bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of arsenic speciation and low dissolved oxygen condition on the toxicity of arsenic to a lotic mayfly
Authors: Irving Elaine C , Lowell Richard B , Culp Joseph M , Liber Karsten , Xie Qianli , Kerrich Robert 
Published: February 2008

AbstractThe influence of site-specific conditions on contaminant bioavailability and toxicity to benthic invertebrates is a key consideration in the environmental risk assessment process. This is particularly relevant for contaminants with complex speciation chemistries, such as arsenic. The present study addressed uncertainties regarding arsenic toxicity to a mayfly (Baetis tricaudatus) under low dissolved oxygen (DO) conditions characteristic of many contaminated sites. Arsenic toxicity (arsenite, As(III); arsenate, As(V)) to mayfly nymphs was assessed under two DO scenarios (68 and 84% saturation). Arsenic speciation ratios were determined during testing to confirm the nature of arsenic exposure. The present study found that As(III) was more lethal and bioaccumulated to a greater degree in B. tricaudatus compared to As(V), but the sublethal toxicities of the two arsenic species were similar. Nymph growth and development were significantly inhibited after 12 d of exposure to both 1 mg/L of As(III) and As(V). Exposure to arsenic under low DO conditions (6.5 mg/L, 68% saturation) did not significantly affect As(III) or As(V) toxicity and bioaccumulation over 12 d. The DO level of 6.5 mg/L, however, appeared to be marginally lethal to B. tricaudatus. Results indicate that the Canadian arsenic criterion for the protection of aquatic life (5 μg/L) is protective of B. tricaudatus and is low enough to accommodate differences in arsenic toxicity because of the interconversions between As(III) and As(V). These findings provide insight regarding the toxicity and speciation of arsenic under DO conditions considered to be low for this lotic mayfly species and representative of existing conditions at mine sites in northern Canada.
Cadmium, iron, and zinc uptake individually and as a mixture by Limnodrillus hoffmeisteri and impact on adenosine triphosphate content
Authors: Ortega Ma de los Angeles Grajeda y , López Eugenia López , Perotzi Liliana Favari , Garduño-Siciliano Leticia , Martínez Marcela Galar 
Published: February 2008

Abstract
Heavy metals, such as Fe, Zn, and Cd, are major pollutants in aquatic ecosystems. These toxicants usually are present in these ecosystems in the form of mixtures, and their effect on exposed organisms is the result of interactions occurring between the metals as well as with other pollutants and environmental factors. The present study evaluated the uptake of Cd, Fe, and Zn individually and as a mixture and their effect on adenosine triphosphate (ATP) content in Limnodrillus hoffmeisteri, an important aquatic organism given its resistance to large amounts of these xenobiotics. Test organisms were exposed for 96 h to sediment treated with each of these metals individually and as a mixture. The metal concentrations used were equivalent to the zero lethal concentration of these pollutants as determined in a previous study. At the end of the exposure period, metal concentration in medium and organism as well as ATP content in the latter were quantified. Metal uptake was measured by determining the bioconcentration factor at 96 h. All three metals elicited an important decrease in ATP content when acting singly and as part of a mixture. When present as a mixture, their uptake and effect on L. hoffmeisteri are modified. Therefore, a joint-action toxicity approach should be used for toxicity evaluations involving these pollutants.
Dose-dependent uptake, elimination, and toxicity of monosodium methanearsonate in adult zebra finches (Taeniopygia guttata)
Authors: Albert Courtney A , Williams Tony D , Morrissey Christy A , W.M.-Lai Vivian , Cullen William R , Elliott John E 
Published: February 2008

