bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection of optimal measures of growth and reproduction for the sublethal Leptocheirus plumulosus sediment bioassay
Authors: Gray Brian R , Emery Vallen L , Brandon Dennis L , Wright Rachel B , Duke B Maurice , Farrar J Daniel , Moore David W 
Published: March 2010

Abstract
This article describes the selection process used to identify optimal measures of growth and reproduction for the proposed 28-d sublethal sediment bioassay with the estuarine amphipod Leptocheirus plumulosus. We used four criteria (relevance of each measure to its respective endpoint, signal-to-noise ratio, redundancy relative to other measures of the same endpoint, and cost [i.e., of labor, training, and equipment]) to evaluate nine growth and seven reproductive measures. Optimal endpoint measures were identified as those receiving relatively high scores for all or most criteria. Measures of growth scored similarly on all criteria, except for cost. The cost of the pooled (female plus male) growth measures was substantially lower than the cost of the female and male growth measures because the latter required more labor (by approx. 25 min per replicate). Pooled dry weight was identified as the optimal growth measure over pooled length because the latter required additional labor and nonstandard software and equipment. Embryo and neonate measures of reproduction exhibited wide differences in labor costs but yielded similar scores for other criteria. In contrast, brooding measures of reproduction (females carrying embryos in the brood pouch) scored relatively low on endpoint relevance, signal-to-noise ratio, and redundancy criteria. We recommend neonates/survivor as the optimal measure of L. plumulosus reproduction because it exhibited high endpoint relevance and signal-to-noise ratios, was redundant to other reproductive measures, and required minimal time.
Relation of lead exposure to sediment ingestion in mute swans on the Chesapeake Bay, USA
Authors: Beyer W Nelson , Day Daniel , Morton Anna , Pachepsky Yakov 
Published: March 2010

Abstract
Although wildlife risk assessments are generally based on the accumulation of environmental contaminants through food chains, wildlife may also ingest contaminants incidentally with sediment. Forty-two mute swans (Cygnus olor) were collected from unpolluted portions of central Chesapeake Bay, Maryland, USA, in spring 1995, and their intestinal digesta were analyzed for 13 metals (aluminum [Al], boron, barium, cadmium, copper [Cu], iron, magnesium, manganese, nickel, lead [Pb], strontium, vanadium, and zinc) and for acid-insoluble ash, a marker of sediment. Swan livers and sediment samples also were analyzed for the same metals. Group method of data handling demonstrated that the digesta Al, which is associated with clays, was the best predictor of digesta Pb. Adding concentrations of other metals as predictors did not improve the accuracy of the estimates of Pb concentrations from Al concentrations. The r2 of the equation relating the log of digesta Pb to the log of digesta Al was 0.86, whereas the r2 of the equation relating the log of digesta Pb to the log of digesta acid-insoluble ash was 0.50. Accounting for the sediment ingested was critical to determining the exposure of mute swans to Pb, as well as to some of the other metals, and sediment ingestion should be considered in ecotoxicological risk assessments of waterfowl. The mean of 7.4% acid-insoluble ash in the digesta corresponded to an estimated 3.2% sediment in the diet. The Pb concentrations in the digesta were two to three times the concentration that would have been predicted from sediment Pb concentrations; presumably, the swans had ingested clays high in Pb that had settled on the vegetation. The swans were probably not exposed to high Cu concentrations but nevertheless had hepatic Cu concentrations that would be considered very high if found in other species.
Model for trace metal exposure in filter-feeding flamingos at Alkaline Rift Valley Lake, Kenya
Authors: Nelson Yarrow M , Thampy Ramesh J , Motelin Gideon K , Raini Jackson A , DiSante Cynthia J , Lion Leonard W 
Published: March 2010

