bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of metal mixture (Cu, Zn, Pb, and Ni) on cadmium partitioning in littoral sediments and its accumulation by the freshwater macrophyte Eriocaùlon septangulàre
Authors: Stewart A Robin , Malley Diane F 
Published: March 2010

Abstract
The effect of a metal mixture (Cu, Zn, Pb, and Ni) on Cd fractionation in sediment and its accumulation by the freshwater macrophyte Eriocaùlon septangulàre was examined in an in situ experiment in the littoral zone at the Experimental Lakes Area, northwestern Ontario, Canada. Fresh sediment was spiked with Cd alone and together with the metal mixture at three concentration levels. Macrophytes were planted in the spiked sediment and placed at a water depth of 0.5 m. The distribution of Cd among sediment fractions (easily reducible [ER], reducible [R-ER], and organic [ORG]), pore water, and macrophytes was determined every 2 weeks for 10 weeks. Small differences among treatment levels in the recovery of Cd from the geochemical fractions were observed after 2 and 8 weeks but not after 10 weeks. At the highest concentration of the metal mixture, Cd repartitioned from the ER fraction onto the R-ER fraction after 2 weeks in situ. After 10 weeks, Cd was accumulated by the shoots (&lt;2.6 μg/g dry weight) and roots (&lt;45 μg/g dry weight) of E. septangulàre and had not reached steady state. Significantly higher Cd concentrations were found in the shoots of plants in the treatment with Cd alone and the treatment with the highest concentration of the metal mixture than in treatments with intermediate levels of the mixture. Partitioning of Cd among geochemical fractions in sediment alone did not explain differences in tissue Cd concentrations related to treatment level.
Heavy metals in Franklin's gull tissues: Age and tissue differences
Authors: Burger Joanna , Gochfeld Michael 
Published: March 2010

Abstract
We examined the concentrations of lead, cadmium, chromium, mercury, manganese, and selenium in feathers, liver, kidney, heart, brain, and breast muscle of Franklin's gulls (Larus pipixcan) nesting in northwestern Minnesota, USA, in 1994. Between 16% (chromium) and 71% (selenium, manganese) of the variation in metal concentrations was explained by tissue and age, except for selenium and arsenic, which were only explained by tissue. Of 35 possible differences (seven metals in five tissues), 24 significant age-related differences were found in Franklin's gulls, with young generally having lower concentrations of metals in all of their tissues than adults. A notable exception was the liver; young had significantly higher concentrations of selenium, chromium, manganese, and arsenic than did adults. Three notable findings were the following: young had significantly higher concentrations of selenium, chromium, manganese, and arsenic in their liver than did adults; young had 30 times as much chromium in the liver than adults; and adults had greatly elevated concentrations of cadmium in feathers, kidney, and liver.
Comparison of dissolved and total metals concentrations from acute tests with saltwater organisms
Authors: Lussier Suzanne M , Boothman Warren S , Poucher Sherry , Champlin Denise , Helmstetten Andrea 
Published: March 2010

Abstract
Aquatic life criteria (ALC) have traditionally been expressed for metals in terms of total-recoverable or acid-soluble concentrations. Recent U.S. Environmental Protection Agency policy recommended use of dissolved metal concentrations for setting water quality standards. Criteria derived from previous tests could be expressed in terms of dissolved metals if ratios of dissolvedto-total concentrations in those tests were consistent. Using those metals with insufficient dissolved metals data to directly derive criteria (arsenic (III), cadmium, chromium (VI), lead, nickel, selenium (IV), and zinc), we measured both total and dissolved metal concentrations in acute saltwater static and flow-through tests. Exposure conditions simulated those of original tests used to derive ALC. Partitioning of metals between dissolved and particulate forms was very consistent. Dissolved metal concentrations were greater than 90% of total concentrations in all tests, exceeding 95% in 10 of 13 tests. Dissolved-to-total metal ratios did not vary significantly with concentration, time, or type of test. Biological responses were consistent with historical data. Results implied that in acute saltwater toxicity tests used to establish ALC, metals were primarily dissolved. Thus criteria developed for metals based on total concentrations should be equally valid when expressed in terms of dissolved concentrations.
Differences in survival functions of mosquitofish (Gambusia affinis) and sand shiner (Notropis ludibundus) genotypes exposed to pesticides
Authors: Sullivan Karen Brown , Lydy Michael J 
Published: March 2010

