bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ecotoxicological responses of the mayflyBaetis tricaudatusto dietary and waterborne cadmium: Implications for toxicity testing
Authors: Irving Elaine C. , Baird Donald J. , Culp Joseph M. 
Published: March 2010

AbstractTrace metals readily accumulated by stream periphyton may enter aquatic food chains through grazer ingestion. Hence, experiments were conducted to determine the ecotoxicological responses of the grazing mayfly Baetis tricaudatus to dietary cadmium. Short-term feeding experiments indicated that B. tricaudatus nymphs did not initially avoid grazing on cadmium-contaminated diatom mats. During a partial life-cycle experiment, 4 and 10 μg/g of dietary cadmium significantly inhibited grazing, whereas 10 μg/g significantly inhibited growth. Feeding inhibition was the likely mechanism that inhibited growth (i.e., through reduced energy intake). Conversely, when exposed to waterborne cadmium using lethal toxicity test procedures, B. tricaudatus nymphs were relatively tolerant (96-h median lethal concentration, 1,611 μg/L). Thus, sublethal responses to dietary exposure appeared to be more sensitive than lethal responses to waterborne exposure. Because adult mayfly fecundity is a function of nymph size at emergence, dietary cadmium exposure could increase the extinction probability within mayfly populations. The present study highlights the importance of dietary exposure routes in determining the ecotoxicological responses of an organism to a contaminant. Furthermore, the findings emphasize the advantage of evaluating a combination of ecologically relevant, lethal and sublethal endpoints in laboratory methods used to generate data for ecological risk assessment and regulation.
Toxic effects of polychlorinated biphenyl bio accumulation in sea urchins exposed to contaminated sediments
Authors: Zeng Eddy Y. , Bay Steven M. , Greenstein Darrin , Vista Cherrie , Yu Charlie , Ritter Kerry 
Published: March 2010

AbstractThe uptake patterns and toxicity of poly chlorinated biphenyl (PCB) congeners in the white sea urchin, Lytechinus pictus, on exposure to contaminated sediments were investigated. First-order modeling of uptake of the 10 most abundant PCB congeners or domains (containing more than one coeluting congener) by L. pictus indicated that a 35-d exposure was insufficient to reach steady state. Bioaccumulation of PCBs in sea urchins exhibited substantial difference between field and amended sediments, suggesting that caution must be exercised in sample preparation. Some evidence was observed of dependence of measured biota-sediment accumulation factors (BSAFs) on Kow, indicating that equilibrium partitioning of PCBs may not always be achieved between biota lipid, sediment organic carbon, and water. Survival of L. pictus was unaffected by exposure to field and amended sediments with PCB concentrations varying more than three orders of magnitude. The growth measures (diameter, wt, and gonad wt) were significantly reduced in L. pictus exposed to San Diego Bay ([SDB]; San Diego, CA, USA) sediment, whereas they were relatively unaffected after exposure to amended sediments (with much higher PCB concentrations than SDB sediment) prepared from a New Bedford Harbor (MA, USA) sediment. The toxic effects as measured by the growth rates in L. pictus were likely attributable to polycyclic aromatic hydrocarbons (PAHs), which were elevated in SDB sediment (7.3 μg/g), rather than PCBs.
A microcosm system for the study of pollution effects in shallow, sandy, subtidal communities
Authors: Suderman Keith , Thistle David 
Published: March 2010

AbstractThe introduction of pollutants into the marine environment is inevitable, so an understanding of their effects is needed. Because shallow, coastal waters are at greatest risk and many of these shorelines are sandy, a test system for the shallow, sandy, subtidal environment is required. We developed a microcosm system for this purpose and tested it for three months to determine whether the benthic community remained healthy. Furthermore, because long-term effects on the environment occur primarily in the sediment, an experimental method for administering pollutants to the sediment is necessary. We administered a 1-mm layer of clean sand (simulating a technique of administering pollutants as a coating on sand) and tested the benthic community for artifactual effects of the sand itself. Fifteen metrics of community health, including the abundance of benthic microalgae, nematodes, and copepods, were measured. Most metrics were not significantly affected either by containment in the microcosms or by the addition of a 1-mm layer of clean sand. These microcosms are suitable as a test system for the shallow, sandy, subtidal environment.
Availability of metals to the nematode Caenorhabditis elegans: Toxicity based on total concentrations in soil and extracted fractions
Authors: Boyd Windy A. , Williams Phillip L. 
Published: March 2010

