bluuebunny/crossref_metadata_2025 huggingface dataset:
The european system of standardized legal tests for assessing the biodegradability of chemicals
Authors: Nyholm Niels
Published: March 2010

A brief overview is given of the approach to biodegradation testing adopted by the European Economic Community (EEC) as part of the legislation on new chemicals. The tiered system of screening and simulation tests is outlined and the various tests are discussed briefly. It is concluded that the test strategy is logical and cost-effective, but that ongoing work to further harmonize and revise screening tests for ready biodegradability must be completed before these tests perform satisfactorily. The principles governing simulation tests should be further developed, and, in particular, the importance of the applied concentration of test chemical should be addressed.
Silica encapsulation reduces bioavailability
Authors: Pier Stanley M. , Gallo Michael A. , Umbreit Thomas H. , Connor Thomas H. , Gray Donald , Cappelleri Frank A.
Published: March 2010

Lead chromate pigments can be encapsulated within an amorphous silica coating. This reduces both the chemical teachability and the biological availability of the constituents. The chromate moiety is inactive in in vitro mutagenicity assays, even in the presence of a strong chelating solubilizer under conditions where the unencapsulated material gives positive results. Rodent feeding studies demonstrate much reduced absorption of both lead and chromium from the encapsulated lead chromate compared to the analogous unencapsulated material. Encapsulation also reduces the leachability of both lead and chromium in tests used to define the applicable environmental disposal methods for lead chromate pigments. These findings have important implications for health and environmental issues surrounding the use of lead chromate as a pigment material.
Bond contribution method for estimating henry's law constants
Authors: Meylan William M. , Howard Philip H.
Published: March 2010

Bond contribution values, used to estimate Henry's law constant (HLC) (air-to-water partition coefficient) from chemical structure, have been determined for 59 chemical bonds by a least-square analysis of known HLCs for 345 organic compounds. A correlation coefficient (r2) of 0.94 was determined for the relationship between known LWAPCs (log water-to-air partition coefficients) and bond estimated LWAPCs for the 345 compound data set. The correlation coefficient increases to 0.97 when quantified correction factors are applied to selected chemical classes. The ability of the bond method to estimate LWAPCs is demonstrated by a validation test set of 74 diverse and structurally complex compounds that were not included in the least-squares analysis. The correlation coefficient for the validation set is 0.96.
Acid-volatile sulfide as a factor mediating cadmium and nickel bioavailability in contaminated sediments
Authors: Ankley Gerald T. , Phipps Gary L. , Leonard Edward N. , Benoit Duane A. , Mattson Vincent R. , Kosian Patricia A. , Cotter Anne M. , Dierkes Joseph R. , Hansen David J. , Mahony John D.
Published: March 2010

We investigated the influence of sulfide, measured as acid-volatile sulfide (AVS), on the bioavailability of cadmium and nickel in sediments. Seventeen samples from an estuarine system heavily contaminated with cadmium and nickel were analyzed for AVS and simultaneously extracted metals (SEM) and tested in 10-d exposures with the amphipod Hyalella azteca and the oligochaete Lumbriculus vanegatus. Molar SEM (cadmium + nickel)/AVS ratios in the sediments ranged from less than one to greater than 200, with several in the range of 1 to 10. Samples with SEM/AVS ratios greater than one were consistently toxic to Hyalella azteca, whereas sediments with ratios less than one were not. Lumbriculus variegatus was less sensitive to the test sediments than Hyalella azteca, which was consistent with their relative sensitivity to cadmium and nickel in water-only exposures. SEM/AVS ratios in the sediments also appeared to be important in determining bioaccumulation of metals by Lumbriculus variegatus. These results support other studies with metal-spiked samples in demonstrating the importance of AVS in determining metal bioavailability in sediments and suggest that AVS normalization is a reasonable means for assessing the hazard of some sediment-associated metals to aquatic ecosystems.
Differences in acute toxicity test results of three reference toxicants on Daphnia at two temperatures
Authors: Lewis Philip A. , Horning William B.
Published: March 2010

Ten 48-h static acute toxicity tests were conducted with Daphnia magna Straus and Daphnia pulex Leydig with each of the three reference toxicants — sodium dodecyl sulfate (SDS), sodium pentachlorophenate (NaPCP), and cadmium (Cd) (as CdCl2) — at 20 and 26°C to investigate the effect of temperature on test results at the temperature extremes usually encountered during field studies. The mean 48-h LC50 value for SDS with Daphnia pulex at 26°C was lower (10.2 mg/L) than at 20°C (12.6 mg/L), but the difference was not significant (α = 0.05). For Daphnia magna the mean LC50 was significantly (α = 0.05) lower at 26°C (10.8 mg/L) than at 20°C (13.5 mg/L). Sensitivity of either species to NaPCP was not significantly different (α = 0.05) at the two temperatures. The data show a fourfold increase in sensitivity to Cd at the higher temperature with Daphnia magna (mean LC50 = 0.038 mg/L at 20°C and 0.009 mg/L at 26°C) and a sevenfold increase with Daphnia pulex (mean LC50 = 0.042 mg/L at 20°C and 0.006 mg/L at 26°C). These data indicate that toxicity tests conducted at 20 and 26°C may give significantly different results with Daphnia. Because test precision, control survival, and the likelihood of obtaining valid tests are better at 20°C, that temperature is recommended for acute toxicity tests with Daphnia.
Effects of spiked exposure to an oil dispersant on the early life stages of four marine species
Authors: Singer Michael M. , Smalheer Deborah L. , Tjeerdema Ronald S. , Martin Michael
Published: March 2010

