bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity of silver to the marine teleost (Oligocottus maculosus): Effects of salinity and ammonia
Authors: Shaw Joseph R , Wood Chris M , Birge Wesley J , Hogstrand Christer
Published: March 2010

Investigations were conducted to determine the toxicity and define parameters (i.e., ammonia, salinity) that influence the effects of silver on the tidepool sculpin (Oligocottus maculosus). In one series of experiments, static-renewal 168-h toxicity tests were conducted with silver at 32‰(i.e., ambient) and 25‰ salinity seawater. Silver was analyzed in fish that survived these exposures. Toxicity was greater at the lower salinity. The 96-h and 168-h 50% lethal concentration (LC50) values were 3.07 μmol Ag/L (0.331 mg Ag/L) and 1.11 μmol Ag/L (0.119 mg Ag/L) at 25‰ and 6.2 μmol Ag/L (0.664 mg Ag/L) and 4.37 μmol Ag/L (0.472 mg Ag/L) at 32‰ salinity, respectively. There was no correlation between whole-body silver burden and toxicity. Silver uptake increased with exposure concentrations at 25‰ salinity, but at 32‰ whole body accumulation did not exceed that observed for control fish irrespective of the concentrations tested. In another set of experiments, 96-h static-renewal toxicity tests were conducted with silver, ammonia, and combinations of each. The 96-h LC50 for ammonia was 5.9 mmol total ammonia (Tamm)/L (106 mg Tamm/L). When tested in combination, silver toxicity was enhanced and the onset of mortality hastened. Mortality increased in a dose-dependent fashion at 6.35 μmol Ag/L (0.685 mg Ag/L) from 55 to 100% in the presence of ammonia concentrations ranging from 0 to 12.60 mmol Tamm/L (0–226.8 mg Tamm/L). Conversely, the 50% lethal time (LT50) estimated at this level of silver exposure progressively dropped from 5,730 to 1,180 min over the same range of ammonia concentrations.
Bioaccumulation of silver from laboratory-spiked sediments in the oligochaete (Lumbriculus variegatus)
Authors: Hirsch Marianne P
Published: March 2010

A 28-d bioaccumulation study was conducted to assess the potential of silver to bioaccumulate in the oligochaete Lumbriculus variegatus. The oligochaetes were exposed to laboratory-spiked sediments containing approx. 444 mg Ag/kg dry weight for up to 28 d. Fifteen test replicates were prepared by adding 300 adult L. variegatus to 4-L glass beakers containing 1 L of silver sulfide-amended sediment. An equal number of controls were also prepared. After 1, 5, 13, 21, and 28 d of exposure to the sediments, the oligochaetes within each of three test and three control replicate vessels were recovered and counted. The recovered organisms were transferred to dilution water and allowed to purge gut contents for 24 h. The organisms recovered from each replicate vessel at each sampling period were pooled, dried, weighed, and analyzed to determine tissue silver concentrations. By the end of the test, the mean number of oligochaetes recovered from the control and the test sediments increased by 1.8- and 1.9-fold, respectively. The accumulation factor for silver, as silver sulfide, was estimated to be 0.18. This low accumulation factor indicates that contamination of sediments with silver sulfide does not pose a major route of entry of silver into the aquatic food web.
Halogenation and toxicity of the biodegradation products of a nonionic surfactant, nonylphenol ethoxylate
Authors: Maki Hideaki , Okamura Hideo , Aoyama Isao , Fujita Masanori
Published: March 2010

We simulated the formation of halogenated by-products of biodegradation products of a nonionic surfactant, nonylphenol ethoxylate (NPE), and evaluated the toxicity of these by-products. Most NPE derivatives bearing shortened ethylene oxide (EO) chains (abbreviated as NPnEO) and nonylphenol carboxylate (NPnEC) disappeared within 24 h. In both NPnEO and NPnEC, benzene rings are substituted by monobromine. In contrast, chlorine-substituted derivatives were scarcely detected. However, the stoichiometrical bromination of NPnEO and NPnEC was not found. Total amounts of NPnEO, NPnEC, and their bromine-substituted products (BrNPnEO and BrNPnEC, respectively) tended to diminish with increasing level of residual chlorine concentration. Hence, it was suggested that both NPnEO and NPnEC were transformed to unknown by-products. The optimum pH for the formation of both BrNPnEO and BrNPnEC was approximately 7, and these formations decreased remarkably at higher pH. The formation of both BrNPnEO and BrNPnEC was shown to be dependent on the bromide anion concentration but independent of the level of residual chlorine. In the umu assay, a mutagenicity test that uses genetically engineered Salmonella bacteria, neither BrNPnEO nor BrNPnEC showed significant mutagenicity irrespective of metabolic activation by S9-mix. However, both BrNPnEO and BrNPnEC showed higher acute toxicity to Daphnia magna than their nonbrominated precursors, NPnEO and NPnEC. The toxicity of BrNPnEO to Daphnia was higher than that of BrNPnEC.
Sensitivity limits and EC50 values of theVibrio fischeritest for organic micropollutants in natural and spiked extracts from sediments
Authors: Salizzato Michela , Bertato Valentina , Pavoni Bruno , Ghirardini Anna Volpi , Ghetti Pier Francesco
Published: March 2010

