bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms affecting the dissolution of nonaqueous phase liquids into the aqueous phase in slow-stirring batch systems
Authors: Schluep Mathias , Imboden Dieter M , Gälli René , Zeyer Josef 
Published: March 2010

AbstractUnderstanding the kinetics of the exchange processes between nonaqueous phase liquids (NALs) and water is important in predicting the fate of anthropogenic compounds such as petroleum hydrocarbons, i.e., benzene, toluene, ethylbenzene, and xylene (BTEX) as well as polynuclear aromatic hydrocarbons (PAHs). Exchange processes occurring in the environment resemble the experimental setup of the slow-stirring method (SSM) designed to determine solubilities and octanol-water partition coefficients. Data obtained from SSM experiments for diesel fuel compounds are interpreted by a linear transfer model that is characterized by an aqueous molecular boundary layer and the water/NAPL equilibrium partition coefficient. For the chosen experimental setup, the boundary layer thickness is 2.42 × 10−2 cm. Typical equilibration times lie between 1 and 2 d. Due to the temperature dependence of the aqueous diffusivity, this time increases with decreasing temperature. Transport within the NAPL phase can slow down the exchange process for the more water-soluble compounds (e.g., benzene) provided that the stirring rate exceeds a critical value.
Sperm cell toxicity test using sea UrchinParacentrotus lividuslamarck (Echinodermata: Echinoidea): Sensitivity and discriminatory ability toward anionic and nonionic surfactants
Authors: Ghirardini Annamaria Volpi , Novelli Alessandra Arizzi , Likar Barbara , Pojana Giulio , Ghetti Pier Francesco , Marcomini Antonio 
Published: March 2010

AbstractA reliable sperm cell toxicity test procedure has been developed for the Mediterranean sea urchin Paracentrotus lividus. The sensitivity and discriminatory ability of the test were investigated with regard to surfactants and their biotransformation products. Aromatic and aliphatic surfactants of anionic (linear alkylbenzene sulfonates [LAS]) and nonionic (alcohol polyethoxylates [AE] and nonylphenol polyethoxylates [NPE]) types and their aerobic biodegradation products, i.e., sulfophenylcarboxylates (SPC), polyethylene glycols (PEG), carboxylated polyethylene glycols (PEGC), carboxylated AE (AEC), and nonylphenol (NP), were examined in order to elucidate the influence of their molecular structure on toxicity. Experimental results reveal that the sperm cell test showed good discriminatory ability among all tested compounds, median effective concentration (EC50) values differing by about four orders of magnitude. The toxicity of anionic surfactants depends on the length of the alkyl chain and that of nonionic surfactants is due to their length and branching. Much lower toxicity was shown by aerobic biodegradation products in comparison with that of their parent compounds, with the exception of NP. The obtained EC50s were comparable with available literature data and constitute new toxicity data regarding surfactants for sea urchins.
An evaluation of the etiology of reduced CYP1A1 messenger RNA expression in the Atlantic tomcod from the Hudson River, New York, USA, using reverse transcriptase polymerase chain reaction analysis
Authors: Roy Nirmal K , Courtenay Simon , Yuan Zhanpeng , Ikonomou Michael , Wirgin Isaac 
Published: March 2010

AbstractAdult Atlantic tomcod, Microgadus tomcod, from the Hudson River, New York State, USA, exhibit reduced inducibility of hepatic cytochrome P4501A1 (CYP1A1) mRNA compared with adult tomcod from the cleaner Miramichi River, New Brunswick, Canada, when treated with coplanar polychlorinated biphenyl (PCB) congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin. In contrast, little difference in CYP1A1 inducibility is observed between tomcod from these two rivers when treated with polycyclic aromatic hydrocarbons (PAHs). We sought to determine if impaired hepatic CYP1A1 inducibility in Hudson River tomcod results from a multigenerational, genetic adaptation or a single generational, physiological acclimation. Embryos and larvae from controlled experimental crosses of Hudson River and Miramichi River parents were exposed for 24 h to water-borne PCB congener 77 (10 ppm), benzo[a]pyrene (BaP; 10 ppm), or dimethysulfoxide, and CYP1A1 expression was assessed in individual larva using competitive reverse transcriptase polymerase chain reaction (RT-PCR) analysis. The CYP1A1 mRNA was significantly induced in larvae from both populations by BaP (47- and 52-fold) and PCB 77 (9- and 22-fold), although levels of expression were higher in offspring of Miramichi matings. Most important, CYP1A1 mRNA was significantly induced by PCB 77 in larvae from Hudson River parents. Concentrations of dioxin, furan, and PCB congeners were measured in livers and eggs of female tomcod from these two locales to quantify the extent of maternal transfer of contaminants. For both rivers, wet-weight contaminant concentrations were significantly higher (4–7 times) in livers than in eggs of the same females, suggesting that a threshold level of contaminants may have to be reached before CYP1A1 transcription is impaired. We conclude that reduced inducibility of hepatic CYP1A1 mRNA in adult tomcod from the Hudson River is most consistent with single-generational acclimation.
Effects of salinity and chemical speciation on cadmium accumulation and toxicity to two mysid species
Authors: Roast Stephen D , Widdows John , Jones Malcolm B 
Published: March 2010

