bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproduction success of American kestrels exposed to dietary polychlorinated biphenyls
Authors: Fernie Kimberly J. , Smits Judit E , Bortolotti Gary R , Bird David M 
Published: March 2010

Abstract
While reproduction of wild birds is adversely affected by multiple environmental contaminants, we determined that polychlorinated biphenyls (PCBs) alone alter reproduction. Captive American kestrels (Falco sparverius), fed PCB-spiked (Aroclor® 1248:1254:1260) food (7 mg/kg body weight/d) prior to and during the first breeding season only (100 d) laid eggs with environmentally relevant levels of total PCBs (34.0 μg/g whole egg wet wt vs 0 μg/g for controls). Reproduction changed during, not after, PCB exposure in this two-year study. The PCB-exposed pairs laid smaller clutches later in the season and laid more totally infertile clutches. Hatching success was reduced in PCB-exposed pairs, and 50% of PCB nestlings died within 3 d of hatching. Nearly 60% of PCB-exposed pairs with hatchlings failed to produce fledglings. Higher levels of total PCB residues and congeners were associated with later clutch initiation and fewer fertile eggs, hatchlings, and fledglings. We suggest that nonpersistent PCB congeners have a greater influence on reproduction than do persistent congeners.
Comparing representations of the environmental spatial scale of organic chemicals
Authors: Beyer Andreas , Scheringer Martin , Schulze Carsten , Matthies Michael 
Published: March 2010

Abstract
Long-range transport potential is one of the criteria proposed to identify chemicals as persistent organic pollutants. Here, different approaches to determine the spatial scale of an environmental area or region that can be impacted by an emitted chemical are investigated. A ranking of chemicals according to the spatial range R on a limited scale, as suggested by Scheringer, is equivalent to the characteristic travel distance L according to Bennett et al. on a linear, open scale. However, the methods are different with respect to the weighting of differences between the chemicals and according to their comparability with persistence. The characteristic travel distance L and the overall persistence are both plotted on open log-linear scales, whereas the spatial range R is represented on a limited scale. Various approaches of how to account for the mode of entry of chemicals are compared, and it is argued that relative measures are more appropriate to describe the long-range transport potential of chemicals than absolute numbers.
Metabolism of the polycyclic aromatic hydrocarbon fluoranthene by the polychaete Capitella capitata species I
Authors: Forbes Valery E , Andreassen Mai S H , Christensen Lene 
Published: March 2010

Abstract
Previous studies have shown that infaunal deposit feeders may enhance the loss of organic contaminants from sediments. However, the extent to which this occurs as a result of sediment microbial stimulation, porewater flushing, or biotransformation by infauna remains unclear. The purpose of this study was to determine whether the infaunal polychaete Capitella sp. I is able to metabolize the polycyclic aromatic hydrocarbon (PAH) fluoranthene and to provide an initial characterization of the metabolites produced. Our results showed that Capitella sp. I is able to metabolize fluoranthene to more hydrophilic products and that, after 24 h in clean sediment, fluoranthene could no longer be detected in worm tissues whereas a number of fluoranthene-derived metabolites were present. None of the metabolites released or retained by worms resembled known bacterial metabolites, suggesting that Capitella, and not bacteria associated with its gut or body surface, were responsible for the biotransformation of fluoranthene in our system. On the basis of ultraviolet maxima, peak shape, relative height, and order of elution, tentative identities of two metabolites (i.e., 3- and 8-hydroxyfluoranthene) are proposed. The results demonstrate that, in addition to their effects on sediment geochemical properties, infaunal polychaetes such as Capitella can enhance the degradation of sediment-associated contaminants by directly metabolizing them.
A large-scale categorization of sites in San Francisco Bay, USA, based on the sediment quality triad, toxicity identification evaluations, and gradient studies
Authors: Hunt John W , Anderson Brian S , Phillips Bryn M , Tjeerdema Ron S , Taberski Karen M , Wilson Craig J , Puckett H Max , Stephenson Mark , Fairey Russell , Oakden James 
Published: March 2010

