bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of grasses on herbicide fate in the soil column: Infiltration of runoff, movement, and degradation
Authors: Belden Jason B. , Coats Joel R. 
Published: November 2004

Abstract
The objective of the present study was to evaluate if the presence of grass or the type of grass influences the environmental fate of herbicides within a soil column. Intact soil columns were planted with either smooth brome, big bluestem, tall fescue, switchgrass, or a mixture of prairie grasses or were left unvegetated. Artificial runoff containing atrazine, metolachlor, and pendimethalin was applied to the columns and allowed to infiltrate, and the resulting leachate was collected at the bottom of the soil column. This process was repeated on day 7 with herbicide-fortified runoff and on days 14 and 21 with water only. Following the leaching experiments, soil from the columns was fortified with either [14C]atrazine or [14C]metolachlor to measure pesticide degradation potential. The mean time necessary for infiltration of the artificial runoff decreased from 7.5 h for unvegetated to 3.4 h for grassed soil columns, and the type of grass did not have a significant effect. Neither the type of grass nor the presence of grass caused a significant change in the total amount of herbicide that leached through the columns. However, the presence of some grasses did decrease the amount of herbicide that leached in the final two events (i.e., additions not fortified with herbicide). Fescue was the least effective, reducing the amount of leached atrazine and metolachlor by 13% and 33% respectively, and mixed prairie grass was most effective, with reductions of 43% and 44%, respectively. In addition, atrazine and metolachlor degraded more rapidly in soil vegetated by some grasses. Mixed prairie grass had the greatest effect, increasing atrazine mineralization by 260% and formation of metolachlor-bound residue by 760%.
Integrated fate modeling for exposure assessment of produced water on the Sable Island Bank (Scotian Shelf, Canada)
Authors: Berry Jody A. , Wells Peter G. 
Published: November 2004

Abstract
Produced water is the largest waste discharge from the production phase of oil and gas wells. Produced water is a mixture of reservoir formation water and production chemicals from the separation process. This creates a chemical mixture that has several components of toxic concern, ranging from heavy metals to soluble hydrocarbons. Analysis of potential environmental effects from produced water in the Sable Island Bank region (NS, Canada) was conducted using an integrated modeling approach according to the ecological risk assessment framework. A hydrodynamic dispersion model was used to describe the wastewater plume. A second fugacity-based model was used to describe the likely plume partitioning in the local environmental media of water, suspended sediment, biota, and sediment. Results from the integrated modeling showed that the soluble benzene and naphthalene components reach chronic no-effect concentration levels at a distance of 1.0 m from the discharge point. The partition modeling indicated that low persistence was expected because of advection forces caused by tidal currents for the Sable Island Bank system. The exposure assessment for the two soluble hydrocarbon components suggests that the risks of adverse environmental effects from produced water on Sable Island Bank are low.
Determination of optimized protocols for the extraction of anticholinesterasic compounds in environmental samples containing cyanobacteria species
Authors: Barros LÉLIA PACHECO CORRĚIA , Monserrat José Maria , Yunes JoãO Sarkis 
Published: November 2004

Abstract
The effects of temperature and pH during extraction of toxin(s) from the cyanobacterial genus Anabaena were studied. Different extracts were compared for their anticholinesterase potency against purified eel acetylcholinesterase. A lyophilized powder from Anabaeba spiroides cells was dissolved in ethanol, sonicated, and filtered. This solution was then evaporated at three different temperatures (40, 60, or 80°C), resuspended in chloroform, and washed in deionized water at three different pH values (3.3, 5.0, or 8.5). At 40°C, the estimated 50% inhibition concentration (IC50) was 2.06, 2.19, and 8.64 mg lyophilized A. spiroides cells ml−1 for the extraction pH of 3.3, 5.0, and 8.5, respectively. At 60°C, the values were 4.82, 3.06, and 12.0 mg/ml at increasing pH values. Finally, at 80°C, the IC50 values were 3.52, 4.35, and 30.1 mg/ml at the same pH values. These results indicate that pH 3.3 and a temperature of 40°C should be employed to preserve toxin content. The optimized protocol was employed to evaluate the anticholinesterase potency of environmental samples of water containing different numbers of filaments of cyanobacterial species. Registered inhibition ranged from 5.11 to 11.1%, supporting the feasibility of the method.
Degradation of petroleum hydrocarbons in two sub-antarctic soils: Influence of an oleophilic fertilizer
Authors: Coulon Frédéric , Pelletier Emilien , Gourhant Lénaïck , Louis Richard St. , Delille Daniel 
Published: November 2004