AbstractThe estuarine environment is characterized by frequent fluctuations in salinity. Consequently, organisms used for environmental monitoring of estuaries must be euryhaline so that their laboratory responses to chemical pollutants are measured under the full range of salinity exposures experienced in the field. Neomysis integer and Praunus flexuosus are two potential candidates for use in environmental monitoring of European estuaries. The present study assesses the effects of salinity on survival, trace metal accumulation, and toxicity to these two mysid species. Neomysis integer was more euryhaline, showing 100% survival at 1 to 40‰ compared with P. flexuosus, which showed 100% survival at salinities of 10 to 40‰. Toxicity of the free cadmium ion to both species was unaffected by salinity, and 96-h LC50s ranged from 4.8 to 15 μg Cd2+/L for N. integer and from 12.3 to 16 μg Cd2+/L for P. flexuosus. The 7-d LC50s ranged from 1.0 to 4.2 and 4.8 to 5.3 μg Cd2+/L for N. integer and P. flexuosus, respectively. No effect of exposure salinity was found on cadmium body burdens of mysids exposed for 7 d to 0.5 and 1.0 μg Cd2+/L. The results are discussed in terms of possible effects of osmoregulatory mechanisms on trace metal uptake, accumulation, and toxicity.
Determination and multivariate statistical analysis of biochemical responses to environmental contaminants in feral freshwater fishLeuciscus cephalusL.
Authors: Machala Miroslav , Dusek Ladislav , Hilscherova Klara , Kubinova Renata , Jurajda Pavel , Neca Jiri , Ulrich Robert , Gelnar Milan , Studnickova Zdena , Holoubek Ivan 
Published: March 2010

AbstractModulations of 11 prospective biochemical markers of impacts of aquatic pollutants in liver tissue of chub (Leuciscus cephalus), caught at several sampling sites of a river with various pollution types and rates, were matched against analytical data of concentrations of organochlorine compounds, polycyclic aromatic hydrocarbons (PAHs), and heavy metals. Multivariate principal component analysis (PCA) of the field data showed general patterns of biochemical responses to different types of pollutants and relationships among the biomarkers. Cytochrome P4501A-dependent 7-ethoxyresorufin O-deethylase (EROD) activity, inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin and structurally related planar compounds, was strongly enhanced in the more contaminated areas. Compared with polychlorinated aromatic hydrocarbons, PAHs did not contribute so significantly to EROD induction. Testosterone 6β- and 16α-hydroxylase activities, as an expression of the cytochrome P4503A27, were slightly increased at several sites but were significantly decreased in samples from some heavily polluted areas. Recently, these activities have been suggested as potential biomarkers of exposure to contaminants that do not induce cytochrome P4501A. In this study, their inhibition or induction was not associated with a specific class of monitored contaminants, and selectivities of these modulations are still to be investigated. Similar modulations of the prospective biochemical indicators of oxidative stress, including microsomal glutathione S-transferase activity, cytosolic glutathione S-transferase with ethacrynic acid, and glutathione reductase, were demonstrated by PCA. The pattern of the modulations of the microsomal nicotinamide adenine dinucleotide phosphate (NADPH)-dependent lipid peroxidation in vitro differed from the responses of the rest of oxidative stress parameters at some sampling sites. Further biochemical markers of oxidative stress under study, including in vivo lipid peroxidation, in vitro production of reactive oxygen species, and the concentration of metallothioneins did not correlate well with the concentrations of the contaminants. Principal component analysis demonstrated that the EROD activity, glutathione-dependent enzymes, and Fe(II)-enhanced lipid peroxidation formed a suitable battery of biomarkers of exposure.
Stable strontium accumulation by earthworms: A paradigm for radiostrontium interactions with its cationic analogue, calcium
Authors: Morgan John E , Richards Sarah P G , Morgan A John 
Published: March 2010