Chemical analyses and bioassays were used in conjunction to assess the quality of sediments of the Venice lagoon. Organic micropollutants (polycyclic aromatic hydrocarbons [PAHs] polychlorinated biphenyls [PCBs], and chlorinated pesticides) were extracted from sediment samples and analyzed by gas chromatography after fractionation into classes of compounds. The Vibrio fischeri test was used to assess the acute toxicity of sediment extracts. The test was applied to organic extracts before cleanup and to extracts purified from sulfur and fractionated into single classes of compounds. Extracts before purification were much more toxic than single fractions. In particular, sulfur was toxic to V. fischeri. For PAHs and PCBs the 50% effective concentration (EC50) and EC20 values were determined using natural and spiked extracts (EC50 = 0.5 μg/ml and 1.4 μg/ml, respectively; EC20 = 0.13 μg/ml and 0.17 μg/ml). Sensitivity limits of the method for these compounds were also estimated as was an EC50 value of elemental sulfur dissolved in ethanol (0.022 μg/ml). A mathematical model was used to fit the concentration–response data to a sigmoid curve.
Tentative identification of persistent poly(glycidyl) monofluorooctylphenyl ether nonionic surfactant in river waters and effluent from a secondary wastewater treatment plant
Authors: Yamagishi Tomohiko , Hashimoto Shinya , Otsuki Akira
Published: March 2010

Water samples were collected at two polluted rivers and near the discharge mouth of a large secondary wastewater treatment plant in Tokyo. After surfactants in filtrates were adsorbed onto Amberlite XAD-16 resin and eluted with methanol, the co-adsorbed anionic and cationic surfactants in the eluent were removed with a strong cation- and anion-exchange resin column. Poly(oxyethylene) octylphenyl ether nonionic surfactant was separated using normal-phase high-performance liquid chromatography (HPLC) with UV detection at 280 nm and a pure carbon column after concentration of the eluent by nitrogen gas stream. A relatively large unknown peak in the HPLC chromatogram was fractionated and an attempt was made to identify it by atmospheric pressure chemical ionization and electrospray ionization mass spectrometry. The present study tentatively identified the occurrence of persistent poly(glycidyl) monofluorooctylphenyl ether nonionic surfactants as one of the new persistent organic pollutants in river waters and effluent from a secondary wastewater treatment plant.
Biomonitoring with shrimp to detect seasonal change in river water toxicity
Authors: Shigehisa Hatakeyama , Shiraishi Hiroaki
Published: March 2010

Seasonal changes in toxicity of Kokai River water to a freshwater shrimp (Paratya compressa improvisa) were monitored from 1989 to 1993. A 4-d toxicity test was conducted three times a week from April to August from 1989 to 1993 to measure mortality. Seventeen pesticides were analyzed during the biological monitoring. Expected shrimp mortalities were calculated by adding mortalities caused by each insecticide at the measured concentrations. Shrimp mortalities increased in late May to mid-June and could be attributed to additive effects of insecticides such as pyridaphenthion, malathion, and fenobucarb. Mortalities decreased toward the end of June but increased again from July to mid-August and could be attributed to insecticides such as diazinon or fenobucarb, which drifted directly into the river after aerial pesticide spraying on paddy fields. High mortalities decreased rapidly after heavy rains in August.
Bioavailability of methylmercury to sacramento blackfish (Orthodon microlepidotus): Dissolved organic carbon effects
Authors: Choi Monica Heekyoung , Cech Joseph J , Lagunas-Solar Manuel C
Published: March 2010

The effect of dissolved organic carbon (DOC) on methylmercury (MeHg) uptake across the gills of Sacramento blackfish (Orthodon microlepidotus) was investigated using the Hg-203 radioisotope (half life = 46.9 d). The efficiency of fish gills in extracting MeHg (1.4 ng/L) from water was measured using a McKim-type fish respirometer that separated exposure (inspired) water from expired water. Blackfish gill ventilation and oxygen consumption rates remained constant, while Me203Hg uptake was decreased significantly (p < 0.05) in the presence of DOC (2 and 5 mg C/L). Mean Me203Hg extraction efficiency, uptake rate constant, and blood to inspired water ratio decreased 78%, 73%, and 63%, respectively, with 2 mg C/L of DOC, and 85%, 82%, and 70% with 5 mg C/L DOC, compared to the Me203Hg reference treatment group. Because respiratory parameters remained unchanged, reductions in Me203Hg uptake indicate strong interactions between DOC and Me203Hg. Methyl203Hg levels in fish gills, kidney, and spleen from 2 and 5 mg C/L were significantly lower (p < 0.05) than those observed from the reference treatment group. These reductions in uptake (bioavailability) support the hypothesis that trans-gill transport of Me203Hg is inhibited when it is complexed by DOC in the aqueous medium, decreasing Me203Hg uptake and accumulation in fish organs.
Response of vegetation to volatile pollutants: A delivery system for controlled, quantifiable chronic exposure of foliage
Authors: Love Sean D , Hale Beverley A
Published: March 2010

Little is known about air-to-foliage transfer of volatile organic pollutants: sink strength of leaves and toxicity to the plant via this route have not been widely documented. An exposure system that is capable of repeatedly delivering a range of concentrations of volatilized organic pollutant to foliage under optimal growth and activity conditions is needed. Using naphthalene (a polycyclic aromatic hydrocarbon) as a model contaminant, a steady-state exposure system was developed in which a continuous stream of naphthalene vapor was generated from a chilled permeation tube. This stream was proportionately released into four separate clean airstreams to deliver four discrete concentrations of naphthalene vapor to large cuvettes in which potted plants were sealed. Each cuvette received a total flow rate of 5 L/min. Naphthalene concentration exiting the permeation tube was calculated twofold: using ideal gas laws and from the daily mass loss of the permeation tube. Daily mass loss from the permeation tube and indirect indication of naphthalene concentration by UV light attenuation indicated that the exposure system was capable of maintaining a logarithmic range of naphthalene vapor concentrations over 4 d. Deviation from predicted concentrations was associated with high moisture content of the air supply line used to vent the permeation tube.
Predicting toxicity in marine sediments with numerical sediment quality guidelines
Authors: Long Edward R , Field L Jay , MacDonald Donald D
Published: March 2010