AbstractDifferential genotypic tolerance of two species of fish native to the Great Plains of North America (the western mosquitofish [Gambusia affinis] and the sand shiner [Notropis ludibundus]) was examined in 96-h acute exposures to the pesticides lindane and parathion. Although a significant amount of data is available indicating that heavy metals cause selective genotypic mortality in aquatic organisms, very few studies have focused on the effects of pesticides on population genetic structure. Fish used in this experiment were captured from field populations in Kansas, USA, and acclimated to laboratory conditions for 1 month before the acute toxicity tests. Two hundred individuals of each species were exposed, in two separate experiments, to estimated LC70 concentrations of each pesticide for 96 h. Dead individuals were removed at 3-h intervals allowing for comparison of genotypic times-to-death. Individuals of each species were electrophoretically examined at two polymorphic loci. Phenotypes of mosquitofish were determined for phosphoglucose mutase (PGM) and malic enzyme (ME). Phenotypes of sand shiners were determined for PGM and aspartate aminotransferase (AAT). Three of eight statistical tests (two species × two loci × two pesticides) indicated significant differences among survival curves of genotypic classes. Genotypes of ME and PGM of mosquitofish exhibited significantly different survivorship functions in the parathion and lindane time-to-death tests, respectively. Genotypes of AAT of sand shiners exhibited significantly different survivorship curves when exposed to lindane. Given certain experimental limitations, these results support a continued examination of population genetic characteristics as biomarkers of environmental contamination.
Nuclear DNA content variation and double-strand DNA breakage in white-footed MICE (Peromyscus leucopus) collected from abandoned strip mines, Oklahoma, USA
Authors: Husby Michael P , McBee Karen 
Published: March 2010

Abstract
White-footed mice (Peromyscus leucopus) were collected during the spring, summer, and fall from four metal-polluted abandoned mines and three reference sites in eastern Oklahoma. Two mines in east-central (Okmulgee County) Oklahoma, USA, were matched with a nearby reference site, as were two mines in northeastern Oklahoma (Craig County). A third, remote reference site was located outside the Oklahoma coal belt in north-central Oklahoma (Payne County). Intercellular DNA content variation, measured as a coefficient of variation (CV) of nuclear DNA content among 20,000 cells per animal, was determined for splenocytes of individuals by flow cytometry. Double-strand breakage in liver DNA from the same animals was compared using agarose gel electrophoresis. Mice trapped from mines were expected to have more intercellular DNA content variation and more DNA breakage when compared with mice from the matched and remote reference sites. With one exception, mice from mine sites did not show any significant increase in nuclear DNA content variation during any season. Electrophoresis revealed that mice from both Okmulgee County mines had significantly more DNA breakage compared with the intracounty reference site in the spring. In the summer, mice from one Craig County mine had significantly higher levels of DNA breakage compared with the remote reference.
Model of biota-sediment accumulation factor for polycyclic aromatic hydrocarbons
Authors: Thomann Robert V , Komlos John 
Published: March 2010

AbstractA model of the BSAF is constructed for PAHs using a steady-state representation of a benthic food web of a small creek. Analyses of the data collected by others on sediment, crayfish and sunfish PAH indicate that for the crayfish, the BSAF (kg org C kg lipid−1) range over log Kow is relatively narrow between 0.01 and 0.1. For the sunfish, a marked decline occurs in the station average BSAF with increasing log Kow to values ranging from 0.00001 to 0.005. A separation also occurs in the behavior of the PAH groups, with the unsubstituted PAHs constituting an approximate lower bound on the entire set of PAHs. Model calibration to crayfish and sunfish BSAF is accomplished through assignment of PAH (Kow) functions derived from laboratory data. The substituted naphthalenes in contrast to the unsubstituted PAHs are calculated to behave similarly to PCBs but lower by about one order of magnitude. Analyses of the model calibration indicate that (1) relative to the sunfish, the crayfish appear to exhibit reduced metabolism and higher gut assimilation efficiencies resulting in BSAFs different from sunfish BSAFs; (2) for the sunfish, the BSAF for unsubstituted PAHs declines rapidly with increasing Kow primarily because of low gut assimilation efficiency and increased metabolism and not because of reduced bioavailability of sediment PAH; and (3) the relative contribution of the food route and water route to the BSAF varies with Kow.
Quantitative structure-property relationships for the chemical reactivity of acrylates and methacrylates
Authors: Freidig Andreas P , Verhaar Henk J M , Hermens Joop L M 
Published: March 2010