Abstract
In order to determine the long-term effects of fertilizer on the degradation rate and the toxicity of hydrocarbons in sub-Antarctic soils contaminated by petroleum hydrocarbons, a field study was initiated in December 2000 on two different soils of the Kerguelen Islands (69°42′E, 49°19′S). The number of hydrocarbon-degrading bacteria (HDB) increased greatly after crude-oil and diesel-fuel contamination, and the fertilizer addition had a favorable effect on HDB growth and activity. Hydrocarbon-degrading bacteria counts remained high until the end of the experiment although the total hydrocarbon content in all contaminated soils was reduced to 80 to 90% of their initial value after 330 d. Degradation of n-alkanes was enhanced significantly in the presence of the fertilizer, while the degradation of polycyclic aromatic hydrocarbons (PAHs) was only barely enhanced. Toxicity results showed a noticeable reduction with time, although toxicity remained present and important in both soils at the end of the experiment. In addition, fertilized plots showed a toxic signal greater than unfertilized ones. Overall results clearly show that fertilizer addition improves the rate of degradation of both oil contaminants. However, remaining toxic residues may constitute a drawback of the fertilizer-assisted biodegradation process at low temperatures.
Temperature effects on very slow desorption of native chlorobenzenes from sediment to water
Authors: ten Hulscher Th. E. M. , Vrind Bea A. , van Noort Paul C. M. , Govers Harrie A. J. 
Published: November 2004

Abstract
The temperature dependence of the kinetics of very slow desorption of eight chlorobenzenes was studied in laboratory batch experiments on a field-contaminated sediment from Lake Ketelmeer, The Netherlands. The observed rate constants for very slow desorption averaged (1.5 ± 0.4) × 10−4/h at 10°C, (2.9 ± 1.0) × 10−4/h at 20°C, (5.8 ± 2.4) × 10−4/h at 35°C, and (6.4 ± 3.0) × 10−4/h at 45°C over all eight compounds. Activation energies for desorption to water were close to the enthalpy for dissolution of the pure solid in water. The activation energies ranged from 18 to 53 kJ/mol with an average of 36 ± 11 kJ/mol. These values confirm earlier reported activation energies for very slow desorption to water. They are much less than values for activation energies for desorption to the gas phase. That difference can be explained in terms of rate limiting desorption from carbonaceous adsorption sites.
Toxicity of binary mixtures of cadmium-copper and carbendazim-copper to the nematode Caenorhabditis elegans
Authors: Jonker Martijs J. , Piskiewicz Anna M. , Castellà Núria Ivorra I , Kammenga Jan E. 
Published: November 2004

Abstract
For ecological risk assessment, the additive model may be used to empirically predict toxic mixture effects. Detailed toxicity tests were performed to determine whether effects of mixtures of copper-cadmium and copper-carbendazim on Caenorhabditis elegans were similar to the effects of the individual compounds. Effects on the course of reproduction, the length of the juvenile period, the length of the reproductive period, and body length were analyzed. Dose–response data were compared to the additive model and tested for four deviation patterns from additivity: No deviation, synergistic/antagonistic deviation, dose ratio-dependent deviation, dose level-dependent deviation. During the exposure, the cadmium-copper effect on reproduction changed from a synergistic, to a dose ratio-dependent deviation from additivity. More cadmium in the mixture decreased the toxicity and more copper increased the toxicity. The effect of copper-carbendazim on reproduction was synergistic at low dose levels and antagonistic at high dose levels and independent of time. Mixture effects on the juvenile and reproductive period were similar to single component effects. It was concluded that the observed time-dependence of toxic interactions was small and that interactions on the timing of reproduction were not found. The additive model underestimated mixture effects on reproduction and body length.
Differential tolerance among cryptic species: A potential cause of pollutant-related reductions in genetic diversity
Authors: Rocha-Olivares Axayácatl , Fleeger John W. , Foltz David W. 
Published: November 2004