Matching synoptically collected chemical and laboratory bioassay data (n = 1,068) were compiled from analyses of surficial sediment samples collected during 1990 to 1993 to evaluate the predictive ability of sediment quality guidelines (SQGs), specifically, effects range—low (ERL), effects range—median (ERM), threshold effects level (TEL), and probable effects level (PEL) values. Data were acquired from surveys of sediment quality performed in estuaries along the Atlantic, Pacific, and Gulf of Mexico coasts. Samples were classified as either nontoxic (p > 0.05 relative to controls), marginally toxic (p < 0.05 only), or highly toxic (p < 0.05 and response greater than minimum significant difference relative to controls). This analysis indicated that, when not exceeded, the ERLs and TELs were highly predictive of nontoxicity. The percentages of samples that were highly toxic generally increased with increasing numbers of guidelines (particularly the ERMs and PELs) that were exceeded. Also, the incidence of toxicity increased with increases in concentrations of mixtures of chemicals normalized to (divided by) the SQGs. The ERMs and PELs indicated high predictive ability in samples in which many substances exceeded these concentrations. Suggestions are provided on the uses of these estimates of the predictive ability of sediment guidelines.
Comparative developmental toxicity of planar polychlorinated biphenyl congeners in chickens, American kestrels, and common terns
Authors: Hoffman David J , Melancon Mark J , Klein Patrice N , Eisemann John D , Spann James W
Published: March 2010

The effects of polychlorinated biphenyl (PCB) congeners, PCB 126 (3,3′,4,4′,5-pentaCB) and PCB 77 (3,3′4,4′-tetraCB), were examined in chicken (Gallus gallus), American kestrel (Falco sparverius), and common tern (Sterna hirundo) embryos through hatching, following air cell injections on day 4. PCB 126 caused malformations and edema in chickens starting at 0.3 ppb, in kestrels at 2.3 to 23 ppb, but in terns only at levels affecting hatching success (44 ppb). Extent of edema was most severe in chickens and least in terns. Defects of the beak were common in all species but with crossed beak most prevalent in terns. Effects on embryo growth were most apparent for PCB 126 in chickens and kestrels. The approximate 50% lethal dose (LD50) for PCB 126 in chickens was 0.4 ppb, in kestrels was 65 ppb, and in terns was 104 ppb. The approximate LD50 for PCB 77 in chickens was 2.6 ppb and in kestrels was 316 ppb. Induction of cytochrome P450 associated monooxygenase activity (ethoxyresorufin-O-dealkylase activity) by PCB 126 in chick embryo liver was about 800 times more responsive than in tern and at least 1,000 times more responsive than in kestrel. High concentrations of PCB 126 found in bald eagle eggs are nearly 20-fold higher than the lowest toxic concentration tested in kestrels. Concentrations of PCB 126 causing low-level toxic effects in common tern eggs are comparable to highest levels in common terns and Forster's terns in the field, suggesting additional involvement of other compounds in the Great Lakes.
Effect of pH on the toxicity and biodegradation of pentachlorophenol by Sphingomonas sp strain P5 in nutristat culture
Authors: Rutgers Michiel , van Bommel Sander , Breure Anton M , van Andel Johan G , Duetz Wouter A
Published: March 2010

A polychlorinated-phenol degrading bacterium, Sphingomonas sp. strain P5, was grown in nutristat culture (i.e., a continuous culture at a controlled substrate concentration) with pentachlorophenol (PCP) as the sole carbon and energy source. During steady state conditions, the effect of the medium pH on the growth of strain P5 on PCP was established. At lower pH values PCP exhibited a stronger toxicity than at higher pH values. Inhibition of the growth of strain P5 by PCP was correlated to the concentration of the undissociated phenol in the system, rather than to the dissociated or total PCP concentration. The results indicate that acidification of natural environments may enhance the toxicity of chlorophenols and suggest that treatments to increase environmental pH may reduce risk of chlorophenol toxicity at acidified sites.
Photolytic and microbial degradation of 3,5,6-trichloro-2-pyridinol
Authors: Feng Yucheng , Minard Robert D , Bollag Jean-Marc
Published: March 2010

The photolytic and microbial degradation of 3,5,6-trichloro-2-pyridinol (TCP), a metabolite of the insecticide chlorpyrifos and the herbicide triclopyr, has been investigated. TCP (80 mg/L) was decomposed to nondetectable levels within 2 h of ultraviolet irradiation. Release of 14CO2 and chloride ion was observed; however, approximately 60% of the initial radioactivity remained in the solution. Dichlorodihydroxypyridine isomers and reductive dechlorination products were found as intermediate products of TCP photolysis. It was proposed that both hydrolytic and reductive dechlorination occurred during photodegradation of TCP. Although TCP can be degraded via photolysis, many degradation products remained in the aqueous medium and only some of them, the reductive dechlorination products, can be mineralized by Pseudomonas sp. ATCC 700113. The degradation of the parent compound, TCP, by Pseudomonas sp. ATCC 700113 also appears to involve a reductive dechlorination mechanism. A consortium of microorganisms may be needed if a treatment process combining microbial and photolytic activity is to be used to remove TCP in industrial wastewater.
In vitro digestive fluid extraction as a measure of the bioavailability of sediment-associated polycyclic aromatic hydrocarbons: Sources of variation and implications for partitioning models
Authors: Weston Donald P , Mayer Lawrence M
Published: March 2010