AbstractThe accumulation of stable strontium and its chemical analogue calcium by four species of earthworm, representing three distinct ecophysiological groups inhabiting celestite (SrSO4)-rich natural soils, was investigated. An increase in soil strontium concentration over a four-orders-of-magnitude range was accompanied by an increase in earthworm tissue strontium concentration. In contrast, no relationship between soil and tissue calcium concentrations was apparent, indicating that this essential cation is strongly regulated within earthworm tissues but that nonessential strontium burdens are not physiologically regulated. Concentration factors for strontium ranged from 0.1 to 1.42, with an inverse relationship between this parameter and soil strontium concentration. The use of concentration factors and discrimination coefficients lead to the conclusion that earthworms discriminate against strontium accumulation at increased soil calcium concentrations, such that strontium would be predicted to be more efficiently accumulated by worms inhabiting acidic, calcium-poor soils. Although few consistent trends in strontium and calcium concentration were apparent between earthworm species, the species with the highest calcium turnover (i.e., the litter-inhabiting Lumbricus rubellus) typically accumulated higher concentrations of strontium than representatives of contrasting ecophysiological classes. These findings are considered in the context of the distribution, retention, and cycling of radiostrontium in soils.
Fate and effects of esfenvalerate in agricultural ponds
Authors: Samsøe-Petersen Lise , Gustavson Kim , Madsen Torben , Mogensen Betty Bügel , Lassen Pia , Skjernov Kamilla , Christoffersen Kirsten , Jørgensen Erik 
Published: March 2010

AbstractThe fate of esfenvalerate was investigated by sampling and chemical analysis after spraying of an artificial pond (25 g a.i./ha) and in the laboratory with [14C]esfenvalerate by trapping of 14CO2 and fractionation of the sediment. The effects were investigated on pelagic communities in enclosures in a natural lake and in the laboratory on surface (Cymatia coleoptrata) and sediment (Chironomus riparius) insects. The latter were used in sediment-plus-water and in water-only tests, measuring effects on emergence and mortality. The measurements in the artificial pond indicated exposure concentrations in the surface microlayer, water column, and sediment of 0.4 μg/L, 0.05 μg/L, and 9 μg/kg dry weight, respectively, two weeks after application. The degradation studies showed a limited mineralization (26.5%) of [chlorophenyl-14C]esfenvalerate during 112 d. Part of the substance was transformed to water-soluble compounds (18.1%) or compounds attached to fulvic acids (26.2%), humic acids (14.2%), or nonextractable sediment constituents (8.8%). The formulated product Sumi-Alpha 5 FW® caused 100% mortality to Cymatia coleoptrata after surface application of 0.13 g a.i./ha. Effects on zooplankton were recorded at 0.005 μg/L of esfenvalerate. The 96-h median lethal concentration for first-instar larvae of Chironomus riparius was 0.13 μg/L, whereas the delayed emergence lowest-observed-effect concentration was 0.8 μg/L.
Utility of a juvenile fathead minnow screening assay for detecting (anti-)estrogenic substances
Authors: Panter Grace H. , Hutchinson Thomas H. , Länge Reinhard , Lye Christina M. , Sumpter John P. , Zerulla Melanie , Tyler Charles R. 
Published: March 2010

AbstractThe European Chemical Industry's aquatic research program for endocrine disrupters includes the development of an in vivo juvenile fathead minnow (Pimephales promelas) screening assay.Working within the Organization for Economic Cooperation and Development's (OECD, Paris, France) tiered approach to endocrine disrupter evaluation in fish, the juvenile fish screening protocol was adapted from the OECD test guideline 204. Six chemicals, with different (anti-)estrogenic potencies, were used to develop the in vivo juvenile fish screening protocol: diethylstilbestrol, 17α-ethynylestradiol, genistein, methoxychlor, 4-tert-pentylphenol, and ZM189,154 (a novel pharmaceutical antiestrogen). Mixed-sex juvenile fathead minnows were exposed to individual chemicals (with chemical analyzes) and sampled after 4, 7, 14, and 21 d of exposure. Wet weight, total length, condition factor, and whole-body homogenate concentrations of vitellogenin (VTG) were determined. Estrogens and antiestrogens were detected in this screen by virtue of the VTG response (an elevation or suppression, respectively) after 14 d. The study showed that the use of VTG concentrations in mixed-sex juvenile fish provides a sensitive and robust assay for the detection of both estrogenic and antiestrogenic chemicals, with widely divergent potencies.
Population responses of the freshwater amphipodGammarus pulex(L.) to an environmental estrogen, 17α-ethinylestradiol
Authors: Watts Matthew M. , Pascoe David , Carroll Kathleen 
Published: March 2010

