bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioaccumulation of dietary 2,2′,4,4′,5,5′-hexachlorobiphenyl and induction of hepatic arylhydrocarbon hydroxylase in rainbow trout (Oncorhynchus mykiss)
Authors: da Costa Emmanuel G. , Curtis Lawrence R.
Published: March 2010

Juvenile rainbow trout (Oncorhynchus mykiss) were fed either 5 or 20 μg 2,2′,4,4′,5,5′-hexachlorobiphenyl (245-HxCB)/g diet (wet wt.) for 4, 8, or 12 weeks. Hepatic xenobiotic-metabolizing enzyme activities and dietary 245-HxCB accumulation in liver, muscle, and remaining carcass were determined. Liver-to-body weight ratios were not altered by either of the two 245-HxCB concentrations. Relative growth rate increased with time but was not altered by 245-HxCB concentration. Bioaccumulation of 245-HxCB was dose and time dependent in all tissues without reaching apparent steady state. Hepatic arylhydrocarbon hydroxylase (AHH) activities increased with 245-HxCB dose and with time. Ethoxyresorufin-O-deethylase (EROD) activities also increased in fish fed 20 μg 245-HxCB/g diet. No 245-HxCB-induced changes in uridine diphosphoglucuronosyl transferase (UDP-GT) or NADPH-cytochrome-c reductase (NCCR) activities were determined. High-resolution GC-MS analysis of the 245-HxCB standard revealed trace (0.4-0.5%) contamination by two mono-ortho pentachlorobiphenyls (PnCBs): 2,3,3′,4,4′-PnCB and 2,3,4,4′,5-PnCB. Total liver accumulation of these contaminants was inversely related with corresponding EROD and AHH activities and estimated to contribute minimally to their induction. Results from this study suggested that long-term dietary 245-HxCB exposures induced cytochrome P4501A activities in rainbow trout liver.
Fathead minnow reproduction in outdoor microcosms: A comparison to bluegill sunfish reproduction in large mesocosms
Authors: Shaw Jennifer L. , Maund Stephen J. , Hill Ian R.
Published: March 2010

Large-scale aquatic mesocosm studies were formerly required by the U.S. Environmental Protection Agency (EPA) for ecological risk assessment in pesticide registration. However, the use of bluegill sunfish (Lepomis macrochirus Rafinesque) to evaluate pesticide effects on fish reproduction in large mesocosms (>300 m3) resulted in over-exploitation of invertebrates by large numbers of young-of-the-year (YOY) bluegill, thus confounding the interpretation of pesticide effects. As an alternative, a reproduction study with fathead minnows (Pimephales promelas Rafinesque) was conducted in 17-m3 outdoor microcosms. The objective of this research was to evaluate the effects of varying sex ratios of 20 adult fathead minnows (FHMs) on their reproduction during a 4.5-month period. The outcome of this study was compared to a bluegill reproduction study in 400-m3 mesocosms conducted synchronously. The logistics of monitoring the microcosms were simpler, and harvesting FHMs from microcosms took considerably less effort in comparison to harvesting bluegills from mesocosms. The FHMs produced a smaller number of larger young in comparison to bluegills, which produced large numbers of less mature YOY. The variability in total fish biomass between replicates was greater in the bluegill study, resulting in less statistical power to detect biomass effects. The FHM sex ratios significantly affected reproduction and growth, thus altering the fish population structure, despite similar stocking densities. Sex ratios with similar numbers of males and females produced a lower total biomass and number of YOY. There was no evidence of system carrying-capacity constraints on FHM growth or reproduction.
Use of coded wire tags to identify fathead minnow (Pimephales promelas rafinesque) adults in an outdoor microcosm study designed to evaluate consistency in reproduction
Authors: Shaw Jennifer L. , Copeland John R. , Johnson J. Keith
Published: March 2010

Fathead minnows (Pimephales promelas) were evaluated for use as a test species in ecosystem-level studies investigating pesticide effects on fish reproduction. Twenty adult fathead minnows (8 females: 12 males) were stocked in four, 17-m3 outdoor microcosms and collected 98 d later. Each fish was identified with a coded wire tag (CWT). In a preliminary indoor experiment, survival was 100% and tag retention was 93%, 33 d after tagging. At the end of the field study, 100% of surviving stocked adults had tags in three of the four replicates. In these microcosms, stocked adults could be differentiated from young-of-the-year (YOY) because there was no size overlap of YOY with the larger stocked adults, whereas in the fourth replicate the YOY grew to maturity. Fathead minnow reproduction was compared to a study conducted the preceding season utilizing the same experimental systems and incorporating the same 8F:12M sex ratio at stocking. Reproduction was consistent for identical sex ratios in the different seasons despite differences in water conditions. In both years, fathead minnow fecundity was similar, and fish size distributions had equivalent attributes. Furthermore, the relationship between fish number and biomass was comparable, and regressions of weight on length were equal.
Long-term fate and bioavailability of sediment-associated polychlorinated dibenzo-p-dioxins in aquatic mesocosms
Authors: Segstro Mark D. , Muir Derek C.G. , Servos Mark R. , Webster G.R. Barrie
Published: March 2010

