bluuebunny/crossref_metadata_2025 huggingface dataset:
A modeling framework for exploring the population-level effects of endocrine disruptors
Authors: McTavish Kathleen , Stech Harlan , Stay Frank
Published: March 2010

Methods are proposed for modeling the population-level effects of endocrine-disrupting chemicals on age-structured populations. We present a framework for representing xenobiotic-induced impacts to reproductive, life-stage transition, and mortality rates. Numerical simulations are described addressing delayed disturbance and recovery dynamics and potential transgenerational effects.
Effects of waterborne mercury on terrestrial wildlife at clear lake: Evaluation and testing of a predictive model
Authors: Wolfe Marti , Norman Donald
Published: March 2010

Birds and mammals exposed to waterborne mercury (Hg) and methylmercury (MeHg) were collected and/or sampled at Clear Lake, California, USA, to field test the predictive wildlife criteria model developed for the Great Lakes Water Quality Initiative (GLWQI). Tissue samples collected from sampled animals were analyzed for Hg and organochlorine residues, and for selected physiologic parameters known to be affected by Hg. All mammalian organ tissues analyzed contained less than 12 ppm total Hg, wet weight. All avian tissue samples analyzed contained less than 3 ppm total Hg, wet weight. No evidence of Hg-associated health effects was found. Tissue Hg residues were compared with water, sediment, and animal food samples to characterize bioaccumulation of mercury in the Clear Lake food web. Total Hg bioaccumulation factors for the Clear Lake site closest to the Hg source were: TL-2: 11,100; TL-3: 31,200; TL-4, 190,000. Our results support the final wildlife criterion (1,300 pg/L) and suggest that the GLWQI model, with site-specific modifications, is predictive for other Hg-bearing aquatic systems.
Effect of nitrate-based bioremediation on contaminant distribution and sediment toxicity—column study
Authors: Hutchins Stephen R , Bantle John A , Schrock Elizabeth J
Published: March 2010

A laboratory column study was set up to evaluate changes in contaminant distribution and sediment toxicity following nitrate-based bioremediation and to correlate toxicity reduction with loss of fuel components. Glass columns were packed with sediment from an aquifer that had been contaminated with JP-4 jet fuel and were remediated using feed solution containing 20 mg/L NO3-N. Column influents and effluents were monitored for BTEXTMB (benzene, toluene, ethylbenzene, xylenes, trimethyl-benzenes), electron acceptors, nutrients, and dissolved gases. Duplicate columns were sacrificed after 1, 4, and 7 months, and core material was analyzed for chemical constituents. In addition, core material was evaluated for toxicity using FETAX, a developmental toxicity test employing frog embryos. After 1 month of operation, total mass of BTEXTMB dropped from 51.8 ± 7.3 mg to 29.8 ± 2.9 mg (42% reduction) in the column sediments, with 1.45 ± 0.06 mg eluting in the column effluents and 20.6 ± 3.0 mg being unaccountable, presumably due to biodegradation. Based on stoichiometry of denitrification, nitrate consumption and nitrite and nitrous oxide production were sufficient to account for the observed loss. In contrast, JP-4 levels only dropped from 2,070 ± 260 mg to 1,750 ± 22 mg (15% reduction). Despite the similar distribution of contaminants in the two columns of this first column pair, FETAX mortality remained unchanged at 93.3% in the first column and dropped from 93.3% to 11.7% in the second. Toxicity reduction could not be therefore directly attributed to either BTEXTMB or JP-4 levels. After 7 months, total mass reductions were 93.1 ± 1.1% and 35 ± 1.6% for BTEXTMB and JP-4, respectively, and FETAX mortality and malformation had declined to less than 10%. These data show that closure standards requiring complete removal of residual hydrocarbon may overestimate the time required to counteract sediment toxicity, and that nitrate-based bioremediation may be a viable treatment alternative for fuel-contaminated aquifers.
Ion-pair association of substituted phenolates with K+ in octanol
Authors: Strathmann Timothy J , Jafvert Chad T
Published: March 2010

The speciation, environmental distribution, and ultimate fate of phenolic compounds, a class of hydrophobic ionizable organic compounds, is influenced by both their hydrophobic and electrostatic characteristics. In this study, electrical conductance measurements were employed to characterize the ion-pair association properties of a monovalent inorganic cation (K+) with substituted phenolate anions in the model hydrophobic solvent, 1-octanol. Quantification of such processes is important for characterizing the overall partitioning to and speciation in octanol of phenolic compounds. Data were analyzed and association constants were calculated using a modified form of the Fuoss–Onsager equation for electrical conductivity. Results indicate that the magnitude of ion-pair association correlates with the electron-donating and -withdrawing characteristics of phenolic ring substituents. A quantitative structure–activity relationship was developed correlating ion-pair association constants to the sum of Hammett substituent constants for each species. The data suggest that for some phenolate salts, charged triple ion or higher aggregate formation may occur at elevated concentrations. A qualitative interpretation of this phenomenon and the selectivity of its occurrence are discussed.
Effects of application rate on avian risk from granular pesticides
Authors: Stafford Tamara R , Best Louis B
Published: March 2010

