bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological risk assessment of pesticides on muskrats (Ondatra zibethicus) Inhabiting an agriculture area in Illinois, USA
Authors: Juhlin Steven E , Halbrook Richard S
Published: March 2010

A retrospective risk assessment was used to investigate whether pesticide use adversely affected populations of muskrats (Ondatra zibethicus), semi-aquatic mammals inhabiting agriculture drainage ditches in northwestern Illinois. Assessment endpoint benchmark concentrations in water were calculated for muskrats from laboratory rat multiple-generation reproduction no-observed-effect levels. The pesticide root zone model and exposure analysis modeling system simulated pesticide fate and revealed expected environmental concentrations (EECs) of pesticide in receiving water. The EECs following agriculture practices and meteorologic events typical of northern Illinois were below endpoint benchmark concentrations. A modeled worst-case scenario of exposure (three times the typical application rates and 1 cm of rain on the day of application) also revealed EECs below endpoint benchmarks. Assessment results suggested that muskrat populations in northern Illinois were not at risk from the application of pesticides. Results from two other lines of evidence further supported conclusions of this risk assessment.
Effects of mercury and selenium on glutathione metabolism and oxidative stress in mallard ducks
Authors: Hoffman David J , Heinz Gary H
Published: March 2010

Earlier studies have reported on the toxicity and related oxidative stress of different forms of Se, including seleno- D,L-methionine, in mallards (Anas platyrhynchos). This study compares the effects of Se (seleno-D,L-methionine) and Hg (methylmercury chloride) separately and in combination. Mallard drakes received one of the following diets: untreated feed (controls), or feed containing 10 ppm Se, 10 ppm Hg, or 10 ppm Se in combination with 10 ppm Hg. After 10 weeks, blood, liver, and brain samples were collected for biochemical assays. The following clinical and biochemical alterations occurred in response to Hg exposure: hematocrit and hemoglobin concentrations decreased; activities of the enzymes glutathione (GSH) peroxidase (plasma and liver), glutathione-S-transferase (liver), and glucose-6-phosphate dehydrogenase (G-6-PDH) (liver and brain) decreased; hepatic oxidized glutathione (GSSG) concentration increased relative to reduced glutathione (GSH); and lipid peroxidation in the brain was detected by increased thiobarbituric reactive substances (TBARS). Effects of Se alone included increased hepatic GSSG reductase activity and brain TBARS concentration. Selenium in combination with Hg partially or totally alleviated effects of Hg on GSH peroxidase, G-6-PDH, and GSSG. These findings are compared in relation to field observations for diving ducks and other aquatic birds. It is concluded that since both Hg and excess Se can affect thiol status, measurement of associated enzymes in conjunction with thiol status may be a useful bioindicator to discriminate between Hg and Se effects. The ability of Se to restore the activities of G-6-PDH, GSH peroxidase, and glutathione status involved in antioxidative defense mechanisms may be crucial to biological protection from the toxic effects of methylmercury.
An epizootic of common loons in coastal waters of North Carolina: Concentrations of elemental contaminants and results of necropsies
Authors: Augspurger Tom , Franson J C , Converse Kathryn A , Spitzer Paul R , Miller Erica A
Published: March 2010

A 1993 die-off of common loons (Gavia immer) in the coastal waters of North Carolina was investigated with emphasis on comparing mercury, selenium, arsenic, and lead between birds from the epizootic and reference specimens. Die-off specimens were emaciated but contained no ingested foreign bodies and no lesions suggestive of infectious disease. Results of bacteriology, virology, parasitology, and botulism testing were unremarkable. The geometric mean concentrations (wet weight) of liver mercury (10.9 ppm), and arsenic (0.96 ppm) did not differ between specimens from the die-off and reference loons from the same area that died of other causes. The geometric mean liver selenium concentration of die-off specimens (10.4 ppm) was significantly higher than that of reference loons. Liver lead concentrations were < 0.20 ppm in all but one sample (5.83 ppm). The geometric mean mercury concentration in the primary remiges of die-off specimens (5.44 ppm dry weight) was significantly lower than in reference birds. Liver mercury significantly correlated with liver selenium on a molar concentration basis. We interpret the range of liver mercury concentrations in birds from the epizootic, similar liver mercury concentrations in reference loons, and higher mercury concentrations in reference loon feathers as evidence that factors other than mercury were primarily responsible for the emaciation diagnosed as the cause of mortality.
Genotoxic substances in the St. Lawrence system I: Industrial genotoxins sorbed to particulate matter in the St. Lawrence, St. Maurice, and Saguenay rivers, Canada
Authors: White Paul A , Rasmussen Joseph B , Blaise Christian
Published: March 2010

