bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of repeated exposure to 4-nonylphenol on the zooplankton community in littoral enclosures
Authors: O'halloran Susan L , Liber Karsten , Gangl James A , Knuth Michael L
Published: March 2010

The effects of 4-nonylphenol (NP) on freshwater zooplankton were evaluated in 18 littoral enclosure mesocosms in northeastern Minnesota. The 18 enclosures were allocated to three blocks of six units with each block including two untreated control enclosures and one enclosure for each of four NP treatments (3, 30, 100, and 300 μg/L). Treated enclosures received 11 applications of NP over a 20-d period between July 8 and 28, 1993. Maximum NP concentrations measured in the water column 2 h after each application averaged (±SD) 5 ± 4, 23 ± 11, 76 ± 21, and 243 ± 41 μg/L over the 11 applications. Nonylphenol dissipated rapidly from the water column but was more persistent in sediments and in/on macrophytes. All cladoceran and copepod taxa were significantly reduced in abundance at 243 ± 41 μg/L; some sensitive taxa were also affected at 76 ± 21 and 23 ± 11 μg/L. While many rotifer taxa were unaffected at any of the test concentrations, several were affected at ≥76 ± 21 μg/L. Ostracods were only affected at 243 ± 41 μg/L. No zooplankton taxon was affected at 5 ± 4 μg/L. The period of maximum impact usually occurred within 1 to 7 d of the last NP application, and recovery to control abundance levels generally occurred within 7 to 28 d of the last NP application. Two sensitive taxa, Acroperus and Calanoida, did not recover at ≥76 ± 21 μg/L by the end of the study. The maximum acceptable toxicant concentration for protection of all zooplankton taxa was estimated at ˜10 μg/L, although overall community diversity was unaffected at 23 ± 11. The water was the most probable route of NP exposure, but the greater persistence of NP residues in/on macropyhtes may have contributed to the lack of recovery of some macrophyte-associated taxa.
Effects of 4-nonylphenol on benthic macroinvertebrates and insect emergence in littoral enclosures
Authors: Schmude Kurt L , Liber Karsten , Corry Timothy D , Stay Frank S
Published: March 2010

The effect of 4-nonylphenol (NP) on benthic, freshwater macroinvertebrates in littoral enclosures was evaluated over a 2-year period. Enclosures received 11 NP applications, 48 h apart, with nominal rates of 3, 30, 100, and 300 μg/L. Mean measured peak concentrations in integrated water column samples over the 20-d application period were 5 ± 4, 23 ± 11, 76 ± 21, and 243 ± 41 μg/L NP. Concentrations of NP in the water column decreased rapidly after the last application. Maximum NP concentrations measured in sediments, pore water, and macrophytes of a 300-μg/L enclosure were 27.4 mg/kg, 29.9 μg/L, and 89.6 mg/kg, respectively. The most abundant macroinvertebrate groups, Chironomidae, Oligochaeta, and Mollusca, decreased in abundance after application. Effects on Mollusca were the most severe. Their numbers were significantly reduced at the highest treatment (243 ± 41 μg/L NP) throughout most of the study. Oligochaetes (Naididae, Tubificidae) and chironomids (Tanytarsini, Chironomini) were also significantly reduced at the highest treatment, but populations recovered within 6 weeks. Snails and naidid oligochaetes were slightly affected at the second highest treatment (76 ± 21 μg/L NP). Insect emergence was reduced during and immediately postapplication, but the effects were likely caused or compounded by a surfactant sheen on the surface of the water that interfered with emergence and/or oviposition. The observed effects on the benthic community were most likely due to exposure from the water, although more persistent macrophyte-associated residues may have contributed to effects on Gastropoda, Naididae, and Tanytarsini. Macrophyte-associated NP residues may pose a small risk to benthic organisms, but it is probably minor compared to water exposures. The no-observed and lowest-observed-effect concentration for the benthic community was 23 ± 11 and 76 ± 21 mg/L NP, respectively.
Organochlorine contaminants and reproductive success of double-crested cormorants from Green Bay, Wisconsin, USA
Authors: Custer Thomas W , Custer Christine M , Hines Randy K , Gutreuter Steve , Stromborg Kenneth L , Allen P David , Melancon Mark J
Published: March 2010

In 1994 and 1995, nesting success of double-crested cormorants (Phalacrocorax auritus) was measured at Cat Island, in southern Green Bay, Lake Michigan, Wisconsin, USA. Sample eggs at pipping and unhatched eggs were collected and analyzed for organochlorines (including total polychlorinated biphenyls [PCBs] and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in embryos, and eggshell thickness. Of 1,570 eggs laid, 32% did not hatch and 0.4% had deformed embryos. Of 632 chicks monitored from hatching to 12 d of age, 9% were missing or found dead; no deformities were observed. The PCB concentrations in sample eggs from clutches with deformed embryos (mean = 10.2 μg/g wet weight) and dead embryos (11.4 μg/g) were not significantly higher than concentrations in sample eggs from nests where all eggs hatched (12.1 μg/g). A logistic regression of hatching success versus DDE, dieldrin, and PCB concentrations in sibling eggs identified DDE and not dieldrin or PCBs as a significant risk factor. A logistic regression of hatching success versus DDE and eggshell thickness implicated DDE and not eggshell thickness as a significant risk factor. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in double-crested cormorant eggs in Green Bay are still having an effect on reproduction in this species.
Avoidance response of the estuarine amphipodEohaustorius estuariusto polycyclic aromatic hydrocarbon-contaminated, field-collected sediments
Authors: Kravitz Michael J , Lamberson Janet O , Ferraro Steven P , Swartz Richard C , Boese Bruce L , Specht David T
Published: March 2010