Spiked exposure, continuous flow toxicity tests using the oil dispersant Corexit 9527® were performed during the early life stages of four California marine species. Test chambers containing sensitive life stages of the giant kelp (Macrocystis pyrifera), the red abalone (Haliotis rufescens), a kelp forest mysid (Holmesimysis costata), and the topsmelt (Atherinops affinis) were inoculated with concentrated dispersant, then allowed to flush with clean, filtered seawater Spectrophotometric monitoring of tests showed dispersant levels diminishing to below detection limits within 5 to 6 h or less Results showed Hahotis to be the most sensitive species tested, with Atherinops being least sensitive in terms of no-observed effect concentration (NOEC) and Holmesimysis being least sensitive in terms of median effect concentration, Macrocystis was intermediate in both measures. When spiked exposure toxicity results were compared to those of previously reported constant-exposure tests, no consistent conversion factor that might relate spiked- and constant-exposure toxicity data was found.
Collection of ammonia in indoor air by means of a weak cation exchange cartridge
Authors: Risner C. H. , Conner J. M.
Published: March 2010

An active sampling method based on a solid-phase collection medium was used to determine ammonia concentrations in indoor air. A weak cation exchange cartridge was used to collect ammonia, which was then eluted from the cartridge with 0.02 M HCl and determined by cation exchange chromatography (CEC) with conductivity detection. The method was applied to quantify the ammonia in environmental tobacco smoke (ETS) and is compared to an impinger collection technique. The method was reproducible with a relative standard deviation of 2.0%. Percent recovery is about 98%. Analyses of samples collected in a variety of situations showed that ammonia concentrations vary. With a relatively short sampling time of 0.5 to 1 h, this procedure was capable of detecting ammonia above 5 μg m−3 under the sampling conditions.
Sensitivity to uranium of six species of tropical freshwater fishes and four species of cladocerans from Northern Australia
Authors: Bywater John F. , Banaczkowski Robyn , Bailey Megan
Published: March 2010

The toxicity of uranium to the tropical freshwater fishes —black-banded rainbowfish (Melanotaenia nigrans), chequered rainbowfish (Melanotaenia splendida inornata), Mariana's hardy-head (Craterocephalus marianae), delicate blue-eye (Pseudomugil tenellus), reticulated perchlet (Ambassis macleayi), and purple-spotted gudgeon (Mogurnda mogurnda) — and the cladocerans — Diaphanosoma excisum, Latonopsis fasciculata, Dadaya macrops, and Moinodaphnia macleayi — was measured under standard conditions in natural creek water. The fishes' 96-h LC50s for uranium were 1.7 and 1.9 mg/L for 7- and 90-d-old black-banded rainbowfishes, 2.66 and 3.46 mg/L for 7- and 90-d-old chequered rainbowfishes, 1.22 mg/L for Mariana's hardyhead, 0.73 mg/L for delicate blue-eyes, 0.8 mg/L for reticulated perchlet, and 1.11 and 1.46 mg/L for 7- and 90-d-old purple-spotted gudgeon. The cladocerans' 24-h LC50s for uranium were 1.0 mg/L for Diaphanosoma excisum, 0.41 mg/L for Latonopsis fasciculata, 1.10 mg/L for Dadaya macrops, and 1.29 mg/L for Moinodaphnia macleayi. Larval purple-spotted gudgeon, reticulated perchlets, and Moinodaphnia macleayi were identified as the most suitable species for toxicity testing.
Effects of pesticides on songbird productivity in conjunction with pecan cultivation in southern georgia: A multiple-exposure experimental design
Authors: Patnode Kathleen A. , White Donald H.
Published: March 2010

A prototypic experimental design was used to assess sublethal effects of multiple and varied organophosphates and carbamates on reproduction in birds. The design allowed for classification of pesticide exposure according to toxicity of applied compounds and type and frequency of applications. Daily survival rates (DSRs) of nests, eggs, and nestlings were determined for northern mockingbirds (Mimus polyglottos), brown thrashers (Toxostoma rufum), and northern cardinals (Cardinalis cardinalis) nesting along edges of pecan orchards and row crops in southern Georgia. Egg and nestling DSRs for all species combined varied inversely (P < 0.05) with exposure. Nestling weight gain was reduced (P < 0.05) with increasing exposure levels in northern mockingbirds and brown thrashers. Parenting behavior in northern cardinal and northern mockingbird did not differ (P > 0.05) among three exposure levels. Brain cholinesterase activities were age-dependent and substantiated adult, but not nestling, exposure. Results suggest that increasing exposure to pesticides may reduce songbird productivity.
Integrity of five granular insecticide carriers in house sparrow gizzards
Authors: Best Louis B. , Gionfriddo James P.
Published: March 2010

This study evaluated the integrity of five granular insecticide carriers in gizzards of house sparrows (Passer domesttcus). Bentonite clay and gypsum granules disintegrated very rapidly in gizzards, heat-treated clay and corncob particles were retained in gizzards for several hours, and silica granules were the most persistent. Granule integrity may influence granule consumption rates and thus should be considered in assessments of avian exposure to granular insecticides.
Assessing the toxicity of freshwater sediments
Authors: Burton G. Allen
Published: March 2010

