bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mercury-induced micronuclei in skin fibroblasts of beluga whales
Authors: Gauthier Julie M , Dubeau Hélène , Rassart Éric 
Published: March 2010

AbstractBeluga whales (Delphinapterus leucas) inhabiting the St. Lawrence estuary are highly contaminated with environmental pollutants and have a high incidence of cancer. Environmental contaminants may be partly responsible for the high incidence of cancer observed in this population. DNA damage plays an important role in the development of cancer. The micronuclei assay was used to test the genotoxic potential of mercury compounds in skin fibroblasts of an Arctic beluga whale. Both mercuric chloride (Hg) and methylmercury (MeHg) induced a highly significant (p &lt; 0.001) dose–response increase of micronucleated cells. Statistically significant increases in micronucleated cells were observed for 0.5, 5, and 20 μg/ml Hg and 0.05, 0.5, and 2 μg/ml MeHg when compared to control cultures. Concentrations of 0.5, 5, and 20 μg/ml Hg induced a two-, three- and fourfold increase of micronucleated cells, respectively. Treatment with MeHg was one order of magnitude more potent in inducing micronuclei and in inhibiting cell proliferation than Hg. Although results of this in vitro study do not imply that mercury compounds are involved in the etiology of cancer in St. Lawrence beluga whales, significant increases in micronuclei frequency were found at low concentrations of MeHg (0.05 and 0.5 μg/ml) that are believed to be comparable to concentrations present in certain whales of this population.
Selenium accumulation in captive american kestrels (Falco sparverius) fed selenomethionine and naturally incorporated selenium
Authors: Yamamoto Julie T , Santolo Gary M , Wilson Barry W 
Published: March 2010

Abstract
Male–female pairs of kestrels were maintained for 11 weeks on diets containing 5 or 9 ppm selenium (Se) (dry weight) as seleno-L-methionine, or naturally incorporated Se in the form of mammals collected at Kesterson Reservoir, CA, USA. Selenium concentrations in blood and excreta of male and female kestrels within groups were similar. Near-maximal mean Se concentrations in blood were observed after the 5th week of treatment in the seleno-L-methionine-treated kestrels, and an approximately 1:1 ratio was observed between maximal blood concentrations and dietary concentrations. All treatment groups exhibited reduction of Se concentration in excreta, but not in blood, to baseline values 4 weeks after treatment ended. No birds were observed to exhibit signs of general illness or Se toxicity during the study.
Combined effects of dissolved organic material and water hardness on toxicity of cadmium to Daphnia magna
Authors: Penttinen Sari , Kostamo Auli , Kukkonen Jussi V K 
Published: March 2010

Abstract
The interaction between dissolved organic material (DOM) and water hardness and their effects on the acute toxicity of cadmium (Cd) to Daphnia magna was studied. At an original hardness (0.1 mmol Ca + Mg per liter) of humic lake water (DOC 19.6 mg/L), Cd was significantly less toxic in the humic than in the reference (DOC &lt; 0.2 mg/L) water. Furthermore, after dilution down to 10% (dissolved organic carbon [DOC] 2.0 mg/L), the humic water still decreased the lethality significantly. The results suggest that the reduced toxicity of Cd in the lake water is due to complexation with DOC. An increase in water hardness (from 0.1 to 0.5 or 2.5 mmol Ca + Mg per liter) decreased the measured binding coefficient of Cd to DOM. In addition, the acute toxicity of Cd decreased, and the difference between the reference and humic water disappeared. As a conclusion, DOM in the soft lake water had a protective effect against Cd toxicity. In hard water, obviously, the added hardness cations, especially Ca2+, effectively competed with Cd2+ for available binding sites in DOM. Simultaneously, Ca2+ ions interfered also with the uptake of Cd2+ either by competing in transport through cell membranes or by reducing membrane permeability.
Assessment of various biomarkers in winter flounder from coastal Massachusetts, USA
Authors: Wall Kristen L , Jessen-Eller Kathy , Crivello Joseph F 
Published: March 2010

