bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of soil sorption coefficient of organic pesticides from the atom-type electrotopological state indices
Authors: Huuskonen Jarmo 
Published: March 2010

AbstractA group contribution approach based on atom-type electrotopological state indices for predicting the soil sorption coefficient (log KOC) of a diverse set of 201 organic pesticides is presented. Using a training set of 143 compounds, for which the log KOC values were in the range from 0.42 to 5.31, multiple linear regression (MLR) and artificial neural networks were used to build the models. The models were validated using two test sets of 20 and 38 chemicals not included in the training set. The statistics for a linear model with 12 structural parameters were, in test set 1, r2 = 0.79, s = 0.45 and, in test set 2, r2 = 0.74, s = 0.65. These results clearly show that soil sorption coefficients can be accurately and rapidly estimated from easily calculated structural parameters.
Induction of CYP1A by the N-imidazole derivative, 1-benzylimidazole
Authors: Navas José María , Chana Antonio , Herradón Bernardo , Segner Helmut 
Published: March 2010

Abstract
Xenobiotics can induce cytochrome P4501A (CYP1A) by ligand binding to the aryl hydrocarbon receptor (AhR). Typical AhR ligands are polycyclic aromatic compounds with planar molecular conformation. The present work investigated the ability of the N-imidazole derivative, 1-benzylimidazole (BIM), to induce CYP1A in rainbow trout hepatocytes. Benzylimidazole increased hepatocellular CYP1A catalytic activity (determined as 7-ethoxyresorufin-O-deethylase [EROD] activity) and CYP1A mRNA in a concentration-dependent way. Computational studies on the molecular structure of BIM indicated that the energetically most stable BIM conformer has the imidazole ring and the phenyl ring in different planes, i.e., does not take a planar conformation. This property of BIM does not agree with the structural requirements of a typical AhR ligand. In line with this observation, we found that the AhR antagonist, α-naphthoflavone (αNF), was not able to inhibit BIM induction of EROD activity and CYP1A mRNA, although it inhibited the induction of CYP1A by the prototypic AhR ligand, β-naphthoflavone (βNF). The results suggest that transcriptional activation of CYP1A by the N-imidazole derivative, BIM, is not mediated through direct ligand binding to the AhR.
The relative sensitivity of four benthic invertebrates to metals in spiked-sediment exposures and application to contaminated field sediment
Authors: Milani Danielle , Reynoldson Trefor B. , Borgmann Uwe , Kolasa Jurek 
Published: March 2010

AbstractThe relative sensitivity of four benthic invertebrates (Hyalella azteca, Chironomus riparius, Hexagenia spp., and Tubifex tubifex) was determined for Cd, Cu, and Ni in water-only and in spiked-sediment exposures. Survival (median lethal concentrations [LC50s] and the concentrations estimated to be lethal to 25% of test organisms [LC25s]), and endpoints for growth and reproduction (mean inhibitory concentrations [IC25s]) were compared. The sensitivities differed depending on the species and metal, although some trends emerged. In water-only exposures, H. azteca is the most sensitive species to cadmium and nickel, with mean LC50s of 0.013 and 3.6 mg/L, respectively; C. riparius is the most sensitive species to copper, with a mean LC50 of 0.043 mg/L. In the spiked-sediment exposures, the order in decreasing sensitivity to copper is Hyalella = Hexagenia &lt; Chironomus &lt; Tubifex for survival and growth/reproduction. For cadmium, the order in decreasing sensitivity is Hyalella = Chironomus &lt; Hexagenia &lt; Tubifex, and for nickel is Hyalella ≪ Hexagenia &lt; Chironomus &lt; Tubifex. Chironomus riparius and Hexagenia spp. survival can be used to distinguish between toxicity caused by different metals. Species test responses in field-collected sediment (Collingwood Harbour, ON, Canada) were examined in an attempt to determine the causative agent of toxicity throughout, using the established species sensitivities. Sediment toxicity was categorized first by comparing species responses to those established for a reference database. Test responses in the field-collected sediment do not support causality by Cu, a suspected toxicant based on comparison of sediment chemistry with sediment quality guidelines.
Reproductive effects of estrogenic and antiestrogenic chemicals on sheepshead minnows (Cyprinodon variegatus)
Authors: Karels Arthur Alan , Manning Steve , Brouwer Thea Hoexum , Brouwer Marius 
Published: March 2010

