bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of atrazine and cyanazine on chlorpyrifos toxicity in Chironomus tentans (Diptera: Chironomidae)
Authors: Jin-Clark Ying , Lydy Michael J. , Zhu Kun Yan
Published: March 2010

Toxicities of two triazine herbicides (atrazine and cyanazine) and an organophosphate insecticide (chlorpyrifos) were evaluated individually and with each herbicide in binary combination with chlorpyrifos using fourth-instar larvae of the aquatic midge, Chironomus tentans. Chlorpyrifos at 0.25 μg/L resulted in an effect in less than 10% of midges in 48-h acute toxicity bioassays. Neither atrazine nor cyanazine alone at relatively high concentrations (up to 1,000 μg/L) caused significant acute toxicity to C. tentans. However, atrazine and cyanazine caused significant synergistic effects on the toxicity of chlorpyrifos when midges were exposed to mixtures of atrazine or cyanazine (10, 100, 1,000 μg/L) with chlorpyrifos (0.25 μg/L). At fixed concentrations (200 μg/L) of the herbicides, toxicity of chlorpyrifos was enhanced by 1.8- and 2.2-fold by atrazine and cyanazine, respectively, at the 50% effective concentration levels. Although atrazine and cyanazine are not effective inhibitors of acetylcholinesterase (AChE) in vitro, the synergism of the two triazine herbicides with chlorpyrifos was associated with increased in vivo inhibition of AChE in midges. We observed a positive correlation between the degree of inhibition of AChE and the concentration of atrazine or cyanazine in the presence of a fixed concentration of chlorpyrifos. It is possible that these herbicides may affect cytochrome P450 enzymes to confer synergistic effects on the toxicity of chlorpyrifos.
Evaluating and expressing the propagation of uncertainty in chemical fate and bioaccumulation models
Authors: MacLeod Matthew , Fraser Alison J. , Mackay Don
Published: March 2010

First-order analytical sensitivity and uncertainty analysis for environmental chemical fate models is described and applied to a regional contaminant fate model and a food web bioaccumulation model. By assuming linear relationships between inputs and outputs, independence, and log-normal distributions of input variables, a relationship between uncertainty in input parameters and uncertainty in output parameters can be derived, yielding results that are consistent with a Monte Carlo analysis with similar input assumptions. A graphical technique is devised for interpreting and communicating uncertainty propagation as a function of variance in input parameters and model sensitivity. The suggested approach is less calculationally intensive than Monte Carlo analysis and is appropriate for preliminary assessment of uncertainty when models are applied to generic environments or to large geographic areas or when detailed parameterization of input uncertainties is unwarranted or impossible. This approach is particularly useful as a starting point for identification of sensitive model inputs at the early stages of applying a generic contaminant fate model to a specific environmental scenario, as a tool to support refinements of the model and the uncertainty analysis for site-specific scenarios, or for examining defined end points. The analysis identifies those input parameters that contribute significantly to uncertainty in outputs, enabling attention to be focused on defining median values and more appropriate distributions to describe these variables.
Environmental fate and chemistry of raloxifene hydrochloride
Authors: Teeter Jerold Scott , Meyerhoff Roger D.
Published: March 2010

Raloxifene hydrochloride is a selective estrogen receptor modulator (SERM) used for the prevention and treatment of osteoporosis in women. Excretion of raloxifene occurs through the feces of patients. Raloxifene has the potential to be discharged into waste treatment systems after therapeutic use. Raloxifene hydrochloride was investigated using a battery of studies designed to describe its physical/chemical characteristics and define its fate in the environment. The mean measured solubility of raloxifene hydrochloride (± standard deviation) was 345.2 ± 15.6 μg/ml, 13.3 ± 0.6 μg/ml, 0.9224 ± 0.015 μg/ml, and 627.4 ± 132.0 μg/ml in aqueous buffers at pH 5, 7, and 9 and in unbuffered water, respectively. Raloxifene exhibited a mean molar absorptivity of 34,000 and a wavelength absorbance maximum at 287 nm for pH 5 and 7 aqueous buffer solutions and 297 nm at pH 9. Mean measured Km values were 516 ± 17, 1,323 ± 91, and 1,556 ± 135 at pH 5, 7, and 9, respectively. After 5 d at 50°C, raloxifene hydrolyzed 8.02, 10.61, and 23.81% in pH 5, 7, and 9 aqueous buffers, respectively. In a 28-d hydrolysis study at 25°C, the calculated first-order hydrolysis rates were 6.92 × 10−4, 1.70 × 10−3, and 7.66 × 10−3/d, and the corresponding half-lives were 1,001, 410, and 90 d in pH 5, 7, and 9 aqueous buffers, respectively. Raloxifene sorbed significantly to sewage treatment solids with Freundlich isotherm adsorption coefficients K between 2,000 and 3,000. Raloxifene degraded rapidly in the presence of sewage solids. In a system containing 0.470 g/L sludge solids, the raloxifene biodegradation rate and half-life were 0.0966/h and 7.17 h, respectively. In a 28-d aerobic—aquatic biodegradation study containing 30 mg/L sludge solids, the raloxifene biodegradation rate and half-life were 0.0188/d and 37 d, respectively. Given the fate and behavior of raloxifene in these studies, it is anticipated that raloxifene would rapidly dissipate in the environment.
Herring gulls and great black-backed gulls as indicators of contaminants in bald eagles in Lake Ontario, Canada
Authors: Weseloh D. Vaughn , Hughes Kimberly D. , Ewins Peter J. , Best Dave , Kubiak Timothy , Shieldcastle Mark C.
Published: March 2010

