bluuebunny/crossref_metadata_2025 huggingface dataset:
Sorption of nonpolar organic chemicals on low-carbon-content aquifer materials
Authors: Stauffer Thomas B. , Wickman Donald C. , Macintyre William G.
Published: March 2010

Sorption isotherms were measured by batch equilibration methods for three nonpolar organic sorbates on seven subsurface, low-carbon sedimentary aquifer materials. Radiolabeled (14C) 1-methylnaphthalene, o-dichlorobenzene and naphthalene were separately equilibrated with the sorbents to determine sorption coefficients (K). Chemical and physical properties of the aquifer materials were determined.

Possible relationships between sorption coefficients and organic carbon (OC) content and other sorbent properties were investigated using multivariate statistics. Sorbent properties used in the statistical analysis were sorption coefficients, percentage OC, percentage sand, percentage clay, percentage silt, specific surface area, cation exchange capacity, percentage 1:1 clay, percentage 2:1 clay and percentage iron content. No predictive relationships between sorption coefficients and aquifer material properties were found. The sorption coefficient does not correlate with any of the properties of the aquifer materials, including OC content for aquifer materials with OC content of less than 0.10%. It is recommended that sorption coefficients be determined experimentally on each different aquifer material for use in ground water transport calculations.
Toxicity and anaerobic biodegradability of substituted phenols under methanogenic conditions
Authors: O'Connor Owen A. , Young L. Y.
Published: March 2010

Phenol, 2-chlorophenol, 2,4-dimethylphenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 3-methyl-4-chlorophenol (4-chloro-m-cresol) and 2-methyl-4,6-dinitrophenol (4,6-dinitro-o-cresol) were evaluated for their anaerobic biodegradability and toxicity to methanogenesis using two anaerobic bioassays, the biochemical methane potential (BMP) and the anaerobic toxicity assay (ATA). The BMP and ATA were used to evaluate the stoichiometric conversion of added substrate carbon to CO2 and CH4. Each substrate was the only added carbon source (20-200 mg/L) prepared in prereduced defined medium using a 10% (v/v) inoculum of municipal digester sludge. All concentrations of phenol and low concentrations (20 mg/L) of 2-chlorophenol, 2-nitrophenol, 4-nitrophenol and 2,4-dinitrophenol were completely mineralized. Higher concentrations of these same substrates (100 mg/L) and all concentrations of dimethylphenol, 3-methyl-4-chlorophenol and 2-methyl-4,6-dinitrophenol were observed to undergo no significant mineralization of added substrate and inhibited methanogenesis to varying degrees. Significant biotransformation of the monosubstituted nitrophenols occurred, resulting in the production of the corresponding aminophenols. Acclimation for most compounds took several days to weeks before methane could be detected in the substrate-amended cultures. Generally, the greater the substitution of the phenolic ring, the greater were the recalcitrance and toxicity of the substrate. The fate of these compounds can be significantly influenced by both their concentration and their residence time in anoxic environments.
Thermal modulation of benzo[a]pyrene uptake in the gulf toadfish, Opsanus beta
Authors: Kennedy Christopher J. , Gill Kenneth A. , Walsh Patrick J.
Published: March 2010

Gulf toadfish, Opsanus beta, were exposed to initial [14C]benzo[a]pyrene (BaP) concentrations of 5μg/L in a simple static system at high and low temperatures (18 or 28°C) following long-term (>4 weeks) acclimation to these temperatures or an acute temperature change (18 to 28°C or 28 to 18°C) to assess the effects of temperature on the uptake and disposition of BaP. BaP uptake was estimated from the disappearance of BaP from the water. Uptake rates estimated at initial BaP concentrations for the four temperature treatments (acclimation temperature: exposure temperature), 28:18, 28:28, 18:18 and 18:28°C, were 0.020 ± 0.001, 0.051 ± 0.005, 0.031 ± 0.004 and 0.065 ± 0.004 μg BaP/g body weight/h (±se, N = 6). The decrease in BaP uptake with decreasing BaP concentration indicates that BaP uptake is directly proportional to the concentration in water, and calculated Q10 values suggest that uptake is modulated by temperature-induced changes in respiration rate or convection volume. BaP was detected in all tissues examined, with the highest levels in the bile, the liver, the kidney and the gills. Greater uptake rates of carcinogens such as BaP at higher temperatures may in part explain higher rates of tumor formation in fish exposed to carcinogens at high temperatures.
Effects of freezing on toxicity of sediments contaminated with ddt and endrin
Authors: Schuytema Gerald S. , Nebeker Alan V. , Griffis William L. , Miller Clifford E.
Published: March 2010

Two freshwater sediments containing 3 and 11% total organic carbon (TOC) were spiked with DDT and endrin to compare the effects of cold (4°C) and frozen (−20°C) storage of the sediment on toxicity to the amphipod Hyalella azteca in 10-d tests. Toxicity of the DDT-spiked sediment was reduced when it was frozen for 14 d. LC50 values for cold-stored and frozen-stored sediments were 4.2 and 7.3 μg/g DDT (calculated on dry solids basis) at 3% sediment TOC and 11.1 and 23.2 μg/g DDT at 11% sediment TOC, respectively. Toxicity of the 3% TOC endrin-spiked sediment was reduced by freezing; it exhibited LC50s of 5.1 and 7.7 μg/g endrin, respectively, for cold and frozen storage. Toxicity of endrin in two tests in the 11% TOC sediment remained essentially unchanged by freezing. LC50s were 19.6 and 21.7 μg/g endrin for cold and frozen sediments in one test and 10.3 and 9.8 μg/g endrin in the second test. Decreased toxicity was assumed to be related to the release of soluble organic carbon from the sediments during freezing and thawing. Relative differences in toxicity between DDT and endrin for cold and frozen sediments appear to be related to the different adsorptions of the chemicals onto the released carbon.
Effects of kelthane® on reproduction of captive eastern screech-owls
Authors: Wiemeyer Stanley N. , Spann James W. , Bunck Christine M. , Krynitsky Alexander J.
Published: March 2010

