bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of a mine tailings spill on feeding and metal concentrations in yellow perch (Perca flavescens)
Authors: Draves James F , Fox Michael G 
Published: March 2010

AbstractIn this study, we examined the effects of a gold mine tailings spill in the Montreal River (northern Ontario, Canada) on juvenile yellow perch (Perca flavescens), a benthic-feeding fish, and identified the major contributors to their uptake of tailings metals (Pb, Zn, Cd, and Cu) in dietary items and river water. Juvenile perch sampled from a 6-km reach of the river where most of the tailings were deposited had significantly less food in their stomachs than individuals sampled from a reference reach of the river. Concentrations of Pb in invertebrate prey taxa from the contaminated reach were 9 to 20 times higher than in those sampled from the reference reach. These differences were consistent with a higher concentration of Pb in perch from the contaminated reach. In contrast, Zn concentrations were high in river water and perch from both the reference and contaminated reaches, and little diffence was found in Zn concentration between invertebrate prey types sampled from the two reaches. No significant differences were found in Cu or Cd concentrations in yellow perch sampled from the two reaches. Higher levels of Pb in the major prey types from the contaminated reach indicate that dietary uptake may be the major vector for Pb accumulation in yellow perch from the Montreal River.
Applications of efficiency measurements in bioaccumulation studies: Definitions, clarifications, and a critique of methods
Authors: Penry Deborah L 
Published: March 2010

Abstract
Measurements of digestion, absorption, and assimilation efficiencies play central roles in physiological and ecological studies of nutrition and in toxicological studies of bioaccumulation. There is, however, a pervasive problem with inconsistency in the definition and use of efficiency terms and in their measurement and interpretation. Digestion, absorption, and assimilation efficiencies are frequently confused, and the term “assimilation efficiency” is commonly and incorrectly used as a synonym for digestion and absorption efficiencies. To differentiate measurements that are truly assimilation efficiencies from measurements that are digestion efficiencies and absorption efficiencies, explicit definitions of terms and examination of methodologies are necessary. In general, comparisons of ingested food and feces are digestion efficiencies and comparisons of ingested food and tissues are assimilation efficiencies. Absorption efficiencies can be determined from comparisons of ingested food and feces when the food component of interest is directly absorbed without digestion (e.g., some particle-associated toxicants) or is an absorbable tracer (e.g., 14C) that is not altered by digestion. Absorption efficiencies of toxicants are commonly measured using two tracer-based methods, the dual tracer method and the selectivity index (SI) method. The assumptions of the dual tracer method can at least be tested and validated while the assumptions of the SI method are not valid. The SI method requires the assumption of a value for total organic carbon (TOC) absorption efficiency in order to calculate a toxicant absorption efficiency, and analysis of the equations associated with the SI method shows that calculating a toxicant absorption efficiency using an assumed TOC absorption efficiency is not any more justifiable than just assuming a toxicant absorption efficiency.
Evidence for long-range transport of a low to medium molecular-weight petroleum product off Central California, USA
Authors: Phillips Charles , Clayton John , Evans John , Hom Wilson 
Published: March 2010

Abstract
Suspended particles collected within southern Santa Maria Basin (CA, USA) during November 1991 contained unusually elevated concentrations of parent and alkylated polycyclic aromatic hydrocarbons (PAHs) and patterns in straight chain alkanes and saturated biomarkers (terpanes and steranes) indicative of contamination by a distilled petroleum product from a California-sourced oil. Because no active offshore oil and gas drilling was occurring at the time, and there was no record of diesel spills or evidence from previous samplings of discharges of diesel fuel-contaminated drilling muds, petroleum hydrocarbons in the suspended sediments likely were related to a source other than platform discharges. The timing as well as the hydrocarbon composition suggested the presence of a petroleum product (diluent) that was released from an oil field at Guadalupe, approximately 50 km north of Santa Maria Basin. To evaluate diluent contributions, the hydrocarbon composition of suspended sediments was characterized and compared to those of possible source materials, including diluent, formation oils, and well cuttings, using principal component analysis (PCA). Suites of saturated and aromatic hydrocarbons, enriched in the C13 to C23 range, contained in some suspended sediments were consistent with relative abundances of low to medium molecular weight components in diluent but were different from those in formation and seep oils. Results of the PCA support the compositional similarities between the diluent and affected suspended sediments. This suggests that a petroleum product was transported as an oil-particle mixture over long distances with relatively minimal degradation. Wide dispersion of diluent increased potential exposures of marine organisms to toxic lower molecular weight PAHs.
Kinetics of tetrachloroethylene-reductive dechlorination catalyzed by vitamin B12
Authors: Burris David R , Delcomyn Carrie A , Deng Baolin , Buck Leslie E , Hatfield Kirk 
Published: March 2010