Abstract
Current regulation of metals in soils is based on total metal concentrations rather than on actual exposure concentrations. Considering the extreme variation in soil physicochemical properties, total concentrations are not reflective of the availability and resultant toxicity of metals in different soils. In this study, the availability of Cd, Cu, Ni, Pb, and Zn to the free-living soil nematode Caenorhabditis elegans was assessed after 24-h exposures in three soils using a sequential soil extraction procedure. Albany soil, sampled from southern Georgia, USA, is characterized by a high sand content, whereas Cecil soil from the Piedmont region of Georgia contains higher fractions of clay and organic matter. The final soil was an American Society for Testing and Materials (ASTM) artificial medium composed of peat, kaolin clay, sand, and calcium carbonate. Based on their composition, ASTM medium would sorb metals most strongly and Albany soil the least strongly. In fact, 24-h lethal concentrations to 50% (LC50s) of nematodes for the five metals as determined by the total metal concentration followed this trend. In addition, water-extractable metals were lowest in ASTM medium and highest in Albany soil when spiked at the same concentrations. Our data show the need to consider soil type when performing toxicological tests and establishing site-specific allowable metal concentrations in soil.
1-hydroxypyrene glucuronide as the major aqueous pyrene metabolite in tissue and gut fluid from the marine deposit-feeding polychaete Nereis diversicolor
Authors: Giessing Anders M. B. , Mayer Lawrence M. , Forbes Thomas L. 
Published: March 2010

Abstract
Both 1-hydroxypyrene and 1-hydroxypyrene glucuronide are identified as the primary phase I and phase II metabolites of the four-ringed polycyclic aromatic hydrocarbon (PAH) pyrene in the marine deposit-feeding polychaete Nereis diversicolor. Identification of pyrene and primary metabolites was performed using high-pressure liquid chromatography (HPLC) with diode-array detection and fluorescence detection (HPLC/DAD/F) and an ion-trap mass spectrometer for positive identification of 1-hydroxypyrene glucuronide. Besides 1-hydroxypyrene and 1-hydroxypyrene glucuronide, the HPLC/F trace of tissue samples from pyrene-exposed worms showed three additional low-intensity peaks that may be related to pyrene metabolism based on similar excitation/emission wavelengths. The peaks were all too low in intensity to be positively identified. Of the total PAH in tissue, 1-hydroxypyrene glucuronide, 1-hydroxypyrene, and pyrene constituted 73%, 2%, and 25% respectively. Gut elimination of metabolic products is supported by the identification of 1-hydroxypyrene and 1-hydroxypyrene glucuronide in both gut fluid and defecation water. Being the only phase I metabolite of pyrene, 1-hydroxypyrene becomes a useful marker for PAH exposure, and it may serve as a valuable model compound for assessing species-specific PAH metabolic capabilities.
Effect of cortisol treatment and/or sublethal copper exposure on copper uptake and heat shock protein levels in common carp,Cyprinus carpio
Authors: De Boeck Gudrun , De Wachter Bart , Vlaeminck Andrea , Blust Ronny 
Published: March 2010

AbstractThis study compared the effects of increased endogenous cortisol levels and/or sublethal Cu exposure on Cu accumulation and stress protein levels (HSP70) in the freshwater common carp, Cyprinus carpio. Fish were exposed to either increased levels of endogenous cortisol (200 ng/ml) or sublethal Cu concentrations (1.9 μM, ∼20% of the acute 96-h median lethal concentration [LC50]) alone or were pretreated by elevating plasma cortisol levels prior to Cu exposure to evaluate whether interactions between both treatments occurred. Cortisol resulted in decreased Cu levels and a decreased Cu accumulation on a short-term basis (4 h). After 96 h of Cu exposure, cortisol pretreatment resulted in augmented Cu accumulation. Exposure to Cu increased HSP70 levels in gills, erythrocytes, and liver and decreased levels in brain and kidney. No clear relationship to Cu tissue levels was observed. Increased cortisol levels or treatment with cortisol before Cu exposure decreased the HSP70 response. We can conclude that cortisol elevation results in a lower HSP70 response and thus reduces the protection against cellular stress during metal accumulation. After an initial decrease in Cu accumulation, cortisol elevation eventually stimulates metal accumulation.
Effects of agricultural pesticides on the immune system of Rana pipiens and on its resistance to parasitic infection
Authors: Christin Marie-Soleil , Gendron Andrée D. , Brousseau Pauline , Ménard Lucie , Marcogliese David J. , Cyr Daniel , Ruby Sylvia , Fournier Michel 
Published: March 2010