Eastern screech-owls (Otus asio) were fed diets containing 10 ppm Kelthane® with 3.4% DDT-related contaminants (old technical formulation), 10 ppm Kelthane with no detectable DDT contaminants (new technical formulation) or a control diet. Food consumption, adult weight and date of initiation of egg laying were similar for birds in control and dosed treatment groups. Most measures of reproductive success were similar for control and dosed treatment groups. Shell weight and thickness index were significantly lower for both dosed groups than for controls. Shell thickness was significantly lower for the new Kelthane treatment than for controls. Concentrations of p,p'-DDE were significantly higher in eggs laid by pairs receiving old Kelthane than in those of birds receiving new Kelthane or in controls. Concentrations of dichlorobenzophenone, dicofol and dechlorodicofols were significantly higher in carcasses of dosed owls than in controls, whereas concentrations of DDE were significantly higher in carcasses of owls fed old Kelthane than in controls or owls fed new Kelthane.
Time-toxicity relationships in fish exposed to the organochlorine pesticide methoxychlor
Authors: Heming Thomas A. , Sharma Arvind , Kumar Yogesh
Published: March 2010

Time-toxicity relationships for methoxychlor were developed for five species and two stocks of fish (lake whitefish, Coregonus clupeaformis; spottail shiner, Notropis hudsonius; walleye, Stizostedion vitreum vitreum; white sucker, Catostomus commersoni; and two stocks of rainbow trout, Salmo gairdneri). Four different pulse regimes were tested, namely, a 2-h methoxychlor exposure followed by 94 h in fresh water, a 6-h exposure followed by 90 h in fresh water, a 24-h exposure followed by 72 h in fresh water, and a 96-h exposure. Time-toxicity relationships for methoxychlor varied inter- and intraspecifically. Intraspecies effects were probably size related; the 96-h median lethal concentration (LC50) for rainbow trout was 9.36 μg/L (95% C.L. 5.71, 15.3) for stock A fish (average size 1.2 g) and 31.2 μg/L (95% C.L. 24.7, 39.6) for stock B fish (average size 6.7 g). Methoxychlor exhibited a delayed toxic effect, the relative magnitude of which was a function of exposure duration and concentration, and fish species. Of the fish species examined, walleye was the most sensitive to short-term pulses (<24 h) of methoxychlor. Walleye had a relatively low 96-h LC50 (19.2 μg/L; 95% C.L. 9.00, 41.1), experienced the greatest delayed toxic effects and, in terms of median survival time (tm), was most sensitive to changes in methoxychlor concentration. Rainbow trout appeared to be the species most sensitive to chronic methoxychlor exposure; its asymptotic LC50 (stock A 4.05 ± 2.84 μg/L, stock B 5.14 ± 3.14 μg/L) was significantly lower than those of other species. White sucker was the species least sensitive to acute exposure. White suckers experienced no delayed toxic effects and had the highest 96-h (114 μg/L; 95% C.L. 87.7, 150) and asymptotic LC50 (205 ± 85 μg/L) values.
Chronic effects of the photoenhanced toxicity of anthracene on Daphnia magna reproduction
Authors: Holst Linda L. , Giesy John P.
Published: March 2010

The chronic effects of exposure to anthracene and ultraviolet radiation (UVR) on Daphnia magna reproduction were investigated. D. magna were exposed to anthracene in the presence or absence of ecologically relevant intensities of UVR for 21 d. Exposure to 8.2 μg/L anthracene in the absence of UVR significantly reduced the number of neonates produced by 13.8%; however, exposure to UVR in the absence of anthracene had no significant effect on the fecundity of D. magna. Concurrent exposure of D. magna to UVR and anthracene resulted in further reduced survival and fecundity. Exposure of D. magna to 7.2 μg/L anthracene and 117 μW/cm2 UV-A radiation resulted in 70% mortality or a 69% decrease in production of neonates by D. magna that survived. The reduction in fecundity was proportional to both anthracene concentration and UVR intensity. Equations were developed that predict the relative percent reduction in production of neonates due to the photoenhanced toxicity of anthracene given a particular anthracene concentration and UVR intensity.
Dynamics of organochlorine compounds in herring gulls: III. Tissue distribution and bioaccumulation in lake ontario gulls
Authors: Braune Birgit M. , Norstrom Ross J.
Published: March 2010