Abstract
Reductive dechlorination kinetics of tetrachloroethylene (PCE) to ethylene catalyzed by vitamin B12 using Ti[III] citrate as the bulk reductant was examined in a vapor/water batch system. A kinetic model incorporating substrate–B12 electron-transfer complex formation and subsequent product release was developed. The model also accounted for the primary reductive dechlorination pathways (hydrogenolysis and reductive β elimination) and vapor/water-phase partitioning. Reaction rate constants were sequentially determined by fitting the model to experimental kinetic data while moving upward through consecutive reaction pathways. The release of product from the complex was found to be second order with respect to substrate concentration for both PCE and acetylene; all other substrates appeared to release by first order. Reductive β elimination was found to be a significant reaction pathway for trichloroethylene (TCE), and chloroacetylene was observed as a reactive intermediate. Acetylene production appears to be primarily due to the reduction of chloroacetylene derived from TCE. The reduction of cis-dichloroethylene (cis-DCE), the primary DCE isomer formed, was extremely slow, leading to a significant buildup of cis-DCE. The kinetics of acetylene and vinyl chloride reduction appeared to be limited by the formation of relatively stable substrate–B12 complexes. The relatively simple model examined appears to adequately represent the main features of the experimental data.
Aquatic biodegradation behavior of pentachlorophenol assessed through a battery of shake flask die-away tests
Authors: Ingerslev Flemming , Baun Anders , Nyholm Niels 
Published: March 2010

Abstract
The aerobic aquatic biodegradability of pentachlorophenol (PCP) was studied in standard Organization for Economic Cooperation and Development/International Organization for Standardization shake flask screening tests for ready biodegradability and in more environmentally realistic surface water die-away tests with low chemical concentrations. Screening tests were conducted with either activated sludge or supernatant from settled activated sludge. Concentrations of activated sludge were 30 and 0.3 mg suspended solids per liter. Sludges were either freshly collected or initially preexposed to PCP. With supernatant, only low inoculum levels were used (0.5 ml/L). Some surface water tests were carried out with sediment amendment. Added chemical concentrations ranged from 1 to 74,000 μg/L. At nontoxic concentrations, PCP was rapidly biodegradable after an adaptation period of about 10 to 20 d. At concentrations below about 10 μg/L, degradation rates decreased, and the shape of the degradation curves indicated a shift from growth-linked degradation to non-growth-linked degradation. Addition of sediment to surface water reduced the acclimation periods but did not influence the subsequent degradation rate. Preexposure of activated sludge to PCP drastically eliminated the acclimation period and increased the tolerance of the sludge to PCP toxicity. With PCP used as a model compound, the results show that a battery of simple shake flask tests is suitable for provision of a detailed characterization of the biodegradability chemical compounds.
Bioaccumulation of polycyclic aromatic hydrocarbons by earthworms: Assessment of equilibrium partitioning theory in in situ studies and water experiments
Authors: Ma Wei-chun , van Kleunen André , Immerzeel Jaap , de Maagd P Gert-Jan 
Published: March 2010

