bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence of pesticide impacts in the Santa Maria River watershed, California, USA
Authors: Anderson Brian S. , Phillips Bryn M. , Hunt John W. , Worcester Karen , Adams Mary , Kapellas Nancy , Tjeerdema Ron S. 
Published: March 2006

AbstractThe Santa Maria River provides significant freshwater and coastal habitat in a semiarid region of central California, USA. We conducted a water and sediment quality assessment consisting of chemical analyses, toxicity tests, toxicity identification evaluations, and macroinvertebrate bioassessments of samples from six stations collected during four surveys conducted between July 2002 and May 2003. Santa Maria River water samples collected downstream of Orcutt Creek (Santa Maria, Santa Barbara County, CA, USA), which conveys agriculture drain water, were acutely toxic to cladocera (Ceriodaphnia dubia), as were samples from Orcutt Creek. Toxicity identification evaluations (TIEs) suggested that toxicity to C. dubia in Orcutt Creek and the Santa Maria River was due to chlorpyrifos. Sediments from these two stations also were acutely toxic to the amphipod Hyalella azteca, a resident invertebrate. The TIEs conducted on sediment suggested that toxicity to amphipods, in part, was due to organophosphate pesticides. Concentrations of chlorpyrifos in pore water sometimes exceeded the 10-d median lethal concentration for H. azteca. Additional TIE and chemical evidence suggested sediment toxicity also partly could be due to pyrethroid pesticides. Relative to an upstream reference station, macroinvertebrate community structure was impacted in Orcutt Creek and in the Santa Maria River downstream of the Creek input. This study suggests that pesticide pollution likely is the cause of ecological damage in the Santa Maria River.
Photoinduced toxicity of polycyclic aromatic hydrocarbons toDaphnia magna: Ultraviolet-mediated effects and the toxicity of polycyclic aromatic hydrocarbon photoproducts
Authors: Lampi Mark A. , Gurska Jolanta , McDonald Kristina I. C. , Xie Fangli , Huang Xiao-Dong , Dixon D. George , Greenberg Bruce M. 
Published: March 2006

AbstractPolycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants known for their photoinduced toxicity. This toxicity may occur through two mechanisms: Photosensitization, and photomodification. Photosensitization generally leads to the production of singlet oxygen, a reactive oxygen species that is highly damaging to biological molecules. Photomodi-fication of PAHs, usually via oxidation, results in the formation of new compounds and can occur under environmentally relevant levels of actinic radiation. The toxicities of 16 intact PAHs to Daphnia magna were assessed under two ultraviolet radiation conditions. The toxicity of intact PAHs generally increased in the presence of full-spectrum simulated solar radiation relative to that in the presence of visible light plus ultraviolet A only. Despite the knowledge of a bipartite mechanism of phototoxicity that includes photosensitization and photomodification, few studies have examined the effects of PAH photoproducts on animals. To expand the existing data, 14 PAH photoproducts (oxy-PAHs) also were assayed, most of which were highly toxic without further photomodification. Two photoproducts of benzo[a]pyrene, 1,6- and 3,6-benzo[a]pyrenequinone, were the most toxic compounds tested, followed closely by benz[a]anthraquinone. Each of these three compounds had a median effective concentration in the low nanomolar range. The data presented highlight the effects of ultraviolet radiation on mediating PAH toxicity and the need to analyze absorption spectra of contaminants in the prediction of photoinduced toxicity. The importance of the role of photomodification also is stressed, because several oxy-PAHs, an unregulated group of contaminants, were highly toxic to D. magna, a key bioindicator species in aquatic ecosystems.
Body residues as dose for sublethal responses in alevins of landlocked salmon (Salmo salarm.sebago): A direct calorimetry study
Authors: Penttinen Olli-Pekka , Kukkonen Jussi V. K. 
Published: March 2006

