bluuebunny/crossref_metadata_2025_split huggingface dataset:
Empirical assessment of an ambient toxicity risk ranking model's ability to differentiate clean and contaminated sites
Authors: Hartwell S Ian 
Published: March 2010

Abstract
Ambient toxicity results were used to investigate statistical implications of sampling design options for an existing toxicological risk ranking model. A battery of water column and sediment toxicity bioassays measuring lethal and sublethal endpoints was employed with fish, invertebrates, vascular plants, and bacteria. Bioassays were conducted monthly from July through September 1995 with water from three stations in the South River estuary, Maryland, USA, and a reference station. Sediment bioassays were conducted in August with five discrete samples taken from each station. Water column assays indicated low-level contamination at the upstream stations. Sediment bioassays yielded greater toxic responses than water column assays. The toxicological risk ranking model identified a strong toxicity gradient from upstream to downstream in the South River. Toxicological risk scores for the downstream station in the South River were comparable to the reference station. Statistical analyses demonstrated that the risk ranking model does not require field sample replication for tributary-wide assessment. Characterization of an entire estuary does require broad coverage to assess the system as a whole, however. Threshold levels of toxic impact can be quantified with the model.
Minimum data required for deriving soil quality criteria from invertebrate ecotoxicity experiments
Authors: Vega Milagrosa M , Urzelai Arantzazu , Angulo Eduardo 
Published: March 2010

AbstractThe suitability of a new method to determine the minimum number of data required to stabilize a calculation is studied. Five different calculations have been computed, changing the order of data randomly. The statistical reliability of numerical values has also been calculated depending on the successive increase in the number of data included. In our study, when few data are considered, a great variation in the estimations is observed depending on the individual data included. The calculation is stabilized for a sample size between 5 and 15 data points, and the sample can therefore be considered representative enough. Results are in agreement with those presented by other authors.
Evaluating sediment chemistry and toxicity data using logistic regression modeling
Authors: Field L Jay , MacDonald Donald D , Norton Susan B , Severn Corinne G , Ingersoll Chris G 
Published: March 2010

Abstract
This paper describes the use of logistic-regression modeling for evaluating matching sediment chemistry and toxicity data. Contaminant-specific logistic models were used to estimate the percentage of samples expected to be toxic at a given concentration. These models enable users to select the probability of effects of concern corresponding to their specific assessment or management objective or to estimate the probability of observing specific biological effects at any contaminant concentration. The models were developed using a large database (n = 2,524) of matching saltwater sediment chemistry and toxicity data for field-collected samples compiled from a number of different sources and geographic areas. The models for seven chemicals selected as examples showed a wide range in goodness of fit, reflecting high variability in toxicity at low concentrations and limited data on toxicity at higher concentrations for some chemicals. The models for individual test endpoints (e.g., amphipod mortality) provided a better fit to the data than the models based on all endpoints combined. A comparison of the relative sensitivity of two amphipod species to specific contaminants illustrated an important application of the logistic model approach.
Patterns of groundwater concentration and fate of lindane in an irrigated semiarid area in Argentina
Authors: Ares Jorge O , Miglierina Ana María , Sánchez Ramón 
Published: March 2010

Abstract
The pattern of lindane breakthrough to groundwater and its mobilization thereafter were observed in a semiarid irrigated agricultural basin in southern Argentina. The pesticide half-life in the unsaturated vadose zone and the realized Koc were estimated through parameter optimization techniques on the basis of an ad hoc developed fugacity model, and two existing models of the transport of pesticides in soils (RITZ, PRZM2). Although the estimated half-life values are in agreement with values reported in the literature for other areas, the Koc was lower than usually reported, indicating that the adsorption of the pesticide is controlled by the kinetics of soil water infiltration. The lindane concentration and groundwater conductivity fields over an area of about 2,700 km2 were compared and similarities between the transport of the pesticide and soluble soil salts were inferred. These showed that lindane is transported dissolved in the upper aquifer and can accumulate at exfiltration areas at 10 to 30 km from the sites of its application. The relevance of considering the kinetic constraints imposed by the hydraulic conductivity of the soil profile and the partition with the soil organic matter are highlighted in relation to the prediction of pesticide environmental fate.
Coupling mercury methylation rates to sulfate reduction rates in marine sediments
Authors: King Jeffrey K. , Saunders F Michael , Lee Richard F , Jahnke Richard A 
Published: March 2010

