bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reductive dechlorination of polychlorinated biphenyls in sediment from the Twelve Mile Creek arm of Lake Hartwell, South Carolina, USA
Authors: Pakdeesusuk Usarat , Freedman David L. , Lee Cindy M. , Coates John T. 
Published: March 2010

Abstract
Lake Hartwell is a U.S. Army Corps of Engineers reservoir system located on the state line between South Carolina and Georgia, USA. The lake was contaminated with an estimated 200 metric tons of polychlorinated biphenyls ([PCBs]; mainly Aroclor 1016 and 1254), and the entire Twelve Mile Creek watershed and the Seneca River arm of Lake Hartwell were placed on the National Priorities List. Monitored natural attenuation was chosen as a remedy for the contaminated sediment. The relatively warm temperature of Lake Hartwell and lack of significant cocontaminants along with the PCBs distinguish this site from others that have been studied for microbially mediated reductive dechlorination. Microcosm studies were conducted with sediment from two locations in the Twelve Mile Creek arm and confirmed the presence of indigenous microorganisms capable of reductively dechlorinating Aroclor 1254, which contains predominantly tetra-, penta-, and hexachlorobiphenyl. The average number of total chlorines per biphenyl decreased from 4.8 to 4.9 to 2.9 to 3.0, following 250 to 260 d of incubation. The maximum observed dechlorination rates were 0.29 to 0.87 μg-atoms Cl− per gram sediment dry weight per week. The onset of dechlorination activity correlated strongly with maximum methanogenesis, which occurred without a lag in samples from the site that showed signs of in situ fermentation activity. Dechlorination occurred primarily at the meta and para positions (58–63% removal), with no apparent decrease in ortho chlorines. This most closely resembles pattern M, characterized by preferential removal of unflanked and flanked meta chlorines. The microcosm results are consistent with sediment cores analyzed from the same locations, which indicate accumulation with depth of the same ortho- and para-substituted congeners. It therefore appears that the success of monitored natural attenuation for Lake Hartwell will hinge on covering the recalcitrant PCBs with a sufficient amount of uncontaminated sediment to isolate them from the food chain.
Biodegradation of plasticizers by Rhodotorula rubra
Authors: Gartshore James , Cooper David G. , Nicell Jim A. 
Published: March 2010

Abstract
The degradation of plasticizers by the yeast Rhodotorula rubra J-96-1 (American Type Culture Collection 9449) in the presence of glucose was studied. The plasticizers included the commonly used bis-2-ethylhexyl adipate (B(EH)A), dioctyl phthalate (DOP), and dioctyl terephthalate (DOTP), and the less commonly used dipropylene glycol dibenzoate (D(PG)DB) and diethylene glycol dibenzoate (D(EG)DB). The proposal had been made that the latter two plasticizers be used as alternatives to the first three, which have been associated with negative environmental impacts. The degradation of D(PG)DB or D(EG)DB led to a significant increase in solution toxicity, which was associated with the production of metabolites resulting from the incomplete breakdown of the plasticizers. The toxic metabolites in the D(PG)DB system were identified as isomers of dipropylene glycol monobenzoate. A pathway for the formation of this metabolite was proposed. The metabolite observed when D(EG)DB was being degraded was tentatively identified as diethylene glycol monobenzoate by analogy to the D(PG)DB system. In contrast, no metabolites were observable and toxicity did not increase in the media during the degradation of B(EH)A, DOP, or DOTP by R. rubra. Collectively, these results do not support the use of D(PG)DB and D(EG)DB as environmentally safe alternatives to B(EH)A, DOP, or DOTP.
Assessing the long-range transport potential of polybrominated diphenyl ethers: A comparison of four multimedia models
Authors: Wania Frank , Dugani Chandrasagar B. 
Published: March 2010