Abstract
Monosodium methanearsonate (MSMA), an arsenic-based pesticide, has been used for the past 10 years in attempts to suppress mountain pine beetle (Dendroctonus ponderosae) outbreaks in British Columbia, Canada. Previous studies have shown that cavity nesting forest birds such as woodpeckers forage and breed in MSMA treated pine stands. Here we examined the effects of MSMA in the laboratory using the zebra finch (Taeniopygia guttata), with the objective to examine tissue distribution and sublethal toxic effects in a model avian species. Zebra finches were exposed to this pesticide at doses similar to those found in bark beetle samples from MSMA stands of trees treated in the southern interior of British Columbia (8, 24, and 72 μg/g/d and a control group). Results showed high excretion (&gt;90%) of arsenic in all dose groups, as well as dose-dependent trends in accumulation of arsenic in the blood (p &lt; 0.001) and specific tissues. Monomethylarsonic acid, MMA (V), was the predominant form of arsenic in the blood plasma. Dimethylarsinic acid was the major form of arsenic found in the liver (83%) and kidney (61%) tissues. The brain tissue contained primarily the MMA (V) form (57%). Significant weight loss occurred in the two highest dose groups (p &lt; 0.05). Birds in the highest dose group lost up to 15% of initial body mass.
Alteration of leaf decomposition in copper-contaminated freshwater mesocosms
Authors: Roussel Helene , Chauvet Eric , Bonzom Jean-Marc 
Published: February 2008

AbstractThe influence of copper on leaf litter decomposition was examined in experimental streams. Controls and three levels of contamination (5, 25, and 75 μg/L) were tested in triplicate in 20-m-long mesocosms. Equal quantities of alder, maple, and oak leaves were enclosed in mesh bags and placed in the upper and lower mesocosm sections that exhibited different habitat characteristics (shallow with pebble substrate or deep with fine substrate and macrophytes, respectively). Decomposition rate in the upper section of the 75 μg/L mesocosms was significantly reduced to 28% of control values. No significant reductions in the decomposition rate were seen in the lower section. No differences in the leaf-associated mycelial biomass and sporulation rates were observed between treatments, but they were consistently higher in the upper sections. The aquatic hyphomycete community was not affected by the contamination. The abundances of total leaf-associated macroinvertebrates and the dominant shredder (Gammarus pulex) were considerably reduced in the upper sections at 75 μg/L. Therefore, the reduced leaf decomposition probably resulted from a reduction in the abundance of macroinvertebrate detritivores. In addition, local variations in physical and biological characteristics of the habitat along the mesocosms significantly influenced the effects of copper on leaf-associated decomposers.
Behavior of Corophium volutator (Crustacea, Amphipoda) exposed to the water-accommodated fraction of oil in water and sediment
Authors: Kienle Cornelia , Gerhardt Almut 
Published: February 2008

Abstract
We investigated the short-term effects of the water accommodated fraction (WAF) of weathered Forties crude oil on the behavior of Corophium volutator in the Multispecies Freshwater Biomonitor® (MFB). When exposing C. volutator to 25 and 50% WAF in aqueous exposures, hyperactivity with an additional increase in ventilation was detected, whereas exposure to 100% WAF led to hypoactivity (narcosis). In a sediment exposure with 100% WAF, there was an increased tendency toward hyperactivity. In a pulse experiment, hyperactivity appeared at and after a 130-min exposure to 50% WAF in a majority of cases. Our experiments suggest that the behavior of C. volutator as measured in the MFB may be an appropriate parameter for coastal monitoring.
DNA microarray application in ecotoxicology: Experimental design, microarray scanning, and factors affecting transcriptional profiles in a small fish species
Authors: Wang Rong-Lin , Biales Adam , Bencic David , Lattier David , Kostich Mitch , Villeneuve Dan , Ankley Gerald T , Lazorchak Jim , Toth Greg 
Published: February 2008

AbstractThe research presented here is part of a larger study of the molecular mode of action of endocrine-disrupting chemicals targeting the hypothalamic–pituitary–gonadal axis in zebrafish (Danio rerio). It addresses several issues critical to microarray application in aquatic ecotoxicology: experimental design, microarray scanning, gene expression intensity distribution, and the effect of experimental parameters on the zebrafish transcriptome. Expression profiles from various tissues of individual zebrafish exposed to 17α-ethinylestradiol (30 ng/L), fadrozole (25 μg/L), or 17β-trenbolone (3.0 μg/L) for 48 or 96 h were examined with the Agilent Oligo Microarray (G2518A). As a flexible and efficient alternative to the designs commonly used in microarray studies, an unbalanced incomplete block design was found to be well suited for this work, as evidenced by high data reproducibility, low microarray-to-microarray variability, and little gene-specific dye bias. Random scanner noise had little effect on data reproducibility. A low-level, slightly variable Cyanine 3 (Cy3) contaminant was revealed by hyperspectral imaging, suggesting fluorescence contamination as a potential contributor to the large variance associated with weakly expressed genes. Expression intensities of zebrafish genes were skewed toward the lower end of their distribution range, and more weakly expressed genes tended to have larger variances. Tissue type, followed in descending order by gender, chemical treatment, and exposure duration, had the greatest effect on the overall gene expression profiles, a finding potentially critical to experimental design optimization. Overall, congruence was excellent between quantitative polymerase chain reaction results and microarray profiles of 13 genes examined across a subset of 20 pairs of ovarian samples. These findings will help to improve applications of microarrays in future ecotoxicological studies.
Trace element and metallothionein concentrations in seabirds from the Canadian Arctic
Authors: Braune Birgit M , Scheuhammer Anton M 
Published: February 2008

