bluuebunny/crossref_metadata_2025 huggingface dataset:
Uptake, elimination and tissue distribution of dietary and aqueous cadmium by rainbow trout (salmo gairdneri richardson) and lake whitefish (coregonus clupeaformis mitchill)
Authors: Harrison S. E. , Klaverkamp J. F.
Published: March 2010

Rainbow trout (Salmo gairdneri) and lake whitefish (Coregonus clupeaformis) were exposed for 72 d to 109Cd in pelletized commercial trout food or in the water in a continuous-flow water exposure system. Blood, gill, gut, liver, kidney, muscle, skin, feces and gut contents were sampled from 40 fish in each group during the exposure phase and from 20 fish in each group during the subsequent 56-d depuration period. Gill accumulated the highest cadmium concentrations. After 56 d of depuration, most of the cadmium in food-exposed fish of both species was in the kidney, gut and liver, but water-exposed fish retained most of the cadmium in gill and kidney. Whole-body concentration factors (L/kg wet weight tissue) after 72 d of exposure for water-exposed fish were 55 for rainbow trout and 42 for whitefish. Whole-body bioconcentration factors after 72 d of exposure for food-exposed fish were less than 1 (kg food/kg dry weight tissue). Both species accumulated significantly greater proportions of the cadmium dose from food than from water. The percentages of the cadmium dose accumulated after 72 d of water exposure were 0.15% for trout and 0.11% for whitefish, while for food exposure the values were 1.03% for trout and 1.01% for whitefish. A simple two-compartment kinetic model was fitted to the data. Equilibrium cadmium bioconcentration factors for aqueous exposure were estimated to be 161 for rainbow trout and 51 for lake whitefish. Biological half-times for depuration ranged from 24 to 63 d.
Acute colonization study of polychlorinated biphenyl-degrading pseudomonads in the mouse intestinal tract: Comparison of single and multiple exposures
Authors: George Susan E. , Kohan Michael J. , Claxton Larry D. , Walsh Debra B.
Published: March 2010

The coprophagic behavior of rodents has been used in a model examining the potential health effects of environmentally released microorganisms. Mutant polychlorinated biphenyl (PCB) degrading pseudomonads, isolated from a commercial product for PCB elimination, were used to evaluate the method. The PCB-degrading component of the product was composed of one Pseudomonas maltophilia and three Pseudomonas aeruginosa strains enhanced for PCB degradation through nitrosoguanidine mutagenesis. Multiple ingestions of the biodegraders were compared with a single exposure. The direct health effects monitored were changes in weight, appetite and overall appearance. The indirect health effects monitored included recovery of the organisms from intestinal contents as well as competition with and alteration of the normal intestinal flora. When animals received a single dose by gavage of 109 colony forming units of an individual Pseudomonas sp., none of the four dosed strains were detected 14 d after dosing when animals were housed in metabolism cages. The use of these metabolism cages, which had wire flooring, limited coprophagy. When animals were housed in conventional cages, which allowed coprophagy, two of the four PCB degraders tested were recovered (104/g intestine). The lactose-fermenting and total aerobic counts were unaffected when animals received a single dose of the biodegrader. In the multiple exposure model, P. maltophilia altered the lactose-fermenting population. The total aerobic counts differed significantly from values for control animals when the animals were exposed to P. aeruginosa strains BC16, BC17 and BC18. Obligately anaerobic gram-negative rod populations were affected in P. aeruginosa strain BC17-dosed animals. Strains BC16 and BC18 altered both the obligately anaerobic rod populations and total anaerobic counts.
Response of hydrilla (hydrilla ver ticillata(L.f.) royle) to diquat and a model of uptake under nonequilibrium conditions
Authors: Cassidy Kelly , Rodgers John H.
Published: March 2010

Response of the aquatic macrophyte hydrilla (Hydrilla verticillata (L.f.) Royle) to the herbicide diquat was measured by dissolved oxygen concentration in the surrounding water, chlorophyll a concentration in plant tissue and membrane permeability of hydrilla cells. Dissolved oxygen concentration was the most rapid and sensitive measure of response, followed by membrane permeability. Chlorophyll a was an inadequate measure of response because of high variability in measurements and slow response time. The lethal concentration of diquat in hydrilla tissue was approximately 600 μg/g dry weight. The uptake of diquat by hydrilla was modeled under nonequilibrium conditions and assuming exponential decay of diquat from the surrounding water. The modeled uptake depended on the rate of decay of diquat from the water column, the rate of uptake of diquat by hydrilla and the rate of depuration of diquat from hydrilla. The observed uptake closely matched the calibrated, predicted uptake.
Effect of dissolved organic matter from Canadian shield lakes on the bioavailability of 1,3,6,8-Tetrachlorodibenzo-p-dioxin to the amphipod Crangonyx laurentianus
Authors: Servos Mark R. , Muir Derek C. G.
Published: March 2010