Abstract
Data from a comprehensive literature search of environmentally relevant physical-chemical properties for nine poly-brominated diphenyl ethers (PBDE), ranging from a monobrominated congener to the fully brominated decabromodiphenyl ether, were evaluated and adjusted to achieve both internal and interhomologue consistency. These data were then used in four model-based long-range transport potential (LRTP) assessment methods. The models TaPL3-2.10, ELPOS-1.1.1, Chemrange-2, and Globo-POP-1.1 were found to yield comparable predictions. A comparison of the LRTP estimates for the PBDEs with those of benchmark chemicals (polychlorinated biphenyls [PCBs]) suggest that the lower-brominated congeners have a LRTP comparable to that of PCBs known to be subject to significant LRT, whereas the highly brominated congeners have a very low potential to reach remote areas. This is in agreement with field measurements in remote regions that indicate that the lighter components of commercially produced PBDE mixtures predominate. Deviations between Chemrange and the models based on the concept of a characteristic travel distance were due to differences in the assumed height of the air compartment, which influences the relative importance of atmospheric degradation and deposition processes. The three models assuming a uniform temperature of 25°C may underestimate the LRTP of the smaller congeners. Only atmospheric parameters had a notable influence on the LRTP estimates by TaPL3, ELPOS, and Chemrange, whereas the relative enrichment of chemicals in the Arctic calculated by Globo-POP is additionally sensitive to the parameters related to the interaction of temperature with air—surface exchange and degradation in surface compartments.
Effect of dissolved organic matter of various origins and biodegradabilities on the bioaccumulation of polycyclic aromatic hydrocarbons inDaphnia magna
Authors: Gourlay Catherine , Tusseau-Vuillemin Marie-Hélène , Garric Jeanne , Mouchel Jean-Marie 
Published: March 2010

AbstractAs a preliminary study of the influence of urban organic matter on the bioavailability of polycyclic aromatic hydrocarbons (PAHs), the effect of different types of dissolved organic matter (DOM) on the bioaccumulation of fluoranthene, pyrene, or benzo[a]pyrene in Daphnia magna was studied. Commercial humic substances, DOM from the aeration basin of a wastewater treatment plant, and highly biodegradable DOM (algae or animal extracts) were tested. The bioaccumulation of benzo[a]pyrene was reduced by each DOM (up to 80% reduction with humic substances). Pyrene bioaccumulation was also decreased by each DOM to a lesser extent. Fluoranthene bioaccumulation was affected by the presence of humic acids only. In each experiment, the solution containing humic DOM led to the lowest bioaccumulation. Supposing that only dissolved PAHs were bioavailable, the reduction of bioaccumulation allowed a biological estimate of the partition coefficients of DOM and PAH, KDOC. The estimated coefficients were positively related to the aromaticity of DOM and negatively related to its biodegradability.
Demography of short-tailed shrew populations living on polychlorinated biphenyl—contaminated sites
Authors: Boonstra Rudy , Bowman Lanna 
Published: March 2010

Abstract
In ecological risk assessment, a key necessity is to understand how contaminants known to have negative impact on laboratory mammals affect the population demography of mammals living in their natural environment. We examined the demography of six local populations of the short-tailed shrew (Blarina brevicauda) living in eastern deciduous forest palustrine habitat along the Housatonic River (MA, USA) on soils contaminated with a range of polychlorinated biphenyl (PCB) concentrations (1.5–38.3 ppm). The objective of the study was to assess whether PCBs adversely affect the population demography of these small mammals living in their natural environment. Blarina were selected for study because they would be expected to readily bioaccumulate PCBs from the soil. Populations were intensively live trapped on 1-ha grids from spring to autumn 2001. There was no relationship between any demographic parameter and PCB soil concentrations. Densities were high (usually exceeding 20/ha, and on two grids exceeded 60/ha in summer); survival was good (typically 60–75% per 30 d); and sex ratio, reproduction rates, growth rates, and body mass were within the ranges reported in the literature. Thus, these shrew populations showed no detectable impact on their population demography from living on PCB-contaminated sites.
Complexity in multimedia mass balance models: When are simple models adequate and when are more complex models necessary?
Authors: Cahill Thomas M. , Mackay Donald 
Published: March 2010