Abstract
Environmental estrogens can activate genes of the reproductive system, such as vitellogenin (VTG), a precursor to egg yolk protein, by activating the estrogen receptor (ER), whereas antiestrogens can inhibit ER activation. Adult lab-reared male sheepshead minnows (Cyprinodon variegatus) were exposed to estrogenic 4-tert-octylphenol (OP) and females to antiestrogenic cadmium (Cd), and the effects on four potential indicators of impaired reproductive function were examined: VTG in F0 male blood as sign of feminization, F0 generation fecundity/fertility, embryonic development/egg hatching/survival rate of F1 generation fry, and F0 gonadal histology. Mean VTG in the control, 11.5, 33.6, and 61.1 μg/L OP male fish were 0, 10.7, 38.7, and 65.6 mg/ml postexposure and 0, 2.5, 19.4, and 30.0 mg/ml postreproduction. A significant inverse relationship between increasing VTG in male blood and reproductive success of mating groups involving these males was shown, with higher OP decreasing percent viable eggs (fertility) by approximately 60%. Histology showed increased testis anomalies and decreased spermatozoa with increasing OP exposure. No effects on F1 embryonic development, egg hatching, or fry survival rate were observed. A significant decline in percent viable egg production involving Cd-exposed females occurred only when mated with OP-exposed males, with no eggs produced by fish exposed to the highest OP and Cd concentration. A three-week field exposure near a wastewater treatment plant outfall showed no elevated VTG in male plasma, but significantly higher total egg production per female per collection day (∼45%) was observed at the site furthest from the outfall.
Uptake and depuration of nonionic organic contaminants from sediment by the oligochaete,Lumbriculus variegatus
Authors: Ingersoll Christopher G. , Brunson Eric L. , Wang Ning , Dwyer F. James , Ankley Gerald T. , Mount David R. , Huckins James , Petty Jim , Landrum Peter F. 
Published: March 2010

AbstractUptake of sediment-associated contaminants by the oligochaete Lumbriculus variegatus was evaluated after 1, 3, 7, 14, 28, and 56 d of exposure to a field-collected sediment contaminated with DDT and its metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), or to a field-collected sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Depuration of contaminants by oligochaetes in a control sediment or in water was also evaluated over a 7-d period after 28 d of exposure to the field-collected sediments. Accumulation of PAHs with a log octanol-water partitioning coefficient (log Kow) &lt;5.6 typically reached a peak at day 3, followed by a lower plateau between days 7 and 56 of the sediment exposure. Similarly, 4,4′-DDT exhibited a peak in accumulation at day 14 followed by a decline at days 28 and 56. In contrast, accumulation of PAHs with a log Kow &gt;5.6 or DDD and DDE typically exhibited a steady increase from day 1 to about day 14 or 28, followed by a plateau. Therefore, exposures conducted for a minimum of 14 to 28 d better reflected steady-state concentrations for DDT and its metabolites and for PAHs. Depuration rates for DDT and its metabolites and high-Kow PAHs were much higher in organisms held in clean sediment relative to both water-only depuration and model predictions. This suggests that depuration in clean sediment may artificially accelerate depuration of hydrophobic compounds. Comparisons between laboratory-exposed L. variegatus and oligochaetes collected in the field from these sediments indicate that results of laboratory tests can be extrapolated to the field with a reasonable degree of certainty.
Effects of the herbicide imazapyr on benthic macroinvertebrates in a logged pond cypress dome
Authors: Fowlkes Mark D. , Michael Jerry L. , Crisman Thomas L. , Prenger Joseph P. 
Published: March 2010