Apparent biomagnification factors (BMFs, wet weight basis) for organochlorine compounds in herring gulls (Larus argentatus) in Lake Ontario were shown to be related to chlorine substitution patterns in the case of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). PCBs accumulated according to the availability of adjacent positions not substituted with chlorine: (a) para-meta unsubstituted (P group), mean BMF 20 ± 6.2; (b) meta-ortho unsubstituted (M group), mean BMF 87 ± 36; and (c) no adjacent unsubstituted positions (blocked, B group), mean BMF 154 ± 39. Among the other organochlorines, DDT, cis- and trans-nonachlor, dieldrin and octachlorostyrene magnified to the least extent (BMF 3-19), and photomirex, mirex and DDE magnified to the greatest extent (BMF 85-100). Of the PCDDs and PCDFs, 2,3,7,8-TCDD and 2,3,4,7,8-PnCDF biomagnified to a greater degree than did other congeners (BMF 32 and 7, respectively). There were no significant differences among egg-to-whole-body ratios (mean 0.60 ± 0.11, lipid weight basis) for any of the organochlorines except PCDDs and PCDFs, indicating that partitioning among lipid pools in the body is the main determining factor in tissue distribution. Egg-to-whole-body ratios for PCDDs (mean 1.2 ± 0.33) and PCDFs (mean 0.87 ± 0.02) were higher than but not significantly different from those for other organochlorines. Liver-to-whole-body ratios (mean 0.80 ± 0.16) also did not differ significantly among organochlorines, except that heptachlor epoxide, dieldrin, PCDDs and PCDFs had higher ratios. The mean fraction of the total body burden of PCDDs and PCDFs contained in the liver ranged from 5 to 55%, compared with 1 to 5% among the other organochlorines, and it increased with degree of chlorination.
Findings of tributyltin, dibutyltin and monobutyltin in bivalves from selected U.S. coastal waters
Authors: Uhler Allen D. , Coogan Theodore H. , Davis Kenneth S. , Durell Gregory S. , Steinhauer William G. , Freitas Sandra Y. , Boehm Paul D.
Published: March 2010

A method is presented for determining trace levels of tributyltin (TBT) and its degradation products dibutyltin (DBT) and monobutyltin (MBT) and the TBT manufacturing impurity tetrabutyltin (TTBT) in bivalve mollusc tissue. Butyltin compounds were analyzed in bivalve molluscs collected from selected near-shore sites of the U.S. east and west coasts. All bivalves from the sites investigated were contaminated with TBT, DBT and, sporadically, MBT. The ratio of TBT/DBT in sentinel organism tissue appears to be a species-specific equilibrium value, with average values for Mytilus edulis of 2.5 and Mytilus californianus of 11.6.
Polychlorinated dibenzofurans and polychlorinated dibenzo-p-dioxins in great lakes fish: A baseline and interlake comparison
Authors: De Vault David , Dunn William , Bergqvist Per-Anders , Wiberg Karin , Rappe Christoffer
Published: March 2010

Fish from each of the Great Lakes and Lake St. Clair were analyzed for 10 congeners of polychlorinated dibenzofurans (PCDFs) and 8 congeners of polychlorinated dibenzo-p-dioxins (PCDDs). PCDFs and PCDDs were identified above detection limits in samples from each lake. Concentrations of PCDFs, principally 2,3,7,8-TCDF, were highest (102.4 ng/kg) in Lake Michigan lake trout and lowest in late trout from Lake Superior (20.9 ng/kg). Total PCDD concentrations ranged from 7.2 ng/kg in Lake Superior lake trout in 64.5 ng/kg in Lake Ontario lake trout. Concentrations of 2,3,7,8-TCDD ranged from 1.0 ng/kg in Lake Superior lake trout to 48.9 ng/kg in lake trout from Lake Ontario.

While the upper lakes were somewhat similar in the absolute concentration and composition of PCDFs and PCDDs, principle components analysis identified statistically significant inter- and in-tralake differences in the composition of total PCDF and total PCDD. These differences suggest differences in the sources of these compounds to each of the Great Lakes.
Glutathione-dependent metabolism in fish and rodents
Authors: Wallace Kendall B.
Published: March 2010

Hepatic glutathione (GSH) concentration was significantly higher in rats and mice compared to either fathead minnows or rainbow trout. In rodents, the concentration of GSH approximated the Km of hepatic glutathione peroxidase (GPx), whereas in fish GSH concentration was less than the Km of GPx. The significantly lower Km for oxidized glutathione (GSSG) of glutathione reductase compared to the Km for GSH of the peroxidase is consistent with the large ratio of reduced-to-oxidized glutathione in all four species. The concentration of GSH in rodent liver far exceeds the Km for hepatic glutathione-S-transferase (GST), which contrasts with that observed for fish. Furthermore, the greater activity of renal gamma-glutamyl transpeptidase in rodents compared to fish suggests that, once formed, glutathione conjugates are rapidly hydrolyzed, leading to greater mer-capturic acid production in rats and mice. Collectively, these data suggest that rodents are quite capable of conducting GSH-dependent detoxification of prooxidants and electrophiles, whereas in fish GSH-dependent metabolism appears to be self-limited by the availability of endogenous GSH. Accordingly, the data suggest that fish may be disproportionately more susceptible than rodents to xenobiotics that are eliminated principally by GSH-dependent metabolic detoxification.
A multitrophic level evaluation of sediment toxicity in waukegan and indiana harbors
Authors: Allen Burton G. , Stemmer Betty L. , Winks Kelly L. , Ross Philippe E. , Burnett Louann C.
Published: March 2010

