bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased cadmium excretion in metal-adapted populations of the midge Chironomus riparius (diptera)
Authors: Postma Jaap F. , VanNugteren Paul , De Jong Marion B. Buckert- 
Published: March 2010

Abstract
Cadmium kinetics were studied in cadmium-adapted and nonadapted field populations of the midge Chironomus riparius. Accumulation and elimination experiments were carried out using first-generation laboratory-reared animals. Differences between populations were, therefore, assumed to have a genetic basis. Larvae were dissected to analyze the guts and the remainder of the larvae separately. First-order one-compartment models were not always successful in describing accumulation processes, probably due to acclimation. No interpopulation differences were observed in larval development based on dry weights, whereas some differences existed based on pupation rate. In most cases more than 80% of the total amount of cadmium was found in the guts of all populations. Larvae from cadmium-adapted populations showed a decreased net accumulation rate as well as higher equilibrium values (15–20%) compared to nonadapted populations. In addition, cadmium excretion efficiency was increased for cadmium-adapted larvae, which was due to an increased elimination rate from the guts. It was concluded that exposure to high cadmium concentrations in the field resulted in populations of C. riparius with an increased storage capability and an increased excretion efficiency, especially regarding the guts.
Accumulation and depuration of resin acids and fichtelite by the freshwater mussel Hyridella menziesi
Authors: Burggraaf Shane , Langdon Alan G. , Wilkins Alistair L. , Roper David S. 
Published: March 2010

Abstract
Freshwater mussels incubated in the effluent of a kraft pulp and paper mill rapidly accumulated resin acids and fichtelite in their tissues, approaching a steady state in 7 d or less. Mean bioconcentration factors (BCFs) for individual resin acids varied from 110 to 330 L/kg dry wt. for 14-chlorodehydroabietic acid and abietic acid, respectively. The mean BCF for fichtelite was 4,900 L/kg dry wt., at least an order of magnitude greater than that of the resin acids. Resin acids were depurated rapidly from mussel tissue (biological half-lives of 3 d), whereas fichtelite concentrations declined more slowly (biological half-life 12 d). Depuration kinetics for these compounds appeared to be described by a first-order process. The possibility that the uptake process for fichtelite is zero order is explored.
Effects of water pH on copper toxicity to early life stages of the common carp (Cyprinus carpio)
Authors: Stouthart Xander J. H. X. , Haans Jeroen L. M. , Lock Robert A. C. , Bonga Sjoerd E. Wendelaar 
Published: March 2010

Abstract
Carp eggs were exposed immediately after fertilization to Cu concentrations of 0.3 and 0.8 μmol/L at water pH 7.6 or pH 6.3. Mortality, the incidence of spinal cord deformation, heart rate, tail movements, hatching success, and whole-body content of K, Na, Mg, Ca, and Cu were determined over time. Light microscopical preparations of eggs (48 h after fertilization) and larvae (168 h after fertilization) were studied. At pH 7.6, Cu did not affect egg mortality, heart rate, tail movements, and whole-body K and Mg content. Hatching success increased only in the 0.3 μmol/L Cu group. Exposure to 0.8 μmol/L Cu increased larval mortality and larval deformation and decreased whole-body Na and Ca content. At pH 6.3, exposure to 0.8 μmol/L Cu increased egg mortality and decreased heart rate and tail movements. Furthermore, premature hatching, a concentration-dependent increase of larval mortality, and larval deformation was observed. Exposure to 0.3 and 0.8 μmol/L Cu decreased the whole-body content of K, Na, Mg, and Ca. Uptake of Cu after hatching increased two-fold at pH 6.3 compared to the pH 7.6 groups. At pH 6.3, all Cu-exposed larvae were unable to fill their swim bladder. Also, after 168 h the yolk sac remained largely unabsorbed in the 0.3 and 0.8 μmol/L Cu group. Exposure to 0.8 μmol/L Cu resulted in coagulation of proteins in eggs and yolk sacs. No significant changes in any of the assessed parameters were observed in control groups of pH 6.3 and pH 7.6.
Modeling dose response using generalized linear models
Authors: Kerr David R. , Meador James P. 
Published: March 2010