The effect of dissolved organic matter (DOM) on the apparent solubility and bioavailability of 1,3,6,8-tetrachlorodibenzo-p-dioxin (1,3,6,8-TCDD) was examined in epilimnetic and sediment interstitial waters collected from the Canadian Shield lakes in the Experimental Lakes Area of Northwestern Ontario. DOM enhanced the apparent solubility of 1,3,6,8-TCDD by as much as three times over the reference DOM-free water (DOM <0.24 mg/L). The percentage of 1,3,6,8-TCDD bound to DOM increased as the dissolved organic carbon (DOC) concentration increased. Uptake rate constants of 1,3,6,8-TCDD in Crangonyx laurentianus decreased in the presence of DOM. Only the 1,3,6,8-TCDD that was truly in solution was apparently available for uptake by biota. The quality or site of collection of the DOM was also an important factor. Sediment interstitial waters had a greater affinity for 1,3,6,8-TCDD than did epilimnetic waters, as indicated by the DOC partition coefficients. Although the DOM may enhance the apparent solubility of 1,3,6,8-TCDD, DOM also reduces the amount of 1,3,6,8-TCDD truly free in solution and therefore bioavailable. Solubility enhancement may, however, lead to greater dispersion of 1,3,6,8-TCDD and low-level exposure of biota as the 1,3,6,8-TCDD gradually desorbs from the TCDD-DOM complex.
An in situ river exposure vessel for bioaccumulation studies with juvenile fish
Authors: Jones Peter A. , Sloan Ronald J.
Published: March 2010

A large-volume, easily handled exposure vessel for juvenile fish for use in bioaccumulation studies of water-borne contaminants in larger rivers was designed and tested in the Hudson River in New York. The exposure vessel minimized stress to the fish and allowed representative contaminant accumulation during time-series subsampling and a long-term in situ exposure.
Acclimation-induced changes in toxicity and induction of metallothionein-like proteins in the fathead minnow following sublethal exposure to zinc
Authors: Hobson James F. , Birge Wesley J.
Published: March 2010

Experiments were conducted to determine if a correlation exists between acclimation-induced alterations in Zn toxicity and the concentration of metallothionein-like proteins (MTP) in a cyprinid fish. Populations of subadult fathead minnows, Pimephales promelas, were maintained in dechlorinated tap water and exposed to 0, 0.60 and 1.80 mg Zn/L for 35 d. Groups of animals (120 each) were removed from each acclimation population after 0, 7, 14, 21 and 35 d to conduct 96-h acute tests. Tolerance and resistance were monitored as changes in the 96-h LC50 and LT50 values, respectively. Tolerance increased a significant 28% above control values after 14 d of exposure to 0.60 mg Zn/L, but decreased significantly to 63 and 74% of control values following exposure to 1.80 mg Zn/L for 7 and 14 d (p < 0.05). Acute toxicity values returned to control levels in both treatment groups after 21 d of exposure and remained stable to 35 d. The concentration of MTP was measured in the viscera (i.e., liver, spleen, intestine and pancreas) indirectly as the total Zn-binding capacity in MTP-containing fractions. MTP levels increased after 7, 14 and 21 d and plateaued to 35 d. Metal concentration in the MTP fraction reached a maximum of 31.6 μg Zn/g viscera, and following 28 d of exposure to 1.80 mg Zn/L concentrations declined to control levels after 7 d in diluent water. Whole-body residues of Zn reached steady state after 7 d of exposure to 0.60 mg Zn/L but continued to increase after 35 d of exposure to 1.80 mg Zn/L. Zn-acclimated animals were cross-resistant but not cross-tolerant to acute Cd challenge. There was no correlation of alterations in toxicity with observed changes in MTP concentration. Growth effects were observed at both acclimation exposure levels.
Stimulation of superoxide production by nitrofurantoin, p-nitrobenzoic acid and m-dinitrobenzene in hepatic microsomes of three species of freshwater fish
Authors: Washburn Peter C. , Di Giulio Richard T.
Published: March 2010

The importance of nitroaromatic compounds as aquatic contaminants and the association of superoxide (O−2) mediated toxicity with the mammalian metabolism of a number of these compounds has led our laboratory to conduct an in vitro investigation of nitroaromatic-stimulated production by freshwater fish. Utilizing cytochrome c reduction and cyanide-insensitive oxygen consumption assays for O−2, channel catfish (Ictalurus punctatus), largemouth bass (Micropterus salmoides) and rainbow trout (Salmo gairdneri) hepatic microsomes were exposed to nitrofurantoin (NF), p-nitrobenzoic acid (PNBA) and m-dinitrobenzene (MDNB). NF and PNBA were chosen for study as model nitroaromatic compounds, known to stimulate microsomal O−2 generation in mammals; MDNB was chosen because it frequently contaminates aquatic systems. The results demonstrated that each of the three nitroaromatics is capable of significantly enhancing superoxide dismutase (SOD) inhibitable cytochrome c reduction and oxygen consumption, providing specific evidence of stimulated microsomal production of O−2 by the fish species examined. The results also indicated chemical- and species-specific differences in stimulated O−2 production. In both assay systems, enhancement by NF exceeded that produced by MDNB and, more pronouncedly, PNBA. Furthermore, although similar responses to all nitroaromatics were observed in microsomes isolated from catfish and bass, the assays employing trout microsomes demonstrated the greatest enhancement in NF and MDNB exposures. These findings suggest that the stimulation of O−2 production may be an important mode of action for these common aquatic pollutants that merits further ecotoxicological assessment.
Mutagenic potential of runoff water from soils amended with three hazardous industrial wastes
Authors: Davol P. , Donnelly K. C. , Brown K. W. , Thomas J. C. , Estiri M. , Jones D. H.
Published: March 2010

The bacterial mutagenicity of runoff water from soils contaminated with hazardous industrial waste was monitored for a three-year period using Salmonella typhimurium strain TA98 with and without metabolic activation. The wastes included a wood-preserving waste, a combined American Petroleum Institute (API) separator/slop oil emulsion sludge and a storm-water runoff impoundment waste. The wastes were applied to a Weswood silt loam soil (Fluventic Ustochrept) and a Bastrop clay loam soil (Udic Paleustalf) at a rate of 3.1% (wt./wt.) for the wood-preserving waste and of 4.5% for the two refinery wastes.