In 2000, a pair of bald eagles (Haliaeetus leucocephalus) nested successfully along the shorelines of Lake Ontario in North America for the first time since 1957. However, it is a continuing question whether bald eagles will be able to reproduce successfully as they return to nest on Lake Ontario. Great black-backed gulls (Larus marinus) and herring gulls (L. argentatus) were selected as surrogate species to predict contaminant levels in eggs of bald eagles nesting on Lake Ontario. Because of the suspected overlap in the diets of great black-backed gulls and bald eagles (i.e., fish, gull chicks, and waterfowl), the two species probably occupy a similar trophic level in the Lake Ontario food web and, thus, may have similar contaminant levels. Fresh great black-backed gull and herring gull eggs were collected from three study sites in eastern Lake Ontario in 1993 and 1994 and analyzed for contaminants. Average contaminant levels of dichlorodiphenyldichloroethane (p,p′-DDE), total polychlorinated biphenyls (PCBs), and dieldrin in great black-backed gull eggs were 12.85, 26.27, and 0.27 μg/g, respectively. The mean ratio of contaminant levels in great black-backed gull eggs to contaminant levels in herring gull eggs for these three contaminants was 2.09 (range of means, 1.73–2.38). Predicted levels of contaminants in bald eagle eggs in Lake Ontario would be expected to be similar to the mean levels reported for great black-backed gull eggs. As a comparison, contaminant levels in bald eagle eggs collected from other Great Lakes nesting sites were compared to mean levels reported for herring gull eggs collected from nearby sites in 1986 to 1995. The mean ratio of contaminant levels in bald eagle eggs to contaminant levels in herring gull eggs from these sites for DDE, total PCBs, and dieldrin was 2.40 (range of means, 1.73–3.28). These ratios are very similar to those reported using great black-backed gull eggs, illustrating the apparent similarity in trophic status shared by the two top predator species at these Great Lakes sites. Predicted levels of contaminants in bald eagle eggs at Lake Ontario are similar to levels reported for bald eagles breeding at other Great Lakes sites, suggesting that bald eagles may be able to breed on the shores of Lake Ontario. However, it is unclear at this time what level of breeding success should be expected, given that productivity at other similarly contaminated Great Lakes sites may be below that required to sustain a successful breeding population. The absence of an inland bald eagle population from which bald eagles may begin to colonize the shorelines of Lake Ontario may be delaying initiation of nesting site selection; other factors such as habitat and prey availability would likely not limit reproductive success.
Ecdysteroid synthesis and imaginal disc development in the midge Chironomus riparius as biomarkers for endocrine effects of tributyltin
Authors: Hahn Torsten , Schulz Ralf
Published: March 2010

Acute effects of the endocrine disruptor bis (tri-n-butyltin) oxide (TBTO) on molting-hormone biosynthesis and imaginaldisc development were investigated in larvae of the midge Chironomus riparius (Meigen). Ecdysteroid synthesis was measured by 24-h incubation of molting-hormone-synthesizing tissues (prothoracic glands) in vitro with or without the addition of TBTO. The amount of ecdysteroids produced was analyzed by radioimmunoassay. Developmental effects in vivo were investigated by determining the developmental phase of the genital imaginal discs before and after a 48-h exposure to TBTO in water. Sex-specific effects were found with both endpoints. Ecdysteroid synthesis was significantly reduced (analysis of variance [ANOVA], p ≤ 0.005) in female larvae at all concentrations (TBTO-Sn at 50, 500, and 5,000 ng/L), whereas a significant elevation of the biosynthesis rate occurred in male larvae in the 500-ng/L treatment (ANOVA, p ≤ 0.05). In vivo experiments with development of the genital imaginal disc within a 48-h exposure period revealed a significantly slower development in female larvae and a significantly faster development in male larvae (contingency tables, p ≤ 0.001) at all concentrations tested (TBTO-Sn at 10, 50, 200, and 1,000 ng/L). These results partly coincided with the in vitro effects on molting-hormone synthesis. The 48-h median lethal concentration (LC50) was 25 μg/L (20–30 μg/L 95% confidence intervals). The combination of in vitro and in vivo methods has proven to be a useful approach for the detection of endocrine effects of TBTO in C. riparius at levels 2,000-fold below the LC50 value. High sensitivity and short test duration suggest that chironomids may have potential as freshwater sentinel organisms for endocrine-disrupting chemicals.
Assessing the genotoxicity of chronic environmental irradiation by using mitochondrial dna heteroplasmy in the bank vole (Clethrionomys glareolus) at Chornobyl, Ukraine
Authors: Wickliffe Jeffrey K. , Chesser Ronald K. , Rodgers Brenda E. , Baker Robert J.
Published: March 2010