The long-term fate of four polychlorinated dibenzo-p-dioxin (PCDD) congeners in sediments and their bioavailability to benthic invertebrates were studied in littoral enclosures located in a small lake at the Experimental Lakes Area in northwestern Ontario. The PCDDs sorbed on sediment particles were added to the 5-m-diameter enclosures on June 12, 1985, and concentrations in sediment cores (0 to 6 cm) were determined over 1,800-d (˜ 5 years). Concentrations of 1,3,6,8-TCDD, 1,3,7,9-TCDD, HpCDD, and OCDD in the sediment declined, with half-lives of 4.4±1.7, 4.6±1.9, 6.2±3.1, and 6.0±2.8 year, respectively. Evaluation of the data for 1,3,6,8-TCDD and OCDD using a sediment-water exchange model suggested that the decline in PCDD concentrations was due to losses to the water column via diffusion of DOC-associated PCDDs in pore water and via particle resuspension. After 5 years the PCDDs remained bioavailable to freshwater mussel (Anodonta grandis) and crayfish (Orconectes virilis) exposed to sediments for up to 78 d. The crayfish had higher mean biota-sediment accumulation factors (BSAFs) for 1,3,6,8-TCDD and 1,3,7,9-TCDD (0.31–0.53) than did mussels (0.07–0.13), whereas BSAFs for HpCDD and OCDD in the two species were similar (0.03–0.09).
Toxicity and bioaccumulation of sediment-associated contaminants using freshwater invertebrates: A review of methods and applications
Authors: Ingersoll Christopher G. , Brunson Eric L. , Dwyer F. James , Ankley Gerald T. , Benoit Duane A. , Norberg-King Teresa J. , Burton G. Allen , Hoke Robert A. , Landrum Peter F. , Winger Parley V.
Published: March 2010

This paper reviews recent developments in methods for evaluating the toxicity and bioaccumulation of contaminants associated with freshwater sediments and summarizes example case studies demonstrating the application of these methods. Over the past decade, research has emphasized development of more specific testing procedures for conducting 10-d toxicity tests with the amphipod Hyalella azteca and the midge Chironomus tentans. Toxicity endpoints measured in these tests are survival for H. azteca and survival and growth for C. tentans. Guidance has also been developed for conducting 28-d bioaccumulation tests with the oligochaete Lumbriculus variegatus, including determination of bioaccumulation kinetics for different compound classes. These methods have been applied to a variety of sediments to address issues ranging from site assessments to bioavailability of organic and inorganic contaminants using field-collected and laboratory-spiked samples. Survival and growth of controls routinely meet or exceed test acceptability criteria. Results of laboratory bioaccumulation studies with L. variegatus have been confirmed with comparisons to residues (PCBs, PAHs, DDT) present from synoptically collected field populations of oligochaetes. Additional method development is currently underway to develop chronic toxicity tests and to provide additional data-confirming responses observed in laboratory sediment tests with natural benthic populations.
Acute and subchronic toxicity of naturally weathered Exxon valdez crude oil in mallards and ferrets
Authors: Stubblefield William A. , Hancock Gregg A. , Ford William H. , Ringer Robert K.
Published: March 2010

The toxic properties of naturally weathered Exxon Valdez crude oil (WEVC) were assessed in a battery of acute and subchronic toxicity tests using mallards, Anas platyrhynchos, and European ferrets, Mustela putorius. Adult mallard acute oral toxicity study results indicated no mortalities or signs of toxicity, i.e., no-observed-adverse-effect level (NOAEL) and median lethal dose (LD50) > 5,000 mg/kg. Acute oral feeding and food avoidance tests with ducklings also indicated no toxicity (NOAEL and LC50 > 50,000 mg/kg diet) with no evidence of food avoidance (FAC50 > 20,000 mg/kg diet). No mortalities or toxic signs were noted in a 14-d feeding study with adult birds at dietary concentrations up to 100,000 mg WEVC/kg diet. Among clinical and physiological end points evaluated, the only significant difference noted was an increase in liver:body weight ratios in the 100,000-mg WEVC/kg diet dose group. No differences in clinical chemistry or hematological parameters were noted, and there were no consistent differences in histological evaluations of organ tissues. Daily oral doses of up to 5,000 mg/kg of WEVC over 5 d resulted in minimal effects on ferrets. Increased serum albumin concentrations were observed in the 5,000-mg/kg dose group females and decreased spleen weights were noted in females of all WEVC treatment groups. No other significant observations were noted.
Chronic toxicity of 14 phthalate esters toDaphnia magnaand rainbow trout (Oncorhynchus mykiss)
Authors: Rhodes Jon E. , Adams William J. , Biddinger Gregory R. , Robillard Kenneth A. , Gorsuch Joseph W.
Published: March 2010

Chronic toxicity studies were performed with commercial phthalate esters and Daphnia magna (14 phthalates) and rainbow trout (Oncorhynchus mykiss) (six phthalates). For the lower-molecular-weight phthalate esters–dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and butylbenzyl phthalate (BBP)–the results of the studies indicated a general trend in which toxicity for both species increased as water solubility decreased. The geometric mean maximum acceptable toxicant concentration (GM-MATC) for D. magna ranged from 0.63 to 34.8 mg/L. For the higher-molecular-weight phthalate esters–dihexyl phthalate (DHP), butyl 2-ethylhexyl phthalate (BOP), di-(n-hexyl, n-octyl, n-decyl) phthalate (610P), di-(2-ethylhexyl) phthalate (DEHP), diisooctyl phthalate (DIOP), diisononyl phthalate (DINP), di-(heptyl, nonyl, undecyl) phthalate (711P), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), and ditridecyl phthalate (DTDP)-the GM-MATC values ranged from 0.042 to 0.15 mg/L. Survival was equally sensitive and sometimes more sensitive than reproduction. The observed toxicity to daphnids with most of the higher-molecular-weight phthalate esters appeared to be due to surface entrapment or a mode of toxicity that is not due to exposure to dissolved aqueous-phase chemical. Early life-stage toxicity studies with rainbow trout indicated that survival (DMP) and growth (DBP) were affected at 24 and 0.19 mg/L, respectively. This pattern of observed toxicity with the lower-molecular-weight phthalate esters and not the higher-molecular-weight phthalate esters is consistent with previously reported acute toxicity studies for several aquatic species.
ΣPAH: A Model to predict the toxicity of polynuclear aromatic hydrocarbon mixtures in field-collected sediments
Authors: Swartz Richard C. , Schults Donald W. , Ozretich Robert J. , Lamberson Janet O. , Cole Faith A. , Ferraro Steven P. , Dewitt Theodore H. , Redmond Michele S.
Published: March 2010

