bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical and chemical parameters of sediment extraction and fractionation that influence toxicity, as evaluated by microtox®
Authors: Ho Kay T.Y. , Quinn James G.
Published: March 2010

Several physical and chemical parameters of sediment extraction and fractionation of organic compounds that influence bioassay results were evaluated. Each parameter was evaluated with a photoluminescent bacterial bioassay (Microtoxr̀) as an end point. Three solvents (acetonitrile, acetone, and methanol) were studied for their ability to extract toxic organic components from marine sediments. Acetone extracted the most toxicity, with no difference between acetonitrile and methanol. Two methods of fractionating sediment extracts (silica-gel-column chromatography [SGCC] and acid-base fractionation) were compared. SGCC was more useful because it resulted in a wider range of responses and was faster to perform than acid-base fractionation. Microtox was used to rank four marine sediments with respect to toxicity and to determine if one chemical class (or fraction) was consistently more toxic among different sediments. With some caveats, Microtox results agreed with general chemical concentration trends and other bioassay results in distinguishing between contaminated and noncontaminated sediments. Although results indicated there was not a consistently most toxic fraction among sediments, there was a consistently least toxic fraction. The effect of sediment storage time on toxicity was also evaluated. Results indicated that the most stable chemical fraction (containing nonpolar hydrocarbons) did not change toxicologically for 30 weeks, whereas the more chemically active fraction (containing ketones, quinones, and carboxyls) changed as soon as one week.
Hexachloroethane obscurant: Assessing tree foliage injury
Authors: Sadusky M. C. , Simini M. , Skelly J. M. , Checkai R. T. , Wentsel R. S.
Published: March 2010

Open-top chambers were used to determine the relationships between a hexachloroethane (HC) obscurant, zinc deposition, and foliar injury of tree species indigenous to military training facilities. Eight eastern U.S. tree species were exposed four times to three exposure regimens (0x, 1x, 2x) of the obscurant, measured as Zn, during the 1990 growing season. Plots received ambient or charcoal-filtered air for comparison purposes. Black locust (Robinia pseudoacacia L.) and black cherry (Prunus serotina Ehrh.) were the most sensitive species, exhibiting significant (p < 0.05) necrotic leaf spot, chlorotic mottle, and marginal necrosis of leaves at the 2x levels throughout the season. Defoliation was also greater (p < 0.05) in exposed vs. unexposed plots. Sugar maple (Acer saccharum Marsh.) injury was different among exposure regimens (p < 0.05) only near the end of the season. Sweet gum (Liquidambar styraciflua L.), eastern white pine (Pinus strobus L.), loblolly pine (Pinus taeda L.), and Virginia pine (Pinus virginiana Mill.) were asymptomatic. Charcoal filtration did not affect severity of symptoms. Zinc deposition was positively correlated (p < 0.05) with most of the symptoms on black locust and black cherry. The HC obscurant in the concentrations used in this study adversely affected these species.
Effects of incubation temperature and warm-water misting on hatching success in artificially incubated mallard duck eggs
Authors: Stubblefield William A. , Toll Paul A.
Published: March 2010

Artificial incubation of eggs is employed in one-generation avian reproduction studies conducted under laboratory conditions. Maximizing overall hatch success while minimizing variability due to experimental methods can increase statistical power for quantifying effects caused by the test material. This study evaluated the effects of incubation temperature and daily warm-water misting of duck eggs on hatching success in a 2 × 2 matrix. Treatment groups were subjected to incubation temperatures of 37.2 or 37.5°C, with (M) or without (NM) misting. Eggs were collected daily from 15 breeding pairs per treatment group during a 10-week laying period. Within appropriate test groups, eggs were misted daily throughout the 24-d incubation and 4-d hatching period. Hatching success (as a percentage of fertile eggs) was 71, 32, 18, and 10 for the 37.5 M, 37.5 NM, 37.2 M, and 37.2 NM groups, respectively. Egg weight significantly decreased, as a percentage of initial egg weight, in misted eggs; no temperature-related differences in egg weight were observed. Results indicate that an incubation temperature of 37.5°C with daily warm-water misting proved to be the most effective treatment for maximizing overall hatching success.
Rapid toxicity screening tests for aquatic biota 1. Methodology and experiments with Daphnia magna
Authors: Janssen C. R. , Persoone G.
Published: March 2010

A promising new and rapid toxicity screening test was developed, the concept and principles of which are presented. The method consists of visual observation of in vivo inhibition of an enzymatic process, using a fluorescent substrate. Juvenile Daphnia magna was exposed to a toxicant dilution series for 1 h, after which the substrate was added and the enzymatic inhibition (absence of fluorescence) was observed visually, using a long-wave UV light (385 mm). The 1-h EC50 results of 11 pure compounds are presented and compared to the conventional 24- and 48-h Daphnia magna EC50s. All 1-h “fluorescence” EC50s were of the same order of magnitude and correlated very well with the 24- and 48-h EC50s. The sensitivity and reproducibility of this cost-effective screening test were compared to those of the Microtoxr̀ test. The scope for application and the potential of this new rapid toxicity screening test are evaluated.
Bioaccumulation and elimination of chlordane by selected intertidal benthic fauna
Authors: Wilcock Robert J. , Pridmore Rick D. , Thrush Simon F. , Cummings Vonda J. , Hewitt Judi E. , Smith Terrence J.
Published: March 2010