Previous investigations of organic genotoxins in industrial effluents discharged into the St. Lawrence Rivers system (Quebec, Canada) indicated that a substantial fraction of the genotoxicity is adsorbed to suspended particulate matter. This study used the SOS Chromotest to investigate the presence, potency, and behavior of particle-bound genotoxins in the downstream ecosystem. The results indicate that although extracts of both suspended and sedimented particulate matter are genotoxic, suspended particulate matter samples are more potent in the absence of S9 activation, with the reverse being true for bottom sediments. The results confirmed a positive relationship between the genotoxicity of bottom sediment extracts and sediment organic matter content. A similar relationship between organic matter content and total polycyclic aromatic hydrocarbon (PAH) concentration indicates that putative genotoxins have physicochemical properties similar to the PAH class of contaminants. Conversion of PAH values to benzo[a]pyrene equivalents indicates that measured PAHs only account for a small fraction (∼10%) of the observed SOS Chromotest response. Sites that receive discharges from foundries, aluminum refineries, and petroleum refineries yielded several of the most genotoxic samples. Further analyses revealed that the genotoxicity of suspended and sedimented particulate matter extracts is empirically related to the genotoxicity of industrial discharges. Comparisons of total genotoxicity levels in suspended particulates and bottom sediments suggest that direct-acting substances adsorbed to suspended matter are rapidly degraded and/or converted to more stable progenotoxins upon deposition. Further research is required to test this hypothesis and investigate effects on indigenous biota.
A model of the fate of polycyclic aromatic hydrocarbons in the Saguenay Fjord, Canada
Authors: Lun Rebecca , Lee Kenneth , De Marco Lisa , Nalewajko Czesia , Mackay Donald
Published: March 2010

A comprehensive mass balance model is described that simulates the fate of polycyclic aromatic hydrocarbons (PAHs) in the Saguenay Fjord in eastern Quebec, Canada. The receiving environment is segmented into five compartments that are connected by upstream and downstream flows. Each segment consists of a layer of surficial sediment and a water column exposed to the atmosphere. The steady state model provides a method by which defined loadings of PAHs from the atmosphere and industrial sources are combined with other input parameters such as advective flow and atmospheric deposition rates to deduce quantities, concentrations, and transport and transformation rates. Results are presented for naphthalene, phenanthrene, and benzo[a]pyrene. The overall environmental pathways and simulation results are discussed. The simulated concentrations of benzo[a]pyrene in the sediment ranged from 100 to 315 ng/g, which are in good agreement with reported measurements.
Sediment toxicity and benthic communities in mildly contaminated mudflats
Authors: Nipper Marion G , Roper David S , Williams Erica K , Martin Michael L , Van Dam Laurence F , Mills Geoffrey N
Published: March 2010

Sediment physicochemical characteristics, benthic community structure, and toxicity were measured at reference and contaminated intertidal mudflats around the North Island of New Zealand. Chronic whole-sediment toxicity tests were conducted with the estuarine amphipod Chaetocorophium lucasi and the marine bivalve Macomona liliana, and pore-water toxicity tests were conducted with embryos of the echinoid Fellaster zelandiae. Although concentrations of organic chemicals and heavy metals were up to several orders of magnitude higher at the sites considered to be contaminated, levels of contamination were relatively low compared to internationally based sediment quality guidelines. Although no pronounced difference was found in benthic community structure between reference and contaminated sites, multivariate analysis indicated that natural sediment characteristics (total organic carbon, acid-volatile sulfide, ammonium) and factors related to contamination (dichlorodiphenyltrichloroethane, sediment toxicity) may have been affecting community structure. Although benthic effects caused by present levels of contamination are not yet dramatic, subtle changes in community structure related to pollution may be occurring. The two whole-sediment and the pore-water toxicity tests presented different response patterns. Growth of C. lucasi and M. liliana was a less sensitive endpoint than survival. None of the three toxicity tests responded more strongly to the contaminated than to the reference sites, that is, neither natural-sediment and pore-water characteristics nor unmeasured contaminants affected the test organisms. It is possible that sediment collection and handling may have induced chemical changes, confounding interpretation of toxicity tests.
Aerobic biodegradation of a silver-bearing photoprocessing wastewater
Authors: Pavlostathis Spyros G , Maeng Sung Kyu
Published: March 2010

Aerobic biodegradation of a photoprocessing wastewater (with a silver level attained after silver recovery) was assessed using fill-and-draw activated sludge reactors. The extractability of silver from the resulting waste activated sludge was also determined. Simulated, fixer-derived wastewater was fed to the activated sludge reactors at a volumetric loading level of 40% along with an organic mixture. The biodegradation of the organic mixture was not affected by the photoprocessing wastewater. Thiosulfate was completely oxidized to sulfate. Complete conversion of ammonia to nitrite was observed, but much lower levels of nitrate were detected in the fixer and fixer-plus-silver-amended reactors, as compared to the control reactor (fed only the organic mixture). Silver at an influent total silver concentration of 1.85 mg/L did not result in any adverse effects on the activated sludge process. Filtered (through a 0.2-μm membrane filter) effluent silver concentrations were below the detection limit of 0.01 mg/L. Practically, all silver was associated with the sludge solids and the mean steady-state silver content of the sludge was 1.84 mg Ag/g mixed liquor suspended solids. When fresh sludge and aerobically digested sludge solids were subjected to the toxicity characteristic leaching procedure, the resulting silver concentration was at least 40 times lower than the regulatory limit of 5 mg Ag/L.
Reactivity of Ag+ ion with thiol ligands in the presence of iron sulfide
Authors: Adams Nicholas W.H , Kramer James R
Published: March 2010