This study was designed to investigate whether or not chronic exposure to Chornobyl radiation poses a molecular genetic risk to mammals by examining a relatively rapidly evolving genetic system, mitochondrial DNA (mtDNA). More mtDNA mutations (-19%) and an increase in mtDNA heteroplasmy (-5%) occurred in the cytochrome b gene of an exposed mother-embryo set when compared to a relatively unexposed mother-embryo set. However, this increase was not statistically significant (p > 0.05). Our results, in conjunction with previous molecular genetic research on small mammals from Chornobyl, suggest that chronic exposure to environmental ionizing radiation does not increase the number of nucleotide substitutions, as predicted by studies using acute or subacute exposures. Thus, cumulative models of radiation risk would not appear to follow simple linear functions derived from high doses and dose rates. The equivocal nature of research regarding the effects of the Chornobyl accident indicates that future research is warranted such that models of chronic environmental exposure can be developed or refined. Although additional study is required to properly validate mtDNA heteroplasmy as a useful effect biomarker, examination of these data does not indicate that a significant risk to mtDNA exists in native rodents chronically exposed to both internal and external radiation.
Effect of sorption and desorption resistance on aerobic trichloroethylene biodegradation in soils
Authors: Lee Sangjin , Moe William M. , Valsaraj Kalliat T. , Pardue John H.
Published: March 2010

Biodegradation of trichloroethylene(TCE) by toluene-degrading bacteria was measured under aerobic conditions in aqueous and soil-slurry batch microcosms. For soil-phase experiments, a freshly contaminated soil and a soil containing only the desorption-resistant fraction of TCE were tested. In both cases, presence of soil resulted in biodegradation rates substantially lower than those determined in the absence of soil. In aqueous-phase experiments, an appreciable increase in the rate and extent of TCE biodegradation was observed in microcosms when toluene was added multiple times. The TCE degradation rates were clearly correlated with toluene dioxygenase (TOD) enzyme activity over time, thus providing an indication of the cometabolic pathway employed by the microbial population. In soil-slurry experiments containing freshly contaminated soil, a TCE degradation rate of approximately 150 μg TCE/kg/h was observed during the first 39-h period, and then the TCE degradation rate slowed considerably to 0.59 and 0.84 μg TCE/kg/h for microcosms receiving one and two additions of toluene, respectively. The TCE degradation rates in soil-slurry microcosms containing the desorption-resistant fraction of TCE-contaminated soil were approximately 0.27 and 0.32 μg TCE/kg/h in microcosms receiving one and two additions of toluene, respectively. It is clear from these results that mass transfer into the aqueous phase limited bioavailability of TCE in the contaminated soil.
Comparative in situ and laboratory sediment bioassays with juvenileMercenaria mercenaria
Authors: Ringwood Amy H. , Keppler Charles J.
Published: March 2010

Sediment toxicity assays were conducted with juvenile Mercenaria mercenaria to compare the results of laboratory assays and in situ deployments. Juvenile clams were deployed for one week at a variety of degraded and undegraded sites in Charleston Harbor, South Carolina, USA, during the summers of 1998, 1999, and 2000. Parallel laboratory assays were conducted with sediments collected from the deployment sites. Mortality and a sublethal endpoint, seed clam growth rate, were used to compare toxicity between reference and degraded sites. Growth rates of field-deployed clams tended to be higher than growth rates for laboratory assays, especially at the reference sites. Field studies indicated a higher potential for toxicity than did the laboratory studies at degraded sites. These studies suggest that laboratory assays may underestimate potential sediment toxicity at degraded sites. However, field growth rates may be affected by natural environmental factors (e.g., pH, dissolved oxygen, and salinity), so regression normalization techniques were used to distinguish the effects of these variables from those of contaminants.
Validation of a modified Flory-Huggins concept for description of hydrophobic organic compound sorption on dissolved humic substances
Authors: Georgi Anett , Kopinke Frank-Dieter
Published: March 2010

Sorption coefficients(KDOC) on dissolved organic matter (DOM) have been determined by means of solid-phase microextraction (SPME) for hydrophobic organic compounds (HOCs) of various classes, for example, polycyclic aromatic hydrocarbons (PAHs), noncondensed arenes, and alkanes. Relating the KDOC values obtained to the octanol-water partition coefficients of the solutes results in class-specific correlations. Obviously, PAHs have a higher affinity to DOM than other HOCs with equal KOW values. The different KDOC to KOW correlations can be combined into one general formula based on a modified Flory-Huggins concept. It permits the calculation of sorption coefficients from the solubility parameters (δ) and KOW values of the solutes and the solubility parameter of the sorbent. The latter value, which is specific to the DOM under consideration, can be determined from a single measured sorption coefficient. By applying the proposed Flory-Huggins concept, which is based on the presumption of nonspecific interactions between HOCs and DOM, the different affinities of PAHs, noncondensed arenes, and alkanes to DOM can be accurately predicted.
Sorption kinetics of selected volatile organic compounds in humin
Authors: Shih Yang-Hsin , Wu Shian-Chee
Published: March 2010

Each component of the chemically heterogeneous soil exhibits a unique sorption behavior toward organic sorbates. The sorption kinetics of some volatile organic compounds (VOCs) in pressed humin disks was investigated by tracking the weight change of the disks with a microbalance. Higher sorbing capacity for more polar VOCs as well as C13 nuclear magnetic resonance data indicates that humin was more hydrophilic than Aldrich humic acid (Milwaukee, WI, USA). The apparent diffusivity of acetone, toluene, and hexane in the disks ranged from 10−8 to 10−10 cm2/s. The sorbed toluene in humin does not seem persistent to desorption; however, acetone and hexane, either as polar or linear compounds in humin, show persistence against desorption. On completion of the desorption experiments, there were approximately 35 and 20% sorbate residue for acetone and hexane, respectively.
Development and application of an oil toxicity and exposure model, OilToxEx
Authors: French-McCay Deborah P.
Published: March 2010

