bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution and composition of polycyclic aromatic hydrocarbons within experimental microcosms treated with liquid creosote
Authors: Bestari K T Jim , Robinson Richard D , Solomon Keith R , Steele Tracey S , Day Kristen E , Sibley Paul K
Published: March 2010

Temporal changes in the distribution and relative composition of 15 priority polycyclic aromatic hydrocarbons (PAHs) in water, sediment, and absorbed to polyvinylchloride (PVC) strips were assessed following direct application of liquid creosote to aquatic microcosms. Fourteen microcosms were treated with nominal creosote concentrations ranging from 0.06 to 109 mg/L and two microcosms served as controls. Quantitative analysis of PAHs was performed using high-performance liquid chromatography equipped with a fluorescence detector. Post-treatment concentration of PAHs in water decreased exponentially with time. At 2 d posttreatment, total PAHs (∑ PAH) ranged from 7.3 μg/L (lowest treatment) to 5,803.2 μg/L (highest treatment); by 84 d, ∑ PAH in the same microcosms was reduced to between 0.8 μg/L and 13.9 μg/L, respectively. The relative composition of PAHs in the water also changed with time; at 2 d posttreatment, ∑ PAH in the lowest treatment (7.3 μg/L) reflected contribution from nine PAHs, whereas only two PAHs contributed to this concentration (0.8 μg/L) at 84 d. Low and high molecular weight (mol. wt.) PAHs were lost first from the water column, followed by PAHs of intermediate mol wt. In sediments, a dose-dependent increase in ∑ PAH was observed above 0.59 mg/L creosote up to 28 d, followed by a decline thereafter in all but the highest treatment. Total PAHs in sediment ranged from 0.91 μg/g (lowest treatment) to 63.9 μg/g (highest treatment) at 28 d. A dose-dependent relationship was also observed in PVC strips, with ∑ PAH on PVC ranging from 0.05 to 88 μg/cm2 at 31 d and 0.04 to 18.4 μg/cm2 at 58 d posttreatment. A mass balance evaluation showed that 88.3% of PAHs was lost from the system after 1 month, indicating that liquid creosote is attenuated relatively quickly in aquatic environments.
Physiologically based toxicokinetic model for maternal transfer of 2,3,7,8-tetrachlorodibenzo-p-dioxin in brook trout (Salvelinus fontinalis)
Authors: Nichols John W , Jensen Kathleen M , Tietge Joseph E , Johnson Rodney D
Published: March 2010

A physiologically based toxicokinetic (PB-TK) model was developed to describe the uptake, distribution, and elimination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in female brook trout during a 6-month feeding and depuration study. Dietary uptake was modeled under two assumptions, uptake proceeds to equilibrium between blood exiting the intestinal tract and the contents of the intestinal tract, and uptake is limited by desorption of TCDD from gut contents and/or diffusion from the lumen into tissues. Model outputs were evaluated by comparison with measured TCDD residues. The best model fit to the data was obtained by imposing a moderate diffusion limitation on gut uptake. Of the parameters that comprise the gut submodel, whole body residue predictions were most sensitive to changes in the diffusion rate constant and fecal egestion rate. Chemical residues in fat were indicative of an internal disequilibrium with other tissues during the loading phase of the study. Accurate simulations of this behavior were obtained using a diffusion-limited tissue description. Chemical residues in liver, muscle, and ovaries were adequately described by assuming that uptake and elimination were blood flow limited. Spawning probably resulted in a small increase in whole body TCDD concentration and did not appear to represent an important route of chemical elimination. These results suggest that field-derived whole body TCDD residues could be used to estimate residues in developing ovaries of brook trout to within a factor of two, provided that whole body and ovary lipid content were known.
Metal and phytochelatin content in phytoplankton from freshwater lakes with different metal concentrations
Authors: Knauer Katja , Ahner Beth , Xue Han Bin , Sigg Laura
Published: March 2010

