bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory analyses of the potential toxicity of sediment-associated polydimethylsiloxane to benthic macroinvertebrates
Authors: Henry Kevin S , Wieland Willemien H , Powell David E , Giesy John P 
Published: March 2010

Abstract
Polydimethylsiloxane (PDM)is widely used in a number of industrial processes and consumer products that result in down-the-drain disposal. The log p value for the PDMS used in the present study was 10, and the vapor pressure and water solubility values were below detection limits. These physicochemical characteristics and a measured degradation rate of 3% after six months in moist soils suggest that PDMS may accumulate in aquatic sediments. Sediment toxicity tests with the amphipod Hyalella azteca and with larvae of the midge Chironomus tentans were used to assess the potential for toxicity of PDMS-amended sediments to benthic invertebrates in short-term (10-d) and whole-life-cycle (28 d for H. azteca, 50–65 d for C. tentans) exposures. Endpoints for short-term tests included survival and growth, while life-cycle assays considered survival, growth, reproduction, and, for C. tentans only, emergence. Short-term and life-cycle exposures to concentrations of ≥1,000 mg PDMS/kg sediment (dry wt) indicated that PDMS will not reduce survival, growth, or reproduction in H. azteca or C. tentans.
Background zinc concentrations in soil affect the zinc sensitivity of soil microbial processes—a rationale for a metalloregion approach to risk assessments
Authors: McLaughlin Mike J , Smolders Erik 
Published: March 2010

Abstract
Soil microbial processes are particularly sensitive to Zn, but great difficulty exists in deriving soil standards based on laboratory toxicity tests. Zinc toxicity data for soil microbial processes were collated from the literature, and their variability with soil properties was assessed. Data were screened for quality and reliability, and analysis was based on the highest metal dose at which no adverse effect was found (HNOAED). The HNOAED values were expressed on a pore-water basis and were found to be positively related to background concentrations of Zn in soil, also expressed on a pore-water basis. This suggests that soil microorganisms acclimate to indigenous concentrations of Zn in soil pore water, and this acclimation affects the subsequent response to Zn added as a pollutant. Thus, regions having low background Zn concentrations in soil pore water will be much more sensitive to Zn pollution than others having high background concentrations. A method to account for effects of background Zn on assessments of Zn toxicity is suggested where metalloregions are defined having common sets of abiotic and biotic factors that affect the toxicity of Zn. This approach could markedly improve regional or continental risk assessments for metals in the environment.
Shrimp—a dynamic model of heavy-metal uptake in aquatic macrofauna
Authors: Simas Teresa Castro , Ribeiro Ana Paula , Ferreira João Gomes 
Published: March 2010

AbstractA dynamic model for prediction of bioaccumulation in aquatic macrofauna is described. The model, entitled SHRIMP (Simulation of Heavy-metal Rate of Intake for Macrofaunal sPecies), consists of five coupled submodels, which simulate individual growth, population dynamics, metal transport in the abiotic part of the system, metal bioaccumulation at the organism level, and upscaling of individual contamination to the population scale. The sublethal effects of metal toxicity on individual and population levels are shown to act through the reduction of individual growth rates. The model was tested for cadmium and mercury using epibenthic crustacea from an estuarine system. Individual and population patterns of bioaccumulation were analyzed by comparing the simulated results of five different scenarios of dissolved metal concentrations. Model results suggest that the subtle effect of growth reduction due to metal toxicity is sufficient to cause a decrease on population numbers simply by affecting the growth of the mature females and males.
A rapid screening method for acid-volatile sulfide in sediments
Authors: Simpson Stuart L 
Published: March 2010

AbstractA new, direct method for the determination of acid-volatile sulfide (AVS) in sediments is presented. The method utilizes the direct reaction of Clines reagent with small amounts of sediment followed by colorimetric determination of AVS and offers fast analysis times without the need for specialized glassware or equipment. A comparison between AVS measured by this method and that measured by a purge-and-trap AVS method shows a linear relationship (r = 0.986, p &lt; 0.001), although the method underestimates the AVS concentration measured by the purge-and-trap method. Sample throughput by the direct AVS method is more than 10 times that of purge-and-trap methods. The applicability of the direct AVS method to the rapid screening of AVS concentrations in sediments and for evaluating sediment quality with respect to metal contamination is demonstrated.
Biotransformation of n-hexadecane by cell suspension cultures of Cinchona robusta and Dioscorea composita
Authors: Vega-Jarquin Carolina , Dendooven Luc , Magaña-Plaza Ignacio , Thalasso Frederic , Ramos-Valdivia Ana 
Published: March 2010

