bluuebunny/crossref_metadata_2025 huggingface dataset:
Metier (modular ecotoxicity tests incorporating ecological relevance) for difficult substances: Aedes aegypti (diptera: culicidae) initial module test development using 3,4-dichloroaniline
Authors: Ribeiro Rui , Lima Luís M. , Gonçalves Fernando , Scares Amadeu M.V.M.
Published: March 2010

There is an urgent need to develop regulatory guidelines for compounds classed as “difficult substances” - poorly water-soluble, volatile, readily biodegradable or photodegradable, or hydrolytically unstable compounds. The project METIER (modular ecotoxicity tests incorporating ecological relevance) aims to develop a series of ecologically relevant toxicity tests allowing the full breadth of response of aquatic organisms to chemical contaminants to be assessed under realistic exposure scenarios. This involves the development of a standard flow-through exposure system and a series of modular toxicity tests linked to a mechanistic physiological model of contaminant effects. This paper addresses the initial stages of the development and test design of the module with Aedes aegypti larvae (Diptera: Culicidae), using 3,4–dichloroaniline (3,4–DCA), a poorly water-soluble compound included in the European Community Priority 1 List of Chemicals. A viable culture system, suitable test medium, and the experimental design for loading effects and test duration are investigated. Moreover, the dissolution process and stability of the 3,4–DCA solutions are presented. Up to 50 mg L−1 3,4-DCA was dissolved without the use of a carrier. There was no loss of chemical during 4 d after dissolution. Use of one larva per vessel in 96-h acute toxicity tests is recommended. Also, 24-, 48-, 72-, and 96-h acute toxicity tests were run in low and high volumes of medium. Results of these tests reveal that A. aegypti larvae are more sensitive in higher volumes of test medium and belong to a moderately tolerant group of organisms regarding 3,4-DCA acute toxicity.
Tests for bioequivalence of control media and test media in studies of toxicity
Authors: Erickson Wallace P. , McDonald Lyman L.
Published: March 2010

Statistical tests of the classical (null) hypothesis–that there is no difference in effects of control media and test media– are commonly used to make statistical inferences toward the no-observed-adverse-effect concentration. However, failing to reject this hypothesis is not considered as scientific proof the hypothesis is true. An effect may exist, but high variation due to inadequate replication, variation in experimental units, or imprecise measurement techniques may yield data for which the hypothesis is not rejected. An experiment may also be too precise, yielding effects that are statistically significant but not biologically important. We propose the use of tests of bioequivalence of control media and test media to alleviate these unsatisfactory characteristics of tests of the classical hypotheses for regulatory decisions. We review and illustrate the test for bioequivalence using acute and chronic toxicity data. We also define a procedure for determining the level of effect at which there will be high power to refute the hypothesis that there is a lack of bioequivalence if in fact the biological response in the control media is identical to the response in the test media.
Reversed-phase separation of estuarine interstitial water fractions and the consequences of C18 retention of organic matter
Authors: Ozretich Robert J. , Smith Lawrence M. , Roberts Fredrick A.
Published: March 2010

Data are presented on the application of the reversed-phase separation technique for the determination of dissolved organic compounds in estuarine interstitial water. Thirty-seven neutral, nonpolar organic compounds were equilibrated with interstitial water, extracted by emulsion-free gentle liquid-liquid extraction, and quantified using surrogate internal standards. The extraction and quantitation procedures were insensitive to dissolved organic carbon concentration (DOC, 1 to 55 mg C/L). Gross dissolved organic carbon retention by the C18 matrix (7 ± 2%) was similar to the range reported for fresh water; significant regressions of apparent, DOC-normalized, partition coefficients (K′doc) versus compound solubility and octanol/water partition coefficients (Kow) were determined. An inverse relationship between K′doc and DOC concentrations, similar to that reported in fresh water, was found, but was reduced or eliminated for many compounds by accounting for the retained bound compound in the calculation of K′doc; failure to account for C18 retention of DOM in determining freely dissolved concentrations of high K′ow organic compounds could result in overestimates of this fraction. Partition coefficients of selected compounds between Aldrich humic acid and distilled water were similar to those found in other studies using radiolabeled compounds.
Biodegradation of glycol ethers in soil
Authors: Gonsior Stanley J. , West Robert J.
Published: March 2010

Because of the widespread use of glycol ethers in applications ranging from consumer products to use as chemical intermediates, there is a need to better understand the fate of these compounds in the environment. Soil biodegradation studies were conducted for three propylene glycolethers: 1-methoxy-2-propanol, 1-phenoxy-2-propanol, and 1-methoxy-2-propanol acetate. The test compounds were labeled with carbon-14 at either the methoxy or phenoxy substituents. Biodegradation of the three compounds was observed in two sandy loam soils. The time required for disappearance of 50% of the test compounds ranged from <1 d at 0.2 ppm (w/w) to <7 d at 107 ppm. Degradation rates were slower in a sandy soil, reflecting the lower concentration of microorganisms present. No significant accumulation of intermediate products was observed, and ultimate yields of 14CO2 were in the range of 40 to 65% of the initial concentration. Results indicated that the glycol ethers were degraded in a variety of soils under aerobic conditions.
Fate and effects of triclopyr ester in a first-order forest stream
Authors: Thompson Dean G. , Kreutzweiser David P. , Capell Scott S. , Thomas David R. , Staznik Bozena , Viinikka Ty
Published: March 2010