The results indicate that the runoff water from each of the waste-amended soils contained mutagenic constituents. The maximum specific activity was 783 net revertants per milligram residue, which was induced by the runoff water collected from the storm-water runoff impoundment-amended Weswood soil 360 d after application and assayed with metabolic activation. This sample also yielded the maximum weighted activity of 6,554 revertants per liter of runoff water. The mutagenic activities of the runoff water from all waste-amended soils displayed significant increases through 360 d after application and, in most cases, significant decreases in the samples collected approximately three years after application. The mutagenic activities of the runoff water from the Weswood soil were consistently greater than the activities of the runoff water from the Bastrop soil. These results indicate that three years or more may be required for the mutagenic activity of runoff water to return to background level, and that different soils will differ in their capacities to retain mutagenic chemicals during rainfall events.
Adaptation to a quaternary ammonium surfactant in aquatic sediment microcosms
Authors: Shimp Robert J.
Published: March 2010

Adaptation by natural microbial communities may be operationally defined as an increase in the biodegradation rate of a chemical as a result of exposure to the material. The comparative adaptation of sediment-associated and water microbial communities to the sorptive cationic surfactant dodecyltrimethylammonium chloride (C12-TMAC) was studied in continuous-flow, settled-sediment microcosms. In microcosms initially exposed to an input concentration of 0.1 mg/L C12-TMAC, biodegradation activity in the water column increased 20-fold after approximately 10 to 15 d. As input concentrations of C12-TMAC entering the microcosm were increased, water column biodegradation activity also increased, even though measured water column concentrations remained relatively constant, due to biodegradation and/or adsorption. When C12-TMAC input was reduced to zero, microbial activity returned to control levels. Sediment biodegradative activity was unaffected by input concentrations of C12-TMAC below 0.5 mg/L. When the input concentration was increased to 10 mg/L, biodegradative activity increased by at least 10-fold. Once adaptation had occurred in the sediments, the process was relatively unaffected by reductions in the concentration of C12-TMAC entering the microcosms. Thus, relative to processes in the water column, the presence of sediments can influence both the onset of adaptation and its persistence.
Evaluation of bioassays for designing sediment cleanup strategies at a wood treatment site
Authors: Athey Leslie A. , Thomas John M. , Miller William E. , Word Jack Q.
Published: March 2010

Standard bioassays were studied to evaluate their value in guiding remedial action decisions at sites contaminated with wood treatment operation wastes. The toxicities of sediment, sediment elutriate and whole water samples collected from a creek adjacent to a wood treatment site in Mississippi were estimated using six bioassays and compared with estimated concentrations of creosote and related materials obtained from the same samples by infrared spectroscopy. Of the bioassays, Daphnia and Microtox were most sensitive to the contaminants from the wood treatment operation. Based on an analysis of these samples, chemical analysis alone is insufficient to guide cleanup decisions, but bioassays alone can provide usable guidance, especially if more than one contaminant is present.
Bioconcentration of polybrominated benzenes and biphenyls and related superhydrophobic chemicals in fish: Role of bioavailability and elimination into the feces
Authors: Gobas Frank A. P. C. , Clark Kathryn E. , Shiu Wan Ying , Mackay Donald
Published: March 2010

Bioconcentration data are reported for a series of superhydrophobic chemicals including polybrominated biphenyls, brominated benzenes, mirex and polychlorinated biphenyls in the guppy (Poecilia reticulata). The observed bioconcentration factors follow a linear relationship with the 1-octanol/water partition coefficient for chemicals with a log Kow of up to 6. For chemicals with higher Kow values, the bioconcentration factors were lower than expected from the linear relationship. This loss of linear correlation is shown to be caused by (a) a low fraction of bioavailable chemical in the water, (b) elimination of chemical into the feces, (c) an insufficient exposure time to achieve equilibrium and (d) fish growth. Procedures are presented by which the magnitudes and relative contributions of these factors to reducing the apparent bioconcentration factor from linearity can be determined.
Lead poisoning and other mortality factors in trumpeter swans
Authors: Blus Lawrence J. , Stroud Richard K. , Reiswig Barry , McEneaney Terry
Published: March 2010

Lead poisoning and other causes of mortality of trumpeter swans were investigated. Necropsies or Pb concentrations in livers were available for 72 trumpeter swans (Cygnus buccinator) found dead in seven western states from 1976 to 1987; data from other published and unpublished sources (1925 to 1987) also are summarized. Ingestion of lead artifacts (shotgun pellets or fishing sinkers) accounted for about 20% of the known mortality of trumpeter swans in the tri-state area of Idaho, Montana and Wyoming, where the population has been declining for several decades. In western Washington, the incidence of lead-induced mortality was higher and accounted for nearly 50% of the known mortalities. Maximum Pb concentrations (wet weight) in the livers of birds found dead and in whole blood from captured swans were 37 and 0.71 μg/g, respectively. Other elements, including Cd, Cu and Zn, were generally not elevated in blood and tissue samples. It is not certain that lead toxicosis is related to the decline of the tri-state swan population. Other causes of mortality in swans include gunshot, disease and traumatic injuries (impact).
Microbial degradation of sparingly soluble organic chemicals: Phthalate esters
Authors: Gibbons Jacqueline A. , Alexander Martin
Published: March 2010

