-dichlorobenzoic acid (25diCBA) levels in soil by 46% (i.e., 211 to 113 mg/kg). Two plant–bacteria associations and uninoculated Dahurian wild rye also degraded mixtures of 3CBA, 23diCBA, or 25diCBA. When 25diCBA was mixed with 23diCBA, uninoculated Dahurian wild rye reduced levels of 25diCBA in soil by 31% and reduced the levels of both 25diCBA and 3CBA by up to 64% when these two contaminants were present in a mixture. Similarly, meadow brome inoculated with BR60 reduced 23diCBA and 3CBA levels by up to 50%. Levels of all three chlorinated benzoic acids were reduced by 53 to 63% by Altai wild rye inoculated with strains R75 and CB35. Our results indicate that plant–bacteria associations can tolerate and degrade mixtures of contaminants in soil but that predictions about phytoremediation of mixed contaminants may not be straightforward.
Behavioral and histopathological effects of fluoranthene on bullfrog larvae (Rana catesbeiana)
Authors: Walker Sean E , Taylor Douglas H , Oris James T
Published: March 2010

The goals of this study were to use behavioral and histopathological endpoints to examine the sublethal effects of fluoranthene exposure in conjunction with solar ultraviolet radiation on bullfrog larvae. Exposure to fluoranthene and simulated solar ultraviolet radiation for 48 h caused a significant effect on locomotor behavior at 60 μg fluoranthene/L. At 96 h, however, hyperactivity was noted in the 40-μg fluoranthene/L exposure. The skin of bullfrog larvae was sensitive to the phototoxic effects of fluoranthene. Following exposure to sublethal levels of fluoranthene (10 μg fluoranthene/L) there were signs of necrosis as well as structural alterations in the skin when examined using light microscopy. Based on these results, the photoinduced toxicity of fluoranthene, and hence other phototoxic polycyclic aromatic hydrocarbons, pose a potential hazard to ranid larvae well within the water solubility limits of the compound.
Vertical distribution of acid-volatile sulfide and simultaneously extracted metals in a recent sedimentation area of the river Meuse in the Netherlands
Authors: van den Berg Gerard A , Loch J P Gustav , van der Heijdt Lambertus M , Zwolsman John J.G
Published: March 2010

The bioavailability of heavy metals in sediments may be strongly decreased by the presence of AVS (acid-volatile sulfide). In contaminated freshwater sediments, however, AVS levels may not be sufficiently high to scavenge all reactive heavy metals. In different seasons, the vertical distribution of AVS and SEM (simultaneously extracted metals) was studied in sediment cores of a recent sedimentation area of the river Meuse. In the suboxic layer of the sediments, the amount of AVS is always too low to bind all reactive metals as sulfides (SEM/AVS > 1). SEM/AVS decreases with depth in the sediments, going from ratios higher than one in the surface sediments to ratios on the order of one or even less than one at greater depths. This large vertical variation in AVS levels is attributed to diagenetic processes i.e., sulfide oxidation in the suboxic top layer and sulfate reduction in the underlying anoxic sediment layer. The depth of the boundary between the suboxic and the anoxic layer changes seasonally. An important implication of these findings is that SEM/AVS ratios in mixed homogenized sediment samples are generally not suited for the assessment of potential metal toxicity of sediments.
Polycyclic aromatic hydrocarbons in sediments and mussels of the western Mediterranean sea
Authors: Baumard Pascale , Budzinski Hélène , Garrigues Philippe
Published: March 2010

The distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in superficial sediments and mussels (Mytilus galloprovincialis) of the western Mediterranean sea (French Riviera, Corsica, Sardinia). The analyses were performed by gas chromatography coupled to mass spectrometry (GC-MS). The PAH concentrations ranged from 1 to 20,500 ng/g in the sediments. Different molecular indices allowed differentiation between the different pollutant sources. On the French coast, PAHs originated mainly from incomplete combustion of organic matter (pyrolytic origin), whereas for some sites in Corsica and Sardinia an overimposition of petrogenic PAHs occurred. The mussel PAH concentrations ranged from 25 to 390 ng/g. The total and individual PAH bioaccumulation factors were calculated. The correlation between sediment and mussel PAH content was discussed in terms of bioavailability. It was possible to distinguish different absorption routes for the xenobiotics according to their physicochemical properties. Because the mussel distribution of phenanthrene and anthracene seems to be governed by their water solubility, these compounds were probably mainly absorbed as the water-dissolved form, whereas the heavier molecular weight PAHs (more than four aromatic rings), whose sediment and mussel concentrations are correlated with higher correlation coefficients than for phenanthrene and anthracene, were probably mainly absorbed as adsorbed on particles. Furthermore, a possible preferential biotransformation of benzo[a]pyrene over benzo[e]pyrene is discussed.
Degradation of tetraethyllead during the degradation of leaded gasoline hydrocarbons in soil
Authors: Mulroy Patrick T , Ou Li-Tse
Published: March 2010