The fate and the effects of triclopyr butoxyethyl ester (TBEE) were investigated in a first-order forest stream. Quantification of TBEE in stream-water samples showed maximal concentration of 0.848 and 0.949 μg ml−1 at sampling stations nearest two discrete injection points. Average TBEE concentrations ranged from 0.32 μg ml−1 at stations nearest injection points to 0.02 μg ml−1 approximately 225 m downstream. Periods of exposure to aqueous TBEE concentrations in excess of 0.001 μg ml−1 ranged from 55 min in fast-flowing upstream locations to 120 min at slower, downstream sampling locations. Simultaneous quantitation of triclopyr acid (TRI) residues in stream-water samples indicated that natural degradative mechanisms rapidly converted TBEE to TRI, and that sorption to natural allochthonous materials occurred as chemical pulses moved downstream. Chemical behaviour resulted in short-term, pulse-type exposures to TBEE, with decreasing magnitude and slightly increasing duration in relation to downstream distance. Short-term, low-level exposures generated in this stream treatment resulted in slightly elevated drift (∼3- to 4-fold increase) for up to 36 h, but no measurable reductions in abundance of benthic invertebrates. Increases in chlorophyll a concentrations in epilithic periphyton from treated sections indicated short-term eutrophication or growthregulation effects of the herbicide applications.
Spatial and temporal trends of contaminants in eggs of wading birds from San Francisco Bay, California
Authors: Hothem Roger L. , Marois Katherine C. , Wainwright Susan E. , Roster Douglas L. , King Kirke A. , Keldsen Timothy J.
Published: March 2010

Between 1989 and 1991, reproduction by black-crowned night-herons (Nycticorax nycticorax) and snowy egrets (Egretta thula) was studied at sites in San Francisco Bay. Eggs were collected from these and other bay sites and from South Wilbur Flood Area, a reference site in California's San Joaquin Valley. Eggs were analyzed for inorganic trace elements, organochlorine pesticides, and polychlorinated biphenyls (PCBs). Results were compared among sites and years and with results of previous studies. There was some evidence of impaired reproduction, but concentrations of contaminants were generally lower than threshold levels for such effects. Egg hatchability was generally good, with predation being the factor that most limited reproductive success. Mean PCB concentrations were generally higher in eggs from the south end of San Francisco Bay than from the north, but the only temporal change, an increase, was observed at Alcatraz Island. There were spatial differences for p,p′-DDE in night-heron eggs in 1990, but the highest mean concentration of DDE was in night-heron eggs from South Wilbur in 1991. Temporal declines in maximum concentrations of DDE in eggs were observed in the bay, but means did not change significantly over time. At Bair Island in the southern end of the bay, mean concentrations of mercury decreased while selenium increased in night-heron eggs over time, but there were no clear bay-wide spatial or temporal trends for either element.
An inexpensive fathead minnow egg incubation and toxicant exposure system
Authors: Diamond Stephen A. , Oris James T. , Guttman Sheldon I.
Published: March 2010

We report on an inexpensive, easily constructed system for hatching fathead minnow eggs and maintaining hatched larvae for growth and survivorship studies. Data are presented to illustrate the use of the system for toxicant exposures. This system has applications for both field and laboratory studies.
Adaptation to fluoranthene exposure in a laboratory population of fathead minnows
Authors: Diamond Stephen A. , Oris James T. , Guttman Sheldon I.
Published: March 2010

Tolerance of toxicant exposure is common in polluted sites in nature. However, in most cases, the processes underlying tolerance acquisition are not well understood. In the case of exposure to polycyclic aromatic hydrocarbons (PAHs) in particular, reports are lacking on the capacity for tolerance acquisition. To evaluate the potential for adaptation to this class of contaminants we exposed a large laboratory population of fathead minnows to fluoranthene, commonly a major constituent of PAH contamination. The exposure concentration chosen did not cause mortality but was sufficient to diminish reproductive capacity in exposed breeding fish relative to a control population. This level of exposure also significantly diminished hatching success and larval survivorship in the exposed population. The estimated value of selection against susceptibility (the product of all assessments of effect) was 0.67. Tests for tolerance acquisition included comparative larval 96-h LC50 determinations, and comparative juvenile median time to death (LT50) determinations. Enhanced tolerance was not apparent in the LC50 determinations, although an examination of the concentration-response distribution suggested an adverse effect due to egg and larval exposure to fluoranthene prior to the test. In contrast, results of the comparative LT50 determination indicated that the exposed population was approximately 30% more tolerant, relative to the control population, when exposed to an acutely toxic concentration of fluoranthene. These results suggest that tolerance to PAH exposure can occur in nature and that this population-level response needs to be examined relative to other recognized effects in PAH-contaminated areas.
Relative sensitivity of five benthic invertebrate species to reference toxicants and resin-acid contaminated sediments
Authors: Hickey Christopher W. , Martin Michael L.
Published: March 2010

