bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractAcid-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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &gt;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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 &lt; 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

Abstract
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

Abstract
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 &lt;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

Abstract
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 &gt; hydroxyatrazine &gt; didealkylatrazine &gt; deethylhydroxyatrazine &gt; 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

AbstractThe 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.
Evidence for particle-mediated transport of 2,3,7,8-tetrachlorodibenzofuran during gas sparging of natural water
Authors: Friesen Kenneth J. , Loewen Mark D. , Fairchild Wayne L. , Lawrence Sharon G. , Holoka Morris H. , Muir Derek C. G. 
Published: March 2010

Abstract
Gas sparging was conducted in lake enclosures previously treated with [4,6-3H]-2,3,7,8-tetrachlorodibenzofuran (TCDF) to determine the fugacity or dissolved concentration of this hydrophobic contaminant under field conditions. Using a Henry's law constant for TCDF of 1.7 ± 0.8 Pa.m3/mol, measured experimentally by gas sparging, apparent dissolved TCDF concentrations of 7 to 22 pg/L were determined. These results were 100 times greater than concentrations of TCDF obtained by extraction of water samples from the same enclosures with dichloromethane. TCDF was found to be highly associated with naturally occurring particles in the water column, with 40% of sorbed TCDF associated with the 0.1- to 3-μm size fraction. The results are interpreted in light of previous reports that indicate that bubbles are effective scavengers of bacteria and particulates in natural waters, transporting these solids across the water/air interface as bubbles burst at the water surface. In the laboratory addition of a yeast suspension increased the amount of TCDF sparged from aqueous solutions, confirming that particle-mediated movement of highly sorbed contaminants can influence apparent water concentrations measured by gas sparging of natural waters.