Abstract
Livers and kidneys were collected for five seabird species from the Canadian Arctic during the 1983 and 1991 to 1993 breeding seasons. Livers were analyzed for Cd, Hg, Pb, and Se, and kidneys were analyzed for Cd, Cu, Zn, and metallothionein (MT). Concentrations of the essential elements, Cu and Zn, were in agreement with those previously published in the literature. Thick-billed murres (Uria lomvia) from Ivujivik on the Hudson Strait/Hudson Bay coast in northwestern Quebec (Canada) had the highest mean renal concentrations of Cu, Zn, and Cd. Among the four species collected from Prince Leopold Island, northern fulmars (Fulmarus glacialis) had the highest hepatic concentrations of both Cd and Hg. The highest Se concentrations were found in northern fulmars and black-legged kittiwakes (Rissa tridactyla) from Prince Leopold Island. Hepatic Pb concentrations were low (&lt;0.3 μg/g dry wt) in all species at all locations. Metallothionein concentrations were positively correlated with Cd and Zn for all species combined but were not correlated with Cu in any species. No significant relationships were found between MT and Cu or Zn in black guillemots (Cepphus grylle) or glaucous gulls (Larus hyperboreus). To our knowledge, this is the first report of MT concentrations and their relationships with trace metals in Arctic seabirds.
Chronic exposure to low concentrations of waterborne cadmium during embryonic and larval development results in the long-term hindrance of antipredator behavior in zebrafish
Authors: Kusch Robin C , Krone Patrick H , Chivers Douglas P 
Published: February 2008

AbstractCadmium has been recognized for some time as a potent environmental pollutant with the capability of disrupting olfactory-mediated behaviors. Failing to respond to chemical cues in the environment could adversely affect foraging, reproduction and predator avoidance. Recognizing this impaired perception as a serious ecological problem has been undermined by the fact that the damage is often reversible; short depuration periods of 5 d may allow for the re-establishment of responses to chemical cues. In this experiment, early life stage zebrafish were continuously exposed for 50 d at 0, 0.2, 2.0, and 20 μg Cd/L. The subjects were depurated for 14 d and then subjected to behavioral testing where antipredator responses to chemical alarm cues were observed. Our data show that continuous exposure during rearing to a concentration as low as 20 μg Cd/L is sufficient at eliminating antipredator behavior in zebrafish (Danio rerio) even after the source of the cadmium had been removed for 14 d. Furthermore, subjects raised under a 10-fold lower concentration also showed alteration in their behavioral responses, taking significantly longer to respond to the predation threat. Exposure to low levels of cadmium throughout development may alter neurogenesis, subsequently resulting in long-term impairment of chemical cue perception.
Metals affect soil bacterial and fungal functional diversity differently
Authors: Stefanowicz Anna M , Niklińska Maria , Laskowski Ryszard 
Published: February 2008