Abstract
Reactivity towards three different nucleophiles was measured for a training set of six acrylates and seven methacrylates. The reactions studied were neutral and base-catalyzed hydrolysis and Michael addition of reduced glutathione (GSH). A linear free energy relationship (LFER) was established for the base-catalyzed hydrolysis rate constants of methacrylates, with the Taft parameter σ* as single descriptor. The GSH reactivity could be modeled with a partial least square regression (PLS) using four quantum chemical ground state parameters describing the difference in frontier orbital interaction and coulombic forces within the training set. Literature data for GSH reactivity was used to test the applicability of the PLS model. Differences in acute fish toxicity for structurally similar acrylates and methacrylates could be explained by their different potency as Michael-type acceptors.
Correlation between response of human cell line and distribution of sediment polycyclic aromatic hydrocarbons and polychlorinated biphenyls on Palos Verdes Shelf, California, USA
Authors: Anderson Jack W , Zeng Eddy Y , Jones Jennifer M 
Published: March 2010

Abstract
Sections of a sediment core collected from Station 7C near the County Sanitation Districts of Los Angeles County, California, USA, outfall were analyzed for total organic carbon (TOC), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). In addition, the biological responses to extracts from the same samples were determined using the P450 reporter gene system (RGS) assay. The profiles of TOC, PAHs, and PCBs were consistent in illustrating the predischarge baseline and the effects of improving wastewater treatment. Induction of the CYP1A1 gene using P450 RGS was correlated with total PAHs (r2 = 0.47) and better correlated with the B[a]P toxic equivalency quotients (r2 = 0.63) calculated using toxic equivalency factors (TEFs) derived from P450 RGS analyses of individual high molecular weight (4 to 6 rings) PAHs. Results from short (6 h) and long (16 h) exposures using the RGS assay suggested that a portion of the induction was from the slower acting chlorinated hydrocarbons (coplanar PCBs, dioxins, furans, etc.). Coplanar PCBs in the amounts of 0.9 to 3.1 μg/g were found in three core sections analyzed; hence, the induction of RGS was likely produced by both PAHs and coplanar PCBs. Since dioxins and furans were not analyzed, their contributions to the RGS responses are unknown. The RGS assay may be used to screen samples for potential toxicological importance before conducting costly chemical analyses.
Use of flow cytometry to detect genetic damage in mallards dosed with mutagens
Authors: Whittier Joanna B , McBee Karen 
Published: March 2010

Abstract
Data derived from mammalian, plant, and microbial models of genotoxicity may not be applicable to birds because of differences in avian genetic structure and physiology. The objective of this study was to develop a standardized, nonlethal genotoxicity assay for use with birds based on modification of a mammalian assay, flow cytometric measurement of variation in nuclear DNA content. Blood samples were collected from brachial veins of juvenile mallards (Anas platyrhynchos) before and after they were administered an oral dose of either methyl parathion (7.5, 15.0, or 30.0 mg/kg body weight), triethylenemelamine (0.25, 0.50, or 1.0 mg/kg body weight), or a solvent control. Cells were examined for nine parameters of DNA content and cell cycle kinetics. Results from blood samples were compared with results from spleen tissue, which is more commonly used in flow cytometric assays. Results were divided into three analysis groups: predose, postdose, and difference between pre- and postdose endpoints. Within triethylenemelamine dose groups, significant variation was found only in the predose postsynthetic gap (phase of cells after DNA synthesis; G2) to presynthetic gap (phase of cells before DNA synthesis; G1) ratio. Methyl parathion groups varied significantly in two parameters: postdose coefficient of variation of the G2 peak and postdose G2 to G1 ratio. Dose levels of positive control groups may have been too low to elicit a definite genotoxic response. Despite the limited response in the positive control, evidence of disturbance of normal cell cycle kinetics suggests flow cytometry is a viable alternative for genotoxicity analyses in birds.
Exploring the effects of consumer–resource dynamics on contaminant bioaccumulation by aquatic herbivores
Authors: Spencer Matthew , Fisher Nicholas S , Wang Wen-Xiong 
Published: March 2010