The science of sediment toxicology essentially began in the late 1970s. It was largely a product of dredging concerns and recognition of widespread contamination of sediments. During the past few years, sediment toxicity research activity has increased dramatically. Currently, most tests are of an acute nature with fewer available for determining sublethal endpoints of chronic toxicity. Test systems of single and multiple species have included most levels of biological organization in aquatic ecosystems and have been conducted in the laboratory on whole sediments, interstitial waters, elutriates, or other extractable fractions under a wide variety of conditions. Evaluations of methodological effects and comparisons with in situ toxicity using surrogate test species and indigenous communities have, on occasion, shown significant differences in test responses. These differences may be attributed to laboratory-controlled parameters (e.g., light, species, life stage, exposure conditions, test phase, spiking method); sampling and laboratory-induced disruption of sediment integrity; alteration of toxicant partitioning due to manipulations and temporal effects; and failure to recognize other influencing ecosystem variables (e.g., organism niche and life cycle, sediment partitioning and gradient dynamics, physicochemical and biological process integration, biotic and abiotic disturbances, micro- and macrobiota patches, food-web interactions). Optimizing and standardizing test methods will require further studies of these variables to improve inter-laboratory comparisons and ecosystem validity. Despite the many unknowns that exist, a variety of sediment toxicity tests have been effectively used in assessing toxicant contamination by measuring the bioavailable fraction of the in-place pollutants. The optimal assays vary with the study and its objectives. Intergrative studies using several chemical, community, and toxicity measures are currently the most effective at defining ecosystem perturbations.
Experimental designs for aquatic mesocosm studies: A comparison of the “anova” and “regression” design for assessing the impact of tetrachlorophenol on zooplankton populations in limnocorrals
Authors: Liber Karsten , Kaushik Narinder K. , Solomon Keith R. , Carey John H.
Published: March 2010

Two experimental designs were compared for assessing the impact of a commercial 2,3,4,6-tetrachlorophenol formulation (DIATOX®) on zooplankton abundance in a set of limnocorrals. The first design, based on blocked analysis of variance (ANOVA) procedures, used treatments of 0, 0.75, and 1.50 mg/L DIATOX with three replicates of each. The second design, based on regression procedures, had eight treatments ranging from 0 to 7.3 mg/L DIATOX with no replication.

For the ANOVA experiment, a conventional ANOVA by day revealed significant impact on all zooplankton taxa investigated. Impact and time to recovery were greater with the 1.50-mg/L DIATOX treatment, and rotifers were more sensitive than macrozooplankton. A repeated-measures ANOVA, used to correct for pretreatment variability, revealed additional differences as significant. The ANOVA design permits easy assessment of impact at the chosen toxicant levels, but no conclusion can be drawn regarding the no-effect concentration (NEC) for major zooplankton taxa.

For the regression experiment, linear dose—response relationships were used to estimate the NEC by inverse regression analysis. NECs for major zooplankton taxa and dominant species ranged from 0.28 mg/L DIATOX for immature Copepoda to 0.50 mg/L DIATOX for combined Cladocera. In 9 of 14 cases, however, the estimated EC50 ≤ NEC, an indication that an increased number of lower test concentrations were needed. The regression design offers a promising alternative to the common ANOVA design and allows for the estimation of specified end points such as the NEC and EC50.
Use and efficiency of ethylene glycol monomethyl ether and monoethanolamine to trap volatilized [7-14C]naphthalene and 14CO2
Authors: Abbott C. K. , Sims R. C. , Sorensen D. L.
Published: March 2010

Separation of radiolabeled CO2 from volatile parent compound(s) or degradation products in air from biodegradation microcosms has been done by using solubility in alkaline vs. nonpolar solvents or solutions. However, trapping solvents or solutions used to collect radiolabeled CO2 may absorb some volatile intermediate products or the volatilized parent compound. Similarly, solvents used to trap volatile radiolabeled degradation intermediates or volatile parent compound may absorb some radiolabeled CO2. If this lack of absorption specificity is significant, the clear interpretation of radioactivity-counting analyses may be compromised.

A procedure designed to separate volatilized [7-14C]naphthalene and 14CO2 from the same air stream was evaluated for its efficiency. Ethylene glycol monomethyl ether (EGME) effectively trapped naphthalene (98.6% recovery) but retained approximately 0.8% of the 14CO2, whereas monoethanolamine (MEA):methanol:scintillation cocktail solution trapped approximately 99.5% of the naphthalene and virtually 100% of the CO2. Preliminary studies of the efficiency of trapping solutions for parent compounds and mineralized CO2 should be made before conclusions are made concerning the extent or rate of mineralization based on the amount of radiolabeled carbon retained in a trapping solution.
The influence of organic matter quality on the toxicity and partitioning of sediment-associated fluoranthene
Authors: Dewitt Theodore H. , Jones Jill K.P. , Ozretich Robert J. , Swartz Richard C. , Lamberson Janet O. , Schults Donald W. , Ditsworth George R. , Smith Lawrence M. , Hoselton Laura
Published: March 2010

Organic matter in sediment is derived from many sources, including dead plants and animals, fecal matter, and flocculated colloidal organic matter. Chemical partitioning and toxicity of nonpolar organic contaminants is strongly affected by the quantity of sediment organic matter. The purpose of this study was to determine whether the quality of sediment organic matter affects partitioning and bioavailability of such contaminants.