An oil toxicity and exposure model (OilToxEx) was developed and validated for estimation of impacts to aquatic organisms resulting from acute exposure to spilled oil. Because oil exposure is shorter than the time required for equilibrium between the organism and the water to be reached, the time and temperature dependence of toxicity is addressed. Oil toxicity is a function of aromatic composition and the toxicity of individual aromatics in the mixture. Lethal concentration to 50% of exposed organisms (LC50), as a function of octanol-water partition coefficient (Kow), and an additive model are used to estimate the toxicity of monoaromatic and polycyclic aromatic hydrocarbon mixtures in water-soluble fractions (WSF) and oil-in-water dispersions (OWD) of oil. The toxicity model was verified by comparison with oil bioassay data where the exposure concentrations of aromatics were measured. The observed toxicity in the bioassays could be accounted for by the additive narcotic effects of the dissolved aromatics in the exposure media. Predicted LC50s were compared to those calculated from measured concentrations after spills to verify the exposure model for field conditions. These results indicate that the additive toxicity and exposure model may be used to estimate toxicity of untested oils and spill conditions.
Minimum cross-sectional diameter: Calculating when molecules may not fit through a biological membrane
Authors: Cash Gordon G. , Nabholz J. Vincent
Published: March 2010

Some compounds that are predicted to be toxic to aquatic organisms instead show no toxicity. In some cases, this phenomenon occurs because the molecules are too large physically to pass through biological membranes, at least by passive transport. The size of the smallest circle through which a molecule can pass is called its minimum effective cross-sectional diameter. Until now, no method has been generally available for determining this parameter. Here, we present such a method, based on vector analysis, that produces results in seconds or minutes, even for relatively large molecules, on a desktop computer. The only input required is the Cartesian coordinates and van der Waals radii of the constituent atoms. The gas-phase, energy-minimized structure is used as an approximation, because to our knowledge, no practical means of experimentally measuring an effective diameter in solution is currently available.
Quantitative structure-activity relationship for the photoinduced toxicity of polycyclic aromatic hydrocarbons to the luminescent bacteriaVibrio fischeri
Authors: El-Alawi Yousef S. , Huang Xiao-Dong , Dixon D. George , Greenberg Bruce M.
Published: March 2010

Sunlight can greatly enhance the toxicity of polycyclic aromatic hydrocarbons (PAHs). Photosensitization reactions (e.g., generation of singlet-state oxygen) and photomodification reactions (e.g., photooxidation of PAHs to more toxic species) are both pathways of photoinduced toxicity of PAHs. Previously, a quantitative structure-activity relationship (QSAR) was developed for PAHs showing that a photosensitization factor (PSF) and photomodification factor (PMF) can be additively combined to describe photoinduced toxicity. That QSAR model was developed for the photoinduced toxicity of 16 PAHs to the higher plant Lemna gibba. The objective of this study was to apply the QSAR model developed for L. gibba to another organism. The organism chosen was the luminescent marine bacteria Vibrio fischeri. Toxicity data used for the QSAR model were inhibition of luminescence and inhibition of growth of V. fischeri. Both short-term (15 min) and long-term (18 h) assays of toxicity were used. Light did not impact on PAH toxicity in the short-term assay, and thus the QSAR model did not correlate well with these data. Conversely, light greatly enhanced toxicity when the long-term assay was employed. The PMFs for the PAHs from the L. gibba QSAR showed a moderate correlation to bacterial toxicity in the long-term assay, whereas the PSFs showed only a weak correlation to toxicity. As was the case for L. gibba, summing the PMF and the PSF resulted in a strong correlation to toxicity that had predictive value. Thus, a QSAR model derived for plants accurately described the toxicity of PAHs to a bacterial species. This indicates that the bipartite mechanism of PAH-photoinduced toxicity may be applicable to other organisms.
Application of the dual-mode model for predicting competitive sorption equilibria and rates of polycyclic aromatic hydrocarbons in estuarine sediment suspensions
Authors: Zhao Dongye , Hunter Margaret , Pignatello Joseph J. , White Jason C.
Published: March 2010

We investigated competitive sorption and desorption of phenanthrene, anthracene, and pyrene added to an estuarine sediment from Guilford (CT, USA) on Long Island Sound. The reduction in the equilibrium uptake of a primary solute in the presence of one or both cosolutes was well predicted over the entire isotherm by the dual-mode model, which postulates dissolution and hole-filling domains in sediment organic matter. Isotherms obtained in binary or ternary solute systems were suppressed, and the shapes were more linear than the corresponding single-solute isotherms. In the limit of infinite dilution of the single solute, sorption in the hole-filling domain is a factor of 1.4 to 1.9 times more favorable than sorption in the dissolution domain. A competitive dual-mode radial diffusion model was applied to the batch uptake and sequential-batch desorption rate data. The model captures the uptake and release curves well. The competitive effect slightly accelerates sorption, as predicted. The competitive effect accelerates desorption, but from the existing data it was not possible to decide how much was due to favorable thermodynamic versus favorable kinetic effects. The concentration-independent diffusion rate parameter corresponding to the dissolution domain was approximately the same for sorption and desorption (0.02/h), and little or no sorption hysteresis was observed.
Modeling polychlorinated biphenyl congener patterns and dechlorination in dated sediments from the Ashtabula River, Ohio, USA
Authors: Imamoglu Ipek , Li Kai , Christensen Erik R.
Published: March 2010