The ΣPAH model estimates the probability of toxicity of PAH-contaminated sediments using a combination of equilibrium partitioning, QSAR, toxic unit, additivity, and concentration-response models. The sediment concentration of organic carbon and 13 PAH (polynuclear aromatic hydrocarbon) compounds were measured. Interstitial water concentrations (PAH1W) of the 13 compounds were predicted by equilibrium partitioning. The 10-d LC50 of each compound in interstitial water (10-d LC501W) was predicted by a QSAR regression of 10-d LC501W (from spiked sediment tests) to Kow. Toxic unit concentrations of individual compounds (TU1) were predicted as PAH1w/10-d LC501w. The total number of toxic units of the 13 compounds (ΣTU1) was calculated assuming the additivity of toxic effects of PAHs. ΣTU1 was used to predict the probability of toxicity to marine and estuarine amphipods using a concentration-response model derived from spiked sediment toxicity tests. The ΣPAH model was verified by comparing predicted and observed toxicity in field-collected sediment samples. There was 86.6% correspondence and no significant difference between predicted and observed toxicity at PAH-contaminated sites. Ecological-effect levels predicted by theΣPAH model correspond with several sediment-quality guidelines.
Prediction of adsorption of divalent heavy metals at the goethite/water interface by surface complexation modeling
Authors: Kooner Zorawar S. , Cox Chris D. , Smoot James L.
Published: March 2010

The triple-layer model was used to model the adsorption behavior of Cu(II), Pb(II), and Zn(II) onto goethite as a function of pH, total dissolved metal (Me) concentration, surface area, and ionic strength. A single reaction involving adsorption of Me2+ onto negative surface sites as an inner-sphere complex proved successful in describing adsorption of all three metals under the experimental conditions. The calibrated model was validated by comparing model predictions to independent data reported in the literature. A linear-free-energy relationship between the intrinsic surface complexation and the first-hydrolysis equilibrium constants was determined and was used to predict the intrinsic surface complexation constants for Co(II) and Hg(II). The triple-layer model, using the predicted constants, quantitatively described the adsorption of Co(II), but significantly over-predicted the extent of Hg(II) adsorption.
Comparison of the 10-day freshwater sediment toxicity tests usingHyalella AztecaandChironomus Tentans
Authors: Becker Scott D. , Bigham Gary N. , Rose Curt D.
Published: March 2010

Comparisons were made of the performance of the 10-d fresh water sediment toxicity tests using the amphipod Hyalella azteca and midge Chironomus tentans. Sediments were collected from eight stations in Onondaga Lake, New York, and represented a wide range of toxicity. The biological end points were survival, biomass, and body length. The two tests were compared on the basis of correspondence among relative values of the end points and ability to statistically discriminate adverse effects relative to control responses (i.e., discriminatory ability). Minimum detectable differences (MDDs) and adverse response ranges of the end points were used to further evaluate the discriminatory ability of the end points. Relative responses and discriminatory abilities of the end points of both tests were similar, despite numerous differences that exist among characteristics of the test species and end points. Significant concordance was found among all end points with respect to relative toxicity of sediments from the eight stations. Although MDDs and adverse response ranges of the various end points differed substantially, the observed positive correlation between those two variables resulted in all end points having similar discriminatory ability. Although amphipod biomass and body length have rarely been used as end points in 10-d tests, both end points provided results comparable to those of the other end points evaluated in the present study.
Reduction of the explosive 2,4,6-trinitrotoluene by enzymes from aquatic sediments
Authors: Van Beelen Patrick , Burris David R.
Published: March 2010

Enzymes were extracted from aquatic sediments. Some of these enzymes reduced 2,4,6-trinitrotoluene (TNT) with nicotinamide adenosine dinucleotide phosphate (NADPH) as an electron donor under aerobic conditions. The origin of these enzymes was not clear as the enzymes were extracted from a sediment containing plant roots and microorganisms. Aquatic plants were determined to be a source of TNT-reducing enzymes. Chemical reduction was not a rate-limiting process in the assays as the enzymatic activity was inhibited by heating or the addition of proteases. Enzymatic activity in the extracts was further characterized. Partial purifications of enzymes from the sediment extracts shows that several proteins capable of reducing TNT with NADPH were present. The enzymes did not require flavins and preferred NADPH over NADH as the electron donor. The pH optimum for the stability of the enzymes was near neutral, and the temperature optimum was in the 37 to 45°C range. Addition of dithiothreitol improved the stability of the enzymes. The enzymes reduced 2,4,6-trinitrotoluene to 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, and 2,6-diamino-4-nitrotoluene under aerobic conditions with NADPH. When used as a starting substrate, the aminodinitrotoluenes were not reduced by the enzymes. It might be possible that the hydroxylaminodinitrotoluenes are reduced to di[hydroxylamine]nitrotoluenes prior to the formation of the diamino-nitrotoluenes. Sediments from 11 surface water bodies were examined for the presence of TNT-reducing enzymes, and 10 were found to have activity. These enzymes appear to be ubiquitous and are present in both freshwater and saltwater sediments. Reduction of TNT by sediment enzymes can be a significant environmental fate process for TNT in aquatic systems.
Avian plasma carboxylesterase activity as a potential biomarker of organophosphate pesticide exposure
Authors: Bartkowiak Donna J. , Wilson Barry W.
Published: March 2010