Strains of Mycobacterium and Nocardia isolated because of their ability to use di(2‒ethylhexyl) phthalate (DEHP) as sole carbon source also grew on diethyl, diisooctyl, and butyl benzyl phthalates. As the two bacteria grew on DEHP, they excreted products that increased the solubility of DEHP and diisooctyl, dihexyl, and diisodecyl but not butyl benzyl or di‒n‒butyl phthalates. The solubilizer was produced by Mycobacterium sp. even when grown on a water‒soluble substrate such as acetate. Addition of the solubilizer to culture media enhanced the degradation of DEHP and diisooctyl phthalate by Mycobacterium sp. and Nocardia sp. but not butyl benzyl phthalate. The extent of DEHP degradation by Mycobacterium sp. in media amended with the solubilizer was reduced and the initiation of degradation was delayed if the solubilizer was first treated with protease. The effect of protease was not a result of its toxicity to Mycobacterium or use of the enzyme preparation for growth of the organism. The results thus show that microbial products increase the solubility of certain phthalates and enhance their degradation.
Transport of some chlorinated contaminants by the water, suspended sediments, and bed sediments in the St. Clair and Detroit rivers
Authors: Lau Y. L. , Krishnappan B. G. , Oliver B. G.
Published: March 2010

Measurements of water flow, sediment transport and concentrations of some chlorinated contaminants were used to calculate the transport of contaminants in the St. Clair and Detroit Rivers. The transport was distributed between the water phase, the suspended sediments, and the bed sediments. The chemicals chosen were hexachlorobenzene, octachlorostyrene and polychlorinated biphenyls. From measurements on three transects in the St. Clair River and two transects in the Detroit River, it can be concluded that the suspended sediments can often transport the largest amount of contaminants, especially near sources of industrial discharge. The amount transported in the soluble phase was of the same order of magnitude as that in the particulate phase. The transport by the bed sediments was negligible in the St. Clair River mainly because of a lack of supply of such sediments. The partitioning of several halogenated compounds between the “dissolved” and “suspended sediment” phase is also discussed.
Atrazine tolerance of algae isolated from two agricultural streams
Authors: Hersh Charles M. , Crumpton William G.
Published: March 2010

Based on photosynthesis (oxygen evolution) EC50s determined from short (5 min) assays, green algae (Chlorella sp. and other species of Chlorococcales) isolated at random from an atrazine‒contaminated stream (Big Spring) in midsummer exhibited similar tolerances to atrazine (range of EC50s: 42–125 μg/L) compared to algae isolated at random from a noncontaminated stream (Osage Spring) (range of EC50s: 35–162 μg/L). A laboratory strain of Chlamydomonas reinhardii known to be susceptible to atrazine responded similarly (EC50: 45 μg/L). The EC50s of these algae are similar to those previously reported for laboratory strains. In contrast, an alga (Franceia sp., Chlorococcales) isolated at random during late spring from Big Spring responded similarly to a laboratory strain of Chlamydomonas reinhardii that is resistant to atrazine (Franceia sp. EC50s: 430–774 μg/L, C. reinhardii EC50: 466 μg/L). The EC50 values of these algae are near the high end of the range of EC50s reported for green algae.
Toxicokinetics and toxicodynamics of pyrethroid insecticides in fish
Authors: Bradbury Steven P. , Coats Joel R.
Published: March 2010

The pyrethroid insecticides are extremely toxic to fish, with 96—h LC50 values generally below 10 μg/L and i.p. and i.v. LD50 values below 20 mg/kg. Corresponding LD50 values in mammals and birds are in the range of several hundred to several thousand milligrams per kilogram. This review examines pyrethroid toxicokinetics and toxicodynamics in fish as critical factors associated with species selectivity. Studies with permethrin, cypermethrin and fenvalerate have established that rates of metabolism and elimination in rainbow trout are significantly lower than those reported for birds and mammals. Comparatively low lethal brain pyrethroid concentrations and nonneural aspects of pyrethroid intoxication in fish suggest that variations in toxicodynamics are also crucial in evaluating pyrethroid selectivity.
Toxicity of pyrethroid insecticides to fish
Authors: Haya Katsuji
Published: March 2010

A selected review of the biological, chemical and environmental factors that affect the acute and chronic, lethal and sublethal toxicity of pyrethroid insecticides to fish is presented. Pyrethroid insecticides are extremely toxic to fish; for example, 96—h LC50 values are in the nmol/L range. The symptoms associated with acute lethality suggest that effects on the nervous system, respiratory surfaces and renal ion regulation are associated with the mechanism of lethal action in fish.

Qualitative structure—activity relationships indicate that the structural features required for good insecticidal activity and for lethality to fish are the same. Lethality also varies with biological (species, size) and environmental (temperature, sediment) factors. Some of these effects may be related to bioavailability and rates of pyrethroid biotransformation.