AbstractQestions of organism-specific factors, toxicity endpoints, and their relation to mode-of-action all are related to consistency and applicability of body residue-based approaches. To address this issue, direct calorimetry was used to evaluate metabolic responses of alevins of landlocked salmon (Salmo salar m. sebago) to pentachlorophenol (PCP) exposure ranging from 0 to 1.04 μM for 24 h or 24, 48, and 72 h (0, 0.26, and 0.55 μM, respectively). The body residues were used as a dose metric for sublethal responses. The body size, rapid ontogenetic development, and exposure to a specific pollutant all were heat output-modifying factors. The acute exposure (24–72 h) to PCP led to a heat output-enhancing effect, which directly was related to an internal concentration of PCP in the range of 0.01 to 0.15 μmol/g. Within the treatments, body size per level of metabolic rate and magnitude of physiological response were not correlated, thus the alevins with higher mass-specific metabolic rate were not more sensitive to PCP. Primarily, increasing metabolic rate during posthatch development controls PCP toxicity only by affecting bioaccumulation kinetics, not the toxic potency of the chemical. New information of a relationship between observed natural variation in measured physiological trait offish and PCP-induced response and its body residue-based level is of ecotoxicological importance.
Predicted effects of toxicant mixtures are confirmed by changes in fish species assemblages in Ohio, USA, rivers
Authors: Posthuma Leo , de Zwart Dick 
Published: March 2006

AbstractThe purposes of this study were to investigate whether exposure to toxicant mixtures is associated with fish assemblage characteristics in the field and to describe the relationships between predicted chronic and acute mixture risks and observed impacts. Fish abundance and abiotic monitoring data from Ohio, USA, surface waters were compiled and analyzed. Variability of biotic and abiotic parameters was large. Exposure assessment, risk assessment with species-sensitivity distributions, and mixture toxicity rules were used to calculate a relative risk predictor: The multisubstance potentially affected fraction of species (msPAF). Predicted acute and chronic risks ranged from low values to more than 10 and 50% of species potentially affected, respectively. Pearson correlations between predicted risk and observed assemblage characteristics were nonsignificant for total abundance, number of species, Shannon-Weaver index, and evenness. Moderately significant correlations were found between predicted risk and abundance for 23% of individual species. Both abundance increases and decreases were observed. Generalized linear model (GLM) regressions revealed significant nonlinear associations between predicted risk and the abundance for 50% (metals and ammonia) and 55% (household product ingredients) of the species. Local ecological impact was expressed as the fraction of species expected but not observed, both with and without attribution of impact to mixture exposure. The association between predicted impacted fraction and the fraction of species expected but not observed was not significant. Predicted acute and chronic impacted fractions were associated significantly with the observed fraction of species likely lost by the action of toxicant mixtures under field conditions, with wide confidence bounds. These findings confirm the view that higher mixture impacts are expected in the field at higher msPAF.
A meta-analysis comparing the toxicity of sediments in the laboratory and in situ
Authors: Hose Grant C. , Murray Brad R. , Park Margaux L. , Kelaher Brendan P. , Figueira Will F. 
Published: March 2006

AbstractSediment toxicity tests in the laboratory are an important part of ecological risk assessments, yet how they relate to sediment toxicity in situ has rarely been explored. Using meta-analysis, we examined differences in the toxicity of sediment tested in the laboratory and in situ. Data from four published studies were subjected to rigorous statistical analyses. Overall, the toxicity of sediments in laboratory tests was substantially less than their toxicity in situ. Differences between laboratory and in situ toxicity, expressed using the log odds ratio effect size, varied significantly among published studies. Effect size increased significantly with increasing sediment toxicity, showing that the more toxic the sediment, the greater the disparity between laboratory and field toxicities. Our findings may not apply to all laboratory/field comparisons; however, we consider that the overlying water in field situations is a significant contributor to this relationship through additional contamination and toxicity. Our findings also have important implications for the use of laboratory tests to assess improvements in sediment quality and remediation, because changes in laboratory toxicity may not reflect the true improvements to sediment quality in situ.
Use of carboxylesterase activity to remove pyrethroid-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in toxicity identification evaluations
Authors: Wheelock Craig E. , Miller Jeff L. , Miller Mike J. , Phillips Bryn M. , Huntley Sarah A. , Gee Shirley J. , Tjeerdema Ronald S. , Hammock Bruce D. 
Published: March 2006