Amphipods (Eohaustorius estuarius) were placed in two-chamber containers with different combinations of three contaminated sediments and a control sediment, and their distribution was determined after 2 or 3 d. Amphipods avoided the sediment with the highest PAH contamination and one of two sediments with moderate PAH concentrations. In the moderately contaminated sediment avoided by amphipods, the (avoidance) response was more sensitive than mortality as a biological indicator of unacceptable sediment contamination (over the 2–3-d exposure). The avoidance response in this case likely represents an early indication of potential mortality from sediment exposure. Population levels of amphipods in moderately to heavily PAH-contaminated sediments may be influenced by a combination of avoidance behavior and toxicity/lethality.
Fish mercury distribution in Massachusetts, USA lakes
Authors: Rose Jane , Hutcheson Michael S , West Carol Rowan , Pancorbo Oscar , Hulme Kenneth , Cooperman Al , Decesare Gregory , Isaac Russell , Screpetis Arthur
Published: March 2010

The sediment, water, and three species of fish from 24 of Massachusetts' (relatively) least-impacted water bodies were sampled to determine the patterns of variation in edible tissue mercury concentrations and the relationships of these patterns to characteristics of the water, sediment, and water bodies (lake, wetland, and watershed areas). Sampling was apportioned among three different ecological subregions and among lakes of differing trophic status. We sought to partition the variance to discover if these broadly defined concepts are suitable predictors of mercury levels in fish. Average muscle mercury concentrations were 0.15 mg/kg wet weight in the bottom-feeding brown bullheads (Ameiurus nebulosus) (range = 0.01–0.79 mg/kg); 0.31 mg/kg in the omnivorous yellow perch (Perca flavescens) (range = 0.01–0.75 mg/kg); and 0.39 mg/kg in the predaceous largemouth bass (Micropterus salmoides) (range = 0.05–1.1 mg/kg). Statistically significant differences in fish mercury concentrations between ecological subregions in Massachusetts, USA, existed only in yellow perch. The productivity level of the lakes (as deduced from Carlson's Trophic Status Index) was not a strong predictor of tissue mercury concentrations in any species. pH was a highly (inversely) correlated environmental variable with yellow perch and brown bullhead tissue mercury. Largemouth bass tissue mercury concentrations were most highly correlated with the weight of the fish (+), lake size (+), and source area sizes (+). Properties of individual lakes appear more important for determining fish tissue mercury concentrations than do small-scale ecoregional differences. Species that show major mercury variation with size or trophic level may not be good choices for use in evaluating the importance of environmental variables.
Influence of sediment-organic matter quality on growth and polychlorobiphenyl bioavailability in Echinodermata (Amphiura filiformis)
Authors: Gunnarsson Jonas S , Granberg Maria E , Nilsson Hans C , Rosenberg Rutger , Hellman Birthe
Published: March 2010

Sediment total organic carbon (TOC) content is considered to be a primary food source for benthic invertebrates and a major factor influencing the partitioning and bioavailability of sediment-associated organic contaminants. Most studies report that both toxicity and uptake of sediment-associated contaminants by benthic organisms are inversely proportional to sediment TOC content. The aim of this study was to determine the importance of the TOC quality for the bioavailability of sediment-associated organic contaminants and the growth of benthic macrofauna. The common infaunal brittle star Amphiura filiformis was exposed to a base sediment covered by a 14C-polychlorobiphenyl(3,3′4,4′-14C-tetrachloiphenyl (TCB)) contaminated top layer (0−2 cm), enriched to the same TOC content with 31 g TOC/m2 of different quality and origin. The following carbon sources, ranging from labile to refractory, were used: (1) green macroalga (Ulva lactuca), (2) brown macroalga (Ascophyllum nodosum), (3) eelgrass (Zostera marina), (4) phytoplankton (Ceratium spp.), and (5) lignins of terrestrial origin. Characterization of the organic matter quality was accomplished by measuring the content of amino acids, lipids, C, N, and polyphenolic compounds. The reactivity of the sedimentary organic matter was assessed by means of respiration and dissolved inorganic nitrogen flux measurements. The experiment was carried out in 1-L glass jars, each containing four brittle stars and the contaminated and enriched sediment. The jars were circulated in a flow-through mode with filtered seawater. Somatic growth (regeneration of a precut arm) and bioaccumulation of 14C-TCB were measured at 10 sampling occasions during 48 d of exposure. Growth rates, TCB uptake rates, and steady-state concentrations differed significantly between treatments and were correlated to the qualities of the organic substrates. The greatest TCB accumulation and growth were observed in treatments with the most labile organic substrates and the lowest accumulation and growth were seen with the most refractory substrates. Results from this experiment suggest that the bioaccumulation of organic contaminants in benthic infauna is dependent on the nutritional quality of the sedimentary organic matter.
Mechanisms for adsorption of organic bases on hydrated smectite surfaces
Authors: Laird David A , Fleming Pierce D
Published: March 2010