Abstract
Toxic trace metals have been implicated as a potential cause of recent flamingo kills at Lake Nakuru, Kenya. Chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) have accumulated in the lake sediments as a result of unregulated discharges and because this alkaline lake has no natural outlet. Lesser flamingos (Phoeniconaias minor) at Lake Nakuru feed predominantly on the cyanobacterium Spirulina platensis, and because of their filter-feeding mechanism, they are susceptible to exposure to particle-bound metals. Trace metal adsorption isotherms to lake sediments and S. platensis were obtained under simulated lake conditions, and a mathematical model was developed to predict metal exposure via filter feeding based on predicted trace metal phase distributions. Metal adsorption to suspended solids followed the trend Pb ≫ Zn &gt; Cr &gt; Cu, and isotherms were linear up to 60 μg/L. Adsorption to S. platensis cells followed the trend Pb ≫ Zn &gt; Cu &gt; Cr and fit Langmuir isotherms for Cr, Cu and Zn and a linear isotherm for Pb. Predicted phase distributions indicated that Cr and Pb in Lake Nakuru are predominantly associated with suspended solids, whereas Cu and Zn are distributed more evenly between the dissolved phase and particulate phases of both S. platensis and suspended solids. Based on established flamingo feeding rates and particle size selection, predicted Cr and Pb exposure occurs predominantly through ingestion of suspended solids, whereas Cu and Zn exposure occurs through ingestion of both suspended solids and S. platensis. For the lake conditions at the time of sampling (1.2 g/L suspended solids, 0.23 g/L S. platensis), predicted ingestion rates based on measured metal concentrations in lake suspended solids were 0.71, 6.2, 0.81, and 13 mg/kg-d for Cr, Cu, Pb, and Zn, respectively. Higher exposure doses are predicted when metal concentrations are determined from sediment concentrations rather than suspended solids concentrations. Also, decreases in the S. platensis population would increase the clearing rate of the flamingos and increase predicted metal exposure via ingestion of suspended solids. For example, with metal concentrations calculated based on average metal concentrations in lake sediments and S. platensis concentration of 0.06 g/L, exposure rates would be 13, 10, 4.4, and 38 mg/kg-d for Cr, Cu, Pb, and Zn, respectively. These ingestion rates, except for Cu, are significantly higher than the no observable adverse effects levels.
Chronic retene exposure causes sustained induction of CYP1A activity and protein in rainbow trout (Oncorhynchus mykiss)
Authors: Fragoso Nuno M , Parrott Joanne L , Hahn Mark E , Hodson Peter V 
Published: March 2010

AbstractThe removal of persistent chlorinated organic compounds from pulp mill effluents has not eliminated mixed function oxygenase (MFO) induction by these effluents. Therefore, continuous MFO induction downstream of pulp mills may be due to exposure to more labile compounds, such as retene (an alkyl-substituted phenanthrene), which typically cause transient induction after a single brief exposure. Because fish are exposed continuously to pulp mill effluents, we have tested, and rejected, the null hypothesis that continuous exposure of fish to retene does not cause sustained MFO induction. Rainbow trout exposed continuously to retene, a component of some pulp mill effluents and sediments downstream of pulp mills, showed concentration-dependent increases in hepatic ethoxyresorufin-O-deethylase (EROD) activity. The increase in EROD activity was sustained over 32 d of continuous exposure, but it diminished to background levels within 4 d after transfer to clean water. The enzymatic response was confirmed by measuring changes in the content of immunodetectable cytochrome P4501A (CYP1A) protein. These data support a role for labile, nonhalogenated compounds in chronic effects of pulp mill effluents on fish.
Species selection for an ecological risk assessment of the Columbia River at the Hanford Site, Washington, USA
Authors: Becker James , Brandt Charles , Dauble Dennis 
Published: March 2010

Abstract
We describe a two-tier screening methodology used to select receptor species for an ecological risk assessment of the Columbia River at the Hanford Site in south-central Washington state. This approach was developed and implemented under the guidance of the Columbia River Comprehensive Impact Assessment Management Team (CRCIA Team), a public steering committee comprised of members of regulatory agencies, native American tribes, and other stakeholders. Three hundred sixty-eight species that occur in the riverine and riparian communities of the Columbia River were reduced to 52 using criteria identified by an independent panel of biologists (tier I) and by scoring and ranking species based on their potential exposure to contaminated media (tier II). This two-tier screening methodology could be implemented at other locations where the number of species present must be reduced for an ecological risk assessment and where receptor species with relatively high potential contaminant exposures need to be evaluated. Participation of the CRCIA Team in the species selection process facilitated agreement between risk assessors, regulators, and stakeholders as to the number and kinds of organisms to be evaluated in our risk assessment. It is critical that regulators and stakeholders be involved in the selection of receptors to ensure that species of public interest as well as ecologically relevant species are evaluated in ecological risk assessments. This approach will increase the likelihood that such risk assessments will be used in management decisions.
Distribution and composition of polycyclic aromatic hydrocarbons within experimental microcosms treated with creosote-impregnated Douglas fir pilings
Authors: Bestari K T Jim , Robinson Richard D , Solomon Keith R , Steele Tracey S , Day Kristen E , Sibley Paul K 
Published: March 2010