For over 50 years, leaded gasoline was the only fuel for automobiles, and tetraethyllead (TEL) was the major octane number enhancer used in leaded gasoline. Ample information is available on the fate and remediation of gasoline hydrocarbons in contaminated subsoils and groundwater. However, little is known regarding the fate of TEL in leaded gasoline-contaminated subsoils and groundwater. In soil not contaminated with gasoline, TEL was rapidly degraded and completely disappeared in 14 d. In gasoline-contaminated soil, TEL degradation was slower; after 77 d, 4 to 17% of the applied TEL still remained in the contaminated soil. Disappearance of total petroleum hydrocarbons (TPH) was initially rapid but slowed appreciably after 7 to 14 d. As a result, after 77 d, 33 to 51% of the applied gasoline still remained in soil. The retardation of TEL degradation in leaded gasoline-contaminated soil is due to the presence of gasoline hydrocarbons. As long as gasoline hydrocarbons remain in soil, TEL may also remain in soil, most likely in the gasoline hydrocarbon phase.
Interference in fluorometric hydrogen peroxide determination using scopoletin–horseradish peroxidase
Authors: Donahue William F
Published: March 2010

Interference in fluorometric hydrogen peroxide (H2O2) determinations was investigated and attributed to exposure of the fluorophore scopoletin to visible light before the determination sequence. The combination of photobleaching and complex fluorometric properties of scopoletin results in unpredictable changes in its fluorescence unless the scopoletin is shielded from all excitation wavelengths for at least 3 min before determination. Addition of the enzyme horseradish peroxidase (HRP) to scopoletin solutions also causes dramatic decreases in solution fluorescence in the absence of H2O2. Use of a series of standard solutions of scopoletin, HRP, and H2O2 that are shielded for 3 min before independent measurement of fluorescence is suggested for calibration to eliminate these problems in determination of nanomolar concentrations of H2O2.
Lipid methodology and pollutant normalization relationships for neutral nonpolar organic pollutants
Authors: Randall Robert C , Young David R , Lee Henry , Echols Scott F
Published: March 2010

This work compares the ability of hexane and chloroform with methanol (C/M) to extract lipid, polychlorinated biphenyls (PCBs), and p,p′-DDE from white croaker (Geneonus lineatus) muscle tissue. Hexane extracted on average 25% of the lipid and 73% of the PCB congeners that were extracted by C/M. Both solvents extracted similar quantities of p,p′-DDE. Consequently, PCB and p,p′-DDE lipid-normalized concentrations using hexane values were 2.9 and 3.9 times greater than with C/M values, and greater than fivefold differences are possible using hexane lipid values with C/M pollutant values. Because the solvents primarily extract different lipid pools, the results conceivably approximate the largest lipid-normalized pollutant concentration differences obtainable using common solvents. The differences suggest that lipid-normalized pollutant concentrations in fish muscle tissue will vary among studies without a standardized total lipid method, but more research is required to better identify complex neutral pollutant and lipid relationships before a final standard methodology can be selected. In the interim, we recommend that the Bligh-Dyer method with C/M be used to obtain total lipid for lipid-normalizing pollutant concentrations. If another solvent or system is used, the C/M extraction should be conducted on representative samples to allow for interconversion of lipid results.
Distribution, sources, and stability of haloacetic acids in Tokyo Bay, Japan
Authors: Hashimoto Shinya , Azuma Tadashi , Otsuki Akira
Published: March 2010

The distribution and sources of haloacetic acids in seawater in the vicinity of Tokyo Bay, Japan, were investigated, in view of the potential toxicity of these compounds to aquatic organisms. Haloacetic acids were extracted from water samples collected at 66 sampling stations (n = 122). Concentrations of all nine haloacetic acids containing bromine and chlorine were determined by liquid chromatography–mass spectrometry. We found that concentrations of trichloroacetic acid (TCAA) were high (maximum: 20.3 μg/L) compared to those of the other haloacetic acids in coastal seawater. The distributions and relative concentrations of TCAA and other haloacetic acids (monochloroacetic acid, dichloroacetic acid, and bromochloroacetic acid) suggest that their sources are not identical; discharge of wastewaters containing TCAA in the bay area is probably one of the main sources of the observed high concentrations of TCAA in seawater there. The mean concentrations of haloacetic acids in water samples and the results of incubation experiments of haloacetic acids in river water and seawater suggest that TCAA is relatively stable in the aquatic environment.
Distribution of uranium-238 in environmental samples from a residential area impacted by mining and milling activities
Authors: McConnell Marc A , Ramanujam V M Sadagopa , Alcock Nancy W , Gabehart Gary J , Au William W
Published: March 2010