AbstractSediment quality was assessed in San Francisco Bay, California, USA, using a two-tiered approach in which 111 sites were initially screened for sediment toxicity. Sites exhibiting toxicity were then resampled and analyzed for chemical contamination, recurrent toxicity, and, in some cases, benthic community impacts. Resulting data were compared with newly derived threshold values for each of the metrics in a triad-based weight-of-evidence evaluation. Sediment toxicity test results were compared with tolerance limits derived from reference site data, benthic community data were compared with threshold values for a relative benthic index based on the presence and abundance of pollution-tolerant and -sensitive taxa, and concentrations of chemicals and chemical mixtures were compared with sediment quality guideline-based thresholds. A total of 57 sites exceeded threshold values for at least one metric, and each site was categorized based on triad inferences. Nine sites were found to exhibit recurrent sediment toxicity associated with elevated contaminant concentrations, conditions that met program criteria for regulatory attention. Benthic community impacts were also observed at three of these sites, providing triad evidence of pollution-induced degradation. Multi- and univariate correlations indicated that chemical mixtures, heavy metals, chlordanes, and other organic compounds were associated with measured biological impacts in the Bay. Toxicity identification evaluations indicated that metals were responsible for pore-water toxicity to sea urchin larvae at two sites. Gradient studies indicated that the toxicity tests and benthic community metrics employed in the study predictably tracked concentrations of chemical mixtures in Bay sediments.
Factors affecting reproduction and the importance of adult size on reproductive output of the midgeChironomus tentans
Authors: Sibley Paul K , Ankley Gerald T , Benoit Duane A 
Published: March 2010

AbstractWe conducted two spearate tests to evaluate the influence of several factors that could affect estimation and interpretation of effects on reproductive output of Chironomus tentans in sediment toxicity tests. Specifically, the influence of adult size, mating frequency in males (♂), and age of both males and females (♀) at first mating on mating success (number of successful matings), fecundity (number of eggs/female), percentage hatch, and number of offspring (number of hatched eggs) was assessed. In the first experiment, the influence of adult size on reproductive output was determined by growing midges fed a low (0.29 mg/individual/ d) and a high (0.42 mg/individual/d) amount of food to produce small (S) and large (L) adults, respectively. The adults were then mated in one of four scenarios: S ♂ × S ♀, S♂ × L ♀, L ♂ × S♀, and L ♂ × L ♀. An increase in male weight at a constant female weight had no significant effect on fecundity, whereas an increase in female weight yielded 49.5 and 60.7% increases in fecundity when mated with low- and high-fed males, respectively. Similarly, mean number of offspring (fecundity × percent hatch) increased by 19.8 and 48.3% when male weight was increased and female weight was held constant and by 141.9 and 180.4% when female weight was increased and male weight was held constant. In the second experiment, conducted at a single feeding rate, fecundity increased significantly with an increase in female weight but not male weight. The number of offspring was not significantly influenced by adult weight. The age of males or females at first mating, the frequency with which males were mated (up to seven consecutive days), and the proportion of males successfully mating had no effect on fecundity or number of offspring; however, large increases in variability about mean estimates were observed in some endpoints for older males. These results suggest that adult female size is the most important factor affecting reproductive output in C. tentans, and that enhanced performance of the life-cycle test with respect to all reproductive endpoints might be achieved if males are not mated for more than five consecutive days.
An assessment of the toxicity of phthalate esters to freshwater benthos. 1. Aqueous exposures
Authors: Call Daniel J , Markee Thomas P , Geiger Dianne L , Brooke Larry T , VandeVenter Fred A , Cox Dean A , Genisot Kristen I , Robillard Kenneth A , Gorsuch Joseph W , Parkerton Thomas F , Reiley Mary C , Ankley Gerald T , Mount David R 
Published: March 2010

Abstract
Tests were performed with the freshwater invertebrates Hyalella azteca, Chironomus tentans, and Lumbriculus variegatus to determine the acute toxicity of six phthalate esters, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butylbenzyl phthalate (BBP), di-n-hexyl phthalate (DHP), and di-2-ethylhexyl phthalate (DEHP). It was possible to derive 10-d LC50 (lethal concentration for 50% of the population) values only for the four lower molecular weight esters (DMP, DEP, DBP, and BBP), for which toxicity increased with increasing octanol–water partition coefficient (Kow) and decreasing water solubility. The LC50 values for DMP, DEP, DBP, and BBP were 28.1, 4.21, 0.63, and 0.46 mg/L for H. azteca; 68.2, 31.0, 2.64, and &gt; 1.76 mg/L for C. tentans; and 246, 102, 2.48, and 1.23 mg/L for L. variegatus, respectively. No significant survival reductions were observed when the three species were exposed to either DHP or DEHP at concentrations approximating their water solubilities.
Vitellogenin gene transcription: A relative quantitative exposure indicator of environmental estrogens
Authors: Lattier David L , Gordon Denise A , Burks Douglas J , Toth Gregory P 
Published: March 2010