The toxicity of sediments from three Waukegan Harbor sites, two Indiana Harbor sites and one reference site (Homer Lake) were evaluated using a multitrophic level test battery. The test battery consisted of the following assays: Daphnia magna 48-h survival, Ceriodaphnia dubia 48-h survival, Hyalella azteca 48-h survival, Selenastrum capricornutum 48-h growth inhibition and enzymatic activity of the indigenous microbial community (alkaline phosphatase, electron transport system activity, ß-galactosidase and ß-glucosidase). All assays, with the exception of S. capricornutum, were conducted using both whole sediments and elutriate (water-extractable) fractions. The test battery effectively discriminated between sites in most cases. However, response patterns varied slightly between macrofaunal and microbial responses and between whole sediment and elutriate phase responses. C. dubia was the most sensitive and H. azteca the least sensitive macrofaunal test species. Microbial community assays showed a greater range of responses, thus providing for greater discrimination between test sites. ß-galactosidase and ß-glucosidase were the most sensitive microbial assays. The acute toxicity response patterns verified sites containing the highest levels of contaminants at Waukegan Harbor and detected contamination in Indiana Harbor. Differences between degree and/or pattern of response and whole sediment versus elutriate toxicity patterns demonstrated both the usefulness and necessity of a multitrophic level toxicity test battery in sediment quality assessments.
Biochemical responses in aquatic animals: A review of determinants of oxidative stress
Authors: Di Giulio Richard T. , Washburn Peter C. , Wenning Richard J. , Winston Gary W. , Jewell Catherine S.
Published: March 2010

The study of biochemical responses in aquatic animals comprises a vigorous area of inquiry within ecotoxicology for a number of reasons, including the perceived need for basic research in the field, the desire for highly sensitive biomarkers useful for biomonitoring and the particular concern for elevated rates of neoplasia observed in some aquatic systems. In this paper, an approach only recently investigated by aquatic toxicologists will be described and reviewed in detail. This approach is based on theories of oxyradical generation and subsequent oxidative stress in biological systems. Of particular concern to environmental toxicologists with respect to these phenomena are the abilities of a number of common and diverse compounds to undergo enzymatically facilitated redox cycling in cells and thereby generate oxyradicals under aerobic conditions. Mechanisms of oxyradical generation, toxicological consequences of these processes and endogenous antioxidant defense systems are described. In addition, methodologies for studying these phenomena are discussed and recent studies demonstrating their applicability to aquatic toxicology are reviewed.
Reactions of selected nucleophiles with 2-chloropropenal, a mutagenic constituent of softwood kraft chlorination effluent
Authors: Tachibana Sanro , Santodonato Joseph , Dence Carlton W.
Published: March 2010

2-Chloropropenal (2-chloroacrolein), a constituent of softwood kraft chlorination effluent that gives strongly positive results in the Salmonella mutagenicity assay (Ames Test), was reacted with various nucleophiles and the resulting effect on mutagenicity monitored. Nucleophiles such as hydroxide ion and sulfur dioxide (HSO−3, SO3) proved very effective in reducing the mutagenicity of aqueous 2-chloropropenal solutions. The application of other strong nucleophiles, (glutathione, pyrrolidine and sodium thiosulfate) to 2-chloropropenal also produced substantial benefits in terms of mutagenicity reduction. Further experimentation revealed that the loss of mutagenicity was not the result of the removal of organically bound chlorine but rather the removal of the ethylenic group in 2-chloropropenal, possibly as a consequence of undergoing Michael-type 1,4-addition reactions with the various nucleophiles. In the treatment of 2-chloropropenal with alkali (pH 9), additional condensation of the acrolein derivative to a polymer was demonstrated by gel permeation chromatography.
Biochemical analysis of allozyme copper and cadmium tolerance in fish using starch gel electrophoresis
Authors: Chagnon Norman L. , Guttman Sheldon I.
Published: March 2010

The in vitro effects of copper and cadmium on fish enzyme activity were assayed by combining the metals with the biochemical stains used to resolve these enzyme systems on starch gels. The effects of copper and cadmium on the activity of PGM-2, GPI-2 and IDH-2 enzymes in mosquitofish were assayed using stain-metal mixtures containing 2.0 ml 0.1 m CuSO4 · 5H2O or 0.1 m CdSO4. Enzymes whose activities were effected by copper in this initial test were resolved using a series of stain-metal mixtures containing copper at lower concentrations to determine effect threshold concentration ranges and to determine concentration ranges that might produce differential effects on activity among allozymes of a single protein. Interspecific differences in the effect of copper on the activity of PGM-2 enzyme variants were examined for 17 fish species from seven locations.

Copper was found to effect the activity of PGM-2, GPI-2, and IDH-2 enzymes in mosquitofish and intraspecific and interspecific differences existed in the copper sensitivity of enzymes in a number of the fish species tested. Allozyme phenotypes at the PGM-2 locus in mosquitofish observed on test gels (0.9 mg Cu/L) suggests that two isoalleles, one copper-tolerant and one copper-sensitive, are present at this locus.
Microbial degradation of nitrogen, oxygen and sulfur heterocyclic compounds under anaerobic conditions: Studies with aquifer samples
Authors: Kuhn Elmar P. , Suflita Joseph M.
Published: March 2010

The potential for anaerobic biodegradation of 12 heterocyclic model compounds was studied. Nine of the model compounds were biotransformed in aquifer slurries under sulfate-reducing or methanogenic conditions. The nitrogen and oxygen heterocyclic compounds were more susceptible to anaerobic biodegradation than those compounds containing a sulfur heteroatom. Carboxy-substituted compounds were anaerobically metabolized more readily than unsubstituted or methylated analogues. In methanogenic incubations, 47 to 84% of the expected amount of carbon in pyridine, 4-picoline, nicotinic acid and 2-thiophene carboxylic acid was recovered as methane. In contrast, only small amounts of methane were detected in aquifer slurries amended with compounds containing an oxygen heteroatom, even though a decrease in the parent substrate concentration occurred. Pyridine, 2-picoline and 4-picoline were biotransformed within three months under sulfate-reducing conditions. However, longer incubation times were required for the degradation of these substrates in methanogenic aquifer slurries. A literature survey reveals the widespread contamination of ground waters with heterocyclic compounds from waste management practice and fossil-fuel-related industries.
Aqueous chlorination of resorcinol
Authors: Heasley Victor L. , Burns Michael D. , Kemalyan Nathan A. , McKee Tawnya C. , Schroeter Hinako , Teegarden Brad R. , Whitney Scott E. , Wershaw Robert L.
Published: March 2010