Bioaccumulation and elimination of nine principal components of technical chlordane applied to a previously uncontaminated intertidal sand flat were observed in adults of the bivalve species Chione stutchburyi and Tellina liliana, the gastropod Amphibola crenata, and polychaetes (Glycera americana, Nicon aestuarinensis, and Platynereis australis). The patterns of accumulation differed markedly between species, depending on whether the organisms acquired chlordane predominantly from the sediment phase or from both sediment and water phases. The surface-dwelling (Amphibola crenata) or surface-feeding (Tellina liliana) species attained chlordane levels up to three times that of the suspension feeder, Chione stutchburyi, a short time after application. The lipid-normalized bioconcentration curves for both shellfish species declined to similar steady-state values, which suggested that simple equilibrium partitioning between organism lipid and sediment organic carbon phases regulates long-term bioconcentration. The composition of the adsorbed chlordane, although very similar to that of the technical product applied to the sand flat, also showed some species dependence with a preference for the more chlorinated components of chlordane to accumulate in the sediment-feeding species. No traces of the metabolites oxychlordane and heptachlor epoxide were found in any of the species tested over the 100-d duration of the study.
Modeling reproductive toxicity in Ceriodaphnia tests
Authors: Bailer A. John , Oris James T.
Published: March 2010

A model for Ceriodaphnia dubia reproductive toxicity outcomes is presented. This model assumes that the number of young is a Poisson-distributed random variable and that the mean number of young can be modeled using an exponential term involving a polynomial in the test concentrations. Given these assumptions, a modeling procedure for reproductive outcomes is developed and is used to derive an estimate of potency of the chemical under test. Confidence intervals for this estimate are obtained using a bootstrap resampling procedure.
Fate of linear alkylbenzene sulfonate in the environment
Authors: McAvoy D. C. , Eckhoff W.S. , Rapaport R.A.
Published: March 2010

An extensive monitoring study was conducted to determine the fate of linear alkylbenzene sulfonate (LAS) during wastewater treatment and in the environment. Results showed that LAS was highly removed during activated sludge (99.3 ± 0.6%), lagoon (98.5 ± 1.8%), oxidation ditch (98.0 ± 4.2%), and rotating biological contact (96.2 ± 6.1%) treatment, with poorer removals observed at trickling filter (77.4 ± 15.5%) facilities. Concentrations of LAS in anaerobically digested sludge (10,462 ± 5170 μg/g) were one to two orders of magnitude greater than those observed for aerobically digested sludge (152 ± 119 μg/g), illustrating that LAS is rapidly degraded during aerobic sludge treatment. Receiving water concentrations of LAS in rivers of low effluent dilution were generally < 50 μg/L. Elevated river sediment concentrations of LAS were observed only below the outfall of trickling filter treatment plants (59.7-182.1 μg/g). Alkyl chain lengths of LAS averaged 12.0 carbon units in most environmental compartments, with the exception of sludge solids and river sediments, in which an enrichment of longer chain lengths was observed. Measured concentrations of LAS in river waters under critical low flow conditions were in agreement with PG-GRiDS model predictions [5], thus supporting the validity of the modeling approach.
Reduced chromosomal puffing in Chironomus tentans as a biomarker for potentially genotoxic substances
Authors: Bentivegna C.S. , Cooper K.R.
Published: March 2010

Chromosomal puffing in the salivary glands of larval Chironomus tentans was developed as a biomarker for genotoxic substances. Reduced chromosomal puffing was considered an indication of decreased RNA synthesis. Third- or fourth-instar larvae were exposed to test chemicals in an artificial substrate under static conditions. Chromosomes from glands of individual larvae were stained with methyl green and pyronin Y. The widths of Balbiani rings I and II (large puffs on chromosome IV) were measured. Three carcinogens with different mechanisms of action were tested, benzo[a]pyrene (BaP), actinomycin D (Act D), and dimethylnitrosamine (DMN). Puff size was statistically reduced by all three chemicals with varying potency. Lowest-observable-effect levels (LOEL) were 0.5 nmol BaP, 6.0 nmol Act D, and 243,000 nmol DMN. The degree of response was influenced by exposure time, applied dose, individual sensitivity, and possibly chemical hydrophobicity. Biomarker specificity was determined by testing a weak carcinogen, benzo[e]pyrene (BeP), and an acutely toxic noncarcinogen, naphthalene (NP). The effective dose of BeP (LOEL = 250 nmol) was four orders of magnitude higher than that of BaP. Only lethal doses of NP had statistically significant effects on puff size, LD50 = 25,000 (34,300-15,700) nmol. Approximately 40% of the larvae in our laboratory population appeared tolerant to the effects of BaP. Advantages of this biomarker were its association with a known mechanism of action and measurement of the whole-organism integrated response.
Acid-volatile sulfide (AVS) in a seasonally anoxic mesotrophic lake: Seasonal and spatial changes in sediment AVS
Authors: Howard Dorothy E. , Evans R. Douglas
Published: March 2010

Acid-volatile sulfide (AVS) is an operational definition for the sulfides removed from sediment by cold acid extraction. It has been proposed that this fraction could be used as an indicator of divalent metal toxicity (e.g., Cd, Ni, Hg), as it increases the metal-binding capacity of sediments and hence renders metals unavailable to biota. Before AVS can be used as a predictive tool in freshwater systems, we must develop a better understanding of the impact of seasonal turnover events on its geochemistry. An in-depth study of spatial and temporal variation in AVS concentrations in a seasonally anoxic mesotrophic lake is presented. Comparisons are made to AVS in other lakes, with reference to its utilization as a sediment toxicity parameter. Results indicate that AVS increases during anoxic periods and that lake morphology is important due to sediment focusing. Seasonal variations in AVS concentration were observed that may change the potential toxicity of metals in freshwater sediments.
Degradation of organochlorine pesticides, particularly endosulfan, by Trichoderma harzianum
Authors: Katayama Arata , Matsumura Fumio
Published: March 2010