AbstractSince 1992, the Massachusetts Water Resource Association has organized a Fish Day to assess the health of winter flounder in Boston Harbor and nearby areas. This report describes the levels of metal contaminants and selected biomarkers in flounder from Fish Day, 1996. Mean age for males and females was 3.5 years, which is lower than the age reported for fish collected during previous efforts. Body weight/body length ratios were significantly higher in females versus males. Liver Cd, As, Zn, and Cu, and muscle As were all elevated relative to U.S. Environmental Protection Agency designations for marine fish liver and muscle tissue in all animals from all sites. Male flounder from Boston Harbor had significantly higher liver Cd levels than female flounder from Cape Cod and Boston Harbor. Female flounder from Boston Harbor showed significantly less metallothionein (MT) protein and lower liver metal levels than those from Cape Cod. Metallothionein mRNA did not significantly differ between sites nor did MT protein or mRNA between males and females from Boston Harbor. Cytochrome P450 2E1 (CYP2E1)-like and CYP1A1 activities were significantly higher at optimal temperatures than activity measured at field temperatures. No differences between groups were observed for either parameter at ambient temperatures, but at optimal temperature(s), Boston Harbor females had significantly higher CYP2E1-like and CYP1A1 activities than Boston Harbor males. A negative correlation was found between maximal CYP1A1 activity and age for the Boston Harbor fish and a positive correlation for all fish between CYP2E1-like activity at ambient temperature and percent liver lipid. No differences were observed for liver lipid and microsomal protein between any of the groups. Liver glycogen showed a sex-dependent difference for the Boston Harbor group with levels in females significantly higher than males. These differences in contaminant levels and biomarkers are discussed within the context of data from previous Fish Days and the implications for flounder health within Boston Harbor.
Structural chemistry and geochemistry of silver-sulfur compounds: Critical review
Authors: Bell Russell A , Kramer James R 
Published: March 2010

Abstract
Silver(I) bindss srongly with sulfur(II –) in inorganic and organic species, resulting in picomolal aqueous dissolved concentrations. For sulfur species found in the environment, Ag(I)–S(II) bonding forms a linear di-coordinate arrangement, – S–Ag–S–, which results in long zigzag chains in inorganic (minerals) and organic (thiolate) complexes. Silver(I) forms the neutral complex AgHS0 at low concentration of S(II –) and Ag(I). Polynuclear complexes form in solution above micromolal concentrations of S(II –). Silver(I) polysulfides may be significant at elevated S(II –). A number of organic mercaptans (thiols) are found in anoxic sediments in nanomolal to micromolal levels and these can act as ligands for Ag(I). The surprisingly limited, known properties of Ag(I) complexes (thiolates) of environmental mercaptans are reviewed. In these thiolate complexes in the solid phase, single crystal X-ray diffraction shows that the –S(R)–Ag –S(R)– chains condense to form sheets that further link through silver–silver interactions to create a network, or slab of silver and sulfur atoms. From nuclear magnetic resonance spectroscopic evidence, zigzag chains also form in the solution phase and aggregate in a random manner to form colloids, which are the predominant form of Ag(I) in solution. The most crucial and important aspect of Ag(I) thiolate chemistry is the rapid exchange of Ag(I) among thiolates. This process is a mechanism whereby Ag(I) can transfer onto, or off, particulate materials or the cells of an organism. Silver(I) thiolates also react rapidly with H2S or HS− as ligands to form Ag2S, but the reverse process is poor because of the high aqueous insolubility and stability of A2Ss. This reaction represents a possible final fate for any Ag(I) thiolate formed in natural waters, as well as any Ag(I)–S(II –) species.
Silver at an old mining camp, Cobalt, Ontario, Canada
Authors: Kramer James R , Adams Nicholas W H , Manolopoulos Helen , Collins Pamela V 
Published: March 2010