Dissolved silver (Ag) in the presence of amorphous iron sulfide(FeS) rapidly equilibrates to ultra-trace levels ( ∼5 ng/L), which agrees with equilibrium calculations based on Ag2S solubility. This finding, along with the authors' discovery that crystalline Ag2S (acanthite) precipitates rapidly under supersaturated conditions, suggests that a discrete Ag-S phase is formed. Furthermore, potential interferences (Cl−, Cu2+, and dissolved organic carbon) show no effect on the Ag-FeS system. Only the presence of organosulfur (thiol) ligands at 10−3 to 10−4 M result in increased dissolved silver. Agreement between calculations and measured values were good for 1.8 × 10−4 M 3-mercaptopropanoic acid; however, calculations predicted higher dissolved silver than measured values for higher thiol levels, possibly due to Ag-thiol binding to FeS.
Copper tolerance in iron-reducing bacteria: Implications for copper mobilization in sediments
Authors: Markwiese James T , Meyer Joseph S , Colberg Patricia J.S
Published: March 2010

Iron-reducing bacteria enriched from a Cu-contaminated sediment were more tolerant of Cu adsorbed to hydrous ferric oxide (HFO) than were pristine-sediment bacteria. Tolerance was enhanced by increasing the Cu concentration in the culture medium over time, enabling the bacteria to begin reducing Cu-contaminated HFO sooner and at a faster rate than Cu-intolerant bacteria. Copper tolerance confers a greater ability to reduce contaminated HFO and may result in a greater potential for Cu mobilization in sediments.
Acute toxicity and toxicokinetics of 4-heptylphenol in juvenile atlantic cod (Gadus morhua L.)
Authors: Tollefsen Knut-Erik , Ingebrigtsen Kristian , Olsen Anders Johny , Zachariassen Karl Erik , Johnsen Ståle
Published: March 2010

Heptylphenol has been detected in produced water from various oil production platforms in the Norwegian sector of the North Sea and may be of environmental concern due to hydrophobic properties and slow biodegradation in the marine environment. The n-octanol/water partition coefficient of 4-heptylphenol (4-HP) was estimated by a high-performance liquid chromatographic correlation analysis. Acute toxicity and toxicokinetics of 4-HP in juvenile Atlantic cod (Gadus morhua L.) were investigated in flow-through exposure systems using unlabeled and 14C-labeled 4-HP, respectively. The results show that 4-HP was moderately hydrophobic (log Kow = 4.5) and toxic to juvenile cod (96 h LC50 = 2.9 μmol/L). The toxicokinetics of 4-HP was calculated using a one-compartment first-order kinetic (1CFOK) model (k1 = 29.94 ± 1.83, k2 = 0.052 ± 0.011/h, t95 ≈ 58 h and t1/2 ≈ 13 h). The values obtained corresponded to a steady-state and kinetic bioconcentration factor (BCF) of 555 and 578, respectively. The distribution pattern of 4-HP (and/or metabolites) at steady state and after 96 h of recovery in uncontaminated seawater was dominated by the gastrointestinal system possibly owing to biotransformation and elimination through these organs. The results also revealed that neither 4-HP nor possible metabolites bind to macromolecules or tissue structures in the fish.
Structural influences of low-molecular-weight dissolved organic carbon mimics on the photolytic fate of atrazine
Authors: Hapeman Cathleen J , Bilboulian Susanna , Anderson Brent G , Torrents Alba
Published: March 2010

The fate of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) was examined in the presence of dissolved organic carbon (DOC) mimics to discern the effect of the various structural characteristics of DOC with respect to direct photolysis and transformation via a photoinitiated nitrate-mediated hydroxy radical process (indirect photolysis). Experiments were conducted with coniferyl alcohol, 2-octanol, oxalic acid, pyrogallol, quinone, and salicylic acid. All mimics except octanol and coniferyl alcohol caused an increase in the atrazine degradation rate when no nitrate was present. A decrease in atrazine degradation in indirect photolysis was observed for coniferyl alcohol, octanol, pyrogallol, and salicylic acid, whereas the rate increased with oxalic acid and quinone. Examination of the product ratios showed a dependence of the chemical activity (photosensitizer, OH· radical scavenger or OH· generator) on structure. Results revealed that structural aspects of DOC, in addition to concentration, must be considered when predicting the photolytic fate of pesticides.
Comparison of in vitro submitochondrial particle and Microtox® assays for determining the toxicity of organotin compounds
Authors: Argese Emanuele , Bettiol Cinzia , Ghirardini Annamaria Volpi , Fasolo Matteo , Giurin Gianumberto , Ghetti Pier Francesco
Published: March 2010

The toxicity of 14 organotin compounds was investigated by means of two short-term in vitro bioassays, the submitochondrial particle (SMP) test and the Microtox® test. The first bioassay makes use of SMPs and is based on the effects of toxicants on reverse electron transport, which is induced by adenosine triphosphate and succinate at the first site level of the respiratory chain. Microtox is a well known test system that uses marine luminescent bacteria and quantifies toxicity by measuring the reduction of luminescence caused by toxic chemicals. Very good agreement was observed between the median effective concentration (EC50) values determined for organotin compounds by means of the two bioassays. Toxicity depended on both the number and kind of organic substituents bound to the tin atom. It followed the order triorganotins > diorganotins ≈ tetraorganotins > monoorganotins. Within each series, butyltin and phenyltin compounds exhibited the highest toxicity. Microtox and SMP EC50 values were successfully correlated with toxicity data for aquatic organisms, demonstrating the usefulness of these bioassays as prescreening or complementary tools for monitoring aquatic toxicity. Moreover, to investigate the suitability of the two assays in providing information on the mechanism of toxic action of organotins, EC50 values were correlated with various physicochemical and structural parameters of the tested compounds. The results obtained showed that these parameters are poor descriptors of organotin toxicity; in particular, the poor correlations found between EC50 values and log Kow could be ascribed to the fact that different modes of action govern the biological activity of mono-, di-, tri-, and tetraorganotin compounds, respectively.
Sequestration of DDT and dieldrin in soil: Disappearance of acute toxicity but not the compounds
Authors: Robertson Boakai K , Alexander Martin
Published: March 2010