Mechanisms by which organic bases are adsorbed on hydrated smectite surfaces were investigated. Three Ca-saturated reference smectites (Otay, SPV, and Panther Creek) were dispersed in distilled water containing 5 μmol of pyridine or 3-butylpyridine. The pH was adjusted to between 7.5 and 3 using 0.01 M HCl. After a 2-h equilibration, the amount of pyridine or 3-butylpyridine adsorbed on the clay and the amount of Ca desorbed from the clay were determined. Negligible amounts of pyridine were adsorbed by the Ca-smectites in the neutral systems (pH > 7); however, most of the added pyridine was adsorbed on the smectites in the acidified systems (pH < 5). Equivalent amounts of Ca2+ were desorbed from the clays, indicating that pyridine was adsorbed as a protonated species by cation exchange. By contrast, 40 to 90% of added 3-butylpyridine was adsorbed on the smectites at neutral pHs, whereas only small amounts of Ca2+ were desorbed. The results suggest that 3-butylpyridine is initially retained by hydrophobic bonding between the alkyl side chain of the molecule and hydrophobic nanosites located between the charge sites on smectite surfaces. Surface acidity catalyzed protonation 1 to 1.5 pH units above the pKa of the bases.
Prediction of biodegradability from chemical structure: Modeling of ready biodegradation test data
Authors: Loonen Hélène , Lindgren Fredrik , Hansen Bjørn , Karcher Walter , Niemelä Jay , Hiromatsu Koichi , Takatsuki Mineo , Peijnenburg Willie , Rorije Emiel , Struijś Jaap
Published: March 2010

Biodegradation data were collected and evaluated for 894 substances with widely varying chemical structures. All data were determined according to the Japanese Ministry of International Trade and Industry (MITI) I test protocol. The MITI I test is a screening test for ready biodegradability and has been described by Organization for Economic Cooperation and Development (OECD) test guideline 301 C and European Union (EU) test guideline C4F. The chemicals were characterized by a set of 127 predefined structural fragments. This data set was used to develop a model for the prediction of the biodegradability of chemicals under standardized OECD and EU ready biodegradation test conditions. Partial least squares (PLS) discriminant analysis was used for the model development. The model was evaluated by means of internal cross-validation and repeated external validation. The importance of various structural fragments and fragment interactions was investigated. The most important fragments include the presence of a long alkyl chain; hydroxy, ester, and acid groups (enhancing biodegradation); and the presence of one or more aromatic rings and halogen substituents (retarding biodegradation). More than 85% of the model predictions were correct for using the complete data set. The not readily biodegradable predictions were slightly better than the readily biodegradable predictions (86 vs 84%). The average percentage of correct predictions from four external validation studies was 83%. Model optimization by including fragment interactions improved the model predicting capabilities to 89%. It can be concluded that the PLS model provides predictions of high reliability for a diverse range of chemical structures. The predictions conform to the concept of readily biodegradable (or not readily biodegradable) as defined by OECD and EU test guidelines.
Degradation of linear alkylbenzene sulfonate in soil columns
Authors: Branner Ulla , Mygind Merete , Jørgensen Claus
Published: March 2010

This study investigated the ability of a microbial community to degrade linear alkylbenzene sulfonate (LAS) in soil columns under water-saturated conditions. The microbial mineralization of LAS was further studied in a batch experiment using pre-exposed and unexposed soil as well as soil from the inlet and outlet of the columns. The LAS (4 mg/L) was added continuously to the columns. Three pulses of 14C-labeled LAS (14C-dodecyl-[6]-benzene sulfonate) were added at intervals of 2 weeks, and the mineralization was measured as production of 14CO2. The primary degradation of LAS was close to 100% in the columns, whereas the mineralization of the 14C-labeled compound reached only 9%. The degradation products of LAS proved to be significantly less sorbtive than LAS itself. In the batch experiment, mineralization of LAS occurred in unexposed soil after a short lag phase. The mineralization proved to be more dependent on a high representation of biomass than on previous exposure to LAS.
Effects of exposure to azaarenes on emergence and mouthpart development in the midgeChironomus riparius(Diptera: Chironomidae)
Authors: Bleeker Eric A.J , Leslie Heather A , Groenendijk Dick , Plans Marc , Admiraal Wim
Published: March 2010

Adverse effects of azaarenes on emergence and mouthpart development of the midge Chironomus riparius were analyzed using six closely related three-ringed isomers and metabolites. Effects on growth rate were examined by comparing the average day of emergence of exposed midges with that of controls. Fluctuating asymmetry (FA) in the pecten epipharyngis was examined as a measure of developmental abnormality. Delayed emergence was found at concentrations as low as 2% of the acute LC50, so emergence day appears to be a useful sensitive parameter to quantify life cycle effects. No differences in FA were found between exposed and control larvae, although, in other studies, all compounds have been proven to be genotoxic. The differences in the genotoxic and FA-inducing properties of these compounds indicate that different mechanisms are involved in expressing these adverse effects. This study also illustrates that the choice of the morphological parameter strongly influences the results of developmental disturbance analyses and thus the risk qualification of a potentially hazardous compound.
Assessing model uncertainty for environmental decision making: A case study of the coherence of independently derived environmental quality objectives for air and water
Authors: Ragas Ad M.J , Etienne Rampal S , Willemsen Frank H , Van De Meent Dik
Published: March 2010