Five sediment-dwelling native New Zealand freshwater invertebrate species (amphipod, Chaetocorophium c.f. lucasi; clam, Sphaerium novaezelandiae; oligochaete, Lumbriculus variegatus; tanaid, Tanais standfordi; and the burrowing mayfly, Ichthybotus hudsoni) were assessed for their suitability for sediment toxicity testing by comparison of sensitivity to reference toxicants [phenol and pentachlorophenol (PCP)] and contaminated sediments. The 96-h EC50 values at 20°C showed a greater range in test sensitivity for phenol (30-fold range) from the most sensitive test, amphipod (8.1 mg/L), to the least sensitive one, clam (243 mg/L), compared with PCP (14-fold range), with amphipod the most sensitive test species (0.13 mg/L) and tanaid the least sensitive (1.8 mg/L). Clam reburial was a more sensitive end point than was lethality for phenol (by 20-fold) and PCP (by 2.4-fold). Four of the test species, excluding the tanaid, showed good 10-d survival in reference muds (≥87%) but lower survival in sand sediments (≥79%). Bleached kraft mill sediment containing high resin-acid concentrations (total 1,900 mg/kg dry weight) showed significant reductions in amphipod survival (15%), clam reburial (30%), and oligochaete survival (17%), and reproduction (49%). Amphipods, clams, and oligochaetes were the most promising species for sublethal test development.
Use of loading rates to establish dioxin criteria for land application of sludge
Authors: Thiel David A. , Martin Stephen G. , Goodman Beth B. , Sullivan John R.
Published: March 2010

A methodology derived from empirical field and laboratory data on wildlife toxicology, chemical concentrations, and loading rates is developed for defining criteria for protecting wildlife exposed to landspread materials containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and TCDD-like compounds. The method controls mass loading, giving it clear advantages over soil-concentration-based criteria in situations where material is spread in a relatively thin layer on the surface and not incorporated into the soil. It also controls dioxin toxic equivalents in the target organism rather than in the landspread material. It achieves a high level of protection for bird embryos by applying a safety factor to a no-observed-adverse-effect level (NOAEL) derived from egg toxicity data and combining this adjusted NOAEL with bioaccumulation data from the most efficient avian accumulator of TCDD on a landspread site. Assuming that bird embryos are among the most sensitive organisms to TCDD in the terrestrial environment, dioxin restrictions adequate to safeguard eggs will protect other wildlife inhabiting landspread sites. Using this methodology, the Wisconsin Department of Natural Resources has derived the following wildlife dioxin criterion for surface spreading (i.e., no incorporation) a paper industry sludge: The sum of the mass of TCDD plus 0.0013 times the mass of 2,3,7,8-tetrachlorodibenzofuran (TCDF) shall not exceed 1.3 mg per hectare.
Hydrolysis of para-substituted benzonitriles in water
Authors: Masunaga Shigeki , Lee Wolfe N. , Hayase Kohji
Published: March 2010

The transformation of para-substituted benzonitriles was studied in buffered distilled water. The elevated temperature experiments revealed that benzonitriles are hydrolyzed to the corresponding benzoic acids through benzamide intermediates. For 4-chlorobenzonitrile, the pseudo-first-order rate constants adhered to the Arrhenius equation with an activation energy of 40.5 kJ · mol−1 and collision frequency of In 6.23 × 104. Alkaline hydrolysis was dominant at pH values above 8, while neutral hydrolysis was important between pH 5 and 7. The quantitative structure-reactivity relationship (QSRR) analysis of 14 para-substituted benzonitriles showed that the first-order rate constants obtained in phosphate buffer (pH 7.7) at 85°C, based on a combination of neutral and alkaline hydrolysis, were correlated with Hammett σp constants.
Parameters affecting the adsorption of hexachlorobenzene to natural sediments
Authors: Jepsen Rich , Borglin Sharon , Lick Wilbert , Swackhamer Deborah L.
Published: March 2010

Many of the toxic contaminants introduced into aquatic systems are hydrophobic and, because of this, they are transported with the suspended sediments and eventually incorporated into the bottom sediments. Understanding the dynamics of contaminant sorption to sediments is therefore important in understanding and predicting the transport and fate of contaminants. In the present study, the adsorption and the partitioning of hexachlorobenzene (a hydrophobic organic chemical) to natural sediments from the Detroit River were investigated by means of batch mixing experiments. Experiments were conducted over a long period (2 to 5 months) to reach a steady-state equilibrium and at different sediment concentrations (10, 100, 500, 2,000, and 10,000 mg/L). It was found that the adsorption rate was greatest for small time and decreased to zero as time increased. For all concentrations, a steady-state equilibrium was always attained. Experiments quantitatively demonstrate the time-dependent effects of hexachlorobenzene dissolution, of the flocculation of colloidal matter in the water, and of the flocculation of the suspended sediments. Although a solids concentration effect on the partition coefficient was observed, it is shown to be due to the above processes. From the data, a true equilibrium partition coefficient as well as the approximate times to equilibrium can be determined.
Hexazinone effects on stream periphyton and invertebrate communities
Authors: Kreutzweiser David P. , Capell Scott S. , Sousa Brian C.
Published: March 2010