House fly (Musca domestica), fruit fly (Drosophila melanogaster), and German cockroach (Blattella germanica) were used to assay the acute toxicity of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and dieldrin aged in sterile soil. Significant reduction in mortality of the insects was observed in DDT- and dieldrin-amended soil samples aged for 30 d, and toxicity decreased further with additional aging. After 270 d, DDT and dieldrin were no longer toxic to house flies, and dieldrin was no longer toxic to fruit flies and cockroaches at 120 d. Nevertheless, 84.7% of the DDT and 92.1% of the dieldrin was recovered from the soil by vigorous extraction after 180 and 270 d, respectively. The results show that toxic chemicals residing in soil become less toxic with time, the extent of decline in bioavailability may differ among different species, and vigorous extraction may grossly overestimate toxicity.
Volatility of chlorinated n-alkanes (C10–C12): Vapor pressures and Henry's law constants
Authors: Drouillard Ken G , Tomy Gregg T , Muir Derek C G , Friesen Ken J
Published: March 2010

Polychlorinated n-decanes, n-undecanes, and n-dodecanes with chlorine numbers of two to six were utilized to assess physicochemical properties of short-chain (C10–C13) chlorinated paraffins. Subcooled-liquid vapor pressures (Ps), determined using the vapor pressure–gas-liquid chromatography correlation technique, ranged from 1.4 × 10−4 to 0.50 Pa at 25°C among the compounds studied. Vapor pressures tended to decrease with increasing carbon chain length and degree of chlorination according to the correlation: log P = −0.353(C No.) — 0.645(0 No.) + 4.462. Henry's law constants (Hs), determined using gas-sparging techniques, ranged from 17.7 to 0.68 PaṁmVmol for terra- and pentachloro congeners at 23°C. The Henry's law constants for 1,10-dichlorodecane and 1,12-dichlorododecane, 499 and 648 Paṁm3/mol respectively at 25°C, were calculated from experimentally determined vapor pressures and water solubilities. Henry's law constants decreased with increasing degree of chlorination.
Bioaccumulation of lipophilic substances in fish early life stages
Authors: Petersen Gitte I , Kristensen Preben
Published: March 2010

Accumulation of 14C-labeled polycyclic aromatic hydrocarbons, naphthalene, phenanthrene, pyrene, and benzo(a)pyrene and polychlorinated biphenyl (PCB) congeners PCB 31 and PCB 105 with a log octanol/water partition coefficient (Kow) range from 3.37 to 6.5 was investigated in eggs and larvae of zebra fish (Brachydanio rerio), and in larvae of cod (Gadus morhua), herring (Clupea harengus), and turbot (Scophthalmus maximus). Significant differences in the uptake and elimination rate constants between eggs and larvae of zebra fish were seen. The low rate of uptake and the lower elimination rate of eggs did, however, lead to bioconcentration factors (BCFs) comparable to those for larvae. As biotransformation of xenobiotics in embryonic and larval stages was indicated to be insignificant compared to juvenile/adult stages, body burdens of readily biotransformed chemicals may be higher in fish early life stages. Because weight and lipid content did not differ much between the investigated species, the main reason for the variability in BCFs between marine species (cold water species) and freshwater species (warm water species) was considered to be caused by differences in exposure temperatures that affect the degree of biotransformation. Due to the smaller size of larvae and thus an increased total surface of the membranes per unit fish weight, steady-state conditions were reached at a faster rate in early life stages than in juvenile/adult life stages. The lipid-normalized bioconcentration factors (BCFL) were linearly related to Kow, but BCFL was, in general, higher than Kow, indicating that octanol is not a suitable surrogate for fish lipids. Differences in bioconcentration kinetics between larvae and juvenile/adult life stages are considered to be the main reason for the higher sensitivity, with respect to external effect concentrations, generally obtained for early life stages of fish.
A new technique for determining the sublethal toxicity of pesticides to the vesicular-arbuscular mycorrhizal fungus Glomus intraradices
Authors: Wan Michael T , Rahe James E , Watts Ronald G
Published: March 2010

Sublethal toxicity of selected reference pesticides and solvents to the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus intraradices growing on root inducing transferred DNA (Ri T-DNA)–transformed roots of Daucus carota was determined using a new bioassay technique. Determinations were made on the concentration causing 50% inhibition of growth and development (IC50) to G. intraradices of acetone, methanol, benomyl, chlorothalonil, copper sulfate, dimethoate, glyphosate, and aminomethylphosphonic acid. Effects of these test materials on carrot roots and colonization by G. intraradices were also evaluated. The potential for using G. intraradices as an indicator species and the new technique as a standard test to determine the toxicity of pesticides on VAM fungi for the evaluation of ecosystem impact is discussed.
Accumulation of chromium by a population of mussels (Mytilus edulis (L.)) exposed to leather tannery effluent
Authors: Walsh Andrew R , O'Halloran John
Published: March 2010