Chronic exposure studies indicate that newly hatched larvae or early juveniles are the life stages most sensitive to pyrethroids. Exposures of fish to sublethal concentrations of pyrethroids have resulted in decreased growth and impaired swimming performance. The effects on bioenergetics and energy metabolism are variable.
Acute, chronic and sublethal effects of synthetic pyrethroids on freshwater zooplankton
Authors: Day Kristin E.
Published: March 2010

A review of the acute, subacute and chronic effects of four synthetic pyrethroids —permethrin, cypermethrin, deltamethrin and fenvalerate —on freshwater zooplankton is presented. Acute toxicities in the laboratory were found to range from 0.12 to 5.0 μg/L for cladocerans and copepods. Lower concentrations of pyrethroids (≤0.01 μg/L) reduced reproduction and rates of filtration of food by daphnids. Similar results were observed in field experiments. Simulation of direct overspray of aquatic ecosystems resulted in subsurface concentrations of pyrethroids greater than the levels known to be toxic in the laboratory (>1 μg/L). At these concentrations, populations of cladocerans were reduced. At concentrations of 0.05 μg/L or greater, rates of filtration by cladocerans were depressed. Indirect effects on communities included increases in populations of rotifers and green algae (Chlorophyta). Higher levels of contamination (>10 μg/L) caused reductions in copepods, rotifers and ostracods. Levels of pyrethroids of 0.01 μg/L or less were found to have no detectable effects on zooplankton in the field.
Mobility and persistence of the herbicides atrazine, metolachlor and terbuthylazine in plainfield sand determined using field lysimeters
Authors: Bowman B. T.
Published: March 2010

Field lysimeters (75 × 15 cm) packed with 18 kg (dry weight) Plainfield sand were used to study the mobility and persistence of commercial formulations of the herbicides atrazine, metolachlor and terbuthylazine under two precipitation regimes: rainfall, and rainfall with supplementary watering. Leachate from the 70-cm soil cores was monitored daily for each herbicide. Pairs of soil cores for each herbicide and each moisture regime were sectioned (7 × 10 cm) after 1, 2, 4, 8, 12 and 21 weeks to obtain both mobility and persistence data. After 21 weeks under rainfall, the maximum movements of atrazine, terbuthylazine and metolachlor were, respectively, 30, 20 and 10 cm, and under supplementary watering, were, respectively, 70, 50 and 40 cm. Only a single trace of atrazine appeared in the effluent of rainfall cores. Both atrazine and terbuthylazine appeared in the effluent following a 50-mm water application on day 2. Atrazine also appeared in the effluent on several occasions after week 12 under supplementary watering.
Determination of octanol/water partition coefficients for hydrophobic organic chemicals with the “slow-stirring” method
Authors: De Bruijn Jack , Busser Frans , Seinen Willem , Hermens Joop
Published: March 2010

Experimental data are presented on octanol/water partition coefficients for 70 hydrophobic organic chemicals that were determined with a “slow-stirring” method. With this method, log Kow values can be obtained relatively easily, with high reproducibility and low standard deviations. For compounds with log Kow values of less than 4.5, the experimental data agree well with literature data based on the classical shake-flask method. For more hydrophobic compounds, deviations occur because of the formation of octanol emulsions in the shake-flask procedure. In general, there is reasonable agreement with literature data obtained by reversed-phase HPLC or the generator-column method, although substantial deviations do occur for some individual compounds, especially the higher-chlorinated ortho-substituted polychlorinated biphenyl (PCB) congeners. For chlorobenzenes, chloroanilines and PCBs, substituent constants (π) are calculated. With these π values, partition coefficients for these compounds can be estimated simply by calculation.
Hydrolysis of chlorostilbene oxide: I. Hydrolysis in homogeneous systems
Authors: Metwally Mohammed El-Sayed , Lee Wolfe N.
Published: March 2010

The hydrolysis kinetics of 4-chlorostilbene oxide (CSO) in buffered distilled water, in natural waters and in sediment-associated water are reported. The disappearance of CSO followed pseudo-first-order kinetics in buffered distilled water over the experimental pH range of 3 to 11. Below pH 5, acid-catalyzed hydrolysis dominates, with a second-order rate constant of 11.3 (±1.0) M−1 min−1. Above pH 5, hydrolysis is independent of pH, with a rate constant of 1.02 (±0.12) × 10−4 min−1 at 25°C. In natural waters, the hydrolysis rate constant of CSO had an average value of 0.59 (±0.12) × 10−4 min−1. In sediment-associated water, the observed rate constant was 1.70 (±0.05) × 10−4 min−1. Sorption of CSO to the humic materials in natural waters and biotic effects in sediment-associated water appropriately explain the differences from sterile buffer solutions. Buffer catalysis was observed, but on the other hand, a negative ionic strength effect was determined. The formation of diastereoisomers of 1-(4-chlorophenyl)-2-phenylethylene glycol as major products at both acidic and neutral pH values suggests that CSO undergoes acid-catalyzed as well as neutral hydrolysis reactions through an A-1 carbonium ion mechanism. The rate constant for hydrolysis of CSO at pH 14 is only 70% faster than the hydrolysis rate constant over the pH range of 5 to 11, which suggests that nucleophilic addition of hydroxide ion is not the main hydrolytic mechanism of CSO hydrolysis at high pH values.
Special applications of insect gut microflora in kinetic studies of microbial substrate removal rates
Authors: Lewis David L. , Said William A.
Published: March 2010