Abstract
Anoxic slurry incubations were performed to examine the relationship between mercury methylation rates (MMR) and sulfate reduction rates (SRR) in salt marsh sediments from the southeastern United States. The MMR and SRR were similarly affected by temperature, addition of low-weight molecular organics, and microbial inhibitors. The MMR was at a maximum in the 12 h after inorganic mercury addition. Initial rates of Hg methylation are correlated with SRR. A significantly slower MMR observed after the initial 12 h following inorganic mercury addition suggested that sorption or precipitation reduced the availability of mercury for methylation. The MMR results for various concentrations of inorganic mercury indicate that saturation kinetics occur. Using this kinetic framework, a model for MMR based on SRR and inorganic Hg concentration was developed. This model was then used to predict the MMR reported in temperature and substrate/inhibitor experiments. The model provided a reasonable estimate of MMR observed in the initial 12 h of the slurry incubations. However, the sequestering of inorganic mercury into less reactive pools by sorption to surfaces or incorporation into other phases alters the amount of bioavailable Hg and hence MMR. Future models that assess the bioavailibility of Hg in the sediments must be developed to extend these observations to field sites.
Influence of ortho-substitution homolog group on polychlorobiphenyl bioaccumulation factors and fugacity ratios in plankton and zebra mussels (Dreissena polymorpha)
Authors: Willman Eric J , Manchester-neesvig Jon B , Agrell Cecilia , Armstrong David E 
Published: March 2010

Abstract
The accumulation of a set of non- and mono-ortho (coplanar) PCB congeners in aquatic ecosystems is of interest due to their dioxin-like toxicities. Chemical properties (octanol-water partition coefficients) suggest that the coplanar congeners may accumulate in organisms to a greater extent than homologs with greater ortho substitution. We analyzed a set of 65 PCB congeners with zero to four ortho-chlorines from seven homolog groups in water, suspended particulate matter, and zebra mussels from Green Bay, Wisconsin, USA, on four dates throughout the ice-free season. The suspended particulate matter was separated by size and characterized as phytoplankton or zooplankton using diagnostic carotenoid pigments and light microscopy. Median bioconcentration factors (BCFs) for accumulation from water by phytoplankton and bioaccumulation factors (BAFs) for accumulation from water plus food by zooplankton and zebra mussels ranged from 1 × 104 to 1 × 106 and were generally the greatest for the tetra- to heptachlorobiphenyls. The average coplanar congener BCFs and BAFs for accumulation from water by phytoplankton, zooplankton, and zebra mussels for the tri-, tetra-, and pentachlorobiphenyls were 54% larger than corresponding values for their homologs. Biomagnification factors (BMFs) of the tetra-, penta-, and hexachlorobiphenyls between zooplankton and zebra mussels and their food source, phytoplankton, typically ranged between 1 and 10, but the average coplanar congener BMFs were 25% less than values for their corresponding homologs. The tendency for coplanar congeners to accumulate to a lesser extent between trophic levels was not as large as their tendency to accumulate from water to a greater extent. Based on accumulation factors, we conclude that the dioxin-like tetra- and pentachlorobiphenyls generally accumulate in the phytoplankton, zooplankton, and zebra mussels of the Green Bay ecosystem to a greater extent than other congeners. Fugacity ratios suggest that, in phytoplankton and zooplankton, homolog concentrations were below equilibrium with water throughout the field season, particularly for the more chlorinated groups, but that concentrations in zebra mussels were at or above equilibrium with water.
Toxicity and bioavailability of the organophosphorus insecticide pirimiphos methyl to the freshwater amphipod Gammarus pulex L. In laboratory and mesocosm systems
Authors: Crane Mark , Attwood Claire , Sheahan Dave , Morris Steven 
Published: March 2010