The accumulation of chromium was investigated at the tissue and ultrastructural level in mussels (Mytilus edulis (L.)) in an estuary receiving leather tannery effluent and at a reference site. Mussels were also reciprocally transplanted between the estuaries to follow short-term patterns of accumulation and depuration, respectively. The digestive gland was found to accumulate the highest concentrations of chromium in transplanted mussels after 12 months. However, in native mussels (>8 years old), the gill contained the highest concentrations. The general trend in the chromium concentrations of native mussels was: gill > kidney > digestive gland > mantle > adductor muscle. Concentrations of chromium in the gill of mussels close to the tannery outfall were in the range 400 to 1,000 μg/g dry weight, compared to a maximum of 6 μg/g in reference mussels. Seasonally in chromium concentrations was seen at both sites with an early spring maximum evident in reference mussels that could be linked to spawning and an early summer peak in concentrations in the contaminated estuary, possibly as a result of augmented feeding or increased discharges. Relationships between tissue concentrations were also studied and a high correlation occurred between some tissues, for example, digestive gland–kidney and gill–adductor muscle. Depuration was generally slow in mussels transplanted out of the Colligan Estuary, although the digestive gland lost the most chromium. Therefore, it is suggested that two pools of chromium accumulation exist in the contaminated mussels, that is, via the gills (slow) and via the digestive gland (fast). At the cellular level, chromium was found in both particulate (lysosomal) and cytosolic fractions. In the gill, particulate chromium was associated with calcium and phosphorus, whereas chromium was detected in sulfur-dominated granules in the kidney. In the cytosol, binding to a high molecular weight component occurred in the gill, whereas binding in the digestive gland cytosol was dominated by a poorly resolved low molecular weight component. In addition, chromium is apparently detoxified by a separate pathway compared with iron or zinc, as judged by the differential cytosolic and lysosomal affinities of these metals.
Temperature, physiological time, and zinc toxicity in the isopod Porcellio scaber
Authors: Donker Marianne H , Abdel-Lateif Hala M , Khalil Mohamed A , Bayoumi Bayoumi M , Van Straalen Nico M
Published: March 2010

Temperature is an important controlling factor in the metabolism of ectotherms, and it may interact with the toxicity of heavy metals in a variety of ways. In this work, a study on the effect of different zinc concentrations (0.3, 13, 26, and 40 μmol/g dry litter) on growth (body weight) of the isopod Porcellio scaber was conducted using four temperature levels (12, 16, 20, and 24°C). The results demonstrated a significant effect for both zinc and temperature on the growth rate; the interaction between zinc and temperature was also significant. The Arrhenius function was used to describe the temperature–growth rate relationship, from which estimates for the activation energy were derived. A tendency for activation energy to decrease with increasing zinc concentration was observed. Isopods exposed to 13 μmol Zn/g had the highest activation energy and the highest growth rate. To analyze the effect of temperature on the internal body concentration of zinc, the exposure time was transformed into physiological time, calibrated at 15°C, for all experimental groups using the activation energies estimated earlier. The rate of zinc accumulation was derived from the relationship between internal body concentration and physiological exposure time. Differences between isopods cultured at different temperatures could be explained well by the effect of physiological exposure time. The interaction between temperature and zinc toxicity seems to be due not to increased accumulation of zinc at higher temperatures as such but to a physiological interaction with the energy metabolism.
Bioassay technique using nonspecific esterase activities of tetrahymena pyriformis for screening and assessing cytotoxicity of xenobiotics
Authors: Bogaerts Philippe , Senaud Jean , Bohatier Jacques
Published: March 2010

A simple and rapid test for screening and assessing the cytotoxicity of xenobiotics was developed with Tetrahymena pyriformis. The method estimates the activities of nonspecific esterases of a cell by concentrating within it a specific amount of fluorescence associated with fluorescein dye. The 1-h median effective concentration (EC50) values of 10 inorganic and eight organic substances are presented and compared to those of three other bioassays: the conventional T. pyriformis proliferation rate 9-h median inhibitory concentrations, the Microtox® 30-min EC50s, and the Daphnia magna 4-methylumbelliferyl β-D galactoside 1-h EC50s. A highly significant correlation was found between the results obtained with the fluorescein diacetate test and those obtained with the growth inhibition and Microtox tests. This in vivo enzymatic test showed high sensitivity to all compounds tested except Cr6+ and sodium dodecyl sulfate.
Long-term changes in sediment barium inventories associated with drilling-related discharges in the Santa Maria Basin, California, USA
Authors: Phillips Charles , Evans John , Hom Wilson , Clayton John
Published: March 2010