An investigation of the aqueous chlorination (NaOCl) of resorcinol is reported. The following intermediates were detected in moderate to high yield at different pH values and varying percentages of chlorination: 2-chloro-, 4-chloro-, 2,4-dichloro-, 4,6-dichloro- and 2,4,6-trichlororesorcinol. Only trace amounts of the intermediates were detected when the chlorination was conducted in the presence of phosphate buffer. This result has significant implications since resorcinol in phosphate buffer has been used as a model compound in several recent studies on the formation of chlorinated hydrocarbons during chlorination of drinking water. Relative rates of chlorination were determined for resorcinol and several of the chlorinated resorcinols. Resorcinol was found to chlorinate only three times faster than 2,4,6-trichlororesorcinol. The structure 2,4,6-trichlororesorcinol was established as a monohydrate even after sublimation. A tetrachloro or pentachloro intermediate was not detected, suggesting that the ring-opening step of such an intermediate must be rapid.
Environmental persistence and fate of fenoxaprop-ethyl
Authors: Toole Amy P. , Crosby Donald G.
Published: March 2010

The environmental persistence and fate of ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy]phen-oxy]propanoate (fenoxaprop-ethyl), a herbicide proposed for selective control of grasses in California rice, have been investigated under laboratory and field conditions. In the field, it dissipated rapidly from both water and soil, with half-lives in water <4 h and soil residues below detectability within 6 d. The photolysis half-life in sterile, distilled water was 269 · 19 h; in field water a combination of microbial and photochemical reactions resulted in a half-life of 29 · 2 h. Products included the corresponding acid, 6-chlorobenzoxazolinone, ethyl 2-(4-hydroxyphenoxy)propanoate and 2-(4-hydroxyphenoxy)propanoic acid. Hydrolysis was slow at pH 6.1 and 7.4 but resulted in a half-life of only 8.3 h at pH 9.1. Fenoxaprop-ethyl is essentially nonvolatile (Henry's Law constant = 3 × 10−7) and was bound moderately to soil (Koc = 6800). These properties represent a near optimum for pesticide persistence.
Comparison of on-site and laboratory toxicity tests: Derivation of site-specific criteria for un-ionized ammonia in a Colorado transitional stream
Authors: Nimmo Del Wayne R. , Link Denise , Parrish Loys P. , Rodriguez Glenn J. , Wuerthele William , Davies Patrick H.
Published: March 2010

Acute tests with fathead minnows (Pimephales prornelas Rafinesque), johnny darters (Etheostoma nigrum Rafinesque), white suckers (Catostomus commersoni Lacépède) and acute and chronic tests with Ceriodaphnia dubia were conducted to evaluate whether characteristics of the St. Vrain River in Colorado would ameliorate or enhance toxicity of un-ionized ammonia compared to laboratory (well) water and LC50 values found in the literature. Concurrently, tests were conducted on dilutions of Longmont, Colorado, wastewater to evaluate its toxicity in differing ammonia concentrations. Tests were conducted at two temperatures (approximately 6 and 20°C) to simulate seasonal differences.

LC50s for fishes in the St. Vrain River water were similar to LC50s in laboratory water, indicating there was no site water effect. LC50s derived for fishes tested in warm conditions were within a factor of about two or three of literature values. However, the constituents in or characteristics of the wastewater appeared to enhance ammonia toxicity. Literature values (LC50s) for resident aquatic organisms and the new LC50 value for johnny darters tested on-site were used to derive site-specific criteria for un-ionized ammonia. Greater sensitivities of species to ammonia at cold versus warm temperatures suggests that colder, low-flow conditions may be a critical period for warm-water aquatic communities with regard to ammonia toxicity.
Suppression of secretory rosette formation by PCBs in Lumbricus terrestris: An earthworm assay for humoral immunotoxicity of xenobiotics
Authors: Rodriguez-Grau Jorge , Venables Barney J. , Fitzpatrick Lloyd C. , Goven Arthur J. , Cooper Edwin L.
Published: March 2010

Research is part of an effort to develop surrogate immunoassays with the earthworm Lumbricus terrestris to assess immunotoxic potential of xenobiotics to mammals. Objective was to determine if an earthworm humoral immunoassay, secretory (S) rosette formation by coelomic leukocytes, is sensitive to a known mammalian immunotoxin, the polychlorinated biphenyl (PCB) Aroclor 1254®. Results are presented in terms of PCB exposure and tissue levels during uptake/depuration. Using 5-d filter paper contact exposure, LC50 and LD50 were 300 m̈g/cm2 and 1,140 m̈g/g dry mass. Nominal PCB exposure concentration of 5.0 m̈g/cm2 and actual tissue levels of 76 m̈g/g dry mass were sufficient to suppress S-rosette formation. Suppression and return of function followed PCB levels in coelomic leukocytes, the presumed site of toxicity. Compared to published mammalian data on immunoglobulin suppression by PCBs, the earthworm immunoassay appeared to be more sensitive.
Swimming behavior as an indicator of sublethal toxicity in fish
Authors: Little Edward E. , Finger Susan E.
Published: March 2010