The northern region of Karnes County, Texas, USA, has been the site of extensive mining/milling of uranium for over 30 years. A previous study in our laboratory indicates that residents living near these facilities have increased chromosomal aberrations and a reduced DNA repair capacity. In this study, the long-lived radionuclides uranium-238 (238U) and thorium-232 (232Th) were measured in order to evaluate the extent of contamination from mining/milling facilities. 232Th was quantified simultaneously and served as a reference. Soil samples (n = 70) were collected from the yards of previously studied households and adjacent areas near former mining and mining/milling sites at the surface and 30 cm subsurface. Additionally, samples from drinking water wells (n = 6) were collected from selected households. Sites located over 14 km from the study area with no known history of mining/milling served as the control. In the control area, 238U concentrations in soil were consistent between surface (0.13–0.26 mg/kg) and subsurface (0.13–0.23 mg/kg) samples. Near mining/milling sites, 238U in surface soil (0.34–15.71 mg/kg) was found to be consistently and statistically higher (p < 0.05) than corresponding subsurface samples (0.17–2.11 mg/kg). Near mining-only areas, 238U in surface soil (1.11–1.97 mg/kg), however, was not significantly increased over subsurface soil (0.96–1.68 mg/kg). As expected, 238U was much higher overall in the mining/milling and mining-only areas compared to the control sites. No trends were detected in the distribution of 232Th. The concentration of 238U was up to six times higher in a drinking water well near a former mining/milling operation, indicating possible leaching into the groundwater, while 232Th concentrations were low and uniform. Furthermore, lead isotope ratio analysis indicates contamination from the interstate shipping of ore by rail to and from a mining/milling facility. These data indicate contamination of the environment by the mining/milling activities in a residential area.
Concomitant aerobic biodegradation of benzene and thiophene
Authors: Dyreborg Søren , Arvin Erik , Broholm Kim
Published: March 2010

The concomitant aerobic biodegradation of benzene and thiophene was investigated in microcosm experiments using a groundwater enrichment culture. Benzene was biodegraded within 1 d, whereas thiophene could not be biodegraded as the sole source of carbon and energy. Some interesting phenomena were observed when both benzene and thiophene were present. In most cases, removal of thiophene was observed, and the removal occurred concomitantly with the biodegradation of benzene, suggesting that benzene was used as a primary substrate in the cometabolic biodegradation of thiophene. No biodegradation of the two compounds was observed for some combinations of concentrations, suggesting that thiophene could act as an inhibitor to benzene biodegradation. However, this effect could be overcome if more benzene was added to the microcosm. Residual concentrations of benzene and thiophene were observed in some microcosms and the data indicated that the biodegradation of the two compounds stopped when a critical threshold ratio between the concentrations of thiophene and benzene was reached. This ratio varied between 10 and 20. Results from modeling the biodegradation data suggested that thiophene was cometabolized concomitantly with the biodegradation of benzene and that the biodegradation may be described by a modified model based on a traditional model with an inhibition term incorporated.
Changes in metallothionein mRNA and protein after sublethal exposure to arsenite and cadmium chloride in juvenile winter flounder
Authors: Jessen-Eller Kathy , Crivello Joseph F
Published: March 2010

Juvenile winter flounder (Pleuronectes americanus) from a Long Island Sound site within the Niantic River region contain elevated levels of liver As and Cd. Previous work in mammals suggests that a reduced species of As, NaAs3+, is as potent a metallothionein (MT) inducer as CdCl2. We investigated whether this is also the case in winter flounder by subcutaneously exposing juveniles to a sublethal range of NaAs3+ (0, 0.38, 0.75, and 1.5 μmol/g fish) or CdCl2 (0, 0.045, 0.09, and 0.18 μmol/g fish). Of the two, CdCl2 was the more potent MT inducer, with an 8-fold lower molar equivalent causing a 3-fold higher response. Both metals rapidly induced MT protein within 24 h of exposure, but only the highest dose of CdCl2 elicited a significant increase in MT mRNA. The magnitude of the MT protein response to CdCl2 (7.25-fold) demonstrates that elevated liver As and Cd do not narrow the MT response window in juvenile flounder from the Niantic River region. These fish have relatively low liver MT protein levels (46 μg/g) and will be a useful reference population for future metal impact studies within Long Island Sound.
Combined effects of copper, desiccation, and frost on the viability of earthworm cocoons
Authors: Holmstrup Martin , Petersen Birgitte Friis , Larsen Martin Mørk
Published: March 2010

The effects of heavy metal pollution on earthworms have been extensively studied, but no studies have examined how earthworms react if they are simultaneously exposed to metal pollution and climatic stress. This question has been addressed in a laboratory study where cocoons of Aporrectodea caliginosa and Dendrobaena octaedra were initially exposed to copper in aqueous solutions of copper chloride and thereafter exposed to realistic degrees of either desiccation or frost. Earthworm embryos absorbed copper in amounts (up to approx. 200 mg/kg dry tissue weight) comparable to concentrations found in various tissues of earthworms from metal-polluted soils. Desiccation and copper exposure in combination had synergistic effects on survival rates for both species. For example, at full saturation, the NOEC (the highest tested concentration with no statistically significant effect) for copper of A. caliginosa was 12 mg/L, whereas at 97% relative humidity it was only 6 mg/L. Frost and copper exposure in combination also showed synergistic effects in some experiments. No cocoons of A. caliginosa exposed to 20 mg copper/L were viable after exposure to −3°C but at 0°C viability was as high as 95%. The same tendency was seen in D. octaedra but not as clearly as in A. caliginosa. A change of the environmental conditions (moisture, temperature) to increasing severity caused a shift in the statistically derived NOEC toward lower critical values of copper. The involvement of combination effects in ecotoxicological tests could therefore improve risk assessment of soil-polluting compounds.
Development and application of a marine sediment pore-water toxicity test using Ulva fasciata zoospores
Authors: Hooten Russell L , Carr R Scott
Published: March 2010