Nine-year (1986–1995) records of barium (Ba) concentrations in surficial, subsurface, and suspended sediments near offshore oil and gas platforms in the Santa Maria Basin, California, USA, were analyzed to evaluate temporal trends related to drilling activities. These trends provide important information on the long-term effects of drilling discharges on geochemical conditions. Drilling during the 1986 through 1989 (phase II) monitoring period resulted in significant changes in Ba concentrations in suspended particles and surficial sediments, whereas the relatively shorter 1993 through 1994 (phase III) drilling operations resulted in only minor increases in Ba concentrations in suspended sediments. Residual excess Ba was present in some sediments within 500 m of the platforms at concentrations up to an order of magnitude above background. These elevated levels probably were associated with cuttings particles deposited near the base of the platforms. Calculated excess Ba in sediments within 500 m of the platforms represented 6 to 11% of the total Ba discharged during the two drilling periods.
Coupled effects of nonlinear, rate-limited sorption and biodegradation on transport of 2,4-dichlorophenoxyacetic acid in soil
Authors: Hu Max Q , Brusseau Mark L.
Published: March 2010

The transport and fate of many contaminants in subsurface systems can be influenced by several coupled processes, such as nonlinear, rate-limited sorption and biodegradation. We investigated the transport in soil of a model organic compound, 2,4-dichlorophenoxyacetic acid (2,4-D), influenced by nonlinear, rate-limited sorption and biodegradation. Miscible displacement and batch sorption experiments were conducted using a wide range of solute concentrations to investigate the impact of concentration-dependent behavior on transport. The sorption isotherm was approximately linear at a low concentration, and nonlinear over the extended range of concentrations. Results from the transport experiments, with the fitted N values approaching 1 at low input concentrations, were consistent with the batch sorption study. Nonlinear sorption significantly influenced the position of the breakthrough curves because of concentration-dependent retardation. However, although both nonlinear and rate-limited sorption influenced the shape of the breakthrough curves, the impact of rate-limited sorption was greater. The effective travel time of 2,4-D transport is influenced by synergistic interactions between sorption and biodegradation. For example, the sequential rightward shift of the breakthrough curves with decreasing input concentration, due to nonlinear sorption of 2,4-D, is enhanced by biodegradation.
Effect of pyrophosphate on the dechlorination of tetrachloroethene by the Fenton reaction
Authors: Wang Xiaojiang , Brusseau Mark L
Published: March 2010

The effectiveness of Fenton's reagent for the remediation of contaminated sandy soils is affected by the precipitation and sorption of Fe species in soil/water systems. We investigated the ability of pyrophosphate to maintain Fe in solution and thus enhance the dechlorination of tetrachloroethene (PCE) by the Fenton reaction. The results of the experiments showed that pyrophosphate could significantly increase the concentrations of Fe in aqueous solutions and enhance the dechlorination of PCE. The dechlorination rate of PCE in the presence of pyrophosphate was found to decrease with time, which was attributed to both the conversion of Fe(II) to Fe(III) and the decrease of aqueous Fe concentration. In comparison to organic chelating agents, pyrophosphate appeared to be more stable and thus catalyzed the dechlorination of PCE for a longer time. The extended dechlorination (>120 h) was attributed to the solubilization of Fe and the stabilization of H2O2 caused by the addition of pyrophosphate.
Evaluating environmental persistence
Authors: Webster Eva , Mackay Don , Wania Frank
Published: March 2010

Environmental persistence is an important consideration when assigning priorities to chemical contaminants. It has been proposed that pass/fail half-life criteria be established for the media of air, water, soil, and sediment. The feasibility of applying such criteria is discussed. It is shown that there are severe problems in estimating these half-lives. Additionally, it is shown that the overall environmental half-life or persistence in a multimedia environment is also a function of the mode of entry of the chemical and its partitioning properties. Examples of potential misclassification are presented. An alternative two-tiered procedure is suggested in which the first tier considers only media half-lives and the second tier considers the overall half-life as deduced by mass-balance models. Furthermore, the overall persistence calculated in the second tier should be given as a distribution rather than a single value. This procedure enables chemicals to be compared, avoids undue reliance on relatively unimportant half-lives, and is regarded as a truer depiction of actual chemical persistence in the environment.
Quantitation of Aroclors using congener-specific results
Authors: Newman John W , Becker Jonathan S , Blondina Gloria , Tjeerdema Ron S
Published: March 2010

As analytical capabilities have increased over the last 30 years, the standard approach applied to the analysis of polychlorinated biphenyls (PCBs) has slowly shifted from technical grade approximation to component-based analyses. This practice, although improving the quality and toxicologic relevance of the resulting data, has limited the historical database as a useful comparative set for current environmental research and is divergent from existing regulatory practices. Aroclor conversion factors have been calculated for each of 14 PCB congeners (International Union for Pure and Applied Chemistry [IUPAC] numbers 18, 28, 31, 99, 118, 128, 138, 149, 153, 180, 194, 195, 201, and 203), allowing quantification of PCB profiles as Aroclors 1248, 1254, and 1260 using measurements of these congeners. The three specified Aroclors are the dominant forms observed in the California marine environment. Speciation is accomplished by comparing characteristic congener ratios in the technical mixtures (31:118 for 1248 and 1254 and 118:203 for 1260) with those found in samples, providing a means for objectively minimizing biases introduced by cochromatographing Aroclor mixtures. The outlined procedure is shown to accurately detect, speciate, and quantify mixtures of multiple Aroclors. Additionally, comparing the predicted and actual concentration of PCB 153 in a sample provides a working index of weathering for these Aroclors.
Mammalian and teleost cell line bioassay and chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations in lake trout (Salvelinus namaycush) from Lake Superior and Lake Ontario, North America
Authors: Whyte Jeff J , van den Heuvel Mike R , Clemons Janine H , Huestis Susan Y , Servos Mark R , Dixon D George , Bols Niels C
Published: March 2010