Plasma cholinesterase (ChE) and carboxylesterase (CaE) activities were measured in pigeons (Columba hvia), captive and wild American kestrels (Falco sparveius), red-tailed hawks (Buteo jamaicensis), Swainson's hawks (Buteo swainsoni), Cooper's hawks (Accipiter cooperit), and red-shouldered hawks (Buteo lineatus). The effect of organophosphate (OP) insecticides on pigeon ChE and CaE activities was determined. Pigeon plasma CaE activity showed distinct groups averaging 12.4 and 138 nmol/min/ml plasma. The CaE activity for raptors was less than 20 nmol/min/ml plasma. Both ChE and CaE activities were inhibited by 0.4 mg/kg ethyl parathion, but CaE activity was not inhibited by 10 mg/kg methidathion. There was no difference in the blood ChE activities of pigeons with low or high blood CaE after treatment with parathion. In general, CaE activity was less severely depressed and recovery was less predictable than was ChE activity.
An ecological risk assessment of lead shot exposure in non-waterfowl avian species: Upland game birds and raptors
Authors: Kendall Ronald J. , Lacker Thomas E. , Bunck Christine , Daniel Bernard , Driver Crystal , Grue Christian E. , Leighton Frederick , Stansley William , Watanabe Philip G. , Whitworth Molly
Published: March 2010

There is increasing concern that birds in terrestrial ecosystems may be exposed to spent lead shot. Evidence exists that upland birds, particularly mourning doves (Zenaida macroura), ingest spent lead shot and that raptors ingest lead shot by consuming wounded game. Mortality, neurological dysfunction, immune suppression, and reproductive impairment are documented effects of exposure to lead in birds. An ecological risk assessment on the impact of lead shot exposure in upland birds was conducted and is presented in the context of the new United States Environmental Protection Agency's Ecological Risk Assessment Paradigm. A considerable amount of spent lead shot is released into the environment each year from shooting and hunting. Doves collected from fields that are cultivated to attract mourning doves for hunting activities show evidence of ingestion of spent lead shot. Because lead can cause both acute and chronic toxicity if ingested by birds, and because there is evidence of widespread deposition of lead shot in terrestrial ecosystems, concern for impacts on upland game birds and raptors seems warranted. Although this ecological risk assessment does not clearly define a significant risk of lead shot exposure to upland game birds, this issue merits continued scrutiny to protect our upland game bird and raptor resources.
Preliminary study to compare body residues and sublethal energetic responses in benthic invertebrates exposed to sediment-bound 2,4,5-trichlorophenol
Authors: Penttinen Olli-Pekka , Kukkonen Jussi , Pellinen Jukka
Published: March 2010

Relationships between concentration of 2,4,5-trichlorophenol (TCP) in sediment, body residues of the chemical, and sublethal biological effects in three benthic invertebrates were studied. Uncontaminated lake sediment was spiked with four concentrations (23–85 μg/g dry sediment) of TCP. Chironomid larvae (Chironomus riparius), oligochaete worms (Lumbriculus variegatus), and sphaeriid bivalves (Sphaerium corneum) were exposed to the sediment. The effect of chlorophenol on the rate of heat dissipation of animals was monitored by direct microcalorimetry. It appeared that both the behavior of the animals and their body residues explained the energetic response. Valve closure behavior of S. corneum reduced the accumulation of toxicant (<0.3 μmol/g) but was observed as a complex energetic response. Heat dissipation of L. variegatus was at the same level in control animals and those with high body residues of TCP (>1.5 μmol/g). Regardless of the amount of TCP accumulated to C. riparius (0.1–0.6 μmol/g), the rate of heat dissipation was almost two times higher than that of the control animals, probably reflecting uncoupling of oxidative phosphorylation, which is the primary mode of toxic action of chlorophenols. However, when a threshold concentration was exceeded there was no concentration-response dependence until acute toxicity appears.
Inhibition of testicular growth in rainbow trout (Oncorhynchus mykiss) exposed to estrogenic alkylphenolic chemicals
Authors: Jobling Susan , Sumpter John P. , Sheahan David , Osborne Julia A. , Matthiessen Peter
Published: March 2010