Because of the highly controlled environment in which they live and their unique genetic history, the gut microflora of some insects may be useful for studying some of the underlying principles that govern the kinetics of uptake and metabolism of substrates by microorganisms. In the present studies, D-glucose mineralization kinetics were investigated using facultative anaerobes from termite gut microflora to test the similarity of kinetics principles developed previously with aquatic environmental microbial samples. As with environmental samples, heterogeneous kinetics were observed in the gut microflora, with increasingly enhanced glucose removal rates at diminishing amended substrate concentrations. These results lend support to the general applicability of these kinetics principles to a diversity of mixed microbial populations having greatly dissimilar environmental histories.
Toxicity and biodegradation of phthalic acid esters under methanogenic conditions
Authors: O'Connor Owen A. , Rivera M. D. , Young L. Y.
Published: March 2010

Phthalate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate and di(2-ethylhexyl) phthalate were evaluated for their anaerobic biodegradability and toxicity to methanogenesis. Two anaerobic bioassays (the biochemical methane potential and the anaerobic toxicity assay) were used to monitor the stoichiometric conversion of added substrate to carbon dioxide and methane. Each phthalic acid ester was the only added carbon source (20 to 200 mg/L) prepared in prereduced defined medium using a 10% (v/v) inoculum of municipal digester sludge. Over an extended incubation period (50 to 100 d), all concentrations of phthalate and dibutyl phthalate and low concentrations (20 mg/L) of dimethyl phthalate and diethyl phthalate achieved 75 to 100% of their theoretical methane potentials. Higher concentrations (100 to 200 mg/L) of dimethyl phthalate and diethyl phthalate achieved 25 to 50% of their theoretical methane potentials. Di(2-ethylhexyl) phthalate showed little mineralization at any concentration, although biotransformation of this substrate was indicated. Acclimation for most of the compounds took several days to weeks before degradation commenced. In the anaerobic toxicity assay, only concentrations greater than 20 mg/L diethyl phthalate produced any significant suppression of methanogenesis over time. All other substrates produced little inhibition of methanogenesis during the initial period of incubation. Generally, increased incubation led to increased levels of methane production above active control levels. Thus, many of these compounds were metabolized completely under methanogenic conditions and were observed to produce little inhibition of methane production. Their fate, therefore, may be significantly influenced by their concentration and residence time in methanogenic habitats.
Airborne residues resulting from use of methyl parathion, molinate and thiobencarb on rice in the sacramento valley, California
Authors: Seiber James N. , McChesney Michael M. , Woodrow James E.
Published: March 2010

In connection with requirements of California's Toxic Air Contaminant Act, 24-h ambient air samples were collected using an XAD-4 resin trap technique capable of simultaneously collecting methyl parathion, methyl paraoxon, molinate and thiobencarb. Sampling was conducted on rooftops of public buildings located in four towns in two counties where methyl parathion, molinate and thiobencarb were used in significant quantities, and at a background site located in a county where no use occurred, for four intervals each week for 5 weeks during the springtime application period of 1986. Satisfactory recoveries (greater than 66%) were obtained from dynamic spiking experiments, and the precision from field replicates was consistently less than 50% relative standard deviation using a protocol designed to accommodate a large number of samples. Daily maximum average concentrations (and the range in averages for all sites over the 19 and 20 sampling days in the two-county use area) were 25.7 ng/m3 (0.2-6.2 ng/m3) for methyl parathion, 3.1 ng/m3 (<0.5-0.8 ng/m3) for methyl paraoxon, 1,720 ng/m3 (60-650 ng/m3) for molinate and 250 ng/m3 (12.9-67.8 ng/m3) for thiobencarb. Concentrations correlated well with reported uses of methyl parathion and molinate in the general vicinity of the sampling sites. The likely sources of observed residue levels, based upon the method of application and pesticide physicochemical properties, were spray drift during application for methyl parathion, vapor-phase oxidation of parent thion for methyl paraoxon, and postapplication volatilization from field water for molinate and thiobencarb.
Current approaches to developing sediment quality criteria
Authors: Chapman Peter M.
Published: March 2010

Current approaches to developing sediment quality criteria are reviewed and separated into two major groups: those approaches that provide only chemical-by-chemical criteria and those that provide criteria for chemical mixtures also. The individual approaches include background sediment chemistry, water quality criteria, sediment/water equilibrium partitioning, sediment bioas-say, screening level concentration, apparent effects threshold and sediment quality triad. Based on the evaluation of the two groups and seven individual approaches, it is concluded that, for chemical-by-chemical criteria, the equilibrium partitioning method shows promise; for criteria that are also applicable to chemical mixtures, the apparent effects threshold/sediment quality triad approaches appear to be most appropriate. Recommendations are made concerning specific immediate research needs, related to developing effective, usable sediment quality criteria.
Survival, reproduction and bioconcentration in invertebrates and fish exposed to hexachlorobenzene
Authors: Nebeker Alan V. , Griffis William L. , Wise Claudia M. , Hopkins Elmina , Barbitta Janet A.
Published: March 2010

The cladoceran Daphnia magna, the amphipods Hyalella azteca and Gammarus lacustris, the annelid worm Lumbriculus variegatus and the fathead minnow Pimephales promelas were exposed to hexachlorobenzene (HCB) in flow-through tests ranging from 2 to 68 d in duration to determine the effects of HCB on survival, tissue bioconcentration and Hyalella and Lumbriculus growth and reproduction.