Abstract
We report the development of a quantifiable exposure indicator for measuring the presence of environmental estrogens in aquatic systems. Synthetic oligonucleotides, designed specifically for the vitellogenin gene (Vg) transcription product, were used in a reverse transcription–polymerase chain reaction (RT-PCR) protocol. This extremely sensitive and rapid method was able to detect vitellogenin gene transcription in male common carp (Cyprinus carpio) injected with 17β-estradiol. Sequence analysis of the induced mRNA product confirmed a vitellogenin gene transcript with homology to rainbow trout and fathead minnow vitellogenin cDNA sequences. Relative levels of vitellogenin gene induction among individuals were quantified by incorporating 18S ribosomal RNA universal primers and Competimers® in a PCR multiplex reaction with primers for vitellogenin. This method is more sensitive than current protocols, such as mortality, visible signs of stress, or other techniques that look for unscheduled gene expression, because it measures the appearance of primary transcripts at the nanogram level. In addition, this procedure does not sacrifice accuracy or reliability, even though the exposure to estrogen is within 1 d. This research will support the construction of regional stressor profiles, thereby providing a method for comparative environmental exposure assessment. It may also provide an in vivo screening method for potential endocrine-disrupting compounds.
Laboratory and field studies on the effect of molinate, clomazone, and thiobencarb on nontarget aquatic invertebrates
Authors: Burdett Ayesha S , Stevens Mark M , Macmillan David L 
Published: March 2010

Abstract
The midge Chironomus tepperi was used in laboratory experiments to assess the relative toxicity of formulated molinate, clomazone, and thiobencarb, three herbicides used in Australian rice crops. Static bioassays were initiated with first-instar larvae at herbicide concentrations between 0.0625 and 2 times the anticipated field concentrations (AFCs) expected from the registered application rates. Adult emergence success, development time, and wing length were used as indices of the effect of each herbicide. Clomazone had no effect on any parameters at concentrations up to 0.288 mg/L (p &gt; 0.05). Molinate significantly increased development time at concentrations equivalent to the AFC (3.6 mg/L) and above (p &lt; 0.05). Thiobencarb reduced emergence success of adult C. tepperi at 0.0625 times the AFC (0.1875 mg/L) as well as decreasing male adult size and increasing development time for males and females at 0.125 times the AFC (p &lt; 0.05). Nontarget effects of the herbicides on aquatic invertebrate communities were assessed in shallow experimental ponds using commercial application rates. One week after treatment, only thiobencarb had a significant effect, suppressing populations of chironomids, calanoids, and cyclopoids (p &lt; 0.05). Four weeks later, all populations had recovered, equaling or exceeding control densities.
Resistance to copper toxicity in populations of the earthworms Lumbricus rubellus and Dendrodrilus rubidus from contaminated mine wastes
Authors: Langdon Caroline J , Piearce Trevor G , Meharg Andrew A , Semple Kirk T 
Published: March 2010

Abstract
Two arsenic and heavy metal—contaminated mine spoil sites, at Carrock Fell, Cumbria, United Kingdom, and Devon Great Consols Mine, Devon, United Kingdom, have been found to support populations of the earthworms Lumbricus rubellus Hoffmeister and Dendrodrilus rubidus (Savigny). Lumbricus rubellus and D. rubidus collected from the Devon site and an uncontaminated site were kept for 28 d in uncontaminated soil and in soil containing 750 mg/kg CuCl2, the state of the specimens being recorded using a semiquantitative assessment of earthworm health (condition index). The condition index remained high for all specimens except those of L. rubellus and D. rubidus from uncontaminated sites, which displayed 100% mortality. Bioavailability of Cu in the soils from one uncontaminated and two contaminated sites and in the uncoutaminated soil treated with CuCl2 was determined using sequential extraction. Soils from Devon Great Consols had the greatest availability of Cu, Carrock Fell the lowest. Total tissue Cu for L. rubellus and D. rubidus from the contaminated sites did not change significantly for each species during the experiment. Total tissue concentrations of Cu for L. rubellus and D. rubidus from uncontaminated sites increased significantly during the first 7 d, after which mortality was 90%, making it impossible to continue the analysis.
Joint action of chemicals in algal toxicity tests: Influence of response level and dose—response regression model
Authors: Christensen Erik R. , Chen Dongxu , Nyholm Niels , Kusk K. Ole 
Published: March 2010