A base substrate, amended to a consistent organic carbon level (nominally 0.4%, measured 0.35% ± 0.11 sd POC [particulate organic carbon]) with five types of organic matter (a macrophyte, fecal matter of two invertebrate species, suspended particulate organic matter, and an organic-rich mud), was spiked with serial concentrations of the polynuclear aromatic hydrocarbon, fluoranthene. After a five-week equilibration period, the toxicity of the spiked substrates to an infaunal amphipod, Rhepoxynius abronius, was measured, and the distribution of fluoranthene between particulate and interstitial water phases (including total and freely dissolved interstitial water phases) was determined.

The range of acute toxicity among organic matter–source treatments was small when based on total sediment concentrations (11.1–19.1 mg fluoranthene per kilogram dry sediment, nominal). Partitioning of fluoranthene between particulate-sorbed and interstitial water phases was not affected by organic matter quality, except when the source was fresh plant material. This variability may have been due to qualitative differences in the particulate/interstitial water partitioning in plant material as a source of sedimentary organic matter or an artifact in the method used to determine freely dissolved, interstitial water fluoranthene concentrations. Equilibrium partitioning models accurately predicted interstitial water concentrations of fluoranthene for the nonplant substrates once corrections were made for the solubility of fluoranthene in seawater. Our data suggest that equilibrium partitioning–based sediment quality criteria for fluoranthene may not need to correct for the quality of organic carbon in sediments and that these criteria can be applied to sediments with a particulate organic carbon content as low as 0.3%.
An example of the identification of diazinon as a primary toxicant in an effluent
Authors: Amato Joseph R. , Lukasewycz Marta T. , Robert Eric D. , Mount Donald I. , Durhan Elizabeth J. , Ankley Gerald T.
Published: March 2010

A toxicity identification evaluation (TIE) conducted on a municipal wastewater discharge from the southeast United States was part of a research project aimed at developing U.S. Environmental Protection Agency (EPA) TIE methods for acutely toxic effluents. The effluent consistently exhibited acute toxicity to Ceriodaphnia dubia but not to fathead minnows (Pimephales promelas). Toxicity characterization procedures revealed that the primary toxicant was a nonpolar organic. Toxicity was recovered through C18 solid-phase extraction and concentration steps. Gas chromatography–mass spectroscopy of these concentrates revealed the presence of diazinon (O, O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate). Diazinon concentrations in whole effluent, determined by GC analyses, correlated well with the toxicity measurements of each sample. Relative species sensitivity also implicated diazinon as the primary toxicant. This study illustrates the successful application of EPA TIE methodologies for identifying a nonpolar organic toxicant in a complex effluent. The significance of detecting diazinon at acutely toxic concentrations in municipal wastewater may indicate a more widespread problem in this region of the United States. This toxicity problem may be attributed to the chemical characteristics of diazinon and its applications.
Testing sediment toxicity in chesapeake bay with the amphipod Leptocheirus plumulosus: An evaluation
Authors: Schlekat Christian E. , Mcgee Beth L. , Reinharz Eli
Published: March 2010

Organisms selected for testing the toxicity of estuarine sediments must exhibit sensitivity to toxicants while remaining tolerant of wide ranges of salinities and sediment characteristics. The amphipod Leptocheirus plumulosus Shoemaker is an ecologically important infaunal inhabitant of Chesapeake Bay sediments. Leptocheirus plumulosus was exposed to a range of salinities and sediments varying in physical composition for up to 28 d in separate experiments to determine effects of natural environmental variables on amphipod survival and reproduction. No significant differences in adult survival were observed among salinity treatments ranging from 1.5 to 32 ppt or among sediment treatments varying in particle size and organic content. Significant effects on reproductive end points were detected, indicating the potential for incorporating sublethal end points into the bioassay. Acute 96-h LC50 values for aqueous cadmium at a salinity of 6 ppt were determined for Leptocheirus plumulosus and the amphipod Hyalella azteca Saussure, an organism commonly used in freshwater sediment toxicity tests. The LC50 values were 0.30 mg Cd per liter and 0.19 mg Cd per liter for Leptocheirus plumulosus and Hyalella azteca, respectively.
Assessment of methods for estimating ecological risk in the terrestrial component: A case study at the baird & mcguire superfund site in holbrook, massachusetts
Authors: Menzie Charles A. , Burmaster David E. , Freshman Jonathan S. , Callahan Clarence A.
Published: March 2010

Predictive, bioassay, and field methods were compared with regard to assessing conditions and risks to terrestrial biota at a Superfund site contaminated with pesticides. Research indicated that predictive methods could result in large uncertainties, especially when attempting to estimate food chain transfer from soil to higher trophic levels (birds and mammals). Of the examined predictive methods, the soil-to-earthworm model yielded results that agreed best with field observations and literature values. Laboratory and in-field bioassays on soils provided good information on the potential toxicity of soils and the potential for bioaccumulation. In-field bioassay tests with earthworms were useful for defining the spatial distribution of toxic soils at the site as well as for indicating potential bioaccumulation in invertebrates. An attractive feature of in-field bioassays is that samples do not have to be removed from the field and assessments can begin to be made in the field. The importance of performing reality checks by conducting field studies was clearly demonstrated in our study with regard to the soil invertebrate community as well as birds and mammals. The main advantage of the field studies is that they provide direct information on conditions and thus aid in the interpretation or application of laboratory data. Difficulties were encountered in the conduct of population studies of the birds and mammals. Therefore, although site surveys of birds and mammals provide gross indications as to the presence and diversity of animals, it is probably more useful to rely on measures of residues and biomarkers to assess potential exposures and the possibility of subtle effects. Overall, it appears that ecological risk assessments at Superfund sites are best conducted by using a mix of predictive, laboratory, and field methods.
Application of QSARs, extrapolation and equilibrium partitioning in aquatic effects assessment. I. Narcotic industrial pollutants
Authors: Van Leeuwen Cees J. , Van Der Zandt Peter T. J. , Aldenberg Tom , Verhaar Henk J.M. , Hermens Joop L.M.
Published: March 2010