AbstractThe effects of the environmental estrogen 17α-ethinylestradiol (EE) on mixed populations of 90 individual Gammarus pulex were examined following a 100-d exposure in a flow-through system. Counts of total animal numbers revealed that, in all treatment groups, population size dramatically increased due to recruitment, with neonate and juvenile gammarids the most abundant. At concentrations of 1 and 10 μg/L EE, the recorded mean population sizes of 385 and 411, respectively, were significantly greater (p = 0.018) than the control (169). Mean population sizes in the solvent control (257) and 100 ng/L EE treatment (267) were not significantly different (p &gt; 0.05) from the control. In addition to total counts, detailed image analysis of each individual animal allowed the assessment of length—frequency distributions, adult sex ratio, number of precopula pairs/ovigerous females, and measurement of secondary antenna and gnathopod length (secondary sex characteristics). The sex ratio of adults at 100 ng, 1 μg, and 10 μg/L EE was greater than 2:1 (female:male), and significantly more females (p = 0.008) were recorded at these concentrations compared with the control. The number of male adults, precopula guarding pairs, and ovigerous females did not differ between treatments (p &gt; 0.05). Secondary antennal and gnathopod length in males was consistently greater than in females (p ≤ 0.001), but comparison between groups revealed no difference in these parameters.
Polychlorinated dibenzo-p-dioxins and dibenzofurans and dioxinlike polychlorinated biphenyls in sediments and mussels at three sites in the lower Great Lakes, North America
Authors: Marvin Christopher H. , Howell E. Todd , Kolic Terry M. , Reiner Eric J. 
Published: March 2010

AbstractLevels of contaminants including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non-ortho-substituted and mono-ortho-substituted dioxinlike polychlorinated biphenyls (DLPCBs) were determined in sediments and freshwater mussels (Dreissena spp. and Elliptio complanata) at three sites in the lower Great Lakes (North America). Impacts of mussel colonization on sediment quality were investigated by comparing contaminant levels in colonized sediment with levels in sediment in the same area that was not colonized, but exposed to similar environmental conditions. Significant impacts on contaminant levels of colonized sediment, compared to noncolonized sediment, were observed at two sites exhibiting high mussel population densities (Fort Erie, eastern Lake Erie, ON, Canada, 2.2 kg/m2 dry wt biomass, and Port Dalhousie, western Lake Ontario, Ontario, Canada, 6.1 kg/m2 dry wt biomass); these differences were not observed at a site with lower mussel densities (Bay of Quinte, eastern Lake Ontario, Ontario, Canada, 0.7 kg/m2). Total organic carbon and contaminant concentrations were statistically significantly greater in colonized sediment, compared to noncolonized sediment, at the two impacted sites. Areal estimates of PCDD/PCDF and DLPCB toxicity equivalents (TEQs) in mussel biomass at the three sites averaged 0.16% and 3.3%, respectively, of the TEQs in the top 3 cm of sediment, indicating that the sediments were the primary sink for contaminants. The observed differences between colonized and noncolonized sediment suggest that Dreissena are capable of influencing the chemical properties of sediment they colonize.
Predicting amphipod toxicity from sediment chemistry using logistic regression models
Authors: Field L. Jay , MacDonald Donald D. , Norton Susan B. , Ingersoll Christopher G. , Severn Corinne G. , Smorong Dawn , Lindskoog Rebekka 
Published: March 2010