Abstract
Differential mortality of cryptic species (i.e., morphologically similar but genetically distinct sibling species) may contribute to observed reductions in genetic diversity at contaminated sites if the members of a complex of cryptic species exhibit differential responses to the contaminants that are present. We conducted toxicity bioassays with both polynuclear aromatic hydrocarbon and metal contamination on Cletocamptus fourchensis and C. stimpsoni from two intensively sampled locations. Previous molecular and detailed morphological analyses segregated these as cryptic species from the cosmopolitan C. deitersi. We found that these species occur together at two field sites and that they exhibit unique toxic responses to heavy metals, suggesting differential tolerances at contaminated sites. These findings suggest that reported losses of genetic diversity at contaminated sites may represent a reduction in species diversity rather than a loss of the presumed less-tolerant genotypes within a species. They also suggest that members of a cryptic species complex should not be used in laboratory toxicity tests unless populations are genetically characterized. Future studies using genetic diversity as a marker of contaminant effects should consider the possibility of undetected cryptic species.
Arsenic speciation in tissues of the mediterranean polychaete Sabella spallanzanii
Authors: Fattorini Daniele , Regoli Francesco 
Published: November 2004

Abstract
Arsenic toxicity is strictly related to its chemical form and marine organisms are known to accumulate this element mostly as organoarsenic nontoxic molecules. Contrasting with this general trend, the presence of moderately toxic to toxic arsenic compounds recently has been reported in some polychaete species, showing a completely different profile of represented chemical species. In this work the presence and distribution of arsenic were characterized in the Mediterranean polychaete Sabella spallanzanii, by analyzing total levels in different tissues and subcellular fractions and the occurrence of various arsenical compounds. Further investigations on arsenic accumulation in S. spallanzanii were based on the capability of this species to regenerate the branchial crown both in laboratory and field conditions. Though basal levels of arsenic in the thorax were similar to those already described for most polychaetes and invertebrate species, branchial crown revealed a remarkable accumulation of this element with concentrations higher than 1,000 μg/g. Arsenic mainly was localized in a soluble form within the cytosol and dimethyl-arsinate (DMA) appeared the most represented chemical species. Experiments on bioaccumulation of arsenic in regenerating branchial crowns confirmed the environmental origin of this element and the time-dependent appearance of various As compounds suggested a methylation pathway more than a degradation process for the elevated content of DMA. The accumulation of this moderately toxic compound in the more vulnerable tissues of the polychaete might represent an antipredatory strategy, as indicated by some feeding trials where fish ate the thorax but rejected the branchial crowns.
Polycyclic aromatic hydrocarbons in a highly industrialized urban estuary: Inventories and trends
Authors: Walker Shelby E. , Dickhut Rebecca M. , Chisholm-Brause Catherine 
Published: November 2004

Abstract
The abundance and composition of polycyclic aromatic hydrocarbons (PAHs) in sediments of the main stem and southern branch of the Elizabeth River (VA, USA), a highly industrialized urban estuary in the Chesapeake Bay (USA) watershed, were examined relative to historical and toxic effects levels. Total PAH concentrations in Elizabeth River sediments exceeded those observed in Baltimore Harbor and the Anacostia River, two other regions of concern in the Chesapeake Bay. The ΣPAH concentrations from samples collected in the vicinity of two former wood-treatment facilities in the Elizabeth River had the highest ΣPAH when compared to coastal and estuarine systems around the world. Using a linearized diffusion model equation, as much as 69% of the variability in channel sediment ΣPAH distribution could be ascribed to inputs associated with former wood-treatment facilities along the southern branch of the Elizabeth River. Comparison of PAH levels measured in channel samples to data collected during the early 1980s demonstrated a general trend toward reduction in contaminant concentrations for most regions of the Elizabeth River channel; however, steady-state and increased sediment PAH concentrations in the vicinity of the former wood-treatment facilities were observed. Based on examination of the contaminant levels in Elizabeth River sediments using established sediment-quality criteria, the southern branch of the river remains a clear hazard to benthic and pelagic organisms.
Feminization of female leukophore-free strain of Japanese medaka (Oryzias latipes) exposed to 17β-estradiol
Authors: Balch Gordon C. , Shami Karmi , Wilson Paul J. , Wakamatsu Yuko , Metcalfe Chris D. 
Published: November 2004