Experiments were conducted in laboratory test chambers and outdoor stream channels to measure the effects of hexazinone on stream periphyton and macroinvertebrate communities. All experimental units were treated at the nominal concentration of 2.7 mg/L, which represents the maximum expected environmental concentration in water from forest vegetation management applications. In laboratory flow-through tests, a 12-h exposure of stream periphyton on natural substrates to hexazinone resulted in a significant reduction in net photosynthetic activity, but no significant effects on periphyton biomass (chlorophyl-a concentration). Recovery from toxic effects was rapid, with no significant differences in photosynthetic activity among treated and control units within 3 h after the hexazinone concentrations were cleared. In stream channels treated for 12 h with hexazinone, there were no significant effects on periphyton biomass and no significant differences in invertebrate drift, compared to control channels. There were also no indications of adverse treatment effects on the invertebrate communities in the stream channels 14 d after the application. The treated and control channels differed in invertebrate community structure, as determined by a stepwise discriminant analysis [Wilks' lambda F equivalent (3,2) = 127.6, p = 0.007], and this was supported by a two-way ANOVA which showed a significant difference in abundance of macroinvertebrates [F(1, 56) = 10.5, p = 0.002] between treated and control channels, averaged over all taxa. However, subsequent pairwise t tests, when adjusted for multiple comparisons, were unable to identify significant differences between treatment levels for any of the 14 taxa with sufficient data for analysis. Although not significant, the comparison of means showed that abundance of most taxa was higher in the treated channels than in the controls.
The response of biota in experimental stream channels to a 24-hour exposure to the herbicide Velpar L®
Authors: Schneider Judith , Morin Antoine , Pick Frances R.
Published: March 2010

Outdoor experimental stream channels were used to examine the short-term impact of Velpar L® on periphyton and macroinvertebrates. Velpar L was added to five channels for 24 h while five additional, alternating channels served as controls. The concentration and the duration of the Velpar L treatment were chosen to mimic the pulse of herbicide carried to streams during rain events subsequent to Velpar L spraying. The mean concentration of hexazinone, the active ingredient, in the treatment channels varied over time from 145 μg L−1 to 432 μg L−1. Periphyton chlorophyll-a-specific productivity was reduced by 80% during the Velpar L addition. Within 24 h after the termination of the Velpar L addition, periphyton productivity returned to control levels. The 4-h EC50 value, 3.6 μg L−1 of hexazinone, for chlorophyll-a-specific productivity was lower than published bioassay results from single species tests. Mean periphyton biomass (chlorophyll-a per unit area of gravel substrate) and mean macroinvertebrate biomass, density, length, and drift were not significantly affected by the Velpar L addition. Although it appears that lotic systems are resilient to short-term exposure to Velpar L, the effects of repeated and chronic exposures on stream biota remain unexplored.
Validation of models on uptake of organic chemicals by plant roots
Authors: Polder Marieke D. , Hulzebos Etje M. , Jager D. Tjalling
Published: March 2010

The fate of a substance is governed by the distribution of the substance among soil, water, air, and biota, and by the concentration of the substance and its altered forms existing over a period of time in these media. As vegetable food forms a major part of the diet of both human beings and of cattle, the contamination of plants will have a large influence on the total daily intake of a substance. In this report the application of soil-plant transfer factors is investigated. The main goal was to find sufficient experimental data in the available literature, if possible adjusted for differences in experimental design, that could be used to evaluate the currently applied method in the uniform system for the evaluation of substances (USES). In this approach, concentrations in plant root and stem are estimated on the basis of an empirical relationship with the octanol/water partitioning coefficient. It was concluded that, for the purposes set in USES, the root concentration factor is an appropriate instrument for the estimation of residues in roots, whereas the application of the stem concentration factor is insufficient. Consequently, for aboveground plant parts, other approaches need to be explored, which can then be applied in the general risk assessment of substances.
Effects of octamethylcyclotetrasiloxane (OMCTS) on freshwater and marine organisms
Authors: Sousa Joseph V. , McNamara Pauline C. , Putt Arthur E. , Machado Mark W. , Surprenant Donald C. , Hamelink Jerry L. , Kent David J. , Silberhorn Eric M. , Hobson James F.
Published: March 2010

The toxicity of octamethylcyclotetrasiloxane (OMCTS) to representative freshwater and marine fish and invertebrates was investigated. Testing procedures followed Toxic Substance Control Act (TSCA) guidelines with chemical-specific adaptations as presented in the OMCTS Testing Consent Order (Docket OPTS-42071A). The physicochemical properties and behavior of OMCTS (i.e., high volatility, low water solubility) precluded the use of conventional experimental practices and exposure systems. Procedures and systems developed during these investigations provided a mechanism that produced exposure levels equal to the maximum achievable (i.e., “functional”) solubility of OMCTS in natural dilution waters. The toxicant delivery systems and exposure chambers were designed to minimize volatilization by elimination of the air/water interface. The flow-through systems maintained consistent exposure concentrations and adhered to U.S. Environmental Protection Agency (EPA) Guideline test performance criteria. The “functional” water solubility of OMCTS in freshwater and seawater ranged from 14 to 30 μg/L and from 6.0 to 9.0 μg/L, respectively. Functional water solubility appeared to vary slightly with test conditions and dilution water characteristics. Continuous exposures of 2 to 93 d were conducted during these investigations with daphnids (Daphnia magna), rainbow trout (Oncorhynchus mykiss), mysids (Mysidopsis bahia), and sheepshead minnow (Cyprinodon variegatus). The rainbow trout was determined to be the most sensitive species to OMCTS (14-d LC50 = 10 μg/L). At levels equal to the functional water solubility, OMCTS was not acutely toxic to D. magna, mysids, or sheepshead minnow. The survival of D. magna was reduced by 16%, relative to the control organisms, after 21-d exposures to 15 μg/L OMCTS; exposure to 7.9 μg/L OMCTS or less had no effect on daphnid survival or reproduction. No toxicity was observed at the highest concentration tested in a 93-d exposure of rainbow trout early life stages. The no-observed-effect concentration for this study was 4.4 μg/L, the same as determined in a 14-d extended acute study.
Bioconcentration by fish of a highly volatile silicone compound in a totally enclosed aquatic exposure system
Authors: Fackler Paul H. , Dionne Emily , Hartley Deborah A. , Hamelink Jerry L.
Published: March 2010