Abstract
The joint toxicity of nonylamine and decylamine and of atrazine and decylamine was evaluated in assays with the green alga Selenastrum capricornutum based on an isobologram method. In this method, curves of constant response, isoboles, are plotted versus concentrations of two toxicants. The response parameter was growth rate based on biomass, and several response levels were used. Dose—response curves were developed for dilution series using fixed ratios between concentrations in toxic units of the compounds. Probit and Weibull dose—response curves were then determined by nonlinear regression. A model for isoboles for partially similar action was used when applicable. The no-effect concentration (NEC or EC0) was estimated based on a newly proposed model containing median effective concentration (EC50) and EC0 as explicit variables. Results show that nonylamine and decylamine are nearly concentration additive at EC50 and EC10 (similarity parameter Λ = 0.70—0.76) and to a lesser extent at ECO. By contrast, the mixtures of atrazine and decylamine show antagonism in that atrazine acts as an antidote to decylamine. The shapes of these isoboles are independent of response level. The EC50 values (mg/L) for chemicals acting singly were 0.090 (nonylamine), 0.039 to 0.044 (decylamine), and 0.225 (atrazine). In order to determine NEC effectively, the level of inhibition must be fairly low, with observed growth rates between 0.6 and 1.0 times the average growth rate of the controls.
Potential nitrification rate as a tool for screening toxicity in metal-contaminated soils
Authors: Smolders Erik , Brans Kris , Coppens Filip , Merckx Roel 
Published: March 2010

Abstract
A potential nitrification rate test (PNR) was used to identify metal toxicity in field-contaminated soils. The test was applied to metal salt–spiked soils, to 27 uncontaminated soils, and to 15 soils that are contaminated by former metal smelting activities. Four agricultural soils (pH 4.5–6.6) were spiked with various rates of CdCl2 (0–200 mg Cd/kg dry wt) or ZnCl2 (0–3,000 mg Cd/kg dry wt) and were equilibrated more than nine months prior to testing. The soil Zn EC50s of the PNR were between 150 and 350 mg Zn/kg dry weight. No continuous decrease of the nitrification with increasing Cd application was observed. The nitrification rate was reduced by between 50 and 80% at the highest Cd application in all soils. The PNRs of 27 uncontaminated soils varied widely (0–21 mg N/kg/d), but most of this variability is explained by soil pH (R2 = 0.77). The PNRs of the 15 contaminated soils were 0 to 44% of the values predicted for an uncontaminated soil at corresponding pH. Significant toxicity in field-contaminated soils was identified if the PNR was outside the 95% prediction interval of the PNR for an uncontaminated soil at corresponding pH and was found in seven soils. These soils contain 160 to 34,000 mg Zn/kg dry weight and 5 to 104 mg Cd/kg dry weight and had a pH &gt;5.7. No toxicity could be detected below pH 5.6, where even a zero PNR value is within the 95% prediction interval of uncontaminated soils. It is concluded that the nitrification is sensitive to metal stress but that its power as a soil bioassay is low because of the high variability of the endpoint between uncontaminated soils. The ecological significance of the assay is discussed.
Combined effects of predatory fish and sublethal pesticide contamination on the behavior and mortality of mayfly nymphs
Authors: Schulz Ralf , Dabrowski James M 
Published: March 2010