In vitro extraction of contaminated sediments using the digestive fluid of a deposit-feeding polychaete has recently been proposed to study contaminant bioaccumulation mechanisms and perhaps to better quantify the bioavailable contaminant fraction. This approach was evaluated using digestive fluid from the polychaete Arenicola brasiliensis and six marine sediments containing both spiked radiolabeled polycyclic aromatic hydrocarbons (PAHs) and in situ–contaminated unlabeled PAHs. The proportion of total contaminant extracted by digestive fluid from each sediment varied from 22 to 71% and 13 to 52%, for phenanthrene and benzo[a]pyrene, respectively. The proportions of contaminant solubilized were inversely correlated with the sediments' organic carbon content. The extent of PAH solubilization among sediments by A. brasiliensis digestive fluid was highly correlated with that of digestive fluid from the echiuran Urechis caupo and appears to be a consequence of surfactant properties of the fluids rather than of their enzymatic activity. The proportion of PAHs solubilized in vitro was similar to in vivo measurements of solubilization for contaminant exposures lasting about 24 h. However, with continued exposure, in vivo PAH concentrations in the digestive fluid increased fivefold, suggesting that digestive fluid is retained in the gut longer than sediment and thus accumulates PAHs through sequential digestion of many gut volumes. This phenomenon may enhance contaminant fugacity in the gut and increase the potential for bioaccumulation or toxicity.
Accumulation of dietary methylmercury in the testes of the adult Brown Norway rat: Impaired testicular and epididymal function
Authors: Friedmann Andrew S , Chen Haolin , Rabuck Lorrine D , Zirkin Barry R
Published: March 2010

The widespread consumption of fish containing elevated concentrations of methylmercury has prompted concern over the health effects of such a diet. Previous studies with rodents have indicated that exposure to dietary mercury (Hg) impairs male reproductive health. However, adverse effects were observed following doses in the range of milligrams per kilogram of body weight, whereas typical human consumption in the United States is in the range of micrograms per kilogram of body weight. This study examined the effects of dietary Hg on male rats using levels of the metal that are more similar to those typically consumed by humans. For 19 weeks, adult male Brown Norway rats were administered methylmercury twice weekly at 0.8, 8.0, or 80 μg/kg. Intratesticular testosterone levels in the high-dose group were reduced by 44%, suggesting that steroidogenesis in these animals was dramatically impaired. Although sperm production was not significantly affected, numbers of sperm in the cauda epididymides of the high-dose group were reduced by 17%. Furthermore, there was a negative correlation between fertility and testicular Hg content. These results raise the possibility that exposure to Hg at levels consumed by humans may result in steroidogenic impairment, reduced sperm counts, and fertility problems.
Sediment quality thresholds: Estimates from hockey stick regression of liver lesion prevalence in english sole (Pleuronectes vetulus)
Authors: Horness Beth H , Lomax Daniel P , Johnson Lyndal L , Myers Mark S , Pierce Susan M , Collier Tracy K
Published: March 2010

Comprehensive, integrative assessments of coastal sediment quality are best effected by using large, diverse data sets that include measures of biological dysfunction observed in association with chronic exposure to sediment contaminants. Under the auspices of the National Oceanic and Atmospheric Administration's National Status and Trends Program, the National Benthic Surveillance Project accumulated a database of synoptic sediment contaminant concentrations and indices of biological effects that were measured in indigenous animals collected during field surveys conducted from 1984 to 1994. This compilation of data provided the opportunity to develop a new approach for determining sediment quality criteria to add to the current repertoire of environmental assessment tools. Using a two-segment hockey stick regression, statistically significant chemical thresholds of biological effects were estimated for hepatic lesion prevalences in English sole (Pleuronectes vetulus, formerly Parophrys vetulus) in relation to sediment concentrations of polycyclic aromatic hydrocarbons. These threshold estimates are notably lower than many of those reported for other techniques. Application of this relatively simple dose-response model to subacute, chronic effects that are involved in hepatocarcinogenesis and associated with sediment toxicant content (1) reflects the link between toxicopathic disease progression and conditions observed in benthic fish exposed to contaminants and (2) provides endpoints for assessing sediment quality contaminant concentrations that are not necessarily acutely fatal but may have long-term health implications for populations that are chronically exposed.
Chemical stress and metabolic rate in aquatic invertebrates: Threshold, dose–response relationships, and mode of toxic action
Authors: Penttinen Olli-Pekka , Kukkonen Jussi
Published: March 2010