Two aqueous exposures of fathead minnows (Pimephales promelas) were conducted to determine the bioconcentration factor (BCF) for [14C]octamethylcyclotetrasiloxane (OMCTS). The high volatility, high sorptive capacity, and low water solubility of OMCTS required that the testing be conducted in a novel, totally enclosed, flow-through exposure system that prevented the volatilization of the test substance. In a preliminary study, fish were continuously exposed to OMCTS at a concentration of approximately 0.5 μg/L for 6 d. In the definitive study, fish were exposed for 28 d at approximately 0.3 μg/L. In each case, OMCTS exposures were followed by a 14-d depuration period. Water concentrations and fish residues were measured periodically in both studies. Data from the 6-d study resulted in a maximum measured BCF of 7,000. Model calculations based on data from the 6-d exposure phase predicted a steady-state BCF of 10,000 after 19 d of exposure. The definitive study resulted in a steady-state measured BCF of 12,400 after 28 d of exposure. Model calculations based on the measured data from the 28-d exposure phase provided an estimated BCF of 13,400. The OMCTS bioconcentration factors could be accurately estimated from the data produced during a 6-d continuous exposure. The use of innovative test systems was key to the development of useful bioconcentration data.
Octamethylcyclotetrasiloxane (OMCTS), a case study: Summary and aquatic risk assessment
Authors: Hobson James F. , Silberhorn Eric M.
Published: March 2010

This paper presents an aquatic ecological risk assessment, including an aquatic effects assessment, an exposure assessment, and a characterization of risk to aquatic organisms. In a number of acute and chronic studies with several aquatic species, octamethylcyclotetrasiloxane (OMCTS) toxicity was observed, but only after extended, continuous exposures of 7 to 14 d; survival was the only biological end point affected. The symptoms of toxicity observed were highly consistent with narcosis as the mechanism of action. For all aquatic toxicity testing, the lowest NOEC was 4.4 μg/L for rainbow trout in both 14-d and 90-d tests. The physicochemical characteristics of OMCTS (low solubility, high Kow, and very high Henry's law constant) indicate that the water concentrations should be low and transient, consistent with results of environmental-fate studies that demonstrate that OMCTS moves rapidly out of water. The primary route of release of OMCTS to the environment is associated with use in personal-care products, which would potentially result in release to air and water via public sewer systems. Environmental-fate models predict low concentrations of OMCTS in air and water. Monitoring studies indicate mean measured concentrations of OMCTS in sewage treatment plant effluents of 0.06 to 0.41 μg/L. Assuming 50% bioavailability of OMCTS and a dilution factor of three, calculated mean concentrations of dissolved OMCTS in surface waters range from 0.01 to 0.068 μg/L. Comparison of the lowest no-observed-effect concentration (NOEC) from all toxicity testing with this predicted range of surface water concentrations indicates a conservative margin of safety to 64 to 444 for aquatic organisms. Rapid volatilization and additional dilution in most aquatic environments will increase this margin of safety even further. Based on all available evidence, the risk of OMCTS to aquatic ecosystems is characterized as very low.
A preliminary evaluation of the relationship between bioconcentration and hydrophobicity for surfactants
Authors: Tolls Johannes , Sijm Dick T.H.M.
Published: March 2010

A statistical analysis was done of the relationship between hydrophobicity and bioconcentration parameters (uptake and elimination rate constants and bioconcentration factor) predicted by the diffusive mass-transfer (DMT) concept of bioconcentration developed previously. We employed polychlorinated biphenyls and benzenes (PCB/zs) as model compounds and the octanol/water partition coefficient as hydrophobicity parameter. We conclude that the model is consistent with the data. Subsequently, we applied the DMT concept to a set of preliminary bioconcentration data for surfactants using the critical micelle concentration (CMC) as hydrophobicity parameter. The obtained relationships qualitatively agree with the DMT concept, indicating that hydrophobicity is of great influence on surfactant bioconcentration. Finally, we investigated the hydrophobicity-bioconcentration relationships of surfactants and PCB/zs using aqueous solubility as common hydrophobicity parameter and found the relationships between the bioconcentration parameters and hydrophobicity to agree with the DMT concept. These findings are based on total radiolabel data. Therefore, they need to be confirmed using compound-specific surfactant bioconcentration data.
Acute toxicity of heavy metals for benthic epiphytic foraminifera Pararotalia spinigera (le calvez) and influence of seaweed-derived doc
Authors: Bresler Vladimir , Yanko Valentina
Published: March 2010