Abstract
Heavy metals can cause a decrease in the taxonomic diversity of soil communities. Because of functional redundancy, it remains unclear to what extent different functions performed by the soil microbial communities may be affected by pollution. We studied the impact of metal contamination on soil bacterial and fungal functional diversity, active microbial biomass, and soil respiration rate. Soil samples were collected from 39 sites along three forest and five meadow pollution transects near an abandoned Pb/Zn smelter in Avonmouth (UK) and Ni smelter in Clydach (UK), in a Cu mining and smelting region near Glogow (Poland), and in a Zn/Pb mining and smelting region near Olkusz (Poland). Biolog® GN2 and SFN2 plates were used to study the bacterial and fungal functional diversity, which subsequently was expressed as Shannon's diversity index (H′). The active microbial biomass was measured as substrate-induced respiration. We found that the bacterial functional diversity significantly decreased, whereas the fungal functional diversity slightly increased, with increasing metal concentration. We also observed a slight negative effect of metal pollution on the active microbial biomass. No relationship was found between metal contamination and total soil respiration rate. This suggests a higher sensitivity of bacterial functional diversity as an indicator for the effects of metal pollution compared with overall soil respiration. All microbial parameters were affected by nutrient concentrations and/or soil pH.
Mixture toxicity and gene inductions: Can we predict the outcome?
Authors: Dardenne Freddy , Nobels Ingrid , de Coen Wim , Blust Ronny 
Published: February 2008

Abstract
As a consequence of the nature of most real-life exposure scenarios, the last decade of ecotoxicological research has seen increasing interest in the assessment of mixture ecotoxicology. Often, mixtures are considered to follow one of two models, concentration addition (CA) or response addition (RA), both of which have been described in the literature. Nevertheless, mixtures that deviate from either or both models exist; they typically exhibit phenomena like synergism, ratio or concentration dependency, or inhibition. Moreover, both CA and RA have been challenged and evaluated mainly for acute responses at relatively high levels of biological organization (e.g., whole-organism mortality), and applicability to genetic responses has not received much attention. Genetic responses are considered to be the primary reaction in case of toxicant exposure and carry valuable mechanistic information. Effects at the gene-expression level are at the heart of the mode of action by toxicants and mixtures. The ability to predict mixture responses at this primary response level is an important asset in predicting and understanding mixture effects at different levels of biological organization. The present study evaluated the applicability of mixture models to stress gene inductions in Escherichia coli employing model toxicants with known modes of action in binary combinations. The results showed that even if the maximum of the dose–response curve is not known, making a classical ECx (concentration causing x% effect) approach impossible, mixture models can predict responses to the binary mixtures based on the single-toxicant response curves. In most cases, the mode of action of the toxicants does not determine the optimal choice of model (i.e., CA, RA, or a deviation thereof).
Effect of copper complexation on the estrogenic activities of endocrine-disrupting compounds using E-screen bioassay
Authors: Park Jong Yol , Lee Byoung Cheun , Ra Jin Sung , Lee Jiho , Kim Sang Don 
Published: February 2008

Abstract
The complexation reaction between Cu and four targeted endocrine-disrupting compounds (EDCs)—17β-estradiol (E2), 17α-ethynylestradiol (EE2), 4-octylphenol (OP), and bisphenol A (BPA)—was studied using the fluorescence quenching method, with the changed EDC forms evaluated for their estrogenic activities using an E-screen assay. The results of the E-screen showed no estrogenic activity of Cu, whereas results with the EDCs indicated high cell proliferation (decreasing order of induction: E2, EE2, OP, and BPA). The results of the fluorescence quenching response and FTIR (Fourier transformation infrared) strongly support the formation of Cu complexes on the –OH functional group of the targeted EDCs when Cu was spiked at concentrations between 10−7 and 10−4 M. The degree of complexation was in the following order: E2, EE2, OP, and BPA. The E-screen result for three of the EDCs, with the exception of BPA, was similar when estimating the effects of Cu on the estrogenic activities of the EDCs, which were significantly reduced at α = 0.05 with increasing Cu concentration. Consequently, the results of the complexation reaction and E-screen assay with the Cu-EDC mixtures indicated that Cu plays a significant role in the assessment of the estrogenic activities of EDCs in natural waters.
Temporal and spatial variation in solar radiation and photo-enhanced toxicity risks of spilled oil in Prince William Sound, Alaska, USA
Authors: Barron Mace G , Vivian Deborah , Yee Susan H , Diamond Steve A 
Published: February 2008