AbstractAueous Ag(I) in different sze f actions, &lt;5 μm, &lt;0.2 μm, and &lt;10 kDa, was analyzed in a low dissolved organic carbon (DOC) and a high DOC environment. The sediment and tailings, contacting the water, were elevated in silver (10–100 mg/kg) from mining. The area is buffered at pH 6 to 8 by carbonate mineral gangue. Aqueous Ag(I) is present at nanogram per liter levels. Significant amounts of Ag are found in the colloidal (0.2 μm to 10 kDa) and are nondetectable (&lt;0.3 ng/L) or a few nanograms per liter in the &lt;10-kDa fraction. Acid-volatile sulfide (AVS) was found in most (oxic) water samples at the nanomolar level. Ag(I) does not accumulate in plants probably due to the strong binding of Ag(I–) with S(II–). One exception occurs for cattails, when the aqueous AVS concentration is less than the colloidal Ag(I) concentration.
Silver toxicity toChironomus tentansin two freshwater sediments
Authors: Call Daniel J , Polkinghorne Christine N , Markee Thomas P , Brooke Larry T , Geiger Dianne L , Gorsuch Joseph W , Robillard Kenneth A 
Published: March 2010

AbstractSediment collected from two freshwater lakes, West Bearskin Lake(Cook, MN, USA) and Bond Lake (Douglas, WI, USA), was characterized for grain size, total organic carbon, (TOC), acid-volatile sulfides (AVS), simultaneously extracted metals (SEM), and iron (Fe). Both sediments had low levels of TOC (&lt;1.0 percent) and AVS (&lt;1.1 μmol/g). West Bearskin Lake sediment contained more small (silt and clay) particles than Bond Lake, which was 95% sand. West Bearskin Lake also had higher SEM (σ SEM = 0.815 vs 0.074 μmol/g) and had an Fe content that was approximately 30-fold greater than that of Bond Lake. These sediments were amended with AgNO3 in a series of concentrations, some of which were intended to exceed the total silver (Ag)-binding capacity of the sediments, allowing for the appearance of dissolved Ag in pore water (PW). Sediment toxicity tests were then designed such that the AgNO3 amendment levels would result in PW concentrations that bracketed the 10-d concentration causing 50% lethality (LC50) for dissolved Ag of 0.057 mg/L, as determined in a toxicity test in water alone (i.e., without sediment present). The 10-d LC50 values for Chironomus tentans, based upon nominal additions of Ag to the sediments, were 2.75 and 1.17 g Ag per kilogram dry sediment for West Bearskin and Bond Lake sediments, respectively. An LC50 value based upon dissolved Ag in the PW was determined only for Bond Lake sediment and was approximately 275 times greater than the water-only LC50 value. This indicated that a high proportion of the dissolved fraction was not readily bioavailable to cause lethality. A reduction in PW pH and the displacement of other metals from sediment into PW with Ag additions to the sediment likely contributed to the observed mortalities and weight losses, particularly at the higher exposure levels. The concentrations of Ag in these sediments that resulted in biological effects are considerably higher than levels reported in the environment.
Principal response curves: Analysis of time-dependent multivariate responses of biological community to stress
Authors: Van den Brink Paul J , Braak Cajo J F Ter 
Published: March 2010

AbstractIn this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)–pH–alkalinity–conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
Community level analysis of ecotoxicological field studies: II. Replicated-design studies
Authors: Kedwards Timothy J , Maund Stephen J , Chapman Peter F 
Published: March 2010