Abstract
Increases in the use and application of pyrethroid insecticides have resulted in concern regarding potential effects on aquatic ecosystems. Methods for the detection of pyrethroids in receiving waters are required to monitor environmental levels of these insecticides. One method employed for the identification of causes of toxicity in aquatic samples is the toxicity identification evaluation (TIE); however, current TIE protocols do not include specific methods for pyrethroid detection. Recent work identified carboxylesterase treatment as a useful method for removing/detecting pyrethroid-associated toxicity. The present study has extended this earlier work and examined the ability of carboxylesterase activity to remove permethrin- and bifenthrin-associated toxicity to Ceriodaphnia dubia and Hyalella azteca in a variety of matrices, including laboratory water, Sacramento River (CA, USA) water, and Salinas River (CA, USA) interstitial water. Esterase activity successfully removed 1,000 ng/L of permethrin-associated toxicity and 600 ng/L of bifenthrin-associated toxicity to C. dubia in Sacramento River water. In interstitial water, 200 ng/L of permethrin-associated toxicity and 60 ng/L of bifenthrin-associated toxicity to H. azteca were removed. The selectivity of the method was validated using heat-inactivated enzyme and bovine serum albumin, demonstrating that catalytically active esterase is required. Further studies showed that the enzyme is not significantly inhibited by metals. Matrix effects on esterase activity were examined with municipal effluent and seawater in addition to the matrices discussed above. Results confirmed that the esterase retains catalytic function in a diverse array of matrices, suggesting that this technique can be adapted to a variety of aquatic samples. These data demonstrate the utility of carboxylesterase treatment as a viable step to detect the presence of pyrethroids in receiving waters.
Bioavailability of polycyclic aromatic hydrocarbons from buried shoreline oil residues thirteen years after theExxon Valdezoil spill: A multispecies assessment
Authors: Neff Jerry M. , Bence A. Edward , Parker Keith R. , Page David S. , Brown John S. , Boehm Paul D. 
Published: March 2006

AbstractSeven taxa of intertidal plants and animals were sampled at 17 shoreline sites in Prince William Sound ([PWS]; AK, USA), that were heavily oiled in 1989 by the Exxon Valdez oil spill (EVOS) to determine if polycyclic aromatic hydrocarbons (PAH) from buried oil in intertidal sediments are sufficiently bioavailable to intertidal prey organisms that they might pose a health risk to populations of birds and wildlife that forage on the shore. Buried residues of EVOS oil are present in upper and middle intertidal sediments at 16 sites. Lower intertidal (0 m) sediments contain little oil. Much of the PAH in lower intertidal sediments are from combustion sources. Mean tissue total PAH (TPAH) concentrations in intertidal clams, mussels, and worms from oiled sites range from 24 to 36 ng/g (parts per billion) dry weight; sea lettuce, whelks, hermit crabs, and intertidal fish contain lower concentrations. Concentrations of TPAH are similar or slightly lower in biota from unoiled reference sites. The low EVOS PAH concentrations detected in intertidal biota at oiled shoreline sites indicate that the PAH from EVOS oil buried in intertidal sediments at these sites have a low bioavailability to intertidal plants and animals. Individual sea otters or shorebirds that consumed a diet of intertidal clams and mussels exclusively from the 17 oiled shores in 2002 were at low risk of significant health problems. The low concentrations of EVOS PAH found in some intertidal organisms at some oiled shoreline sites in PWS do not represent a health risk to populations of marine birds and mammals that forage in the intertidal zone.
Kinetics of adsorption and desorption of some organochlorine compounds on black carbon in a sediment
Authors: Vrind Bea A. , ten Hulscher Theodora E. M. , van Noort Paul C. M. 
Published: March 2006