The acute toxicity of cadmium, copper, and mercury to the benthic epiphytic foraminiferan Pararotalia spinigera (Le Calvez) was investigated using seven different vital cytophysiological and cytochemical methods. The ability to enzymatically hydrolyze the fluorogenic substrates fluorescein diacetate or fluorescein dibutyrate was the most sensitive method of LC50 value determination. The LC50 (24-h) values for cadmium, copper, and mercury determined by this assay with fluorescein diacetate was 0.56, 1.4, and 0.07 μM, respectively. The content of seaweed-derived dissolved organic carbon (DOC), measured by absorbance at 436 nm, produced a dramatic increase of LC50 values for the heavy metals in a dose-dependent manner. “Intact” epiphytic foraminifera attached to seaweeds are less sensitive to acute toxicity of cadmium, copper, and mercury than are “detached” foraminifera.
Immunopathology of 8-week-old ring-necked pheasants (Phasianus colchicus) exposed to malathion
Authors: Day Brad L. , Walser Mary M. , Sharma Jagdev M. , Andersen David E.
Published: March 2010

In addition to their acute neurotoxic effects, some organophosphorus compounds have been shown to have immunotoxic properties. Alterations in the immune system may lead to chronic morbidity and/or mortality that is not readily apparent at the time of initial exposure. Because it often inhabits land that is intensely farmed, the ring-necked pheasant (Phasianus colchicus) may be a suitable biomonitor of agroecosystems, especially those used in the production of corn. We examined immunopathologic effects of a widely used organophosphate insecticide, malathion, on 8-week-old, cage-reared ring-necked pheasants 3 d after a single oral dose. No differences were seen in hematologic parameters, body weight, or weight of the bursa of Fabricius. Birds given a high dose of malathion (230 mg/kg) displayed significant decreases in absolute and relative thymic and splenic weights (p ± 0.05). Significant changes were also seen in thymic and splenic histomorphometry (p ± 0.05). The high-dose group and, in some cases, the low-dose group (92 mg/kg) displayed significant histologic lesions. These findings indicate that a single dose of malathion, at the LD50 level (230 mg/kg) and occasionally at 40% of the LD50 level (92 mg/kg), is capable of inducing quantitative and qualitative changes in the lymphoid organs of the ring-necked pheasant that may affect immune function.
Survival of copper-exposed juvenile fathead minnows (Pimephales promelas) differs among allozyme genotypes
Authors: Schlueter Mark A. , Guttman Sheldon I. , Oris James T. , Bailer A. John
Published: March 2010

The effects of seven variable enzyme loci and multiple-locus heterozygosity on time to death (TTD) during an acute 96-h copper exposure were examined by two failure-time regression models. Allozymes for five enzyme loci (GPI-1*, GPI-2*, IDHP-1*, MDH-2*, and PGM*) were significantly related to TTD. Heterozygosity was not significantly related to TTD. Fish weight was found to have a negative relationship with TTD, larger fish having shorter TTD. This unusual relationship may have resulted from differential survivorship of individuals with sensitive and resistant alleles at the MDH-2* and the IDHP-1* loci. For the IDHP-1* locus the allele *a was associated with increased copper survivorship; however, it was also associated with small size. Conversely, the allele *a at the MDH-2* locus, which was present in higher frequency in larger fish, was associated with decreased survivorship. These results indicate that genetic selection for one characteristic may have a negative impact on other characteristics. Survivors of the copper exposure were genetically selected for copper resistance, resulting in the significant reduction in frequencies of several sensitive genotypes in the population. We conclude that monitoring population genetic structure and frequency changes of sensitive genotypes is a useful biomarker.
Fathead minnow (Pimephales promelas rafinesque) reproduction in outdoor microcosms: An assessment of the ecological effects of fish density
Authors: Shaw Jennifer L. , Maund Stephen J. , Marshall Stacey J. , Hill Ian R.
Published: March 2010

This study was part of a research program designed to evaluate fathead minnow (Pimephales promelas) reproduction in 17-m3 outdoor microcosms as a test system to investigate ecosystem-level impacts of toxicants. Sex ratios of fathead minnow (FHM) adults at stocking were manipulated to regulate the biomass and numbers of young-of-the-year (YOY) following reproduction. This study reports the effect of fish densities obtained from six different sex ratios on microcosm ecology that were compared to a fishless control during a 4.5-month period. Fish sampled during the study were representative of the actual population. Taxa collected from FHM stomachs were very diverse (16 groups) representing various communities and trophic levels. Bacillariophyta, filamentous algae, and macrophytes were the dominant food source; however, Crustacea, rotifers, chironomids, and other macroinvertebrates were also important. Effects on community structure were investigated using multivariate discriminant analysis. There were no fish density effects on zooplankton or benthic macroinvertebrate community structures. Microcosms with high FHM densities had fewer emerging chironomids, and phytoplankton levels were elevated. Phytoplankton taxa, which discriminated phytoplankton community structure differences between fish biomass groups, were also positively correlated with total phosphorus.
Further investigations of the etiology of subcutaneous neoplasms in native gizzard shad (Dorosoma cepedianum)
Authors: Jacobs Ann Durham , Ostrander Gary K.
Published: March 2010