Abstract
Solar irradiance (W/m2) and downwelling diffuse attenuation coefficients (Kd; 1/m) were determined in several locations in Prince William Sound (AK, USA) between April 2003 and December 2005 to assess temporal and spatial variation in solar radiation and the risks of photo-enhanced toxicity from spilled oil. Weekly irradiance measurements of surface visible light, ultraviolet B (UVB), and ultraviolet A (UVA) radiation in Valdez (AK, USA) followed expected trends of maximum solar irradiance at each summer solstice and minimum values at each winter solstice. Variation from weekly maximum expected surface irradiances was attributed to large variations in environmental conditions over the 142-week monitoring period. Season and proximity to glacial meltwater were significant determinants of Kd, with 1% attenuation depths ranging from 0.4 to 15 m (UVB and UVA) and from 0.5 to 28 m (visible light). The probability of photo-enhanced toxicity risks estimated from UVA dosimetry decreased with increasing water depth, with higher risks during spring and summer and lower risks during fall and winter. These results demonstrate substantial temporal and spatial variation in solar radiation in Prince William Sound and the potential for significant season- and location-specific photo-enhanced toxicity risks from spilled oil.
Survival rates and blood metal concentrations in two species of free-ranging North American sea ducks
Authors: Wayland Mark , Drake Kiel L , Alisauskas Ray T , Kellett Dana K , Traylor Joshua , Swoboda Cindy , Mehl Katherine 
Published: February 2008

Abstract
Populations of several species of North American sea ducks have declined in the past few decades. Exposure to environmental contaminants, particularly metals, has been proposed as one of many possible factors contributing to these declines. Population dynamics are influenced by survival rates and breeding effort. In the present study, we examined the relationships between blood metal concentrations (Cd, Pb, Se, and Hg) and apparent annual survival and recapture probabilities (the latter as a surrogate for breeding effort) in adult females of two sea duck species, the king eider (Somateria spectabilis) and the white-winged scoter (Melanitta fusca), both of which have experienced declines in continental population during in recent years. No support was found for the hypothesis that exposure of white-winged scoters to these metals or of king eiders to Cd, Se, and Pb adversely affected probabilities of apparent annual survival. We detected a weak negative relationship ( = −0.833) between Hg and annual survival of king eiders, but the 90% confidence interval of the slope estimate overlapped zero (-2.439 to +0.672). Recapture probabilities were unrelated to concentrations of Cd, Se, and Pb in either species. Evidence indicated that Hg concentrations affected recapture probability in white-winged scoters ( = —194.77; 90% confidence interval, −203.770 to −185.778). Mercury levels were low in both species, and blood samples may not adequately represent long-term exposure to Hg. Therefore, conclusions regarding Hg effects on these birds should be considered with caution.
Ranking of agricultural pesticides in the rhine-meuse-scheldt basin based on toxic pressure in marine ecosystems
Authors: Jong Irmgard Henning-de , van Zelm Rosalie , Huijbregts Mark A.J , de Zwart Dick , van der Linden Ton M.A , Wintersen Arjen , Posthuma Leo , van de Meent Dik 
Published: February 2008

AbstractAlthough risk assessments on a per-chemical basis are required during the registration procedure of pesticides, cumulative risks from the use of all pesticides on the variety of crops in a catchment area of a river are not assessed. The present study aimed to rank pesticides used in outdoor agricultural practice within the catchment of the rivers Rhine, Meuse, and Scheldt according to their potential toxic impact on the North Sea coastal ecosystem. Toxic pressure calculations (based on steady-state concentrations calculated with a multimedia fate model) and species-sensitivity distribution–based risk estimations were performed for pesticide emissions in the years 1998 (189 pesticides) and 2004 (133 pesticides). A ranking was established according to the relative contribution of single pesticides and crop types to the overall toxic pressure. Calculations were performed probabilistically to deal with parameter uncertainties. Only a few pesticides and crop types dominate overall toxic pressure because of emissions in both years, and the uncertainty appears to be caused largely by uncertainties in interspecies variances of aquatic toxicities. For 1998, these pesticides were fentin-acetate, with a median relative contribution (RCx) to the toxic pressure of multiple chemicals on an ecosystem of 0.43. For 2004, the pesticides that contributed most were pencycuron and paraquat-dichloride, with a median RCx of 4.4 × 10−2 and 3.9 × 10−2, respectively. Pesticides applied to potato cropland and fruit trees contributed most to the overall toxic pressure.