bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity of aspen wood leachate to aquatic life: Laboratory studies
Authors: Taylor Barry R. , Goudey J. Stephen , Carmichael N. Bruce
Published: March 2010

Trembling aspen (Populus tremuloides Michx.), a common hardwood tree throughout Canada, is being harvested at increasing rates for use in paper and building materials. Piles of aspen logs have been observed to produce a dark, watery, acutely toxic leachate. A laboratory study was undertaken to elucidate the nature, strength, and persistence of aspen leachate toxicity and the chemical composition of the leachate. Leaching from aspen chips in the laboratory was rapid, with 1% mass loss in the first 24 h. Another 2 weeks of immersion was necessary to remove all remaining leachable material (3% total). Fresh aspen leachate derived from a 1:9 wood-water mixture (35 d immersion) was characterized by amber color, low pH (4.0), extremely high BOD (>2,600 mg/L), and high conductivity (1140 μS/cm). The leachate was rich in phenols (30 mg/L), organic carbon (2,480 mg/L), and organic nitrogen (13 mg/L). Median acutely toxic concentrations of leachate were consistently 1 to 2% of full strength for trout and Daphnia. Inhibition of bacterial metabolism began at concentrations below 0.3%. Leachate was less toxic to plant life but inhibited algal growth at concentrations of 12 to 16%. Toxicity of aspen leachate persisted at the same level as in fresh leachate for more than 2 months unless artificial aeration was provided. Persistence was even greater at low temperature (5°C). Aged leachate underwent a transition marked by a rise in pH and dissolved oxygen concentration, a small decline in conductivity, and a color change, from amber to black. Toxicity declined abruptly when the supply of labile toxicants was exhausted, but it sometimes increased again from the products of microbial metabolism. Oxygen depletion, low pH, and phenolic compounds contribute to the toxicity of aspen leachate, but much of the toxic effect must be attributed to other, unidentified constituents.
Gas chromatography-mass spectrometry analysis of the herbicide clopyralid in differentially cultivated soils
Authors: Schütz Stefan , Weißbecker Bernhard , Hummel Hans E.
Published: March 2010

The herbicide clopyralid offers a high selectivity in thistle control using low application rates. Contradictory results in soil leaching experiments using this herbicide indicate the need for a reliable procedure for trace analysis of clopyralid. The problem of poor extraction efficiency from soil that is rich in humic substances was solved by ultrasound-enhanced alkaline extraction. Analysis of the extract was performed by gas chromatography-mass spectrometry after derivatization with pentafluorobenzylbromide in an ultrasound-enhanced phase-transfer catalytic reaction. Tetrabutylammoniumbromide served as a phase-transfer catalyst. For improving analytical reliability, 2,5-dichlorobenzoic acid was used as an internal standard. The achieved detection (1 μg/kg = 1 ppb) and quantification (10 μg/kg) limits of clopyralid in soil were appropriate for determining the degradation behavior in herbicide-treated soils. The half-life of clopyralid in two differentially cultivated soils was determined in laboratory trials. Uncultivated soil that was rich in humic acids showed a higher half-life than cultivated soil.
Effects of low ph on the uptake and distribution of 54Mn(II) in brown trout (Salmo trutta)
Authors: Rouleau Claude , Tjälve Hans , Gottofrey James
Published: March 2010

Goups of seven fish were exposed for 21 d to 0.1 μg 54Mn L−1 at pH 5.3 and 7.5. At the end of the experiment, the whole-body 54Mn concentration offish held in water at pH 5.3 was significantly higher (1.7 times) compared to fish held at pH 7.5. A similar increase was observed in viscera, brain, and eyes. These results suggest that higher Mn levels found in fish living in acidic waters may not only depend on the higher total Mn concentrations usually found in these waters.
Use of Rodeo® and X-77® spreader to control smooth cordgrass (Spartina alterniflora) in a southwestern washington estuary: 1. Environmental fate
Authors: Paveglio Fred L. , Kilbride Kevin M. , Grue Christian E. , Simenstad Charles A. , Fresh Kurt L.
Published: March 2010

A 1-ha plot with smooth cordgrass (Spartina alterniflora) at three locations in Willapa Bay, a southwestern Washington estuary, was aerially treated with 4.7 L/ha Rodeo® and 0.9 L/ha X-77® Spreader to determine the fate of the herbicide formulation. Rates of spray deposit on filter pads placed over treated intertidal mudflats did not differ among locations for glyphosate and aminomethylphosphonic acid (AMPA); however, deposit rates for nonylphenol polyethoxylates (NPEO) did differ among locations. Glyphosate concentrations in sediment cores from treated mudflats declined 51 to 72% during 119 days posttreatment (DPT); NPEO concentrations in sediment declined (42%) between spray day and 14 DPT. The highest concentrations of glyphosate, AMPA, and NPEO in seawater were found in off-site samples collected from the leading edge of the first high tide after application. Glyphosate and AMPA concentrations in depth-integrated seawater samples declined 73 and 42%, respectively, between the first high tide immediately following application and the second high tide at 1 DPT. Glyphosate concentrations in Spartina stems from treated plots declined 91 to 99% between 1 and 28 DPT; whereas, AMPA declined (86 and >96%) during this period. Comparison of maximum concentrations for glyphosate in seawater from this study with acute toxicity values in the literature indicates that under worst-case conditions direct effects to aquatic organisms would not be likely.
Toxicological benchmarks for screening contaminants of potential concern for effects on freshwater biota
Authors: Suter G. W.
Published: March 2010