Aspects of the etiology of subcutaneous spindle-cell neoplasms in feral gizzard shad (Dorosoma cepedianum) collected from Lake of the Arbuckles, Oklahoma, were investigated. Field collections of adult and juvenile gizzard shad were conducted to determine the prevalence and seasonality of neoplasms and site specificity of neoplasm-bearing fish. Overall neoplasm prevalence for adult gizzard shad was 22.1%; no juveniles exhibited neoplasms. Neoplasm occurrence did not appear seasonal. Neoplasm-bearing gizzard shad were found at all three sampling sites within Lake of the Arbuckles with similar neoplasm prevalence rates (Guy Sandy Creek 22.1%, Rock Creek, 17.9%, and Buckhorn Creek 22.4%). No gizzard shad (juvenile or adult) collected from Lake Carl Blackwell, Oklahoma, the reference site, exhibited neoplasms. Water, sediment, and shad liver tissue from Lake of the Arbuckles and the reference site were analyzed for total recoverable metals (cadmium, chromium, copper, nickel, and lead, by graphite furnace atomic absorption). Chromium, copper, and nickel were found in the water samples at concentrations of >1 to 8.6 μg/L. Low concentrations (>1 to 13.6 μg/g wet weight) of all the metals were found in the sediment and liver tissue from both sites. Heavy metal contamination does not appear linked to neoplasm occurrence. To determine if a nonbacterial infectious agent was responsible for tumor formation, cell-free neoplasm homogenates were injected into healthy rainbow trout. Neoplasms were not transmitted into rainbow trout. The etiology of these neoplasms remains unknown.
Biodegradation of no. 2 diesel fuel in the vadose zone: A soil column study
Authors: Widrig David L. , Manning John F.
Published: March 2010

Packed soil columns were used to simulate and investigate in situ biological remediation of soil contaminated with diesel fuel. We investigated and evaluated several operating strategies, including continuous flooding of the column soil with nutrient solution, and periodic operating cycles consisting of flooding followed by draining and aeration. The objectives were (a) to determine the extent of diesel fuel degradation in soil columns under four operating conditions (biologically inhibited control; continuous saturation with nitrogen and phosphorus amendments; periodic operation, consisting of flooding with nitrogen and phosphorus, followed by draining and forced aeration; and periodic operation, consisting of flooding with nitrogen, phosphorus, and calcium and magnesium amendments, followed by draining and forced aeration); (b) to evaluate CO2 production and oxygen consumption as indicators of biodegradation; (c) to monitor hydraulic conductivity under different operating strategies; and (d) to examine the system requirements for nitrogen and phosphorus. Our results showed that periodic operation promoted higher rates of biodegradation of diesel fuel in soil and minimized the use of water containing nutrient amendments, and consequently the possible need to collect and treat such water. We believe that monitoring CO2 and O2 levels in situ may provide a means of optimizing the timing of flooding and aeration events to increase degradation rates. Results of this laboratory study will aid in improving the design and operation of field-scale bioremediation systems.
Laboratory methods for volatile organic compounds evolved in mineralization studies
Authors: Hickey William J. , Arnold Scott M. , Moran Bridget N.
Published: March 2010

A system to study mineralization of volatile organic compounds (VOCs) was developed using commercially available solid-phase VOC traps and impingers to collect CO2 as well as VOCs breaking out from the solid-phase trap. The efficiencies of VOC traps containing activated charcoal (AC) or graphitized carbon black (GCB) for absorbing [14C]trichloroethylene ([14C]TCE) and 14CO2 were evaluated, and approaches for minimizing VOC losses from reaction vessels were established. Mass balances showed AC and GCB absorbed similar amounts of [14C]TCE. However, GCB had no detectable 14CO2 retention, whereas AC absorbed about 7% of the 14CO2. Because 14CO2 absorption could influence the interpretation of mineralization experiments, GCB was concluded to be the better VOC-trapping matrix.
Environmental fate of methylcyclopentadienyl manganese tricarbonyl
Authors: Garrison Arthur W. , Lee Wolfe N. , Swank Robert R. , Cipollone Mark G.
Published: March 2010

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been proposed as an octane booster for unleaded gasoline; such use could result in ecological and human exposure through surface water and groundwater ecosystems. To evaluate the environmental risks from MMT, its environmental fate constants and transformation pathways must be known. Constants for physical parameters that would likely influence MMT fate were collected from the literature or calculated; the compound's octanol/water partition coefficient and water solubility were determined in the laboratory. Experiments were designed to screen MMT for transformation pathways that are significant over environmentally short time frames. The MMT was found to be fairly stable in the dark in aquifer materials and sediments at various Eh levels; half-lives ranged from 0.2 to 1.5 years in aquifer materials at 25°C. (These matrices were not optimized for biodegradation.) On the other hand, MMT photolyzes rapidly in distilled water; its half-life in midday sunlight in water is approximately 1 min and the disappearance quantum yield is 0.13. Photodegradation products were identified as cyclopentadiene, methyl cyclopentadiene, carbon monoxide, and a manganese carbonyl that readily oxidized to trimanganese tetroxide.
Metal and arsenic impacts to soils, vegetation communities and wildlife habitat in southwest Montana uplands contaminated by smelter emissions: I. Field evaluation
Authors: Galbraith Hector , Lejeune Katherine , Lipton Joshua
Published: March 2010