Abstract
Increased herbicide use in silviculture over the last several decades has led to concern over potential water contamination, which may affect biotic health. In the southeastern United States, pine flatwoods are important for timber production and are often interspersed with cypress wetlands. Cypress domes are isolated, shallow basins that collect surficial waters from adjacent forested areas and therefore might be expected to contain pesticide from storm runoff. This study utilizes in situ microcosm experiments to assess the effects of a concentration gradient of the herbicide imazapyr (0.184, 1.84, and 18.4 mg/L, equivalent to 1, 10, and 100 times the expected environmental concentration from a normal application rate) on the macroinvertebrate community of a logged pond cypress dome using changes in macroinvertebrate composition, chironomid biomass, and chironomid head-capsule deformities. The control core was not significantly different from the surrounding cypress dome for any parameter, suggesting that enclosure effects were likely of minimal importance in the final experimental results. The lack of statistical difference (p &lt; 0.05) in macroinvertebrate community composition, chironomid deformity rate, and chironomid biomass between treatments suggests that imazapyr did not affect the macroinvertebrate community at the concentrations tested. Chironomid deformity rate ranged from 0.97% for imazapyr control to 4.96% for the 100× treatment, with chironomid biomass being 1.79 and 1.87 mg/L, respectively.
Estimation of potential and limits of bivalve closure response to detect contaminants: Application to cadmium
Authors: Tran Damien , Ciret Pierre , Ciutat Aurélie , Durrieu Gilles , Massabuau Jean-Charles 
Published: March 2010

AbstractBivalve closure responses to detect contaminants have often beens studied in ecotoxicology as an aquatic pollution biosensor. We present a new laboratory procedure to estimate its potential and limits for various contaminants and animal susceptible to stress. The study was performed in the Asiatic clam Corbicula fluminea and applied to cadmium. To take into account the rate of spontaneous closures, we integrated stress problems associated with fixation by a valve in common apparatus and the spontaneous rhythm associated with circadian activity to focus on conditions with the lowest probability of spontaneous closing. Moreover, we developed an original system by impedance valvometry, using light-weight impedance electrodes, to study free-ranging animals in low-stress conditions and a new analytical approach to describe valve closure behavior as a function of response time and concentration of contaminant. In C. fluminea, we show that cadmium concentrations above 50 μg/L can be detected within less than 1 h, concentrations down to 16 μg/L require 5 h of integration time, and values lower than 16 μg/L cannot be distinguished from background noise. Our procedure improved by a factor of six the cadmium sensitivity threshold reported in the literature. Problems of field applications are discussed.
A simulation study of methods for constructing confidence intervals for bioaccumulation factors
Authors: Wheeler Matthew W. , Bailer A. John 
Published: March 2010

Abstract
Toxicokinetics describe the time course of xenobiotics in an exposed organism. The steady state concentration of the xenobiotic is a characteristic of frequent concern, often summarized in terms of bioaccumulation factors (BAFs). Two experimental protocols are commonly used when estimating BAFs: a continuous exposure experiment and a start-stop exposure experiment. Nonlinear regression is then used for estimating components of the BAF. A variety of methods are available for constructing confidence intervals (CI) for the BAF, including the delta method and Fieller's method. The properties of these CI methods are explored through a simulation study. In particular, the coverage properties of the two CI methods along with their interval widths are examined for a variety of time-course patterns, error distributions, experimental protocols, and sampling designs. Fieller's method is observed to exceed nominal coverage probabilities for all conditions considered (the coverage probability being the probability that a confidence interval contains a parameter it estimates over repeated experiments). The delta method exhibited observed coverage probabilities lower than nominally specified for a number of conditions. For sampling designs in which more of the sampling times are prior to steady state or the stop exposure time, the delta method is observed to provide nominal coverage probabilities with interval widths much narrower than observed with the Fieller's method. Thus, the delta method is preferable when the above sampling time condition is met; however, in all other cases, Fieller's method should be used.
Time and space issues in ecotoxicology: Population models, landscape pattern analysis, and long-range environmental chemistry
Authors: Ares Jorge 
Published: March 2010