A fungus, Trichoderma harzianum, was found to degrade DDT, dieldrin, endosulfan, pentachloronitrobenzene, and pentachlorophenol but not hexachlorocyclohexane. The fungus degraded endosulfan under various nutritional conditions throughout its growth stages. Endosulfan sulfate and endosulfan diol were detected as the major fungal metabolites of endosulfan. Piperonyl butoxide, when added to the growth medium, completely inhibited the endosulfan degradation. Di-n-propyl malaoxon also inhibited the overall endosulfan degradation, but under such an inhibitory condition the formation of endosulfan sulfate was still observed. Using a cell-free preparation from Trichoderma harzianum, we could demonstrate that endosulfan metabolism in vitro was stimulated by exogenously added NADPH. Together with the evidence that the initial metabolic product of endosulfan was endosulfan sulfate, we concluded that the major enzyme system responsible in Trichoderma harzianum responsible for degradation of endosulfan is an oxidative system.
Chemical and toxicological testing of composted explosives-contaminated soil
Authors: Griest W.H. , Stewart A.J. , Tyndall R.L. , Caton J.E. , Ho C.-H. , Ironside K.S. , Caldwell W.M. , Tan E.
Published: March 2010

Static-pile and mechanically stirred composts of explosives-contaminated soil at the Umatilla Army Depot Activity (UMDA, Umatilla, OR) in a field composting optimization study were characterized chemically and toxicologically. The concentrations of extractable explosives (e.g., 2,4,6-trinitrotoluene) in the composts and their aqueous leachates, the mutagenicity of organic solvent extracts from the composts, and the toxicity of compost aqueous leachates to Ceriodaphnia dubia all decreased considerably with 20 d of composting. After 44 d (mechanical composters) or 90 d (static piles) of composting, the toxicity, mutagenicity, and concentrations of extractable explosives decreased more than 90% in some cases. The composting efficiency was generally inversely proportional to the percentage (v/v) of contaminated soil. Composting in static piles was efficient up to about 20% (v/v) of contaminated soil; composting in the mechanically stirred composters was efficient up to about 25% soil. Mechanical composting was more efficient than composting in static piles. The main conclusion of this study is that composting can effectively remediate explosives-contaminated soil and sediment. However, low levels of explosives and metabolites, bacterial mutagenicity, and leachable toxicity to Ceriodaphnia may remain after composting. The sources of residual toxicity and mutagenicity and the ultimate fate of the explosives are unknown.
Kinetics, products, mechanisms and QSARs for the hydrolytic transformation of aromatic nitriles in anaerobic sediment slurries
Authors: Peijnenburg Willie J.G.M. , de Beer Karin G.M. , den Hollander Henri A. , Stegeman Miranda H.L. , Verboom Hans
Published: March 2010

The degradation of several substituted benzonitriles was examined in anaerobic sediment-water systems under laboratory conditions. Formation of the corresponding benzoic acids was the main transformation process taking place. The pseudo-first-order rate constants of this process were shown to depend on both the chemical structure of the starting compound and the sediment characteristics. The starting compounds were selected with the aim of obtaining a maximum variation in chemical reactivity and physical properties, and the sediments were selected with the aim of assessing several environmental factors influencing the kinetics of transformation. Quantitative structure-activity relationships were developed for both ortho- and meta/para-substituted nitriles by relating pseudo-first-order disappearance rate constants for reductive hydrolysis of 27 aromatic nitriles in anoxic sediment slurries to some readily available molecular descriptors. The best correlations were obtained with the octanol/water partition coefficient of the nitriles and the summation of the inductive constants of the substituents as parameters. The correlations were strongly enhanced by taking into account the fraction of the compounds sorbed to the solid phase. Also it was found that upon correction for sorption, rate constants for reductive hydrolysis of three substituted benzonitriles obtained in six sediment samples did not differ significantly. Thus the obtained relationships may be used to calculate rates of transformation of given aromatic nitriles in given sediment systems
External validation of a QSAR for the acute toxicity of halogenated aliphatic hydrocarbons
Authors: Eriksson Lennart , Jonsson Jörgen , Berglind Rune
Published: March 2010

The validation of the predictive capability of a quantitative structure-activity relationship (QSAR) is a significant step toward the construction of a reliable model. This point is discussed and illustrated with data for a class of halogenated aliphatic hydrocarbons. For this class of compounds, a QSAR concerning their acute toxicity toward rat was recently published. This QSAR is verified in this study by selecting and testing an external validation set comprising six compounds. The QSAR is also used for predicting the acute toxicity of 38 nontested members of this class.
An alternative avian population estimate for overdispersed populations for use in mark-recapture studies of pesticide effects
Authors: Madrigal J.L. , Carter M.W. , Parrish J.R. , Booth G.M. , Fischer D.L.
Published: March 2010