Abstract
Three environmental multimedia models of varying degrees of complexity are compared to assess when simple models are adequate and when more complex models are advantageous. The simplest model, the level II (L-II) model, assumes all environmental media are at chemical equilibrium, whereas the more complex models treat chemical disequilibrium between well-mixed media (standard level IV [L-IV] model) or the major media are subdivided into separate layers to simulate heterogeneity (high-resolution level IV [HR-IV] model). The three models are compared for their performance in predicting steady-state, regional concentrations; dynamic, local-scale concentrations; and chemical persistence in the environment. The results indicate that the L-IV model often provides adequate regional simulations when chemical emission occurs to air or water. This model also is useful for assessing chemical persistence in both steady-state and dynamic scenarios. More complex models, such as the HR-IV model, are suggested for local-scale, dynamic simulations or when the chemical emission occurs to soil because they better characterize rates of intramedia transport, which can greatly affect the model predictions. The simplest L-II model predicts environmental concentrations that can differ significantly from those of more complex models, but it is useful for establishing partitioning tendencies and for ranking chemicals for their relative persistence in steady-state situations.
Degradation and formation of polycyclic aromatic compounds during bioslurry treatment of an aged gasworks soil
Authors: Lundstedt Staffan , Haglund Peter , Öberg Lars 
Published: March 2010

Abstract
The goals of this study were to investigate the relative degradation rates of polycyclic aromatic compounds (PACs) in contaminated soil, and to assess whether persistent oxidation products are formed during their degradation. Samples were taken on five occasions during a pilot-scale bioslurry treatment of soil from a former gasworks site. More than 100 PACs were identified in the soil, including unsubstituted polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkyl-PAHs), heterocyclic PACs, and oxygenated PAHs (oxy-PAHs), such as ketones, quinones, and coumarins. During the treatment, the low molecular weight PAHs and heterocyclics were degraded faster than the high molecular weight compounds. The unsubstituted PAHs also appear to have degraded more quickly than the corresponding alkyl-PAHs and nitrogen-containing heterocyclics. No new oxidation products that were not present in the untreated soil were identified after the soil treatment. However, oxy-PAHs that were present in the untreated soil were generally degraded more slowly than the parent compounds, suggesting that they were formed during the treatment or that they are more persistent. Two oxidation products, 1-acenaphthenone and 4-oxapyrene-5-one, were found at significantly higher concentrations at the end of the study. Because oxy-PAHs can be acutely toxic, mutagenic, or carcinogenic, we suggest that this group of compounds should also be monitored during the treatment of PAH-contaminated soil.
Variations in α-Hexachlorocyclohexane enantiomer ratios in relation to microbial activity in a temperate estuary
Authors: Padma Tiruponithura V. , Dickhut Rebecca M. , Ducklow Hugh 
Published: March 2010

Abstract
Changes in the enantiomer ratios (ERs) of chiral pollutants in the environment are often considered evidence of biological alteration despite the lack of data on causal or mechanistic relationships between microbial parameters and ER values. Enantiomer ratios that deviate from 1:1 in the environment provide evidence for the preferential microbial degradation of one enantiomer, whereas ER values equal to 1 provide no evidence for microbial degradation and may mistakenly be interpreted as evidence that biodegradation is not important. In an attempt to link biological and geochemical information related to enantioselective processes, we measured the ERs of the chiral pesticide α-hexachlorocyclohexane (α-HCH) and bacterial activity (normalized to abundance) in surface waters of the York River (VA, USA) bimonthly throughout one year. Despite lower overall α-HCH concentrations, α-HCH ER values were unexpectedly close to 1:1 in the freshwater region of the estuary with the highest bacterial activity. In contrast, ER values were nonracemic (ER ≠ 1) and α-HCH concentrations were significantly higher in the higher salinity region of the estuary, where bacterial activity was lower. Examination of these data may indicate that racemic environmental ER values are not necessarily reflective of a lack of biodegradation or recent input into the environment, and that nonenantioselective biodegradation may be important in certain areas.
Quantifying copper and cadmium impacts on intrinsic rate of population increase in the terrestrial oligochaete Lumbricus rubellus
Authors: Spurgeon David J. , Svendsen Claus , Weeks Jason M. , Hankard Peter K. , Stubberud Hege E. , Kammenga Jan E. 
Published: March 2010