Abstract
We explore the consequences of consumer–resource interactions for bioaccumulation in two aquatic systems (cadmium accumulation in Dreissena polymorpha and polychlorinated biphenyl accumulation in calanoid copepods). We explicitly link the feeding and growth rates of consumers to the abundance of resources under a variety of assumptions about the nature of the interactions between them. The models are parameterized using field and laboratory data, and predictions are quantitatively compared with field-measured distributions of tissue concentrations. Different assumptions about consumer–resource interactions result in different predicted distributions of tissue concentrations and illustrate the way these interactions constrain the bioaccumulation of contaminants. Linking feeding and growth rates to resource abundances will be important whenever these abundances change over time. User-friendly software will make these ideas accessible to nontheoreticians.
Thermodynamic investigation of trichloroethylene adsorption in water-saturated microporous adsorbents
Authors: Farrell James , Hauck Benjamin , Jones Martin 
Published: March 2010

Abstract
Adsorption of trichloroethylene (TCE) in adsorbents containing hydrophilic and hydrophobic micropores was investigated in order to determine the mechanisms responsible for TCE adsorption on mineral solids. A high-pressure liquid chromatography method was used to measure TCE adsorption isotherms on three microporous adsorbents. Silica gel and zeolite type NaX were used as hydrophilic model adsorbents, and hexamethyldisilazane (HMDS)-treated silica gel was used as a model hydrophobic adsorbent. Batch uptake and desorption isotherms were also measured on the hydrophilic silica gel. Uptake of TCE by all three adsorbents was linear over the concentration range investigated. However, the silica gel desorption isotherm was highly nonlinear, as indicated by its Freundlich isotherm exponent of 0.58. Capillary phase separation into hydrophobic micropores was postulated as being responsible for the isotherm hysteresis. Supporting this hypothesis was the conformance of the TCE adsorption isotherm to Dubinin–Radushkevitch volume filling of micropores theory. The enthalpies for TCE adsorption on all three solids were determined by van't Hoff analysis of distribution coefficients measured over a temperature range from 5 to 90°C. The TCE adsorption enthalpies on the silica gel and HMDS silica gel were exothermic, but on the zeolite adsorption was endothermic. High exothermic adsorption enthalpies on the silica gel adsorbents indicated that TCE adsorption was occurring in hydrophobic micropores, and that adsorption on surfaces with large radii of curvature contributed only minimally to the total uptake. This indicates that the predominant mechanism for TCE adsorption on these mineral solids is not partitioning into the vicinal water layer.
Bioavailability and desorption characteristics of aged, nonextractable atrazine in soil
Authors: Johnson Stephanie E , Herman Janet S , Mills Aaron L , Hornberger George M 
Published: March 2010

Abstract
The bioavailability and desorption characteristics of nonextractable soil-aged atrazine were investigated to examine the significance of this potentially large contaminant fraction in agricultural soils. Radiolabeled atrazine-applied soil was aged for 3 months and then extracted by one of three methods—methanol-water (4: 1) at 75°C, acetone, and artificial soil water—representing a range of extraction efficiencies. Viable microcosms were constructed with the dried, extracted soil to compare rates and extents of microbially facilitated release and mineralization with desorption rates in sterile microcosms. The most rigorously extracted soil exhibited slow desorption over a 90-d period, but the other soil treatments showed continued slow sorption after reaching an initial maximum desorption concentration within 1 to 5 d. No microbially facilitated release of the nonextractable atrazine was detected for any of the treatments. Rates of ring-and chain-labeled atrazine mineralization declined with decreasing extractability of the soilassociated atrazine fraction. However, the extent of biodegradation (less than 2% of the total atrazine for all extracted soil treatments) was less than the extent of abiotic desorption. Mass-balance calculations suggest that all biodegradation occurred in the dissolved phase.
Biomonitoring of mercury pollution in a wetland near Ravenna, Italy by translocated bivalves (Mytilus galloprovincialis)
Authors: Cattani Otello , Fabbri Daniele , Salvati Marco , Trombini Claudio , Vassura Ivano 
Published: March 2010