Many decisions in environmental management are based on model predictions that are plagued by uncertainty. It is sensible to consider this uncertainty because it can influence the outcome of the decision-making process. This paper outlines a method to assess uncertainty in model predictions in situations in which validation research is difficult or impossible. It is illustrated in a case study of the coherence of independently derived environmental quality objectives (EQOs) for air and water involving the application of a multimedia fate model (SimpleBox). Distinction was made between operational and fundamental uncertainty, which were assessed separately. Operational uncertainty was assessed by quantifying the uncertainties in the input parameters of the model and performing Monte Carlo simulations. Fundamental uncertainty was assessed tentatively by means of a postal questionnaire among scientists and scientifically trained policy makers and representatives of interest groups in the Netherlands. The results indicate that the perceived fundamental uncertainty tends to exceed the calculated operational uncertainty. These results emphasize the importance of considering fundamental uncertainty in environmental decision making. Efforts to improve the quality of coherence testing of independently derived EQOs should aim at reducing the perceived fundamental uncertainty, for example, by defining the coherence criteria of EQOs in measurable attributes, thus facilitating validation research and enabling a more detailed assessment of the fundamental uncertainty.
Liposome—water and octanol—water partitioning of alcohol ethoxylates
Authors: Muuller Markus T , Zehnder Alexander JB , Escher Beate I
Published: March 2010

Liposome—water partitioning coefficients, (Klipws), were determined for eight pure alcohol ethoxylates using equilibrium dialysis and ultracentrifugation. Both methods yielded statistically indistinguishable results. The experimentally determined log Klipws were compared with log Kow values estimated with the fragment method using different literature sources for the fragment constants. Fragments of log Klipw were calculated for the ethoxy group (EO) and the -CH2- units from the experimentally determined data. An additional -CH2- unit causes an average increase of log Klipw by 0.45, and an additional EO causes an average decrease of log Klipw by −0.12. With these fragments, the quality of log Klipw estimations can be improved significantly as compared to simple linear regression of log Klipw versus log Kow. The Klipw values calculated according to the new fragment method for pure compounds and for commercial mixtures are shown to be adequate descriptors for quantitative structure—activity relationships of bioaccumulation, toxicity, and sorption to natural organic material.
Optimization of the methylene blue assay for anionic surfactants added to estuarine and marine water
Authors: George Alison L , White Graham F
Published: March 2010

The existing rapid method for the determination of anionic surfactants in aqueous solutions relies on the association of the cationic methylene blue dye with the anionic surfactant to form an electroneutral complex that is subsequently extracted into chloroform and determined spectrophotometrically. This methylene blue active substance (MBAS) assay suffers from salt interference in estuarine and marine waters due to the high concentration of chloride (Cl-) ions. The interference was shown to arise from the association of Cl- ions with the cationic methylene blue dye, which, although weak, becomes significant at the elevated concentrations of Cl- in marine water. Analysis of the kinetics of the formation and extraction into chloroform of complexes of methylene blue with a typical anionic surfactant (sodium dodecyl sulfate, SDS) and with Cl- ions revealed that the efficacy of the extraction step was critical in yielding reliable data. Based on these results, a modified, simple one—step MBAS method is described that overcomes interference by salt.
Modulation of CYP1A expression in rainbow trout by a technical grade formulation of propiconazole
Authors: Levine Steven L , Oris James T , Denison Michael S
Published: March 2010

In a recent survey of pesticide concentrations in aquatic ecosystems of Central America, the antifungal triazole compound propiconazole was found to be the most widely distributed pesticide. Previously, technical grade propiconazole (TGP) has been shown to modulate cytochrome P450 activity in mammals and birds. The present study investigated the concentration- and timedependent effects of TGP on hepatic cytochrome CYP1A gene expression and catalytic activity in rainbow trout (Oncorhyncus mykiss). The TGP produced both a mixed-pattern response and a biphasic response for CYP1A expression following waterborne exposure. Evidence for inhibitory complex formation with cytochrome P450 may explain the occurrence of the mixed-pattern response. To further characterize the influence of TGP on CYP1A expression, a comparison was made between TGP and analytical grade propiconazole (AGP) with in vivo and in vitro assays. This comparison demonstrated that induction of the CYP1A gene resulted from unidentified compounds in TGP. Since TGP can be coapplied with other agricultural pesticides, either inhibition or induction of CYP1A protein activity by TGP and potentially other cytochrome P450 isoenzymes may lead to unexpected toxicological interactions.
Acute and chronic bioassays with New Zealand freshwater copepods using pentachlorophenol
Authors: Willis Kate J
Published: March 2010

