bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of soil type, prepercolation, and ageing on bioaccumulation and toxicity of zinc for the springtail Folsomia candida
Authors: Smit C Els , Van Gestel Cornelis A M
Published: March 2010

Soil properties are a major influence on the bioavailability and toxicity of metals and represent one of the important factors that complicate the extrapolation of results from laboratory tests to field situations. The influence of soil characteristics and way of contamination on the bioaccumulation and toxicity of zinc was investigated for the springtail Folsomia candida, and the applicability of chemical extraction techniques for the prediction of zinc uptake and toxicity was evaluated. Bioaccumulation of zinc in F. candida was related to water-soluble zinc concentrations, and uptake was dependent on the test soil used. Effects of zinc for F. candida could not be fully explained by bioaccumulation. This indicates that the existence of a fixed internal threshold concentration of zinc above which physiological functions are impaired is not likely for F. candida. In freshly contaminated soils, zinc toxicity was related to organic matter and clay content of the soil; however, the use of these soils overestimated the effects of zinc for F. candida by a factor of 5 to 8 compared to a test soil that was subjected to ageing under field conditions for 1.5 years. Equilibration of the zinc contamination by percolating the soils with water before use in the toxicity experiment strongly reduced the difference in zinc toxicity between laboratory-treated and aged soils. Water-soluble concentrations are most appropriate to predict effects of zinc on reproduction of F. candida in soils with unknown contamination histories. For laboratory toxicity tests, it is recommended to percolate soils with water after contamination and to include an equilibration period prior to use to achieve a more realistic exposure situation.
Mercury distribution in poplar creek, Oak Ridge, Tennessee, USA
Authors: Campbell Kym Rouse , Ford Clell J , Levine Daniel A
Published: March 2010

As a result of the lithium-isotope separation process used in the production of thermonuclear fusion weapons during the mid-1950s and early 1960s, 150 t of mercury were released into Poplar Creek (via East Fork Poplar Creek) in Oak Ridge, Tennessee, USA. This project was performed as part of a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) remedial investigation to define the nature and extent of mercury contamination in Poplar Creek. Ultraclean sampling techniques and ultrasensitive analytical methods were used to determine methylmercury and inorganic mercury concentrations in surface water, sediment, and pore water from Poplar Creek. Total methylmercury and inorganic mercury concentrations (0.08–0.7 ng/L and 0.4–560 ng/L, respectively) in surface water from reaches downstream from the East Fork Poplar Creek confluence were significantly higher (p < 0.05) than the upstream reference reach (0.05–0.3 ng/L and 0.1–27 ng/L, respectively). Concentrations in surface water increased with distance downstream from the source (East Fork Poplar Creek), which was opposite of expected results. Sediment methylmercury and inorganic mercury concentrations also increased with the distance downstream from the source and were highest near the mouth of Poplar Creek (1.0–12 ng/g and 630–140,000 ng/g, respectively). High concentrations in surface water and sediment near the mouth of Poplar Creek appear to be a result of sediment deposition and resuspension, apparently caused by the stronger Clinch River current acting as a barrier and its backflow into Poplar Creek as a result of hydropower operations.
Determination of Henry's law constants by equilibrium partitioning in a closed system using a new in situ optical absorbance method
Authors: Allen John M , Balcavage Win X , Ramachandran B R , Shrout Anthony L
Published: March 2010

A new method for measurement of thermodynamic Henry's law constants (H) is reported. In this method, the optical absorbance of a dilute aqueous solution containing an organic compound is followed with time as the compound partitions into the air above the solution in a sealed vessel. The change in optical absorbance (i.e., change in concentration) and the vapor to liquid volume ratio of the vessel are then used to calculate the value for H. The concentration of the organic compound in the aqueous and vapor phases need not be known. This method allows the approach to equilibrium to be observed in real time so that attainment of equilibrium is readily apparent. This method works particularly well for water-soluble compounds having low vapor pressures. The applicability of this method is limited to compounds that exhibit significant optical absorbance in the ultraviolet and visible regions of the electromagnetic spectrum. Values for H and their temperature dependencies measured using this new method are reported for methacrolein, methyl vinyl ketone, benzaldehyde, and acetophenone. Values for H are also reported for benzene, toluene, and ethylbenzene at 298 K. All reported H data are compared with previously reported values.
Estimating the aqueous solubilities of individual chlorinated n-alkanes (C10–C12) from measurements of chlorinated alkane mixtures
Authors: Drouillard Ken G , Hiebert Tim , Tran Phuong , Tomy Gregg T , Muir Derek C G , Friesen Ken J
Published: March 2010