AbstractAdvances in ecotoxicology addressing problems of time and spatial scales are presented and interpreted in the frame of concepts on population/community dynamics and landscape pattern analysis. Example deterministic/probabilistic modeling experiments are used to illustrate key concepts. Space and time scales analyzed are single and multigenerations of local populations, metapopulations, community, and ecosystem/landscape. Most population models used in recent ecotoxicology studies are deterministic and do not include a formal treatment of spatial processes, like migration or local random extinction. Some metapopulation models have been applied with success. Upscaling of ecotoxicological results at the community level is less developed, probably because of the inherent complexity of indirect and direct coactions among organisms. Community and ecosystem toxicity end points that could find a broad use in regulatory applications have not yet been identified. Some practical issues like the estimation of the potential for the natural attenuation of toxicity and the transport of contaminants along food chains must be addressed at these scales/levels of biological complexity. The estimation of ecotoxicological effects has been increasingly evolving to integrate modeling and monitoring contaminant transport and fate, landscape pattern analysis, and spatially explicit population dynamics (including direct and indirect communal interactions).
Closing the loop: A spatial analysis to link observed environmental damage to predicted heavy metal emissions
Authors: Colgan Anja , Hankard Peter K. , Spurgeon David J. , Svendsen Claus , Wadsworth Richard A. , Weeks Jason M. 
Published: March 2010

Abstract
In many cases, the link between industrial emissions and damage to the environment can only be inferred. The Environment Agency of the United Kingdom imposes emissions limits on industrial sites so that predicted concentrations and deposition rates remain below standard thresholds. Estimates of appropriate critical levels and loads are usually based on laboratory results and rarely estimate synergistic effects between pollutants or consider biological adaptation or selection in the target receptor organisms. The Avonmouth smelter has been emitting zinc and other heavy metals since 1929. It has been the subject of a number of detailed and synoptic studies, especially the impact on soil invertebrates. Damage was assessed using both physiological and ecological measurements. Two methods of spatial analysis were investigated, namely interpolation using standard geographical information system (GIS) operators and atmospheric dispersal modeling using an off-the-shelf model. Both methods can be used to compute contours (isolines) of predicted biological effect. Correlation results show that dispersal modeling is at least as good as kriging but requires much less data. This article demonstrates the usefulness of GIS and dispersal models as tools in decision making to determine the most suitable sampling sites in the assessment and monitoring of the impact of contamination around major point sources.
Dos and don'ts of spatially explicit ecological risk assessments
Authors: Woodbury Peter B. 
Published: March 2010

Abstract
Location affects exposure and response to stressors at scales ranging from small sites to large regions. Tools such as geographic information systems (GIS) make it feasible to conduct spatially explicit ecological risk assessments (ERAs). However, no tools provide a panacea, and complex models based on sparse data can be inappropriate and misleading. Operations such as an interpolation within a GIS are models, and so they contain assumptions and uncertainties. Errors can propagate easily as numerous operations are performed, and the resulting uncertainties should be made explicit. Analysts should assure that space actually matters by using explanatory data prior to investigating spatial correlation. Exposure and risk estimates from experimental plots or monitoring stations may require scaling factors if they are to be used for larger watersheds or regional analyses. Maps are useful because they present complex spatial information in a manner that is easily interpreted. However, they must be prepared and interpreted with caution because they can suggest that there is a great deal more information than actually exists. In addition to presenting maps of predicted risks, maps of the spatial patterns in the uncertainties in these risk estimates should be included in risk assessments.
Database mining with adaptive fuzzy partition: Application to the prediction of pesticide toxicity on rats
Authors: Pintore Marco , Piclin Nadège , Benfenati Emilio , Gini Giuseppina , Chrétien Jacques R. 
Published: March 2010