Abstract
This manuscript evaluates the phytotoxicity and biotransformation of n-hexadecane as well as peroxidase activity and cytochrome P450 concentration in microsomes for cell suspension cultures of Cinchona robusta and Dioscorea composita. Phytotoxicity was evaluated based on viability and growth. Cell cultures were exposed to a 2 and 4% (v/v) dose of n-hexadecane. The biotransformation of n-hexadecane was determined based on labeled recovery in polar, nonpolar, and cell residue fractions after cell culture extraction during exponential cell growth phase and stationary phase. Differences were observed in accumulation of label during cell growth phase and stationary phase for the cells of the two plants. Differences also were observed between phases for label in polar and nonpolar fractions. Thin-layer chromatography determined labeled intermediates and some were identified. The activity of peroxidase and concentration of cytochrome P450 was lower in C. robusta than in controls and greater in D. composita than in controls. In vitro biotransformation was not successful.
Stable carbon and nitrogen isotope analysis of TNT: Two-dimensional source identification
Authors: Coffin Richard B , Miyares Paul H , Kelley Cheryl A , Cifuentes Luis A , Reynolds C. Michael 
Published: March 2010

Abstract
Data from a combination of laboratory and fieldwork is presented to initiate testing of stable carbon and nitrogen isotope ratios to trace sources of TNT in contaminated soil and groundwater. Evaluation of these extraction methods resulted in 99.9 and 99.8% recovery of TNT with Soxhlet and solid-phase extraction (SPE), respectively. As a result of the high extraction efficiency, isotope fractionation did not occur, thus providing an accurate stable isotope value on TNT from laboratory and field samples. Subsequent experiments evaluated the stability of isotope signatures through incubations lasting up to four weeks with a 70% decline in the TNT concentration. During these experiments, no significant variation in stable carbon and nitrogen isotope ratios was measured. Five different sources of TNT, compared for stable carbon and nitrogen isotope ratios, showed a range of 4.2 and 15‰, respectively. This large range in the isotope ratios suggests excellent potential to trace sources in a complex environment. Finally, a site was surveyed for concentrations and isotope values of TNT extracted from groundwaters. Values from this site were substantially different relative to the variation measured on standards and in laboratory incubation experiments. The data set indicates good potential to use stable isotopes to determine TNT sources and fate in the environment.
Photodegradation of hydroxychlorothalonil in aqueous solutions
Authors: Armbrust Kevin L 
Published: March 2010

Abstract
Hydroxychlorothalonil is the principal degradation product of the fungicide chlorothalonil in soil, and it is routinely detected in leachate from golf course greens at concentrations as high as 2 ppm. However, it is not detected in receiving waters of shallow ponds. Irradiation with simulated sunlight degraded hydroxychlorothalonil in distilled-deionized water, phosphate buffer, and pond water with half-lives of approximately 30 min. Slower degradation was observed in solutions of NaCl and NaCN, suggesting photonucleophilic substitution reactions may be responsible for the degradation. Hydroxylated products resulting from the displacement of chlorine and cyano groups were detected within the first hour of irradiation but were subsequently degraded to small aliphatic acids (succinic, oxalic, and malonic acid) within 96 h. Simulations of aquatic dissipation of the chemical using the U.S. Environmental Protection Agency standard pond scenario in the exposure analysis modeling system indicate that the 30-min half-life measured in the laboratory would equate to a half-life of 2.6 d in a 2-m-deep pond and as much as 3.4 d in seawater. Although hydroxychlorothalonil is moderately stable and mobile in soil, these data suggest that, in surface water, it should be rapidly degraded by sunlight to small aliphatic acids on transport into aquatic systems.
Fate of atrazine and alachlor in redox-treated ferruginous smectite
Authors: Xu Jennifer C , Stucki Joseph W , Wu Jun , Kostka Joel E , Sims Gerald K 
Published: March 2010