An important early step in the assessment of ecological risks at contaminated sites is the screening of chemicals detected on the site to identify those that constitute a potential risk. Part of this screening process is the comparison of measured ambient concentrations to concentrations that are believed to be nonhazardous, termed “benchmarks.” This article discusses 13 methods by which benchmarks may be derived for aquatic biota and presents benchmarks for 105 chemicals. It then compares them with respect to their sensitivity, availability, magnitude relative to background concentrations, and conceptual bases. Although some individual values can be shown to be too high to be protective and others are too low to be useful for screening, none of the approaches to benchmark derivation can be rejected without further definition of what constitutes adequate protection. The most appropriate screening strategy is to use multiple benchmark values along with background concentrations, knowledge of waste composition, and physico-chemical properties to identify contaminants of potential concern.
Inorganic polyphosphates in the developing freshwater sponge Ephydatia muelleri: Effect of stress by polluted waters
Authors: Imsiecke Georg , Münkner Jessica , Lorenz Bernd , Müller Werner E. G. , Schroder Heinz C. , Bachinski Nilza
Published: March 2010

Relatively high amounts of inorganic polyphosphates (approximately 55 μg of polyphosphate/g of wet weight) were found in the freshwater sponge Ephydatia muelleri, particularly in the gemmules (260 μg/g). Here we report that the polyphosphate content of this sponge changes during development and in response to adverse environmental conditions. Germination and hatching of gemmules of E. muelleri is accompanied by a strong decrease (by 94% at day 2) in polyphosphate level and a rise in exopolyphosphatase activity. On the other hand, induction of gemmulogenesis by theophylline results in an increase (by 61%) in polyphosphate content of sponge tissue. An increase in polyphosphate content and a decrease in exopolyphosphatase activity also occur during tissue regression when hatched sponges are exposed to polluted water from river. Nonionic organic compounds extracted from this water were identified as contaminants causing a rise in polyphosphate content of E. muelleri. The results show that measurement of polyphosphate level may be a promising method to detect responses of the freshwater sponge to polluted waters.
Effects of a nonionic surfactant (C14–15AE-7) on aquatic invertebrates in outdoor stream mesocosms
Authors: Gillespie William B. , Rodgers John H. , Crossland Norman O.
Published: March 2010

Responses of aquatic invertebrates to a C14–15 linear alcohol ethoxylate (LAE) nonionic surfactant with an average of seven ethylene oxide units per mole of alcohol were evaluated in outdoor stream mesocosms. Two experiments were carried out to evaluate responses of aquatic invertebrates to 28- and 30-d exposures in eight stream mesocosms. Changes in benthic invertebrate densities and in invertebrate drift were monitored during pretreatment, treatment, and posttreatment periods. In Experiment 1, mean measured concentrations of surfactant were 0.08, 0.16, and 0.33 mg LAE/L. In Experiment 2, mean measured concentrations were 0.11, 0.28, and 0.55 mg LAE/L. In each experiment, there were two treated streams at each surfactant concentration and two untreated streams that served as controls. No significant effects (p > 0.05) on population densities of Copepoda, Cladocera, Chironomidae, Nematoda, or Annelida were observed in either experiment. Moreover, no effects were detected on the numbers of any of these organisms collected in drift nets. However, there was a significant decrease (p ≤ 0.05) in the densities of Simuliidae at surfactant concentrations ≥0.16 mg LAE/L. This was accompanied by an increase in the numbers of Simuliidae collected in drift nets. Based on these results, the no-observed-effect concentration for aquatic invertebrates was 0.08 mg LAE/L, and the lowest-observed-effect concentration was 0.16 mg LAE/L.
Lyophilization of thylakoids for improved handling in a bioassay
Authors: Zimmermann Gitta M. , Kramer Gerard N. , Schnabl Heide
Published: March 2010

The thylakoid bioassay is used to determine the effect of herbicides in water. To avoid isolation for each bioassay, lyophilization of thylakoids for continuous, reproducible supply as bioassay material is descibed. This technique maintains the photosynthetic activity after lyophilization at 82 ± 9% (n = 5) of its original level.
Toxicity of organic mixtures containing cyanogenic toxicants
Authors: Chen Chung-Yuan , Huang Chi-Feng
Published: March 2010