Fensulfothion was formulated on silica granules to evaluate the relationship between avian risk of adverse effects from granular pesticides and granule availability. Captive house sparrows (Passer domesticus) were offered the granular pesticide in bands on soil surfaces at application rates of 50, 100, 200, 400, 800, 1,200, 1,600, or 2,000 LD50/ft2. Individual pesticide granules were formulated with ½ the LD50 for house sparrows (0.3 mg/kg). Bird behavior, survival, and brain cholinesterase activity were used to assess pesticide exposure. A significant negative correlation between brain ChE activity and the natural logarithm of application rate indicated that the relationship between avian risk and granule availability was asymptotic rather than linear. Thus, the assumption, implicit in the LD50/ft2 risk index, that the potential exposure of birds to granular pesticides increases as granule availability increases may result in overestimates of risk to birds from granular pesticides, particularly at higher granule application rates.
Molecular orbital calculations to describe microbial reductive dechlorination of polychlorinated dioxins
Authors: Lynam Mary M , Kuty Michal , Damborsky Jiri , Koca Jaroslav , Adriaens Peter
Published: March 2010

Ab initio restricted Hartree Fock and density functional theory (DFT), as well as semiempirical Austin model 1 and parametrization method 3 molecular orbital calculations were carried out for a range of chlorinated dioxin molecules to obtain molecular descriptors such as HOMO–LUMO gaps (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) and partial atomic charges. The HOMO–LUMO gap is an indicator of stability in a molecule: the larger the gap the greater the stability of the molecule toward further reaction. These calculations indicate that with increasing extent of chlorination, the gap decreases. The observed charge pattern shows that carbon atoms in the peri (1,4,6,9) ring positions have a partial negative charge while those in the lateral (2,3,7,8) position have a partial positive or small partial negative charge. The descriptors, from the more precise DFT method, were used to rationalize experimental observations of dechlorination of dioxins. Reductive dechlorination pathways from two different experimental studies were examined using partial charges and estimated Gibbs free energy of dechlorination. In both experimental studies, highly thermodynamically favorable and less thermodynamically favorable pathways were observed. For a given chlorinated dioxin, when more than one degradation pathway was possible, dechlorination in the most thermodynamically favored pathway occurred at the most positively charged carbon atom in the ring, which was usually a lateral carbon atom. These results are discussed in light of a possible mechanism for reductive dechlorination.
Responses of two earthworm populations with different exposure histories to chlorophenol contamination
Authors: Haimi Jari , Paavola Sirkku
Published: March 2010

Two populations of the earthworm Aporrectodea tuberculata (Eisen), one from a chlorophenol contaminated and another from an uncontaminated site in central Finland, were exposed to acute, toxic, and sublethal concentrations of pentachlorophenol (PCP). Exposure history seemed to have only slight effect on the responses of the earthworms. Values of a lethal concentration of 50% in the humus-rich soil were very high, 1,870 μg PCP per gram for the earthworms from the contaminated site and 1,520 μg/g for the earthworms from the uncontaminated site. No differences in the accumulation of PCP from the soil into the earthworms between the two populations were found. Earthworms from both populations seemed to be able to avoid low concentrations of PCP. Earthworms from the contaminated site tended to produce more cocoons in PCP-spiked than in clean soil, whereas earthworms from the uncontaminated site produced more cocoons in clean soil. No other significant differences in the growth or reproduction between the populations were found. It seems that in humus-rich soils chlorophenols have not acted as an important selection pressure, probably because of their strong sorption to soil organic matter. However, the results showed that earthworms are able to reduce their exposure by avoidance behavior.
Impact of glufosinate-ammonium and bialaphos on the zooplankton community of a small eutrophic northern lake
Authors: Faber Marvin J , Thompson Dean G , Stephenson Gerald R , Kreutzweiser David P
Published: March 2010

The impact of glufosinate-ammonium and bialaphos on the zooplankton community in a small eutrophic lake was investigated using in situ enclosures. Concentrations inducing a 20% reduction in abundance (EC20), as interpolated from best-fit, nonlinear regression analyses were similar for both herbicides and ranged from 0.03 to 0.16 mg/L for various zooplankton taxa. Similarly, median effective concentrations (EC50) estimates ranged from 0.12 to 0.50 mg/L. Thus, toxicity endpoints overlapped and in some cases were well below expected environmental concentrations calculated for accidental direct overspray (1 mg/L) or drift events (0.25 mg/L). Significant concentration-dependent reductions were observed within the first 2 weeks following application and for a number of taxa persisted throughout the observation period (63 d posttreatment). At the highest treatment level, (10 mg/L), negative impacts were still apparent in the year following treatment. The results of this field study, which demonstrate significant negative effects on a variety of zooplankton taxa at environmentally relevant concentrations and relatively slow recovery therefrom, suggest a substantial risk of sustained adverse impacts on the zooplankton communities should these herbicides contaminate shallow lentic ecosystems. Extensive mitigative measures are required to protect such water bodies from potential impacts of phosphinothricin-based herbicides.
Combined effects of alachlor and atrazine on benthic algal communities in artificial streams
Authors: Carder Justin P , Hoagland Kyle D
Published: March 2010