Swimming behavior of fish is impaired by exposure to a diversity of contaminants. Gross aberrations in swimming can be qualitatively assessed while subtle changes in swimming behavior arising from sublethal exposures can be detected through a more detailed analysis of this response. Compared to other swimming behavior variables, the physical capacity to swim against water flow tends to be affected at relatively high toxicant concentrations and often presages mortality. Orientation to water flow, however, is altered at sublethal concentrations. Frequency of activity is a more sensitive measure in detecting contamination than measurements of survival alone. Alterations in swimming behavior have been detected during exposures to various contaminants at concentrations as low as 0.7 to 5% of their LC50 values and at concentrations that subsequently inhibited growth after longer periods of exposure. Analysis of swimming patterns provides even higher resolution for analysis of swimming behavior, and increased availability of the instrumentation necessary for such measurements should facilitate use of this approach. Fish swimming activity can easily be incorporated in test protocols to expand the sensitivity of standard toxicity tests.
A behavioral screening assay for Daphnia Magna: A method to assess the effects of xenobiotics on spacial orientation
Authors: Goodrich Mark S. , Lech John J.
Published: March 2010

We have developed a short-term, low-cost method of detecting changes in the orientative ability of Daphnia magna in response to xenobiotics. The method employs the reaction, a migration along the gradient, of D. magna to a light intensity gradient. The method was derived from techniques established to simulate and analyze migration patterns of zooplankton in the natural environment. Each test uses a minimum of 100 1- to 3-d old Daphnia exposed to a directional light beam within a circular chamber. The chamber is divided into eight sections, each containing 45° of arc. These quadrants can be isolated from each other, thus isolating eight groups of migrating Daphnia. Each test results in three endpoints: an average direction for the migration (mean angle), an index of the magnitude of random, undirected migration (r value) and a percentage of nonresponse. The method was validated by showing a positive dose-related response to a known neurotoxin, lindane. The method is sensitive to lindane, producing effects on orientation even at a concentration as low as 50 ppb. The effect of lindane was a dramatic increase in the random migration of dosed Daphnia, showing a less directed migration pattern than control. Implications of developing a behavioral test with Daphnia and its correlation with the natural environment are discussed, as well as its incorporation into the general toxicity screening strategy. Interpretative and comparative statistical analysis of the method's endpoints are presented and discussed.
Behavioral toxicity syndromes: A promising tool for assessing toxicity mechanisms in juvenile fathead minnows
Authors: Drummond Robert A. , Russom Christine L.
Published: March 2010

Fathead minnows (Pimephales promelas) were exposed to acutely toxic concentrations of organic chemicals under flow-through conditions at 25°C for 96 h. Changes in behavior and morphology were systematically recorded to develop a plan for classifying these chemicals. On this basis, three behavioral toxicity syndromes were evident. Each syndrome appears to represent a different general mode of toxic action. The hypoactivity syndrome, reflecting narcosis, is characterized by depressed locomotor activity, loss of startle response and very dark body coloration. The hyperactivity syndrome, representing metabolic dysfunction (e.g., uncouplers of oxidative phosphorylation), is characterized by greatly accelerated locomotor activity, overreaction to stimuli and increased ventilatory activity. The physical deformity syndrome, indicative of neurological dysfunction (e.g., AChE inhibition), is characterized by a high incidence of convulsions, tetany, scoliosis/lordosis and hemorrhage in the vertebral area. This classification approach also should be useful to help delineate specific, underlying mechanisms or sites of chemical action.
Behavioral responses of marked snails as indicators of water quality
Authors: Burris Janet A. , Bamford Martha S. , Stewart Arthur J.
Published: March 2010

Behavioral responses of the common stream-dwelling operculate snail Elimia clavaeformis were used to provide information about streamwater quality in in situ tests. These snails were found to be advantageous for such tests because they can be collected easily, individually marked, and transferred to other stream sites for release and recapture experiments.

In noncontaminated stream sites, Elimia tended to disperse upstream. The rate of net movement was variable, but typically ranged from 0.5 to 5 m/d. Water velocity and food level influenced the movement patterns of the snails in 24- and 48-h field experiments in noncontaminated stream sites. Rates of movement in the laboratory were temperature dependent, and increased from about 1.0 cm/min at 9°C to 2.2 cm/min at 24°C.

In contaminated streams, snails showed clear evidence of stress: They moved downstream, and in some sites either withdrew into the shell or were unable to retract the foot or attach to a substrate. The maximum distance that Elimia traveled downstream in 24 h in a contaminated stream site was 17.5 m.