In this study we evaluated the joint actions of cyanogenic toxicants with other organic chemicals using Microtoxx® tests. Experimental results indicated that greater than additive effect seldom occurred when these chemicals were mixed with nonreactive toxicants. However, the likelihood of synergistic effects exceeded 30% when reacting with a reactive chemical. Among the cyanogenic toxicants investigated in this study, malononitrile, lactonitrile, and α-hydroxy-isobutyronitrile have an approx. 50% likelihood of acting via synergism mode with other reactive toxicants. On the other hand, the joint actions related to acetonitrile and allyl cyanide are either additive or less than additive. Moreover, the likelihood of encountering synergistic effects markedly increases if the slopes of the dose–response curves for the two chemicals tested are small. Therefore, slope and certain characteristics of a chemical structure can apparently be used as indices to assess the potential hazard for a specific organic mixture. Furthermore, the complex joint action exerts a certain deterministic influence over the joint action mode of cyanogenic toxicants. This type of joint action, which quite frequently leads to an obvious antagonistic or even detoxification phenomena, could have some useful toxicological and pharmacological applications. Lastly, estimating the mixture toxicity on the basis of the concentration addition model is not always appropriate considering the high percentage of cases in this study showing synergism.
Effects of exposure to an organophosphorus pesticide on the behavior and use of cover by captive starlings
Authors: Fryday Steven L. , Hart Andrew D. M. , Langton Stephen D.
Published: March 2010

It has been suggested that reduced behavioral activity of birds exposed to anticholinesterase pesticides could bias measures of exposure in field studies if the worst-affected individuals were underrepresented in samples collected by shooting or netting. To assess the likely scale of such biases, European starlings (Sturnus vulgaris) were housed in large aviaries containing simulated bushes made from natural vegetation. Each bird was given a near-lethal dose of the organophosphorus pesticide chlorfenvinphos, and the proportion of time spent in and out of cover was recorded before and after treatment. Use of cover by exposed birds increased significantly 0 to 7 h after treatment, whereas feeding and flying activity decreased. On the following day, there was little difference in the use of cover by exposed and control birds. Mathematical models were used to estimate the effect of these behavioral changes on the sampling of birds from wild populations. The results confirm the potential for sampling bias to occur after acute pesticide exposure. This bias is reduced in samples taken over 24 h after exposure, but delayed samples are unlikely to be representative of cholinesterase (ChE) inhibition at the time of maximal effect. When poisoned birds seek cover, it is more difficult to find casualties in field trials and the probability that dead birds will be found and recorded in wildlife casualty monitoring schemes is reduced. We conclude that considerable caution is required in using ChE activity as an indicator of exposure in avian field trials.
Effects of different formulations of granular pesticides on birds
Authors: Stafford Tamara R. , Best Louis B. , Fischer David L.
Published: March 2010

Fensulfothion was formulated on granular pesticide carriers to evaluate the effects of carrier type (silica, clay, and corncob), pesticide load per granule (½, ⅛, and 1/32 of the LD50), granule size (0.2 to 0.6 and 1.0 to 1.4 mm), and granule color (white and blue) on avian risk from granular pesticides. Carrier type and pesticide load per granule were evaluated in a separate experiment from granule size and color. In both experiments, captive house sparrows (Passer domesticus) were offered the granular pesticide formulations in bands on soil surfaces. Bird behavior, body weight, survival, and brain and plasma cholinesterase activity were used to assess pesticide exposure. Silica and clay carrier types posed a greater risk to birds than corncob granules. Exposure also was greater with a higher pesticide load per granule. Findings were inconclusive regarding the effect of granule size and color on avian exposure to granular pesticides. Precipitation seemed to increase the possibility of dermal exposure to the pesticide. It is important to consider factors in addition to those used currently by the U.S. Environmental Protection Agency when evaluating the risk to birds from granular pesticides.
Predicting the relative toxicity of metal ions using ion characteristics: Microtox® bioluminescence assay
Authors: McCloskey John T. , Newman Michael C. , Clark Sue B.
Published: March 2010