A duplicated factorial approach was used to assess the combined effects of three environmentally realistic levels of alachlor (0.0, 5.0, and 90.0 μg/L), cross-classified with three environmentally realistic levels of atrazine (0.0, 12.0, and 150.0 μg/L), on indigenous epipelic algae (mud-dwelling species, characteristic of agricultural streams). The experiment was conducted in 18 recirculating laboratory streams over a 4-week period. Biovolume of viable algal cells and relative abundance of the six dominant algal species were utilized as experimental endpoints. Community biovolume was impacted throughout the experiment in streams treated with 12.0 and 150.0 μg/L atrazine and in streams containing 90.0 μg/L alachlor, but only in samples collected at 4 weeks. The effects of atrazine and alachlor together on algal community biovolume appeared to be additive rather than synergistic. The relative abundance of two dominant algal taxa were impacted in streams treated with alachlor, but only one species remained affected over time. The lack of significant interactions is most likely attributable to the different modes of action of atrazine and alachlor. The additive nature of these two herbicides should be an important consideration in the development of water quality criteria.
Effects of photoinduced toxicity of fluoranthene on amphibian embryos and larvae
Authors: Hatch Audrey C , Burton G Allen
Published: March 2010

Embryos and newly hatched larvae of three amphibian species, the spotted salamander (Ambystoma maculatum), the northern leopard frog (Rana pipiens), and the African clawed frog (Xenopus laevis), were exposed to fluoranthene and ultraviolet (UV) light in two scenarios. Embryos were exposed in a laboratory setting from an early developmental stage through hatching under artificial UV light, and newly hatched larvae were exposed outdoors in varying sunlight intensity levels. Outdoor exposures indicated greater sensitivity in the toxic response than did laboratory exposures. In the laboratory, mortality and malformation of X. laevis were the most sensitive indicators of exposure. Xenopus laevis was also the most sensitive species tested to the effects of UV light alone. Hatching success of R. pipiens was monitored outdoors and was not a useful predictive endpoint in the determination of photoinduced toxicity; however, newly hatched larvae were sensitive to the effects of photoinduced toxicity. Amybstoma maculatum and X. laevis larvae were affected by low (μg/L) concentrations of fluoranthene in sunlight. These findings suggest that low levels of polycyclic aromatic hydrocarbons could be acting synergistically with environmental factors such as UV light to place young amphibians at risk.
Sorption of cadmium to bacterial extracellular polymeric sediment coatings under estuarine conditions
Authors: Schlekat Christian E , Decho Alan W , Chandler G Thomas
Published: March 2010

Mcrobial extracellular polymeric substances (EPS) are ubiquitous features in aquatic environments. Produced by surface-adherent bacteria and microalgae, EPS are often present as coatings on surfaces of sediment particles and exhibit high affinities for divalent cationic metals. Thus, EPS sediment coatings may participate in the fate of potentially toxic metals. We coated particulate silica (8–10 μm) with EPS produced by NISC1, a bacterium isolated from estuarine sediments, in order to measure the metal binding characteristics of these coatings. We used the radioisotope 109Cd to measure effects of salinity (salinity = 2.5, 7.5, and 25‰), Cd concentration([Cd] = 0.038, 5, and 50 mg/L), and pH (pH = 5, 6, 7, 8, and 9) on Cd sorption to EPS-coated (EPS-silica) silica and to noncoated silica (NC-silica). Also, Cd sorption by NISC1 EPS coatings was compared to coatings of polymers formed by the bacterium Alteromonas atlantica and the alga Macrocystis porifera. Under all circumstances, EPS coatings increased the affinity of silica for Cd. Extracellular polymeric substance-particulate aggregates rapidly sorbed up to 90% of Cd from aqueous solution. Extracellular polymeric substance sediment coatings exhibited a maximum log distribution coefficient (Kd) of 6.5 at 2.5‰. Sorption of Cd to NC-silica was affected by salinity and metal concentration, whereas sorption of Cd to EPS-silica was only affected by salinity under high metal concentrations. Changes in pH had a dramatic effect on Cd sorption, with the proportion of free Cd to sorbed Cd changing from approximately 90% at pH 5 to 5% at pH 9. Desorption of Cd from EPS-silica was enhanced with increasing salinity. These experiments suggest that EPS coatings actively participate in binding dissolved overlying and pore-water metals in estuarine sediments.
Effect of aroclor 1248 concentration on the rate and extent of polychlorinated biphenyl dechlorination
Authors: Sokol Roger C , Bethoney Charlotte M , Rhee G-Yull
Published: March 2010

Dechlorination kinetics of polychlorinated biphenyls (PCBs) were investigated in Aroclor 1248-spiked sediments at 16 concentrations ranging from 0 to 200 ppm using sediment microorganisms from the Reynolds site in the St. Lawrence River, New York, USA, over a 58-week incubation period. The time course of dechlorination, measured as the total Cl per biphenyl, consisted of an initial lag phase followed by rapid dechlorination and then a plateau that represented an apparent endpoint of dechlorination. A clear threshold concentration was found between 35 and 45 ppm; there was no dechlorination observed at seven concentrations below this level. Above the threshold concentration, dechlorination rate was a function of sediment PCB concentration. The rate, calculated as the slope of the rapid phase, was linear within the concentration range investigated. The maximum extent of dechlorination also increased with initial Aroclor concentrations; only 4% of Cl per biphenyl was removed at 45 ppm, and the removal was saturated at approximately 36% above 125 ppm. This difference appeared to be due to whether or not dechlorination involved meta-rich congeners such as 25-2′ (IUPAC no. 18), 25-2′5′- (no. 52), and 23-2′5′ chlorobiphenyl (no. 44). These results indicate that a major controlling factor for natural remediation potential in sediments is the initial PCB concentration that determines the maximum extent of dechlorination rather than the dechlorination rate.
Comparison of methods for inorganic sulfur speciation in a petroleum production effluent
Authors: Witter Amy E , Jones A Daniel
Published: March 2010