The suitability for laboratory culture and comparative sensitivity of three species of New Zealand freshwater copepod (Calamoecia lucasi Brady, Boeckella delicata Percival, and Mesocyclops cf. leuckarti Claus) to pentachlorophenol (PCP) was assessed. Acute bioassays used two life stages (nauplii and adults). Acute 48-h lethality tests were conducted at 22°C with laboratorycultured animals of all species and at varying temperatures with seasonally collected C. lucasi adults. Mean 48-h median lethal concentration values for nauplii ranged from 52 to 227 μg/L PCP for C. lucasi and B. delicata, respectively, and from 106 to 173 μg/L for adult C. lucasi and M. leuckarti, respectively. The survival rate in controls was ≥95% in acute tests, with the exception of C. lucasi nauplii, in which it was 60%. Mean 48-h median lethal concentration values for seasonally collected C. lucasi adults were significantly higher in summer than in all other seasons. Chronic sublethal tests starting with nauplii <24 h old measured time to metamorphosis. Pentachlorophenol delayed metamorphosis in all species. Chronic toxicity values were 14, 61, and 104 μg/L PCP for C. lucasi, B. delicata, and M. leuckarti, respectively. The mortality rate in controls was also high in C. lucasi sublethal tests (65%), and of the three species, they were the most difficult to culture.
Bioaccumulation tests applied in whole effluent assessment: A review
Authors: de Maagd P Gert-Jan
Published: March 2010

Until recently, the emphasis within whole effluent assessment has been on the application of bioassays for acute and chronic toxicity. Although the need for additional parameters to assess the ecotoxicological hazard and risk of effluents for receiving water systems has been repeatedly advocated, other parameters such as bioaccumulation, genotoxicity, sediment toxicity, and nutrient impacts are seldom addressed. This paper discusses the potential additional value of including bioaccumulation parameters in whole effluent assessment and methods that can be used for routine assessment. It is concluded that screening on the presence of potentially bioaccumulating compounds leads to a more comprehensive hazard assessment and should therefore be included in whole effluent assessment. A chemical method to assess potentially bioaccumulating substances (PBSs) is preferred above methods using organisms or classical group parameters such as extractable organic halogens (EOX). In situ studies with organisms are not feasible for routine assessment for a number of reasons, including cost efficiency and matrix problems. Classical group parameters such as EOX do not relate to bioaccumulation or toxicity. Chemical methods for assessing bioaccumulation are usually presented as integrated methods composed of different procedure steps such as pretreatment, extraction, separation, and detection. However, an optimal method may be constructed by combining procedure steps from different reported methods. Solid phase microextraction combined with high performance liquid chromatography or gas chromatography combined with mass spectrometry is regarded as the preferable method for the assessment of PBSs. Before implementation in whole effluent assessment, however, the method must be carefully validated. Hazard assessment based on bioaccumulation seems feasible. For risk assessment, however, additional information is a prerequisite. Quantitative causal relationships between test assay results and relevant effects on the population and ecosystem level are absent, hampering the desired upgrading from hazard to risk assessment.
Effect of soil contaminant extraction method in determining toxicity using the microtox® assay
Authors: Harkey Gail A , Young Thomas M
Published: March 2010

This project examined the influence of different extraction methods onthe measured toxicityofcontaminatedsoils collected from manufactured gas plant (MGP) sites differing in soil composition and contaminant concentration. Aged soils from a number of MGP sites were extracted using a saline solution, supercritical fluid extraction (SFE), and Soxhlet extraction. Toxicity was assessed using two forms of Microtox® tests: acute aqueous tests on saline and SFE soil extracts and solid-phase tests (SPTs) on soil particles. Microtox SPTs were performed on soils before and after SFE to determine resulting toxicity reduction. Three hypotheses were tested: (1) Toxicity of soil extracts is related to contaminant concentrations of the extracts, (2) measured toxicity significantly decreases with less vigorous methods of extraction, and (3) supercritical fluid extractability correlates with measured toxicity. The EC50s for SPTs performed before and after SFE were not different for some soils but were significantly greater after extraction for other soils tested. The most significant toxicity reductions were observed for soils exhibiting the highest toxicity in both preextraction SPTs and acute aqueous tests. Acute Microtox tests performed on SFE extracts showed significantly lower EC50s than those reported from saline-based extraction procedures. Toxicity of the soils measured by Microtox SPTs was strongly correlated with both SFE efficiency and measures of contaminant aging. Data from this project provide evidence of sequestration and reduced availability of polycyclic aromatic hydrocarbons (PAHs) from soils extracted via physiologically based procedures compared to vigorous physical extraction protocols.
Transfer of carbon and a polychlorinated biphenyl through the pelagic microbial food web in a coastal ecosystem
Authors: Wallberg Petra , Andersson Agneta
Published: March 2010