An acute (96 h) pore-water toxicity test protocol using germination and growth of Ulva fasciata zoospores as endpoints was developed to test the toxicity of marine and estuarine sediment pore-water samples. Tests with an organic toxicant (sodium dodecyl sulfate; SDS), three metals (Cd, Cu, and Zn), and ammonia (NH3) were conducted to determine zoospore sensitivity. Zoospore germination and gametophyte growth were as sensitive to SDS as sea urchin (Arbacia punctulata) fertilization and embryological development. Zoospore sensitivity to metals was greater than or comparable to that of adult macroalgae. Zoospores were less sensitive to NH3 than were other commonly used toxicity test organisms. Test results using this algal assay with sediment pore-water samples with high NH3 concentrations were compared with results from sea urchin fertilization and embryological development tests for the same samples. Ulva fasciata zoospore germination was not affected by samples with high NH3 concentrations that were toxic in both sea urchin tests. Zoospore tolerance of NH3 and sensitivity to other contaminants indicate that their response may be useful in toxicity identification evaluation studies with pore-water samples that contain high concentrations of unionized NH3.
Identification of chloro-nitro-trifluoromethyl-substituted dibenzo-p-dioxins in lampricide formulations of 3-trifluoromethyl-4-nitrophenol: Assessment to induce mixed function oxidase activity
Authors: Hewitt L Mark , Carey John H , Munkittrick Kelly R , Parrott Joanne L , Solomon Keith R , Servos Mark R
Published: March 2010

The contamination of field formulations of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) bya dibenzo-p-dioxin containing -chloro, -nitro, and -trifluoromethyl substituents was suspected from chemical fractionations of a TFM formulation that were directed by mixed function oxidase (MFO) induction in rainbow trout. Three dioxin isomers containing these substituents in field formulations were identified by gas chromatography–mass spectrometry (GC-MS). Short-term waterborne exposures to a mixture of two isomers, 2-trifluoromethyl-3-nitro-7- (and 8)-chloro-dibenzo-p-dioxin, elevated MFO activity in trout, with a threshold between 0.148 and 0.745 nM (4.1–20.5 ng/L). Synthetic preparations of other dioxins related to formulation impurities enabled characterizations of this previously unknown family of dioxin congeners by GC-MS. The elution order of the isomers followed those established for halogenated dioxins except where there was a lone -nitro substitution on one ring. The average concentration of these compounds in TFM formulations spanning more than a decade was 288 ± 47 μg/L, which translates into an annual loading of approximately 40 g to the Great Lakes Basin. Using mammalian (H4IIE) and fish (PLHC-1) in vitro assays, a 2,3,7-substituted chloro-nitro-trifluoromethyl isomer was a four to five times more potent inducer of MFO activity than 2,3,7-trichlorodibenzo-p-dioxin. Characterizations of the synthetic isomers indicate that the isomers present in the formulation are not substituted in the 2,3,7- positions and are relatively weak inducers of MFO activity.
Bioconcentration of gaseous organic chemicals in plant leaves: Comparison of experimental data with model predictions
Authors: Polder Marieke D , Hulzebos Etje M , Jager D Tjalling
Published: March 2010

This literature study is performed to support the implementation of two models in a risk assessment system for the evaluation of chemicals and their risk for human health and the environment (Uniform System for the Evaluation of Substances [USES] 1.0). One of the exposure pathways for humans and cattle is the uptake of chemicals by plants. In this risk assessment system the transfer of gaseous organic substances from air to plants modeled by Riederer is included. A similar model with a more refined approach, including dilution by growth, is proposed by Trapp and Matthies, which was implemented in the European version of this risk assessment system (EUSES). In this study both models are evaluated by comparison with experimental data on leaf/air partition coefficients (bioconcentration factors [BCFs]) found in the literature. For herbaceous plants both models give good estimations for the leaf/air partition coefficient up to 107, with deviations for most substances within a factor of five. For the azalea and spruce group the fit between experimental BCF values and the calculated model values is less adequate. For substances for which Riederer estimates a leaf/air partition coefficient above 107, the approach of Trapp and Matthies seems more adequate; however, few data were available.
An inexpensive and efficient modular water-renewal system for bulk sediment toxicity testing
Authors: Leppanen Christy J , Maier Kurt J
Published: March 2010

Recently developed test guidance for conducting whole-sediment toxicity tests with aquatic invertebrates requires exchange of overlying water to maintain acceptable water quality. Described here is an accurate and consistent modular water-renewal system (delivering 150 ± 5 ml renewal water) and containment chamber for bulk sediment toxicity tests. The system can be customized to meet testing demands by adding multiple units. Each unit can hold up to 49 300-ml beakers. Construction is simple (<4 h/unit) and inexpensive (< $90/unit). This system has been used successfully in 10-d whole-sediment toxicity tests with Chironomus tentans and Hyalella azteca.
Predicting the toxicity of sediment-associated trace metals with simultaneously extracted trace metal: Acid-volatile sulfide concentrations and dry weight-normalized concentrations: A critical comparison
Authors: Long Edward R , MacDonald Donald D , Cubbage James C , Ingersoll Chris G
Published: March 2010