Statistical models that have been commonly applied to mark-recapture/resighting data, such as the Jolly-Seber estimate, assume that capture and recapture/resighting probabilities are constant for all birds. This assumption is likely false. An alternative approach that is based on the beta-binomial distribution that allows for heterogeneous capture/recapture is presented. Use of the approach is illustrated with data obtained in a field study of NEMACUR® 15G applications. A total of 24,000 simulations indicated that the power of the beta-binomial in detecting a 10% reduction in survival varies from 56.2 to 99% in resighting data and is more than 84% in recapture data. Population estimates were obtained using the maximum likelihood method. Under conditions of heterogeneous probabilities, more precise estimates of population size were produced with this approach than with the Jolly-Seber method.
Comparative diazinon toxicity in guppy and zebra fish: Different role of oxidative metabolism
Authors: Keizer Johannes , D'Agostino Giuseppina , Gramenzi Franco , Vittozzi Luciano , Nagel Roland
Published: March 2010

Guppies pretreated with 1.1 μmol/L diazinon (0.5 times the LC50 with the guppy) for 7 d were less susceptible to the toxicity of the compound. The LC50 in these fish was about five times higher than that in nonpretreated animals. The lethal body burden and the slope of the concentration-response curve of diazinon in pretreated guppies were similar to those in zebra fish. The 7-d pretreatment of zebra fish with 12 μmol/L diazinon (0.5 times the LC50 with the zebra fish) did not affect the susceptibility of this species to diazinon. The pretreatment of guppies resulted in a strong inhibition of the formation of diazoxon and pyrimidinol during incubations of diazinon with the hepatic postmitochondrial supernatant. During exposure of guppies and zebra fish to diazinon, the tissue concentration of the metabolite, pyrimidinol, initially increased and then declined to very low levels. In the guppy, concurrently with the decrease of the metabolite concentration, the parent compound began accumulating again after a temporary steady state. The hypotheses of this paper are that the toxicity of diazinon in the guppy is due to its metabolism to a highly toxic metabolite, likely diazoxon; and in zebra fish or pretreated guppies having low rates of diazinon metabolism toxicity is due to the accumulation of the parent compound.
pH-Dependent toxicity of Cd, Cu, Ni, Pb and Zn toCeriodaphnia dubia, Pimephales promelas, Hyalella aztecaandLumbriculus variegatus
Authors: Schubauer-Berigan Mary K. , Dierkes Joseph R. , Monson Philip D. , Ankley Gerald T.
Published: March 2010

The speciation and bioavailability of metals are known to be affected by pH. Although many studies have focused on effects on metals of pH changes resulting from lake acidification (i.e., pH change 7 to 4), metal toxicity changes at higher pH values (i.e., pH 6-9) are of great interest to those performing effluent and sediment toxicity testing and toxicity identification evaluations (TIEs). In addition, most previous studies have addressed metal toxicity changes with pH to water-column organisms rather than to benthic or epibenthic species. We tested the acute toxicity of five metals (Cd, Cu, Ni, Pb, and Zn) to Ceriodaphnia dubia, Pimephales promelas, Hyalella azteca, and Lumbriculus variegatus at three pH values (6.3,7.3, and 8.3) in very hard reconstituted water (hardness 300-320 mg/L as CaCO3). Toxicity of Cd, Ni, and Zn was greatest at pH 8.3 and least at pH 6.3 to most of these species. Conversely, the toxicity of Cu and Pb was greatest at pH 6.3 and least at pH 8.3 to most of the species. The acute toxicity of most of the metals to Lumbriculus variegatus was very low and occasionally was above the aqueous solubility of the metal salts in the reconstituted water.
The effects of sodium selenite and selenomethionine on murine limb development in culture
Authors: Rousseaux C.G. , Politis M.J. , Keiner J.
Published: March 2010

Excessive selenium in the environment causes perturbed embryonic development in birds; however, excessive selenium in mammals has not been shown to cause similar maldevelopment. The present study was performed to determine whether the lack of selenium-induced limb defects in mammals is due to either differences in pharmacokinetics or tissue sensitivity to the compound, or both. Sodium selenite (SS) and selenomethionine (SM) were added to BGJb medium containing 20% fetal bovine serum, in which limbs from CD-1 mouse embryos taken 12 d following conception were cultured. Concentrations of SS and SM ranged from 2 to 20 times the level of selenium normally present in fetal bovine serum (0.2, 0.6, 1.0, 2.0, or 4.0 μig/ml). Limbs were grown for 72 h, fixed, stained with Alcian blue GX to highlight cartilage anlagen, and analyzed to determine tissue and anlage areas and shape factors. Sodium selenite induced a concentration-response maldevelopment of ulnar, radius, and humerus anlagen and delayed development of phalanges, whereas SM did not. Changes in development became obvious at SS levels four times normal (0.6 μg/ml). The size and length of anlagen also decreased (p < 0.0001). At six times the concentration of SS (1.0 μg/ml), areas occupied by cartilage anlagen were decreased 20-fold, with virtually no chondrogenesis evident in phalanges at higher concentrations. The results of these studies indicate that SS can cause deficits in early mammalian limb development if the element is allowed to reach the developing tissue, whereas the SM does not. We conclude that tissue differences in response and placental transfer may account for the differences seen among species.
Metal concentrations in feathers of birds from Papua New Guinea forests: Evidence of pollution
Authors: Burger Joanna , Laska Mark , Gochfeld Michael
Published: March 2010

We used the feathers of seven species of birds from New Guinea highland forests to examine concentrations of heavy metals and selenium. We tested the null hypotheses that there were no species, food type, or elevation differences in the concentrations of mercury, lead, cadmium, selenium, chromium, and manganese in the feathers of adults. All species had nondetectable levels of mercury (< 10 ppb). There were significant species differences in cadmium, lead, chromium, selenium, and manganese. Common smokey honeyeaters (Melipotes fumigatus, a fruit and flower feeder) had the lowest levels of all metals; blue-grey robin (Peneothello cyanus, mainly insectivorous) had the highest cadmium and manganese; and several species of birds of paradise (mainly frugivorous) had the highest lead levels. Lead levels were relatively high compared to those reported from feathers of other birds, attributable to the use of leaded gasoline.
Chemical transformation of toxic metals by a Pseudomonas strain from a toxic waste site
Authors: Blake Robert C. , Choate Donna M. , Bardhan Smriti , Revis Nathaniel , Barton Larry L. , Zocco Thomas G.
Published: March 2010