AbstractThis paper describes a method to determine and model dose–response relationships from binomial response data using generalized linear models (GLM). The main advantage of this technique is that it allows LCp or LDp to be determined without an initial linearizing transformation. (LCp and LDp are the lethal concentration or dose that causes p proportion of test animals to die at a specified time period.) Thus, the method of GLM is an appropriate way to analyze a dose–response relationship because it utilizes the inherent S-shaped feature of the toxicologic response and incorporates the sample size of each trial in parameter estimation. This method is also much better behaved when the extremes of the response probability are considered because responses of 0% and 100% are included in the model. Another advantageous feature of this method is that confidence intervals (C.I.s) for both the dose estimate and response probabilities can be computed with GLM, which provides a more complete description of the estimates and their inherent uncertainty. Because C.I.s for both the dose estimate and response probabilities can be constructed, the lowest observed effect concentration (LOEC) can also be determined.
Toxicokinetics-based survival analysis in bioassays using nonpersistent chemicals
Authors: Widianarko Budi , VanStraalen Nico 
Published: March 2010

Abstract
Present statistical analysis of survivorship data obtained from bioassays using nonpersistent toxicants does not explicitly take into account that exposure decreases with time due to degradation of the toxicant. Such a situation typically occurs in static aquatic toxicity tests and in soil tests. We develop a model for the analysis of survival data obtained in such experiments and show how estimates for the initial LC50, the degradation rate constant, and the elimination rate constant may be obtained from observations on time-dependent survival rates. The model assumes linear one-compartment toxicokinetics with exponentially decreasing input. The probability of dying is assumed to be directly proportional to the internal concentration. An explicit expression for time- and concentration-dependent survival is obtained. The model predicts that, with increasing exposure time, survival will approach a nonzero baseline value for certain initial concentrations. Application of the model is illustrated by curve-fitting to experimental observations, made over 6 weeks, for the effect of diazinon on the terrestrial isopod Porcellio scaber. The fit to data is fairly good, but the parameter estimates tend to have a high coefficient of variation. A considerable increase of precision may be obtained if the degradation rate constant is given a fixed value (for example, following from chemical residue analysis of the medium). The approach is applicable to all situations where, due to loss of the toxicant during the test, mortality shows no further increase after a certain exposure period.
Evaluating risk predictions at population and community levels in pesticide registration-hypotheses to be tested
Authors: Kapustka Lawrence A. , Williams Bill A. , Fairbrother Anne 
Published: March 2010

Abstract
Chemical registrations under FIFRA (Federal Insecticide, Fungicide, and Rodenticide Act) and TSCA (Toxic Substance Control Act) in the United States, and equivalent regulations in Canada and Europe, are driven extensively by risk assessments. Chemicals intended for use as pesticides are evaluated by considering fate and transport, toxicity, and assumed exposure scenarios. For nonpesticide chemicals, very limited testing information is generated to support the risk management decisions. Despite the restricted quantity of information, risk-based predictions are intended to provide analyses that are adequate to evaluate ecological safety margins. Persistent questions regarding adequacy of protection have dogged risk assessors, regulators, and registrants. From a scientific perspective, risk assessments are essentially complex hypotheses, not conclusive or factual statements. Given the great reliance on extrapolations from individual-based toxicity (and generally poor exposure characterizations) to statements of community, ecosystem, landscape, regional, and even global levels of organization, it is perhaps remarkable that the system has worked at all. But do we really know if the system works? If we wish to retain a scientific basis in registration, follow-up work that tests the risk-prediction hypotheses needs to be done. Properly structured around testable parameters, focused monitoring programs could reduce much of the mystery embodied in current practice. Greater reliance on monitoring data to test risk predictions could reduce the tendency to concatenate uncertainty factors that unnecessarily expand Type II errors. We propose changes in the registration process to address these concerns.
Interactions of Cd and Cu in anaerobic estuarine sediments. I. Partitioning in geochemical fractions of sediments
Authors: Rule Joseph H. , Alden Raymond W. 
Published: March 2010

Abstract
Partitioning of Cd and Cu between geochemical fractions of an a aerobic estuarine sediment was determined after equilibrating fine-sandy sediment with different combinations of added Cd (0, 2.5, 5 mg/kg) and Cu (0, 12.5, 25 mg/kg). Sediments were placed in aquaria with 20 ppt seawater where bioassay test organisms were exposed for 14 d. At the start and conclusion of the experimental period, sediments were sequentially extracted to determine the elemental content of the exchangeable (EP), easily reducible (ERP), organic-sulfide (OSP), moderately reducible (MRP), and acid extractable (AEP) phases. Partitioning of the metals in both the native and treated sediments was, for Cd: OSP ≫ ERP &gt; AEP &gt; EP (MRP was below detection) and for Cu: OSP ≫ AEP &gt; ERP &gt; MRP &gt; EP. Cadmium extracted in all phases and Cu in the EP, ERP, and OSP were proportional to the respective treatments. The EP-Cd, ERP-Cd, and OSP-Cd were affected by the Cu treatment and significant interactions occurred between Cd and Cu for the EP-Cd, ERP-Cd, OSP-Cd, EP-Cu, and ERP-Cu. Increasing levels of applied Cd and Cu resulted in greater amounts of EP-Cd and ERP-Cd, fractions that are the most bioavailable and the most readily available for desorption into the water column. A significant conclusion is that the input of nontoxic metals may affect the geochemical phase distribution, potential bioavailability, and toxicity of native sediment metals.
Biodegradation of triethanolamine
Authors: West Robert J. , Gonsior Stanley J. 
Published: March 2010