Multiple analytical techniques were compared for identification and quantification of inorganic sulfur species present in a sulfidic waste effluent (produced water) generated during offshore oil production. Inorganic sulfur species including sulfide, polysulfides, thiosulfate, sulfite, and sulfate were measured in produced water samples using sampled direct current polarography, differential pulse polarography, iodometry, spectrophotometry after derivatization with Ellman's reagent, high-performance liquid chromatography after derivatization with 2,2′-dithiobis(5-nitropyridine), and barium chloride precipitation of sulfate. Sulfide was determined in seven produced water samples at concentrations of 1 to 8 mM (˜39% of measured inorganic sulfur), as well as sulfate (˜56%), polysulfides (˜3%), and thiosulfate (˜2%); sulfite was detected only occasionally in lower concentrations (≤50 μM). Comparison of four methods used for sulfide measurement demonstrated systematic differences in results generated by various methods. Measurements of inorganic sulfur species in produced water are influenced by coupled equilibria between different chemical forms. Polysulfides exert an important role in coupling reactions between sulfur in intermediate oxidation states, and their presence can affect quantitation of these species when physical separations or standard additions perturb solution equilibria.
Hexahydro-1,3,5-trinitro-1,3,5-triazine translocation in poplar trees
Authors: Thompson Phillip L , Ramer Liz A , Schnoor Jerald L
Published: March 2010

This article evaluates the translocation of the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in hybrid poplar trees (Populus deltoides × nigra, DN34) grown in hydroponic solutions. Mass balances with [U-14C]RDX were used to assess RDX translocation. Up to 60% of the RDX uptaken by the tree accumulated in leaf tissues. Analysis of plant extracts by high-performance liquid chromatography equipped with radiochemical detection indicated that RDX was not significantly transformed during exposure periods of up to 7 d. The bioaccumulation of RDX may be an important concern for phytoremediation efforts.
Effects of quantity, quality, and contact time of dissolved organic matter on bioconcentration of benzo[a]pyrene in the nematode Caenorhabditis elegans
Authors: Haitzer Markus , Burnison B Kent , Höss Sebastian , Traunspurger Walter , Steinberg Christian E W
Published: March 2010

Quantity and quality of dissolved organic matter (DOM) and the time allowed for DOM to interact with organic contaminants can influence their bioavailability. We studied the effect of natural aquatic DOM that had been in contact with benzo[a]pyrene (B[a]P) for 1 to 12 d on the bioconcentration of B[a]P in the nematode Caenorhabditis elegans. Dissolved organic matter quality and quantity was varied by using DOM from three different sources, each in three different concentrations. A model, based on the assumption that only freely dissolved B[a]P is bioavailable, was employed to estimate “biologically determined” partition coefficients [Kp(biol.)]. Expressing the data for each combination of DOM source and contact time in a single Kp (biol.) value allowed a direct comparison of the effects of different DOM qualities and contact times. Our results show that the effect of DOM from a specific source was dependent on DOM quantity, but we also observed a distinct effect of DOM quality (represented by different sampling locations) on the bioconcentration of B[a]P. Contact time had no significant influence for the effects of two DOM sources on the bioconcentration of B[a]P. However, the third DOM source was significantly more effective with increased contact time, leading to lower B[a]P bioconcentration in the nematodes.
Ecological risk assessment in a large river-reservoir: 3. Benthic invertebrates
Authors: Jones Daniel S , Barnthouse Lawrence W , Suter Glenn W , Efroymson Rebecca A , Field Jennifer M , Beauchamp John J
Published: March 2010

The sediments of Poplar Creek and the Clinch River are contaminated with a wide variety of chemicals, including heavy metals, polycyclic aromatic hydrocarbons, and PCBs. Sources include the U.S. Department of Energy's Oak Ridge Reservation as well as both known and unidentified upstream activities. We investigated the risks to benthic invertebrates posed by chemicals in these sediments as part of a comprehensive ecological risk assessment performed to support Superfund clean-up decisions. Poplar Creek was the only river reach for which significant risks were determined. This conclusion was based on several lines of reasoning: sediment-associated organisms at most sites were exposed to levels of several contaminants that have been observed to be toxic; the biosurvey results show a greater than 20% reduction relative to reference sites in taxa richness and abundance; the statistical analysis of the physical, contaminant, and biosurvey data did not exclude contaminants as possible causal factors; and the sediment toxicity tests were too ambiguous to definitively exclude impacts in this reach. This assessment demonstrates the importance of collecting biological data, including sediment toxicity tests and biological surveys; statistically analyzing the relationships of chemicals, physical variables, and measured effects (e.g., toxicity or benthic invertebrate densities); and using sediment chemical and effects distributions in addition to point estimates of exposure and screening benchmarks.
The effects of nitrite on behavior and metamorphosis in cascades frogs (Rana cascadae)
Authors: Marco Adolfo , Blaustein Andrew R
Published: March 2010