For livers of lake trout from three Great Lakes sites, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent concentrations (TEQs) were determined in four ways. Bioassay-derived (BD) TEQs were measured with rat (H4IIE) and rainbow trout (RTL-W1) cell lines, and chemistry-derived (CD) TEQs were calculated with TCDD equivalency factors (TEFs) derived with H4IIE and RTL-W1. Generally, BD-TEQs and CD-TEQs for individual samples did not differ significantly for either H4IIE or RTL-W1, indicating that all of the AhR-active compounds in a sample were accounted for by the congener analysis and that these compounds acted in an additive fashion in both mammalian and piscine systems. However, contributions of individual chemicals to overall CD-TEQs differed with H4IIE and RTL-W1 TEFs, and for some individual samples, TEQs did depend on the method used. Hepatic TEQs and ethoxyresorufin-O-deethylase (EROD) levels differed significantly between sites. For TEQs, the order was Glenora > Jackfish Bay > Black Bay; for EROD activity, the order was Jackfish Bay > Glenora = Black Bay. No correlation was found between hepatic TEQs and EROD activity, which suggests that the two measurements are evaluating different but related consequences of contaminant exposure.
Reproductive toxicity and disposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin in adult brook trout (Salvelinus fontinalis) following a dietary exposure
Authors: Tietge Joseph E , Johnson Rodney D , Jensen Kathleen M , Cook Philip M , Elonen Gregory E , Fernandez Joseph D , Holcombe Gary W , Lothenbach Douglas B , Nichols John W
Published: March 2010

Ault brook trout (Salvelinus fontinalis) were exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with a contaminated trout pellet diet to determine the effects of TCDD on reproduction, to document tissue-specific TCDD distribution, and to establish the maternally derived dose of TCDD to the F1 generation. Five treatment groups and a control were exposed to achieve targeted whole body TCDD concentrations of 0, 75, 150, 300, 600, and 1,200 pg TCDD per gram fish. Net dietary assimilation of TCDD was estimated to be 89% of the applied dose, and the distribution of TCDD generally followed the distribution of lipids in liver, gonad, fat, blood, and muscle. Depuration could not be measured over 81 d, but a hypothetical depuration rate was estimated to be 0.002 d−1 assuming 100% dietary assimilation. The concentration of TCDD in ovaries and spawned eggs was estimated to be 61 and 39% of the whole body TCDD concentrations, respectively. Survival, growth, gonadal development, and egg production were not affected in any treatment. The onset of spawning was delayed by 13 d in the highest treatment group, suggesting that TCDD might have affected ovulation. Otherwise, the adult life stage was not as sensitive to TCDD as the early life stage.
Historical impacts of environmental regulation of silver
Authors: Purcell Thomas W , Peters Jennifer J
Published: March 2010

Exposure to silver, and hence its possible environmental effects, has been regulated since the 1960s. Rules were first developed in the United States to protect against potential negative effects to humans due to ingestion of drinking water containing silver. As regulations for other environmental media were developed, silver was generally included because of its designation as a drinking water chemical of concern. Ambient water quality criteria were developed based on the toxic action of ionic silver. In the early 1990s the U.S. Environmental Protection Agency's Office of Drinking Water downgraded silver from a primary to a secondary maximum contaminant level because the effects of exposure to silver were judged to be cosmetic. Regulations pertaining to solid waste, surface waters, and occupational exposure have not been changed, but may be changed in the near future as the fate and toxic mechanisms of silver become better understood.
Effects of altering freshwater chemistry on physiological responses of rainbow trout to silver exposure
Authors: Bury Nicolas R , McGeer James C , Wood Chris M
Published: March 2010

The influence of different water Cl− (50–600 μM), Ca2+ (50–1, 500 μM), Na+ (50–1, 500 μM), or dissolved organic carbon (DOC, 0.31–5 mg/L) levels on silver-induced physiological and biochemical perturbations of rainbow trout were investigated. Fish were acclimated to soft water (50 μM; Cl−, Ca2+, and Na+), then exposed to 3.7 μg/L Ag (as AgNO3) for 6 h, which resulted in a reduction in Na+ influx from the water, an inhibition of gill sodium- and potassium-activated adenosine triphosphatase (Na+/K+-ATPase) activity, and an accumulation of silver on the gills. Increasing the water Cl− or DOC levels ameliorated the silver toxicity. However, increasing water Ca2+ or Na+ concentration did not reduce the silver-induced physiological and biochemical perturbations. The free silver ion (Ag+) concentrations (calculated from MINEQL+, a geochemical speciation computer program) showed a negative correlation with the Na+ influx rates and gill Na+/K+-ATPase activity. However, gill silver levels did not correlate to Ag+ concentrations and no correlation was found between gill silver levels and either Na+ influx rates or gill Na+/K+-ATPase activity. These results support the notion that the [Ag+] concentration is of major importance when assessing silver toxicity in fish, and that this should be taken into account in regulatory strategies for silver in the natural environment.
Physiology and modeling of mechanisms of silver uptake and toxicity in fish
Authors: Wood Chris M , Playle Richard C , Hogstrand Christer
Published: March 2010

