bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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 &gt; 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

Abstract
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

AbstractSediment 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

AbstractSorption 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

Abstract
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

Abstract
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

Abstract
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

AbstractSunlight 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &lt; 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

AbstractWe 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

AbstractThe 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.