Amphibian metamorphosis is a period of drastic morphologic reorganization, during which larvae experience a decrease in locomotor ability and are more vulnerable to predation. Our results indicate that exposure to sublethal concentrations of nitrite in the water induces behavioral and morphologic changes in the Cascades frog (Rana cascadae). Tadpoles exposed to a nitrite concentration of N-NO2- at 3.5 mg/L transformed more slowly than control tadpoles exposed to dechlorinated tap water. No difference 2 was found in time at emergence and snout—vent length at emergence between experimental and control tadpoles, but development was retarded in tadpoles exposed to nitrite and they emerged at an earlier developmental stage. Also, tadpoles exposed to nitrite occupied shallow water more frequently than did control tadpoles.
Effect of gut clearance on metal body concentrations in Hyalella azteca
Authors: Neumann Paul T.M , Borgmann Uwe , Norwood Warren
Published: March 2010

Gut content can contribute significantly to the metal body burdens in sediment-exposed Hyalella azteca even if it has no direct effect on toxicity. To determine the duration and the effect of gut clearance on total body concentrations, we exposed H. azteca for 1 week to a spiked sediment (lead, cadmium, zinc, and copper); a second set of amphipods was kept in cages above the sediment. Following transfer into clean water (25°C) for 96 h, lead and zinc concentrations showed a biphasic decline, with a stronger decrease in the first 4 to 6 h, when gut clearance contributed significantly to metal loss. After 6 h, metal loss was apparently due to excretion from the body. Without gut clearance, the “real” body concentrations of lead and zinc in sediment-exposed amphipods were overestimated by 438 and 44%, respectively. Gut clearance did not have a visible effect on cadmium and copper body burdens because the body and sediment concentrations were similar. After a depuration time of 6 h, direct excretion from the body resulted in a drop of less than 10% in the total body burdens of lead, cadmium, zinc, and copper compared to the gutcorrected time-zero body burdens. After 24 h, this loss increased up to 27%. Feeding during the depuration period did not have a significant influence on gut clearance. A model that allows estimation of the influence of gut content on the total body concentration of undepurated invertebrates from the bioconcentration factor is evaluated.
Comparative studies of the reduction behavior of chromium(VI) by humic substances and their precursors
Authors: Nakayasu Ken , Fukushima Masami , Sasaki Keiko , Tanaka Shunitz , Nakamura Hiroshi
Published: March 2010

Hexavalent chromium (Cr[VI]) is reduced by dissolved organic carbons (DOCs) such as humic substances, tannic acid (TA), and gallic acid (GA). The kinetic constants and the resulting chemical species after the reduction were compared with each other. The kinetic constants for GA and TA, which are model precursors of humic substances, were two to three orders of magnitude larger than those for the humic substances when these kinetic constants were expressed as a function of the molar concentration of the reductive functional group (Fred) in various DOCs. After the reduction of Cr(VI), the percentages of the species complexed with GA and TA were higher than those with the humic substances. This appears to be due to the formation of high molecular weight compounds by polymerization during the reduction of Cr(VI) and complexation of Cr(III) with the polymerized compounds. The UV-vis spectrophotometric data and gel permeation chromatography support this view.
Mussels as sentinels of organotin pollution: Bioaccumulation and effects on P450-mediated aromatase activity
Authors: Morcillo Yolanda , Albalat Amaya , Porte Cinta
Published: March 2010

Organotin pollution has been monitored in mollusks from the Catalan coast (Spain). Tributyltin (TBT) was the major compound detected, ranging from 200 to 1,100 ng/g wet weight as Sn. Tributyltin metabolites and triphenyltin (TPhT) were also detected, although to a lesser extent. Virtually organotin-free mollusks were obtained in the Alfacs Bay (Ebro Delta). Aromatase activity was determined in the digestive gland of a selected number of samples by measuring the tritiated water release from [1β-3H]-androstenedione. Enzyme activity was linear as a function of incubation time and protein content of the microsomal fraction. It was determined at a substrate concentration of 10 μM, and it exhibited a typical Michaelis–Menten kinetic, with an apparent constant, Km, of 32 ± 3 μM. Low aromatase activity (217–264 fmol/h/mg protein) was seen in mussels sampled in TBT-polluted environments compared with mussels from the virtually organotin-free point (345 fmol/h/mg protein). These results support the hypothesis of a TBT-mediated inhibition of cytochrome P450-aromatase activity in mussels, although no significant changes on tissue titers of testosterone/estradiol were observed.
Classification of explosives transformation products in plant tissue
Authors: Larson Steven L , Jones Robert P , Escalon Lynn , Parker Don
Published: March 2010