Water solubilities of several chlorinated n-alkanes, with carbon chain lengths ranging from C10 to C12, were determined from simple synthetic mixtures because few of these compounds are available in pure form. The apparent solubilities (S′w) of several chlorinated n-decanes in the mixture were determined using the generator column technique. To assess the effect of the mixture on S′w, the aqueous solubility and activity coefficient (γorg) of a reference compound, 1,10-dichlorodecane, were determined as a function of its mole fraction in the same synthetic mixture. The mixture exhibited a cosolute effect on the solubility of dichlorodecane, with apparent solubilities decreasing linearly with decreasing mole fraction. The results were used to correct the apparent solubilities of terra- and pentachlorodecanes determined from the synthetic mixture, thereby providing estimates of the true subcooled-liquid aqueous solubilities of these compounds. The solubilities of polychlorinated decane, undecane, and dodecane congeners were also estimated using subcooled-liquid vapor pressures and Henry's law constants determined from previous experiments. The two methods yielded comparable estimates, within a factor of 1.5, of the true solubilities of polychlorinated decanes. Water solubilities for selected chlorinated n-alkane congeners among the three carbon chain lengths ranged from 22.4 to 975 μg/L and showed a trend of increasing solubility with increasing degree of chlorination to chlorine number five. The data, providing some of the first physical properties of individual isomers of C10 to C12 polychlorinated n-alkanes, may be useful in assessing the environmental behavior of chlorinated paraffins in general.
Assessment of metal inhibition of reductive dechlorination of hexachlorobenzene at a superfund site
Authors: Jackson W Andrew , Pardue John H
Published: March 2010

Laboratory studies were conducted to identify easily measured parameters that would predict the potential for metal inhibition in sediments co-contaminated by heavy metals and hexachlorobenzene (HCB) at the Petro Processors Superfund site. Metal inhibition was investigated using HCB-contaminated sediment and a range of added metal concentrations (1–1,000 mg/kg). Cadmium, Cu, Pb, and Zn all caused inhibition of HCB reductive dechlorination and methane production with inhibiting concentrations of Cd and Pb equivalent to those found in portions of the site. In the second phase of studies, laboratory experiments investigated the relationship between Cd and Pb availability on the kinetics of HCB degradation. Cadmium and Pb affected both dechlorination rates and lag times. In addition, Cd affected the appearance of lower chlorinated benzene metabolites. Inhibition of HCB dechlorination was well correlated to ratios of acid-volatile sulfide (AVS) to simultaneously extractable metals (SEM) and water-soluble Cd. Only treatments with a measurable concentration (>6 μg/L) of free, uncomplexed Cd exhibited inhibition. Lead inhibited HCB dechlorination at all concentrations tested (10–1,000 mg/kg) and inhibition did not correlate to either water-soluble Pb concentrations or AVS/SEM ratios. For both Cd and Pb, methane production was less sensitive to metals than HCB dechlorination, making production of methane a poor indicator of inhibition. Measurement of free, uncomplexed Cd was the best predictor of Cd inhibition while no suitable indicators were found for Pb. These results demonstrate the importance of metal bioavailability on the inhibition of reductive dechlorination.
Volatile fractions of landfill leachates and their effect on Chlamydomonas reinhardtii: In vivo chlorophyll a fluorescence
Authors: Brack Werner , Rottler Horst , Frank Hartmut
Published: March 2010

A method for identification of toxic volatile constituents of landfill leachates is presented that combines bioassay-compatible sample preparation, chemical analysis, and a bioassay based on in vivo chlorophyll a fluorescence of the green alga Chlamydomonas reinhardtii. Two major pathways of toxicity were identified by comparing fluorescence patterns: specific toxicity of hydrogen sulfide, and narcotic action of nonreactive organic compounds. For quantification, the contributions of identified compounds were calculated using toxic units. The ecotoxicologic relevance of volatile fractions from hazardous waste leachates was shown.
Mechanistic approach for estimating bioconcentration of organic chemicals in earthworms (oligochaeta)
Authors: Jager Tjalling
Published: March 2010

Earthworms (Oligochaeta) represent an important food source for many vertebrates and as a result, predators may encounter toxic effects via the food chain (secondary poisoning) from consumption of contaminated worms. Therefore, including an assessment of secondary poisoning in risk assessment procedures is advisable. In this study, a mechanistic model is presented for estimating bioconcentration of organic chemicals in earthworms. It is assumed that bioconcentration can be described by a thermodynamic partitioning between soil solids, soil water, and the resident organism's tissues. For most chemicals, the lipid phase is the dominant site for sorption in the earthworm, but for more hydrophilic compounds, the water phase may also play a role. Model predictions are compared to literature data that were derived from experiments with earthworms in water, laboratory experiments with various soils, and from field experiments. Without calibration, the model was able to accurately predict bioconcentration factors (BCFs) from experiments in water, indicating the applicability of this theoretical approach. However, BCFs in soil were consistently overestimated by the model (on average a factor of 5.6), which may be due to the absence of true equilibrium conditions in the soil-pore water-earthworm system. The collected experimental data reveal no net influence of uptake via soil ingestion, growth dilution, or sorption to dissolved organic carbon. Field data were more variable, but were generally consistent with the model. Nevertheless, before field data can be accurately predicted, the influences of chemical sorption, sorption kinetics, and earthworm behavior must be quantified under field conditions.
An environmental risk assessment profile of two synthetic polymers
Authors: Guiney Patrick D , Woltering Daniel M , Jop Krzysztof M
Published: March 2010