Pseudomonas maltophilia strain O-2, isolated from soil at a toxic waste site in Oak Ridge, Tennessee, catalyzed the transformation and precipitation of numerous toxic metal cations and oxyanions. When a viable inoculum (1%) of O-2 was introduced into nutrient broth containing Hg(II), Cr(VI), Se(IV), Pb(II), Au(III), Cd(II), Te(IV), or Ag(I), effective removal of the toxic metal was complete within 1, 1, 2, 2, 2, 4, 5, and 7 d, respectively. The NADPH-dependent reduction of Hg(II) to Hg0 was catalyzed by an inducible mercuric reductase. The reduction of selenite and tellurite to their insoluble elemental forms appeared to be mediated by an intracellular glutathione reductase that utilized the spontaneously formed bis(glutathio)Se(II) or bis(glutathio)Te(II), respectively, as pseudosubstrates. The three-electron reduction of hexavalent chromium was catalyzed by a membrane-bound chromate reductase. The enzymatic basis for the remaining metal transformations was not immediately apparent. It is anticipated that Pseudomonas maltophilia and related organisms could eventually be exploited for the removal of toxic metal wastes from selected, heavily polluted sites.
Analysis of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) for the estimation of potential toxicity in aquatic sediments
Authors: Allen Herbert E. , Fu Gongmin , Deng Baolin
Published: March 2010

Acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) are operationally defined methods for the analysis of sulfide and associated metals in aquatic sediments. The SEM-to-AVS ratio has been useful in explaining the results of bioassay tests of metal toxicants. This paper describes apparatus that can be used in the evolution of sulfide from sediments and a method for the analysis of the evolved sulfide and the liberated metal. The method was studied with respect to gas flow rate, digestion time, and acid concentration. Liberated and trapped sulfide was determined by a colorimetric method of analysis. Using the apparatus and conditions described in this paper, the colorimetric method of analysis is capable of detecting AVS at concentrations normally encountered with a recovery of sulfide of at least 90%. High precision is possible if this apparatus is used. The limit of detection of the method is approximately 0.01 m̈mol/g dry sediment. We added 6 M HC1 to produce a final concentration of approximately 1 M for the release of the AVS and SEM from unheated samples. We found that sulfide was not released from pyrite (FeS2) or copper sulfide (CuS) under these conditions. The liberation of copper from the two studied sediments indicates that copper was probably associated with another phase in these sediments. AVS is stable for several weeks in refrigerated or frozen samples.
Soil microcosm for testing the effects of chemical pollutants on soil fauna communities and trophic structure
Authors: Parmelee Robert W. , Wentsel Randall S. , Phillips Carlton T. , Checkai Ronald T. , Simini Michael
Published: March 2010

A microcosm technique is presented that uses community and trophic-level analysis of soil nematodes and microarthropods to determine the effects of chemicals on soil systems. Forest soil was treated with either copper (0, 100, 200, 400, and 600 m̈g g−1), p-nitrophenol (0, 20, 40, 80, and 160 m̈g g−1), or trinitrotoluene (0, 25, 50, 100, and 200 m̈g g−1). Nematodes were sorted into bacterivore, fungivore, herbivore, and omnivore-predator trophic groups, and a hatchling category. Microarthropods were sorted to the acarine suborders Prostigmata, Mesostigmata, and Oribatida; the insectan order Collembola; and a miscellaneous group. Omnivore-predator nematodes and mesostigmatid and oribatid mites were the groups most sensitive to copper and were significantly reduced at levels as low as 100 m̈g g−1 copper. Total nematode and microarthropod numbers declined above 200 m̈g g−1 copper. Trophic structure analysis suggested that high sensitivity of nematode predators to intermediate levels of copper reduced predation on herbivore nematodes and resulted in greater numbers of nematodes compared to controls. p-Nitrophenol was very toxic to the nematode community, and all trophic groups were significantly reduced above 20 m̈g g−1. However, there was no effect of p-nitrophenol on microarthropods. Trinitrotoluene had no significant negative effect on total abundance of either group of soil fauna, but oribatids were significantly reduced at 200 m̈g g−1. Our results demonstrated that soil nematodes and microarthropods were sensitive indicators of environmental contaminants and that trophic-structure and community analysis has the potential to detect more subtle indirect effects of chemicals on soil food-web structure. We conclude that microcosms with field communities of soil microfauna offer high resolution of the ecotoxicological effects of chemicals in complex soil systems.
Aqueous-, pore-water-, and sediment-phase cadmium: Toxicity relationships for a meiobenthic copepod
Authors: Green Andrew S. , Chandler G. Thomas , Blood Elizabeth R.
Published: March 2010