It is becoming evident that an increasing number of widely used industrial and agricultural chemicals are estrogenic. The biodegradation products of a major group of nonionic surfactants, the alkylphenol polyethoxylates, are one such group. Some of these chemicals are widespread aquatic pollutants, and bioconcentrate in aquatic biota. Exposure of male rainbow trout (Oncorhynchus mykiss) to four different alkylphenolic chemicals caused synthesis of vitellogenin, a process normally dependent on endogenous estrogens, and a concomitant inhibition of testicular growth. The magnitude of these estrogenic effects was dependent on the estrogenic potency of the chemical, the stage of reproductive development of the fish, and the concentration of the chemical in the water. These results support the contention that exposure of wildlife to environmentally persistent estrogenic chemicals can result in deleterious reproductive consequences.
Toxic potencies of lipophilic extracts from sediments and settling particulate matter (SPM) collected in a PCB-contaminated river system
Authors: Engwall Magnus , Broman Dag , Brunström Björn , Ishaq Rasha , Näf Carina , Zebühr Yngve
Published: March 2010

Sediments and settling particulate matter (SPM) were sampled in a polychlorinated biphenyl (PCB)-contaminated lake, Lake Järnsjön, and in lakes located up-/and downstream from Lake Järnsjön. The 7-ethoxyresorufin O-deethylase (EROD)-inducing potencies of lipophilic extracts from sediment and SPM were investigated in organ cultures of chicken embryo livers (denoted in vitro chicken embryo liver bioassay). The extract from sediments collected in Lake Järnsjön had the greatest EROD-inducing potency of the extracts studied, and it also contained the highest concentrations of PCBs, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dibenzodioxins/furans (PCDDs/Fs). The non-ortho-chlorinated PCBs in the extracts were probably major contributors to the EROD induction noted. The EROD-inducing potency of sediment extract from the lake downstream Lake Järnsjön was higher than that of extract from the upstream lake. This indicates that EROD-inducing substances were transported from Lake Järnsjön sediment to the lake downstream. The extracts from Lake Järnsjön sediment and SPM were separated into three fractions containing aliphatic/monoaromatic, diaromatic, and polyaromatic compounds, respectively, which were tested in the in vitro chicken embryo liver bioassay. In all extracts, the aliphatic/monoaromatic fractions were low in EROD-inducing potency, while the polyaromatic fractions from SPM were more potent than their corresponding diaromatic fractions, indicating that they contained high concentrations of aromatic hydrocarbon (Ah) receptor ligands. Only a small part of the EROD induction caused by the polyaromatic fractions could be attributed to the 15 analyzed PAHs in the samples. The EROD-inducing potencies of the diaromatic fractions correlated quite well with their concentrations of PCDDs/Fs and PCBs. The in vitro chicken embryo liver bioassay detected low concentrations of EROD inducers in the extracts and therefore proved useful for estimating the contents of Ah receptor ligands in environmental samples.
Environmental chemistry for a surfactant ecotoxicology study supports rapid degradation of C12-alkyl sulfate in a continuous-flow stream Mesocosm
Authors: Guckert James B. , Walker David D. , Belanger Scott E.
Published: March 2010

Environmental chemistry is a vital part of ecotoxicology studies conducted in mesocosms. Quantification of exposure can be particularly challenging for biodegradable surfactants in once-through stream mesocosms like the Procter & Gamble Experimental Stream Facility (ESF). In the fall of 1991, a study was conducted with the anionic surfactant C12-alkyl sulfate (C12-AS). Analysis of chemical feed tank concentrates indicated that the in-stream concentrations should be very close to the nominal concentrations (26, 78, 233, 700, 2, 100 μg/L). However, measured concentrations were lower than expected. The concentrations at the head of the streams were 4 to 23% below nominal concentrations and there was an additional 14 to 33% decline in head to tail C12-AS concentrations. Total residence time in the streams is about 4.3 min. Because analytical losses had been minimized using individual sample recovery factors, it was concluded that these losses were due to rapid C12-AS biodegradation. The results of this analytical program are used to define the in-stream C12-AS concentrations to express subsequent community- and ecosystem-level no-observed-effect concentrations. In addition, the environmental chemistry program described will serve as the model for future programs in support of surfactant ecotoxicology studies conducted at the ESF.
Fish bioturbation of cadmium-contaminated sediments: Factors affecting Cd availability to Daphnia magna
Authors: Wall Steven B. , La Point Thomas W. , Isely J. Jeffrey
Published: March 2010

Benthic fish bioturbation of contaminated sediments is thought to enhance exposure and, potentially, bioaccumulation into planktonic organisms. Exposures were conducted with cadmium-spiked sediment, 1.0 mg/kg nominal concentrations, and koi carp (Cyprinus carpio). Daphnia magna were placed in aquaria with and without fish for 6 d and Cd bioaccumulation was measured every 48 h. Koi carp bioturbation increased mean total suspended solids (TSS) in two trials from 0.001 mg/L to 44.4 mg/L and 19.2 mg/L to 762.4 mg/L. Mean aqueous Cd concentrations increased from 1.4 μg/L to 2.8 μg/L, and from 1.6 μg/L to 13.2 μg/L. Cadmium binding capacity increased from 28.9 μg/L to 169.8 μg/L in with-fish treatments when compared to controls. However, Daphnia magna body burdens did not increase. Mean Cd residues of daphnids exposed with fish, 9.2 μg/g, were not statistically different from without-fish exposures, 8.0 μg/g. Body burdens slightly decreased in the first trial after the with-fish treatment, 9.4 μg/g to 8.3 μg/g. Fish size was partially correlated with TSS and aqueous Cd concentrations and TSS positively correlated with binding capacity. Because increased TSS in the with-fish treatment resulted in increased binding capacity, it is probable that cadmium bioavailability decreased. Although koi carp were capable of remobilizing Cd from sediment, Cd bioaccumulation into Daphnia magna was not significant.
Profile of toxic response to sediments using whole-animal and in vitro submitochondrial particle (SMP) assays
Authors: Bettermann Alan D. , Dorofi Jonathan C. , Lazorchak James M.
Published: March 2010