The relative abilities of sediment concentrations of simultaneously extracted trace metal: acid-volatile sulfide (SEM: AVS) and dry weight-normalized trace metals to correctly predict both toxicity and nontoxicity were compared by analysis of 77 field-collected samples. Relative to the SEM:AVS concentrations, sediment guidelines based upon dry weight-normalized concentrations were equally or slightly more accurate in predicting both nontoxic and toxic results in laboratory tests.
Estimating impact of humic acid on bioavailability and bioaccumulation of hydrophobic chemicals in guppies using kinetic solid-phase extraction
Authors: Freidig Andreas P , Garicano Elsa Artola , Busser Frans J M , Hermens Joop L M
Published: March 2010

Many organic micropollutants show a reduced bioavailability in the presence of dissolved organic matter, which is explained by reduction of the freely dissolved aqueous concentration. The partition coefficient between organic matter and the aqueous phase, KDOC, is used to describe the distribution of neutral hydrophobic micropollutants. In the present study, the freely dissolved concentration was measured using partitioning of micropollutants between water and a hydrophobic solid-phase filter disk (C-18 Empore™ disk). Slivers of the disk were exposed in aqueous solutions that contained several micropollutants and Aldrich humic acid at different concentrations. Initial uptake rates of the micropollutants from water to disk (k1) were measured to estimate the freely dissolved concentration in the solution. Partition coefficients, KDOC, of tetra- and hexachlorobenzene, pentachloroaniline, iodofenphos, and p,p′ DDT were calculated. These values were comparable to earlier, published KDOCs toward Aldrich humic acid. In a validation experiment, the uptake rates of three chlorobenzenes in guppy (Poecilia reticulata) were measured in the absence and presence of humic acids. The lowering of the uptake rates in guppy was correctly predicted with the KDOC values from the Empore disk experiment. These findings suggest that the proposed method to measure the freely dissolved concentration is a valid tool to predict the bioavailability of hydrophobic compounds in the aqueous environment.
Application of toxicity-based fractionation techniques and structure-activity relationship models for the identification of phototoxic polycyclic aromatic hydrocarbons in sediment pore water
Authors: Kosian Patricia A , Makynen Elizabeth A , Monson Philip D , Mount David R , Spacie Ann , Mekenyan Ovanes G , Ankley Gerald T
Published: March 2010

Recent studies conducted at our laboratory have shown that sediments contaminated with complex mixtures of polycyclic aromatic hydrocarbons (PAHs) can exhibit enhanced toxicity (lethality) to a variety of aquatic species when the samples are tested under ultraviolet (UV) light designed to mimic the wavelengths present in sunlight. However, because these contaminated sediments can contain literally thousands of chemicals, it is difficult to use conventional analytical techniques to identify those compounds responsible for photo-induced toxicity. The purpose of this study was to adapt existing toxicity identification evaluation methods to attempt to identify those compounds contributing to the phototoxicity observed in our sediment samples. Pore water obtained from sediments collected near an oil refinery discharge was toxic to Lumbriculus variegatus following exposure to UV light, while organisms exposed to the same pore water, but without subsequent UV treatment, showed no toxic effect. Solid-phase extraction disks and high-performance liquid chromatography were used, in conjunction with toxicity tests with L. variegatus, to extract and fractionate phototoxic chemicals from the pore water. Phototoxic fractions analyzed by gas chromatography–mass spectrometry revealed the presence of a number of aliphatic hydrocarbons, substituted PAHs, and PAHs containing heteroatoms. Chemicals were screened for their phototoxic potential based on empirical data and predictive models. A refined list of PAHs was then evaluated on the basis of their phototoxic potency as defined by a recently developed quantitative structure–activity relationship model and estimates of their bioaccumulation potential. Based on the model predictions of potency and bioaccumulation, nine likely phototoxic chemicals were identified.
Use of a lux-modified bacterial biosensor to identify constraints to bioremediation of btex-contaminated sites
Authors: Sousa Sofia , Duffy Catherine , Weitz Hedda , Glover L Anne , Bär Eckart , Henkler Rolf , Killham Ken
Published: March 2010

Sediment and groundwater samples obtained from a benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated site were screened, using a bioluminescence-based (lux gene-marked) bacterial biosensor, to identify constraints to site remediation. Through a series of sample manipulations and linked biosensor responses, constraints to BTEX remediation such as adverse pH, presence of nonvolatile organic contaminants, and the presence of heavy metals were investigated. Conventional chemical analysis (gas chromatography, inductively coupled plasma mass spectroscopy) was used to confirm the reliable performance of the biosensor and to identify its potential contribution to site management to ensure effective remediation. The toxicity results of the biosensor were expressed in % maximum bioluminescence calculated against a blank of double deionized water with pH adjusted to 5.5. Untreated samples caused reductions in percentage bioluminescence from 10 to 95%. Water sample W1, containing a total BTEX concentration of 30,595 μg/L caused the highest decrease in bioluminescence (5.78%). This toxicity was significantly reduced after elimination of volatile organic compounds (VOCs) (42.01%) and bioluminescence was further increased to 87.80% after removal of total organic matter. This suggested that VOCs were not the only toxic organopollutants present. Water samples giving high values of bioluminescence contained BTEX concentrations of 17 to 31 μg/L.
A comparative study of molecular similarity, statistical, and neural methods for predicting toxic modes of action
Authors: Basak Subhash C , Grunwald Gregory D , Host George E , Niemi Gerald J , Bradbury Steven P
Published: March 2010