Four aromatic compounds were evaluated in laboratory studies to investigate their accumulation and toxicant-induced changes in the rate of heat dissipation in the freshwater invertebrates Chironomus riparius and Lumbriculus variegatus. The sublethal energetic response detected by direct calorimetry was related to tissue chemical concentration by the threshold model and an attempt was made to apply the critical body residue (CBR) concept. Below the compound-specific tissue threshold concentration or CBR, no correlations were found between the dose and the metabolic rate, and the slopes of the regression were close to zero. Above the threshold, depending on the chemical, metabolic rate either increased or decreased. An increase in heat output produced by 2,4-dinitrophenol (2,4-DNP), pentachlorophenol (PCP), and 2,4,5-trichlorophenol (2,4,5-TCP) was closely correlated with the dose. The order of toxicity for these phenols was 2,4-DNP = PCP > 2,4,5-TCP, which reflects the interaction of compounds' lipophilicities and acidities and their combined influence on bioaccumulation and effects on the energy-transducing membrane by uncoupling oxidative phosphorylation. A decrease in the heat output caused by 1,2,4-trichlorobenzene (1,2,4-TCB) was more variable relative to dose. Also, 1,2,4-TCB required a much higher molar tissue threshold concentration (∼2.0 μmol/g wet weight) than required by phenols to generate the response. Both the metabolic response and the chemical threshold value were those expected to result from narcosis. Results suggest that calorimetric measures can identify not only the integrated physiologic response but also have some resolution of the mechanism of toxic effects.
Decreased transpiration in poplar trees exposed to 2,4,6-trinitrotoluene
Authors: Thompson Phillip L , Ramer Liz A , Guffey Aaron P , Schnoor Jerald L
Published: March 2010

This article discusses the effects of various concentrations of the explosive 2,4,6-trinitrotoluene (TNT) on the transpiration of hybrid poplar trees growing in hydroponic media. Transpiration was measured daily by gravimetric means. The rapid removal of TNT from hydroponic solutions was a result of plant uptake and required a daily dosage of TNT to ensure a relatively constant exposure over time. Transpiration decreased with increasing TNT concentrations ≥5 mg/L. Decreases in transpiration were accompanied by leaf chlorosis and abscission. A comparison between a laboratory study and a pilot-scale experiment showed good scale-up potential.
Zooplankton population and community responses to the pesticide azinphos-methyl in freshwater littoral enclosures
Authors: Sierszen Michael E , Lozano Stephen J
Published: March 2010

We tested the effects of four concentrations (0.2, 1.0, 4.0, and 20.0 μg/L) of the organophosphorus insecticide azinphosmethyl on natural zooplankton communities using littoral ecosystem enclosures. Individual taxa and major zooplankton groups (cladocerans, copepods, and rotifers) exhibited concentration-dependent responses, with most of the significant effects at the two highest concentrations. Analyses of population abundance were more sensitive to the effects of azinphos-methyl than were analyses of major zooplankton groups. Principal component analysis of communities differentiated the contributions of cladocerans, copepods, and rotifers to total community variance. The highest principal components were associated with cladocerans, the group also identified by univariate statistics to be most sensitive to azinphos-methyl. Ordination using the first two principal components depicted the multivariate status of the zooplankton communities through time and showed concentration-dependent effects and recovery from the pesticide at the community level. Principal component ordination was a more sensitive metric of community-level effects than was taxon richness. Communities in the highest treatment concentration had not fully recovered by the last sampling date, 78 d after treatment.
Biochemical and histological responses in rainbow trout (Oncorhynchus mykiss) exposed to 2,3,4,7,8-pentachlorodibenzofuran
Authors: Brown, Scott B , Delorme Peter D , Evans Robert E , Lockhart W Lyle , Muir Derek C.G , Ward Fred J
Published: March 2010

Rainbow tout were given an intraperitoneal injection of corn oil containing 0 or 8.8 nmol (3 μg) [14C]2,3,4,7,8-pentachlorodibenzofuran (P5CDF)/kg and were then held on a light cycle that induced spawning 10 months later. At 5- to 6-week intervals, blood samples were collected to monitor plasma levels of 17β-estradiol (E2), testosterone (T), thyroxine (T4), 3,5,3′-triiodo-L-thyronine (T3), and calcium; packed cell volume (PCV); and differential blood cell counts. Fish were sacrificed after spawning to examine tissue P5CDF concentration, liver ethoxyresorufin-O-deethylase (EROD), liver vitamins (retinoids and tocopherol), histology (liver, thyroid), and growth parameters. The P5CDF injections produced tissue 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentrations comparable to those reported in salmonids from contaminated areas. Highest P5CDF concentrations occurred in gut and liver, but muscle accounted for the greatest proportion of the dose. Plasma hormone and calcium concentrations followed predicted seasonal patterns in both control and exposed fish. PCV was unchanged by repeated blood sampling but differential blood cell counts showed adaptive responses to blood removal. The P5CDF exposure caused transient reductions in circulating lymphocytes and elevated EROD. Additionally, P5CDF increased liver size and depleted retinoid stores in male fish. Liver histology, somatic growth, and gonadal development were unaltered by P5CDF during the first reproductive cycle after exposure.
Effects of organism allocation on toxicity test results
Authors: Davis Robert B , Bailer A John , Oris James T
Published: March 2010