A number of environmental fate and effects studies on two distinctly different polycarboxylates were conducted as part of a product stewardship program. These studies led to the development of an environmental risk assessment for the two materials. Polymer emulsion (PE) is a typical anionic, styrene-acrylic polymer (MW 50,000–60,000) used in coating applications. Resin polymer (RP), insoluble at neutral pH but increasingly soluble at pH ≥8, is a neutral-charged, styrene-acrylic polymer (molecular weight 4,500–9,000) used primarily for graphic arts products. Some amount of both materials will enter the environment given their use and disposal patterns. Their environmental fate is driven by physical-chemical characteristics. Both polymers demonstrated low biodegradation and bioaccumulation potential and strong sorption to soils, sludge, and sediments in laboratory and/or field studies. Ecotoxicity test results on a variety of plant and animal species indicated a very low order of acute and chronic toxicity. The environmental risk assessment included characterization of exposure in relevant environmental matrices, characterization of adverse effects or hazards to receptors for which there are complete exposure pathways, and characterization of risk by comparison of predicted exposure levels to adverse effect threshold levels. Based on conservative exposure assumptions, the safety margins established in this assessment indicate that the use of PE and RP, in both commercial and household applications, presents a very low risk to aquatic organisms in the water column and sediments, as well as to terrestrial plants, invertebrates, and wildlife. These polymers are also compatible with wastewater and solid waste treatment systems.
Community level analysis of ecotoxicological field studies: I. Biological monitoring
Authors: Kedwards Timothy J , Maund Stephen J , Chapman Peter F
Published: March 2010

A number of multivariate techniques including nonmetric clustering, nonmetric multidimensional scaling, and principal components analysis were used to analyze data from a farm pond study in which the pyrethroid insecticide cypermethrin was aerially applied adjacent to the water body. The techniques were used to investigate the effects upon benthic and emerging macroinvertebrate communities prior to, during, and following application. Hydrosoil cypermethrin residue was strongly correlated with changes in community composition, and Diptera were found to be most affected by the perturbation. However, any deleterious effect upon chironomid communities was transient, with Chironomidae larvae rapidly recovering after application. The study illustrates how multivariate techniques can aid in the interpretation of biological monitoring studies in which an adequate control pond is unlikely to be available.
Pilot plant study to assess the fate of two volatile methyl siloxane compounds during municipal wastewater treatment
Authors: Parker Wayne J , Shi Jichun , Fendinger Nicholas J , Monteith Hugh D , Chandra Grish
Published: March 2010

The environmental fate ofoctamethylcyclotetrasiloxane(D4) and decamethylcyclopentasiloxane (D5) during municipal wastewater treatment has been investigated in an activated sludge pilot plant by continuously dosing the influent with exagerated amounts of the compounds and measuring their emissions in the off-gas, effluent, and sludge streams. The total removal was found to be 86.4 ± 3.9% for D4 and 95.8 ± 1.5% for D5 (±1 SD statistical uncertainty). However, low overall mass balances were found for both compounds in the pilot system. In order to elucidate the detailed removal mechanisms for these two compounds, the model TOXCHEM was used to simulate their removal and analyze their mass balances in the pilot system. Experimental and model results indicated that the low mass balances were caused by the significant underestimation of the primary sludge removal by the grab sampling method used for sludge analyses. This underestimation may be due to the high variability of the primary influent suspended solids concentration and hence inhomogeneity in the primary sludge underflow. When this underestimation was taken into account, primary sludge removal and volatilization in the aeration basin were found to contribute approximately equally to the removal of D4 and D5 in the pilot plant system. The present results are useful for the environmental risk assessment of these two siloxane compounds in the unlikely event of their point source discharge into municipal wastewater systems.
Reproductive success and biochemical effects in tree swallows (Tachycineta bicolor) exposed to chlorinated hydrocarbon contaminants in wetlands of the great lakes and st. lawrence river basin, USA and Canada
Authors: Bishop Christine A , Mahony Nancy A , Trudeau Suzanne , Pettit Karen E
Published: March 2010

Reproduction and biochemical indicators (vitamin A, ethoxyresorufin-O-deethylase [EROD], highly carboxylated porphyrins) of contaminant effects, and concentrations of organochlorine residues were measured in tree swallows from wetlands within the watersheds of the Great Lakes and the St. Lawrence River, USA and Canada. To assess the vitamin A sources in the tree swallow diets, insects were collected, by ligature, from nestlings at four of these sites. Diet samples were analyzed for retinol and α- and β-carotene. Marked differences were found in chlorinated hydrocarbon residues in eggs and nestlings among sites; however, we did not find any significant differences in hatching or fledging success. The maximum polychlorinated biphenyl (PCB) concentration found was 11.1 μg/g in eggs from Akwesasne Reserve, New York, USA, on the St. Lawrence River, whereas the highest p, p′-DDE concentration of 2.57 μg/g was found in eggs from Mud Creek, Ontario, Canada, in the Lake Erie watershed. Concentrations of other organochlorine pesticides and chlorobenzenes were low and not variable among sites. Significant differences in hepatic EROD activity, retinol and retinyl palmitate, and uroporphyrin in nestling birds existed among sites. Ethoxyresorufin O-deethylase activity was highest and retinol and retinyl palmitate were lowest at Cornwall Island, Ontario, Canada, in the St. Lawrence River, whereas porphyrins were highest at Toronto and Hamilton harbors, Ontario, Canada, in Lake Ontario. Ethoxyresorufin O-deethylase induction was significantly and negatively correlated with nestling hepatic retinol concentrations, whereas uroporphyrin concentrations were positively correlated with PCB congener 118 in nestlings. In contrast, few differences occurred in vitamin A concentrations in diet samples among sites. Together, these findings suggest that depressed hepatic vitamin A and elevated highly carboxylated porphyrin concentrations are strongly associated with sites with the highest organochlorine exposure in tree swallows.
Solid-phase genotoxicity assay for organic compounds in soil
Authors: Alexander Renee R , Chung Namhyun , Alexander Martin
Published: March 2010