Abstract
The purpose of this study was to assess the suitability of applying equilibrium partitioning (EqP) theory to predict the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) by earthworms when these are exposed to contaminated soils in the field. Studies carried out in situ in various contaminated floodplain sites showed the presence of linear relationships with intercept zero between the lipid-normalized concentration of different PAHs in the earthworm Lumbricus rubellus and the organic-matter-normalized concentration of the compounds in soil. The demonstration of such an isometric relationship is in agreement with the prediction of EqP theory that the biota-soil accumulation factor (BSAF) should be independent of the octanol/water partition coefficient, log Kow. The average BSAF of PAH compounds in the sampled 20-cm top layer of soil was 0.10 (range, 0.03–0.26). The present study also investigated the route of uptake of PAHs for earthworms in soil. The bioconcentration factor of low-molecular-weight PAHs, such as phenanthrene, fluoranthene, and pyrene, was derived from bioconcentration kinetic modeling of water-only experiments and found to be of the same order of magnitude as the bioaccumulation factor in the field when the latter was normalized to calculated concentrations in soil pore water. The results indicated that the exposure of earthworms to PAHs in soil is mediated through direct contact of the worms with the dissolved interstitial soil-water phase, further supporting the applicability of EqP theory to PAHs. Our experimental data on the biotransformation of PAHs suggest that earthworms possess some capacity of metabolization, although this does not seem to be a major factor in the total elimination of these compounds. Even though the EqP approach was found to be applicable to low-molecular-weight PAHs with respect to the prediction of bioaccumulation by earthworms in the field, the results were less conclusive for high-molecular-weight compounds, such as benzo[a]pyrene.
Use of semipermeable membrane devices for studying effects of organic pollutants: Comparison of pesticide uptake by semipermeable membrane devices and mussels
Authors: Sabaliünas Darius , Lazutka Juozas , Sabaliüniene Inesa , Södergren Anders 
Published: March 2010

Abstract
Uptake of four pesticides—the organochlorines chlordane and endosulfan and the synthetic pyrethroids fenvalerate and allethrin—by triolein-containing semipermeable membrane devices (SPMD) and by the lake mussel Anodonta piscinalis was studied in a laboratory continuous-flow system. Uptake of the analytes by the SPMDs and mussels was linear during the exposure period of 20 d. These kinetic data were used to calculate the first-order uptake rate constants. On a SPMD-whole body basis, the uptake rates were 3.5 to 5.5 times higher in the membrane devices than in the organisms. The synthetic pyrethroids were sampled at lower rates than the organochlorines, and this difference may be attributed to the larger molecular dimensions of the pyrethroids rather than analyte molecular weight and lipophilicity, which were similar for all test compounds. Because of the disparate sampling rates, concentration factors of analytes differed between SPMDs and mussels. However, the percent composition (ratios) of analytes in SPMDs and in mussels was similar, which indicates that SPMDs may serve as good surrogates for aquatic organisms with respect to the discriminatory uptake of hydrophobic chemicals. Semipermeable membrane device dialysate, mussel extract, as well as two artificial mixtures of the four pesticides were tested with standard toxicity and genotoxicity tests, including Microtox® (inhibition of bacterial luminescence), Daphtoxkit™, and Rotoxkit™ (toxicity tests with freshwater invertebrates Daphnia pulex and Brachionus calyciflorus, respectively), and sister chromatid exchange in human lymphocytes in in vitro assay. Results of these tests suggest that integration of the SPMD technique and bioassays may be a valuable approach for the assessment of levels and effects of bioavailable hydrophobic pollutants.
Promutagen activation by the green algaSelenastrum capricornutum
Authors: Sauser Kathleen R , Chung King-Thom , Wong Tit-Yee 
Published: March 2010

AbstractThe capability of Selenastrum capricornutum to activate o-phenylenediamine (OPD) and 2-aminofluorene (2-AF) was tested in a modified Ames assay in which the activation component (S9) was replaced by the algal cells. Normal-grown algae did not activate OPD but these cells activated 2-AF by sixfold. Copper induces a peroxidase in S. capricornutum. Algae pregrown on copper-enriched medium increased the mutagenicity of OPD by more than 16-fold, but these cells failed to further activate 2-AF. However, 2-AF was further activated by algae pretreated with flavone, Aroclor, 5,6-naphthoflavone, or 2,4-dichlorophenoxyacetic acid, but not lindane or ethanol. This suggested that a cytochrome P450 system was involved in 2-AF activation. Coincubating algae with cytochrome P450 inhibitors including diethyldithiocarbamate, methimizole, or acetaminophen, but not catechin, 7–8-naphthoflavone, or CuCl2 reduced the activation level of 2-AF significantly.
Effects of tributyltin on a coastal North Sea plankton community in enclosures
Authors: Jak Robbert G , Ceulemans Michiel , Scholten Martin C Th , van Straalen Nico M 
Published: March 2010