Comparative effects of aqueous-, pore-water-, and sediment-phase cadmium on mortality of an infaunal laboratory-cultured copepod, Amphiascus tenuiremis, were determined using acute 96-h bioassays. Experimental design included five cadmium concentrations, three replicates per concentration, and 50 adult copepods per replicate for each of the exposures. Exposures included cadmium solubilized in seawater only (aqueous), whole sediment (i.e., pore water and sediment), and pore water only. In addition, two whole-sediment bioassays were compared in which pore-water cadmium concentrations were altered experimentally but sediment concentrations remained the same. Results of these experiments showed that for Amphiascus tenuiremis, cadmium is most toxic in the aqueous phase, less toxic in the pore-water phase, and least toxic in the sediment-bound phase. The lowered toxicity of cadmium in the pore water was most likely due to complexation of cadmium with DOC, because concentrations of DOC were six times higher in the pore-water phase than in the aqueous phase. In whole sediments, pore-water-phase cadmium was the primary source of acute toxicity, as sediment-associated cadmium contributed negligible effects.
A critique of ecosystem health concepts and indexes
Authors: Suter Glenn W.
Published: March 2010

Because people wish to preserve their health and do something equivalent for ecosystems, the metaphor of ecosystem health springs to mind. This paper presents the argument that it is a mistake for environmental scientists to treat this metaphor as reality. First, the metaphor fails because it misrepresents both ecology and health science. Ecosystems are not organisms, so they do not behave like organisms and do not have properties of organisms such as health. Also, health is not an operational concept for physicians or health risk assessors because they must predict, diagnose, and treat specific states called diseases or injuries; they do not calculate indexes of health. Second, attempts to operationally define ecosystem health result in the creation of indexes of heterogeneous variables. Such indexes have no meaning; they cannot be predicted, so they are not applicable to most regulatory problems; they have no diagnostic power; effects on one component are eclipsed by responses of other components; and the reason for a high or low index value is unknown. Their only virtue is that they reduce the complex array of ecosystem responses to various disturbances to one number with a reassuring name. A better alternative is to assess the real array of ecosystem responses so that causes can be diagnosed, future states can be predicted, and benefits of treatments can be compared.
Impact assessment of spray drift from silvicultural aerial applications of permethrin on aquatic invertebrates using mosquito bioassays
Authors: Helson B.V. , Payne N.J. , Sundaram K.M.S.
Published: March 2010

Permethrin (Pounce®) was applied at 70 g active ingredient per hectare by fixed-wing aircraft to a 16-ha jack and red pine plantation under application and meteorological conditions that were highly conducive for insecticide drift. Mortalities of an indicator aquatic insect species, Aedes aegypti mosquito larvae, and corresponding permethrin residues in shallow, artificial aquatic habitats, along with droplet densities on ground Kromekote® cards, were measured along five lines downwind and crosswind of the spray block. At 30, 60, 120, 180, and 240 m downwind, larval mortalities averaged 40, 39, 51, 18, and 34%; permethrin residues averaged 1.4, 1.1, 1.2, 0.6, and 0.8 μg/L; and droplet densities averaged 25, 22, 17, 14, and 10 droplets per centimeter squared, respectively. At similar distances crosswind of the block, mortalities were 60, 53, 11, 1, and 0%; residues to 180 m were 1.6, 2.6, 1.1, and 0.3 μg/L; and droplet densities were 30, 22, 12, 2, and 0.1 droplets per centimeter squared, respectively. Mortalities and residues were not high for such shallow water (6.7 cm depth), particularly beyond 120 m, and were less than or similar to the values predicted from a swath-superposition model. Impact on sensitive aquatic arthropods and stream insects in deeper water (≥25 cm), more representative of natural habitats, is predicted to be insignificant at such distances. A buffer zone of 150 m around productive water bodies (depth ≥25 cm) is suggested for aerial permethrin applications to such plantations.
Impact of hexazinone and metsulfuron methyl on the phytoplankton community of a mixed-wood/boreal forest lake
Authors: Thompson D.G. , Holmes S.B. , Thomas D. , Macdonald L. , Solomon K.R.
Published: March 2010

The impact of two herbicides on the phytoplankton community of a typical forest lake was investigated using in situ enclosures. Chronic exposure to hexazinone resulted in concentration-dependent depression of DO, which mirrored reductions in biomass of all dominant phytoplankton groups (Cyanophyta, Chlorophyta, Chrysophyta, Cryptophyta, and Bacilliarophyceae). Although effects observed at the lowest treatment level of hexazinone (0.01 mg L−1) were transient, no evidence of recovery in biomass was discernible at higher test concentrations within the 77 d of investigation. In contrast, metsulfuron methyl at concentrations as high as 1.0 mg L−1 (approximately 40× the worst-case expected environmental concentration [EEC]) induced only slight transient effects and only in the Cyanophyta. For hexazinone, 95% C.I.s (0.01-0.07 mg L−1) for nonlinear estimates of EC50 (biomass reduction) were generally an order of magnitude below the EEC for accidental overspray (0.8 mg L−1) and below the EEC estimated for drift inputs associated with aerial applications in forest vegetation management. Results of this replicated concentration-response study demonstrate substantial, statistically significant, and persistent impacts on natural phytoplankton communities chronically exposed to hexazinone at levels >0.1 mg LT−1. In contrast, no similar effects were observed in phytoplankton communities exposed to metsulfuron methyl at levels well in excess of its EEC values.
Pulmonary exposure of mice to “engineered” pseudomonads influences intestinal microbiota populations
Authors: George S. Elizabeth , Kohan Michael J. , Creason John P. , Claxton Larry D.
Published: March 2010