A genotoxicity assay was developed for samples from environments in which toxic organic compounds are largely sorbed. The assay entails measurement of the rate of mutation of a strain of Pseudomonas putida to rifampicin resistance. The ratio of induced to spontaneous mutants was a function of the concentration of a test mutagen in soil. In studies of the utility of the assay in samples amended with 2-aminofluorene as a test mutagen, the ratio of induced to spontaneous mutants declined with time. The decline paralleled the disappearance of extractable 2-aminofluorene from the soil. The ratio of induced to spontaneous mutants also fell in four other soils with dissimilar properties. We suggest that this solid-phase assay is more appropriate for the estimation of genotoxicants sorbed in soil than assays involving extractants or suspensions of soil or sediment samples.
Effect of metal mixture (Cu, Zn, Pb, and Ni) on cadmium partitioning in littoral sediments and its accumulation by the freshwater macrophyte Eriocaùlon septangulàre
Authors: Stewart A Robin , Malley Diane F
Published: March 2010

The effect of a metal mixture (Cu, Zn, Pb, and Ni) on Cd fractionation in sediment and its accumulation by the freshwater macrophyte Eriocaùlon septangulàre was examined in an in situ experiment in the littoral zone at the Experimental Lakes Area, northwestern Ontario, Canada. Fresh sediment was spiked with Cd alone and together with the metal mixture at three concentration levels. Macrophytes were planted in the spiked sediment and placed at a water depth of 0.5 m. The distribution of Cd among sediment fractions (easily reducible [ER], reducible [R-ER], and organic [ORG]), pore water, and macrophytes was determined every 2 weeks for 10 weeks. Small differences among treatment levels in the recovery of Cd from the geochemical fractions were observed after 2 and 8 weeks but not after 10 weeks. At the highest concentration of the metal mixture, Cd repartitioned from the ER fraction onto the R-ER fraction after 2 weeks in situ. After 10 weeks, Cd was accumulated by the shoots (<2.6 μg/g dry weight) and roots (<45 μg/g dry weight) of E. septangulàre and had not reached steady state. Significantly higher Cd concentrations were found in the shoots of plants in the treatment with Cd alone and the treatment with the highest concentration of the metal mixture than in treatments with intermediate levels of the mixture. Partitioning of Cd among geochemical fractions in sediment alone did not explain differences in tissue Cd concentrations related to treatment level.
Heavy metals in Franklin's gull tissues: Age and tissue differences
Authors: Burger Joanna , Gochfeld Michael
Published: March 2010

We examined the concentrations of lead, cadmium, chromium, mercury, manganese, and selenium in feathers, liver, kidney, heart, brain, and breast muscle of Franklin's gulls (Larus pipixcan) nesting in northwestern Minnesota, USA, in 1994. Between 16% (chromium) and 71% (selenium, manganese) of the variation in metal concentrations was explained by tissue and age, except for selenium and arsenic, which were only explained by tissue. Of 35 possible differences (seven metals in five tissues), 24 significant age-related differences were found in Franklin's gulls, with young generally having lower concentrations of metals in all of their tissues than adults. A notable exception was the liver; young had significantly higher concentrations of selenium, chromium, manganese, and arsenic than did adults. Three notable findings were the following: young had significantly higher concentrations of selenium, chromium, manganese, and arsenic in their liver than did adults; young had 30 times as much chromium in the liver than adults; and adults had greatly elevated concentrations of cadmium in feathers, kidney, and liver.
Comparison of dissolved and total metals concentrations from acute tests with saltwater organisms
Authors: Lussier Suzanne M , Boothman Warren S , Poucher Sherry , Champlin Denise , Helmstetten Andrea
Published: March 2010

Aquatic life criteria (ALC) have traditionally been expressed for metals in terms of total-recoverable or acid-soluble concentrations. Recent U.S. Environmental Protection Agency policy recommended use of dissolved metal concentrations for setting water quality standards. Criteria derived from previous tests could be expressed in terms of dissolved metals if ratios of dissolvedto-total concentrations in those tests were consistent. Using those metals with insufficient dissolved metals data to directly derive criteria (arsenic (III), cadmium, chromium (VI), lead, nickel, selenium (IV), and zinc), we measured both total and dissolved metal concentrations in acute saltwater static and flow-through tests. Exposure conditions simulated those of original tests used to derive ALC. Partitioning of metals between dissolved and particulate forms was very consistent. Dissolved metal concentrations were greater than 90% of total concentrations in all tests, exceeding 95% in 10 of 13 tests. Dissolved-to-total metal ratios did not vary significantly with concentration, time, or type of test. Biological responses were consistent with historical data. Results implied that in acute saltwater toxicity tests used to establish ALC, metals were primarily dissolved. Thus criteria developed for metals based on total concentrations should be equally valid when expressed in terms of dissolved concentrations.
Differences in survival functions of mosquitofish (Gambusia affinis) and sand shiner (Notropis ludibundus) genotypes exposed to pesticides
Authors: Sullivan Karen Brown , Lydy Michael J
Published: March 2010