Abstract
In the past 30 years, many amphibian species have suffered population declines throughout the world. Mass mortality have been frequently reported, and in several instances, infectious diseases appear to be the cause of death. The role that contaminants could play in these die-offs through immunotoxic effects has been poorly investigated. In this study, juvenile leopard frogs (Rana pipiens) were exposed for 21 d to a mixture of six pesticides (atrazine, metribuzin, aldicarb, endosulfane, lindane, and dieldrin) and subsequently challenged with a parasitic nematode, Rhabdias ranae. Exposure to the mixture at environmentally realistic concentrations significantly reduced lymphocyte proliferation. Three weeks after the end of the exposure, lymphocyte proliferation had recovered and was stimulated in frogs challenged with parasites with the exception of those previously exposed to the highest concentration. No pesticide effects on phagocytosis and splenocyte numbers were detectable at the end of the exposure period, but these two parameters were diminished 21 d after the infection challenge in frogs previously exposed to the highest levels of pesticides. In these animals, the prevalence of lung infection by R. ranae also tended to be higher. These results suggest that agricultural pesticides can alter the immune response of frogs and affect their ability to deal with parasitic infection.
Exposure of small mammals, in particular the wood mouse Apodemus sylvaticus, to pesticide seed treatments
Authors: Barber Ian , Tarrant Kenneth A. , Thompson Helen M. 
Published: March 2010

Abstract
Field exposure of small mammals to fungicide-treated wheat seed was investigated over three weeks following drilling on fields near York, United Kingdom. Seed consumption by small mammals trapped on and immediately adjacent to the drilled fields was quantified by measuring the amount of seed in the stomach. In addition, exposure to one seed-treatment, fluquinconazole, was quantified by measuring residues of the fungicide in the stomach, liver, and intestine. The wood mouse, Apodemus sylvaticus, was the dominant species caught on the fields and the only species found to have consumed measurable quantities of seed. Voles, Microtus agrestis and Clethrionomys glareolus, were caught in small numbers, almost exclusively in the field hedge, and showed no evidence of having consumed seed. Stomach-contents analysis revealed that more than 80% of animals trapped in the hedge adjacent to the field had consumed no wheat seed, whereas 98% had consumed less than 10% (by stomach volume). Ninety percent of animals trapped on the field had consumed seed, although 90% of these animals had less than 20% seed in the stomach. Residues of the fungicide in the stomach, intestine, and liver were lower than would be expected for the amount of seed consumed, possibly because of dehusking of the seeds by mice. The relevance of these findings when assessing exposure (and risk) posed by seed treatments to wild mammals is discussed.
Bioavailability of uranium and nickel to vegetation in a contaminated riparian ecosystem
Authors: Punshon Tracy , Gaines Karen F. , Bertsch Paul M. , Burger Joanna 
Published: March 2010