The tace metal (Cu, Zn, Cd, Mn) and phytochelatin(an intracellular chelator for metal ions) cellular content were determined in phytoplankton samples originating from four lakes (Greifen, Sempach, Lucerne, and Orta). The lakes differ in their metal concentrations and in other conditions (pH, trophic state, organic matter). Total and intracellular contents of Cu and Cd were related to the experimentally determined free metal ion concentration and the total and intracellular content of Mn to the dissolved Mn. The intracellular Zn content was tightly regulated over a broad range of [Zn2+]. Phytochelatin concentrations were measurable in phytoplankton communities from three of the lakes, in spite of low levels of free Cu, Zn, and Cd ion concentrations. Culture experiments showed that the concentration of intracellular phytochelatin in Scenedesmus subspicatus and in a natural algal community increased upon addition of copper in a similar concentration range as in the lakes. Phytochelatin concentrations were below detection in the phytoplankton collected from the highly contaminated Lake Orta, perhaps suggesting that this algal community has adapted in some other way to high metal concentrations. Although we only sampled a few lakes, the lack of any clear relationship between phytochelatin and metal concentrations calls into question the feasibility of using phytochelatins as a bioindicator of metal exposure in lakes.
Biota–sediment accumulation and trophic transfer factors for extremely hydrophobic polychlorinated biphenyls
Authors: Maruya Keith A , Lee Richard F
Published: March 2010

Polychlorinated biphenyls (PCBs) in fish, invertebrates, and sediment from a contaminated tidal creek system in coastal Georgia (USA) were traced to Aroclor 1268, a mixture of hepta through decachlorinated homologs (x̄CI = 8.5) used at a former chlor/alkali plant adjacent to the study site. The base 10 logarithm of the octanol/water partition coefficient (Kow) for the 15 most abundant Aroclor 1268 components in these samples ranged from 6.7 to >9. The composite mean biota–sediment accumulation factor (BSAF) for these congeners was 3.1, 0.81, and 0.28 for yearling striped mullet, spotted sea trout, and grass shrimp, respectively, species representing three trophic levels of the local food web. Individual congener BSAFs were negatively correlated (p ≤ 0.05) with log Kow for all three species. The composite mean trophic transfer factor (TTFlip), defined as the ratio of lipid-normalized PCB concentrations in fish to grass shrimp, was higher for mullet (12) than for sea trout (2.9). Individual TTFlip values were two to three times higher for Cl7 and Cl8 homologs that were substituted at all four ortho positions, suggesting a difference in PCB retention based on chlorine substitution patterns. The relative magnitude of BSAFs and TTFlip values indicated that sediment-ingesting forage species like mullet efficiently accumulate PCBs and are an important link in the food web transfer of sediment-associated contaminants in this system. The negative linear relationships between BSAF and log Kow established in this study are among the first to be reported in the field for extremely hydrophobic PCBs.
Nondestructive indicator of ethoxyresorufin-O-deethylase activity in embryonic fish
Authors: Nacci Diane , Coiro Laura , Kuhn Anne , Champlin Denise , Munns Wayne , Specker Jennifer , Cooper Keith
Published: March 2010

Many environmental contaminants of concern produce aryl hydrocarbon (Ah) receptor-mediated effects often assessed as ethoxyresorufin-O-deethylase (EROD) activity. We modified a standardized embryonic and larval fish bioassay using an estuarine fish species (Fundulus heteroclitus) to include measurement of fluorescence in the urinary bladders of living embryos as a nondestructive indicator of EROD activity. This fluorescence was observed only in embryos exposed to the EROD substrate and Ah receptor agonists and was consistent in fluorescence characteristics with the EROD product, resorufin. Aryl hydrocarbon receptor-agonist exposures at sublethal concentrations in the parts per billion range, produced significant increases in EROD fluorescence in embryos as young as 3 d postfertilization. These findings are consistent with the conclusion that this fluorescence method is a specific and sensitive nondestructive indicator of Ah receptor-mediated effects in an embryonic fish. As such, this simple method may be useful for assessing effects of environmental contaminants on the early development of fishes and to link molecular indicators with organism-level responses.
Mercury-induced micronuclei in skin fibroblasts of beluga whales
Authors: Gauthier Julie M , Dubeau Hélène , Rassart Éric
Published: March 2010

Beluga 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 < 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

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

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 < 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

Since 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

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

Aueous Ag(I) in different sze f actions, <5 μm, <0.2 μm, and <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 (<0.3 ng/L) or a few nanograms per liter in the <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

Sediment 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 (<1.0 percent) and AVS (<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

In 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

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

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

Recent 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

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

We 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

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.
Photoinduced toxicity of fluoranthene to northern leopard frogs (Rana pipiens)
Authors: Monson Philip D , Call Daniel J , Cox Dean A , Liber Karsten , Ankley Gerald T
Published: March 2010