Polychlorinated biphenyl (PCB) congeners were analyzed in four deep, dated sediment cores from the Ashtabula River (OH, USA), for the purpose of identifying relevant PCB sources and congener patterns. The time span for three of the cores is from the mid 1960s to 1998, whereas the fourth has a time span of six years. The total PCB concentrations are in the range of 0.4 to 6.8 μg/g dry weight, with the highest concentrations observed in samples from the 1970s. A factor analysis (FA) model with nonnegative constraints was used to investigate the sources and patterns of PCBs. Additionally, a new model, based on a least squares method, was developed to identify possible patterns of anaerobic dechlorination of PCBs in the sediments, and to quantify the relevant dechlorination pathways. Both models were validated successfully either by artificially created data sets (FA model) or by using laboratory data from the literature (dechlorination model). The FA model revealed two significant sources. The first was identified as a slightly altered Aroclor 1248. The second did not resemble any Aroclor closely, but was very similar to the overall average congener profile of all samples. Simulation of anaerobic dechlorination on an Aroclor 1248 profile from the literature, according to dechlorination activities H/H′, as defined in the literature, yielded a congener profile very similar to that of the second pattern. This indicates the likelihood of anaerobic dechlorination of PCBs in Ashtabula River sediments.
Use of triolein-semipermeable membrane devices to assess the bioconcentration and sediment sorption of hydrophobic organic contaminants in the Huaihe River, China
Authors: Wang Zijian , Wang Yi , Ma Mei , Lu Yibing , Huckins James
Published: March 2010

Triolein-containing semipermeable membrane devices (triolein-SPMD) were deployed 1 m above the sediments at two sampling sites in the Huaihe River, China, for a period of 28 d. Sediment and fish samples were simultaneously collected from the same sampling sites. Concentrations of substituted benzenes, selected pesticides, polycyclic aromatic hydrocarbon (PAH), and polychlorinated biphenyls (PCBs) were measured in triolein-SPMDs, sediments, and fishes. The concentrations of these hydrophobic organic contaminants (HOCs) in fish and in sediment organic carbon were correlated with HOCs accumulation in triolein-SPMDs. Our results showed reasonably good correlations between the log concentrations of contaminants in fish lipid and in triolein-SPMDs. Good correlations were also found between the log concentrations of contaminants in sediment organic carbon and in triolein- SPMDs (except for PAHs). The results were discussed in terms of the partitioning of hydrophobic organic contaminants among different compartments in the aquatic environment and the suitability of using triolein-SPMDs to predict bioconcentration factor (BCF) and sediment-water partitioning coefficient (Koc).
Mouthpart deformities and community composition of chironomidae (diptera) larvae downstream of metal mines in New Brunswick, Canada
Authors: Swansburg Erin O. , Fairchild Wayne L. , Fryer Brian J. , Ciborowski Jan J. H.
Published: March 2010

The effect of metal enrichment on chironomid communities was examined in streams receiving mine drainage from metal mining operations in New Brunswick, Canada. At five sites receiving mine drainage, metal concentrations were significantly (p < 0.05) elevated in water (Zn), periphyton (Cd, Co, Cu, and Zn), and chironomid tissue (Cu, Cd, and Zn) relative to five paired reference locations. Metal concentrations in chironomid larvae were significantly correlated with concentrations in both water and periphyton. Chironomid communities were severely affected at sites receiving mine drainage as demonstrated by reduced genera richness and altered community composition. Sites receiving mine drainage exhibited an increased abundance of metal-tolerant Orthocladiinae and a reduced abundance of metal-sensitive Tanytarsini relative to reference sites. The incidence of mentum deformities was significantly elevated at sites receiving mine drainage (1.43 ± 0.24%), with the mean percentage approaching a doubling of that observed at reference sites (0.79 ± 0.22%). Trace metal concentrations at mine-associated streams in New Brunswick significantly affected the benthic community and have the potential to alter the structure and function of these aquatic ecosystems.
Genetic and physiological responses of flounder (Platichthys flesus) populations to chemical contamination in estuaries
Authors: Laroche Jean , Quiniou Louis , Juhel Guillaume , Auffret Michel , Moraga Dario
Published: March 2010

We sampled and analyzed European flounder (Platichthys flesus) from two highly contaminated estuaries (Seine and Loire, France) and one moderately contaminated estuary (reference site: Ster, France). Significant and convergent modifications of the allelic frequencies for the loci phosphoglucomutase (PGM), glucose phosphate isomerase 2 (GPI-2), mannose phosphate isomerase (MPI), and aspartate aminotransferase (AAT-2) were evident for fish in the contaminated sites versus fish from the reference site. Back-calculation from otoliths showed that the average growth rate of fish between the first and the second winter was greater at the reference site (≈150 mm/year) than at the contaminated sites (≈100 mm/year). Flounder from the reference site also had a higher condition factor (somatic wt/(fish length)3) compared to fish from the two contaminated sites. However, the observed pattern of growth rate and condition factor might be biased by particular environmental conditions other than contaminants and must be confirmed by more extensive study. Flow cytometry analysis of fish blood revealed a significant difference in the frequency of abnormal profiles for fish from the Seine (20%) versus from the Ster (3%). We interpret this result as a marked genotoxic effect of contaminants on fish in the Seine system. Some genotypes, such as PGM 85/85, appeared to be linked to the measured components of fitness, particularly to DNA integrity. Thus, these genotypes might be considered to be more tolerant to pollutants. The frequency of the PGM 85 allele was clearly elevated in flounder from the more contaminated sites, compared to flounder from the reference site.
Multilevel effects of sublethal fenitrothion exposure inChironomus ripariusMg. (Diptera, Chironomidae) larvae
Authors: Choi Jinhee , Caquet Thierry , Roche HéLène
Published: March 2010