Quantitative structure–activity relationship (QSAR) models are routinely used in predicting toxicologic and ecotoxicologic effects of untested chemicals. One critical factor in QSAR-based risk assessment is the proper assignment of a chemical to a mode of action and associated QSAR. In this paper, we used molecular similarity, neural networks, and discriminant analysis methods to predict acute toxic modes of action for a set of 283 chemicals. The majority of these molecules had been previously determined through toxicodynamic studies in fish to be narcotics (two classes), electrophiles/proelectrophiles, uncouplers of oxidative phosphorylation, acetylcholinesterase inhibitors, and neurotoxicants. Nonempirical parameters, such as topological indices and atom pairs, were used as structural descriptors for the development of similarity-based, statistical, and neural network models. Rates of correct classification ranged from 65 to 95% for these 283 chemicals.
Inhibition of sex pheromone communications of Trichogramma brassicae (Hymenoptera) by the insecticide chlorpyrifos
Authors: Delpuech Jean-Marie , Froment Benoit , Fouillet Pierre , Pompanon François , Janillon Sonia , Boulétreau Michel
Published: March 2010

Biological control agents such as entomophagus insects (e.g., Trichogramma sp.) are important components of integrated pest management (IPM) programs. Because pesticides are also an important component of IPM programs, it is essential to understand how biological control agents are affected by pesticides and how these effects may affect the effectiveness of the biological control agents. Contrary to most insect species that use volatile pheromones for mate location, T. brassicae is one of the few species using a substrate-borne sex pheromone for mating. In this work we determined the effects of an organophosphorus insecticide, chlorpyrifos, on sex pheromone reception by males and emission by virgin females. The insects used in the pheromone tests were survivors from an acute toxicity test in which individuals were exposed to a dose of chlorpyrifos equivalent to a 20% lethal dose. Males that survived the insecticide exposure spent much less time on the area marked with the female pheromone than control males (mean choice indexes, 0.46 [0.34 SD] vs 0.70 [0.25 SD], p < 0.001). The kinetics of the response of males to marking by control and treated females indicated that chlorpyrifos decreased the emission of sex pheromone by females surviving the insecticide. Therefore, chlorpyrifos inhibited pheromone reception by males and decreased pheromone emission by virgin females. These results are interpreted in the context of sex pheromone regulation by the nervous system of insects and according to the mode of action of chlorpyrifos. Extensions of these results on actual work on sex pheromone, the use of pheromone traps, and the population biology of Trichogramma sp. are discussed.
Edaphic factors affecting the toxicity and accumulation of arsenate in the earthworm Lumbricus terrestris
Authors: Meharg Andrew A , Shore Richard F , Broadgate Kirsten
Published: March 2010

The toxicity and accumulation of arsenate was determined in the earthworm Lumbricus terrestris in soil from different layers of a forest profile. Toxicity increased fourfold between 2 and 10 d. Edaphic factors (pH, soil organic matter, and depth in soil profile) also affected toxicity with a three fold decrease in the concentration that causes 50% mortality with increasing depth in soil (from 0–70 mm to 500–700 mm). In a 4-d exposure study, there was no evidence of arsenic bioconcentration in earthworm tissue, although bioaccumulation was occurring. There was a considerable difference in tissue residues between living and dead earthworms, with dead worms having higher concentrations. This difference was dependent on both soil arsenate concentration and on soil type. Over a wide range of soil arsenate concentrations, earthworm arsenic residues are homeostatically maintained in living worms, but this homeostasis breaks down during death. Alternatively, equilibration with soil residues may occur via accumulation after death. In long-term accumulation studies in soils dosed with a sublethal arsenate concentration (40 μg/g dry weight), bioconcentration of arsenate did not occur until day 12, after which earthworm concentrations rose steadily above the soil concentration, with residues in worms three fold higher than soil concentrations by the termination of the study (23 d). This bioconcentration only occurred in depurated worms over the time period of the study. Initially, depurated worms had lower arsenic concentrations than undepurated until tissue concentrations were equivalent to the soil concentration. Once tissue concentration was greater than soil concentration, depurated worms had higher arsenic residues than undepurated.
Experimental oiling of sanderlings (Calidris alba): Behavior and weight changes
Authors: Burger Joanna , Tsipoura Nellie
Published: March 2010

We applied fresh and weathered oil from the Anitra oil spill to the belly feathers of experimental sanderlings (Calidris alba) to simulate 20% plumage oiling, whereas controls were stroked with clean swabs only. We tested the null hypotheses that there were no differences in behavior following oiling and that there were no differences in weight gain or loss in control and experimental birds. Control sanderlings showed no differences in behavior before and after oiling, but oiled birds spent significantly less time resting and more time bathing and preening. Significant differences in weight and behavior were observed between the control and oiled birds. Following oiling, the sanderlings preened vigorously, spreading the oil so that they appeared to have oiling rates of 30%. Thereafter, the percentage of their plumage that was oiled decreased steadily over the next 2 weeks, but the birds never appeared completely free of oil.
Longevity and reproduction ofCeriodaphnia dubiain receiving waters
Authors: Stewart Arthur J , Konetsky Belinda K
Published: March 2010