The purpose of this study was to investigate the effect of nonrandom allocation of organisms to treatments in aquatic toxicity tests on lethal concentration estimates. Random allocation of organisms is prescribed to avoid the introduction of systematic bias in these tests; however, completely random assignment is usually impractical. A source of systematic bias in a nonrandom allocation scheme is the potential inverse relationship between organism hardiness and the order in which organisms are captured for assigning to treatment (i.e., less hardy and hence more sensitive individuals are captured first). A Monte Carlo simulation experiment was performed to examine such an inverse relationship for a variety of random allocation schemes, focusing on the mortality endpoint in the fathead minnow larval survival and growth toxicity test. Results of the computer simulation experiment indicated that nonrandom allocation of organisms can produce significant bias in estimates of lethal concentration values. Any attempt at randomization resulted in approximately unbiased estimates of lethal concentration values; however, variance of the estimates increased as allocation schemes deviated from the completely random allocation. This study illustrates the importance of proper training of laboratory personnel to implement some form of random organism allocation. Furthermore, many partial random allocation schemes (i.e., those allocating more than one organism at a time) may still yield unbiased estimates of potency endpoints.
Polybrominated diphenyl ethers and hexabromocyclododecane in sediment and fish from a Swedish River
Authors: Sellström Ulla , Kierkegaard Amelie , de Wit Cynthia , Jansson Bo
Published: March 2010

Fish and sediments from several places along the Swedish River Viskan, sampled in 1995, were analyzed for polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). The samples were collected up- and downstream from several possible point sources (textile industries) for these compounds. Tetrabromodiphenyl ethers (TeBDEs), pentabromodiphenyl ethers (PeBDEs), and decabromodiphenyl ether (DeBDE [BDE209]) were found in sediment. Tetrabromodiphenyl ethers and PeBDEs were also found in fish. Hexabromocyclododecane was identified in sediment and fish. Large fish to sediment ratios for TeBDE, PeBDEs, and HBCD indicate that these are highly bioavailable, whereas BDE209 seems not to be as bioavailable. The lowest PBDE and HBCD levels were found upstream of the industries and concentrations generally increased progressively further downstream as more industries were passed. This is in agreement with earlier investigations of PBDEs in fish from the same river. Many brominated compounds are photolabile, which can complicate their analysis. Under the conditions used in this investigation it was observed that BDE209 in a solvent that was subject to the clean-up procedure partly decomposed to compounds with shorter retention times, whereas BDE209 seemed to be stable in the sample extracts. Another matrix effect could be observed in the increased sensitivity obtained for some of the investigated compounds in fish and sediment extracts as compared to standard solutions. This effect may obscure analytical results obtained with electron capture mass spectrometric detections.
Influence of growth conditions on the results obtained in algal toxicity tests
Authors: Mayer Philipp , Frickmann Jesper , Christensen Erik R , Nyholm Niels
Published: March 2010

The influence of test conditions on results from algal growth inhibition tests was investigated for the toxicants atrazine, 3,4-dichloroaniline, 3,5-dichlorophenol, and potassium dichromate. Emphasis was put on the following four main factors: light, temperature, nitrogen source, and pH. The green alga Selenastrum capricornutum was grown in batch cultures, and the toxic response was measured as reduction in average growth rate, relative to controls. Multifactor experiments were carried out to investigate the effects of the above four factors as well as the interactions between them: light intensity (44 and 198 μE/m2/s), temperature (16 and 26°C), nitrogen source (NH +4 and NO −3), and pH of the medium (7.5 and 8.6). Within the data set generated, the highest and lowest median effective concentration estimate differed by a factor of 3.8. The sensitivity of the test system to 3,4-dichloroaniline, potassium dichromate, and 3,5-dichlorophenol was less under light limitation than under light saturation. Conversely, with the photosynthetic inhibitor atrazine a reduced sensitivity was found at high light intensity, which, however, was high enough to cause slight photoinhibition. The inhibitory response to the weak organic acid 3,5-dichlorophenol was less at the high than at the low pH level, which stems from the fact that neutral species of ionizable compounds are usually more toxic than charged species. No effect of the nitrogen source on inhibitory responses could be ascertained, and temperature influenced the results only indirectly by interacting with light (the saturation intensity increases with temperature). It is concluded that the light intensity in standardized algal toxicity tests could preferably be increased to achieve light-saturated photosynthesis as this may potentially reduce test result variability.
Rapid toxicity assessment of sediments from estuarine ecosystems: A new tandem in vitro testing approach
Authors: Johnson B Thomas , Long Edward R
Published: March 2010

Microtox® and Mutatox® were used to evaluate the acute toxicity and genotoxicity, respectively, of organic sediment extracts from Pensacola Bay and St. Andrew Bay, two estuaries that cover about 273 and 127 km2, respectively, along the Gulf coast of Florida, USA. The sensitivity and selectivity of these two bioluminescent toxicity assays were demonstrated in validation studies with over 50 pesticides, genotoxins, and industrial pollutants, both as single compounds and in complex mixtures. The 50% effective concentration (EC50) values of insecticides, petroleum products, and polychlorinated biphenyls determined by Microtox all tended to group around the mean EC50 value of 1.2 (0.8) mg/L. The polycyclic aromatic hydrocarbon sensitivity of Mutatox was in general similar to that reported in the Ames test. Surficial sediment samples were collected, extracted with dichloromethane, evaporated and concentrated under nitrogen, dissolved in dimethyl sulfoxide, assayed for acute toxicity and genotoxicity, and compared with reference sediments. Samples with low EC50 values, and determined to be genotoxic, were detected in Massalina Bayou, Watson Bayou, East Bay, and St. Andrew Bay–East in St. Andrew Bay as well as Bayou Grande, Bayou Chico, and Bayou Texar in Pensacola Bay. An overview of these data sets analyzed by Spearman rank correlation showed a significant correlation between acute toxicity and genotoxicity (p < 0.05). Microtox and Mutatox in tandem was a sensitive, cost-effective, and rapid (<24 h) screening tool that identified troublesome areas of pollution and assessed the potential sediment toxicity of lipophilic contaminants in aquatic ecosystems.
Calibrating the uptake kinetics of semipermeable membrane devices using exposure standards
Authors: Booij Kees , Sleiderink Hedwig M , Smedes Foppe
Published: March 2010