Abstract
Insecticides must be tested to determine their nontarget toxicity when released into the environment. Currently, new insecticides registered in Europe are likely to be tested, at the highest tier, in microcosms or mesocosms, although the costeffectiveness of these systems has yet to be established. This study investigated the effects of the organophosphorus insecticide pirimiphos methyl on the amphipod Gammarus pulex L. in 250-ml laboratory beakers and 50,000-L pond mesocosms. Acetylcholinesterase activity and survival were used as indicators of the insecticide's bioavailability and toxicity. The results from beakers and mesocosms were indistinguishable, indicating that the former are efficient tools for predicting the bioavailability of chemicals such as pirimiphos methyl that have high toxicity but low persistence in the environment.
Phytotoxicity, uptake, and distribution of [14C] simazine in Canna hybrida ‘Yellow King Humbert’
Authors: Wilson P Chris , Whitwell Ted , Klaine Stephen J 
Published: March 2010

Abstract
Phytoremediation depends on the ability of plants to tolerate and assimilate contaminants. We have been interested in the use of common ornamental plants to ameliorate the impacts of pesticide waste on golf courses and ornamental plant nurseries. This research characterized the interaction between an ornamental, Canna hybrida ‘Yellow King Humbert,’ and the herbicide simazine. Simazine tolerance levels for C. hybrida were determined by exposing plants for 7 d to 0, 0.01, 0.03, 0.1, 0.3, 1.0, or 3.0 mg-simazine/L aqueous nutrient media. Response endpoints included fresh mass production after 7 d of exposure and 7 d postexposure and quantum efficiency using dark-adapted and light-adapted plants. Simazine uptake and distribution within the plant was determined by exposing plants to 2.02 μCi [14C]simazine in nutrient media (0.242 mg/L) for 1, 3, 5, or 7 d. Plant tissues were combusted and analyzed by liquid scintillation counting. Fresh mass production was reduced 66 and 78% for plants exposed to 1.0 and 3.0 mg/L, respectively. Photosynthetic efficiency measured in dark-adapted plants was reduced 34 and 60% at the same respective concentrations, whereas photosynthetic efficiency measured in light-adapted plants was reduced 76 and 92%, respectively. Simazine activity in solution was reduced 80% over 7 d. By day 7, simazine (and/or an impurity) was distributed throughout the plant, but predominantly occurred in the leaves. Uptake of simazine was correlated with water uptake throughout the 7 d. These results suggest that C. hybrida may be a good candidate for incorporation into a phytoremediation scheme for simazine.
Estimating time-to-gravid for a freshwater mussel, Utterbackia imbecillis (Unionidae), after temperature conditioning in the laboratory
Authors: Van Vreede Kelley B , Macintosh David L , Black Marsha C. 
Published: March 2010

Abstract
The juvenile of Utterbackia imbecillis has recently become an important toxicity test organism. However, in temperate climates, gravid U. imbecillis are not readily available during many months of the year, especially if shoreline collection methods are used. This shortage of gravid mussels presents a logistical problem for use of juvenile U. imbecillis as toxicity test organisms. Therefore, this study was designed to test the feasibility of delaying and manipulating glochidial maturation in the laboratory through temperature control, because temperature changes seem to cue the maturation of glochidia in gravid mussels in the natural environment. The objectives of this study were to determine whether glochidial maturation can be stalled by holding adult mussels at cold temperatures, to determine if glochidial maturation could be cued by increasing water temperature at the time juveniles are needed for toxicity testing, and to predict the time required for cold-stored mussels to become gravid (time-to-gravid). Results of this study suggest that glochidial maturation can be stalled by holding mussels at winter temperature. Furthermore, glochidial maturation can later be cued by increasing the water temperature. Additionally, a survival analysis method is suitable for estimating the time-to-gravid for cold-stored mussels. These results should be useful for researchers requiring year-round availability of U. imbecillis for toxicity testing.
Effects of sporophyll storage on giant kelp Macrocystis pyrifera (Agardh) bioassay
Authors: Gully Joseph R , Bottomley Jay P , Baird Rodger B 
Published: March 2010