Rana pipiens larvae (96–118 h old) were exposed for 48 h in a flow-through system to clean water or five concentrations (0.89, 2.18, 6.99, 12.0, and 30.6 μg/L) of the phototoxic polycyclic aromatic hydrocarbon (PAH) fluoranthene. Following this uptake period, the larvae were divided into four groups: one for immediate tissue residue analysis, a second for residue analysis following 48 h of depuration in clean water, and two for a 48-h exposure in clean water to ultraviolet (UV) light at two different levels. At the highest treatment, mean (±SD) UVA (310–390 nm) intensity was 8.12 ± 0.19 × 102 μW/cm2, whereas at a lower treatment the UVA intensity was 4.45 ± 0.05 × 102 μW/cm2. Larval frogs bioaccumulated fluoranthene in direct proportion to the water exposure concentrations, with initial whole-body PAH concentrations of 1.48, 3.53, 4.85, 11.3, and 18.7 μg/g at the five treatment levels. No mortality of the animals occurred during the 48-h uptake phase. When the frogs were placed in clean water, the fluoranthene was rapidly depurated, with up to 80% lost in 48 h. Exposure to UV light following fluoranthene exposure significantly enhanced toxicity of the PAH. Median time to death decreased as the product of UVA light intensity and fluoranthene body residue increased. For larval R. pipiens, sufficient tissue residues of fluoranthene were bioaccumulated within 48 h, at water exposure concentrations in the range of 2 to 10 μg/L, to be lethal when combined with a UVA exposure simulating a fraction of summertime, midday sunlight in northern latitudes.
Comparison between the effects of the phytosterol β-Sitosterol and pulp and paper mill effluents on sexually immature rainbow trout
Authors: Tremblay Louis , Kraak Glen Van Der
Published: March 2010

Smaller gonads, delayed sexual maturity and depression of sex steroids have been reported in fish exposed to pulp and paper mill effluents. β-Sitosterol, a phytosterol present in pulp and paper mill effluents that causes reductions in sex steroid secretion in fish, may contribute to some of these effects. In this study, the effects of 17β-estradiol (E2), β-sitosterol from two sources, and two Canadian bleached mill effluents (BME) on sexually immature rainbow trout were investigated in a 21-d in vivo experiment. Both β-sitosterol sources and the two BMEs exerted similar effects. Plasma vitellogenin levels were elevated by all treatments establishing the presence of estrogenic compounds in BME and confirming the estrogenicity of β-sitosterol. β-Sitosterol and BME had little or no effect on testosterone levels. Pregnenolone was significantly reduced by β-sitosterol and BMEs but not by E2, suggesting that this was not an estrogenic effect. Plasma cholesterol was reduced by β-sitosterol but not by BME or E2. Feral female white sucker exposed to BME showed significantly reduced plasma cholesterol compared with females from a reference site. Mixed-function oxygenase (MFO) activity was significantly induced in β-sitosterol- and BME-exposed fish. Both BME and β-sitosterol were shown to affect biological responses through more than one mechanism of action. These studies suggest that β-sitosterol could contribute to some of the physiologic effects of pulp and paper mill effluents.
Persistence and distribution of 4-nonylphenol following repeated application to littoral enclosures
Authors: Heinis Larry J , Knuth Michael L , Liber Karsten , Sheedy Barbara R , Tunell Renee L , Ankley Gerald T
Published: March 2010

The persistence and distribution of 4-nonylphenol (NP) were monitored for 440 d, following application to 18 littoral enclosures (4 × 7–8 m), situated in a 2-ha mesotrophic pond near Duluth, Minnesota. Application was accomplished by subsurface, gravity-fed injection over a 20-d period, with a 2-d frequency, to achieve nominal aqueous concentrations of 0, 3, 30, 100, and 300 μg/L. Mean maximum concentrations in the water over the 20-d application period ranged from 75.7 to 81.0% of nominal for the three highest treatment levels and was 181% of nominal at the lowest treatment level. Water was the major compartment, on a mass balance basis, for NP until 2 to 4 d after the application period, with a mean time to 50% dissipation (DT50) of 0.74 d and a mean time to 95% dissipation (DT95) of 13.8 d. 4-Nonylphenol partitioned to enclosure wall material, macrophytes, and sediment within 2 d of initial application. Macrophytes accumulated maximum NP concentrations of 11.5 and 139 mg/kg 1 to 2 d after the application period at the 30- and 300-μg/L treatment levels, respectively. Mean DT50 and DT95 estimates of NP persistence in/on the macrophytes were 10.3 and 189 d, respectively. Sediment from the 30- and 300-μg/L treatments accumulated maximum dry weight NP concentrations of 2.74 and 27.4 mg/kg, respectively within 20 to 48 d of the first application. The mean sediment porewater NP concentration was 18.6 μg/L for the period 2 to 34 d after application 1 at the 300-μg/L treatment. The sediment was the primary sink for NP 440 d after the initial application with a concentration of 1.97 mg/kg at the 300-μg/L treatment. Mean sediment DT50 and DT95 values were 66.0 and 401 d, respectively, indicating a long-term persistence of NP. Ecocores collected 1 d after the final NP application did not show significant decreases in sediment NP concentration during a 55-d incubation period, corroborating the NP persistence observed in the littoral enclosures.
Preliminary survey of lead poisoning of Steller's sea eagle (Haliaeetus pelagicus) and white-tailed sea eagle (Haliaeetus albicilla) in Hokkaido, Japan
Authors: Kim Eun-Young , Goto Rie , Iwata Hisato , Masuda Yasushi , Tanabe Shinsuke , Fujita Shoichi
Published: March 2010