Abstract
The lower portion of Tims Branch (TB), a second-order stream system on the Savannah River site (SC, USA), receives influx of mixed waste-contaminated sediments from Steed Pond, a former settling basin for target processing wastes for over three decades. The magnitude and distribution of U, Ni, and other metals and the potential for trophic movement were studied to facilitate risk assessment and determine potential remedial action. Total and sequential extraction of TB soils demonstrated contaminant heterogeneity both spatially and between operationally defined fractions. Metal concentrations were elevated within riparian zone soils in contrast to stream sediments, suggesting off-site transport. Leaf tissue from TB contained an order of magnitude more Ni than tissue from reference sites. Leaves from streamside trees contained no U but elevated Ni up to 75.4 (±25) mg/kg dry weight (dry wt). Understory flora (Discanthelium sp. and Andropogon sp.) contained high concentrations of U associated with leaves up to 518 (±7.5) mg/kg dry weight U. The contrast in contaminant content and ratio of streamside and understory vegetation may result from resuspension of particulate U and Ni onto leaf surfaces and represents a potential pathway for trophic movement. The findings of this study have important ramifications for remediation of the ecosystem, suggesting that a strategy based on contaminant immobilization may be the most appropriate.
Accumulation of cadmium by durum wheat roots: Bases for citrate-mediated exceptions to the free ion model
Authors: Berkelaar Edward , Hale Beverley A. 
Published: March 2010

AbstractThe accumulation of Cd in durum wheat (Triticum turgidum) roots from hydroponic solutions, with the proportion of total Cd (8.9–445 nM Cd) as Cd2+ varied by the addition of citrate, was determined to test the free-ion model (FIM) of metal bioavailability for higher plants. Calcium, Mg, and K were also varied. Citrate enhanced root-Cd accumulation at higher Cd2+ concentrations but not lower relative to the same Cd2+ concentrations in solutions containing 0 mM citrate. Elevating Ca2+ and Mg2+ concentrations in the citrate solution to the same as those in control solutions alleviated some of the citrate-mediated enhancement but not all. Solutions containing 66% less Ca or Mg than control but the same Cd2+ concentration and no citrate also resulted in increased root Cd. Elevated K+ did not influence Cd accumulation. Regression relationships between root-Cd accumulation and total Cd in solution were similar for the control and pooled amended solutions, whereas they were different for root-Cd accumulation and solution Cd2+. These results contribute to the growing body of evidence that the FIM alone is likely insufficient to predict plant accumulation of metals from soils, although it may be a useful probe for the mechanistic bases of metal bioavailability.
Using a freshwater amphipod in situ bioassay as a sensitive tool to detect pesticide effects in the field
Authors: Schulz Ralf 
Published: March 2010

Abstract
In situ testing represents an alternative to conventional laboratory toxicity testing of field samples. Juvenile Paramelita nigroculus (Crustacea: Amphipoda) were exposed in situ in two rivers downstream of fruit orchard areas in the Western Cape, South Africa. Exposure took place during six time intervals (3–7 d), of which three represented the first rainfall-induced edge-of-field runoff events of the wet season, which was about two months after the last pesticide application. Survival rates were significantly reduced (35–70%) during runoff events 1 and 2 at both sites. No difference was observed from the respective no-runoff survival rate (&gt;90%) during event 3. Peak levels of total insecticides (azinphosmethyl, chlorpyrifos, endosulfan, and prothiofos) in samples taken with water level-triggered samplers during the runoff events were between 0.03 and 0.26 μg/L in filtered water and between 305 and 870 μg/kg in suspended particles during runoff events 1 and 2 and only up to 0.01 μg/L and 101 μg/kg during event 3. Total suspended solids (TSS) varied between 400 and 700 mg/L during all three runoff events but never exceeded 65 mg/L during no-runoff time intervals. A laboratory experiment revealed that uncontaminated TSS levels of 1,500 mg/L during a 7-d exposure caused insignificant mortality (&lt;2.5%) in P. nigroculus. No acute toxicity was observed in standard 48-h toxicity tests with juvenile Daphnia pulex using the filtered water samples taken during runoff and no-runoff conditions. It is concluded that the observed mortalities were caused by particle-associated pesticides and that the present amphipod in situ bioassay represents a sound and sensitive tool to detect runoff-related insecticide effects under field conditions.
Influence of desorption and contact time on sediment-water distribution of spiked polychlorinated biphenyls and polycyclic aromatic hydrocarbons: Relation with in situ distribution
Authors: ten Hulscher Theodora , Vrind Bea , van den Heuvel Henny , van Noort Paul , Govers Harrie 
Published: March 2010