AbstractRate constants for adsorption and desorption of four organochlorine compounds on black carbon in a sediment were determined from measurements of the rate of removal, by gas purge, of the organochlorine compounds as single solutes from a water-sediment mixture immediately after addition of the solute to the system. The rates of removal fitted to a kinetic scheme based on Langmuir adsorption onto two types of sites in black carbon. The first-order rate constants for desorption from these sites were comparable to those for slow and very slow desorption from sediment. The time needed to reach apparent equilibrium in the experimental setup, with 10 g sediment/L water, ranged from 13 to 166 h, depending on the sorbate and the adsorption process. These short times to equilibrium suggest no need to assume rate-limiting diffusion from and to adsorption sites in this sediment. Average Gibbs free energies for adsorption of the four organochlorine compounds from the pure solid state were —10 ± 3 and —20 ± 3 kJ/mol for low-energy and high-energy sites, respectively, pointing to two different adsorption mechanisms.
SOME EFFECTS OF RESPONSE COST UPON HUMAN OPERANT BEHAVIOR
Authors: Weiner Harold 
Published: March 2006

Three experiments are reported which investigated the effects of cost (point loss per response) upon human‐observer responses maintained by VI and FI schedules of reinforcement (acquisition of points via critical‐signal detections). (I) Cost attenuated VI response rates without substantially disturbing the constancy of responding, regardless of the presentation sequence of the no‐cost and cost conditions. (II) FI scalloping appeared only under cost conditions. Under no cost, a constant rate of responding (similar to VI performance) characterized inter‐reinforcement intervals. Exposure to cost did not prevent the recovery of previously established no‐cost baselines. (III) FI irregularities, analogous to those commonly observed under FI reinforcement schedules, may be produced by different temporal presentations of the no‐cost and cost conditions.The results of all three experiments emphasize the importance of cost as a factor in the maintenance of human behavior on schedules of positive reinforcement.
FOOD SATIATION IN THE PIGEON
Authors: Reese T. W. , Hogenson Marilyn J. 
Published: March 2006

The experiment was designed to find the shape of food satiation curves of the pigeon as a function of hours of deprivation or percentage of free‐feeding weight, and to study the fluctuation in free‐feeding weight as a function of deprivation and satiation. At a systematically and progressively increased number of hours' deprivation, eight birds were allowed to satiate on grain presented contingent upon the emission of a pecking response. In the second part of the experiment, in which two birds were used, a similar procedure was followed except that the independent variable was percentage of free‐feeding weight. These were the conclusions.
. Approximately 64% of the satiation curves were classified as straight with an abrupt stop. The next highest percentage of curves was 18% for curves classified as straight with a curvilinear stop. No “classic” satiation curves, curvilinear with curvilinear stop, were found.
. The pigeons responded at fairly constant rate during the early part of each satiation session, or they did not respond at all. The critical weight, above which they did not respond, was 85% of free feeding.
MACHINE DEFINITION OF ONGOING SILENT AND ORAL READING RATE1
Authors: Goldiamond Israel 
Published: March 2006

A procedure is described by which a machine defines the ongoing silent and oral reading rates, and thus subjects them to environmental control and experimental analysis. Reading is considered as a form of monitoring in which response sequences are linear and successive. Applications for other types of monitoring are considered.A page is projected on a screen, and the subject is required to read, aloud or silently. Through the same optical system, an opaque loop is presented that masks the projection, and a transparent slit on the opaque loop exposes part of a line of type. With each frame, the slit moves linearly and sequentially, exposing successive reading material. Recycling the loop triggers the presentation of another page. The subject controls the loop by pressing a microswitch to advance the frame, thereby explicitly defining a monitoring response. The procedure is sensitive to variables such as signal‐noise ratio, item difficulty, transient and long‐term effects, reinforcement schedules (pay‐offs), and age. Monitoring rates are extremely steady, suggesting their use as a base line.Procedures are suggested for training subjects to be differentially attentive to different parts of a complex display.
THE OPERANT CONTROL OF VOCALIZATION IN THE DOG1
Authors: Salzinger Kurt , Waller Marcus B. 
Published: March 2006