Abstract
The oxidation state of structural iron (Fe) in clay minerals exerts a large influence on clay surface chemistry and may affect the adsorption and degradation of pesticides in the environment. This effect, however, has been little investigated. In the present study, herbicides atrazine and alachlor were reacted with ferruginous smectite (sample SWa-1) in its oxidized, reduced (either chemically or bacterially), and reduced–reoxidized states. In some experiments the herbicide was labeled with 14C. Gas chromatography/mass spectrometry (GC-MS) was also used to detect alachlor degradation products. Compared to oxidized clays, reduction by both chemical and microbial treatments decreased the concentration of both herbicides in the surrounding solution. Reoxidized clay exhibited behavior similar to the oxidized clay. Hydrolysis–dechlorination of atrazine occurred in the presence of chemically reduced SWa-1, and GC-MS analysis of alachlor revealed at least 14 degradation products after treatment with reduced clay and only two with the oxidized clay. Interaction of atrazine and alachlor with the clay may be through a H bond with the waters of hydration surrounding interlayer cations, the extent of which should increase with increasing acidity; but under reduced conditions, the validity of this model is unclear. Reduction of structural Fe may affect pH-dependent phenomena in two ways: The increased surface charge density increases the number of hydrated interlayer cations, thereby enhancing surface acidity, and increased electron density at basal surface oxygens increases their Brønsted basicity. Atrazine could, therefore, adsorb and/or degrade through either acid or alkaline hydrolysis pathways. Increased reduction potential of the reduced clay surfaces may also promote degradation.
Butyltin compounds in sediments from the commercial harbor of Alexandria City, Egypt
Authors: Barakat Assem O , Kim Moonkoo , Qian Yaorong , Wade Terry L 
Published: March 2010

AbstractTributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) compounds were quantitatively determined in surface-sediment samples collected from 23 sites in the commercial harbor of Alexandria City, Egypt. Butyltin concentrations in sediments varied widely depending on the sample location, ranging from less than 0.1 to 186 ng g−1 of Sn for MBT, less than 0.1 to 379 ng g−1 of Sn for DBT, and 1 to 2,067 ng g−1 of Sn for TBT. Elevated TBT concentrations, ranging from 727 to 2,067 ng g−1 of Sn were observed in harbors, marinas, and near ship-repair facilities, indicating that the butyltin-containing, antifouling paints of boats and vessels are the major source of butyltin contamination. The TBT concentration decreased rapidly away from potential source areas of boat docking and repair facilities. The high relative concentrations of TBT in the sediments indicated that degradation processes in the sediments are minor, probably due to the anoxic sedimentary conditions at the sampling sites and/or relatively fresh input of TBT to these sites.
Characterization of dioxin-like activity of sediments from a Czech River Basin
Authors: Hilscherova Klara , Kannan Kurunthachalam , Kang Youn-Seok , Holoubek Ivan , Machala Miroslav , Masunaga Shigeki , Nakanishi Junko , Giesy John P 
Published: March 2010

Abstract
Synthetic organic chemicals are present in environmental compartments as complex mixtures and therefore their potential effects are difficult to predict. In this study, in vitro bioassays using wild-type fish and rat hepatoma cell lines and their corresponding recombinant cell systems were used to evaluate 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activity in extracts of sediments collected from rivers of the Czech Republic. All the sediment extracts elicited statistically significant responses in all the cell lines tested. For most sediment extracts, a complete dose–response relationship was obtained. The maximal efficacy of the samples was between 57 and 143% of the maximal induction elicited by TCDD. Greater responsiveness, sensitivity, and reproducibility were observed for recombinant than wild-type cells. Cell line-specific differences in the sensitivity to compounds present in the complex sediment extracts were observed. The TCDD equivalents (TCDD-EQs) determined from the different cell bioassays were correlated. Greater concentrations of TCDD-EQs were obtained with fish cell lines. The TCDD-EQs calculated from the results of chemical analysis of toxic equivalents (TEQs) were in good agreement with those determined by bioassays; the arly hydrocaron receptor (AhR)-effects of the identified chemicals appear to be generally additive. This indicates that most of the TCDD-like activity was accounted for by the compounds identified and quantified by instrumental analysis. Fractionation along with mass-balance calculations allowed identification of the active fractions and classes of compounds. Polycyclic aromatic hydrocarbons (PAHs) were found to be responsible for most of the AhR-mediated activity in sediments.
Response of phytoplankton communities to liquid creosote in freshwater microcosms
Authors: Sibley Paul K , Harris Megan L , Bestari Ketut T. (Jim) , Steele Tracey A , Robinson Richard D , Gensemer Robert W , Day Kristen E , Solomon Keith R 
Published: March 2010