Abstract
Conventional statistical methods of analyzing large-scale ecotoxicological field studies have centered around the use of univariate procedures, such as analysis of variance (ANOVA) and t testing. Although such techniques are well documented and robust, the measures produced reflect differences at the individual rather than the community level. Because such techniques permit only small subsets of the collated data to be analyzed at any one time, many analyses must be performed and interpreted. Multivariate analysis provides a viable and complementary alternative whereby a single analysis can incorporate all collated data and provide graphical and statistical measures of changes in community structure. In this study, the ordination techniques of redundancy analysis (RDA) and principal response curve (PRC) analysis were used to evaluate macroinvertebrate community responses to two pyrethroid insecticides in a replicated aquatic mesocosm. Observed changes in community structure between control and treated mesocosms were evaluated statistically using a before-after-control-impact (BACI) design Monte Carlo permutation test. Cypermethrin and lambda-cyhalothrin were applied at similar activity rates of 0.7 and 0.17 g active ingredients (a.i.)/ha, respectively. No significant effect was observed on the macroinvertebrate community, measured in emergence traps, for either pyrethroid at any rate. A significant change from the control community structure due to 0.7 g a.i./ha cypermethrin and 1.7 g a.i./ha lambda-cyhalothrin application was identified in the macroinvertebrate communities in artificial substrate samples, principally due to a decline in Gammaridae and Asellidae. The Asellidae population that was treated with cypermethrin recovered fully toward the end of the study period. The capability of multivariate techniques to draw out trends at a major community level within a large data matrix, combined with their increased ecological relevance compared to studies at lower levels of biological organization, makes them powerful analytical tools. Increased integration of multivariate techniques into regulatory assessments is likely to improve the value and efficiency of ecotoxicological field studies for ecological risk assessment.
Quantitative structure–activity relationship of a series of N-Aryl O-Aryl phosphoramidate insecticides
Authors: Ali Hussein M , Mostafa Azza A 
Published: March 2010

Abstract
A series of O-ethyl O-aryl N-aryl phosphoramidates was prepared and examined for housefly contact toxicity and acetylcholinesterase (AChE) inhibition. Results showed a moderate toxicity and enzyme inhibition effect. These biological properties correlated to Hammett sigma constants in the direction of increasing activity with increasing electron donation of the substituents on either the phenolic or anilinic ring of the phosphoramidates. These correlations suggest the formation of a positive charge on the phosphorus atom that is stabilized by electron-donating groups. This result invokes the mechanism of the electropholic attack of phosphorus on a nucleophilic center of AChE. The moderate toxicity of phosphoramidates is attributed to the reduction of the positive charge on the phosphorus atom by the effect of the neighboring nitrogen atom during the course of the enzyme-inhibitor interaction and hence decreasing the inhibition effect. Mass spectra of these compounds are also discussed in some detail.
Confirmation of elemental sulfur toxicity in the Microtox® assay during organic extracts assessment of freshwater sediments
Authors: Pardos Michel , Benninghoff Christophe , Thomas Richard L , Khim-Heang Sophal 
Published: March 2010

AbstractRecent literature indicates that the elemental sulfur occurring in organic extracts of sediment samples can be toxic to the bacterium Vibrio fischeri, used in standard Microtox® bioassays. This observation was tested by means of the solvent extraction of 14 freshwater sediment samples from rivers tributary to Lake Geneva (Switzerland–France), measuring both Microtox toxicity and the elemental sulfur concentration of the extracts. Aliquots of these sediment extracts were further treated to remove the sulfur by adding acid-activated copper to the crude extracts; for 18 h in one case, and for 116 h in an other. The results were a significant amount of the observed acute toxicity in the Microtox assay of 81% of sample extracts (n = 42, crude and after cleanup) was due to elemental sulfur, and despite a median decrease of 99.1% of elemental sulfur in the extracts subject to a 116-h cleanup, sulfur toxicity was not completely excluded for 57% (8/14) of the samples. Clearly, the Microtox methodology needs to be amended to more accurately assess the potential impact of organic pollutants in sediments when solvent extracts are used. This will help to cut down on costly and unnecessary remedial actions.
In vitro and in vivo acetylcholinesterase-inhibiting effect of new classes of organophosphorus compounds
Authors: Ozmen Murat , Sener Sadiye , Mete Ahmet , Kucukbay Hasan 
Published: March 2010