Abstract
Triethanolamine production in the United States exceeds 100,000 metric tons per year. Given this magnitude of production and widespread distribution to consumer product, specialty chemical, and agricultural chemical markets, an understanding of the environmental fate and lifetime of this chemical is warranted. Studies were conducted to determine the fate and lifetime of [14C]triethanolamine in an aerobic surface soil, freshwater river systems, and in activated sludge waste treatment. The half-life determined for biodegradation of triethanolamine ranged from 0.02 to 0.10 d in reactions containing 818 mg/L mixed liquor activated sludge solids from a municipal wastewater treatment facility. The half-life of triethanolamine in a sandy loam surface soil ranged from 0.5 to 1.8 d for initial concentrations ranging from 0.01 to 13.4 mmol/kg (1.4–2,000 mg/kg dry wt). Biodegradation was also measured in two different river waters, with an average half-life (±1 SD) of 1.2 ± 0.5 d determined for initial triethanolamine concentrations of 0.67 and 3.28 μmol/L (99 and 489 μg/L). The kinetics of both primary biodegradation and mineralization were shown to be generally first-order in triethanolamine and biomass concentrations (second-order overall) for the matrices and range of triethanolamine concentrations tested. When these relatively short half-lives are related to typical chemical residence times in various environmental compartments, it can be concluded that biodegradation would prevent accumulation of triethanolamine and its associated degradation products in the environment.
Persistence of herbicide residues in Gammarus lacustris (crustacea: Amphipoda) in Prairie wetlands
Authors: Arts Michael T. , Headley John V. , Peru Kerry M. 
Published: March 2010

Abstract
Tandem mass spectrometry (MS) was used to detect herbicide residues in wild populations of amphipods collected from microcosms spiked with a single pulse of either Avadex®-BW (triallate) or HoeGrass® (diclofop-methyl) at three different concentrations (1.0, 10.0, and 100.0 μg·L−1). Independent confirmations of both herbicides were obtained by spiking amphipod tissues with 50 pg of authentic standards of triallate or diclofop-acid. The in situ microcosm experiments demonstrated that positive confirmation of triallate could still be made 30 d following an initial single spike of 10 μg·L1 triallate. Diclofop-acid could still be detected in lipid-rich tissues of amphipods 10 and 15 d following an initial spike concentration of 10 and 100 μg·L1, respectively. The chief advantages of tandem MS include the ability to analyze small quantities of tissue (&lt;1 mg wet weight), the ability to detect picogram levels of target analytes, and user flexibility in the choice of tissue to be analyzed (e.g., lipid-rich storage tissue, muscle, nervous tissue, etc.).
Uptake of chlorobenzenes by tissues of the soybean plant: Equilibria and kinetics
Authors: Tam Deborah D. , Shiu Wan-Ying , Qiang Kang , Mackay Donald 
Published: March 2010

Abstract
Measurements are reported of the uptake equilibria and kinetics of seven chlorobenzenes: 1,2–dichlorobenzene, 1,3–di-chlorobenzene, 1,2,4–trichlorobenzene, 1,2,3,4–tetrachlorobenzene, 1,2,3,5–tetrachlorobenzene, pentachlorobenzene, and hexachloro-benzene from water into tissues (leaves, petioles, stems, and roots) of 6–8–week-old soybean plants, Glycine max L. Equilibrium was reached within 1–4 days, with uptake of the more hydrophobic chemicals being slightly slower. Aqueous solubilities of three of these chlorobenzenes are reported. Linear correlations were obtained between the equilibrium tissue-water partition coefficients, the chemicals' octanol-water partition coefficients and the measured lipid contents. A correlation approach is proposed that may be useful for assessment of the extent of uptake of persistent hydrophobic chemicals by plants from soil and the atmosphere.
Monitoring the effects of five “nonherbicidal” pesticide chemicals on terrestrial plants using chlorophyll fluorescence
Authors: Rugh Brent W. K. , Miles Donald 
Published: March 2010