AbstractWe assessed the response of phytoplankton communities in aquatic microcosms to single applications of liquid creosote. The creosote was applied to 14 microcosms at concentrations ranging from 0.06 to 109 mg/L. Two microcosms served as controls. Phytoplankton samples were collected from each microcosm one week and 1 d before treatment and at 7 and 21 d after treatment. Temporal changes (response–recovery) in phytoplankton community composition were assessed with principal response curves. Creosote had no direct toxic effect on the phytoplankton community based on total abundance and number of taxa. Population levels declined in all treatments between day −1 and day 7, but this trend mirrored a similar decline in the control microcosms. At both 7 and 21 d after treatment, population densities and number of taxa in most treatments exceeded those in the controls and exhibited a parabolic relationship relative to creosote concentration. This relationship was most pronounced at 21 d, at which time population densities and number of taxa at intermediate concentrations were up to twice those at low and high concentrations. This response pattern seems to represent an indirect response to impacts on zooplankton and a corresponding reduction in grazing pressure. In contrast, total algal biomass declined 52 to 97% relative to the controls at all but the lowest creosote concentration at 7 d. This apparent decline was due to a significant proliferation of the alga Closterium moniliforme in the controls and low creosote concentration. At 21 d, no difference was found in total biomass between treated and control microcosms. The results of this study suggest that creosote does not pose a significant direct risk to phytoplankton at concentrations likely to be encountered in most contaminated aquatic environments; however, stimulation of algal populations could occur in situations of long-term chronic exposure or spill events that remove predatory zooplankton populations.
Trace element accumulation in hawksbill turtles (Eretmochelys imbricata) and green turtles (Chelonia mydas) from Yaeyama Islands, Japan
Authors: Anan Yasumi , Kunito Takashi , Watanabe Izumi , Sakai Haruya , Tanabe Shinsuke 
Published: March 2010

Abstract
Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Ba, Hg, Tl, and Pb) were determined in the liver, kidney, and muscle of green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Yaeyama Islands, Okinawa, Japan. Accumulation features of trace elements in the three tissues were similar between green and hawksbill turtles. No gender differences in trace element accumulation in liver and kidney were found for most of the elements. Significant growth-dependent variations were found in concentrations of some elements in tissues of green and hawksbill turtles. Significant negative correlations (p &lt; 0.05) were found between standard carapace length (SCL) and the concentrations of Cu, Zn, and Se in the kidney and V in muscle of green turtles and Mn in the liver, Rb and Ag in kidney, and Hg in muscle of hawksbill turtles. Concentrations of Sr, Mo, Ag, Sb, and Tl in the liver, Sb in kidney, and Sb and Ba in muscle of green turtles and Se and Hg in the liver and Co, Se, and Hg in kidney of hawksbill turtles increased with an increase in SCL (p &lt; 0.05). Green and hawksbill turtles accumulated extremely high concentrations of Cu in the liver and Cd in kidney, whereas the levels of Hg in liver were low in comparison with those of other higher–trophic-level marine animals. High accumulation of Ag in the liver of green turtles was also observed. To evaluate the trophic transfer of trace elements, concentrations of trace elements were determined in stomach contents of green and hawksbill turtles. A remarkably high trophic transfer coefficient was found for Ag and Cd in green turtles and for Cd and Hg in hawksbill turtles.
Heavy metals and selenium in feathers of great tits (Parus major) along a pollution gradient
Authors: Janssens Ellen , Dauwe Tom , Bervoets Lieven , Eens Marcel 
Published: March 2010