Differential genotypic tolerance of two species of fish native to the Great Plains of North America (the western mosquitofish [Gambusia affinis] and the sand shiner [Notropis ludibundus]) was examined in 96-h acute exposures to the pesticides lindane and parathion. Although a significant amount of data is available indicating that heavy metals cause selective genotypic mortality in aquatic organisms, very few studies have focused on the effects of pesticides on population genetic structure. Fish used in this experiment were captured from field populations in Kansas, USA, and acclimated to laboratory conditions for 1 month before the acute toxicity tests. Two hundred individuals of each species were exposed, in two separate experiments, to estimated LC70 concentrations of each pesticide for 96 h. Dead individuals were removed at 3-h intervals allowing for comparison of genotypic times-to-death. Individuals of each species were electrophoretically examined at two polymorphic loci. Phenotypes of mosquitofish were determined for phosphoglucose mutase (PGM) and malic enzyme (ME). Phenotypes of sand shiners were determined for PGM and aspartate aminotransferase (AAT). Three of eight statistical tests (two species × two loci × two pesticides) indicated significant differences among survival curves of genotypic classes. Genotypes of ME and PGM of mosquitofish exhibited significantly different survivorship functions in the parathion and lindane time-to-death tests, respectively. Genotypes of AAT of sand shiners exhibited significantly different survivorship curves when exposed to lindane. Given certain experimental limitations, these results support a continued examination of population genetic characteristics as biomarkers of environmental contamination.
Nuclear DNA content variation and double-strand DNA breakage in white-footed MICE (Peromyscus leucopus) collected from abandoned strip mines, Oklahoma, USA
Authors: Husby Michael P , McBee Karen
Published: March 2010

White-footed mice (Peromyscus leucopus) were collected during the spring, summer, and fall from four metal-polluted abandoned mines and three reference sites in eastern Oklahoma. Two mines in east-central (Okmulgee County) Oklahoma, USA, were matched with a nearby reference site, as were two mines in northeastern Oklahoma (Craig County). A third, remote reference site was located outside the Oklahoma coal belt in north-central Oklahoma (Payne County). Intercellular DNA content variation, measured as a coefficient of variation (CV) of nuclear DNA content among 20,000 cells per animal, was determined for splenocytes of individuals by flow cytometry. Double-strand breakage in liver DNA from the same animals was compared using agarose gel electrophoresis. Mice trapped from mines were expected to have more intercellular DNA content variation and more DNA breakage when compared with mice from the matched and remote reference sites. With one exception, mice from mine sites did not show any significant increase in nuclear DNA content variation during any season. Electrophoresis revealed that mice from both Okmulgee County mines had significantly more DNA breakage compared with the intracounty reference site in the spring. In the summer, mice from one Craig County mine had significantly higher levels of DNA breakage compared with the remote reference.
Model of biota-sediment accumulation factor for polycyclic aromatic hydrocarbons
Authors: Thomann Robert V , Komlos John
Published: March 2010

A model of the BSAF is constructed for PAHs using a steady-state representation of a benthic food web of a small creek. Analyses of the data collected by others on sediment, crayfish and sunfish PAH indicate that for the crayfish, the BSAF (kg org C kg lipid−1) range over log Kow is relatively narrow between 0.01 and 0.1. For the sunfish, a marked decline occurs in the station average BSAF with increasing log Kow to values ranging from 0.00001 to 0.005. A separation also occurs in the behavior of the PAH groups, with the unsubstituted PAHs constituting an approximate lower bound on the entire set of PAHs. Model calibration to crayfish and sunfish BSAF is accomplished through assignment of PAH (Kow) functions derived from laboratory data. The substituted naphthalenes in contrast to the unsubstituted PAHs are calculated to behave similarly to PCBs but lower by about one order of magnitude. Analyses of the model calibration indicate that (1) relative to the sunfish, the crayfish appear to exhibit reduced metabolism and higher gut assimilation efficiencies resulting in BSAFs different from sunfish BSAFs; (2) for the sunfish, the BSAF for unsubstituted PAHs declines rapidly with increasing Kow primarily because of low gut assimilation efficiency and increased metabolism and not because of reduced bioavailability of sediment PAH; and (3) the relative contribution of the food route and water route to the BSAF varies with Kow.
Quantitative structure-property relationships for the chemical reactivity of acrylates and methacrylates
Authors: Freidig Andreas P , Verhaar Henk J M , Hermens Joop L M
Published: March 2010

Reactivity towards three different nucleophiles was measured for a training set of six acrylates and seven methacrylates. The reactions studied were neutral and base-catalyzed hydrolysis and Michael addition of reduced glutathione (GSH). A linear free energy relationship (LFER) was established for the base-catalyzed hydrolysis rate constants of methacrylates, with the Taft parameter σ* as single descriptor. The GSH reactivity could be modeled with a partial least square regression (PLS) using four quantum chemical ground state parameters describing the difference in frontier orbital interaction and coulombic forces within the training set. Literature data for GSH reactivity was used to test the applicability of the PLS model. Differences in acute fish toxicity for structurally similar acrylates and methacrylates could be explained by their different potency as Michael-type acceptors.
Correlation between response of human cell line and distribution of sediment polycyclic aromatic hydrocarbons and polychlorinated biphenyls on Palos Verdes Shelf, California, USA
Authors: Anderson Jack W , Zeng Eddy Y , Jones Jennifer M
Published: March 2010