Microbial biotechnology applications have prompted research into their potential impacts on human health and the environment. In this study, a mouse model was used to evaluate indirect effects (e.g., alteration of the intestinal microbiota) of pulmonary exposure to representative biotechnology agents (Pseudomonas aeruginosa strain AC869 and Pseudomonas cepacia strain AC 1100) selected for their ability to degrade hazardous chemicals. CD-I® mice were challenged intranasally with approximately 103 or 107 colony-forming units (cfu) of strain AC869 or 108 cfu of strain AC1100. At time intervals, clearance of the microorganisms and effects on resident microbiota were determined. When the low (103 cfu) dose was administered, strain AC869 was not recovered from the small intestine but was detectable in the cecum and lungs 3 h after treatment and persisted in the nasal cavity intermittently for 14 d. Treatment of animals with 107 cfu of strain AC869 resulted in detection 14 d following treatment. Strain AC869 challenge modified the small intestinal anaerobe count and cecal obligately anaerobic gram-negative rods (OAGNR) and lactobacilli. Following exposure, Pseudomonas cepacia strain AC1100 persisted in the lungs for 7 d and was recovered from the small intestine, cecum, and nasal cavity 2 d following treatment. Strain AC1100 treatment impacted the small intestinal anaerobe count, OAGNR counts, and reduced lactobacilli numbers. Strain AC1100 also altered the cecal OAGNR and lactobacilli. Therefore, pulmonary treatment of mice with Pseudomonas aeruginosa or cepacia affects the balance of the protective intestinal microbiota, which may cause further negative health effects (e.g., harbored pathogen multiplication, opportunistic pathogen invasion, bacterial translocation).
Assessing the aquatic hazard of some branched and linear nonionic surfactants by biodegradation and toxicity
Authors: Dorn Philip B. , Salanitro Joseph P. , Evans Sharon H. , Kravetz Louis
Published: March 2010

An aquatic hazard assessment was conducted for branched and linear nonionic surfactants using toxicity and biodegradation measurements. Four nonionic alcohol ethoxylate surfactants with different degrees of branching (ranging from 0.1, essentially linear, to 4.0 internal methyl groups per hydrophobe) were evaluated for neat surfactant toxicity, degradation in laboratory sewage treatment units, and aquatic toxicity of treated effluents. Acute testing with neat surfactants showed ranges for EC50s of 1.3 to 11.6 mg/L for Daphnia, 1.6 to 6.1 mg/L for Pimephales promelas (fathead minnow), and 1.5 to 11.4 mg/L for Microtox®. Chronic testing of algae showed NOECs of 1 to 10 mg/L and maximum acceptable toxicant concentrations (MATCs) of 0.8 to 14.2 mg/L. Seven-day chronic estimation tests showed MATCs of 0.6 to 41.4 mg/L for Pimephales promelas and 1 to 14 mg/L for Daphnia. Effluents collected from treatment units receiving a 50-mg/L surfactant feed at 25°C showed no acute toxicity to either Daphnia or fathead minnows, with the exception of a unit containing nonylphenol ethoxylate. Chronic effluent toxicity was greatest in effluent from the nonyl-phenol ethoxylate unit and least in the effluent from the linear alcohol ethoxylate unit. Chronic toxicity of the highly branched C13 alcohol ethoxylate effluent was greater than that for the linear alcohol ethoxylate unit effluent.
Effects of cationic surfactant exposure to a bivalve mollusc in stream mesocosms
Authors: Belanger S.E. , Davidson D.H. , Cherry D.S. , Farris J.L. , Reed D.
Published: March 2010

Effects of the cationic surfactant lauryl trimethyl ammonium chloride (C12-TMAC) on growth, reproduction, cellulolytic enzyme activity, and larval colonization of Asiatic clams (Cor-bicula fluminea) were investigated in experimental stream mesocosms. Clams from three different populations and of two known morphotypes were evaluated for growth in two 8-week experiments in fall 1989 and spring 1990. Growth was impaired at 185 μg TMAC per liter or greater for both seasons and was not morphotype dependent. Mortality, cellulolytic enzyme activity, and adult reproductive condition were not altered up to concentrations of 1153 μg/L. However, larval clam (ped-iveliger) colonization was affected at concentrations of 43 μg/L. It is not known at this time to what extent the effects on pediveligers would be manifested relative to recruitment to later life stages. These findings were compared to a published safety assessment for mono-alkyl quanternaries, of which TMAC is a member. The findings reported here do not substantially alter conclusions from previous studies; however, clams appear to be among the more sensitive taxa studied thus far.
A long-term study of anaerobic dechlorination of PCB congeners by sediment microorganisms: Pathways and mass balance
Authors: Rhee G. -Yull , Sokol Roger C. , Bethoney Charlotte M. , Bush Brian
Published: March 2010

Reductive dechlorination of PCBs by Hudson River sediment microorganisms was investigated using individual congeners, 2,3,4,2′,4′,5′-, 2,4,5,2′,4′,5′-, 2,3,4,5,6-, 2,4,2′,4′-, and 3,4,3′,4′-chlorobiphenyls (CBPs) in long-term studies lasting 15 to 20 months. The dechlorination of 2,3, 4,2′,4′,5′-CBP yielded 2,4,5,2′,4′-, 2,4,2′,4′-, 2,4,2′,5′-, and 2,4,2′-CBPs; notably absent was 2,2′-CBP. Yet, the total molar concentration of all congeners decreased with time and at 15 months accounted for only 25% of the initial concentration of the parent compound. 2,3,4,5,6-CBP produced 2,3,5,6-, 2,4,6-, and 2,6-CBPs. At 15 months the sum of all congeners accounted for only about 50% of the initial amount of the parent congener. On the other hand, 2,4,5,2′,4′,5′-CBP yielded six daughter products, including 2,2′-CBP, and did not show any decrease in total molar concentration even at 20 months. 2,4,2′,4′-CBP did not show any change at 15 months. These results indicate that anaerobic PCB biotransformation may include mechanisms other than dechlorination and that the mechanisms are congener dependent. Biphenyl was detected with 3,4,3′,4′-CBP, indicating complete dechlorination; however, it accounted for < 10% of the total molar loss. 14C-labeled tracer of this congener showed that all radioactivity was in the hexane fraction, suggesting that transformation products were hydrophobic.
Extraction of silicones from soil
Authors: Lehmann Robert G.
Published: March 2010