A rapid bioassay for monitoring acute toxicity of wastewater, ground water, and soil and sediment extracts using submitochondrial particles (SMP) has been developed. The assay utilizes the mitochondrial electron transfer enzyme complex, present in all eukaryotic cells. Prior developmental work with pure chemicals chosen from the U.S. Environmental Protection Agency's (EPA) priority pollutant list documented order-of-magnitude predictability between the bioassay response and whole-organism tests (e.g., fathead minnow). Recent work has adapted the assay for analysis of uncharacterized environmental samples, including stormwater runoff, landfill leachate, and soil and sediment extracts. A feasibility study was performed to determine whether the SMP assay could detect toxicity in samples previously assessed for toxicity to amphipods. Acute toxicity tests using Hyalella azteca were performed on 30 sediment samples from Colorado's Arkansas River, Eagle River, and Chalk Creek watersheds, all of which have been directly or indirectly affected by heavy metal mine tailings and drainage. In parallel, two SMP assay protocols designed to differentiate between modes of toxicity were performed on elutriate samples from 23 of the above sites. The results from analysis of the sediments differed widely in the nature and degree of test responses. Significant correlation was found between the responses of the SMP electron transfer protocol and the whole-organism assay, and between the responses of the SMP electron transfer protocol and levels of zinc and sulfur, as determined by inductively coupled plasma spectroscopy.
Buffers in daphnid culture and bioassay
Authors: Keating Kathleen I. , Caffrey Paula B. , Dagbusan Brenda C.
Published: March 2010

When an algal diet is employed, or precipitation of dissolved inorganics during autoclaving is likely, or test circumstances introduce pH changes, addition of a buffer to daphnid culture or bioassay media is appropriate. Glycylglycine, employed in our research for 20 years, is unsuitable for general use because it requires microbe-free cultures. In contrast, n-hydroxyethyl piperazine-n-2-propane sulfonic acid (HEPPSO) and N-2-hydroxyethyl piperazine-N′-2-ethane sulfonic acid (HEPES) offer safe and effective pH control at 300 ppm for animals, 400 ppm for algae (weight excludes Na), with no requirement for microbe-free cultures. No negative effects on fecundity, monitored in both single and multigeneration tests, or on vigor, measured by acute bioassay performance, were observed. The 48-h LC50 for glycylglycine is approximately 4,500 ppm. No deaths occur at or below 10,000 ppm of either HEPES or HEPPSO. When bioassayed against zinc (as chloride), animals reared in cultures buffered by HEPES, HEPPSO, or glycylglycine and tested in unfed acute bioassays performed similarly, allowing 100% survival in 1,000 ppb in 48 h with an LC50 of approximately 1,750 ppb.
Subchronic sensitivity of one-, four-, and seven-day-old fathead minnow (Pimephales promelas) larvae to five toxicants
Authors: Pickering Quentin H. , Lazorchak James M. , Winks Kelly L.
Published: March 2010

The fathead minnow (Pimephales promelas) larval survival and growth test was used to evaluate the relative sensitivity of 1-, 4-, and 7-d-old larvae to five contaminants, KCl, NaCl, 1-octanol, carbaryl, and benzaldehyde. The no observable effect concentration (NOEC) for survival of the two inorganic compounds, KCl and NaCl, was not affected by age of the larvae. The subchronic valve (SCV) for NaCl was always determined by survival. Hypothesis testing of biomass always gave the same NOEC for the three age groups for each of the two inorganic compounds, and a minimum significant difference (MSD) was always calculable. The effect of 1-octanol on growth was more sensitive than the effect on survival in eight of the nine toxicity tests. Within a set of 1-, 4-, and 7-d-old larvae tests the SCV varied only twofold; however, between sets of tests the variation was fourfold. The SCV of carbaryl was determined by the effect on growth in five of six tests. Except for one test the SCV varied only twofold. The 1-d larvae were more sensitive to benzaldehyde than 1- and 7-d larvae in two sets of tests. The SCV was determined on the basis of survival for 1-d-old larvae and on the basis of growth for 4- and 7-d-old larvae.
A method for assessing sublethal effects of contaminants in soils to the earthworm, Eisenia foetida
Authors: Gibbs Mitchell H. , Wicker Linda F. , Stewart Arthur J.
Published: March 2010

We developed and tested a procedure that allows quantification of the effects of soil contaminants on earthworm (Eisenia foetida) growth and reproduction. The procedure monitors isolated pairs of earthworms and generates a higher ratio of data per organism than other commonly used procedures. It also incorporates an accurate technique for measuring adult growth, has high sensitivity compared to the Organization for Economic Cooperation and Development (OECD) 14-d acute toxicity test, and is cost effective. We applied the method to a variety of soil-testing problems. A food-and-substrate trial using artificial soil demonstrated the sensitivity of the method and the need for food supplementation to stimulate earthworm reproduction. Application of the procedure to assess efficacy of a soil bioremediation technology revealed the advantage of measuring both growth and reproduction and highlighted the usefulness of a single integrated measure of these two responses. The method also was used as a fast-screening analysis for field soils in a large-scale ecological risk assessment. Finally, a reference toxicant, used in dilution series, demonstrated that responses of E. foetida using our method were similar to their responses in the OECD artificial-soil test method. The results of this study indicate that this procedure can be used both for regulatory and compliance needs within the framework of ecological risk assessment.
The effects of land-use characteristics and acid sensitivity on the ecological status of maryland coastal plain streams
Authors: Hall Lenwood W. , Scott Mark C. , Killen William D. , Anderson Ronald D.
Published: March 2010