Quantitative structure—activity relationships have been used to predict the relative toxicity of organic compounds. Although not as common, ion characteristics have also proven useful for predicting the relative toxicity of metal ions. The purpose of this study was to determine if the relative toxicity of metal ions using the Microtox® bioassay was predictable using ion characteristics. Median effect concentrations (EC50s) were determined for 20 metals in a NaNO3 medium, which reflected freshwater speciation conditions, using the Microtox bacterial assay. The log of EC50 values was modeled using several ion characteristics, and Akaike's Information Criterion was calculated to determine which ion characteristics provided the best fit. Whether modeling total ion (unspeciated) or free ion (speciated) EC50 values, the one variable which best modeled EC50s was the softness index (σp, i.e., [coordinate bond energy of the metal fluoride — coordinate bond energy of the metal iodide]/[coordinate bond energy of the metal fluoride]), while a combination of χ2mr (χm = electronegativity, r = Pauling ionic radius) and |log KOH| (absolute value of the log of the first hydrolysis constant, KOH for Mn+ + H2O → MOHn−1 + H+) was the best two-variable model. Other variables, including ΔE0 and χ2mr (one-variable models) and (ΔN/ΔIP, ΔE0) and (χ2mr, Z2/r) (two-variable models), also gave adequate fits. Modeling with speciated (free ion) versus unspeciated (total ion) EC50 values did not improve fits. Modeling mono-, di-, and trivalent metal ions separately improved the models. We conclude that ion characteristics can be used to predict the relative toxicity of metal ions whether in freshwater (NaNO3 medium) or saltwater (NaCl medium) speciation conditions and that this approach can be applied to metal ions varying widely in both valence and binding tendencies.
Statistical implications of end-point selection and inspection interval in the Daphnia reproduction test—A simulation study
Authors: Ratte Hans Toni
Published: March 2010

A general simulation approach was developed for validating biotest end points in the Daphnia reproduction test. Various toxic-effect scenarios, sample sizes, and inspection regimes were used to study the behavior and robustness of different end points. The intrinsic rate of natural increase (IR) and the capacity for increase (CI) were estimated because of their ecological significance. Both parameters were compared to conventionally chosen end points, the offspring number per female (ON) and the percent mortality (MO). The IR appeared to be the most sensitive end point among the different toxic-effect scenarios. In particular, effects on the age at first reproduction, which are highly relevant in population dynamics, were integrated. In general, the CI was as sensitive as the IR. However, the CI tends to overestimate the first brood. In contrast to ON and MO, both the IR and CI responded sensitively to the inspection regime. The IR was found to require daily recording of reproduction and mortality events, at least until the first broods appeared. Whereas the value of the CI remained questionable, from a statistical and ecological viewpoint the IR appeared to be superior.
Evaluation of metals in marine and freshwater surficial sediments from the environmental monitoring and assessment program relative to proposed sediment quality criteria for metals
Authors: Leonard Edward N. , Ankley Gerald T. , Hoke Robert A.
Published: March 2010

Surficial sediments collected from Lake Michigan (N = 46) and the Virginian Province of the east coast of the U.S. (N = 131) by the Environmental Monitoring and Assessment Program (EMAP) of the U.S. Environmental Protection Agency (EPA) were evaluated relative to a proposed approach to sediment quality criteria (SQC) for five metals (copper, cadmium, zinc, nickel, and lead). Concentrations of acid‒volatile sulfide (AVS), simultaneously extracted metals (SEM) from the AVS extraction, total metals, and total organic carbon were measured in the sediments. Interstitial pore‒water concentrations of the five metals also were measured in the freshwater sediment samples. Overall, 91% of 131 surficial marine sediments and 50% of 46 surficial freshwater sediments contained detectable AVS. In 93 of the marine sediments the concentrations of AVS were greater than total SEM (molar sum of copper, cadmium, zinc, nickel, and lead) indicating a low probability of bioavailable metal. In contrast, 91% of the surficial freshwater samples contained greater concentrations of total SEM than AVS. However, pore‒water concentrations of the five metals in the freshwater samples were uniformly low and never exceeded 0.3 toxic units based on an additive toxicity model that utilized final chronic values from EPA water quality criteria documents for the five metals. These predictions of minimal metal bioavailability in the EMAP samples were consistent with a general lack of toxicity in laboratory assays with the sediments and with the fact that they had been collected predominantly from ostensibly uncontaminated sites.
Parameters affecting the desorption of hydrophobic organic chemicals from suspended sediments
Authors: Borglin Sharon , Wilke Amy , Jepsen Rich , Lick Wilbert
Published: March 2010

Recent work has demonstrated that both the adsorption and desorption of hydrophobic organic chemicals to sediments and soils can be quite slow and that chemical equilibrium may not be a good approximation in many real situations. By means of long‒term batch experiments, this has been recently and clearly shown for the adsorption of hexachlorobenzene and three polychlorinated biphenyls to suspended sediments. In the present study, long‒term desorption experiments are performed with three hydrophobic organic chemicals (hexachlorobenzene and two polychlorinated biphenyls) and suspended sediments. Desorption times are on the order of a month to several years. It is shown that the desorption rates are dependent on the particle/floc size and density distributions, the type of water, the amount of organic carbon in the sediments, the time of adsorption before desorption, and the chemical partition coefficient. It is also shown that a simple chemical diffusion model with an effective diffusion coefficient dependent on the porosity of the particle/floc, the organic content of the sediments, and the chemical partition coefficient, along with proper consideration of particle/floc size and density distributions is sufficient to explain the experimental results.
Heavy metals in laughing gulls: Gender, age and tissue differences
Authors: Gochfeld Michael , Belant Jerrold L. , Shukla Tara , Benson Tom , Burger Joanna
Published: March 2010