Abstract
An active biomonitoring experiment using mussels (Mytilus galloprovincialis) was performed in Pialassa Baiona, a mercury-polluted coastal wetland near Ravenna, Italy. Three stations (A, B, and C) were selected along the south to north axis. Following a 52-d field exposure, organisms transplanted in the southernmost polluted area (station A) showed mean mercury concentration values of 660 ng/g (dry weight), 4.4 times the initial background level, and were still accumulating mercury. Mussels in both the central area (station B) and the northern area (station C) seemed to reach a steady state with mean mercury concentration values of 323 and 412 ng/g, respectively. This field experiment is the first study carried out in the Ravenna wetlands to evaluate mercury bioavailability in this environment. Finally, the efficiency of the population of Mytilus galloprovincialis selected for the field experiment as mercury bioaccumulators was tested in a laboratory experiment that revealed that up to 135 μg/g (dry weight) could be reached after 77 d of exposure to mercury-polluted water.
Concentration effects of 1,2-dichlorobenzene on soil microbiology
Authors: Thompson Ian P , Bailey Mark J , Boyd Elaine M , Maguire Nicola , Meharg Andrew A , Ellis Richard J 
Published: March 2010

Abstract
The effect of increasing concentrations (65, 130, 325, 1,300, and 3,250 μg/g soil dry weight) of 1,2-dichlorobenzene (1,2-DCB) on the microbial biomass, metabolic potential, and diversity of culturable bacteria was investigated using soil microcosms. All doses caused a significant (p &lt; 0.05) decrease in viable hyphal fungal length. Bacteria were more tolerant, only direct total counts in soils exposed to 3,250 μg/g were significantly (p &lt; 0.05) lower than untreated controls, and estimates of culturable bacteria showed no response. Pseudomonads counts were stimulated by 1,2-DCB concentrations of up to 325 μg/g; above this level counts were similar to controls. Fatty acid methyl ester analysis of taxonomic bacterial composition reflected the differential response of specific genera to increasing 1,2-DCB concentrations, especially the tolerance of Bacillus to the highest concentrations. The shifts in community composition were reflected in estimates of metabolic potential assessed by carbon assimilation (Biolog) ability. Significantly fewer (p &lt; 0.05) carbon sources were utilized by communities exposed to 1,2-DCB concentrations greater than 130 μg/g (&lt;64 carbon sources utilized) than control soils (83); the ability to assimilate individual carbohydrates sources was especially compromised. The results of this study demonstrate that community diversity and metabolic potential can be used as effective bioindicators of pollution stress and concentration effects.
Exposure of great egret (Ardea albus) nestlings to mercury through diet in the everglades ecosystem
Authors: Frederick Peter C , Spalding Marilyn G , Sepälveda Maria S , Williams Gary E , Nico Leo , Robins Robert 
Published: March 2010

Abstract
We estimated exposure of great egret (Ardea albus) nestlings to mercury in food in the Florida Everglades, USA, by collecting regurgitated food samples during the 1993 to 1996 breeding seasons and during 1995 measured concentrations of mercury in individual prey items from those samples. Great egret nestlings had a diet composed predominantly of fish (&gt;95% of biomass), though the species composition of fish in the diet fluctuated considerably among years. Great egrets concentrated on the larger fish available in the marsh, especially members of the Centrarchidae. The importance of all nonnative fish fluctuated from 0 to 32% of the diet by biomass and was dominated by pike killifish (Belonesox belizanus) and cichlids (Cichlidae). Total mercury concentrations in prey fish ranged from 0.04 to 1.40 mg/kg wet weight, and we found a significant relationship between mass of individual fish and mercury concentration. We estimated the concentration of total mercury in the diet as a whole by weighting the mercury concentration in a given fish species by the proportion of that species in the diet. We estimate that total mercury concentrations in the diets ranged among years from 0.37 to 0.47 mg/kg fish (4-year mean = 0.41 mg/kg). We estimated total mercury exposure in great egret nestlings by combining these mercury concentrations with measurements of food intake rate, as measured over the course of the nestling period in both lab and field situations. We estimate that, at the 0.41 mg/kg level, nestlings would ingest 4.32 mg total mercury during an 80-day nestling period. Captive feeding studies reported elsewhere suggest that this level of exposure in the wild could be associated with reduced fledging mass, increased lethargy, decreased appetite, and, possibly, poor health and juvenile survival.