A 2-year study was conducted to evaluate the ecological status of 12 acid-sensitive and 12 non-acid-sensitive Maryland coastal plain streams during the spring, summer, and fall of 1992 to 1993. An index of biotic integrity (IBI) for fish, chemical parameters, and physical habitat conditions were evaluated in these streams. Correlations of land-use activities (forested streams vs. agricultural dominated streams) and watershed size were identified in the coastal plain streams with biological, chemical, and physical conditions. These data were also used to determine if a poor IBI for coastal plain stream fish can be related to stream sensitivity from acidic inputs.

Physical habitat was more important than water quality in determining IBI values for the 2-year period. Acid sensitivity was also important in influencing the IBI but the influence of acid sensitivity was overshadowed by physical habitat. When variation in physical habitat was accounted for among sites, the IBI in nonacid-sensitive streams was higher than in acid-sensitive streams. Initial results demonstrated that IBI values were higher in agricultural dominated streams when compared to forested streams. Consideration of only two dominant land-use types caused oversimplification of these results because urban land use (often associated with negative effects) was positively correlated with forested streams and negatively correlated with agricultural streams.
Effects of chronic pesticide stress on wildlife populations in complex landscapes: Processes at multiple scales
Authors: Maurer Brian A. , Holt Robert D.
Published: March 2010

Populations exposed to pesticides may often be divided into subpopulations, where some subpopulations are exposed to pesticides and others are not. We consider three models for such populations. The first is a simple discrete time model with no density-dependent reproduction. The second is a continuous time model that includes density-dependence for populations not exposed to pesticides. In both models, populations exposed to pesticides are assumed to decline geometrically (exponentially in the continuous time model). Migration between exposed and safe habitat patches is symmetric, so that all individuals leaving safe patches enter exposed patches and vice versa. The rate is assumed to be the same for both kinds of patches. The conditions for persistence of the population in the landscape are the same for both models. Increasing migration rate between patches decreases the ability of the population to persist. Populations that have low rates of increase in safe habitat patches have greater difficulty persisting than those with high rates of increase in safe patches. The toxicity of the pesticide also affects population persistence. More toxic pesticides that result in higher rates of death and/or lower rates of birth in exposed habitat patches lower the ability of the population to persist in the landscape. We consider an additional set of models of a metapopulations that persist because of a balance between colonization and local extinction. In such systems, pesticides may endanger regional persistence by reducing the pool of sites available for colonization. We conclude with an outline of important future directions for theoretical research intended to elucidate the impact of pesticides on populations spatially complex landscapes.
The layered and historical nature of ecological systems and the risk assessment of pesticides
Authors: Landis Wayne G. , Matthews Robin A. , Matthews Geoffrey B.
Published: March 2010

The community conditioning hypothesis is used as a framework in which to place the layers of effects during and after pesticide intoxication. Community conditioning states that information about the history of a system can be and is written at a variety of organismal and ecological levels. This historical component or etiology determines the future dynamics of a system. The storage of information concerning prior stressor events has been observed in a variety of compartments. Fish populations have been observed to have different genetic structures in populations that have been exposed to toxicant stressors. Analysis of biomarker data from field experiments reveals a variety of patterns, some due to the location of the field plots. Treatment groups within a series of microcosm experiments maintain their identities long after the degradation of the toxicant. The dynamics of the treatment groups in multivariate ecological space are characteristic of a particular treatment. Other microcosm systems differentially respond to invasion depending upon the order of the inoculation of the biotic components, even though at the time of the invasion the systems are indistinguishable. A major factor in the uncertainty of pesticide risk assessment will be the unknown etiology of the system of interest.
Biomonitoring with sentinel plants to assess exposure of nontarget crops to atmospheric deposition of herbicide residues
Authors: Felsot Allan S. , Bhatti Muhammad A. , Mink Gaylord I. , Reisenauer G.
Published: March 2010

In regions of highly diversified agriculture, herbicides used in one field may not be compatible with crops growing in nearby fields. Injury to nontarget crops may occur from drift or localized atmospheric transport of herbicide residues. Pea, bean, and corn seedlings have been used as sentinels to detect atmospheric deposition of trace residues. Seedlings were exposed at various locations throughout south central Washington and exchanged on a weekly basis with a new set of plants. Plants were returned to a lath house and observed over 3 weeks for development of symptoms indicative of probable exposure to four classes of herbicides—sulfonylureas, phenoxyacetates, aminophosphonic acids, and bipyridiliniums. The most frequently observed symptoms on sentinel plants were chlorotic spots on the upper leaf surfaces; such symptoms were created under controlled conditions by exposing plants to aerosols of the sulfonylurea (SU) herbicide chlorsulfuron. For 3 years, the greatest incidence of probable SU symptoms was detected during April; however, occurrence of symptoms was not correlated with periods of maximum use of SU herbicides on wheat in the region. The results suggested a general atmospheric loading of herbicides with occasional deposition, rather than point source drift. Further tests are needed to quantitate the exposures of sentinel plants and determine if chlorotic spots are associated with adverse physiological effects.
Interactions of Cd and Cu in anaerobic estuarine sediments. II. Bioavailability, body burdens and respiration effects as related to geochemical partitioning
Authors: Rule Joseph H. , Alden Raymond W.
Published: March 2010