The effects of fenitrothion exposure on fourth-instar Chironomus riparius larvae were investigated on biochemical, physiological, and population-level parameters. Biochemical effects were investigated through measurements of acetylcholinesterase and cytosolic superoxide dismutase activities. Water content and dry weight of the larvae were used as physiological parameters, and the emergence rate of adults was used as a descriptor of population-level effects. Results showed that the response of most parameters exhibited a concentration-dependent relationship. Although biochemical parameters proved to be very sensitive, no direct relation was observed with effects at a higher level of biological organization. Perturbations of osmoregulation, as reflected by changes in water content of the larvae, were more directly related with emergence failure. This study demonstrates that the use of several biological parameters can provide complementary information about the effects of chemical exposure. Therefore, use of a multilevel approach in C. riparius seems to be a promising way to diagnose environmental quality.
Controlled release experiments with nonylphenol in aquatic microcosms
Authors: Pfister Gerd , Jüttner Ingrid , Severin Gabriele F. , Schramm Karl-Werner , Kettrup Antonius
Published: March 2010

A method of controlled release of technical nonylphenol (tNP) was developed to simulate realistic exposure in ecotoxicological studies on aquatic organisms. The direct addition of tNP from an aqueous stock solution into 50 ml of water led to a concentration decrease of 80 to 90% weight/volume (w/v) from nominal values within 48 h. The inclusion of tNP in semipermeable low-density polyethylene (LDPE) lay-flat tubing (controlled-release devices [CRDs]) of different length allowed a continuous release into pure water at a rate of about 30 μg/cm2/d. Using CRDs in aquaria containing 15 L of 63-μm-filtered lake water, eight different concentrations with maxima between 38.1 and 326.7 μg/L were maintained for 11 d. During a second experiment in 15-L aquaria, five replicates of three concentrations were maintained using CRDs of the same length. Concentrations after 38 d varied between 0.1 and 6.7, 26.1 and 41.9, and 49.9 and 76.0 μg/L. In aquatic microcosms containing 230 L of lake water, a natural plankton community, 50 L of sediment, and macrophytes, seven different tNP concentrations (maxima 11–120.1 μg/L) were maintained over 45 d using CRDs of different length. They were replaced after 14 and 25 d because release of tNP was slower than predicted from laboratory experiments. Concentrations in the top 1-cm sediment layer were on average 19 times higher during the dosing period than concentrations in the water at the same time. In the sediments, different levels of applications led to concentrations that differed less distinctly than in the water. This method is suitable for exposing aquatic organisms continuously to constant, ecologically relevant concentrations of NP and represents an improvement over previous dosing methods in which exposure varied.
Predicted and measured levels of azinphosmethyl in the Lourens River, South Africa: Comparison of runoff and spray drift
Authors: Dabrowski James M. , Schulz Ralf
Published: March 2010

Runoff and spray drift are important sources of nonpoint pesticide pollution in surface waters, but few studies have directly compared these routes of input in an exposure assessment scenario. To this end, a runoff formula suggested by the Organization for Economic and Cooperative Development (Paris, France) and basic drift values (95th percentiles) were integrated into a geographical information system (GIS) to predict runoff and spray drift-related loading of azinphosmethyl (AZP) in the Lourens River (LR), South Africa. The GIS-integrated calculations were first validated in the tributaries of the river, where measured loads were well predicted for both runoff (r2 = 0.95; p < 0.0001; n = 9) and spray drift (r2 = 0.96; p = 0.0006; n = 8). Through extrapolation to the catchment scale containing 400 ha of orchards, the GIS-integrated calculations predicted similar loads of AZP as measured in the Lourens River mainstream for six runoff (between a factor of 1.03 and 1.86 lower) and six spray drift (between a factor of 1.1 and 2.4 higher) events. Mean measured loads per event were significantly (p = 0.004) higher for runoff (27.8 ± 19.1 g) than for spray drift (0.69 ± 0.32 g). Based on long-term meteorological data and average application regimes, runoff leads to a higher annual load (47.6 g) than spray drift (5.5 g) in the Lourens River. Runoff is clearly a more important source of nonpoint pollution in the studied catchment, and mitigation strategies should focus first on addressing this aspect on a catchment scale and second on addressing problem areas on a subcatchment scale.
Biodegradation during contaminant transport in porous media: 6. Impact of sorption on coupled degradation-transport behavior
Authors: Famisan Gale B. , Brusseau Mark L.
Published: March 2010