Quantitative structure–activity relationship (QSAR) estimates of toxicity of narcotic chemicals for 19 species of bacteria, algae, fungi, protozoans, coelenterates, rotifers, molluscs, crustaceans, insects, fish, and amphibians were used to predict no-effect levels (NELs) at the ecosystem level by means of recently developed extrapolation methods. Equilibrium partitioning theory was used to derive NELs for aquatic sediments and internal toxicant concentrations for aquatic organisms. A simple table is given from which NELs for narcotic chemicals for water, sediment, and residues in biota can be predicted on the basis of only the octanol/water partition coefficient and molecular weight. The method may be applied to setting quality criteria for the aquatic environment and to ecotoxicological interpretation of (bio)monitoring data. Calculations were carried out for 102 narcotic compounds.
Reductive transformations of halogenated aromatic hydrocarbons in anaerobic water-sediment systems: Kinetics, mechanisms and products
Authors: Peijnenburg Willie J.G.M. , Hart Maarten J. 't , Den Hollander Henri A. , van de Meent Dik , Verboom Hans H. , Wolfe N. Lee
Published: March 2010

The degradation of several classes of halogenated aromatic hydrocarbons in methanogenic sediment-water systems was examined in laboratory studies. Several transformation processes were shown to occur, leading to formation of a variety of products. In the study a clear distinction could be made between transformation processes taking place immediately upon incubation of the compounds and processes taking place after a characteristic period of varying length. γ-Irradiation was used to quench biological reactions and thus assess the impact of those processes on the overall rates of degradation of the studied compounds. The kinetics of both the initial and the final processes were pseudo-first-order, with half-lives ranging from <0.46 d to no detectable degradation for a number of multiply halogenated benzenes. Compounds were selected with the aim of obtaining a maximum variation in chemical reactivity and physical properties. The sediments were selected with the aim of assessing several environmental factors influencing the kinetics of reduction.
Using ratios of stable nitrogen isotopes to estimate bioaccumulation and flux of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in two food chains from the Northern Baltic
Authors: Broman Dag , Rolff Carl , Näf Carina , Zebühr Yngve , Fry Brian , Hobbie John
Published: March 2010

Presented in this study is a new method to quantitatively estimate in situ biomagnification of organic contaminants that uses ratios of naturally occurring stable isotopes of nitrogen to classify trophic levels of organisms from one littoral and one pelagic food chain in the northern Baltic proper. Results indicated a biomagnification of the three most toxic 2378-substituted polychlorinated dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs), whereas the total concentration of 2378- substituted PCDD/Fs, and particularly octachlorodibenzo-p-dioxin and -dibenzofuran (OCDD/F), decreased with increasing trophic level in the food chains. A calculated flux estimate of PCDD/Fs in juvenile eider ducks was supported by results from the biomagnification study; that is, the most toxic 2378-substituted isomers tended to accumulate in the tissue of the eider duck. Out of the total PCDD/Fs consumed by the eider ducks, only 10% were recovered in the body and approximately 10% were recovered in feces, whereas 80% were not recovered, that is, were excreted or remained as unidentified metabolites. Of the most toxic 2378-substituted isomers, 57% were recovered in the tissue, 30% were recovered in the feces, and only 13% were not recovered (i.e., metabolized and/or excreted).
Effects of sediment organic carbon content on the elimination rates of neutral lipophilic compounds in the midge (Chironomus Riparius)
Authors: Lydy Michael J. , Baumann Paul C. , Oris James T. , Fisher Susan W.
Published: March 2010

The effects of varying sediment conditions on elimination rates for four neutral lipophilic compounds were investigated in midge larvae, Chironomus riparius. Four treatments were used: water only (no sediment present) (WO); midges screened from 3% organic carbon (OC) sediment (screened); water and 3% OC sediment (3% OC); and water and 15% OC sediment (15% OC). In general, elimination rates were larger in the 3 and 15% OC sediment systems compared to the WO and screened treatments. The largest elimination rates were found in the 15% OC treatments. The mechanism that accounts for increased elimination rates noted in the high-OC-content sediment systems is unknown; however, several possible mechanisms are discussed. A predictive relationship has been established between the elimination rate constant (Kd), the octanol/water partition coefficient (Kow), and sediment OC content. These results further emphasize the importance of sediment characteristics in determining the environmental fate of xenobiotics.
Glycolysis and krebs cycle metabolites in mosquitofish, Gambusia holbrooki, Girard 1859, exposed to mercuric chloride: Allozyme genotype effects
Authors: Newman Michael C. , Mulvey Margaret , Kramer Vincent J. , Ultsch Gordon R.
Published: March 2010