We examined concentrations of lead, cadmium, mercury, manganese, selenium, and chromium in feathers, liver, kidney, heart, and muscle of known-aged laughing gulls (Larus atricilla) that hatched in Barnegat Bay, New Jersey and were collected at John F. Kennedy International Airport, New York 1 to 7 years later. Concentrations differed significantly among tissues, and “tissue” entered all the regression models explaining the greatest variation in metal levels. Age of bird contributed significantly to the models for lead, cadmium, selenium, and chromium. Although there were significant gender differences in all body measurements except wing length, there were few differences in metal levels. Males had significantly higher lead levels in feathers, and females had significantly higher selenium levels in heart and muscle tissue. For lead, 3-year olds had the highest levels in the heart, liver, and kidney, and levels were lower thereafter. Mercury levels in feathers and heart decreased significantly with age. Cadmium levels increased significantly with age for feathers, heart, liver, and muscle, although there was a slight decrease in the 7-year olds. Selenium levels decreased significantly with age for all tissues. Chromium levels increased with age for liver and heart.
Effect of the fungicide clotrimazole on the bioconcentration of benzo[a]pyrene in gizzard shad (Dorosoma cepedianum): In vivo and in vitro inhibition of cytochrome P4501A activity
Authors: Levine Steven L , Czosnyka Hillary , Oris James T
Published: March 2010

Clotrimazole was found to inhibit in vivo and in vitro hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity in gizzard shad (Dorosoma cepedianum). Gizzard shad pretreated with 50 mg clotrimazole/kg and then exposed for 1 or 3 d to benzo[a]pyrene (BaP) (0.86 μg/L) had significantly lower EROD activity compared to fish that were exposed to BaP alone. Following 1 and 3 d of BaP exposure, groups pretreated with clotrimazole had a 14- and 4-fold decrease in EROD activity and had biocon-centrated 8 and 11 times more parent BaP, respectively, compared to groups exposed to BaP alone. Addition of clotrimazole to BaP-induced microsomes produced a type II binding spectrum and was an effective in vitro inhibitor of EROD activity. The median inhibitory concentration for EROD activity was 0.51 μM clotrimazole. Kinetic and spectral experiments suggest that the mechanism of inhibition by clotrimazole is noncompetitive. Reduction in the rate of oxidative BaP metabolism is hypothesized to result from noncompetitive inhibition of cytochrome P4501A and other P450 enzymes that metabolize BaP.
Enhanced copper adsorption and morphological alterations of cells of copper-stressed Mucor rouxii
Authors: Gardea-Torresdey Jorge L , Cano-Aguilera Irene , Webb Robert , Gutierrez-Corona Félix
Published: March 2010

Fungi are ubiquitous and can become dominant in metal-polluted habitats. Some fungal strains are tolerant to metal toxicity. The presence of a high copper concentration in the culture medium induced morphological changes in the copper-tolerant strain of Mucor rouxii. Copper binding by strains of M. rouxii cultured at a trace (1.6 × 10−3 mM) copper concentration was less effective than those cultured at a high (3.2 mM) copper concentration. These experiments were performed at an optimum time of 30 min and a pH of 5 for Cu2+ binding. Our results suggest that a passive metal-binding mechanism makes the majority of total copper binding. These preliminary findings suggest that the presence of high levels of copper in the culture medium allow the development of chemical functional groups on the fungal surface, which led to an enhanced copper-binding ability and induced important morphological changes in M. rouxii.
Effects of ion pairing with calcium and magnesium on selenate availability to higher plants
Authors: Parker David R , Tice Kathy R , Thomason David N
Published: March 2010

The effects of solution speciation on the bioavailability of trace metals are well documented, but the role of speciation in the bioavailability of oxyanionic trace elements that may form significant ion pairs with Ca and Mg in saline media has not been investigated. We assessed the effects of such ion pairing on the availability of selenate to representative monocotyledonous and dicotyledonous higher plants. Formation constants for the CaSO 04 and CaSeO 04 ion pairs were experimentally determined using a Ca2+ ion-selective electrode. The published value of 102,3 for CaSO 04 formation was confirmed, but the value of 1027 for CaSeO 04 was found to be in error; a value of 102,0 is proposed here as the correct formation constant. Five solution culture experiments were conducted using alfalfa (Medicago sativa L.) or tall wheatgrass (Elytrigia pontica [Podp.] Holub) with treatments consisting of NaSeO4 levels in combination with various levels of MgCl2 or CaCl2. Both shoot Se concentrations and whole-plant Se contents were highly correlated with the free SeO2−4 activity but were poorly correlated with the sum of the free ion plus Ca and Mg ion pair species. Thus, we have shown, for the first time, that the free ion model of trace metal bioavailability is also valid for oxyanions that form complexes with Ca and Mg in saline media but that this conclusion hinges critically on the accuracy of the pertinent formation constants.
Declining bioavailability and inappropriate estimation of risk of persistent compounds
Authors: Kelsey Jason W , Alexander Martin
Published: March 2010