AbstractWe evaluated the use of great tit (Parus major) feathers as biomonitors for heavy-metal pollution and tested whether there were differences in metal levels in feathers as a function of location, age (first year or older), or gender. In 1998 and 1999, we collected the outermost tail feathers of 185 great tits from four sites along a presumed pollution gradient and one reference site in Antwerp (Belgium) and analyzed them for calcium, selenium, and 13 heavy metals (silver, aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, mercury, manganese, nickel, lead, and zinc). Silver, arsenic, cadmium, cobalt, copper, mercury, nickel, lead, selenium, and zinc concentrations were significantly higher closest to the pollution source (UM site) compared with the other four sites. Heavy-metal and selenium levels were on average 2 to 40 times higher at the UM site compared with the reference site. Aluminum, calcium, and iron levels were not significantly different among sites. We found no general age- or gender-related differences in metal levels except for arsenic and iron, where a significant interaction between site and gender was observed. Our results suggest that feathers of great tits might be useful biomonitoring tools because they reflect the environmental contamination by heavy metals well.
Development of copepod nauplii to copepodites—a parameter for chronic toxicity including endocrine disruption
Authors: Andersen Henrik Rasmus , Wollenberger Leah , Halling-Sørensen Bent , Kusk Kresten Ole 
Published: March 2010

Abstract
Test compounds including natural hormones, endocrine disrupters, environmentally occurringcompounds, and reference compounds were tested for acute toxicity and inhibitory effect on larval development in the copepod Acartia tonsa. Three compounds, 17α-ethinylestradiol, p-octylphenol, and tamoxifen, known for their differing effects on the vertebrate estrogen system, were potent inhibitors of naupliar development. Other estrogens, 17β-estradiol, estrone, and bisphenol A, had little potency. Testosterone and progesterone did not inhibit development, but the antiandrogen flutamide had inhibitory effect. Juvenile hormone III was a potent inhibitor, as was expected based on the literature, whereas 20-hydroxyecdysone had no effect. 3,4-Dichloroaniline was inhibitory on development, whereas other control compounds, potassium dichromate and 3,5-dichlorophenol, did not inhibit development. Six of the 17 test compounds had 50% lethal concentration to 50% effective concentration (EC50) ratios higher than 10. The results suggest that naupliar development, as a parameter, is able to detect hormonal disrupters in addition to other chemicals that have other specific modes of action.
Subchronic exposure of BALB/c and C57BL/6 strains of Mus musculus to the radioactive environment of the Chornobyl, Ukraine exclusion zone
Authors: Rodgers Brenda E , Chesser Ronald K , Wickliffe Jeffrey K , Phillips Carleton J , Baker Robert J 
Published: March 2010

Abstract
Environmental contamination resulting from the Chornobyl, Ukraine, disaster offers a unique opportunity to examine the in vivo biological effects of chronic, low-dose exposure to radiation. Laboratory studies of acute exposure to ionizing radiation have been used to estimate risk and potential human health effects by the extrapolation of laboratory data to situations of low-dose environmental radiation exposure. Few studies, however, have explored the biological consequences of low-dose exposure via in situ environmental radiation in a sentinel species. In the present study, laboratory strains of Mus musculus (BALB/c and 57BL/ 6) were placed in environmental enclosures in the Red Forest region of the Chornobyl exclusion zone. Blood samples were obtained every 10 d, and the micronucleus (MN) test was employed to assess the potential for cytogenetic damage from exposure to Chornobyl radiation. Radionuclide uptake was monitored throughout the study, and dose was estimated for each individual as well as for their offspring. Total dose for the mice experimentally exposed to this environment averaged 1162 mGy for BALB/c (30 d) and 1629 mGy for C57BL/6 (40 d). A higher MN frequency for both strains was observed at day 10, although this change was only statistically significant in the C57BL/6 mice (χ23 = 13.41, p = 0.003). Subsequent samples from C57BL/6 resulted in values at or less than the initial frequencies. In BALB/c mice, an increase in MN was also evident at day 30 (χ22 = 10.38, p = 0.006). The experimental design employed here allows for the incorporation of traditional laboratory strains, as well as transgenic strains of Mus, as sentinels of environmental radiation contamination.