Abstract
The toxicity of tributyltin (TBT) to a neritic North Sea plankton community was studied in experiments using outdoor enclosures with a volume of 1.2 m3. Nominal TBT concentrations of 0, 0.056, 0.1, 0.18, 0.32, and 0.56 μg/L were tested in duplicate for 28 d. A first-order decrease of TBT in the water column was observed for the highest nominal concentration, with a rate constant of 0.12 per day (t½ of 5.7 d). Median effective concentration (EC50) values were determined for the dominant zooplankton species, Temora longicornis (Copepoda). The EC50 values were lower when calculated for biomass than when calculated for density and ranged between 0.15 and 0.32 μg/L, depending on exposure time. At high TBT concentrations, enhanced pH levels and oxygen concentrations were observed, indicating high algal production levels, which would result from reduced grazing by zooplankton. Depending on exposure time, EC50 values for the indirect effect of TBT on pH varied between 0.10 and 0.22 μg/L, indicating that the indirect effects of TBT are at least as sensitive as the direct effects. The study showed that testing chemicals in outdoor enclosures can provide data complementary to that obtained from laboratory toxicity tests.
Toxic cell concentrations of three polychlorinated biphenyl congeners in the green alga Selenastrum capricornutum
Authors: Mayer Philipp , Halling-Sørensen Bent , Sijm Dick T H M , Nyholm Niels 
Published: March 2010

Abstract
Algal growth inhibition tests were performed with the unicellular green alga Selenastrum capricornutum and three 14C-labeled polychlorinated biphenyl (PCB) congeners. Toxicity was related to external aqueous concentrations and additionally to internal algal bound PCB concentrations. Estimates of the concentrations at 50% effectiveness (EC50s) for the three PCB congeners ranged within a factor of 17 (14–241 nmol/L) when based on measured aqueous concentrations. When based on internal toxicant concentrations (toxic cell concentrations, TCC50) the corresponding range was 6.7 to 14.3 mmol/kg wet weight. Thus, changing the basis from external to internal concentrations reduced the range by almost one order of magnitude. Additional toxic cell concentrations of five monoaromatic compounds and S. capricornutum were calculated from literature data to be in the same order of magnitude as the experimental toxic cell concentrations for the PCBs, whereas EC50 values for all substances ranged by more than four orders of magnitude. The experimental and calculated data indicate that observed differences in the estimated EC50 values were mainly due to differences in bioconcentration behavior rather than to different intrinsic toxicities. These findings are in agreement with the concept of baseline toxicity, meaning that a number of hydrophobic organics exerts their acute toxicity by one relatively nonspecific mode of action.
Chronic toxicity of pulse-dosed fenoxycarb toDaphnia magnaexposed to environmentally realistic concentrations
Authors: Hosmer Alan J , Warren Laurie W , Ward Timothy J 
Published: March 2010

AbstractEffects of fenoxycarb on growth and reproduction of Daphnia magna were examined under realistic exposure conditions as defined by predictions from laboratory fate studies and observations in the field. Initial concentrations were administered in a single pulse dose and altered to mimic the reduction of fenoxycarb that occurs following field application to natural waters (half-life ⋍ 10 hours). Potential effects on the developmental stage of test organisms were determined by exposure of four age groups: less than 24 h, 4 to 6 d, 8 d, and 11d. There were no significant effects on survival or time to first brood of first- and second-generation daphnids in any age group. The number of young per daphnid was significantly lower than controls only among daphnids that were less than 24 h old at test initiation and exposed to the highest initial measured concentration of fenoxycarb (45 μg/L). The estimated maximum acceptable toxicant concentration (MATC) was 26 μg/L, calculated from exposure of the most sensitive age group (less than 24 h old) to environmentally realistic levels of fenoxycarb. This represents a substantial reduction in toxicity when compared to the MATC of 0.0016 μg/L previously reported from a standard, constant-exposure study.
Desulfonation of biotransformation products from commercial linear alkylbenzenesulfonates
Authors: Mampel Jörg , Hitzler Tanja , Ritter Axel , Cook Alasdair M 
Published: March 2010