Abstract
The long-term sediment—water distribution of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs), spiked to Lake Ketelmeer (The Netherlands) sediment, was studied using a gas-purge technique. Contact times varied from 2 to 1,461 d for the PCBs and from 5 to 100 d for the PAHs. Purge-induced desorption experiments lasted 300 to &lt;4,000 h. The initial distribution coefficients that were observed during the first part of the experiment were close to literature values for distribution after short contact times. The distribution coefficients increased during the purge-induced desorption experiments. The final distribution coefficients that were observed during the last part of the experiment were one to two orders of magnitude higher than the initial values and were close to distribution coefficients reported earlier for in situ PCBs and PAHs present in a field-contaminated sediment for years to decades. The change in distribution coefficients during a gas-purge experiment may resemble the long-term change in a field sediment. Final distribution coefficients seem to be a more relevant measure for the distribution coefficients of hydrophobic organic chemicals in aged field sediments than values obtained after short contact times.
Air—water gas exchange of toxaphene in Lake Superior
Authors: Jantunen Liisa M. , Bidleman Terry F. 
Published: March 2010

Abstract
Parallel air and water samples were collected in Lake Superior during August 1996 and May 1997, to determine the levels and air—water exchange direction of toxaphene. Concentration of toxaphene in water did not vary across Lake Superior or between seasons (averaging 918 ± 218 pg/L) but atmospheric levels were lower in May (12 ± 4.6 pg/m3) than in August (28 ± 10 pg/m3). Two recalcitrant congeners, Parlar 26 and 50, also were determined. These congeners were enriched in the air samples, compared to a standard of technical toxaphene, but not in the water. Water—air fugacity ratios varied from 1.4 to 2.6 in August and 1.3 to 4.7 in May, implying volatilization of toxaphene from the lake. Estimated net fluxes ranged from 5.4 to 13 and 1.8 to 6.4 ng/m2d, respectively. The temperature dependence of toxaphene partial pressure (P) in air was log P/Pa = −3,291/Ta + 1.67, where Ta is air temperature. By using this relationship, the atmospheric levels of toxaphene, fugacity ratios, and net fluxes were estimated for the entire year. Fugacity ratios were highest in the winter and lowest in the summer; thus toxaphene was predicted to undergo net volatilization from the lake during all months. A net removal of approximately 220 kg/year by gas exchange was estimated.
Incomplete degradation of polycyclic aromatic hydrocarbons in soil inoculated with wood-rotting fungi and their effect on the indigenous soil bacteria
Authors: Andersson B. Erik , Lundstedt Staffan , Tornberg Karin , Schnürer Ylva , Öberg Lars G. , Mattiasson Bo 
Published: March 2010

Abstract
Soil artificially contaminated with fluorene, phenanthrene, pyrene, and benz[a]anthracene was inoculated with the wood-rotting fungi Pleurotus ostreatus and Antrodia vaillantii. During 12 weeks of incubation, polycyclic aromatic hydrocarbon (PAH) degradation and the formation of persistent degradation products were monitored by chemical analysis. In addition, the effect on the indigenous soil bacteria was studied by plate count techniques and by measuring the concentration of bacteria-specific phospholipid fatty acids (PLFAs). In both soils inoculated with fungi, the PAH degradation was enhanced compared to the control soil without fungi. The white-rot fungus P. ostreatus accelerated the degradation rate radically the first weeks, while the effect of the brown-rot fungus was more pronounced at later stages during the 12-week study. In a soil with no amendments, the final degradation result was similar to that in the soil with added fungi, although the degradation pattern for the individual PAHs was different. Furthermore, the degradation by P. ostreatus was accompanied by an accumulation of PAH metabolites, that is, 9-fluorenone, benz[a]anthracene-7,12-dione, and two compounds identified as 4-hydroxy-9-fluorenone and 4-oxapyrene-5-one, that was not seen in the other soils. The inoculation with the white-rot fungus also had a large negative effect on the indigenous soil bacteria. This could be an important drawback of using the white-rot fungus P. ostreatus in soil bioremediation since a sequential fungal—bacterial degradation probably is needed for a complete degradation of PAHs in soil. In the soil inoculated with A. vaillantii, on the other hand, no metabolites accumulated, and no negative effects were observed on the indigenous microorganisms.