Abstract
We evaluated the potential interaction of pesticide effect and predatory fish on behavior and mortality of a stream mayfly. Experiments in laboratory stream microcosms compared the activity, drift, and mortality of Baetis mayfly nymphs in the absence of fish with that in the presence of Cape galaxias (Galaxias zebratus), both species inhabiting the same stream environments in the Western Cape of South Africa. These two predator treatments were combined with exposure either to no pesticide or to 0.2 μg/L of the organophosphate insecticide azinphos-methyl (AZP) or 0.2 μg/L of the pyrethroid insecticide fenvalerate (FV). Such pesticide levels are known from transient spraydrift- or runoff-related pesticide input into running waters. Each of the six combinations was replicated six times as 30-min trials during the day and effects were analyzed using 2 × 2 factorial analysis of variance (ANOVA). A single exposure to either fish or pesticide significantly increased the absolute activity of mayflies, measured as number of animals visible on top of stones, and the absolute mayfly drift in the fish treatment and in the FV treatment but did not increase the mortality above 0.8%. The combination of predator presence and sublethal pesticide exposure resulted in a significant increase in the mortality rate, to about 9% in the AZP × fish and 25% in the FV × fish treatment, although the activity and drift rates were not increased compared with the single-stressor treatments. Two-by-two factorial ANOVA and the comparison of expected and measured responses indicated that the mortality resulted from a synergistic interaction of the two stressors. The observed mortality was without exception caused by predation of the fish on drifting mayflies. The relative drift rate in the FV × fish treatment was decreased, again due to a synergistic interaction, which suggests an active drift avoidance reaction of the mayflies exposed to the combined pesticide × fish treatment, in contrast with those exposed just to FV. We conclude that the drift response of mayflies to transient sublethal pesticide exposure results in a synergistically increased adverse effect in the presence of predatory fish.
Synthesis and characterization of metal sulfide clusters for toxicological studies
Authors: Bowles Karl C. , Bell Russell A. , Ernste Michael J. , Kramer James R. , Manolopoulos Helen , Ogden Nancy 
Published: March 2010

Abstract
Zinc sulfide clusters were synthesized and characterized at low micromolar concentrations to assess the effect of metal-sulfide ligands on metal toxicity to aquatic organisms in oxic environments. Recommended preparation times are greater than 2 h initial reaction of equimolar sodium sulfide and zinc nitrate, followed by oxic aeration for 3 d. Ionic strength, pH, and anoxic stabilization time were found to be relatively unimportant in controlling the final yield. Adsorptive losses of zinc sulfide (ZnS) clusters to surfaces, however, were significant for a variety of vessel materials and membrane filters. Ionic strength and pH were found to be important factors controlling the extent of adsorptive losses with minimal loss for pHs greater than 9 and for soft waters. The Ag(I), Cu(II), and Hg(II) as metal sulfides completely suppress the analysis of sulfide, whereas Pb(II), Mn(II), and Co(II) partially suppress the analysis of sulfide by the methylene blue technique. Ultraviolet and fluorescence spectra are shown for synthesized ZnS clusters.
The chemical toxic benzo[a]pyrene perturbs the physical organization of phosphatidylcholine membranes
Authors: Jiménez María , Aranda Francisco J. , Teruel J. Antonio , Ortiz Antonio 
Published: March 2010

Abstract
The interaction of the chemical carcinogen benzo[a]pyrene (BaP) with phosphatidylcholine membranes has been investigated by using various physical techniques. Differential scanning calorimetry showed that BaP, at concentrations as low as 2 mol% in mixtures with dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine, and distearoylphosphatidylcholine, abolished the pretransition and broadened and shifted to lower temperatures the main gel-to-liquid crystalline phase transition. The effect was stronger as the lipid acyl chain length decreased. Infrared spectroscopy indicated that inclusion of BaP had a strong influence on the carbonyl (C=O) stretching band. Fitting of this band resulted in the presence of three components in the case of samples containing BaP, centered at 1,742, 1,727, and 1,704 cm−1 (only two components, at 1,742 and 1,727 cm−1, were observed for pure DMPC). The component at 1,704 cm−1 corresponded to a disolvate and strongly supported the notion that inclusion of BaP increases hydration of the bilayer C=O. Small-angle x-ray diffraction showed that incorporation of 10 mol% BaP into DMPC increased bilayer thickness from 66.7 to 71 A in the gel state and from 58.9 to 60.9 A in the fluid phase. It is proposed that, when BaP is incorporated into a phospholipid bilayer, it locates in the most apolar region of the phospholipid palisade, resulting in expansion and swelling of the membrane. These two effects will facilitate water penetration into the polar region of the membrane, as observed by the increased hydration of the C=O groups, and thus perturb both membrane integrity and functionality.