Control over the vocal responses of three dogs was established using operant‐conditioning procedures. Several points of interest were observed in the data. First, fixed‐ratio schedules of reinforcement generated a vocal response topography which was similar in detail to that of a “motor” bar‐nosing response. Second, vocal responding was brought under the control of external visual stimuli as a result of differential reinforcement. Third, good stimulus control was maintained on a multiple schedule containing a vocal‐response component and a bar‐response component. Fourth, the stimulus control on the multiple schedule transferred with minimal disruption to a chain schedule requiring a sequence of 10 bar responses followed by 10 vocal responses. Fifth, because vocal and bar responses are not mutually exclusive, concurrent responding tended to develop on the chain schedule.These results were discussed with reference to the advisability of applying the terms operant and respondent to unconditioned behavior, and, particularly, to unconditioned verbal behavior.
Interactions between zinc and cadmium uptake by free and immobilized cells of Scenedesmus quadricauda (Turp.) Breb.
Authors: Awasthi Mamta , Rai Lal Chand 
Published: March 2006

AbstractBiological treatment of heavy metals is an effective technology for the treatment of low concentration industrial wastewater. The purpose of this study was to evaluate the zinc and cadmium removal capacities through absorption (active) and adsorption (passive) by free and alginate‐immobilized cells of Scenedesmus quadricauda. Immobilized cells have high capacities for uptake of both the heavy metal tested and the kinetics under the conditions studied were relatively fast. About 90% of the biosorption (adsorption) occurred within 10 min and equilibrium was reached within 30 minutes in both free and immobilized cells. However, a different pattern was observed for absorption. Maximum absorption by immobilized cells was found to be around 6.6 mmol Zn2+ and 8.0 mmol Cd2+ per mg protein, these values being approximately 1.4 and 1.6 fold higher than those of the free cells. Statistical analysis (ANOVA) confirmed the superiority of immobilized cells for metal absorption but not for adsorption. Free cells were equally good for adsorption. The results obtained on the patterns of metal/metal interactions showed either antagonistic, or non‐interaction type of behaviour for both adsorption and absorption. However, no synergistic type of behaviour was observed during treatment.
Effects of single and mixed diatom diets on the reproduction of copepod Calanus sinicus
Authors: Li Jie , Sun Song , Li Chao‐lun , Zhang Zhan , Tao Zheng‐Cheng 
Published: March 2006

AbstractUnder laboratory conditions, the potential influence of diatom diets on reproduction of zooplankton Calanus sinicus was studied. Four diatom diet ingredients: Skeletonema costatum (SC), Chaetoceros muelleri (CM), Phaeodactylum tricornutum (PT), diatom mixture (MIX) and a control diet: the flagellate Platymonas subordiformis (PS), were used at the same carbon concentrations of 2.0 μg mL–1 C. In a period of 17‐day laboratory experiment, the effects of these algae diets on egg production and hatching success of the copepod Calanus sinicus were examined. The diets were analyzed for fatty acid content as an indicator of food quality. The results showed that the female survival of all treatments reached more than 80% except PT. Comparing to the initial value, egg production of Calanus sinicus was reduced in diatom diets (PT, CM), but remained in normal level in SC and MIX, indicating that some single diatom diets had a negative effect on the egg production of Calanus sinicus. Feeding with mixed food however can eliminate this negative effect. Among all the treatments, hatching success in filtered seawater was significantly higher than in algal exudates, indicating that not only diatoms but also other phytoplankton in certain concentration can release extracelluar substance that may inhibit eggs from hatching. Fatty acid analysis showed that both egg production rate and hatching success were negatively correlated to the ratio of 20 : 5 ω3 and 14 : 0 in fatty acid composition.