Organic contaminant exchange kinetics between semipermeable membrane devices (SPMDs) and water were studied in two suspensions of estuarine and marine sediments under conditions of high and low turbulence over a period of 56 d. Prior to exposure, the SPMDs were spiked with a number of exposure standards not occurring in the environment. The release rate of these compounds was used as an independent measure of the exchange kinetics between the SPMD and water. The uptake rates of chlorobenzenes, polychlorinated biphenyls, (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were lower by a factor of three under conditions of low turbulence. For compounds with a log octanol–water partition coefficient (Kow) > 5.5 the uptake rate was constant during the entire period. Within each compound class, uptake rate constants correlated well with log Kow. The uptake rate constants of PAHs were lower than those of PCBs and chlorobenzenes by a factor of 10, but these estimates probably are artificially low due to an overestimation of the aqueous PAH concentrations. Release rate constants of the exposure standards fell within the range of the uptake rate constants of chlorobenzenes and PCBs, although with poor precision. Suggestions for improving the measurement of exchange rate constants of exposure standards are presented. The role of triolein in the exchange kinetics is shown to be minor.
Effect of pH on complexation of Fe(III) with fulvic acids
Authors: da Silva Joaquim C G Esteves , Machado Adélio A S C , Oliveira César J S
Published: March 2010

The interaction of Fe(III) with two samples of fulvic acids (FAs) extracted from a pinewood soil (FA2: horizon 0–10 cm; FA3: horizon 10–25 cm) was monitored by synchronous fluorescence (SyF) spectroscopy at four pH values (3, 4, 5, and 6). Spectral data were preprocessed by SIMPLISMA, a self-modeling curve-resolution method, and from the calculated quenching profiles, equilibrium parameters for the interaction of Fe(III) and FAs were obtained (conditional stability constants [Kcs] and ligand site concentrations). The calculated log Kcs were (I = 0.1 M KNO3; standard deviation in parentheses): FA2, pH = 3, 4.9 (2), pH = 4, 4.7 (2), pH = 5, 5.1 (4), and pH = 6, 5.1 (1); FA3, pH = 3, 5.48 (1); pH = 4, 4.96 (7), pH = 5, 4.89 (1), and pH = 6, 5.1 (2), where I is the ionic strength. These results show that FA forms quite stable soluble complexes with Fe(III) in the acid pH range.
The functional integrity of northern leopard frog (Rana pipiens) and green frog (Rana clamitans) populations in orchard wetlands. I. Genetics, physiology, and biochemistry of breeding adults and young-of-the-year
Authors: Harris Megan L , Bishop Christine A , Struger John , van den Heuvel Michael R , Van Der Kraak Glen J , Dixon D George , Ripley Brian , Bogart James P
Published: March 2010

Northern leopard frogs (Rana pipiens) and green frogs (Rana clamitans) were evaluated at eight wetland sites, four of which were within apple orchards, to determine if environmental changes associated with orchard management affected measured biological parameters. Size, age, genetic variation, condition indices, levels of circulating steroid hormones, 7-ethoxyresorufin-O-deethylase activity (EROD), and organochlorine and organophosphorus residues in breeding males sampled at pond sites in orchards were compared to the same parameters measured in breeding males from reference sites. Also, the size and physiological condition of young-of-the-year captured in orchard and reference ponds were compared. No evidence of a reduction in genetic variation was found in populations of either species at any sites, but unexpectedly high average heterozygosity values (0.191–0.282) in concert with low overall fixation indices (0.012–0.059) in adults of both species did suggest that pond populations were interacting with neighboring populations in nonorchard habitats. Few significant differences in levels of circulating steroid hormones or condition indices of breeding males were found among sites. Significant EROD induction in male green frogs collected from one orchard site during one sampling event was the only indication that a metabolic challenge due to presence of cytochrome P450-inducing toxicants may have existed, whereas elevated concentrations of organochlorines (dichlorodiphenyltrichloroethane [DDT]- or endosulfan-related) in green frog tissues suggested that frogs at three orchard sites were taking up pesticides. Significant differences in size of equivalent-age male and juvenile leopard frogs and green frogs occupying different study sites suggested that suboptimal habitat characteristics existed at one or two of the four orchard sites. However, site-specific habitat deficiencies could not be related to orchard study sites in general, and, thus, wetlands in apple orchards appeared to provide viable breeding habitat for both northern leopard frogs and green frogs.
Reproduction and polychlorinated biphenyls inFundulus heteroclitus(Linnaeus) from new bedford harbor, massachusetts, USA
Authors: Black Dianne E , Gutjahr-Gobell Ruth , Pruell Richard J , Bergen Barbara , Mills Lesley , McElroy Anne E
Published: March 2010