The relationship between Cd and Cu distribution in sediment geochemical fractions and their bioavailability was studied. A fine-sandy textured estuarine sediment was treated with all combinations of 0, 2.5, and 5 mg/kg Cd and 0, 12, and 25 mg/kg Cu using the chloride salts of each metal. Grass shrimp (Palaemonetes pugio), blue mussel (Mytilus edulis), and hard clam (Mercenaria mercenaria) were exposed to the treated sediments in aquaria with 20 ppt artificial seawater for 14 d. Sediments were sequentially extracted before and after organism exposure to determine the exchangeable, easily reducible, organic-sulfide, moderately reducible, and acid extractable phases. Low mortalities were observed for all organism types and none were attributable to any of the treatments. The Cd and Cu concentrations in the easily reducible and organic-sulfide phases were found to be significantly related to the bio-availability of these metals. The most highly significant relationship was established between Cd in the easily reducible phase and body burden of Cd in the blue mussel. Notable interactions were found between Cd and Cu in some of the geochemical phases, body burdens, and respiration rates. Metal uptake, respiration, and interactions were highly dependent on the test species. A significant correlation was found between increased body burden and depressed respiration for Cd but not for Cu. Multiple regression models are used to describe these relationships. It appears that the interactive responses in the organisms are driven primarily by the sediment geochemical effects and mediated by individual organism processes. These results underscore the necessity of multicomponent (multielement) studies in assessing the fate and effects of toxic elements in the environment.
Comparative response of Ceriodaphnia dubia and juvenile Anodonta imbecillis to pulp and paper mill effluents discharged to the tennessee river and its tributaries
Authors: McKinney Aubrey D. , Wade Donald C.
Published: March 2010

The responses of Ceriodaphnia dubia (daphnid) in a 7–d chronic daily-renewal bioassay and 6–d-old juvenile Anodonta imbecillis (paper pondshell mussel) in a 9–d acute daily-renewal bioassay are compared. Values for relative sensitivity to selected complex, industrial, whole-effluent samples were generated following determination of either observed or calculated no-observable-effect concentrations (NOEC). Results from tests using effluents from six pulp and paper products facilities in the Tennessee River Valley indicate that A. imbecillis juveniles are substantially more sensitive than C. dubia to selected effluents. It is suggested that a juvenile mussel bioassay should be used to assess the toxicity of effluent releases to waters with freshwater mussel resources.
Field evaluation of the EPA (kenaga) nomogram, a method for estimating wildlife exposure to pesticide residues on plants
Authors: Pfleeger Thomas G. , Hayes Robert , Ratsch Hilman , Wickliff Carlos , Fong Anne
Published: March 2010

The Kenaga nomogram was developed by the U.S. Environmental Protection Agency (EPA) in the mid 1970 s and has since been used prior to the registration of a pesticide to estimate the maximum potential pesticide residue level on plant material in the food chain of wildlife. The objective of this study was to evaluate the nomogram using field data. Six pesticides representing a variety of pesticide classes were applied to 15 plant species. Five of the six nomogram categories were tested with plant parts representing differences in surface morphology (i.e., glabrous vs. pubescent leaves). The sixth category was a mixed-grass community seeded with three grass species. Pesticide residue levels were determined the day of application and up to 32 d afterward. While the linear nomogram model does not represent the data as well as other models, relatively few data points (10%) collected on the day of pesticide application exceeded the nomogram predictions. The one systemic pesticide tested had degradation rates similar to nonsystemic pesticides in most categories. Present nomogram categories were significantly different from each other in most cases. However, the forage category should be combined with the leaves and leafy-crop category and have higher estimated residue levels than the Kenaga nomogram. A considerable amount of variation occurs in the level of pesticide residue on plant materials even under controlled experimental conditions and therefore nomogram values should be used as an estimate only until actual field residue data are available. The nomogram, with modifications, appears to be a reasonable regulatory device if careful thought is given in selecting the plant category for making residue estimates.
Modulation of cupric ion activity by pH and fulvic acid as determinants of toxicity in Xenopus laevis embryos and larvae
Authors: Buchwalter David B. , Linder Greg , Curtis Lawrence R.
Published: March 2010

An ion-specific electrode measured cupric ion activity modulated by fulvic acid (FA) and pH in a series of modified Frog Embryo Teratogenesis Assay—Xenopus (FETAX) toxicity assays. Hydrogen ion concentration was the primary determinant of cupric ion activity, while FA played a smaller but significant role. Fulvic acid was a weak copper complexing agent at pH 5.50. At pH 5.50 there was slight reduction of ionic activity and a subsequent attenuation of copper toxicity with 5.0 mg/L FA. At pH 7.50, FA also had a mild attenuating effect on copper toxicity. At pH 6.50, copper was strongly complexed by FA at total copper (TCu) concentrations below its pH-dependent solubility limit. At TCu concentrations above the solubility limit FA enhanced toxicity. There was more cupric ion activity measured in the presence of 0.5 and 5.0 mg/L FA than without it at TCu concentrations above the solubility limit. The proposed mechanism for this behavior was FA action as a nucleation inhibitor. Under the chemical conditions of the pH 6.50 experiments, a stable supersaturation of copper was formed, resulting in a more toxic aqueous matrix.