Explosives contamination in surface or groundwater used for the irrigation of food crops and phytoremediation of explosives-contaminated soil or water using plant-assisted biodegradation have brought about concerns as to the fate of explosives in plants. Liquid scintillation counting, high-performance liquid chromatography, and gel permeation chromatography were utilized to characterize explosives (hexahydro-1,3,5-trinitro-1,3,5-triazine and trinitrotoluene) and their metabolites in plant tissues obtained from three separate studies. Analyzing tissues of yellow nutsedge (Cyperus esculentus), corn (Zea mays), lettuce (Lacuta sativa), tomato (Lyopersicum esculentum), radish (Raphanus sativus), and parrot feather (Myriophyllum aquaticum) from three studies where exposure to explosives at nontoxic levels (1–2 mg/L in water) occurred showed that extensive transformation of the explosive contaminant occurred, variations were noted in uptake and transformation between terrestrial and aquatic plants, the products had significantly higher polarity and water solubility than the parent compounds, and the molecular sizes of the transformation products were significantly greater than those of the parent compounds (approximately 300 times greater).
Causes of toxicity in stormwater runoff from sawmills
Authors: Bailey Howard C , Elphick James R , Potter Alan , Chao Eric , Konasewich Dennis , Zak J Brian
Published: March 2010

Samples of stormwater runoff from nine sawmills in British Columbia, Canada, were tested for acute toxicity with juvenile rainbow trout over a 23-month period. Forty-two of the 58 samples tested exhibited toxicity. Causes of toxicity were investigated using toxicity identification evaluation techniques. Toxicity was attributed to divalent cations, particularly zinc, in 32 of the samples. The low hardness associated with most of the samples increased the potential for metal toxicity. For example, the LC50 of zinc was 14 μg/L at a hardness of 5 mg/L. Toxicity in the remaining samples was largely attributed to tannins and lignins and was associated with areas of bulk log handling. No evidence was found to indicate that antisapstain chemicals applied to freshly cut wood contributed to toxicity.
Bioaccumulation profiles of polychlorinated biphenyl congeners and organochlorine pesticides in Ganges river dolphins
Authors: Senthilkumar Kurunthachalam , Kannan Kurunthachalam , Sinha Ravindra K , Tanabe Shinsuke , Giesy John P
Published: March 2010

Isomer-specific concentrations of polychlorinated biphenyls (PCBs) including non-, mono-, and di-ortho-substituted congeners, DDT and its metabolites, hexachlorocyclohexane (HCH) isomers, chlordane compounds, and hexachlorobenzene (HCB) were determined in river dolphin blubber and prey fishes collected during 1993 through 1996 from the River Ganges in India. Concentrations of organochlorines were also measured in the milk and liver of dolphins, benthic invertebrates, and sediments. The DDTs and PCBs were the predominant compounds found in dolphin tissues and fish that comprise the diet of dolphins. Concentrations of DDTs and PCBs in the blubber of dolphins were in the range of 30 to 120 and 1.5 to 25 μg/g, lipid weight, respectively. Pentaand hexachlorobiphenyls collectively accounted for 68 to 80% of the total PCB concentrations in river dolphins. Hexachlorobiphenyl congener 138 (2,2′,3,4,4′,5′-) was the most abundant in dolphin blubber and prey fishes. The isomer/congener pattern of PCBs and organochlorine pesticides suggested that there is less metabolism due to cytochrome P450 enzymes in Ganges river dolphins than in marine or terrestrial mammals. The mean 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) estimated in river dolphin blubber was greater than those that can cause adverse effects in mink. Comparison of organochlorine concentrations in river dolphins with those of the values reported for samples analyzed during 1988 through 1992 suggested that the contamination by these compounds has increased in the River Ganges.
Impact of grain scale heterogeneity on slow sorption kinetics
Authors: Kleineidam Sybille , Rügner Hermann , Grathwohl Peter
Published: March 2010

Groundwater contamination by dissolved organic compounds frequently occurs in valley aquifers that consist of highly heterogeneous sand and gravel sediments. Remediation and risk assessment (e.g. reactive transport modeling) requires detailed information on the sorption/desorption kinetics in such aquifer materials. In this paper we present data on slow sorption kinetics of phenanthrene and the composition of several aquifer materials that are typical for southern Germany and Switzerland. The heterogeneity of the aquifer material is described in terms of the physical and chemical properties (e.g., grain size, organic carbon content, intraparticle porosity, sorption parameters, and rate constants for intraparticle diffusion) of the sediment constituents (lithocomponents). Phenanthrene sorptive uptake in a heterogeneous bulk sample can be predicted using a numerical model only if the composition and geochemical heterogeneity (different sorptivities and porosities of the lithocomponents) are considered. It could be shown that even within a narrow grain size fraction, the geochemical heterogeneity has to be incorporated for the prediction of long-term sorptive uptake or release of organic contaminants.
Tissue carboxylesterase activity of rainbow trout
Authors: Barron Mace G , Charron Kem A , Stott William T , Duvall Stephanie E
Published: March 2010