Concentrations of lead, mercury, and cadmium in the liver, kidney, and muscle of four Steller's sea eagles (Haliaeetus pelagicus) and one white-tailed sea eagle (Haliaeetus albicilla) that were found dead or debilitated and subsequently died in Hokkaido, Japan, from 1986 to 1997 were determined. High lead concentrations (>70 μg/g dry weight) were detected in the liver of two Steller's sea eagles and the white-tailed sea eagle. Lead shot was also found in the intestine and gizzard of one Steller's sea eagle and the white-tailed sea eagle, respectively. Mercury and cadmium concentrations in the tissues of these raptors were low, implying that the toxicities of these elements were negligible. These results indicate that eagles in Hokkaido are suffering from secondary poisoning through ingestion of lead shot embedded in the tissue of their prey.
Randomly amplified polymorphic DNA profile-based measures of genetic diversity in crayfish correlated with environmental impacts
Authors: Krane Dan E , Sternberg David C , Burton G Allen
Published: March 2010

Environmental insults diminish an ecosystem's ability to maintain productive and adaptable populations of organisms. We have analyzed randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR)-generated DNA profiles of naturally occurring rusty crayfish (Orconectes rusticus) populations from eight different populations collected from three separate sets of Ohio (USA) streams and find that changes in the underlying genetic diversity of these populations are significantly correlated (n = 144, p ≪ 0.001) with the extent to which they have been exposed to anthropogenic stressors. Because a population's genetic diversity is largely responsible for its vigor and ability to adapt to subsequent stressors, these results suggest that RAPD-PCR-based measures of genetic diversity may be suitable for development as a sensitive means of directly assessing the impact of stressors upon ecosystems.
Toxicity identification evaluation of metal-contaminated sediments using an artificial pore water containing dissolved organic carbons
Authors: Boucher Anne M , Watzin Mary C
Published: March 2010

Recent investigations of sediment-associated pollutants in Lake Champlain indicated significant contamination with As, Mn, and Ni in Outer Malletts Bay, Vermont, USA. Ceriodaphnia dubia exposed to sediment pore water from several sites in Outer Malletts Bay showed repeatable, acute mortality at only one site. A toxicity identification evaluation (TIE) was conducted on pore water to determine the contaminants causing mortality at this site. Unlike most TIE applications, the dilution water used in these tests was formulated to match the hardness, alkalinity, pH, conductivity, and dissolved organic carbon content of the pore water. Results from phase I of the TIE indicated that divalent metals may be responsible for toxicity. Phase II results revealed levels of Mn above LC50 values. Spiking experiments employed in phase III confirmed Mn as the principal toxicant in sediment pore water. The formulated pore water worked well and helped ensure that toxicant behavior was influenced primarily by each TIE manipulation and not by physical and chemical differences between the dilution and site water. Although the Mn toxicity at this site may be the result of its unique geomorphology, this situation underscores the need to look broadly for potential toxicants when evaluating contaminated sites.
Seasonal mercury levels in phytoplankton and their relationship with algal biomass in two dystrophic shield lakes
Authors: Kirkwood Andrea E , Chow-Fraser Patricia , Mierle Greg
Published: March 2010