Sections of a sediment core collected from Station 7C near the County Sanitation Districts of Los Angeles County, California, USA, outfall were analyzed for total organic carbon (TOC), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). In addition, the biological responses to extracts from the same samples were determined using the P450 reporter gene system (RGS) assay. The profiles of TOC, PAHs, and PCBs were consistent in illustrating the predischarge baseline and the effects of improving wastewater treatment. Induction of the CYP1A1 gene using P450 RGS was correlated with total PAHs (r2 = 0.47) and better correlated with the B[a]P toxic equivalency quotients (r2 = 0.63) calculated using toxic equivalency factors (TEFs) derived from P450 RGS analyses of individual high molecular weight (4 to 6 rings) PAHs. Results from short (6 h) and long (16 h) exposures using the RGS assay suggested that a portion of the induction was from the slower acting chlorinated hydrocarbons (coplanar PCBs, dioxins, furans, etc.). Coplanar PCBs in the amounts of 0.9 to 3.1 μg/g were found in three core sections analyzed; hence, the induction of RGS was likely produced by both PAHs and coplanar PCBs. Since dioxins and furans were not analyzed, their contributions to the RGS responses are unknown. The RGS assay may be used to screen samples for potential toxicological importance before conducting costly chemical analyses.
Use of flow cytometry to detect genetic damage in mallards dosed with mutagens
Authors: Whittier Joanna B , McBee Karen
Published: March 2010

Data derived from mammalian, plant, and microbial models of genotoxicity may not be applicable to birds because of differences in avian genetic structure and physiology. The objective of this study was to develop a standardized, nonlethal genotoxicity assay for use with birds based on modification of a mammalian assay, flow cytometric measurement of variation in nuclear DNA content. Blood samples were collected from brachial veins of juvenile mallards (Anas platyrhynchos) before and after they were administered an oral dose of either methyl parathion (7.5, 15.0, or 30.0 mg/kg body weight), triethylenemelamine (0.25, 0.50, or 1.0 mg/kg body weight), or a solvent control. Cells were examined for nine parameters of DNA content and cell cycle kinetics. Results from blood samples were compared with results from spleen tissue, which is more commonly used in flow cytometric assays. Results were divided into three analysis groups: predose, postdose, and difference between pre- and postdose endpoints. Within triethylenemelamine dose groups, significant variation was found only in the predose postsynthetic gap (phase of cells after DNA synthesis; G2) to presynthetic gap (phase of cells before DNA synthesis; G1) ratio. Methyl parathion groups varied significantly in two parameters: postdose coefficient of variation of the G2 peak and postdose G2 to G1 ratio. Dose levels of positive control groups may have been too low to elicit a definite genotoxic response. Despite the limited response in the positive control, evidence of disturbance of normal cell cycle kinetics suggests flow cytometry is a viable alternative for genotoxicity analyses in birds.
Exploring the effects of consumer–resource dynamics on contaminant bioaccumulation by aquatic herbivores
Authors: Spencer Matthew , Fisher Nicholas S , Wang Wen-Xiong
Published: March 2010

We explore the consequences of consumer–resource interactions for bioaccumulation in two aquatic systems (cadmium accumulation in Dreissena polymorpha and polychlorinated biphenyl accumulation in calanoid copepods). We explicitly link the feeding and growth rates of consumers to the abundance of resources under a variety of assumptions about the nature of the interactions between them. The models are parameterized using field and laboratory data, and predictions are quantitatively compared with field-measured distributions of tissue concentrations. Different assumptions about consumer–resource interactions result in different predicted distributions of tissue concentrations and illustrate the way these interactions constrain the bioaccumulation of contaminants. Linking feeding and growth rates to resource abundances will be important whenever these abundances change over time. User-friendly software will make these ideas accessible to nontheoreticians.
Thermodynamic investigation of trichloroethylene adsorption in water-saturated microporous adsorbents
Authors: Farrell James , Hauck Benjamin , Jones Martin
Published: March 2010

Adsorption of trichloroethylene (TCE) in adsorbents containing hydrophilic and hydrophobic micropores was investigated in order to determine the mechanisms responsible for TCE adsorption on mineral solids. A high-pressure liquid chromatography method was used to measure TCE adsorption isotherms on three microporous adsorbents. Silica gel and zeolite type NaX were used as hydrophilic model adsorbents, and hexamethyldisilazane (HMDS)-treated silica gel was used as a model hydrophobic adsorbent. Batch uptake and desorption isotherms were also measured on the hydrophilic silica gel. Uptake of TCE by all three adsorbents was linear over the concentration range investigated. However, the silica gel desorption isotherm was highly nonlinear, as indicated by its Freundlich isotherm exponent of 0.58. Capillary phase separation into hydrophobic micropores was postulated as being responsible for the isotherm hysteresis. Supporting this hypothesis was the conformance of the TCE adsorption isotherm to Dubinin–Radushkevitch volume filling of micropores theory. The enthalpies for TCE adsorption on all three solids were determined by van't Hoff analysis of distribution coefficients measured over a temperature range from 5 to 90°C. The TCE adsorption enthalpies on the silica gel and HMDS silica gel were exothermic, but on the zeolite adsorption was endothermic. High exothermic adsorption enthalpies on the silica gel adsorbents indicated that TCE adsorption was occurring in hydrophobic micropores, and that adsorption on surfaces with large radii of curvature contributed only minimally to the total uptake. This indicates that the predominant mechanism for TCE adsorption on these mineral solids is not partitioning into the vicinal water layer.
Bioavailability and desorption characteristics of aged, nonextractable atrazine in soil
Authors: Johnson Stephanie E , Herman Janet S , Mills Aaron L , Hornberger George M
Published: March 2010