No effects on survival, growth or reproduction were observed at concentrations of HCB up to saturation (5.0 μ/L) or at tissue HCB concentrations of up to 223 μg/g. Tissue HCB concentrations increased with increasing water concentrations, and tissue bioconcentration values were generally similar. Rapid uptake and change of tissue HCB concentration with change in water concentration occurred, with rapid depuration when the animals were no longer exposed to HCB in the water column, and tissue HCB concentrations were correlated closely with HCB water concentrations.
Allozyme genotype and time to death of mosquitofish, Gambusia affinis (baird and girard), during acute exposure to inorganic mercury
Authors: Diamond Stephen A. , Newman Michael C. , Mulvey Margaret , Dixon Philip M. , Martinson Douglas
Published: March 2010

Genetic plasticity in a mosquitofish (Gambusia affinis Baird and Girard) population was examined relative to acute mercury toxicity. Genotypes at eight loci (isocitrate dehydrogenase-1 and -2, mannosephosphate isomerase, glucosephosphate isomerase-2, fumarate hydratase, malate dehydrogenase-1, leucylglycylglycine peptidase and phenylalanylproline peptidase) were scored using starch gel electrophoresis. Two null hypotheses were tested: (a) time to death does not differ between genotypes at individual loci and (b) time to death does not differ with multiple-locus heterozygosity. Genotypes at three of the eight loci displayed significant effects on mosquitofish time to death. Multiple-locus heterozygosity also had a significant effect on time to death. Significant amounts of genetic plasticity were found in a population of mosquitofish with no previous exposure to inorganic mercury.
Insects as indicators of toxicity, bioaccumulation and bioavailability of environmental contaminants
Authors: Walton Barbara T.
Published: March 2010

The early involvement of entomologists in ecotoxicology is recognized in this article in celebration of the 70th birthday of Professor Robert L. Metcalf, who was among the first biologists to examine the potential for pesticides to produce unwanted environmental effects. The high sensitivity of insects to some toxicants and the potential insects have for biologically monitoring environmental contaminants is illustrated through review of developmental effects induced with benz[g]isoquinoline-5,10-dione (biquidone) and other chemicals in the cricket Acheta domesticus (L.). A teratogen-sensitive period of development is demonstrated prior to germ band formation in embryos of A. domesticus and of the field cricket Gryllus rubens (Scudder). An active mixed function oxidase system is shown for the embryos of both species through metabolism of [3H]benzo[a]pyrene to 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene. Additional studies are cited to show that careful consideration of insect responses to toxicants can lead to the development of sensitive, cost-effective assays and monitoring approaches to assess the probable effects of chemical contamination in the environment.
Methods for growth inhibition toxicity tests with freshwater algae
Authors: Nyholm Niels , Källqvist Torsten
Published: March 2010

A critical review of batch-culture freshwater algal toxicity test methods (algal growth inhibition tests) is presented. Interlaboratory comparisons have revealed that the results from such tests can vary a great deal, in some cases by more than three orders of magnitude. The potential causes of variability are the physical/chemical experimental parameters. Algal tests, however, need not be very strictly standardized in order to be reproducible if tests are appropriately conducted and the experimental parameters are understood and controlled. Many algal toxicity data reported in the literature seem to have been generated from tests performed with an excessively high biomass and under poor gas-exchange conditions, the combination of which will cause an insufficient supply of carbon dioxide leading to high pH levels and sometimes even to mass-transport (carbon dioxide)-limited linear growth. Poor gas-exchange conditions will prevail unless the test flasks are shaken or aerated continuously. Literature data on the toxicity of chemicals to algae should therefore be used only with careful evaluation of the test method involved.
Photolysis of picloram in dilute aqueous solution
Authors: Woodburn Kent B. , Fontaine Donald D. , Bjerke E. Lee , Kallos George J.
Published: March 2010

The photolysis of [2,6-14C]pyridine-labeled picloram (4-amino-3,5,6-trichloro-2-pyridine carboxylic acid) was studied at 25°C in sterile, buffered water at pH 7 and in a natural water sample taken from a forest ecosystem. The first-order half-life for picloram photodegradation was the same in both systems, averaging 2.6 d at 25°C for a 40°N latitude location, midsummer time frame. The photolytic decay of picloram in solution produced two major photoproducts. Thermospray liquid chromatography-mass spectrometry (TSP/LC/MS) and gas chromatography/mass spectrometry (GC/MS) in the electron impact and chemical ionization mode were used to elucidate the structures of the photolysis products. The two major 14C-labeled photoproducts were conclusively identified through comparison with analytical standards as oxamic acid (C2H3O4N) and 3-oxo-β-alanine (C3H5O4N).
Relation of hepatic microsomal monooxygenase activity to tissue PCBs in rainbow trout (salmo gairdneri) injected with [14C] PCBs
Authors: Melancon Mark J. , Turnquist Karen A. , Lech John J.
Published: March 2010