In laboratory streams, Elimia moved downstream when exposed to 0.02 mg/L total residual chlorine (TRC); the time required to immobilize these snails declined rapidly as TRC concentration increased. Behavioral characteristics of snails that may be useful for water quality assessments include turnover time (the time needed for a snail to right itself after being turned onto its back), the rate and direction of dispersal or immobilization.
Toxicokinetics of selected polycyclic aromatic hydrocarbons in rainbow trout following different routes of exposure
Authors: Kennedy Christopher J. , Law Francis C. P.
Published: March 2010

The toxicokinetics and bioavailabilities of 2-methylnaphthalene (2-MN), fluorene and pyrene were studied in rainbow trout (Salmo gairdners) implanted with an indwelling cannula in the dorsal aorta. After intraarterial injection of one of the polycyclic aromatic hydrocarbons (PAHs) (10 mg/kg) to trout, chemical concentration in the blood was found to decline triphasically with time. The terminal half-lives of elimination from the blood for 2-MN, fluorene and pyrene were 9.6, 10.5 and 12.8 h, respectively. The toxicokinetics of the PAHs in trout were best described by a three-compartment open model with the central compartment and the deep peripheral compartment representing the blood and fatty tissues of trout, respectively. The PAHs were metabolized by trout mainly to water-soluble metabolites which were excreted into the urine and bile. When trout were exposed to water containing 2-MN, fluorene or pyrene (0.5 mg/L), the chemical was detected almost immediately in the blood. The apparent bioavailabilities of 2-MN, fluorene and pyrene in trout were 20, 36 and 35%, respectively. In contrast, little or no unchanged chemical was detected in the blood of trout following intragastric administration of 2-MN, fluorene or pyrene (50 mg/kg). These results indicate that the PAHs are absorbed systemically by trout via the branchial route at rates much faster than that of the oral route.
Rate-limiting barriers to xenobiotic uptake by the gill
Authors: Hayton William L. , Barron Mace G.
Published: March 2010

Waterborne xenobiotics enter fish and other aquatic species primarily by transfer across the gill epithelium. Potential barriers to uptake include water flow across the gill, diffusion across the gill epithelium and the overlying aqueous stagnant layer and blood flow through the gill (cardiac output). In general, for any particular chemical, only one of the barriers is operative with the resistance offered by the others being negligible. The rate-limiting barrier is determined by the physico- and biochemical properties of the substance: molecular size, lipophilicity, binding to blood proteins and formed elements. The resistance of each barrier is affected differently by variables such as temperature, molecular size, lipophilicity and body size of the animal. When the resistance offered by the gill barriers is low, uptake may be controlled by transfer to storage tissues, e.g., by blood flow to adipose tissue.
A simple flow-limited model for exchange of organic chemicals at fish gills
Authors: Erickson Russell J. , McKim James M.
Published: March 2010

A mathematical model for the exchange of organic chemicals by fish gills was formulated based solely on the limitations imposed by the flows of water and blood into the gills. For large rainbow trout, this model was found to closely follow the magnitude and trends of observed gill uptake rates over a range of octanol/water partition coefficient from 1 to 106. Observations averaged only about 30% less than model predictions. This modest lack-of-fit is presumably due to the effects of diffusional barriers and ionization which would further limit uptake, although uncertainties in model parameters and data are likely also partly responsible. This analysis suggests that these basic physiological parameters are of major importance in the regulation of exchange at fish gills and should be accounted for in more detailed toxicokinetic models. Also, this simple model could by itself be useful for approximate assessments of accumulation of organic chemicals by fish.
Toxicokinetics of PAHs in Hexagenia
Authors: Stehly Guy R. , Landrum Peter F. , Klemm Christina , Henry Mary G.
Published: March 2010

The accumulation kinetics of two waterborne polycyclic aromatic hydrocarbons (PAHs), benzo[a]pyrene (BAP) and phenanthrene (PHE), were studied in the mayfly nymph (Hexagenia limbata).

The uptake clearance decreased while the bioconcentration of BAP increased with an increase in weight of the H. limbata nymph. The relationship between uptake clearance and bioconcentration for PHE was variable, and bioconcentration was greater for the heavier animals.

Two kinetic models were used to evaluate the effect of nymph weight on disposition of PAHs: (a) the amount-uptake clearance model, similar to models most frequently used in environmental toxicology; and (b) a clearance-volume model, similar to models used in clinical pharmacology. The two models gave similar predictive results but were different in a few cases. These differences in common parameter estimation probably resulted from methodologies used and high data variability rather than the models themselves, since they are mathematically equal. Some of the parameters are unique to each of the models and are defined and described.

The clearance of oxygen from water is inversely and linearly related to the weight of the mayfly nymphs, but oxygen clearances were always much less than the uptake clearances of the PAHs. The high PAH uptake clearance compared to oxygen clearance implies a greater surface area or efficiency for PAH accumulation from water.
Bioaccumulation and biotransformation of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish
Authors: Opperhuizen Antoon , Sijm Dick T. H. M.
Published: March 2010

In spite of their hydrophobicity, not all polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners accumulate significantly in fish or other aquatic organisms. This is found both in laboratory experiments and in organisms that are sampled in the natural environment. Hitherto, this congener-specific accumulation could not adequately be explained or predicted.

Many PCDDs and PCDFs with four or more chlorine atoms, such as octachlorodibenzo-p-dioxin, are taken up very slowly, if at all, during aqueous exposure. Furthermore, the uptake rates after dietary exposure of these congeners are significantly less than those of other chlorinated aromatic hydrocarbons with comparable hydrophobicity, such as polychlorinated benzenes and biphenyls. A lack or a low rate of membrane permeation may help to explain this phenomenon.

