bluuebunny/crossref_metadata_2025_split huggingface dataset:
Responses of two earthworm populations with different exposure histories to chlorophenol contamination
Authors: Haimi Jari , Paavola Sirkku 
Published: March 2010

Abstract
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

Abstract
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

Abstract
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

Abstract
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

AbstractMcrobial 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

AbstractDechlorination 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.