The relationship of tissue PCB levels to hepatic microsomal monooxygenase activity in rainbow trout (Salmo gairdneri) was assessed. This was accomplished by injecting individual trout with corn oil vehicle or with a [14C]PCB mixture in corn oil. At 3 to 70 d after injection, tissue [14C]PCB concentrations were determined by scintillation counting of solubilized tissue samples, and hepatic microsomes were prepared and assayed for ethoxyresorufin-O-deethylase and ethoxy-coumarin-O-deethylase activities. At three days after injection only the highest doses of PCBs caused elevation of hepatic microsomal monooxygenase activity. At later times, muscle and liver concentrations of PCBs at or lower than 250 ng/g were associated with hepatic microsomal monooxygenase activity at or near control levels. Elevated hepatic microsomal monooxygenase activity was associated with muscle and liver PCB concentrations 300 ng/g or higher, but not all fish with tissue PCBs above this concentration had elevated hepatic microsomal monooxygenase activity.
Effect of metolachlor on azotobacter nitrogen fixation in soil
Authors: Martinez-Toledo Maria V. , Gonzalez-Lopez J.
Published: March 2010

The effect on nitrogen fixation of 100, 200, 300, 400 and 500 μg metolachlor per gram of soil was studied in nonsterile soil incubated under aerobic conditions and sterilized soil inoculated with Azotobacter chroococcum. Metolachlor at concentrations of 400 and 500 μg/g significantly reduced dinitrogen fixation in nonsterile soil and sterile soil inoculated with Azotobacter sp. However, this inhibitory effect on nitrogenase activity disappeared after 24 h, showing that acrobic diazotrophs populations present in the soil can tolerate high concentration of this herbicide without significant changes in their nitrogenase activity.
Reduced growth and motility of euglena gracilis in the presence of aflatoxin B1 and trichothecene T-2 toxin
Authors: Weekley L. Bruce , O'Rear Charles E. , Kimbrough T. Daniel , Llewellyn Gerald C.
Published: March 2010

The ciliated protozoan, Euglena gracilis, was cultured in the presence of aflatoxin B1 (AFB1) (10, 100, and 1000 ng/ml) or T-2 toxin (10, 100 and 1000 ng/ml) for 6 d. During this period, the control culture size progressively increased, while both AFB1 and T-2 toxin reduced culture size in a dose-dependent manner. The sensitivity of the changes in Euglena gracilis growth rate to AFB1 suggests that this organism may have only limited application as a bioassay. Protozoal motility (as assessed by changes in turbidity) was reduced by both toxins, but not in a dose-dependent manner.
Bioassay of acute toxicity of herbicide mixture dalapon/weedazol 4L on estuarine fauna
Authors: Gillespie Paul A.
Published: March 2010

The acute toxicities of dilutions of a herbicide spray formulation suggested for use in salt-marsh environments to eradicate Spartina sp. have been estimated for six estuarine animal species using two complementary laboratory bioassay procedures. Responses of the test species ranged from highly sensitive for the whitebait (Galaxias maculatus) (2-h LC50 of 0.45% corresponding to active ingredient concentrations of 36, 26 and 6 mg/L for dalapon, amitrole and NH4CNS, respectively) to extremely resistant for the mud crab (Helice crassa) (no mortality during a 4-h exposure after direct spraying with the full-strength mixture). Intermediate levels of toxicity were observed for the cockle (Chione stutchburyi), the mud snails (Amphibola crenata and Potamopyrgus estuarinus) and the estuarine prawn (Palaemon affinis). The results suggest that acute (lethal) effects on estuarine fauna would in most cases be minimal during actual spraying except where animals or shallow-pooled areas covering animals are sprayed directly.
Impact of an episodic event on the toxicity evaluation of a treated municipal effluent
Authors: Lewis M. A. , Eckhoff W. S. , Cooney J. D.
Published: March 2010

The chronic toxicities of a treated municipal effluent and the corresponding receiving water were evaluated for fathead minnows and Ceriodaphnia dubia in standard 7-d toxicity tests. The effluent and river water were not significantly toxic to the fathead minnow based on measurements for survival and weight. Ceriodaphnia survival after 3 d exposure in the controls and five test concentrations ranged from 60 to 100%, but on test day 4, survival was significantly reduced at all test levels including in the controls. The toxicity was attributable to the dilution water, which was river water collected above the WWTP outfall. The toxicant(s) in the dilution water was not identified based on a comparison of the daily chemical analyses. Overall, the utilization of the receiving water for dilution water in the toxicity tests showed the potential of an episodic event to control the quality of biota in the receiving water.
Terrestrial population models for ecological risk assessment: A state-of-the-art review
Authors: Emlen John M.
Published: March 2010

Few attempts have been made to formulate models for predicting impacts of xenobiotic chemicals on wildlife populations. However, considerable effort has been invested in wildlife optimal exploitation models. Because death from intoxication has a similar effect on population dynamics as death by harvesting, these management models are applicable to ecological risk assessment. An underlying Leslie-matrix bookkeeping formulation is widely applicable to vertebrate wildlife populations. Unfortunately, however, the various submodels that track birth, death, and dispersal rates as functions of the physical, chemical, and biotic environment are by their nature almost inevitably highly species- and locale-specific. Short-term prediction of one-time chemical applications requires only information on mortality before and after contamination. In such cases a simple matrix formulation may be adequate for risk assessment. But generally, risk must be projected over periods of a generation or more. This precludes generic protocols for risk assessment and also the ready and inexpensive predictions of a chemical's influence on a given population. When designing and applying models for ecological risk assessment at the population level, the endpoints (output) of concern must be carefully and rigorously defined. The most easily accessible and appropriate endpoints are (1) pseudoextinction (the frequency or probability of a population falling below a prespecified density), and (2) temporal mean population density. Spatial and temporal extent of predicted changes must be clearly specified a priori to avoid apparent contradictions and confusion.