Seven-day tests with Ceriodaphnia dubia are commonly used to estimate toxicity of effluents or receiving waters but can sometimes yield no toxicity outcomes even if pollutants are present. We conducted two sets of full life-cycle tests with C. dubia to (1) determine whether tests with longer exposure periods to low concentrations of contaminants in ambient water might reveal evidence of toxicity that could not be discerned from 7-d tests and (2) determine the relative importance of water quality versus food as factors influencing C. dubia longevity and reproduction. In the first set of tests, C. dubia was reared in diluted mineral water (a negative control), water from a stream impacted by coal fly-ash, or water from a retention basin containing sediments contaminated with mercury, other metals, and polychlorinated biphenyls. The second set of tests used water from the retention basin only. Before testing, though, water in the second set of tests was either filtered or not filtered, and food was either added or not added. Ceriodaphnia dubia longevity and reproduction did not differ much among the three water types in the first set of tests, but both longevity and reproduction were strongly affected by the filtering and food-addition treatments in the second set of tests. Thus, C. dubia appeared to be relatively insensitive to general water quality factors but sensitive to food-related factors. In five of the six full life-cycle tests, lifetime reproduction by C. dubia could not be reliably predicted from reproduction data from the first 7 d of testing (R2 < 0.35, by regression analysis). The increase in predictability of lifetime reproduction of C. dubia as a function of test duration also differed among water types in the first set of tests and among treatments in the second set of tests. Thus, it may not be possible to reliably extrapolate the results of 7-d tests with C. dubia to longer time scales.
Toxicity effects of organosulfur compounds on anaerobic microbial metabolism
Authors: Londry Kathleen L , Suflita Joseph M.
Published: March 2010

Four classes of organosulfur compounds were tested for their effects on anaerobic microbial activity as indicated by rates of lactate degradation, nitrate or sulfate reduction, and methanogenesis. Each class consisted of five to eight chemically related compounds that were added concurrently to anaerobic cultures established with an oily sludge inoculum. Effects on anaerobic activities were evaluated at different amounts of the chemicals and were concentration dependent in all cases. Thiophenes and thiols inhibited microbial activity under methanogenic conditions at ≥5 mmol/L; the former compounds had less effect under nitrate-reducing conditions, and the latter had less effect under sulfate-reducing conditions. Thiophenic acids did not influence most microbial processes at the lower concentrations tested (≤0.50 mmol/L). Aromatic sulfides were inhibitory to microbial activity under all three conditions at ≥5 mmol/L and had a greater effect on electron acceptor reduction than lactate oxidation. We conclude that the inhibitory effect of organosulfur compounds on microbial metabolism could potentially influence the assessment of anaerobic biodegradation activities in either the laboratory or anoxic environments.
Use of quantitative shape-activity relationships to model the photoinduced toxicity of polycyclic aromatic hydrocarbons: Electron density shape features accurately predict toxicity
Authors: Mezey Paul G , Zimpel Zbigniew , Warburton Peter , Walker P Duane , Irvine Donald G , Huang Xiag-Dong , Dixon D George , Greenberg Bruce M
Published: March 2010

The quantitative shape–activity relationship (QShAR) methodology, based on accurate three-dimensional electron densities and detailed shape analysis methods, has been applied to a Lemna gibba photoinduced toxicity data set of 16 polycyclic aromatic hydrocarbon (PAH) molecules. In the first phase of our studies, a shape fragment QShAR database of PAHs was developed. The results provide a very good match to toxicity based on a combination of the local shape features of single rings in comparison to the central ring of anthracene and a more global shape feature involving larger molecular fragments. The local shape feature appears as a descriptor of the susceptibility of PAHs to photomodification and the global shape feature is probably related to photosensitization activity.
Bioavailability and biodegradation of weathered diesel fuel in aquifer material under denitrifying conditions
Authors: Bregnard Thierry Pierre-Alain , Höhener Patrick , Zeyer Josef
Published: March 2010

During the in situ bioremediation of a diesel fuel-contaminated aquifer in Menziken, Switzerland, aquifer material containing weathered diesel fuel (WDF) and indigenous microorganisms was excavated. This material was used to identify factors limiting WDF biodegradation under denitrifying conditions. Incubations of this material for 360 to 390 d under denitrifying conditions resulted in degradation of 23% of the WDF with concomitant consumption of NO 3− and production of inorganic carbon. The biodegradation of WDF and the rate of NO 3− consumption was stimulated by agitation of the microcosms. Biodegradation was not stimulated by the addition of a biosurfactant (rhamnolipids) or a synthetic surfactant (Triton X-100) at concentrations above their critical micelle concentrations. The rhamnolipids were biodegraded preferentially to WDF, whereas Triton X-100 was not degraded. Both surfactants reduced the surface tension of the growth medium from 72 to <35 dynes/cm and enhanced the apparent aqueous solubility of the model hydrocarbon n-hexadecane by four orders of magnitude. Solvent-extracted WDF, added at a concentration equal to that already present in the aquifer material, was also biodegraded by the microcosms, but not at a higher rate than the WDF already present in the material. The results show that the denitrifying biodegradation of WDF is not necessarily limited by bioavailability but rather by the inherent recalcitrance of WDF.
Distribution of alkylphenol compounds in great lakes sediments, United States and Canada
Authors: Bennett Erin R , Metcalfe Chris D
Published: March 2010