In this review, we outline the physiological and toxicological effects of silver (Ag) in freshwater and marine fish. For freshwater fish, the acute toxicity of Ag appears to be caused solely by ionic Ag+ interacting at the gills, inhibiting basolateral Na+, K+-ATPase activity. Disruption of this enzyme inhibits active Na+ and Cl− uptake and therefore osmoregulation by the fish. Silver is much less toxic to marine fish, mainly because ionic Ag+ is complexed by Cl−, but the mechanisms of acute toxicity and the toxic species of Ag are poorly understood. Osmoregulatory failure occurs in marine fish exposed to high concentrations of Ag, and the intestine appears to be a primary toxic site of action, perhaps along with a gill component. Modeling approaches to calculate Ag interactions at biological surfaces are used to illustrate the effects of water chemistry on Ag speciation and therefore toxicity to freshwater and marine fish. In these models, the most important components affecting Ag speciation are the complexing agents Cl− and dissolved organic matter followed by the competing agents Na+ and Ca2+, although a particulate component may be important to incorporate into the models in future. More precise knowledge of the actual toxic sites of Ag is necessary if we are to fully understand the effects of waterborne Ag in the environment.
Use of Ulva Lactuca to distinguish pH-dependent toxicants in marine waters and sediments
Authors: Ho Kay T , Kuhn Anne , Pelletier Marguerite C , Burgess Robert M , Helmstetter Andrea
Published: March 2010

Ulva lactuca (sea lettuce) is a cosmopolitan marine attached green seaweed capable of sequestering high environmental levels of ammonia. Ammonia can be acutely toxic to marine organisms and is often found in dredged sediments from highly industrial areas or from areas with high carbon inputs. For the purposes of dredged sediment disposal as well as in determining causes of toxicity in complex mixtures, it is important to distinguish ammonia toxicity from the toxicity of other compounds. The use of U. lactuca to selectively remove ammonia from waters and sediments as part of a toxicity identification and evaluation (TIE) procedure was evaluated. Ulva lactuca lowered concentrations of total ammonia from 75 to 17 mg/L in <8 h in water-only exposures. This treatment also reduced 48-h amphipod mortality from 75 to 20%. In whole sediments, U. lactuca lowered interstitial water concentrations of ammonia from 60 to 20 mg/L, while keeping overlying water concentrations below detectable limits (<1 mg/L). To determine the limitations of the U. lactuca method to selectively remove ammonia from solution, metal and organic accumulation experiments were performed. Ulva lactuca generally took up <15% of metals present, with most of the exposures resulting in less than a 10% uptake. In contrast, U. lactuca removed 77% of lindane and 95% of fluoranthene. Results of a TIE conducted on sediments from an industrial marine harbor indicated U. lactuca was useful, in conjunction with other procedures, in categorizing ammonia as a sediment toxicant.
Bioconcentration, biotransformation, and chronic toxicity of sodium laurate to zebrafish (Danio rerio)
Authors: van Egmond Roger , Hambling Susan , Marshall Stuart
Published: March 2010

The chronic toxicity of sodium laurate (dodecanoic acid, sodium salt; CAS 629-25-4) to zebrafish (Danio rerio) was determined in a 28-d growth rate study. The laurate did cause lethal effects, but a reduction in growth was not observed at sublethal exposure concentrations. The 15-d median lethal concentration was 7.6 mg/L, which is similar to the theoretical and measured solubility limit of laurate under the test conditions. The 28-d no-observed-effect concentration (lethality) was 2 mg/L, whereas growth was not impaired at 6.4 mg/L in survivors after 28 d. Laurate was extensively biotransformed to metabolites, including less polar compounds, possibly triacylglycerols. At the end of the exposure period, which was considered long enough for steady state to be achieved, the bioconcentration factor of laurate was estimated to be 255 L/kg. Body burdens of nonmetabolized laurate for surviving fish were up to 10-fold higher (2.7–8.7 mmol/kg) than the chronic critical (sublethal) body residues (0.2–0.8 mmol/ kg) proposed for nonpolar or polar narcotics.
New testing apparatus for assessing interactive effects of suspended solids and chemical stressors on plankton invertebrates
Authors: Herbrandson Carl , Bradbury Steven P , Swackhamer Deborah L
Published: March 2010

To better predict and interpret the responses of aquatic organisms to environmentally relevant chemical exposures, it is necessary to investigate the combined effects of physical (e.g., suspended solids) and chemical stressors. One of the limitations in investigating suspended solids-chemical interactions has been the lack of an appropriate testing system. The specific objective of the current study was to develop and assess a suspended solids testing apparatus (SSTA) for studies on the combined effects of suspended solids and chemicals on aquatic invertebrates. The SSTA was designed to permit the assessment of varying suspended solids concentrations on Daphnia magna at a constant freely dissolved concentration of a compound. The system was also designed to facilitate the control of exposure variables without the need for large numbers of replicates and chemical analyses. The experiments reported here demonstrate that the SSTA is effective for assessing the combined or interactive effects of suspended solids and a chemical stressor on aquatic organisms.