Concentrations of glycolysis and Krebs (citric acid) cycle metabolites were measured in the tail tissues of mosquitofish (Gambusia holbrooki, Girard 1859) in response to exposure to 0.86 mg/L Hg (as HgCl2) for 28 h. Substrate and product concentrations were compared between allozyme genotypes at two loci (glucosephosphate isomerase-2 and malate dehydrogenase-1) to determine whether allozyme genotypes in mosquitofish were differentially inhibited by mercury. Mercury treatment, regardless of allozyme genotype, caused decreased concentrations of glucose-6-phosphate (-27%) and lactate (-27%). Mercury treatment led to increased concentrations of malate (+33%) and oxaloacetate (+28%). Increased Krebs cycle activity could have been a response to greater energy needs associated with maintaining homeostasis under stressful conditions. There was no evidence of differential inhibition of allozymes at either locus. Fish of genotype Gpi-238/38 exhibited an overall increase in glycolytic activity in response to mercury treatment.
Laboratory spawning of topsmelt, Atherinops affinis, with notes on culture and growth of larvae
Authors: Middaugh D. P. , Hemmer M. J. , Anderson B. S.
Published: March 2010

Topsmelt (Atherinops affinis) were spawned repeatedly in the laboratory from May to July 1989. A periodic “temperature spike” from the holding temperature of approximately 18 up to approximately 20.5°C, introduced at 7- to 9-d intervals, resulted in maximum production of viable embryos on the fourth morning after the spike. Examination of embryonic stages and comparison to known developmental rates for Atherinops affinis embryos revealed that spawning was generally nocturnal, occurring between 1900 and 0500 h. Survival of embryonic and larval Atherinops affinis cultured at 21 ± 1°C and 20 ± 2‰ salinity was excellent (>80%). A larval growth curve was developed for the first 24 d post-hatch.
Effects of fenvalerate on the early life stages of topsmelt (Atherinops Affinis)
Authors: Goodman Larry R. , Hemmer Michael J. , Middaugh Douglas P. , Moore James C.
Published: March 2010

Flow-through acute and early-life-stage (ELS) toxicity tests were conducted with topsmelt (Atherinops affinis), a Pacific coast saltwater fish, and fenvalerate, a synthetic pyrethroid insecticide. The 96-h LC50 for juvenile fish was 0.66 μg/L. In the 30-d ELS test with laboratory-spawned embryos, average measured fenvalerate concentrations were nondetectable (>0.075 μg/L) in two control treatments, 0.14, 0.34, 0.82, 1.5, and 3.2 μg/L. Survival of embryos to hatching ranged from 94 to 100%, with no statistically significant differences among treatments. No fry survived exposure to fenvalerate concentrations ≥0.82 μg/L; overall survival in lower concentrations and control treatments ranged from 86 to 97%. There were no consistent concentration-dependent differences in weight between fish in the carrier-control treatment and fish exposed to fenvalerate. Mean wet weights of surviving fish ranged from 16.9 mg in 0.34 μg/L to 20.3 mg in 0.14 μg/L. The average bioconcentration factor for fish exposed to 0.14 and 0.34 μg fenvalerate per liter was 315.
Variability of community metrics: Detecting changes in structure and function
Authors: Pratt J. R. , Bowers N. J.
Published: March 2010

Increased environmental realism in toxicity testing has been advocated to better predict ecological effects of toxic chemicals, and several aquatic microcosm bioassays have been developed that use both natural and synthetic organism assemblages. Additionally, greater emphasis is being placed on community changes as evidence of adverse effects on aquatic ecosystems. The ability to infer structural or functional changes in stressed vs. unstressed communities is linked to statistical power that arises from the combination of experimental design and the underlying variability in chosen metrics. We evaluated several community response variables (metrics) in aquatic laboratory microcosm experiments and field studies to estimate metric variability. Variability of community metrics under laboratory conditions was similar to that observed in the field. Power curves were constructed to estimate the detectability of significant responses with different experimental designs. Using the median C. V. for each measured response, we estimated the minimum detectable distance for power of 0.8 (β = 0.2) and α = 0.05 for each response. Community metrics with C.V.s <30% allow detection of differences between means of 20 to 60%, using as few as three replicates. Structural metrics such as species richness and standing crop are expected to prove more useful in detecting community and ecosystem changes. Process rates are affected by material supplies that may not change under stress.
Evaluation of community and ecosystem monitoring parameters at a high-elevation, rocky mountain study site
Authors: Bruns D. A. , Wiersma G. B. , Minshall G. W.
Published: March 2010

A multimedia systems approach was used to field test wilderness monitoring guidelines (U.S. Forest Service) at a high elevation site in western Wyoming. Five evaluation criteria having a primary emphasis on an ecosystem conceptual framework were applied to selected ecological parameters (terrestrial and aquatic) that were ranked on a relative scoring basis. The ecosystem conceptual criterion was based on the general attributes of the subalpine system, the nature of the potential environmental problem (acidic deposition), and ecological resources at risk. The other criteria were data variability, uncertainty, usability of methods, and cost-effectiveness. Data on sulfate deposition and buffering capacity of soils and surface waters relative to an elevational gradient supported the notion of greater risk to ecological resources in the subalpine environment. Within this ecosystem perspective, litter decay and taxonomic richness of lotic macroinvertebrates had the highest rating, followed by lotic functional feeding groups and lignin-to-nitrogen ratios. A biotic index for stream macroinvertebrates received the lowest rating on an ecosystem conceptual basis and also scored low on the uncertainty and cost-effectiveness criteria; however, suggestions were made for future improvement. Most parameters were similar in regard to variability and usability, except for functional groups, which exhibited greater data variability.
An evaluation of a genotoxicity assay with liver s9 for activation and luminescent bacteria for detection
Authors: Thomas Johnson B.
Published: March 2010