Abstract
A data set of 235 pesticide compounds, divided into three classes according to their toxicity toward rats, was analyzed by a fuzzy logic procedure called adaptive fuzzy partition (AFP). This method allows the establishment of molecular descriptor/chemical activity relationships by dynamically dividing the descriptor space into a set of fuzzily partitioned subspaces. A set of 153 molecular descriptors was analyzed, including topological, physicochemical, quantum mechanical, constitutional, and electronic parameters, and the most relevant descriptors were selected with the help of a procedure combining genetic algorithm concepts and a stepwise method. The ability of this AFP model to classify the three toxicity classes was validated after dividing the data set compounds into training and test sets, including 165 and 70 molecules, respectively. The experimental class was correctly predicted for 76% of the test-set compounds. Furthermore, the most toxic class, particularly important for real applications of the toxicity models, was correctly predicted in 86% of cases. Finally, a comparison between the results obtained by AFP and those obtained by other classic classification techniques showed that AFP improved the predictive power of the proposed models.
Development of a short-term reproductive endocrine bioassay using steroid hormone and vitellogenin end points in the estuarine mummichog (Fundulus heteroclitus)
Authors: MacLatchy Deborah L. , Courtenay Simon C. , Rice Charles D. , Van Der Kraak Glen J. 
Published: March 2010

AbstractWe have developed a short-term gonadal recrudescence test with the estuarine mummichog (Fundulus heteroclitus) and determined endocrine end points sensitive to a strong estrogen agonist (ethynylestradiol; EE2) and an antiestrogen (ZM 189,154; ZM) at concentrations of 0 to 1,000 ng/L in three separate experiments. A protocol was developed to ensure a year-round supply of recrudescing fish. A protocol for determining steroid production (testosterone and 11-ketotestosterone [11-KT] in incubated testes tissue and testosterone and 17-estradiol [E2] in incubated prematurational follicles) was optimized. Recrudescing fish (males, gonadosomatic index = 2%; females = 10%) were exposed to graded doses of EE2 or ZM for 7 to 15 d using a static daily-renewal protocol. At high EE2 (&gt;250 ng/L), the effect on males was depression of androgen steroidogenesis and plasma steroid levels. In females, high EE2 depressed gonadal production and circulating E2 levels; however, EE2 concentrations &lt;100 ng/L caused increased gonadal production and plasma E2. Low ZM (&lt;100 ng/L) had little effect on male and female fish, while higher concentrations (&gt;250 ng/L) increased E2 and 11-KT production while decreasing plasma 11-KT and E2 (1,000 ng/L only). Male and female plasma vitellogenin responded in a concentration-dependent fashion to EE2 with no effect by ZM. The low observable effect concentrations for the endocrine parameters were 1 ng/L for EE2 and 250 ng/L for ZM. The bioassay and results encompassing the environmentally relevant exposure range (1–100 ng/L) will be useful for assessing effects of endocrine-active contaminants in estuarine environments.
Kinetics of benzene biodegradation by Pseudomonas aeruginosa: Parameter estimation
Authors: Kim Song-Bae , Park Choon-Hwa , Kim Dong-Ju , Jury William A. 
Published: March 2010

Abstract
This study determined the model parameters describing biodegradation of benzene by conducting kinetic microcosm batch tests in both pure solution and saturated aquifer material conditions for various initial benzene (100–700 mg/L) and microbial concentrations (107–109 colony-forming units [CFU]/ml) using Pseudomonas aeruginosa as benzene-degrading bacteria. In both tests, benzene and microbial concentrations were monitored over time in order to investigate which of two Monod kinetic equations, the Monod-with-growth or the Monod-no-growth model, was more suitable for describing benzene biodegradation and to estimate the associated model parameters. Parameter estimation was performed by fitting the numerical solution of each model obtained by the fourth-order Runge-Kutta integration to the measured data of benzene and/or microbial concentrations. For the Monod-with-growth model, the best fit of the numerical solution was significantly different than the measured benzene concentrations, especially at early times, because of the gradual increase of microbial population in the growth curve. In contrast, the solution based on the Monod-no-growth model produced reasonable agreement with the measured benzene data. The estimated parameters of maximum substrate utilization rate (kmax) and half-saturation constant (Kc) were in the range of 61 to 105 mg/L/d and about 270 mg/L, respectively, which differ significantly from values previously reported in the literature. We attribute the differences observed in our study to our experimental conditions of initial substrate and bacterial concentrations and oxygen and nutrient supply. Our results imply that an appropriate model type and reasonable values of kinetic parameters should be chosen to model the biodegradation of hydrocarbons in the subsurface environment.