Alkylphenol polyethoxylates are a major class of nonionic surfactants that are microbially degraded in sewage treatment plants (STPs) and sediments to more toxic and hydrophobic alkylphenols. Recent data on the estrogenic activity of alkylphenols has prompted interest in the distribution of these compounds in the aquatic environment. Sediment samples were collected from several sites (n = 28) at industrialized and pristine regions of Lake Huron, Lake Erie, and Lake Ontario, USA and Canada, and analyzed for concentrations of 4-nonylphenol (NP) and 4-(tert)-octylphenol (OP). Also, sludge samples were taken from a secondary STP in Whitby, Ontario, Canada. Sediment and sludge samples and analytical standards were prepared for analysis by gas chromatography–mass spectrometry in selected ion mode by combined acetylation and supercritical fluid extraction. Concentrations of NP were up to 37 μg/g in sediments and >300 μg/g in the sewage sludge. Concentrations of OP were up to 23 μg/g in sediment and 21 μg/g in the sewage sludge. These data indicate that alkylphenols are distributed widely in sediments in the lower Great Lakes. However, concentrations of NP were present at high (μg/g) levels only in sediments near urban and industrialized centers.
Impact of glufosinate-ammonium and bialaphos on the phytoplankton community of a small eutrophic northern lake
Authors: Faber Marvin J , Thompson Dean G , Stephenson Gerald R , Boermans Herman J
Published: March 2010

The impact of glufosinate-ammonium and bialaphos on the phytoplankton community in a shallow eutrophic lake ecosystem was investigated using in situ enclosures. Flow cytometry was used to size phytoplankton cells and sort them as live or dead, depending upon their chlorophyll a autofluorescence intensity. Flow cytometric analyses provided significantly (p < 0.001) higher abundance estimates as compared to conventional microscopic analyses. At the highest treatment levels (10 mg/L), both herbicides caused a significant but transient reduction in live phytoplankton cells (days 3–14), which was particularly apparent in the small (1–2 and 2–3 μm) classes. Transient impacts on phytoplankton live cell abundances were mirrored by depression in dissolved oxygen content in the treated enclosures. At an application rate of 10 mg/L, abundance of smaller phytoplankton in the bialaphos-treated enclosures recovered more rapidly (14 d) than those in the glufosinate-ammonium–treated enclosures (49 d). For days of maximal impact, estimated median effect concentrations (EC50) for reduction of phytoplankton abundance ranged from 2.5 to 3.4 mg/L for glufosinate-ammonium and 3.3 to 8.1 mg/L for bialaphos, whereas estimates of concentration inducing 20% reductions in abundance (EC20; 0.9–1.2 and 1.6–4 mg/L, respectively) more closely approximated the expected environmental concentration (1 mg/L), assuming direct overspray into water bodies of 15-cm depth.
Age-dependent toxicity of diazinon and terbufos in european starlings (Sturnus vulgaris) and red-winged blackbirds (Agelaius phoeniceus)
Authors: Wolfe Marti F , Kendall Ronald J
Published: March 2010

Adult European starlings (Sturnus vulgaris) are more resistant to poisoning by organophosphorous (OP) pesticides than are other passerine birds. Nestling starlings, however, are sensitive to OP intoxication. Both adult and nestling red-winged blackbirds (Agelaius phoeniceus) are sensitive to OP toxicity and therefore may be a more representative model of the toxic response of passerine birds. The purpose of this study was to compare the toxicity ratio, as indicated by median lethal dose (LD50), of terbufos and diazinon in adult and nestling starlings and red-winged blackbirds, and to compare cholinesterase (ChE) inhibition between species and among age groups. Red-winged blackbirds are more sensitive to terbufos and diazinon intoxication than are European starlings, and the young of both species are more sensitive than the adults. When mortality is used as the endpoint, adult starlings are approximately 103 times less sensitive to terbufos intoxication than are 2-d-old starling chicks and 137 times less sensitive than adult red-wings. Adult red-wings were only 4.1 times less sensitive than 0 to 3-d-old red-wing chicks. Adult starlings were approximately 47 times less sensitive to diazinon toxicity than 2-d-old starling nestlings and 65 times less sensitive than adult redwings. Adult red-wings were 3.8 times less sensitive to diazinon than 0- to 3-d-old red-wing nestlings. Plasma and brain ChE activity was depressed in starling and red-wing adults in a dose-dependent fashion, but the relationship between dose, and plasma and brain ChE depression was more evident in some nestling age groups than in others. Baseline ChE activity cannot be invoked to explain the sensitivity difference between species. Baseline ChE activities in both brain and plasma increase with age in both species. These changes may account in part for the greater sensitivity of the young as compared to the adult.