A new short-term in vitro genotoxicity assay with marine bioluminescent bacteria was evaluated for sensitivity and cost. Known under the trade name of Mutatox™, this assay is a simple and rapid screening tool that detects DNA-damaging substances (genotoxins) by measuring light output from an isolated dark mutant strain of the luminescent bacterium Photobacterium phosphoreum. A positive response indicates the ability of the test chemical to restore the luminescent state in the dark mutant strain; the degree of light increase indicates the relative genotoxicity of the sample. In this study, the Mutatox assay with rat hepatic fractions (S9) as an exogenous metabolic activation system detected genotoxic activity with known progenotoxins: 2-acetamidofluorene, aflatoxin B1, 2-aminoanthracene, 2-aminofluorene, 2-aminonaphthalene, benzo[a]pyrene, 3-methyl-cholanthrene, and pyrene. Each chemical clearly demonstrated a dose response between 5.0 and 0.6 μg per tube. Known nongenotoxic controls carbofuran, di-2-ethylhexyl phthalate, malathion, simazine, and permethrin showed no genotoxic responses. The optimum assay conditions were determined to be rat S9 concentration of 0.4 mg/ml, preincubation at 37°C for 30 min, and 18 h incubation at 23°C. Genotoxicity data were obtained in <24 h. The Mutatox assay compared favorably in sensitivity with the Ames test; it was easier and more rapid to perform and, as a result, cost less. The sensitivity, specificity, and predictive value suggested that the Mutatox assay could be a valuable screening tool to monitor complex environmental samples for genotoxins.
The use of freshwater and saltwater animals to distinguish between the toxic effects of salinity and contaminants in irrigation drain water
Authors: Ingersoll C. G. , Dwyer F. J. , Burch S. A. , Nelson M. K. , Buckler D. R. , Hunn J. B.
Published: March 2010

Irrigation drain waters entering Stillwater Wildlife Management Area (SWMA) in south-western Nevada contain elevated levels of salinity and several inorganic contaminants (As, B, Cu, Li, Mo, and Sr). Mortalities of fish and waterfowl at the management area are believed to be associated with the poor water quality of the drains. The objective of the present study was to use fresh-water and saltwater animals to distinguish between the toxic effects of salinity and contaminants in effluent samples collected from irrigation drain waters. Static acute effluent tests were conducted with water collected from four sites at SWMA. Animals acclimated or cultured in fresh water (fathead minnows, Pimephales promelas; amphipods, Hyalella azteca; cladocerans, Daphnia magna) and salt water (striped bass, Morone saxatilis; amphipods, Hyalella azteca; and cladocerans, Daphnia magna) were used to separate toxic effects of salinity from the effects of inorganic contaminants in the drain water. One drain water (TJ drain, salinity 19 parts per thousand (grams per liter), osmolality 503 mmol/kg, hardness 3,780 mg/L as CaCO3) was toxic only to freshwater animals and saltwater cultured daphnids; water from a receiving pond (Pintail Bay, salinity 23 g/L, osmolality 542 mmol/kg, hardness 830 mg/L as CaCO3) was toxic to both freshwater and saltwater animals. Acute tests conducted with reconstituted waters representative of the Pintail Bay sample indicated that atypical ion ratios were toxic to striped bass and amphipods, even without the addition of inorganic contaminants. However, the addition of inorganic contaminants representative of the Pintail Bay sample increased the toxicity of this reconstituted water. These findings indicate that the toxicity of the TJ drain sample was related mainly to elevated salinity and that the toxicity of the Pintail Bay sample was a function of inorganic contamination and atypical ion ratios in combination with elevated salinity.
Influence of the addition of cerophyl® on theSelenastrum capricornutumdiet of the cladoceranCeriodaphnia dubia
Authors: Knight John T. , Waller William T.
Published: March 2010

A study of the green alga Selenastrum capricornutum and Cerophyl® was conducted to characterize the mixture as food for Ceriodaphnia dubia. The addition of an aqueous extract of Cerophyl to Selenastrum capricornutum resulted in consistently greater survival, growth, and productivity of Ceriodaphnia dubia cultured and tested in reconstituted hard water. Several supplemental foods, including yeast-Cerophyl-Trout Chow® (YCT), were tested with, or in addition to, Selenastrum capricornutum. Analysis of the protein, carbohydrate, and lipid content of the algae-plus-Cerophyl feeding suspension indicated that the addition of the aqueous extract of Cerophyl increased the protein concentration of the feeding suspension 30% and the carbohydrate concentration 50%. The amount of lipid contained in the Cerophyl extract was less than the detection limit of the method used for analysis. Treatment of the aqueous extract of Cerophyl for the removal of the protein and lipid components of the Cerophyl had no effect on the growth and productivity of Ceriodaphnia dubia when compared to those of the organisms fed an unaltered mixture of algae plus Cerophyl. The bacteria associated with the Selenastrum capricornutum cultures, the algae-plus-Cerophyl feeding suspension, the Ceriodaphnia dubia mass cultures, and the individual beakers in which isolated Ceriodaphnia dubia was tested were enumerated. The bacteria associated with the algae-Cerophyl feeding suspension were shown to play a role in the diet of Ceriodaphnia dubia during the first 4 to 5 d of 7-day tests. However, substituting bacteria for Cerophyl in the algal feeding suspension fed to Ceriodaphnia dubia did not result in the same level of survival, growth, and productivity.
Factors affecting the bioconcentration of hexachlorocyclohexanes in early life stages of Oncorhynchus mykiss
Authors: Viganò L. , Galassi S. , Gatto M.
Published: March 2010