Abstract
This experiment was carried out in anefforttodetermine if several commonly encountered “nonherbicidal” pesticides can affect the photosynthetic electron transport capacity of plants, and if so, can the effects caused by these pesticides be detected by chlorophyll fluorescence induction analysis. The study involved the incubation of excised leaves of mung beans (Phaseolus vulgaris L.) in five pesticidal chemicals: carbofuran, tributyltin chloride, chlorpyrifos, phorate, and fonofos. Diuron, a well-known inhibitor of photosynthesis was used as a positive control. Following chlorophyll fluorescence induction analysis of the mung bean leaf cuttings, the Fv /Fm and Fq parameters (a measure of the quantum efficiency and the fluorescence quenching capacity, respectively) were analyzed. Diuron dramatically decreased the Fv /Fm and the F values of the mung bean leaf cuttings following 2 h exposure to concentrations as low as 2.0 μM. Phorate also caused a significant decrease in the Fv /Fm values of mung bean leaf cuttings; however, the decrease was considerably less than that caused by diuron and did not appear until the treatment concentration reached 200 μM. There was no apparent change in the Fv /Fm values of the mung bean leaf cuttings treated with the other pesticidal chemicals. Both phorate and tributyltin chloride caused decreases in the Fq values of mung bean leaf cuttings though not as dramatic as the decreases from diuron treatment. The decreases in the fluorescence quenching capacity of mung bean leaf cuttings occurred with exposure to 20 μM tributyltin chloride but not until exposure to 200 μM of phorate. These results indicate that some nonherbicidal pesticides can adversely affect certain species of plants and that chlorophyll fluorescence induction analysis can be used to detect these effects.
Degradation of 3,5-dimethyl-tetrahydro-2H-1,3,5-thiadiazine-2-thione in aqueous aerobic media
Authors: Subramanian Periyasamy , Teesch Lynn , Thorne Peter S. 
Published: March 2010

Abstract
Decomposition of 3,5-dimethyl-tetrahydro-2H-1,3,5-thiadiazine-2-thione (DTTT) has been studied by UV-visible spectroscopy (UV-VIS), high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and fast atom bombardment-mass spectrometry (FAB-MS). Hydrolysis rate constants for DTTT and rate constants for product formation were measured. The partially hydrolyzed and aged DTTT solutions have been separated and analyzed by GC-MS. Formaldehyde, 1,3-dimethyl-2-thiourea, N -methyl dithiocarbamic methyl ester, N -methyldithiocarbamic perthiomethyl ester, 2-methyl-5-dihydro-3H-4-thia-1,2-isooxazolidine-3-thione, 1,3,5-trimethyl-hexahydro-2H-1,3,5-triazine-2-thione, 4-methyl-5-methylimino-1,2,4-dithiazolidine-3-thi-one, and 2,4-dimethyl-1,2,4-thiadiazolidine-3,5-dithione were identified from the hydrolyzed DTTT solution. Methyl isothiocyanate, which is one of the intermediates formed during the decomposition of DTTT, was also monitored by UV-VIS and HPLC for the formation of common products and characterized by GC-MS. The decomposition pathways for DTTT are presented and are in accord with the limited literature data. Environmental impact assessment of the DTTT and its metabolites is summarized.
Effects of grasshopper-control insecticides on survival and brain acetylcholinesterase of pheasant (Phasianus colchicus) chicks
Authors: Martin Pamela A. , Ohnson Daniel L. J. , Forsyth Douglas J. 
Published: March 2010