Our study focused on the seasonal dynamics of total Hg in the phytoplankton (living and dead) of two dystrophic shield lakes (Mouse and Ranger). Phytoplankton samples were taken from metalimnetic and hypolimnetic depths in the euphotic zone and were collected and analyzed using ultraclean techniques. In both lakes, phytoplankton Hg (PHYTO-Hg) levels (pg/L) in the metalimnion did not significantly change among dates over the season, although Ranger Lake exhibited significant differences between Hg values measured at the beginning and end of the season. In contrast, PHYTO-Hg significantly increased in the hypolimnia of both lakes by the end of the season. Combined influences of external Hg inputs, remineralization, phytoplankton sedimentation, and increased methylmercury production in the hypolimnia over the season may have contributed to these trends. A highly significant positive relationship existed between PHYTO-Hg levels and whole-water Hg levels (r2 = 0.90), and the mean bioconcentration factor for Hg between the water column and phytoplankton was significantly higher in the hypolimnion compared to the metalimnion for both lakes. In most cases, parameters associated with algal biomass had significant positive correlations with PHYTO-Hg levels. Weight-specific PHYTO-Hg (pg/mg dry weight) varied significantly over the season, and there were interlake differences with respect to seasonal trends. On the basis of these results, we recommend that future sampling regimes include collection of phytoplankton at different limnetic depths throughout the season to account for spatial and temporal variations. Weight-specific Hg levels in phytoplankton could not be explained well by the parameters tested, and the only significant regressions were with parameters reflecting algal biomass. This study provides in situ evidence of Hg accumulation in lake phytoplankton as a function of algal biomass on a seasonal basis (as opposed to biodilution) and stresses the need to confirm these trends in other lake systems.
Evaluation of ability of reference toxicity tests to identify stress in aboratory populations of the amphipodHyalella azteca
Authors: MCnulty Ellen W , Dwyer F James , Ellersieck Mark R , Greer Eugene I , Ingersoll Christopher G , Rabeni Charles F
Published: March 2010

Standard methods for conducting toxicity tests imply that the condition of test organisms can be established using reference toxicity tests. However, only a limited number of studies have evaluated whether reference toxicity tests can actually be used to determine if organisms are in good condition. at the start of a test. We evaluated the ability of reference toxicants to identify stress associated with starvation in laboratory populations of the amphipod Hyalella azteca using acute toxicity tests and four reference toxicants: KCl, CdCl2, sodium pentachlorophenate (NaPCP), and carbaryl. Stress associated with severe starvation was observed with exposure of amphipods to carbaryl or NaPCP but not with exposure to KCl or CdCl2 (i.e., lower LC50 with severe starvation). Although the LC50s for NaPCP and carbaryl were statistically different between starved and fed amphipods, this difference may not be biologically significant given the variability expected in acute lethality tests. Stress associated with sieving, heat shock, or cold shock of amphipods before the start of a test was not evident with exposure to carbaryl or KCl as reference toxicants. The chemicals evaluated in this study provided minimal information about the condition of the organisms used to start a toxicity test. Laboratories should periodically perform reference toxicity tests to assess the sensitivity of life stages or strains of test organisms. However, use of other test acceptability criteria required in standard methods, such as minimum survival, growth, or reproduction of organisms in the control treatment at the end of a test, provides more useful information about the condition of organisms used to start a test compared to data generated from reference toxicity tests.
Ecological effects of mosquito control on zooplankton, insects, and birds
Authors: Niemi Gerald J. , Hershey Anne E , Shannon Lyle , Hanowski Joann M , Lima Ann , Axler Richard P , Regal Ronald R
Published: March 2010

We completed an integrated, 6–year study on the potential ecological effects of two mosquito control agents, methoprene (applied as AltosidTM sand granules) and Bacillus thuringiensis var. israelensis (Bti, applied as Vectobac-GTM granules), on zooplankton, insects, and breeding birds in wetlands of central Minnesota, USA, from 1988 to 1993. The study was a before-and-after design with pretreatment (1988-1990) and posttreatment (1991–1993) of 27 wetlands. Study sites were randomly selected and placed within one of three groups of sites, nine control, nine Bti-treated, and nine methoprene-treated. Selected populations of zooplankton, insects, and breeding birds were sampled within each of these wetlands. Insect densities were reduced by 57 to 83% and biomass was reduced by 50 to 83% in the second (1992) and third (1993) years of treatment. No negative effects on zooplankton or breeding birds could be attributed to treatment or changes to insect communities. Many factors may explain the lack of effects on breeding birds including, reductions in insects occurred after the nesting season was over, nest loss rates due to predation were very high (70%) and may have been a greater limiting factor to birds than mosquito control, and the density of breeding birds may be below carrying capacities, especially because not all wetlands in the landscape were treated and sufficient food may have been available. It is unclear what the long-term consequences of insect reductions mean to wetland health. The lack of close coupling between zooplankton, insects, and breeding birds probably reflects the ecological complexity of these wetlands such as the presence of other limiting factors on population distribution and abundance. Although the study period was relatively long (3 years of treatment) compared with most ecological studies of pesticides, it may not have been long enough to fully predict the effects of decades of continued mosquito control.