A commercial mixture of α-, β-, γ-, and δ-hexachlorocyclohexane (-HCH) isomers has been tested for bioconcentration on early life stages of Oncorhynchus mykiss. Experimental results were elaborated by means of BIOCON, an interactive program for personal computers that provides bioconcentration factors (BCFs) and kinetic uptake and depuration coefficients as well as their standard deviations. The comparisons performed on a statistical basis evidenced few differences among the bioconcentration capability of larval stages, contrary to what was observed in previous studies with other chemicals. In the early juvenile stage, α- and δ-HCH are characterized by higher BCFs than the γ-isomer. The role of lipids is also investigated. The total lipid content seems to play a major role in influencing bioaccumulation parameters but cannot thoroughly explain BCF variability, which must be ascribed to other factors such as life stage and lipid composition.
Effect of organic carbon on the uptake and toxicity of quaternary ammonium compounds to the fathead minnow, Pimephales promelas
Authors: Versteeg Donald J. , Shorter Shirley J
Published: March 2010

The effect of dissolved organic, carbon on the uptake and toxicity of quaternary ammonium compounds was investigated with the fathead minnow, Pinephales promelas Aldrich humic acid (HA) reduced the toxicity of dioctadccyl dimethyl ammonium chloride (DODMAC) and monotallow trimethyl ammonium chloride (C1c  1gTMAC) but had no effect on the toxicity of tetradecyl trimethyl ammonium chloride (CgTMAC) dodecyl trimethyl ammonium chloride (C12, TMAC) or of octyl trimethyl ammonium chloride (CbTMAC) Aldrich HA also reduced the uptake rate constant of DODMAC and C16  12TMAC For DODMAC, the reduction in toxicity observed by Aldrich HA was similar to those observed with Suwannee River and Nordic Aquatic HAs and organic carbon from two river waters For C1c  1gTMAC Suwannee River and Nordic Aquatic HAs and river water organic carbon caused a significant amelioration of toxicity This amchoration of toxicity was quantitatively less than predicted based on Aldrich HA
An equilibrium model of organic chemical accumulation in aquatic food webs with sediment interaction
Authors: Thomann Robert V. , Connolly John P. , Parkerton Thomas F.
Published: March 2010

A five-compartment steady-state food-web model is constructed that includes a benthic invertebrate compartment Four exposure routes are considered in the description of accumulation by benthic animals ingestion of particulate contaminants associated with (a) sediment organic carbon and (b) overlying phytoplankton and ventilation of free dissolved contaminant in (c) interstitial and (d) overlying water Normalization of organism lipid-based chemical concentration to sediment organic carbon (the biota sediment factor, BSF) or to overlying water concentration (the bioaccumulation factor, BAF) indicates the significance of the sediment/overlying water partition coefficient for systems that have a benthic component The impact of the benthic component on a forage fish is related directly to this partitioning Application of the model to an amphipod-scul pin web for Lake Ontario indicates (a) amphipod water exposure is a combination of interstitial and overlying water concentrations, (b) amphipod feeding appears to be a combination of overlying phy toplankton and sediment organic carbon, (c) amphipod and sculpin chemical assimilation efficiency appears to be a complicated function of octanol-water partition coefficient, (d) observed BAF for amphipod and sculpin is about one order of magnitude higher than log Kow in the range 5 5 to 7 0 and is calculated to be due almost entirely to food-web transfer from the sediment, as opposed to uptake from the water route
Uncertainty and sediment quality assessments: II. Effects of correlations between contaminants on the interpretation of apparent effects threshold data
Authors: Alden Raymond W. , Rule Joseph H.
Published: March 2010

The apparent effects threshold (AET) is an approach being considered for the establishment of sediment quality criteria The AET is the empirically determined concentration of a contaminant in sediments above which adverse biological effects have been observed consistently However, previous investigators have suggested that correlation among contaminants may limit the applicability of the AET approach The present study employed empirically based simulations to examine the effects of correlation among contaminants on the validity of AETs as ecologically de fensible sediment quality criteria The simulations indicated that moderately high correlations (r > 0 6) between contaminants produced a high probability of setting invalid AETs Slightly higher correlations (r > 0 7) produced invalid AETs that could not be detected as being “false,” even with large sampling efforts (n = 300) False AETs also were observed to be frequently encountered for more modest sampling regimes (n = 50) when correlations among contaminants were high (r > 0 7)

It is clear that AETs can serve as indicators/surrogates for toxicants in sediments of the region in which they are established However, considering the confounding effects of correlations between contaminants, both measured and unmeasured, it is recommended that regulatory sediment quality assessments be based on site-specific toxicological investigations rather than generic AET based criteria or standards Any AET based criteria should be considered “first cut” levels of concern for identifying areas that display heavy sediment contaminant loads Regulatory actions based on AET criteria should be implemented only if these values have been validated by independent toxicological investigations