The bioavailability and desorption characteristics of nonextractable soil-aged atrazine were investigated to examine the significance of this potentially large contaminant fraction in agricultural soils. Radiolabeled atrazine-applied soil was aged for 3 months and then extracted by one of three methods—methanol-water (4: 1) at 75°C, acetone, and artificial soil water—representing a range of extraction efficiencies. Viable microcosms were constructed with the dried, extracted soil to compare rates and extents of microbially facilitated release and mineralization with desorption rates in sterile microcosms. The most rigorously extracted soil exhibited slow desorption over a 90-d period, but the other soil treatments showed continued slow sorption after reaching an initial maximum desorption concentration within 1 to 5 d. No microbially facilitated release of the nonextractable atrazine was detected for any of the treatments. Rates of ring-and chain-labeled atrazine mineralization declined with decreasing extractability of the soilassociated atrazine fraction. However, the extent of biodegradation (less than 2% of the total atrazine for all extracted soil treatments) was less than the extent of abiotic desorption. Mass-balance calculations suggest that all biodegradation occurred in the dissolved phase.
Biomonitoring of mercury pollution in a wetland near Ravenna, Italy by translocated bivalves (Mytilus galloprovincialis)
Authors: Cattani Otello , Fabbri Daniele , Salvati Marco , Trombini Claudio , Vassura Ivano
Published: March 2010

An active biomonitoring experiment using mussels (Mytilus galloprovincialis) was performed in Pialassa Baiona, a mercury-polluted coastal wetland near Ravenna, Italy. Three stations (A, B, and C) were selected along the south to north axis. Following a 52-d field exposure, organisms transplanted in the southernmost polluted area (station A) showed mean mercury concentration values of 660 ng/g (dry weight), 4.4 times the initial background level, and were still accumulating mercury. Mussels in both the central area (station B) and the northern area (station C) seemed to reach a steady state with mean mercury concentration values of 323 and 412 ng/g, respectively. This field experiment is the first study carried out in the Ravenna wetlands to evaluate mercury bioavailability in this environment. Finally, the efficiency of the population of Mytilus galloprovincialis selected for the field experiment as mercury bioaccumulators was tested in a laboratory experiment that revealed that up to 135 μg/g (dry weight) could be reached after 77 d of exposure to mercury-polluted water.
Concentration effects of 1,2-dichlorobenzene on soil microbiology
Authors: Thompson Ian P , Bailey Mark J , Boyd Elaine M , Maguire Nicola , Meharg Andrew A , Ellis Richard J
Published: March 2010

The effect of increasing concentrations (65, 130, 325, 1,300, and 3,250 μg/g soil dry weight) of 1,2-dichlorobenzene (1,2-DCB) on the microbial biomass, metabolic potential, and diversity of culturable bacteria was investigated using soil microcosms. All doses caused a significant (p < 0.05) decrease in viable hyphal fungal length. Bacteria were more tolerant, only direct total counts in soils exposed to 3,250 μg/g were significantly (p < 0.05) lower than untreated controls, and estimates of culturable bacteria showed no response. Pseudomonads counts were stimulated by 1,2-DCB concentrations of up to 325 μg/g; above this level counts were similar to controls. Fatty acid methyl ester analysis of taxonomic bacterial composition reflected the differential response of specific genera to increasing 1,2-DCB concentrations, especially the tolerance of Bacillus to the highest concentrations. The shifts in community composition were reflected in estimates of metabolic potential assessed by carbon assimilation (Biolog) ability. Significantly fewer (p < 0.05) carbon sources were utilized by communities exposed to 1,2-DCB concentrations greater than 130 μg/g (<64 carbon sources utilized) than control soils (83); the ability to assimilate individual carbohydrates sources was especially compromised. The results of this study demonstrate that community diversity and metabolic potential can be used as effective bioindicators of pollution stress and concentration effects.
Exposure of great egret (Ardea albus) nestlings to mercury through diet in the everglades ecosystem
Authors: Frederick Peter C , Spalding Marilyn G , Sepälveda Maria S , Williams Gary E , Nico Leo , Robins Robert
Published: March 2010