In order to estimate fluxes of carbon within the microbial community, seawater was collected in a coastal area off Zanzibar Island, Tanzania, during a rainy season (November 1994) and a dry season (September 1996). Diel experiments were conducted in a 24-L polycarbonate bottle and samples were retrieved every third hour over a period of 30 to 33 h. Abundance and production rates of bacteria, nanoflagellates, and microplankton were determined. To determine possible connections between the fluxes of carbon and the fate of 2,2′,4,4′,5,5′-hexachlorobiphenyl International Union of Pure and Applied Chemistry (IUPAC) no. 153, a time-course experiment was conducted after the diel experiment. The initial PCB partitioning was similar in the two experiments, but the subsequent distribution among the organism groups was different. In the rainy season experiment, the PCB concentration in the largest size fraction was almost three times higher than during the dry season experiment. This was in line with results from the diel experiments where the carbon flux through the microbial food web was approximately three times higher during the rainy season than during the dry season experiment. These results suggest that the transfer rate of 2,2′,4,4′,5,5′-hexachlorobiphenyl through the microbial food web is coupled to the carbon flux.
Mutual in vivo interactions between benzo[a]pyrene and tributyltin in brook trout (Salvelinus fontinalis)
Authors: Padrós Jaime , Pelletier Émilien , Reader Stéphanie , Denizeau Francine
Published: March 2010

Tributyltin (TBT), an organometal used as an antifouling biocide, has been reported to inhibit cytochrome P450 (P450) 1A isozyme. Benzo[a]pyrene (BaP), a widespread carcinogenic polycyclic aromatic hydrocarbon, is both metabolized and bioac-tivated to carcinogenic BaP diol-epoxide (BPDE) metabolites primarily by hepatic P450 1A. Hence, TBT may inhibit the metabolism and bioactivation of BaP This study was therefore designed to examine the potential in vivo interactions between BaP and TBT in a model fish. Male brook trout (Salvelinus fontinalis) were given a single intraperitoneal injection of either BaP (10 mg/kg), TBT (10 mg/kg), or both in combination. After 48 h, blood, bile, and liver samples were collected and analyzed for a suite of biomarkers associated with P450 activity, BaP metabolism and bioactivation, and TBT metabolism. The results showed that TBT significantly (p < 0.05; two-way analysis of variance) inhibited (a) the induction of hepatic P450 1A-mediated ethoxyresorufin O-deethylase (EROD) and P450-mediated 3-cyano-7-ethoxycoumarin-O-deethylase (CN-ECOD) activities by BaP, (b) the formation of biliary BaP metabolites, and (c) the formation of (+)-anti-BPDE-plasma albumin adducts as measured by high-performance liquid chromatography/fluorescence. Notably, TBT alone did not inhibit EROD activity but induced CN-ECOD activity (p < 0.05). Gas chromatography/mass spectrometry analysis indicated that the combined BaP + TBT dose resulted in higher levels of dibutyltin metabolites in the bile (p < 0.05). The present study supports the hypothesis that a single, high dose of TBT can antagonize the metabolism and bioactivation of BaP at least by inhibiting the induction of P4501A. On the other hand, BaP unexpectedly potentiated the metabolism of TBT, suggesting that hepatic isoforms other than P4501A may be responsible for TBT metabolism. Finally, this study supports the utility of a biomarker approach to screen potential xenobiotic interactions in aquatic organisms and to obtain mechanistic insights.
Methodology for the evaluation of cumulative episodic exposure to chemical stressors in aquatic risk assessment
Authors: Morton Michael G , Dickson Kenneth L , Waller William T , Acevedo Miguel F , Mayer Foster L , Ablan Magdiel
Published: March 2010

An ecological risk assessment method was developed to evaluate the magnitude, duration, and episodic nature of chemical stressors on aquatic communities. The percent of an ecosystem's species at risk from a designated chemical exposure scenario is generated. In effects assessment, probabilistic extrapolation methods are used to generate estimated safe concentrations (ESCs) for an ecosystem using laboratory toxicity test results. Fate and transport modeling is employed to generate temporal stressor concentration profiles. In risk characterization, area under the curve integration is performed on predicted exposure concentration profiles to calculate a cumulative exposure concentration (CEC) for the exposure event. A correction is made to account for the allowable exposure duration to the stressor ESC. Finally, the CEC is applied to the extrapolation model (curve) of the stressor to predict percent species at risk to the episodic exposure. The method may be used for either prospective or retrospective risk assessments. The results of a retrospective risk assessment performed on the Leadenwah Creek, South Carolina, USA, estuarine community are presented as a case study. The creek experienced periodic episodes of pesticide-contaminated agricultural runoff from 1986 through 1989. Although limited biological data were available for method validation, the risk estimates compared well with the Leadenwah Creek in situ bioassay results.
Offspring fitness inDaphnia: Is theDaphniareproduction test appropriate for extrapolating effects on the population level?
Authors: Hammers-Wirtz Monika , Ratte Hans Toni
Published: March 2010