Earthworms ( Eisenia foetida) assimilated decreasing amounts of atrazine, phenanthrene, and naphthalene that had been incubated for increasing periods of time in sterile soil. The amount of atrazine and phenanthrene removed from soil by mild extractants also decreased with time. The declines in bioavailability of the three compounds to earthworms and of naphthalene to bacteria were not reflected by analysis involving vigorous methods of solvent extraction; similar results for bioavailability of phenanthrene and 4-nitrophenol to bacteria were obtained in a previous study conducted at this laboratory. We suggest that regulations based on vigorous extractions for the analyses of persistent organic pollutants in soil do not appropriately estimate exposure or risk to susceptible populations.
Magnitude and persistence of herbicide residues in farm dugouts and ponds in the Canadian prairies
Authors: Grover Raj , Waite Don T , Cessna Allan J , Nicholaichuk Wally , Irvin Don G , Kerr Lorne A , Best Kelly
Published: March 2010

Farm ponds or dugout waters were monitored for residues of seven major herbicides used in the Canadian prairies from fall of 1987 to spring of 1989. The frequencies of confirmed detection of herbicides in water samples, depending on the time of sampling, in decreasing order were: 2,4-dichlorophenoxyacetic acid (2,4-D; 93–100%), diclofop (46–95%), bromoxynil (50–85%), 4-chloro-2-methyl-phenoxyacetic acid (MCPA; 33–70%), triallate (28–63%), dicamba (17–55%), and trifluralin (0–18%). The corresponding frequencies of quantifiable residues (≥0.05 μg/L) were lower, ranging from 75 to 86% for 2,4-D to 0 to 7% for dicamba. Median residues in all water samples were near or below the quantification limits of 0.05 μg/L. Maximum residues varied widely and were (μg/L): trifluralin (not detectable [ND]–0.11), bromoxynil (0.27–0.33), dicamba (ND–11.2), triallate (0.05–0.87), MCPA (0.12–1.97), 2,4-D (0.64–2.67), and diclofop (0.27–3.47). Maximum residues were seasonal and declined to near or below detection limits by the following sampling time. Median values were two to three orders of magnitude less than the corresponding maximum allowable concentration and interim maximum allowable concentration guidelines for drinking water in Canada and the United States. Maximum values were also less than these guidelines. Only the maximum values for residues of MCPA and 2,4-D approached the guidelines for these herbicides in water used for irrigation.
Precision and sensitivity of a seven-day growth and survival toxicity test using the west coast marine mysid crustaceanHolmesimysis costata
Authors: Hunt John W , Anderson Brian S , Turpen Sheila L , Englund Matthew A , Piekarski Witold
Published: March 2010

A 7-d growth and survival toxicity test using the west coast marine mysid crustacean Holmesimysis costata (Holmes) was evaluated to determine test precision and sensitivity. The intralaboratory coefficient of variation (CV) among six reference toxicant test median lethal concentrations (LC50s) was 25%, whereas the mean intralaboratory CV for side-by-side effluent test LC50s was 7%. The mean intralaboratory CV for the concentration at which growth was inhibited by 25% (IC25) was 19%. Interlaboratory CVs for effluent LC50s averaged 14%, whereas variation among growth IC25s averaged 15%. Test precision and sensitivity compared favorably with literature values for a number of commonly used toxicity tests and chemical methods. Toxicity increased slightly with increased mysid exposure from 4 to 7 d (mean effluent LC50s of 9.9% for 4 d of exposure and 7.5% for 7 d), and more significantly from 7 to 24 d (zinc LC50 values were 50 μg/L and 7.8 μg/L for concurrent 7-d and 24-d tests). Although growth was a less sensitive endpoint than survival in tests with individual chemicals (zinc and sodium azide), growth was the more sensitive endpoint in seven of nine tests with complex effluents. Seventy-five percent of tests conducted at all participating laboratories met protocol test acceptability criteria (n = 40).
Effects of acute 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure on plasma thyroid and sex steroid hormone concentrations and estrogen receptor levels in adult great blue herons
Authors: Janz David M , Bellward Gail D
Published: March 2010