We estimated exposure of great egret (Ardea albus) nestlings to mercury in food in the Florida Everglades, USA, by collecting regurgitated food samples during the 1993 to 1996 breeding seasons and during 1995 measured concentrations of mercury in individual prey items from those samples. Great egret nestlings had a diet composed predominantly of fish (>95% of biomass), though the species composition of fish in the diet fluctuated considerably among years. Great egrets concentrated on the larger fish available in the marsh, especially members of the Centrarchidae. The importance of all nonnative fish fluctuated from 0 to 32% of the diet by biomass and was dominated by pike killifish (Belonesox belizanus) and cichlids (Cichlidae). Total mercury concentrations in prey fish ranged from 0.04 to 1.40 mg/kg wet weight, and we found a significant relationship between mass of individual fish and mercury concentration. We estimated the concentration of total mercury in the diet as a whole by weighting the mercury concentration in a given fish species by the proportion of that species in the diet. We estimate that total mercury concentrations in the diets ranged among years from 0.37 to 0.47 mg/kg fish (4-year mean = 0.41 mg/kg). We estimated total mercury exposure in great egret nestlings by combining these mercury concentrations with measurements of food intake rate, as measured over the course of the nestling period in both lab and field situations. We estimate that, at the 0.41 mg/kg level, nestlings would ingest 4.32 mg total mercury during an 80-day nestling period. Captive feeding studies reported elsewhere suggest that this level of exposure in the wild could be associated with reduced fledging mass, increased lethargy, decreased appetite, and, possibly, poor health and juvenile survival.
Linking insecticide contamination and population response in an agricultural stream
Authors: Liess Mathias , Schulz Ralf
Published: March 2010

The study aims to evaluate the impact of insecticides associated with rainfall-induced surface runoff from arable land on macroinvertebrate populations. These effects of insecticides were distinguished from the hydraulic stress also associated with surface runoff. Transient increase in discharge and insecticide contamination (maximum 6 μg/L parathion-ethyl in stream water, 302 μg/L fenvalerate in suspended particulates) was observed in a headwater stream subsequent to surface runoff from arable land. In the aquatic macroinvertebrate community, eight of the eleven abundant species disappeared, and the remaining three were reduced significantly in abundance following the insecticide-contaminated runoff. Recovery within 6 months was observed for four species and recovery within 11 months for nine species. Two species remained at a low population density for over a year. The effects of insecticides were distinguished from other parameters, such as hydraulic stress associated with surface runoff, as well. The causal connection between insecticide contamination and biological response was established by eliminating increased hydraulic stress during surface runoff using in-parallel bypass microcosms containing the dominant species Gammarus pulex and Limnephilus lunatus. The mortality of these species was similar to that of the same species in the stream. Additional microcosms, disconnected from the stream during runoff events, served as a control. Thus, the toxic potential of the runoff water is considered to be responsible for the observed effect on the macroinvertebrates. It is concluded that agricultural insecticide input may alter the dynamics of macroinvertebrate communities in streams.
Differences in neurobehavioral responses of chinook salmon (Oncorhynchus tshawytscha) and rainbow trout (Oncorhynchus mykiss) exposed to copper and cobalt: Behavioral avoidance
Authors: Hansen James A , Marr John C A , Lipton Joshua , Cacela Dave , Bergman Harold L
Published: March 2010

Behavioral avoidance of copper (Cu), cobalt (Co), and a Cu and Co mixture in soft water differed greatly between rainbow trout (Oncorhynchus mykiss) and chinook salmon (O. tshawytscha). Chinook salmon avoided at least 0.7 μg Cu/L, 24 μg Co/L, and the mixture of 1.0 μg Cu/L and 0.9 μg Co/L, whereas rainbow trout avoided at least 1.6 μg Cu/L, 180 μg Co/L, and the mixture of 2.6 μg Cu/L and 2.4 μg Co/L. Chinook salmon were also more sensitive to the toxic effects of Cu in that they failed to avoid ≤44 μg Cu/L, whereas rainbow trout failed to avoid ≤180 μg Cu/L. Furthermore, following acclimation to 2 μg Cu/L, rainbow trout avoided 4 μg Cu/L and preferred clean water, but chinook salmon failed to avoid any Cu concentrations and did not prefer clean water. The failure to avoid high concentrations of metals by both species suggests that the sensory mechanism responsible for avoidance responses was impaired. Exposure to Cu concentrations that were not avoided could result in lethality from prolonged Cu exposure or in impairment of sensory-dependent behaviors that are essential for survival and reproduction.
Chinook salmon (Oncorhynchus tshawytscha) and rainbow trout (Oncorhynchus mykiss) exposed to copper: Neurophysiological and histological effects on the olfactory system
Authors: Hansen James A , Rose James D , Jenkins Robert A , Gerow Kenneth G , Bergman Harold L
Published: March 2010

Olfactory epithelial structure and olfactory bulb neurophysiological responses were measured in chinook salmon and rainbow trout in response to 25 to 300 μg copper (Cu)/L. Using confocal laser scanning microscopy, the number of olfactory receptors was significantly reduced in chinook salmon exposed to ≥0 μg Cu/L and in rainbow trout exposed to ≥200 μg Cu/L for 1 h. The number of receptors was significantly reduced in both species following exposure to 25 μg Cu/L for 4 h. Transmission electron microscopy of olfactory epithelial tissue indicated that the loss of receptors was from cellular necrosis. Olfactory bulb electroencephalogram (EEG) responses to 10−3 M L-serine were initially reduced by all Cu concentrations but were virtually eliminated in chinook salmon exposed to ≥50 μg Cu/L and in rainbow trout exposed to ≥200 μg Cu/L within 1 h of exposure. Following Cu exposure, EEG response recovery rates were slower in fish exposed to higher Cu concentrations. The higher sensitivity of the chinook salmon olfactory system to Cu-induced histological damage and neurophysiological impairment parallels the relative species sensitivity observed in behavioral avoidance experiments. This difference in species sensitivity may reduce the survival and reproductive potential of chinook salmon compared with that of rainbow trout in Cu-contaminated waters.