In the Daphnia reproduction test, the number of living offspring per living parent, mortality, and, occasionally, growth and time to first brood are used as endpoints for the determination of no-observed-effect concentration (NOEC)/lowest-observed-effect concentration (LOEC), or 50% effective concentration (EC50). It is known that chemicals can influence not only the number of neonates but also the offspring size (and, thus, possibly the neonate fitness) in daphnids. Changes in neonate size and fitness have not been routinely recorded in Daphnia reproduction tests, although they are an important factor in population growth. Some of our previous research with some dispersants showed clear effects on offspring quality (smaller neonates with enhanced mortality). We tested one of these dispersants in two different test designs: the reproduction test and a population growth experiment. The results from these two experimental designs differed completely: in the reproduction test, the living offspring number was increased (by up to 10.2 mg/L of the dispersant Dispersogen A) in comparison with the control, whereas in the population growth experiment, the population size was already reduced at concentrations of 1.64 mg/L. A F1-reproduction test, conducted in control medium with neonates born in the reproduction test, showed that neonate fitness was significantly reduced at concentrations of 1.64 mg/L and higher. Therefore, it appears absolutely necessary to take neonate fitness into account if we intend to assess population-level effects. This is easily considered in a population growth experiment but not in the Daphnia reproduction test. To evaluate the fitness of the neonates, an additional test with neonates (F1 test) or another test design (population growth experiment) is necessary.
Fate of 2,4,6-trinitrotoluene in axenic sand culture systems containing smooth bromegrass
Authors: Sun Wen-Hao , Horst Garald L , Drijber Rhae A , Elthon Thomas E
Published: March 2010

Plants have the potential to metabolize the munition 2,4,6-trinitrotoluene (TNT) in contaminated soils, sediments, and natural waters. However, microbial interference must be eliminated to demonstrate an intrinsic capacity for the metabolism of TNT by plants. An axenic sand culture system for smooth bromegrass (Bromus inermis Leyss) was established to investigate the influence of TNT on smooth bromegrass growth and metabolism. Shoot length growth was inhibited by 40% after 14 d of exposure to TNT at 36 mg/L in the sand solution, whereas photosynthetic and respiration rates were similar to controls. Addition of [14C]-labeled TNT to the system resulted in the roots containing 21.3% and the shoots containing 3.8% of the radioactivity. The [14C]TNT in media that contained plants was reduced about 50% compared to media without plants. Trace amounts (0.03%) of the initial [14C]TNT was converted to 14CO2 during a 5-d incubation period. The TNT and its metabolites were observed in root and shoot extracts by radiochromatographic analysis. The major TNT metabolites identified were 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. Previous exposure of the plants to TNT did not increase TNT metabolism or prevent reduction of shoot length growth. From these results we concluded that smooth bromegrass is capable of taking up and metabolizing TNT.
Prominent chlorobornane residues in estuarine sediments contaminated with toxaphene
Authors: Maruya Keith A , Wakeham Stuart G , Vetter Walter , Francendese Leo
Published: March 2010

Soils and sediments contaminated with residues of technical toxaphene may require remedial action to reduce human health and ecological risks. Sediments were collected from a coastal wetland impacted by discharge from a former toxaphene production facility and analyzed by gas chromatography–electron capture detection and conventional and enantioselective gas chromatography-mass spectrometry in the electron capture negative ion mode. The prominent chlorobornanes (CHBs) in all samples were 2-exo,3-endo,6-exo,8,9,10-hexachlorobornane (B6-923 or Hx-Sed) and 2-endo,3-exo,5-endo,6-exo,8,9,10-heptachlorobornane (B7-1001 or Hp-Sed), metabolites of higher chlorinated components of technical toxaphene (CTTs). Pentachlorobornanes, toxaphene homologs not previously reported in environmental samples, and likely precursor CTTs were also detected. Several CHB congeners were enantioresolved, the majority of which exhibited racemic composition. These results indicate that the profile of CHBs persisting in estuarine sediment is highly modified relative to the technical mixture, and also provides strong evidence of in situ reductive dechlorination, a process that if enhanced could act to reduce bioaccumulation and toxicity of sediment-bound CTTs at toxaphene-contaminated sites.
Tissue disposition of benzo[A]pyrene in blue mussel (Mytilus edulis) and effect of algal concentration on metabolism and depuration
Authors: Magnusson Kerstin , Ekelund Rolf , Ingebrigtsen Kristian , Granmo Åke , Brandt Ingvar
Published: March 2010

In vivo metabolism and depuration of benzo [a]pyrene (BaP) was studied in the blue mussel Mytilus edulis. In one experiment, the animals were injected with 3H-BaP and thereafter exposed to either a high (H) or a low (L) concentration of the alga Isochrysis galbana. Mussels were sampled after 2, 4, 8, 16, and 32 d and temporal changes in the metabolite profiles were analyzed using nonpolar and polar solvents. The metabolic fate and the depuration rate of BaP from the two feeding groups were compared. In a second experiment, mussels were exposed to [3H]-BaP or [14C]-BaP either injected or via the surrounding water, and the tissue distribution of radiolabeled compound was studied. The half-life of BaP was 15–17 days and unaffected by the food concentration. The metabolic profile differed slightly between the two treatments. Animals in the L group had a significant peak in the quantity of macromolecular adducts eight days after the injection, whereas the H group had a fairly stable amount of adducts throughout the experimental period. The tissue distribution study revealed that the radiolabeled compound was mainly present in the epithelial cells of the hepatopancreas and the ciliated epithelial cells of the gills. A fraction of the radioactivity was firmly bound.
Interaction of pyrethroids with ion transport pathways present in frog skin
Authors: Cassano Giuseppe , Bellantuono Vito , Quaranta Angelo , Ippolito Cosima , Ardizzone Concetta , Lippe Claudio
Published: March 2010