Adult great blue herons (Ardea herodias) were exposed intraperitoneally to a single dose of 20 μg/kg body weight of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and sacrificed after 14 d. Approximately 1.9% of the total TCDD dose was measured in the liver. No differences were found in liver weight or liver to body weight ratio between control and TCDD-treated birds. Hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity was induced sixfold above control activities in TCDD-exposed herons (p < 0.001). Plasma total T4 concentration was significantly elevated in TCDD-exposed herons (p < 0.05). The TCDD treatment had no effect on plasma total T3 levels, or on the plasma T3 to T4 ratio. No effect of this TCDD exposure was found on plasma 17β-estradiol or testosterone concentrations, or on hepatic estrogen receptor affinities and concentrations is male or female herons.
Advances in forensic toxicology for establishing causality between Great Lakes epizootics and specific persistent toxic chemicals
Authors: Gilbertson Michael
Published: March 2010

Populations of fish, wildlife, and humans in the Great Lakes basin have been injured during this century by exposures to organochlorine pollutants. The evidence presented by scientists working on these outbreaks of chemically induced disease has been received with scepticism among officials, who have expressed a desire for a “proven” cause and effect before further costly regulatory and remedial action is taken. Scientists have adapted epidemiological criteria to infer causal relationships between the injury and exposures to specific chemicals. These forensic statements are different from traditional toxicological statements about potential effects. There is a priority need to institutionalize this methodology within governments to complement established risk assessment techniques.
The use of nontraditional assays in an integrated environmental assessment of contaminated ground water
Authors: Twerdok Lorraine E , Burton Dennis T , Gardner Henry S , Shedd Tommy R , Wolfe Marilyn J
Published: March 2010

The toxic potential of ground water contaminated with several probable carcinogenic heavy metals and halogenated solvents was evaluated using an integrated environmental assessment approach. A number of assays, which included acute toxicity, short-term chronic toxicity, genotoxicity, developmental toxicity and carcinogenicity, were used to assist in a hazard assessment. Comprehensive analytical chemistry was performed throughout the 9-month exposure to document the chemical characteristics of the ground water. An initiation-promotion protocol using a non-neoplastic concentration of diethylnitrosamine as an initiator in a 9-month chronic exposure of Japanese medaka (Oryzias latipes) was used to evaluate potential carcinogenicity of the ground water. The fish were exposed to groundwater concentrations of 1% and 10% ground water by volume. No significant lesions were found in the Japanese medaka exposed to groundwater concentrations at 1% or 10% ground water by volume. Likewise, no genotoxicity, developmental toxicity, acute toxicity or short-term chronic toxicity, were found at concentrations of ≤10% ground water by volume. The negative results obtained in this study show that the potential hazard posed by low concentrations of a complex mixture containing suspect carcinogens may not be manifested at environmentally relevant concentrations.
Major ion toxicity of six produced waters to three freshwater species: Application of ion toxicity models and tie procedures
Authors: Tietge Joseph E , Hockett J Russell , Evans James M
Published: March 2010

Previous research to characterize the acute toxicity of major ions to freshwater organisms resulted in the development of statistical toxicity models for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). These ion toxicity models estimate the toxicity of seven major ions utilizing logistic regression. In this study, the ion toxicity models were used in conjunction with Phase I toxicity identification evaluation (TIE) procedures to evaluate the contribution of major ion toxicity to the total toxicity of six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced waters were found to have toxicity consistent with toxicity attributable to major ion concentrations only. Two produced waters were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase I TIE procedures. Toxicities were reduced by specific Phase I TIE manipulations to those predicted by the ion toxicity models. Mock effluents were used to verify the results. The combination of the ion toxicity models with Phase I TIE procedures successfully quantified the toxicity due to major ions in six produced water sample.
Error propagation in fugacity level-III models in the case of uncertain physicochemical compound properties
Authors: Kühne Ralph , Breitkopf Cornelia , Schüürmann Gerrit
Published: March 2010

For a level-III fugacity model to predict the steady-state environmental distribution of chemicals on a regional scale, the effect of erroneous physicochemical input data on the model output was studied using Monte Carlo simulations. Uncertainty analyses were performed for the octanol/water partition coefficient and Henry's law constant with assumed standard errors of 0.5 and 0.1 log units according to corresponding Gauss distributions, using phenol, pentachlorophenol, ethanol, acetone, and anthracene as model compounds. The results showed considerable variations of factors up to 2.5 for the predicted relative distributions among the major compartments. The output variations were greater for compounds with more than one sink. The results demonstrate the need for addressing error propagation in multimedia models in a systematic way.
Variation in DNA content of blood cells of largemouth bass from contaminated and uncontaminated waters
Authors: Lingenfelser Susan F , Dallas Cham E , Jagoe Charles H , Smith Michael H , Brisbin I Lehr , Chesser Ronald K
Published: March 2010