The activity of carboxylesterase (CaE), a class of nonspecific serine hydrolases, was evaluated in vitro in tissues and microsomes of rainbow trout and compared to esterase activity in rats, other fish species, and embryo to adult life stages of trout. Trout gill and liver microsomes exhibited substantial CaE activity and limited variation over the range of 2 to 40°C, with a temperature optimum of approximately 22°C. Trout sera and rat liver microsomes exhibited a temperature optimum of approximately 35 to 40°C. The CaE of trout liver (maximum reaction rate [Vmax] = 672 nmol/min/mg microsomal protein) was four times less than in rats. Apparent Michaelis constant (Km) values ranged from 28 (trout liver) to 214 (trout sera) μM. Values of Vmax/Km suggested that in vivo CaE activity of trout liver would be about three times higher than serum, 135 times higher than gill, and three times lower than rat liver. The CaE activity in whole rainbow trout homogenates significantly increased 300% per gram of tissue to 1,200% per milligram of protein between the yolk-sac and juvenile stages. The CaE activity of whole fish homogenates was not significantly different in juvenile rainbow trout, channel catfish, fathead minnows, and bluegill. The results demonstrate that rainbow trout had high esterase activity over a broad range of temperatures, that CaE activity significantly increased between the yolk-sac and juvenile life stages, and that variation between the CaE activity in trout and three other families of freshwater fish was limited. The CaE activity in fish is expected to substantially influence the accumulation and toxicity of pesticides and other esters entering the aquatic environment.
Toxicity of aryl- and benzylhalides to Daphnia magna and classification of their mode of action based on quantitative structure–activity relationship
Authors: Marchini Silvia , Passerini Laura , Hoglund Marilynn D , Pino Anna , Nendza Monika
Published: March 2010

The acute toxicity of aryl- and benzylhalides to Daphnia magna was investigated to test the validity of existing classification schemes for chemicals by mode of action, mainly based on fish studies, and the applicability of predictive quantitative structure–activity relationship (QSAR) models. Halobenzenes and halotoluenes are generally agreed to be unambiguous baseline toxicants (class I) with the major exception of the benzylic structures, which are reactive in fish tests (class III). Eighty-nine percent of the arylhalides tested in this study match a log Pow-dependent QSAR, including fluorinated, chlorinated, brominated, and iodinated derivatives, thereby confirming the validity of the baseline models also for variously halogenated compounds (other than only-chloro compounds). The toxicities of the benzylhalides relative to baseline QSARs clearly indicate that these compounds belong to two classes by mode of action, i.e., they either act as narcotic toxicants (class I) or reveal excess toxicity due to unspecific reactivity (class III). On some occasions, the assignment to the two classes in D. magna deviates from the structural rules derived from fish, i.e., iodinated compounds as well as α,α-Cl2-toluenes lack reactive excess toxicity but behave as nonpolar nonspecific toxicants. The QSARs derived during this study reveal lower slopes and higher intercepts than typical baseline models and, together with the analysis of mixture toxicity studies, behavioral studies, and critical body burden, advocate the hypothesis that there are several different ways to produce baseline toxicity. Most halobenzenes and halotoluenes are actually baseline chemicals with some extra reactivity and as such form a subgroup, whose limits still have to be defined. Different primary sites of action could explain why the chemicals are discriminated by different classification systems, but still they must have some rate-limiting interaction in common (e.g., lipid diffusion) as they fit the same log Pow-dependent baseline QSAR.
Major ion toxicity in effluents: A review with permitting recommendations
Authors: Goodfellow William L , Ausley Lawrence W , Burton Dennis T , Denton Debra L , Dorn Philip B , Grothe Donald R , Heber Margarete A , Norberg-King Teresa J , Rodgers John H
Published: March 2010

Effluent toxicity testing methods have been well defined, but for the most part, these methods do not attempt to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role of various total dissolved solids in effluents on regulatory compliance has emerged during the last few years and has caused confusion in technical assessment and in permitting and compliance issues. This paper assesses the issue of ionic strength and ion imbalance, provides a brief summary of applicable data, presents several case studies demonstrating successful tools to address toxicity resulting from salinity and ion imbalance, and provides recommendations for regulatory and compliance options to manage discharges with salinity/ion imbalance issues. Effluent toxicity resulting from inorganic ion imbalance and the ion concentration of the effluent is pervasive in permitted discharge from many industrial process and municipal discharges where process streams are concentrated, adjusted, or modified. This paper discusses procedures that use weight-of-evidence approaches to identify ion imbalance toxicity, including direct measurement, predictive toxicity models for freshwater, exchange resins, mock effluents, and ion imbalance toxicity with tolerant/susceptible text species. Cost-effective waste treatment control options for a facility whose effluent is toxic because of total dissolved solids (TDS) or because of specific ion(s) are scarce at best. Depending on the discharge situation, TDS toxicity may not be viewed with the same level of concern as other, more traditional, toxicants. These discharge situations often do not require the conservative safety factors required by other toxicants. Selection of the alternative regulatory solutions discussed in this paper may be beneficial, especially because they do not require potentially expensive or high-energy–using treatment options that may be ineffective control options. The information presented is intended to provide a better understanding of the role of ion imbalance in aquatic toxicity testing and to provide various recommendations that should be considered in addressing these issues.
Toxicity of glyphosate and triclopyr using the frog embryo teratogenesis assay—Xenopus
Authors: Perkins Peggy J , Boermans Herman J , Stephenson Gerald R
Published: March 2010