This investigation evaluated polychlorinated biphenyl (PCB) accumulation, survival, and reproduction in Fundulus heteroclitus from four stations along a gradient of increasing sediment contamination from West Island in Buzzards Bay, Massachusetts, USA, to the most contaminated area of the New Bedford Harbor, Massachusetts, USA, Superfund site. Fish collected during their natural spawning season were held in the laboratory for 5 weeks. Liver concentrations of non-ortho- and mono-ortho-PCBs averaged 0.461, 9.48, 20.8, and 29.3 μg/g dry weight, with dioxin toxic equivalent concentrations (TEQs) of 0.006, 0.132, 0.543, and 1.56 ng/g; differences among stations were statistically significant. Females from two stations within the Superfund site had significantly greater mortality (30 and 23%) compared to those within West Island (0%), and growth was reduced. Progeny of fish from the most contaminated station exhibited significantly reduced survival (49%) and greater incidence of spinal abnormalities (26%) compared to those from West Island (70% survival, 7% spinal abnormalities). No differences in egg production or food consumption were observed. A significant residue-effect relationship was found between TEQs of liver PCBs and female mortality, consistent with that determined previously from laboratory exposures and validating TEQ as an effects indicator. Embryo and larval survival were inversely related to maternal liver TEQ.
Evaluation of log KOW and tissue lipid content as predictors of chemical partitioning to fish tissues
Authors: Bertelsen Sharon L , Hoffman Alex D , Gallinat Carol A , Elonen Colleen M , Nichols John W
Published: March 2010

In vitro equilibrium chemical partition coefficients were determined for six chemicals in selected tissues from four species of fish. Log-transformed values were then regressed in stepwise fashion against chemical log octanol/water partition coefficient (Kow) and the log of tissue lipid content to derive a series of linear one- and two-variable models. Equations derived for fat indicate that n-octanol is a good surrogate for nonpolar lipid in the range of chemical log Kow tested (1.46 < log Kow < 4.04). These equations also support the conclusion that previously developed Kow-bioconcentration factor relationships are largely a reflection of chemical accumulation in fat. Fitted slope and intercept terms for “lean” tissues differed from those expected from chemical partitioning to lipid only and were instead consistent with the suggestion that partitioning to nonlipid-nonwater cellular constituents contributes substantially to chemical accumulation. A general equation is presented for prediction of tissue/water and blood/water partitioning from chemical log Kow and tissue (or blood) lipid content. It is suggested, however, that tissue- and blood- specific equations be used to estimate the tissue/blood partitioning relationships needed for kinetic modeling efforts.
Biodegradation of resorcinol and catechol by denitrifying enrichment cultures
Authors: Milligan Peter W , Häggblom Max M
Published: March 2010

We examined the anaerobic degradation of catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene), which are widely used industrial reagents and central intermediates in the biodegradation of numerous aromatic compounds. Anaerobic denitrifying enrichments were established with sediments from an estuarine tidal strait in New Jersey, USA. The three dihydroxybenzene isomers were provided as a sole carbon source in separate enrichment series. Resorcinol- and catechol-degrading consortia used their respective substrates over repeated feedings. Initial loss of hydroquinone was observed, but activity could not be maintained. The degradation of resorcinol and catechol was coupled to denitrification and was dependent on nitrate or nitrite as an electron acceptor. Nitrate consumption and N2 production corresponded to the stoichiometric values predicted for the oxidation of dihydroxybenzenes to CO2.
Suppression of chlorothalonil degradation in soil after repeated application
Authors: Motonaga Kei , Takagi Kazuhiro , Matumoto Satoshi
Published: March 2010

Mechanisms of degradation suppression of chlorothalonil after repeated application were investigated. Under laboratory conditions, soil was treated sequentially with 40 mg/kg dry weight of chlorothalonil. This resulted in the degradation suppression of chlorothalonil and accumulation of the metabolite 4-hydroxy-2,5,6-trichloroisophthalonitrile (TPN-OH) in soil. After pretreatment with three kinds of chlorothalonil metabolite, only TPN-OH was found to suppress chlorothalonil degradation in soil. After the pretreatment of TPN-OH, residual chlorothalonil in soil at 1 week after application was 9 to 11% higher than those with pretreatment with other metabolites and control. The TPN-OH pretreatment also suppressed soil respiration and TPN-OH was more persistent in soil than chlorothalonil, indicating that toxicity of residual TPN-OH may suppress the degradation of chlorothalonil in soil.
Effects of tributyltin, linear alkylbenzenesulfonates, and nutrients (nitrogen and phosphorus) on nucleoid-containing bacteria
Authors: Prior Susanne , Riemann Bo
Published: March 2010

Effects of tributyltin (TBT) and linear alkylbenzenesulfonate (LAS) on the number of nucleoid-containing bacteria (NCB) were examined in 15 marine enclosures situated in Knebel Vig, Denmark. Nucleoid-containing bacteria were enumerated using a newly revised methodological approach including glutaraldehyde fixed 4′,6′ diamidino-2-phenylindole (DAPI) preparations rinsed with 2-propanol. Additions of TBT (0.0025–9.7 nM) reduced the number of NCB up to 62%, whereas additions of LAS (15 μM) increased the numbers. Total counts were not affected by the two toxicants. Values of no-observed-effect concentration, lowest-observed-effect concentration, and concentration at 30% effectiveness for TBT on NCB were 0.020, 0.16, and 0.0036 nM, respectively. These values are much lower than those previously reported by other techniques and are similar to or lower than TBT concentrations measured in harbors and coastal sea regions, suggesting that natural bacterial assemblages in many marine environments are toxified by TBT. Additions of nutrients stimulated both total counts (twofold) and NCB (fourfold), whereas addition of LAS + nutrients stimulated only NCB. Results from two diel studies demonstrated that NCB varied more on a diel scale than did total counts. Nevertheless, the effects of the two toxicants on NCB were significantly higher than the measured diel changes, suggesting that NCB can be used as a sensitive parameter to test effects of toxicants on pelagic ecosystems.