AbstractRing-necked pheasant (Phasianus colchicus) chicks were exposed via contact and/or ingestion to formulations of three insecticides (Lorsban 4E, chlorpyrifos; Cygon 480E, dimethoate; and Furadan 480F, carbofuran) applied to pasture plots at one and four times the rate recommended for control of grasshoppers (Orthoptera: Acrididae) in prairie Canada. Chicks (3 d old) were exposed for 48 h in pens with the sprayed vegetation and were fed either unsprayed grasshoppers or grasshoppers sprayed at the same rates as the vegetation. Control groups were exposed to unsprayed vegetation and received unsprayed grasshoppers. Three replicates were conducted throughout June and early July 1992.Although some signs of acetylcholinesterase (AChE) depression were observed in chicks exposed to insecticides, there was no difference in the number of mortalities among treatment and control groups. Chicks that died during the exposure period gained significantly less weight than survivors in all groups. Among surviving chicks, weight gains of those exposed to the high- rate Furadan treatment consuming sprayed food were significantly lower than those of controls (1.8 vs. 6.6 g/d). Brain AChE activity was lower overall in surviving chicks than in those that died; it was not significantly reduced among chicks that died in any treatment group. Overall, survivors of Furadan- exposed treatment regimes had lower AChE activity than those of Cygon and Lorsban treatments; birds in high-spray-rate treatments of all insecticides had lower AChE activity than those in all low-spray-rate treatments; and birds in all treatments consuming sprayed grasshoppers had lower AChE activity than those fed unsprayed grasshoppers. Food consumption was not affected by any treatment.
Synergy between deltamethrin and prochloraz in bees: Modeling approach
Authors: Chalvet-Monfray Karine , Sabatier Philippe , Belzunces Luc P. , Colin Marc E. , Fléché Cécile 
Published: March 2010

Abstract
The metabolic hypothesis proposes that the fungicide prochlorazacts synergistically on deltamethrin by inhibiting oxidative metabolism of deltamethrin. The limits of validity of this hypothesis were tested using a pharmacokinetic box model. Experimental work showed that bee mortalities were higher after 2 h in groups sprayed with deltamethrin at 0.25 g-ha−1 in the presence of prochloraz (25 g-ha−1) than in those sprayed at 1 g-ha−1 with deltamethrin alone. We defined t as the time at which the internal concentration of deltamethrin is the same for both treatments. For the metabolic hypothesis to be consistent with experimental results, t must be less than 2 h. Given t &lt; 2 h, the model was used to study pharmacokinetic parameter values. Published parameter values were inconsistent with simulation results because in all cases t was greater than 2 h. Consequently, the synergy between prochloraz and deltamethrin cannot be explained by the inhibition of oxidative metabolism.
Neogastropod imposex for monitoring recovery from marine tbt contamination
Authors: Tester Monica , Ellis Derek V. , Thompson J. A. Jeffrey 
Published: March 2010

Abstract
Imposex, the imposition of male sexual characters on female snails, was used as a bioindicator of recovery from tributyltin (TBT) pollution in the Pacific Northwest. Whelks surveyed before TBT use was regulated had shown a high frequency of affected females in the Strait of Juan de Fuca and the Strait of Georgia; and lower frequency on the west coast of Vancouver Island. A reduction in imposex is now evident on the west coast of Vancouver Island and in some locations in the Strait of Georgia. There is no clear evidence of recovery near Victoria, and Vancouver Harbour still does not have whelks in any abundance, if at all. Of the four species studied, Nucella emarginata is the most suitable bioindicator species because it is abundantly distributed and has the shortest lifespan (1–2 years). When frequency of imposex remains at 100%, the FPL (female penis length) is still available as a useful bioindicator.
Effects of diazinon on large outdoor pond microcosms
Authors: Giddings Jeffrey M. , Biever Ronald C. , Annunziato Maria F. , Hosmer Alan J. 
Published: March 2010

Abstract
An aquatic microcosm study (simulated aquatic field study) was conducted with the technical grade of the organophosphorus insecticide diazinon. Eighteen fiberglass tanks, each 3.2 m in diameter and 1.5 m in depth, were established with sediment and water (11.2 m3) from natural ponds and stocked with 40 juvenile bluegill sunfish (Lepomis macrochirus). Diazinon was applied in aqueous solution three times at 7-d intervals. Eight loading rates were used, with two microcosms at each level plus two controls. The amounts of diazinon added during each application corresponded to theoretical concentrations from 2.0 μg/L to 500 μg/L. The most sensitive ecological components of the microcosms were Cladocera (zooplankton), and Pentaneurini and Ceratopogonidae (insects), which were reduced at all treatment levels. Effects on many zooplankton and macroinvertebrate taxa occurred at diazinon concentrations (time-weighted averages) of 9.2 μg/L and higher. Total fish biomass was reduced at 22 μg/L and higher, and fish survival was reduced at 54 μg/L and higher. Odonates, some dipterans, and plants were not adversely affected by diazinon at 443 μg/L, the highest concentration tested. Microcosm results were consistent with laboratory toxicity data for some taxa (e.g., cladocerans, Ephemeroptera, and bluegill sunfish), but differed substantially for others (e.g., rotifers, Chironomini, and odonates). The no-observed-effect concentration (NOEC) in the microcosms (70-d time-weighted average) was near the 10th percentile of single-species LC50 values.