Abstract
The recently developed female leukophore-free (FLFII) strain of Japanese medaka (Oryzias latipes) carries DNA markers for the identification of genotypic sex. Information regarding genotypic sex is useful for tests in which endocrine-disrupting compounds may masculinize or feminize fish. In the present study, methods were developed to automate DNA extraction and profiling for rapid determination of genotypic sex. Adequate amounts of DNA were isolated by robotic extraction procedures from the caudal fin. New primers were developed to include an 18-base pair segment that is in the × chromosome of female medaka but is absent in the Y chromosome of male medaka. Automated profiling methods with 96-well plates permitted analysis of the genomic sex of medaka at rates of up to 500 fish/d. We investigated the sensitivity of the FLFII strain to the feminizing effects of the potent estrogen 17β-estradiol (E2), and we compared this sensitivity to that of a wild strain that has been used widely in the study of endocrine-disrupting compounds. All FLFII medaka exposed to 1 μg/L of E2 (n = 50) had the female gonadal phenotype (i.e., ovaries), and all but one wild-strain medaka exposed to 1 μg/L of E2 (i.e., 47 of 48 fish) had the female gonadal phenotype, indicating that the FLFII and wild strains have approximately equal sensitivities to the feminizing effects of E2. Analysis of the genotype of FLFII medaka confirmed that 100% of fish with the male genotype had been feminized to the female gonadal phenotype. The FLFII strain is an excellent teleost model for detecting feminization or masculinization of fish, and automated methods can be used for rapid analysis of the genotypic sex of FLFII medaka.
Highly persistent butyltins in northern marine sediments: A long-term threat for the Saguenay Fjord (Canada)
Authors: Viglino Liza , Pelletier Émilien , St.-Louis Richard 
Published: November 2004

Abstract
An exhaustive study of the distribution of butyltin species was conducted in the sediment of the Saguenay Fjord (Canada), a semi-enclosed marine system with sediment permanently submitted to sub-Arctic cold conditions. Concentrations of total butyltins (tributyltin [TBT], dibutyltin, and monobutyltin) ranged from 6 to 288 ng Sn/g dry weight and were typical of those reported for contaminated coastal areas despite limited seasonal traffic of commercial vessels in the fjord. The distribution profiles of butyltin species in four sediment cores clearly indicated the high persistence of TBT that was dominating other species. The particular oceanographic conditions of the Saguenay Fjord (low seawater temperature, anoxic sediments, and low exchange rate of deep waters) combined with a high sediment/pore-water partition coefficient (Kdobs = 1.0 × 104 to 1.2 × 104 L/kg) and a low sediment/water diffusive flux of TBT (J1 = 13 × 10−8 mol/m2/year) are responsible for the burial and preservation of TBT in this marine ecosystem. The half-life of TBT in deep sediment was estimated to be approximately 87 ± 17 years (± SEM), which implies a much slower degradation rate than any previously reported. Finally, a flood event that occurred five years before the sampling enabled us to calculate a very slow diffusive flux from the preflood to the postflood layer (J2 = 2 × 10−8 mol/m2/year), indicating an almost permanent sequestration of TBT in the buried layers.
Physicochemical and toxicological studies on 4-chloro-3,5-dinitrobenzoic acid in aqueous solutions
Authors: Lopez Jorge L. , Einschlag Fernando S. García , Rives Carina V. , Villata Laura S. , Capparelli Alberto L. 
Published: November 2004