Silicone polymer, polydimethylsiloxane (PDMS), was extracted from soil incubated at 100 mg kg−1 for 0, 1,3, 7, 14, and 28 d with mean recovery of 95.4% (σ = 2.1%). From four agricultural soils incubated for one week at 1, 10, and 100mg kg−1, mean extraction recovery was 95.6% (σ = 3.2%). The method is now being used in 14C studies on the fate of silicones in the soil environment and will later be used for extraction of silicones from field samples.
The feasibility of stocking largemouth bass in 0.04-ha mesocosms used for pesticide research
Authors: Howick Gregory L. , deNoyelles Frank , Dewey Sharon L. , Mason Larry , Baker Debra
Published: March 2010

Piscivorous fish can exert considerable influence on the structure and function of aquatic ecosystems. However, current U.S. Environmental Protection Agency guidelines for aquatic meso-cosm tests for pesticide registration assume that mesocosms with a volume of <1,000 m3 are too small to support a piscivorous fish population. We tested this assumption between early April and mid-December by stocking ten 0.04-ha, 345-m3, earthen pond mesocosms with 30 adult bluegill and two of the 10 with 0, 10, 20, 40, or 80 fingerling largemouth bass. As the stocking rate of bass increased, the average size and condition factor of bass and the number of recovered juvenile bluegill decreased, whereas the average length and mass of juvenile bluegill increased. The total biomass of juvenile bluegill in each pond was not affected by bass stocking rate. Adult bluegill were not affected by bass stocking rate, except for a slight increase in total biomass in the 80-bass ponds. Bass stocking rate had marginal impacts on the crustacean zooplankton and no significant effect on emergent insects. The survival of reasonable numbers of juvenile bluegill over a wide range of bass densities indicates that 0.04-ha mesocosms can be feasibly stocked with piscivorous fish. The key is probably sufficient macrophyte abundance to provide cover for the juvenile bluegill.
Movement and degradation of [14C]atrazine in undisturbed soil columns
Authors: Kruger Ellen L. , Somasundaram L. , Coats Joel R. , Kanwar Ramesh S.
Published: March 2010

The movement and degradation of [14C]-atrazine were studied in undisturbed soil columns (15 × 60 cm) taken manually from a field with no previous pesticide history. The experiment was conducted indoors under controlled temperature conditions. Three weeks after application of [14C]-atrazine (2.2 kg a.i. per hectare) to the soil surface, the columns were leached at weekly intervals for 12 weeks. Approximately 1.2% of the applied 14C was recovered in the leachate over the 12-week period, which corresponds to an atrazine (plus degradation products) concentration of 7.6 μg/L. On completion of the last leaching event, the columns were cut into 10-cm increments and analyzed for [14C]-atrazine and degradation products. Seventy-seven percent of the 14C applied to soil columns remained in the upper 10 cm and included primarily atrazine (9%) and soil-bound residues (57%). Deethylatrazine was the predominant degradation product in the top 10 cm (3.6%). Other degradation products were found in the top 10 cm at relative concentrations of deisopropylatra-zine > hydroxyatrazine > didealkylatrazine > deethylhydroxyatrazine > deisopropylhydroxyatra-zine. Uncharacterized polar metabolites in the top 10 cm accounted for 6% of the applied 14C. Atrazine, deethylatrazine, and deisopropylatrazine were found at all depths. In addition, didealkylatrazine was detected to the 50-cm depth, hydroxyatrazine to the 30-cm depth, and deethylhydroxyatrazine to the 20-cm depth.
A COMPARISON of the effects of two methods of acclimation on aerobic biodegradability
Authors: Watson Heather M.
Published: March 2010

The acclimation or adaptation of microorganisms to organic chemicals is an important factor influencing both the rate and the extent of biodegradation. In this study two acclimation procedures were evaluated in terms of their effectiveness in enhancing biodegradation, their relative ease of use in the laboratory, and the implications for biodegradability testing. In the single-flask procedure, microorganisms were acclimated for 2 to 7 d in a single acclimation flask at constant or increasing concentrations of the test chemical without transfer of microorganisms. In the second procedure, the enrichment procedure, microorganisms were acclimated in a series of flasks over a 21-d period by making adaptive transfers to increasing concentrations of the test chemical. Acclimated microorganisms from each procedure were used as the source of inoculum for subsequent biodegradation tests in which carbon dioxide evolution was measured. Six chemicals were tested: quinoline, p-nitrophenol, N-methylaniline, N,N-dimethylaniline, acrylonitrile, and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. Microorganisms acclimated in the single-flask procedure were much more effective than those acclimated in the enrichment procedure in degrading the test chemicals. The single-flask procedure is more convenient to use, and it permits monitoring of the time needed for acclimation. The results from these studies have implications for the methodology used in biodegradation test systems and suggest caution before adopting a multiple-flask, enrichment acclimation procedure before the performance of standardized tests for aerobic biodegradability.