Abstract
Demographic methods can translate toxicant effects on individuals into consequences for populations. To date few such studies have been conducted with longer-lived invertebrates. This is because full life-cycle experiments are difficult with such species. Here we report the effects of copper and cadmium on the key demographic parameter intrinsic rate of population increase (r) in a long-lived invertebrate (an earthworm). The approach used to derive r was based on robust measurement of effects on life-cycle traits in three specifically designed toxicity tests and integration of this data within a demographic model. The three laboratory tests used to generate values for specific life-cycle parameters under copper and cadmium exposure were suited to the task. Significant effects on a range of separate adult and juvenile life-cycle parameters were seen. Integration of parameter values within the demographic equation indicated that for copper, r was reduced only at a concentration that also caused adult mortality. For cadmium, a more graded exposure-dependent effect on fitness was seen, with r reduced at sublethal concentrations. The concentration response patterns for r found for the two metals suggest significantly different consequences for earthworm populations exposed to sublethal levels of copper and cadmium.
Lead accumulation in feathers of nestling black-crowned night herons (Nycticorax nycticorax) experimentally treated in the field
Authors: Golden Nancy H. , Rattner Barnett A. , Cohen Jonathan B. , Hoffman David J. , Russek-Cohen Estelle , Ottinger Mary Ann 
Published: March 2010

Abstract
Although lead can attain high concentrations in feathers, interpretation of the biological significance of this phenomenon is difficult. As part of an effort to develop and validate noninvasive methods to monitor contaminant exposure in free-ranging birds, lead uptake by feathers of nestling black-crowned night herons (Nycticorax nycticorax) was evaluated in a controlled exposure study. Four- to 6-d-old heron nestlings (one/nest) at Chincoteague Bay, Virginia (USA), received a single intraperitoneal injection of dosing vehicle (control, n = 7) or a dose of lead nitrate in water (0.01, 0.05, or 0.25 mg Pb/g body wt of nestling; n = 6 or 7/dose) chosen to yield feather lead concentrations found at low- to moderately polluted sites. Nestlings were euthanized at 15 d of age. Lead accumulation in feathers was associated with concentrations in bone, kidney, and liver (r = 0.32–0.74, p &lt; 0.02) but exhibited only modest dose dependence. Blood delta-aminolevulinic acid dehydratase activity was inhibited by lead, although effects on other biochemical endpoints were marginal. Tarsus growth rate was inversely related to feather lead concentration. Culmen growth rate was depressed in nestlings treated with the highest dose of lead but not correlated with feather lead concentration. These findings provide evidence that feathers of nestling herons are a sensitive indicator of lead exposure and have potential application for the extrapolation of lead concentrations in other tissues and the estimation of environmental lead exposure in birds.
The effects of ultraviolet-b radiation on the toxicity of fire-fighting chemicals
Authors: Calfee Robin D. , Little Edward E. 
Published: March 2010

AbstractThe interactive effects of ultraviolet (UV) and fire-retardant chemicals were evaluated by exposing rainbow trout (Oncorhyncus mykiss) juveniles and tadpoles of southern leopard frogs (Rana sphenocephala) to six fire-retardant formulations with and without sodium ferrocyanide (yellow prussiate of soda [YPS]) and to YPS alone under three simulated UV light treatments. Yellow prussiate of soda is used as a corrosion inhibitor in some of the fire-retardant chemical formulations. The underwater UV intensities measured were about 2 to 10% of surface irradiance measured in various aquatic habitats and were within tolerance limits for the species tested. Mortality of trout and tadpoles exposed to Fire-Trolr̀ GTS-R, Fire-Trol 300-F, Fire-Trol LCA-R, and Fire-Trol LCA-F was significantly increased in the presence of UV radiation when YPS was present in the formulation. The boreal toad (Bufo boreas), listed as endangered by the state of Colorado (USA), and southern leopard frog were similar in their sensitivity to these chemicals. Photoenhancement of fire-retardant chemicals can occur in a range of aquatic habitats and may be of concern even when optical clarity of water is low; however, other habitat characteristics can also reduce fire retardant toxicity.
Metallothionein concentrations in natural populations of gudgeon (Gobio gobio): Relationship with metal concentrations in tissues and environment
Authors: Van Campenhout Karen , Bervoets Lieven , Blust Ronny 
Published: March 2010