AbstractTemporal changes in the concentration and relative composition of 15 priority polycyclic aromatic hydrocarbons (PAHs) in water, sediment, and polyvinylchloride (PVC) strips were assessed to evaluate the fate of creosote leached from impregnated wood pilings in aquatic environments. The study consisted of single microcosms containing one of 0.5, 1, 2, 3, 4, or 6 creosote-impregnated pilings and two microcosms containing untreated pilings. Quantitative analyses of PAHs were performed using high-performance liquid chromatography equipped with a fluorescence detector. For each treatment, total PAHs(∑ PAH) in water increased rapidly up to 7 d posttreatment yielding a clear dose-dependant concentration gradient ranging from 7.3 (0.5 pilings) to 97.2 μg/L (6 pilings). Total PAHs declined exponentially after 7 d and was reduced close to background concentrations (0.8–6.7 μg/L) by the end of the study (84 d). No increase in ∑ PAH was observed in sediments at any treatment, nor was there any relationship between sediment PAHs and distance from each piling cluster. However, a slight increase in PAHs was observed on PVC liner strips that exhibited a concentration gradient similar to that in water. The PVC-bound ∑ PAH ranged from 0.3 to 2.4 μg/cm2 and 0.2 to 2.2 μg/cm2 at 31 and 58 d posttreatment, respectively. Based on these data, we estimated a rate loss of creosote from the pilings of approximately 50 μg/cm2/d (273 mg/piling/d). The low concentration of PAHs on the PVC, along with the absence of accumulation of PAHs in sediments, suggests that creosote was lost primarily from water via degradative pathways such as photolysis and microbial decomposition and adsorption onto PVC. The rapid loss of creosote from water in conjunction with the slow rate of leaching from the pilings suggests that risks associated with the use of creosote-impregnated pilings in aquatic environments may be minimal.
Effect of wetting and drying on the bioavailability of organic compounds sequestered in soil
Authors: White Jason C , Quiñones-Rivera Antonio , Alexander Martin 
Published: March 2010

Abstract
A study was conducted to determine whether cycles of wetting and drying alter the availability of organic compounds that have aged in soil. Subjecting soil to wetting-and-drying cycles during periods of aging &lt;60 d decreased the biodegradability, extractability, and uptake by earthworms of phenanthrene and reduced the extractability of di(2-ethylhexyl) phthalate (DEHP) sequestered in soil compared with soil aged at constant moisture. The mineralization of sequestered DEHP was greater in soil that was wet and dried during a 41-d period of aging than in soil incubated at constant moisture. Wetting and drying soil during periods of aging of 100 or more days had no effect on the biodegradability or assimilation by Eisenia foetida of sequestered phenanthrene and DEHP. Subjecting soil containing previously sequestered phenanthrene to one, three, or four wetting-and-drying cycles increased the biodegradability of the compound. The extractability of sequestered phenanthrene was greater in soil that was wet and dried once after aging than in soil maintained at constant moisture, but three wetting-and-drying cycles did not affect extractability. The biodegradability of sequestered DEHP was unaffected by wetting and drying. We suggest that wetting and drying may be useful in the remediation of contaminated soils.
Investigation of naphthalene sorption in soils and soil fractions using batch and column assays
Authors: Bayard Rémy , Barna Ligia , Mahjoub Borhane , Gourdon Rémy 
Published: March 2010