The effects of glyphosate ([N-phosphonomethyl]glycine) and triclopyr ([[3,5,6-trichloro-2-pyridinyl]oxy]acetic acid) on the embryonic development of Xenopus laevis were evaluated using Frog Embryo Teratogenesis Assay—Xenopus (FETAX). Rodeo®, the isopropylamine (ipa) salt of glyphosate formulated without a surfactant was found to be the least toxic, with a LC5 and LC50 of 3,779 and 5,407 mg acid equivalent (AE)/L, respectively. The LC5 and LC50 of Roundup®, the ipa salt of glyphosate formulated with a surfactant, was 6.4 and 9.4 mg AE/L, respectively. The surfactant component of Roundup, polyoxyethyleneamine (POEA), had a LC5 and LC50 of 2.2 and 2.7 mg/L, respectively. Garlon® 3A, the triethylamine salt of triclopyr, had a LC5 and LC50 of 119 and 162.5 mg AE/L, respectively. The LC5 and LC50 of Garlon 4®, the butoxyethyl ester of triclopyr, was 6.7 and 9.3 mg AE/L, respectively. Considering a theoretical worst case scenario when the highest rates recommended for glyphosate (12 L of Roundup/ha) or triclopyr (8 L of Garlon/ha) are applied to water 15 cm in depth, the expected environmental concentrations calculated on the basis of AE would be 2.8 and 2.6 mg AE/L, respectively. The margins of safety (LC5/expected environmental concentrations) for frog embryos exposed to these concentrations would be approximately 2, 2, 47, and 1,312 for Roundup, Garlon 4, Garlon 3A, and Rodeo, respectively.
Metal body burden and biological sensors as ecological indicators
Authors: Birge Wesley J. , Price David J , Shaw Joseph R , Spromberg Julann A , Wigginton Andrew J , Hogstrand Christer
Published: March 2010

Metal body burden (BB) was analyzed in three groups of organisms evaluated as sentinel monitors of metal exposure. The study site was a lotic system of moderate gradient that received effluent outfalls from an uranium enrichment plant. Metal BBs (e.g., Ag, Cd, Cr, Cu) increased in the order Cheumatopsyche spp. (caddisfly), Campostoma anomalum (central stoneroller minnow), and Stenonema spp. (mayfly). This was consistent with their classifications as metal-tolerant, moderately tolerant, and sensitive taxa, respectively. The Ag, Cd, and Cu BBs in stoneroller minnows from upstream, effluent-receiving, and downstream stations correlated strongly with macroinvertebrate bioassessment (BA) scores (r ≤ —0.95), numbers of taxa (r = —0.95), and the Ephemeroptera, Plecoptera, Trichoptera indices (r = —0.82 to —0.94). Proportional differences in metal BBs in the minnow were used to derive metal multipliers that were applied to total recoverable metal concentrations to calculate bioavailable metal. The bioavailable metal fractions correlated with BA scores and numbers of taxa (e.g., Ag, r ≤ —0.97; Cu, r = —0.95). When five metals (i.e., Ag, Cd, Cu, Cr, Pb) were included in an additive model, results also correlated with BA scores (r = —0.93) and numbers of taxa (r = —0.86). Metal BB in minnows was a strong indicator of ecological impact and provided a means of determining bioavailable metals. Also, we describe the development of the metal biosensor, which incorporates a reconstructed fish gill epithelium, the primary target of metal exposure. This in vitro biosensor should directly quantify bioreactive metals that cross the epithelium and react with a genetically engineered intracellular detector. This biosensor complements biotic ligand models based on surface binding of metals to gill epithelia.
A comparison of metal-induced lethality and behavioral responses in the nematode Caenorhabditis elegans
Authors: Dhawan Ritu , Dusenbery David B , Williams Phillip L
Published: March 2010

Behavioral changes are believed to be a sensitive indicator of toxicant exposure but can be very difficult to quantify. Using the free-living soil nematode Caenorhabditis elegans, a computer tracking system was used that measures several behavioral parameters for approximately 100 subjects on a real-time basis. Toxicant exposures can be performed in soil, on agar plates, or in aquatic media. Following the exposure period, the worms are transferred to a thin-layered agar slab for viewing in dark-field illumination by a video camera interfaced directly to a computer. Information can be obtained on a number of behavioral parameters including number of subjects moving, their individual rates of locomotion, and the frequency of change in direction. Exposure to five metals (Pb, Cu, Cd, Al, and Zn) were tested in this study to evaluate behavioral changes in the worm. The nematodes were exposed for 24 h to concentrations of an individual metal in aquatic medium representing the interstitial pore water within the soil. Under identical conditions, concurrent LC50 and BC50 (concentration at which movement is reduced by 50% compared with controls) values were determined for each metal tested. The results from computer tracking revealed significant changes in rate of locomotion at concentrations of less than 10% of the respective LC50 value.
Gender benders at the beach: Endocrine disruption in marine and estuarine organisms
Authors: Oberdörster Eva , Cheek Ann Oliver
Published: March 2010

Several consensus definitions of the term endocrine disruptor have appeared recently, but all definitions include the important, though frequently implicit, stipulation that the animal is not distressed or in obvious discomfort. Instead, a superficially healthy animal is experiencing alterations in hormone synthesis, transport, receptor interaction, metabolism, excretion, or feedback regulation. In addition, hormone disruption may occur during sex differentiation, and its effects may not be manifested until after sexual maturation. Many cases of chemically induced reproductive impairment have been reported for both freshwater and marine species. However, reproductive impairment may not necessarily result from hormone disruption and should be considered suggestive, but not conclusive, evidence of endocrine disruption. A suite of in vivo and in vitro assays will more adequately assess whether a compound is truly endocrine disrupting. This review will cover basic endocrinology of marine and estuarine invertebrates and vertebrates, methods for detecting endocrine disruption, and examples of endocrine disruption in various species.