Abstract
The giant kelp Macrocystis pyrifera (Agardh) is a U.S. Environmental Protection Agency (U.S. EPA)-approved west coast marine species for chronic toxicity monitoring and compliance in the National Pollution Discharge Elimination System (NPDES). The protocol allows field-collected sporophylls to be stored for up to 24 h at 9 to 12°C prior to use. However, the effects of sporophyll storage on the bioassay results have not been fully investigated, particularly with kelp collected from beds south of Point Conception, CA, USA. Therefore, 13 matched-pair reference toxicant bioassays using fresh and stored sporophylls collected from a subtidal kelp bed near Laguna Beach, CA, USA, were performed and compared. The results indicate that a lower percentage of spores germinate and the germ tube lengths are reduced when stored sporophylls are used. The intratest precision of the germination endpoint decreased as evidenced by significant increases in the percent minimum significant difference (%MSD) statistic. The intertest precision also decreased in the germination endpoint as demonstrated by significant increases in the coefficient of variation (CV) values at four effect levels. Conversely, a significant reduction in the CVs was observed in the germ tube length data, possibly as a consequence of the decrease in germ tube length associated with storage. Finally, significant decreases in mean effect concentrations in the germination endpoint in tests using stored sporophylls indicated that storage increased the sensitivity of the spores to the toxic effects of CuCl2. The toxicological sensitivity and intratest precision of the germ tube length endpoint were not significantly affected by storage of the sporophylls. The effects of sporophyll storage resulted in a high frequency of invalid tests, lower statistical power, less effective quality assurance standards, and apparent bias in the observed toxicity of CuCl2.
Is the per capita rate of increase a good measure of population-level effects in ecotoxicology?
Authors: Forbes Valery E , Calow Peter 
Published: March 2010

AbstractIn this paper we consider the relationships between effects of toxicants on population growth rate (r) and the individual-level traits (survival and reproduction) contributing to it by examining population dynamics theory and by reviewing the experimental work that has been carried out in this context. There was no consistent pattern in terms of which individual-level traits were most or least sensitive to toxicant exposure, and it is therefore impractical to select traits for ecotoxicological testing on this basis. Although percent changes in several of the individual-level traits showed significant overall correlations with percent changes in r, changes in any single trait could explain no more than about one-half of the percent change in r. Our conclusion is that r is a better measure of responses to toxicants than are individual-level effects, because it integrates potentially complex interactions among life-history traits and provides a more relevant measure of ecological impact.
Reevaluation of general partitioning model for sorption of hydrophobic organic contaminants by soil and sediment organic matter
Authors: Leboeuf Eugene J , Weber Walter J 
Published: March 2010

AbstractThis evaluation of the polymer-based Flory–Huggins sorption theory has shown that the model predicts relatively concentration-independent χ values for rubbery matrices, concentration-dependent χ values for more glassy matrices, and highly concentration-dependent, largely negative interaction parameters for sorption of phenanthrene onto Green River kerogen, Ohio Shale II kerogen, Illinois No. 6 and Wyoming coals, and poly(phenyl methacrylate). These greatly negative enthalpic contributions to the interaction parameter are only to be expected where specific sorbate-sorbent interactions exist, such as in polar sorbate–polar sorbent systems. The failure of the nonlinear partitioning model is explained in terms of its inability to predict these increased interactions of sorbing solutes within microvoids present within glassy matrices. Calculations of sorbent solubility parameters through use of this model do, however, provide good agreement with literature solubility parameter values for specific sorbents; it may thus prove useful for partial characterization of sorbents for which solubility parameters are unknown.
Nonlinear and interactive effects in the sorption of hydrophobic organic chemicals by sediments
Authors: Jepsen Rich , Lick Wilbert 
Published: March 2010

Abstract
Long-term experiments were done in order to investigate nonlinear isotherms and interactive effects in the sorption of hydrophobic organic chemicals (HOCs) by sediments. In the isotherm experiments, it was demonstrated that the isotherms for all HOCs tested were linear as long as the mass of the sorbed HOC was small by comparison with the mass of organic carbon in the sediments; for larger sorbed HOC concentrations, the isotherms were nonlinear. Sorption experiments also were done with hexachlorobenzene (HCB)–octanol, HCB–ethanol, octanol–ethanol, and HOC–methanol mixtures in water and sediments. Interactive effects were observed and can be described in terms of the partitioning of the primary HOC between the cosolvent, water, and sediments.
Soil factors influencing atrazine sorption: Implications on fate
Authors: Novak Jeffrey M 
Published: March 2010