We measured the ability of deltamethrin and permethrin to stimulate the ion transport operated by the frog skin. Ion transport was monitored by measuring the short-circuit current. Deltamethrin and permethrin, added to the fluid bathing the internal surface of the isolated frog skin, showed a seasonal feature and were more effective in increasing short-circuit current in the period between June and October. Transepithelial influxes and outfluxes of 22Na+ and 36C1− across symmetrical parts of the short-circuited skin were then measured. Deltamethrin was found to increase net Na+ absorption and, to a lesser extent, Cl1 secretion. The presence of a Cl− secretory mechanism is supported by two observations, those being that the short-circuit current value, recorded when deltamethrin and amiloride (inhibitor of Na+ channels) were simultaneously present, was higher than that obtained in the presence of amiloride alone and that bumetanide, a classic inhibitor of Cl− secretion, completely inhibited the component of the Cl− outflux that was induced by the deltamethrin stimulation. The stimulations of short-circuit current respectively caused by deltamethrin (type II pyrethroid) and permethrin (type I) were comparable and similarly affected by indomethacin (an inhibitor of cyclooxygenase) and W7 (an inhibitor of the Ca2+/calmodulin system). These findings suggest that, in frog skin, the cellular mechanism of action of type I and type II pyrethroids is similar.
Organochlorine and trace element contamination in wintering and migrating diving ducks in the southern great lakes, USA, since the zebra mussel invasion
Authors: Custer Christine M , Custer Thomas W
Published: March 2010

Because of the potential for increased trophic transfer of contaminants by zebra mussels (Dreissena sp.) to higher trophic levels, we collected four species of waterfowl (n = 65 ducks) from four locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA, between 1991 and 1993 for organochlorine contaminant and trace element analyses. Geometric mean concentrations of total polychlorinated biphenyls (PCBs) and p, p′-dichlorodiphenyldichloroethylene (DDE) were 1.35 and 0.15 μg/g wet weight in lesser scaup (Aythya affinis) carcasses and were below known effect levels. Total PCBs in 80% of carcasses, however, were above the U.S. Food and Drug Administration's threshold of 3.0 μg/g lipid weight for consumption of poultry. With the exception of selenium, trace elements were also at background or no-effect levels. Selenium concentrations in livers of 95% of lesser scaup, 90% of bufflehead (Bucephala albeola), and 72% of common goldeneye (Bucephala clangula) were in the elevated (>10 μg/g dry wt) or potentially harmful range (>33 μg/g dry wt). The effects of these high selenium concentrations are unknown but should be investigated further based on reproductive effects observed in field and laboratory studies of dabbling ducks and because lesser scaup populations are declining. Concentrations of total PCBs in dreissenid mussels in western Lake Erie were 10 times higher than in the upper Mississippi River but were similar to concentrations in other industrialized rivers in Europe and the United States. Metal concentrations were similar to other industrialized sites where zebra mussels have been sampled.
Mean extinction time of populations under toxicant stress and ecological risk assessment
Authors: Tanaka Yoshinari , Nakanishi Junko
Published: March 2010

Population-level effects of chemical pollutants are evaluated in terms of decrements of mean extinction time of populations. Analytical solutions of the mean extinction time based on the diffusion approximation were applied to published chronic ecotoxicological data provided from life table experiments or population growth experiments. Assuming a fairly large population (a million) with environmental fluctuation of an observed magnitude, chemical exposure with a concentration of 10% of LC50 is expected to cause, on average, an extinction risk of 16% reduction in the mean extinction time, which is equivalent to that induced by a 1.2% reduction of the population size (or habitat area). Although the ecological risk assessment based on mean extinction time has many limitations, it may present a possibility for interpreting the ecological risk of chemical pollutants in the context of population vulnerability.
Effects of short-term oxygen depletion on fish
Authors: Seager John , Milne Ian , Mallett Mike , Sims Ian
Published: March 2010

Laboratory experiments were undertaken to investigate the influences of exposure duration and frequency on the toxicity of short-term pulses of low dissolved oxygen (DO) to fish. For the investigation of exposure duration, rainbow trout (Oncorhynchus mykiss [Walbaum]) and roach (Rutilus rutilus L.) were exposed to a range of DO concentrations in single pulses of 1, 6, or 24 h. For the investigation of exposure frequency, brown trout (Salmo trutta L.) were exposed to 24-h pulses of DO concentrations of 4.0 and 5.5 mg/L at frequencies of once or twice weekly over a period of 75 d. The results suggest that, for a given duration, there is a narrow threshold concentration range above which mortality does not occur and below which mortality rapidly becomes high. This threshold concentration range increases as exposure duration increases. Roach were able to survive lower DO concentrations than trout. Observations on experimental animals following exposure indicated no significant postexposure effects, even at very low DO levels. For the exposure frequencies used here, DO concentration rather than frequency of exposure was the important factor in terms of effect on fish. No significant effects on growth rate were observed but there were significant differences in hemoglobin levels, hematocrit, and organ weights. These results have important implications for the derivation of environmental quality standards aimed at the control of episodic pollution in rivers.