Abstract
Physicochemical characterization of hazardous compounds often is required for the development of structure-reactivity correlations. Physical, chemical, and toxicological properties of target pollutants require determination for an efficient application of wastewater treatments. In the present work, we chose a chloro-nitro-aromatic derivative (4-chloro-3,5-dinitrobenzoic acid [CDNBA]), as a model compound on which to perform physicochemical and toxicological studies. Several properties of CDNBA are not available in the literature, although many aromatic nitro-compounds are considered hazardous materials. Measurements of solubility in water, acid dissociation constant, and kinetic parameters for the nucleophilic substitution of chlorine atom in alkaline media are reported. We also performed cytotoxicity studies of CDNBA and ultraviolet-irradiated CDNBA solutions. From the analysis of CDNBA solubility in water at different temperatures, an enthalpy of solution of 23.2 ± 2.5 kJ/mol was found. The study of the acid dissociation constant Kc by using conductivity measurements and the modified Gran's method yielded values for the equilibrium constant Ka of 2.36 × 10−3 and 2.26 × 10−3, respectively. The bimolecular rate constant for the reaction of CDNB− and hydroxyl ion (HO−) measured at room temperature and 0.1 M of ionic strength was 5.92/M·s, and the activation energy for this process was 70.7 ± 3.4 kJ/mol. Cytotoxicity assays with aqueous suspensions of Tetrahymenapyriformis showed lethal effects due to the pH change induced by CDNBA. On the other hand, in buffered solutions, a value of 104.47 μM was observed for the median effective concentration, that is, the concentration of CDNBA at which the proliferation was restricted to one half of the blank. Irradiation of CDNBA solutions increased the toxicity, suggesting the formation of intermediate products with higher cytotoxicity effects.
Aquatic risk assessment of a realistic exposure to pesticides used in bulb crops: A microcosm study
Authors: van Wijngaarden René P.A. , Cuppen Jan G.M. , Arts Gertie H.P. , Crum Steven J.H. , van den Hoorn Martin W. , van den Brink Paul J. , Brock Theo C.M. 
Published: November 2004

Abstract
The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metamitron were applied to indoor freshwater microcosms (water volume approximately 0.6 m3). The treatment regime was based on a realistic application scenario in tulip cultivation. Concentrations of each pesticide were equal to 0%, 0.2%, 0.5%, 2%, and 5% spray drift emission of label-recommended rates. Contribution of compounds to the toxicity of the pesticide package was established by expressing their concentrations as fractions of toxic units. The fate of the compounds in the water, and responses of phytoplankton, zooplankton, periphyton, macroinvertebrates, macrophytes, decomposition, and water quality were followed for 13 weeks. The half-lives of lambda-cyhalothrin, metamitron, and fluazinam were 1 to 2 d; that of asulam was &gt;30d. No consistent effects could be demonstrated for the 0.2% treatment regime that was therefore considered the no-observed-effect concentrationcommunity (NOEC). The macroinvertebrate populations of Gammarus pulex, Asellus aquaticus, and Proasellus meridianus were the most sensitive end points, followed by species of copepods and cladocerans. Responses mainly were due to lambda-cyhalothrin. The 0.5% treatment regime resulted in short-term effects. Pronounced effects were observed at the 2% and 5% treatment levels. At the end of the experiment, the macrophyte biomass that consisted of Elodea nuttallii, showed a decline at the two highest treatment levels, asulam being the causal factor (NOEC: 0.5% treatment level). Primary production was reduced at the 5% treatment level only. In our experiment, the first-tier risk assessment procedure for individual compounds was adequate for protecting sensitive populations exposed to realistic combinations of pesticides. Spray drift reduction measures seem to be efficient in protecting aquatic ecosystems in agricultural areas.
Fitness cost of resistance to cadmium in the least killifish (Heterandria formosa)
Authors: Xie Lingtian , Klerks Paul L. 
Published: November 2004

Abstract
Fitness costs constrain the evolution of resistance to environmental stress in populations. We earlier reported on a rapid response to laboratory selection for cadmium resistance in the least killifish (Heterandria formosa). By the sixth generation, the three selection populations were threefold more resistant to cadmium than the control populations. Here, we report the fitness costs and trade-offs associated with this evolution of resistance. In the F3 and F4 generations, the selection populations produced smaller-sized offspring than the control populations. A comprehensive life-history traits study in the F7 generation showed that the selection populations had, on average, an 18% decrease in fecundity. The selection populations also had a smaller brood size, longer time to first reproduction, and shorter female life expectancy than the control populations. Our results strongly suggest that fitness costs and trade-offs were associated with the evolution of resistance to cadmium in the least killifish. The fitness costs and trade-offs may result from maintenance of the underlying resistance mechanisms, leading to changes in resource allocation in the cadmium-adapted fish.