Abstract
Anticholinesterase properties of 14 new synthesized organophosphorus (OP) compounds and four of their starting substances were tested in vitro and in vivo using electric eel acetylcholinesterase (AChE) and Rana ridibunda (frog of lowland) tadpoles, respectively. Gusathion-M® was used as a reference anti-AChE agent. Acetylcholinesterase inhibition capacity of tested compounds was assayed for 30-min period in vitro studies using electric eel AChE, of which 14 OP compounds inhibited enzyme activity more than 50% within 30 min, excluding Gusathion-M. However, four of the compounds inhibited AChE less than 50% during the test period. On the other hand, 12 of the OPs did not bring about mortality, whereas six of the tested compounds were found to be lethal agents for R. ridibunda tadpoles, for which values of concentration causing 50% lethality ranged from 14.42 to 89.95 ppm. Also, the highest degree of enzyme inhibition occurred by diethyl chlorophosphate (ETCP), which inhibited AChE activity 62% at 2.89 ppm in 24-h toxicity tests and which was more effective than Gusathion-M. The lethal OP compounds represented good correlation between dose and enzyme-inhibition capability in in vivo tests, but only ETCP showed such a relation for anti-AChE effect in both in vitro and in vivo conditions.
Sensitivity and variability of metrics used in biological assessments of running waters
Authors: Carlisle Daren M , Clements William H 
Published: March 2010

AbstractWe evaluated the variability and sensitivity of a suite of biological metrics for detecting the ecological effects of metals in streams. The variability of these metrics was evaluated by partitioning the total variance in a three-way analysis of variance among spatial, seasonal, annual, and temporal–spatial interaction components using data from 6 years of biomonitoring on the Arkansas River, Colorado, USA. We then calculated the statistical power of these metrics given a likely experimental design aimed at detecting metal-pollution effects in streams and using estimates of variability from field data. Finally, we experimentally tested the sensitivity of these metrics to a metal mixture in stream microcosms. More than one half of the variation in richness and scraper functional feeding group metrics was explained by differences among sampling sites, which were presumably due to the presence of metal pollution. Statistical power was highest for richness measures and low for all other metrics examined. Experimental exposures revealed that richness measures were also more sensitive than functional group metrics. Our results support those of previous, comparative studies that show the superiority (in terms of sensitivity, variability, and statistical power) of taxa richness measures. Most abundance, ratio, and functional group metrics were either insensitive to metal pollution, highly variable, or both. We conclude that similar systematic testing on a variety of metrics with other stressors will greatly enhance the utility of biological metrics in assessing the ecological effects of contaminants and establishing biological criteria.
Benthic invertebrate metals exposure, accumulation, and community-level effects downstream from a hard-rock mine site
Authors: Beltman Douglas J , Clements William H , Lipton Joshua , Cacela David 
Published: March 2010

Abstract
This study quantitatively evaluated the relationships among As, Co, and Cu concentrations in exposure media (surface water, sediment, and aufwuchs), As, Co, and Cu concentrations in aquatic macroinvertebrates, and invertebrate community structure in a mine-affected stream. Concentrations of As, Co, and Cu were significantly elevated in both exposure media and invertebrate tissue downstream from the mine. Copper in invertebrates was significantly correlated only with Cu in aufwuchs, and Co in invertebrates was significantly correlated only with dissolved Co in water, suggesting different mechanisms of invertebrate accumulation for these two metals. The invertebrate community was severely affected downstream from the mine, with a loss of metalssensitive species and reductions in both total biomass and number of species. Total abundance was not affected. Principal components analysis was performed on the invertebrate community data to develop a simplified description of community response to mine inputs. Based on this index, metal concentrations in invertebrates were poor predictors of community structure. Copper concentrations in water, combined with an estimate of invertebrate drift from clean tributaries, were statistically significant predictors of community structure.