Abstract
A field monitoring campaign investigating the suitability of (Cd, Zn)-metallothionein concentrations (MTs) in different tissues of the gudgeon as a biomarker for metal contamination in the aquatic environment was conducted. Gudgeons were captured at 10 sampling sites on a river system in Flanders (Belgium). Nine sampling sites were situated along a Cd and Zn gradient with a nearby tributary as the reference site. Cadmium, Cu, and Zn concentrations were measured in the water and sediments. Concentrations of (Cd, Zn)-MT were measured in different organs (gill, liver, kidney) of gudgeon (Gobio gobio). The hepatic and gill Cd and Zn concentrations, as well as the hepatic (Cd, Zn)-MT concentrations, reflected the polymetallic contamination gradient. Moreover, the hepatic Cd and Zn concentrations could describe 72% of the variance in the (Cd, Zn)-MT concentrations in the liver, illustrating the possible use of hepatic MT concentrations as a biomarker for environmental metal contamination. In this way a dose-response relationship could be established under natural conditions. However, a poor negative relation between the Cd and Zn concentrations in the gills and the corresponding (Cd, Zn)-MT concentrations was found. No relation between the Cd and Zn concentrations in the kidney tissue and the corresponding (Cd, Zn)-MT concentrations could be established. These results clearly illustrate the tissue-specificity of the MT concentrations, thus for monitoring purposes MT concentrations should be measured in liver tissues, rather than in kidney or gill tissues.
Use of receiver operating characteristic curves to evaluate sediment quality guidelines for metals
Authors: Shine James P. , Trapp Crista J. , Coull Brent A. 
Published: March 2010

AbstractReceiver operating characteristic (ROC) curves are commonly used in the biomedical field to assess the quality of a diagnostic test. The area under an ROC curve, which ranges from 0.5 to 1.0, is a measure of the overall effectiveness of a diagnostic test. These curves can be used to elucidate compromises in sensitivity (ability to correctly classify a toxic sample as toxic) and specificity (ability to correctly classify a nontoxic sample as nontoxic) associated with a given threshold. In this study, ROC curves were used to evaluate methods for estimating acute toxicity of metals in marine sediments. Differences in the effectiveness of speciation (comparisons of labile sulfides with simultaneously extracted metals) and total sediment concentration (such as the National Oceanographic and Atmospheric Administration Guidelines, Washington, DC) approaches were assessed by using a database of field and laboratory spiked sediments. Despite uncertainties associated with these methods, the areas under the ROC curves ranged from 0.84 to 0.89 for all approaches tested, with no significant differences between speciation and whole sediment approaches. Thresholds commonly used by environmental managers, although yielding high sensitivity, came at the expense of low specificity. Thresholds providing desirable trade-offs in sensitivity and specificity generally are higher than commonly used thresholds.
Sequential bio- and phototransformation of the herbicide methabenzthiazuron in water
Authors: Malouki Moulay Abderrahmane , Giry Géraldine , Besse Pascale , Combourieu Bruno , Sancelme Martine , Bonnemoy Frédérique , Richard Claire , Delort Anne-Marie 
Published: March 2010

Abstract
We investigated the transformation of methabenzthiazuron in water by microorganisms and solar light. This compound was very slowly phototransformed when irradiated at λ &gt; 290 nm, but it could be successfully oxidized into 6-hydroxymethabenzthiazuron by Aspergillus niger, as shown by nuclear magnetic resonance experiments. The toxicity of this metabolite, as determined by the standardized Microtox® test, was sixfold lower than that of the parent molecule. The 6-hydroxymethabenzthiazuron was not further metabolized by A. niger but was photooxidized with ring cleavage of the aromatic ring and photodimerized on irradiation at λ &gt; 290 nm. In the presence of humic substances, the photodegradation was slower. We demonstrate that the transformations of methabenzthiazuron, observed either with the fungus A. niger or by the action of solar light, do not proceed via the urea chain N-dealkylation, as usually reported, but only via hydroxylation or cleavage of the benzene ring. This work shows the complementarity of both approaches, photo- and biodegradation, to study the fate of herbicides in the environment.