Abstract
The adsorption–desorption of naphthalene on several soil fractions and model soils has been studied in batch and column experiments to investigate the complementarity between the two methods. Batch experiments, in which the sorbents were suspended in aqueous solutions of naphthalene at different initial concentrations, were used to determine the states of apparent equilibrium and approach the kinetics of adsorption and desorption. Apparent equilibrium was reached in batch within 10 to 15 h and could be described with simple linear isotherms in the ranges of concentrations studied. A significant fraction of naphthalene was found to be adsorbed almost instantaneously, the rest being adsorbed more progressively, following first-order kinetics. Adsorption of naphthalene mainly takes place on the organic matter of the soils or soil fractions. Adsorption is directly related to the organic content of the soil fractions and not to the size of the particles with which the organic matter is associated. Naphthalene adsorption was found to be well reversible when the pollutant–sorbent contact time was short (24 h) and the sorbed concentration was relatively low. At higher sorbed concentrations, a slight hysteresis effect was observed in batch studies. Data obtained from soil column experiments conducted with water as mobile phase were in good agreement with the results obtained in batch. The adsorption was described using a double-compartment model, considering a nonuniform distribution of the adsorption sites (organic matter) between the external surface of soil microaggregates (with instantaneous adsorption) and the internal compartment inside the microaggregates (with rate-limited adsorption). The site distribution depends on the nature and degree of humification of the soil organic matter.
Effects of pentachlorophenol on survival of earthworms (Lumbricus terrestris) and phagocytosis by their immunoactive coelomocytes
Authors: Giggleman Marina A , Fitzpatrick Lloyd C , Goven Arthur J , Venables Barney J 
Published: March 2010

Abstract
Earthworms, Lumbricus terrestris, exposed for 96 h to filter paper saturated with five nominal concentrations of pentachlorophenol (PCP: 5–50 μg PCP/cm2), exhibited a 50% lethal concentration (LC50) of 25.0 μg PCP/cm2 (95% confidence interval [CI]: 22.8–27.2) and corresponding whole worm body burden-based 50% lethal dose (LD50) of 877.7 μg PCP/g dry mass (95% CI: 828.5–927.0). Linear regression modeling showed that worms increased body concentrations (BC = μg PCP/g dry tissue mass) with increasing exposure concentrations (EC) according to BC = 113.5 + 29.5EC (r2 = 0.94, p = 0.03). Phagocytosis of yeast cells by immunoactive coelomocytes was suppressed only at body concentrations (863.3 μg PCP/g dry mass) that approximated the calculated LD50 and overlapped those demonstrating lethality, indicating a sharp transition between sublethal and lethal toxicity. An exposure concentration of 15 μg PCP/cm2 produced significant suppression of phagocytosis of yeast cells by immunoactive coelomocytes. However, the average measured body burden from this group (863.3 μg PCP/g dry mass) approximated the estimated LD50, indicating a sharp toxic response slope. Exposure to 10 μg PCP/cm2 with a corresponding body concentration of 501.3 μg PCP/g dry mass did not affect phagocytosis. The importance of body burden data is emphasized.
Influence of nutrient additions on cadmium bioaccumulation by aquatic invertebrates in littoral enclosures
Authors: Currie Robert S , Muir Derek C G , Fairchild Wayne L , Holoka Morris H , Hecky Robert E 
Published: March 2010

AbstractCadmium distribution and bioaccumulation were examined over a 2-year period (1991–1992) in two nutrient-enriched and two control littoral enclosures and in the littoral zone in Lake 382 (L382). Lake 382, a small oligotrophic lake, is located within the Experimental Lakes Area in northwestern Ontario, Canada, and received experimental Cd additions from 1987 to 1992. In the second year of this study, chlorophyll a and suspended C concentrations in the nutrient-enriched enclosures increased by 6.6 and 3.4 times, respectively, compared to the controls. As a result of increased particulate produced by the nutrient additions, Cd concentrations in water from the nutrient-enriched enclosures were higher (46–114 ng/L) compared to the controls (23–84 ng/ L). Estimated Cd/C concentrations in water were lower in the nutrient-enriched enclosures relative to the controls because of higher particle concentrations. Effects on Cd bioaccumulation were limited even though mesotrophic to eutrophic conditions were reached in the nutrient-enriched enclosures. Trends for lower Cd concentrations in mussels and crayfish from the nutrient-enriched enclosures compared to the controls were observed; however, significant differences were rarely detected. Zooplankton and immature Chironomidae from the nutrient-enriched enclosures had consistently higher Cd concentrations compared to the controls, but significant differences were not detected. Enhanced accumulation of Cd-rich particulate matter by these organisms may account for this trend. Mussels and crayfish accumulated significantly more Cd when exposed in the lake compared to the enclosures. This observation is due to elevated Cd water concentrations in the lake compared to the enclosures because of continued Cd additions to the lake. These results suggest that the water route of exposure is an important pathway for Cd accumulation by these organisms.
Relative role of pore water versus ingested sediment in bioavailability of organic contaminants in marine sediments
Authors: Forbes Thomas L , Forbes Valery E , Giessing Anders , Hansen Rikke , Kure Liv K 
Published: March 2010