AbstractIndividual chemical logistic regression models were developed for 37 chemicals of potential concern in contaminated sediments to predict the probability of toxicity, based on the standard 10-d survival test for the marine amphipods Ampelisca abdita and Rhepoxynius abronius. These models were derived from a large database of matching sediment chemistry and toxicity data, which includes contaminant gradients from a variety of habitats in coastal North America. Chemical concentrations corresponding to a 20, 50, and 80% probability of observing sediment toxicity (T20, T50, and T80 values) were calculated to illustrate the potential for deriving application-specific sediment effect concentrations and to provide probability ranges for evaluating the reliability of the models. The individual chemical regression models were combined into a single model, using either the maximum (PMax model) or average (PAvg model) probability predicted from the chemicals analyzed in a sample, to estimate the probability of toxicity for a sample. The average predicted probability of toxicity (from the PMax model) within probability quartiles closely matched the incidence of toxicity within the same ranges, demonstrating the overall reliability of the PMax model for the database that was used to derive the model. The magnitude of the toxic effect (decreased survival) in the amphipod test increased as the predicted probability of toxicity increased. Users have a number of options for applying the logistic models, including estimating the probability of observing acute toxicity to estuarine and marine amphipods in 10-d toxicity tests at any given chemical concentration or estimating the chemical concentrations that correspond to specific probabilities of observing sediment toxicity.
Lizard cholinesterases as biomarkers of pesticide exposure: Enzymological characterization
Authors: Sanchez-Hernandez Juan C. , Sanchez Beatriz Moreno 
Published: March 2010

AbstractHere we report the results of a study conducted to elucidate the enzymological characteristics of lizard cholinesterases (ChEs) in order to use them as potential biomarkers for pesticide exposure. Serum and brain tissue of the lizard Gallotia galloti were used as ChE sources and in vitro assays were performed to identify acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities. The pH, substrate concentration, and specificity for ChE assays as well as the response of serum BChE to the reactivating agent pyridine-2-aldoxime methochloride (2-PAM) were also investigated in order to assess the possibilities of this methodology in biomonitoring programs. By the use of selective substrates and the inhibitor tetraisopropyl pyrophosphoramide, AChE and BChE activities were identified in lizard serum, while brain contained solely AChE. Likewise, butyrylthiocholine iodide was the optimum substrate for determining BChE activity and acetylthiocholine iodide for assaying both serum and brain AChE activities. The optimal ranges of pH and substrate concentrations were 7.5 to 8.0 and 5 to 10 mM, respectively. Serum was incubated with different doses of the organophosphorus (OP) compounds dichlorvos and paraoxon and subsequently incubated in the presence of two concentrations of 2-PAM (2 × 10−2 or 2 × 10−4 M). Reactivation rate of phosphorylated BChE was related to the degree of inhibition of BChE and the dose of 2-PAM. It was found that a 90-min incubation time with 2 × 10−4 M of 2-PAM satisfactorily increased the OP-inhibited BChE activity. The enzymological properties of serum BChE activity and its in vitro reactivation in the presence of 2-PAM represent the initial justification for its use in monitoring OP contamination in the field.
Role of metalloporphyrin core metals in the mediated reductive dechlorination of tetrachloroethylene
Authors: Dror Ishai , Schlautman Mark A. 
Published: March 2010

AbstractA promising approach to abiotically dechlorinate a variety of chlorinated organic contaminants under reducing conditions is to utilize porphyrins or other tetrapyrrole macrocycles as electron transfer mediators/shuttles for catalyzing their reduction. In this study, various experimental approaches were used to elucidate the role of porphyrin core metals in the reductive dechlorination of tetrachloroethylene (PCE). The importance of specific core metals for the reactivity of a porphyrin and its mediated reaction mechanisms was demonstrated by inserting different metals into metallo tetrakis (N-methyl-4-4 pyridiniumyl) porphyrin (TMPyP). No PCE dechlorination was observed when the free-base (i.e., no core metal) and iron core metal forms of TMPyP were utilized. When using nickel or cobalt TMPyP, reductive dechlorination of PCE occurred but appeared to follow different pathways for the two metals based on product analyses. Physical (e.g., steric) considerations suggest that direct contact between a porphyrin core metal and PCE may be limited and therefore that the entire metalloporphyrin molecule should be viewed as a functional system in which the organic macrocycle has an active part in reductive dechlorination reactions. This view is supported by the fact that slight changes in the functional groups on a porphyrin macrocycle, particularly those far removed from the core metal itself, greatly affected the reactivity and mechanism of the porphyrin. Solution conditions also had a major effect on porphyrin reactivities, to the extent that a nonreactive metalloporphyrin could be activated merely by adjusting the pH of the solution or by adding a small amount of cosolvent. The collective results of this study suggest that fine tuning of naturally occurring metalloporphyrin complexes and/or their environments can enhance the catalyzed detoxification of chlorinated contaminants in many natural and engineered environmental systems.