Abstract
The effects of two soil properties—soil organic carbon (SOC) content and landscape position—and a management factor (tillage) from Iowa and South Carolina soils on the sorption of the herbicide atrazine (6-chloro-N-ethyl-Nǐ-(1-methylethyl)-1,3,5-triazine-2,4-diamine) were evaluated to assess their influence on atrazine fate in the soil environment. In both Iowa and South Carolina, the magnitude of atrazine sorption was strongly and positively correlated with SOC, landscape position, and tillage. Landscape position was especially important for Iowa soils because SOC-enriched depressional areas (potholes) on the Wisconsin glacial surface could sorb more atrazine than soils in sloping positions. Our data suggest that herbicide management strategies such as application rates or herbicide selection will require some adjustments to account for the effects of SOC, landscape position, and tillage management on herbicide sorption in to augment effective weed control and prevent herbicide movement to groundwater.
Sorption and desorption rate comparisons for 1,2-dichlorobenzene to a peat soil
Authors: Deitsch James J , Smith James A 
Published: March 2010

Abstract
The rates of sorption and desorption were quantified for 1,2-dichlorobenzene to and from a peat soil using a batch methodology. Solute—sorbent contact times of 2, 7, 14, 49, and 99 d were studied for the desorption rate experiments. The experimental data were simulated using a distributed rate parameter model. The optimal model fitting parameters and their 95% confidence intervals were computed. The rates of desorption were significantly slower than the rate of uptake for solute–sorbent contact times greater than 2 d. For contact times greater than 2 d, a significant fraction of the 1,2-dichlorobenzene seemed to be irreversibly sorbed. However, the rate of desorption and the magnitude of the irreversible fraction were independent of contact time for contact times greater than 2 d. The rate observations for this study were consistent with an intraorganic matter diffusion mechanism.
Chemical and biological availability of sediment-sorbed hydrophobic organic contaminants
Authors: Lamoureux Elizabeth M , Brownawell Bruce J 
Published: March 2010

Abstract
The ability to predict accumulation levels of sediment-sorbed hydrophobic organic contaminants (HOCs) by depositfeeding organisms based on sediment concentrations is limited in part by an incomplete understanding of the chemistry that controls assimilation efficiency. This study was designed to test the hypothesis that desorption is an important process that controls the bioavailability of HOCs to deposit-feeding organisms; we planned to do so by conducting desorption and bioavailability experiments with field-contaminated sediments collected from New York Harbor, New York, USA. Three classes of organic contaminants, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and linear alkylbenzenes (LABs) were studied. In order to address the effects of contaminant aging, we compared the contaminant desorption rates from sediments collected from surface and at depth in an area of known high-sediment accumulation to retarded intraparticle model predictions. Measured desorption rates of the LABs and the most hydrophobic PCBs compare well with model predictions. However, the PAH and less hydrophobic PCB desorption rates range from one to four orders of magnitude slower than model predictions. We postulate that these compounds are present in a resistant sedimentary phase and may represent only a small fraction of what was originally sorbed. The fraction of PCBs, PAHs, and LABs desorbed after 48 h correlate well with measured biota-sediment factors (BSFs) in Yoldia limatula that were exposed to the same sediments, indicating that desorption rate-limited assimilation. Several studies have related field BSFs with log Kow and have observed a maximum at intermediate Kows (∼6.0-6.5). This maximum may be due to predictably slow desorption of high-Kow compounds and may be lower than predicted rates and extent of desorption of the low-Kow compounds because of association with resistant phases.
A behavioral toxicity test using the ciliated protozoan Tetrahymena thermophila. I. Method description
Authors: Gilron Guy , Gransden Scott G , Lynn Denis H , Broadfoot Jim , Scroggins Richard 
Published: March 2010

Abstract
A novel behavioral toxicity test using the ciliated protozoan Tetrahymena thermophila is described. Tests using a control water (spring water) and two reference toxicant solutions (sodium chloride and guaiacol) yielded reproducible results, indicating that the method has potential as a reliable toxicity test for use in industrial effluent monitoring.