For several higher chlorinated congeners and for most of the lower chlorinated dioxins and furans, the rates of uptake after dietary and aqueous exposure are comparable to those of other hydrophobic aromatic hydrocarbons. The relatively low bioconcentration and biomagnification factors of these lower chlorinated PCDDs and PCDFs should thus be explained by high rates of excretion, probably by biotransformation. In several studies, polar metabolites have been identified. Furthermore, in fish in which the cytochrome P-450 system was inhibited with piperonylbutoxide, the bioconcentration factor of 2,8-dichlorodibenzo-p-dioxin was significantly higher than that in fish which were not pretreated with the blocking agent. These results support the hypothesis that biotransformation is of paramount importance for the bioaccumulation of several PCDDs and PCDFs.
5-Methyl deoxycytidine content of DNA from bluegill sunfish (Lepomis macrochirus) exposed to benzo[a]pyrene
Authors: Shugart Lee R.
Published: March 2010

The 5-methyl deoxycytidine (m5-dCyd) content of DNA from bluegill sunfish chronically exposed to benzo[a]pyrene at a concentration of 1 μg/L in their water for a period of 40 d was quantified by cation exchange chromatography. Hypomethylation, as measured by the loss of m5-dCyd from the DNA, occurred shortly after benzo[a]pyrene (BaP) exposure and continued even upon termination of exposure conditions. The onset and persistence of hypomethylation was found to be correlated with other types of DNA-damaging events such as strand breaks and DNA adduct formation. These observations suggest that changes in DNA integrity, including hypomethylation, are indicative of a biological response to genotoxic agents.
Determination of the ventilation rates of interstitial and overlying water by the clam Macoma nasuta
Authors: Winsor Martha H. , Boese Bruce L. , Lee Ii Henry , Randall Robert C. , Specht David T.
Published: March 2010

The ventilation rates of interstitial and overlying water for the deposit-feeding, tellinid clam Macoma nasuta (Conrad) were determined using two water-soluble dyes to differentiate between the two water sources. A unique exposure chamber, the clambox, was used to separate the inhalant and exhalant siphons of the clam, allowing measurements of dye fluxes and total water ventilated. The results suggested that interstitial water constituted very little (4%) of the total amount of water ventilated by this clam. Factors that could affect the importance of interstitial water as a pollutant uptake route and how these might vary among pollutants or infaunal species are discussed.
Ground water transport of hydrophobic organic compounds in the presence of dissolved organic matter
Authors: Kan Amy T. , Tomson Mason B.
Published: March 2010

The effects of dissolved organic matter (DOM) on the transport of hydrophobic organic compounds in soil columns were investigated. Three compounds (naphthalene, phenanthrene and DDT) that spanned three orders of magnitude in water solubility were used. Instead of humic matter, molecularly well-defined DOM represented by Triton X-100, a nonionic industrial detergent, and bovine serum albumin protein were used. In batch isotherm studies, the sorption of naphthalene to both model DOMs appeared to be hydrophobic in nature and quantitatively similar to the binding to humic materials. Equations were derived to model the enhanced transport of organic compounds by DOM based on octanol/water partition coefficients, Kow. For a specific soil and DOM level, it was shown theoretically and experimentally that all organic compounds with Kow values above a specific value should move at the same rate in ground water. In some situations, DOM can increase the movement of highly hydrophobic compounds, such as DDT, by a factor of a thousand or more. This enhanced transport in the presence of DOM can either be a problem, as with ground water contaminant spreading, or a benefit, as with contaminated aquifer cleanup.
QSARs based on statistical design and their use for identifying chemicals for further biological testing
Authors: Tosato Maria Livia , Marchini Silvia , Passerini Laura , Pino Anna , Eriksson Lennart , Lindgren Fredrik , Hellberg Sven , Jonsson Jörgen , Sjöström Michael , Skagerberg Bert , Wold Svante
Published: March 2010

The paper provides an overview of how quantitative structure-activity relationship (QSAR) studies may represent a tool for predictions of toxic/ecotoxic effects of chemicals and identification of potentially hazardous ones. The paper is divided into two parts: theory and application. In the first part, the issues discussed are: the philosophy of QSAR, the conditions that must be fulfilled for constructing sound models and a strategy to establish priorities for further toxicological testing. In the second part, illustrations are reported regarding how a number of environmentally significant chemicals is distributed into chemical classes that meet QSAR criteria for modeling and how QSAR studies are carried out. For this latter purpose, four classes of chemicals are considered and emphasis is placed on the selection of the training sets and the validation of the models.
Characterization of the reducing properties of anaerobic sediment slurries using redox indicators
Authors: Tratnyek Paul G. , Lee Wolfe N.
Published: March 2010

The reduction of six redox indicators in anaerobic sediment slurries was studied by observing the disappearance of the color of the oxidized forms. The reaction kinetics were first-order in concentration of the oxidized form of the indicator and the reducing agents were sediment associated. The rate of indicator reduction reflects the standard potential of the indicator couple, the structure of the indicator moiety reduced and the potential and capacity of reducing agents in the sediment slurry. The relative reduction rates of the indicators suggest that anaerobic sediment systems contain concentrations of mild reducing agents that are available to react rapidly with substrates that are easily reduced. However, more refractory substrates require strong reducing agents that are gradually produced, probably as a result of microbial metabolism.
Adsorption of dodecyltrimethylammonium chloride (C12TMAC) to river sediment
Authors: Hand Vincent C. , Rapaport Robert A. , Wendt Richard H.
Published: March 2010

Adsorption distribution ratios for [14C]-dodecyltrimethylammonium chloride (C12TMAC) to sediment have been measured at realistic environmental concentrations. As observed by investigators of hydrophobic organic and metal sorption, the distribution ratio was found to be inversely related to the sediment concentration. The value of the distribution ratios varied from 440 L/kg at a sediment concentration of 248,000 mg/L up to 251,000 L/kg at a sediment concentration of 230 mg/L. Data can be fit to Freundlich isotherms with slopes ≤1. Data are consistent with an ion-exchange mechanism.