Abstract
Experimental data for fluoranthene and feeding selectivity in combination with reaction-diffusion modeling suggest that ingestion of contaminated sediment may often be the dominant uptake pathway for deposit-feeding invertebrates in sediments. A dietary absorption efficiency of 56% and accompanying forage ratio of 2.4 were measured using natural sediment that had been dual-labeled (14C:51Cr) with fluoranthene and fed to the marine deposit-feeding polychaete Capitella species I. Only 3 to 4% of the total absorption could be accounted for by desorption during gut passage. These data were then used as input into a reaction-diffusion model to calculate the importance of uptake from ingested sediment relative to pore-water exposure. The calculations predict a fluoranthene dietary uptake flux that is 20 to 30 times greater than that due to pore water. Factors that act to modify or control the formation of local chemical gradients, boundary layers, or dietary absorption rates including particle selection or burrow construction will be important in determining the relative importance of potential exposure pathways. From a chemical perspective, the kinetics of the adsorption and desorption process are especially important as they will strongly influence the boundary layer immediately surrounding burrowing animals or irrigated tubes. The most important biological factors likely include irrigation behavior and burrow density and size.
Copper toxicity to the endoparasitic trematode (Posthodiplostomum minimum) relative to physid snail and bluegill sunfish intermediate hosts
Authors: Soucek David J , Noblet Gayle P 
Published: March 2010

Abstract
A laboratory study was conducted to determine copper toxicity to the endoparasitict ematode Posthodiplostomum minimum (MacCallum) relative to snail first intermediate hosts and bluegills (Lepomis macrochirus Rafinesque) as second intermediate hosts. To determine copper effects on cercariae, the life-cycle stages of P. minimum were established in the laboratory. A 96-h median lethal concentration (LC50) test for bluegills was performed, and the calculated value of 0.892 mg/L total Cu was considered in selection of copper concentrations for all other experiments. Snail hosts (Physella gyrina (Say)) exposed to copper concentrations equal to 0, 8.9, 22.3, 44.6, and 89.2 μg/L Cu, exhibited a significant toxic response with ∼64% and ∼87% mortality occurring in the 44.6 and 89.2 μg/L concentrations, respectively. The 7-d LC50 for snails was 38.0 μg/L Cu. Free-swimming cercariae exposed to the same copper concentrations exhibited a similar toxic response with a 9-h LC50 of 32.0 μg/L Cu and a 12-h LC50 of 26.0 μg/L Cu.
Seasonal variations in susceptibility of Apis mellifera to the synergistic action of prochloraz and deltamethrin
Authors: Meled Maggy , Thrasyvoulou Andreas , Belzunces Luc P 
Published: March 2010

Abstract
The synergistic action of prochloraz and deltamethrin was investigated in summerand winter bees. Prochloraz and deltamethrin were used at sublethal doses that did not induce any significant mortality. Bees were treated with different doses of deltamethrin, either alone or in combination with prochloraz, at the constant field rate of 25 g/ha. In summer bees, the combination of prochloraz and deltamethrin at 125 mg/ha triggered a synergy that produced approx. 63 ± 5% mortality (corrected) after 24 h. At 62.5 mg/ha, deltamethrin still acted in synergy with prochloraz by inducing about 32.5 ± 3.5% mortality (corrected) after 24 h. The field rate of 31.25 mg/ha was the lowest dose at which deltamethrin acted in synergy with prochloraz in summer bees. In winter bees, no synergy occurred between prochloraz and deltamethrin at doses of 125 and 250 mg/ha. The deltamethrin dose had to be increased to 500 mg/ha to observe a synergy that produced only 47 ± 11.7% mortality (corrected) after 24 h. Considering the deltamethrin doses at which synergy occurred, summer bees appeared to be approximately eightfold more susceptible than winter bees to the synergistic action of prochloraz and deltamethrin.