Bioavailability is one of the critical factors influencing the biodegradation and bioremediation of organic compounds. The bioavailability of many organic contaminants is controlled in part by the nature, magnitude, and rate of sorption/desorption processes. This study investigates the impact of sorption and associated retardation on the bioavailability and biodegradation of aromatic hydrocarbons during transport in porous media. Miscible-displacement experiments were conducted using naphthalene and 2-naphthol as the model sorbing compounds and salicylate, a degradation product of naphthalene, as a nonsorbing reference compound. Two porous media were used, one (Eustis soil, FL, USA) with moderate sorption capacity and one (quartz sand) with no measurable sorption of the compounds. The porous media were sterilized and inoculated with Pseudomonas putida RB1353, an organism that degrades naphthalene and its derivatives. The biodegradation and transport of all three substrates in quartz sand were significantly influenced by microbial lag, the effects of which were observed within two to three pore volumes (3–4.5 h). This was also true for salicylate transport in the Eustis soil system. Conversely, biodegradation lag effects were not observed for naphthalene or 2-naphthol in the Eustis soil system. In addition, the masses of naphthalene and 2-naphthol degraded were significantly greater for the Eustis soil system compared to the quartz sand system. As noted previously, naphthalene and 2-naphthol were sorbed by the Eustis soil but not the quartz sand, while salicylate was not sorbed by either media. These results indicate that the increased residence time associated with sorption of naphthalene and 2-naphthol by Eustis soil enhanced overall biodegradation and obviated the impact of lag on observed transport behavior.
Biotransformation of 3,5-dibromo-4-hydroxybenzonitrile under denitrifying, Fe(III)-reducing, sulfidogenic, and methanogenic conditions
Authors: Knight Victoria K. , Berman Mitchell H. , Häggblom Max M.
Published: March 2010

Bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) is a halogenated aromatic nitrile herbicide used on a variety of crops for the postemergence control of annual broad-leaved weeds. The anaerobic biodegradability of bromoxynil and its aerobic transformation product, 3,5-dibromo-4-hydroxybenzoate, were examined in enrichment cultures established with anaerobic sediment under denitrifying, Fe(III)-reducing, sulfidogenic, and methanogenic conditions. Bromoxynil (100 μM) was depleted in 20 to 30 d in the methanogenic, sulfidogenic, and Fe(III)-reducing enrichments but was stable under denitrifying conditions. The 3,5-dibromo-4-hydroxybenzoate (100 μM) was depleted within 20 to 35 d under all four anaerobic conditions. Both compounds were stable in sterile controls. Bromoxynil and 3,5-dibromo-4-hydroxybenzoate were readily utilized upon respiking of the cultures. During utilization of bromoxynil, stoichiometric release of bromide was observed with transient accumulation of metabolites identified as bromocyanophenol, cyanophenol, and phenol. Bromoxynil heptanoate and octanoate were rapidly hydrolyzed to bromoxynil, which was further degraded. These results indicate that bromoxynil and 3,5-dibromo-4-hydroxybenzoate are degraded under different anaerobic conditions. Anaerobic degradation of bromoxynil proceeds via reductive debromination to 4-cyanophenol, which is further transformed to phenol and can ultimately be degraded to carbon dioxide.
Bioaugmentation of tar-contaminated soils under field conditions using Pleurotus ostreatus refuse from commercial mushroom production
Authors: Hestbjerg Helle , Willumsen Pia Arentsen , Christensen Mette , Andersen Ole , Jacobsen Carsten Suhr
Published: March 2010

The influence of the white rot fungus Pleurotus ostreatus on the degradation of selected poly- and heterocyclic aromatic hydrocarbons (referred to as polycyclic aromatic hydrocarbons [PAHs]) in soil was investigated under field conditions representing the Northern temperate zone. Pleurotus ostreatus was added to two contaminated soils in the form of homogenized refuse from the commercial production of fungus. The soils were collected from a former shipyard (the B&W soil) and underneath a former coal tar storage at an old asphalt factory in Denmark (the Ringe soil). Treatments (control, soil mixed with autoclaved sawdust medium, and soil mixed with P. ostreatus refuse) were set up in triplicate in concrete cylinders (height, 50 cm; diameter, 60 cm). The activity of P. ostreatus was measured as laccase activity and phenanthrene (PHE)- and pyrene (PYR)-degrading bacteria were enumerated. Twenty-one different PAHs were quantified. After nine weeks the concentrations of the 3-, 4-, 5-, and 6-ring PAHs in the Ringe soil were reduced by 78, 41, and 4%, respectively. These reductions corresponded with high initial laccase activity, a decrease in pH caused by the fungus, and an increase in the number of PHE- and PYR-degrading bacteria. No significant PAH degradation was observed in the B&W soil. Reasons for the difference in performance of P. ostreatus in the two soils are discussed in terms of soil histories and bioavailability. The use of P. ostreatus refuse holds promising potential for bioremediation purposes.
A new tool for laboratory studies on volatilization: Extension of applicability of the photovolatility chamber
Authors: Wolters Andre , Kromer Thomas , Linnemann Volker , Schäffer Andreas , Vereecken Harry
Published: March 2010

Volatilization from soil and plant surfaces after application is an important source of pesticide residues to the atmosphere. The laboratory photovolatility chamber allows the simultaneous measurement of volatilization and photodegradation of 14C-labeled pesticides under controlled climatic conditions. Both continuous air sampling, which quantifies volatile organic compounds and 14CO2 separately, and the detection of surface-located residues allow for a mass balance of radioactivity. The setup of the photo-volatility chamber was optimized, and additional sensors were installed to characterize the influence of soil moisture, soil temperature, and evaporation on volatilization. The modified flow profile in the glass dome of the chamber arising from the use of a highperformance metal bellows pump was measured. Diminished air velocity near the soil surface and a wind velocity of 0.2 m/s in 3 cm height allowed the requirements of the German guideline on assessing pesticide volatilization for registration purposes to be fulfilled. Determination of soil moisture profiles of the upper soil layer illustrated that defined water content in the soil up to a depth of 4 cm could be achieved by water saturation of air. Cumulative volatilization of [phenyl-UL-14C]parathion-methyl ranged from 2.4% under dry conditions to 32.9% under moist conditions and revealed the clear dependence of volatilization on the water content in the top layer.
Predicting ready biodegradability of premanufacture notice chemicals
Authors: Boethling Robert S. , Lynch David G. , Thom Gary C.
Published: March 2010