Concentrations of arsenic and metals in soils surrounding a smelter in southwest Montana were correlated with vegetative community structure and composition and wildlife habitat quality. Soils in the uplands surrounding the smelter were highly enriched with arsenic and metals. Concentrations of these analytes decreased with distance from the smelter and with soil depth, suggesting that the smelter is the source of the enrichment. In enriched areas, marked modifications to the native vegetation community structure and composition were observed. These included replacement of evergreen forest with bare unvegetated ground; species impoverishment and increased dominance by weed species in grasslands; and reductions in the vertical complexity of the habitat. Significant negative correlations existed between soil arsenic and metals concentrations and the extent of vegetative cover and the vertical diversity of plant communities. Loss of vegetative cover in the affected areas has been accompanied by reductions in their capacity to support indigenous wildlife populations.
Metal and arsenic impacts to soils, vegetation communities and wildlife habitat in southwest montana uplands contaminated by smelter emissions: II. Laboratory phytotoxicity studies
Authors: Kapustka Lawrence A. , Lipton Joshua , Galbraith Hector , Cacela Dave , Lejeune Katherine
Published: March 2010

Vegetation communities on metal- and arsenic-contaminated uplands surrounding a smelter in southwest Montana have been eliminated or highly modified. Laboratory toxicity tests were performed using site soils from the impacted areas to determine whether the soils limit the ability of plants to establish and grow. The germination and growth of alfalfa, lettuce, and wheat in impacted area soils was compared to germination and growth of the three species in reference soils. The degree of phytotoxicity was quantified using a species-endpoint toxicity score calculated on the magnitude of difference between germination and growth of plants in impacted and reference soils. The impacted soils exhibited substantial toxicity to plants: 5% of the sites were severely phytotoxic, 55% were highly phytotoxic, 10% were moderately phytotoxic, 20% were mildly phytotoxic, and 10% were nontoxic. Root growth was consistently the most affected endpoint (18 of 20 impacted soils) and reduction in root length and mass was observed. Correlation and partial correlation analysis was used to evaluate the causes of phytotoxicity. Concentrations of As, Cu, and Zn and, to a lesser extent, Pb and Cd were found to be positively correlated with phytotoxicity.
Comparative acute toxicity of a synthetic mine effluent to Ceriodaphnia dubia, larval fathead minnow and the freshwater mussel Anodonta imbecilis
Authors: Masnado Robert G. , Geis Steven W. , Sonzogni William C.
Published: March 2010

To determine if water quality-based effluent limitations recommended for a proposed discharger would provide adequate protection of aquatic life, site-specific acute toxicity tests were performed. The proposed discharger studied was a mine to be located in northern Wisconsin. The mine's discharge would flow into the Flambeau River, a relatively pristine river that harbors endangered freshwater mussels. The toxicity effects of synthetic effluents, representing a mixture of five different metals under contrasting conditions of hardness, were tested on several different organisms. Results indicated that Ceriodaphnia dubia exhibited a much greater sensitivity to various mixtures of cadmium, hexavalent chromium, copper, nickel, and zinc than did either larval fathead minnows (Pimephales promelas) or the freshwater mussel Anodonta imbectlis. Mixtures of metals at the permitted discharge levels of individual metals were also found to be consistently toxic to C. dubia. Because C. dubia was found to be much more sensitive than A. imbecilis, an effluent safe for C. dubia should also be safe for A. imbecilis and the physiologically similar endangered mussels found in the river. Based on such testing, aquatic life toxicity-testing conditions and criteria suggested for the National Pollution Discharge Elimination System (NPDES) permit should be protective of C. dubia and, hence, other aquatic life such as endangered mussels. Overall, effluent limitations for proposed dischargers need to be based on the combined effect of complex effluents. Aquatic toxicity testing using synthetic effluents that approximate the expected discharge characteristics provides a viable approach to determining the limits for proposed dischargers of multiple pollutants.
Effect of the input pathway on the distribution of 1,2,3,4,7-pentachlorodibenzo-p-dioxin in an aquatic mesocosm
Authors: Friesen Kenneth J. , Segstro Mark D. , Webster G.R. Barrie , Muir Derek C.G.
Published: March 2010

The effect of the input pathway on the distribution of 1,2,3,4,7-pentachlorodibenzo-p-dioxin (P5CDD) in small-pond mesocosms was determined by introducing 14C-labeled dioxin (468 μg) into the water sorbed to sediment particles and by a surface sprayover in a water-miscible organic solvent. Rates of clearance from the water column were rapid and unrelated to the input method in either case, with pseudo-first-order half-lives (t1/2) of 0.38 ± 0.19 d (r2 = 0.81) and 0.57 ± 0.08 d (r2 = 0.98) for the particle-sorbed and sprayover applications, respectively, over the first 24 h after input. However, redistribution pathways were strongly influenced by the route of entry of P5CDD into the ecosystem. Ponds receiving a sprayover of P5CDD showed higher concentrations of the dioxin in surface microlayers with larger amounts also collected in air above these ponds. Concentrations of P5CDD in the bottom sediments of these ponds were significantly lower (0.6 ng/g dry weight) compared to concentrations in sediments of ponds receiving a sediment slurry input (1.2 ng/g dry weight). Evaluation of the results using several fugacity-based aquatic-fate models indicated that when P5CDD entered the aquatic ecosystem in the sorbed state, sedimentation dominated its redistribution. However, with a sprayover input, film-to-water transfer, partitioning and deposition to bottom sediment, volatilization, and photolytic degradation in surface microlayers were important processes affecting the fate of P5CDD in the mesocosm.