Abstract
Earlier work shows that the biodegradation and biotransformation of commercial linear alkylbenzenesulfonate (LAS) as a carbon source for growth leads to a residue of sulfonated aromatic compounds, termed refractory organic carbon, from the synthetic by-products. We now show that this refractory organic carbon, after separation from sulfate ion, is utilized extensively as a sulfur source for bacterial growth. The products of desulfonation are expected to be biodegradable, so we question the value of adjectives like refractory.
Atrazine effects on estuarine macrophytes Spartina alterniflora and Juncus roemerianus
Authors: Lytle Julia S , Lytle Thomas F 
Published: March 2010

Abstract
Two dominant estuarine marsh plants, Juncus roemerianus and Spartina alterniflora, were exposed for 35 d to three dose levels of atrazine with measured concentrations of approximately 0.03, 0.25, and 3 mg/L to assess peroxidase (POD) activity, lipid peroxidation, chlorophyll changes, and growth rates. The objective of the study was to evaluate toxicity of atrazine and to measure multiple endpoints to assess their value as biomarkers of atrazine stress or resistance. In S. alterniflora, exposure to 3.1 mg/L of atrazine did not significantly inhibit growth, generated no lipid peroxidation products, and did not affect chlorophyll production, but did significantly enhance POD activity. In contrast, in J. roemerianus, atrazine exposure significantly inhibited growth at 3.8 mg/L, produced lipid peroxidation products and inhibited chlorophyll production in a dose-response fashion, and did not elicit a POD response. In combination, POD activity and lipid peroxidation are useful indicators of atrazine stress to these plants. Results of the study indicate that J. roemerianus would decline or die off if exposed to chronically high environmental concentrations of atrazine, whereas minimal damage would occur to S. alterniflora.
Unexpectedly high mercury level in pelleted commercial fish feed
Authors: Choi Monica Heekyoung , Cech Joseph J 
Published: March 2010

Abstract
An unexpectedly high mercury (Hg) level was found in a pelleted commercial fish feed used to feed fish in laboratory and fish farm settings. Mean total Hg (T-Hg) concentration in the commercial fish pellets was 66 ppb (ranging from 35 to 90 ppb). Mean total selenium (T-Se) concentration in the pellets was 1,120 ppb (ranging from 790 to 1,360 ppb). Total Hg and Se in the whole blood of Sacramento blackfish and in the fish feed were determined by inductively coupled plasma-mass spectrometry (ICP-MS). During a 10-week sampling period T-Hg in blood fluctuated between 35 and 56 ppb. A highly significant, positive correlation (r = 0.99, p &lt; 0.01) was found between T-Hg in the fish blood and in the fish feed through the sampling period. On the other hand, no correlation was found between T-Se in the fish feed and T-Hg or T-Se blood level. Researchers working with fish in Hg studies need to know that fish pellets may contain Hg and to consider the influence of these pellets in their results.
Genetics of radionuclide-contaminated mosquitofish populations and homology between Gambusia affinis and G. holbrooki
Authors: Theodorakis Christopher W , Bickham John W , Elbl Tricia , Shugart Lee R , Chesser Ronald K 
Published: March 2010

Abstract
The effects of radionuclide contamination on genetic structure of eastern mosquitofish (Gambusia holbrooki) populations from the U.S. Department of Energy's Savannah River Site (SRS) were investigated to develop methods of assessing ecological risk of chronic exposures to xenobiotics. Fish from two contaminated and two reference sites were examined by the randomly amplified polymorphic DNA (RAPD) technique, which revealed that the frequency of three markers was greater in the contaminated than the reference sites and that the frequency of two markers was greater in the reference than in the contaminated sites. A previous study examined populations of western mosquitofish (G. affinis) from the Oak Ridge National Laboratory (ORNL) and found that certain RAPD markers were present in radionuclide-contaminated ORNL populations at a higher frequency than in reference populations. The “contaminant-indicative” markers observed in the SRS populations were the same size and amplified by the same polymerase chain reaction primers used in the ORNL study. Southern blot analysis revealed that the SRS G. holbrooki contaminant-indicative markers were homologous to the ORNL G. affinis contaminant-indicative markers. The observation that two species show similar patterns of band frequency shifts at two separate localities is consistent with the hypothesis that these DNA markers may originate from genetic elements that provide a selective advantage in contaminated habitats. Thus, the methodology used in these studies may prove to be useful to indicate population-level effects of environmental contamination.