Chemical substances other than pesticides, drugs, and food additives are regulated by the U.S. Environmental Protection Agency (U.S. EPA) under the Toxic Substances Control Act (TSCA), but the United States does not require that new substances be tested automatically for such critical properties as biodegradability. The resulting lack of submitted data has fostered the development of estimation methods, and the BioWIN models for predicting biodegradability from chemical structure have played a prominent role in premanufacture notice (PMN) review. Until now, validation efforts have used only the Japanese Ministry of International Trade and Industry (MITI) test data and have not included all models. To assess BioWIN performance with PMN substances, we assembled a database of PMNs for which ready biodegradation data had been submitted over the period 1995 through 2001. The 305 PMN structures are highly varied and pose major challenges to chemical property estimation. Despite the variability of ready biodegradation tests, the use of at least six different test methods, and widely varying quality of submitted data, accuracy of four of six BioWIN models (MITI linear, MITI nonlinear, survey ultimate, survey primary) was in the 80+% range for predicting ready biodegradability. Greater accuracy (>90%) can be achieved by using model estimates only when the four models agree (true for 3/4 of the PMNs). The BioWIN linear and nonlinear probability models did not perform as well even when classification criteria were optimized. The results suggest that the MITI and survey BioWIN models are suitable for use in screening-level applications.
Inverse relationship between bioconcentration factor and exposure concentration for metals: Implications for hazard assessment of metals in the aquatic environment
Authors: McGeer James C. , Brix Kevin V. , Skeaff James M. , DeForest David K. , Brigham Sarah I. , Adams William J. , Green Andrew
Published: March 2010

The bioconcentration factor (BCF) and bioaccumulation factor (BAF) are used as the criteria for bioaccumulation in the context of identifying and classifying substances that are hazardous to the aquatic environment. The BCF/BAF criteria, while developed as surrogates for chronic toxicity and/or biomagnification of anthropogenic organic substances, are applied to all substances including metals. This work examines the theoretical and experimental basis for the use of BCF/BAF in the hazard assessment of Zn, Cd, Cu, Pb, Ni, and Ag. As well, BCF/BAFs for Hg (methyl and inorganic forms) and hexachlorobenzene (HCB) were evaluated. The BCF/BAF data for Zn, Cd, Cu, Pb, Ni, and Ag were characterized by extreme variability in mean BCF/BAF values and a clear inverse relationship between BCF/BAF and aqueous exposure. The high variability persisted when even when data were limited to an exposure range where chronic toxicity would be expected. Mean BCF/BAF values for Hg were also variable, but the inverse relationship was equivocal, in contrast with HCB, which conformed to the BCF model. This study illustrates that the BCF/BAF criteria, as currently applied, are inappropriate for the hazard identification and classification of metals. Furthermore, using BCF and BAF data leads to conclusions that are inconsistent with the toxicological data, as values are highest (indicating hazard) at low exposure concentrations and are lowest (indicating no hazard) at high exposure concentrations, where impacts are likely. Bioconcentration and bioaccumulation factors do not distinguish between essential mineral nutrient, normal background metal bioaccumulation, the adaptive capabilities of animals to vary uptake and elimination within the spectrum of exposure regimes, nor the specific ability to sequester, detoxify, and store internalized metal from metal uptake that results in adverse effect. An alternative to BCF, the accumulation factor (ACF), for metals was assessed and, while providing an improvement, it did not provide a complete solution. A bioaccumulation criterion for the hazard identification of metals is required, and work directed at linking chronic toxicity and bioaccumulation may provide some solutions.
Dehydrochlorination of 1,1,1-trichloroethane and pentachloroethane by microbially reduced ferruginous smectite
Authors: Cervini-Silva Javiera , Kostka Joel E. , Larson Richard A. , Stucki Joseph W. , Wu Jun
Published: March 2010

Reduction of structural Fe(III) in smectite clay minerals has been identified as a means to promote dechlorination of polychlorinated ethanes, but its environmental significance has yet to be fully assessed because Fe reduction has normally been achieved by agents uncommon in the environment (e.g., dithionite). This study reports the dehydrochlorination of pentachloroethane and 1,1,1-trichloroethane in the presence of ferruginous smectite reduced by two cultures of microorganisms, Shewanella oneidensis strain MR-1 (MR-R) and an enrichment culture from rice paddy soils (PS-R), in aqueous suspension under anoxic conditions. Microbially reduced ferruginous smectite facilitated dehydrochlorination of 1,1,1-trichloroethane to 1,1-dichloroethene with up to 60% conversion within 3 h of incubation time. In contrast, no formation of 1,1-dichloroethene was observed after incubation of 1,1,1-trichloroethane with chemically reduced ferruginous smectite for 24 h. Microbially reduced ferruginous smectite by MR-R and PS-R promoted the dehydrochlorination of pentachloroethane to tetrachloroethene by 80 and 15%, respectively, after 3 h of incubation time. The conversion of pentachloroethane to tetrachloroethene in the presence of chemically reduced ferruginous smectite after 24 h was 65%. These results indicate that structural Fe(II) in clay minerals has the potential to be an important reductant controlling the fate of organic chemicals in contaminated sediments.