Largemouth bass (Micropterus salmoides) were collected from locations with and without documented histories of pollution in Georgia and South Carolina. Whole blood samples were collected from over 3,000 bass and analyzed by flow cytometry to measure changes in cellular DNA content and cell cycle distribution. The coefficient of variation (CV) of the cell cycle phase G0/G1 peak was used as a measure of variation in DNA content within an individual. The mean CV varied significantly among locations, and some locations with known chemical or radioactive contaminants had higher CVs. Plotting the frequency distribution of CV values for each site revealed greater skewness and kurtosis in most locations with known contaminants. In each case, a right skewness indicated higher proportions of bass with unusually high CV in these locations. Aneuploid-like patterns were detected in the DNA histograms of five fish, all from locations with histories of contamination. The percentage of cells distributed among phases of the cell cycle (G0/G1, S, and G2/M) varied significantly among locations, but there was no apparent relationship to contaminant distribution. Differences in CV and frequency of aneuploids among sites with and without histories of pollution were generally small, but increased variation in DNA content may be associated with contaminant exposure at some locations.
Source and identity of compounds in a thermomechanical pulp mill effluent inducing hepatic mixed-function oxygenase activity in fish
Authors: Martel Pierre H , Kovacs Tibor G , O'Connor Brian I , Voss Ron H
Published: March 2010

The source and identity of two mixed-function oxygenase (MFO)-inducing substances present in the primary-treated effluent of a thermomechanical pulp (TMP) mill producing newsprint was determined. The source was pinpointed by exposing rainbow trout (Oncorhynchus mykiss) to various process effluents sampled throughout the mill. Exposure concentrations were based on the flow of these process streams in relation to the final effluent flow. Contaminated TMP steam condensates were identified as the major process source of MFO-inducing substances. Using conventional extraction and fractionation procedures, an MFO-inducing fraction was isolated. The major gas chromatographic peaks in this fraction were identified by gas chromatography/mass spectrometry as juvabione, dehydrojuvabione, and manool, all naturally occurring extractives in balsam fix (Abies balsamea). These substances were extracted and isolated from balsam fir and TMP condensates. Trout exposed to juvabione and dehydrojuvabione responded by exhibiting significant hepatic MFO inductions. No MFO induction was observed for manool. Secondary treatment in an activated sludge system effectively eliminated the MFO-inducing potential of the combined mill effluent consistent with a corresponding 90% reduction of both juvabione and dehydrojuvabione.
Effects of chlorpyrifos on individuals and populations ofDaphnia pulexin the laboratory and field
Authors: van der Hoeven Nelly , Gerritsen Anton A M
Published: March 2010

Effects of the insecticide chlorpyrifos (cpf) on young (<1 d old) and adult (7–9 d old) Daphnia pulex and the ability of D. pulex to recover after exposure were tested in the laboratory. Populations of D. pulex exposed to cpf were studied in the laboratory and field. In the field, cpf was applied in a single dose. The effects of that dose on D. pulex populations were tested and compared with the effects of a simulated single dose and its ensuing decay on populations in the laboratory. The lowest no-observed-effect concentration was about 0.05 μg/L (actual concentration). Chlorpyrifos immobilized D. pulex several days before death. Juveniles became immobilized faster than adults. Even when no longer exposed, D. pulex immobilized by cpf died. In the laboratory and field, observed population dynamics and effects of cpf on these dynamics were very similar. The median effective concentration for population size after 2 and 7 d of exposure did not differ between the laboratory and field (2 d, 0.38 and 0.31 μg/L, respectively; 7 d, 0.25 and 0.34 μg/L, respectively). Effects of cpf on single-species Daphnia populations in the laboratory and field can be predicted from effects observed in tests with individuals.
Equilibrium partitioning of heavy metals in dutch field soils. II. Prediction of metal accumulation in earthworms
Authors: Janssen René P T , Posthuma Leo , Baerselman Rob , Den Hollander Henri A , Van Veen Rens P M , Peijnenburg Willie J G M
Published: March 2010

To evaluate the adequacy of the equilibrium partitioning concept in predicting metal bioaccumulation, a soil invertebrate species was exposed in 20 Dutch field soils with moderate metal contamination. Earthworms (Eisenia andrei) were kept in the soils for 3 weeks under laboratory conditions. Bioconcentration factors (BCFs) for six metals (Zn, Cu, Pb, Cd, Cr, Ni) and for As were calculated as the ratio of body- and solid-phase metal concentrations. Multivariate statistical analyses suggested that the BCFs for As, Cd, Cu, and Zn are governed by the same soil characteristics that determine equilibrium partition coefficients between the soil solid phase and the pore water. This suggests that uptake of metals is either direct from the pore water or indirect through an uptake route closely related to pore water. Regression equations were derived for predicting BCF values as a function of easily determinable soil characteristics. By means of internal validation it was shown that the equations obtained can be used for predictive purposes within the range of soil properties encountered in the dataset. Due to a lack of data, external validation was possible only in a qualitative sense.
Accelerated increase in mercury contamination in north Atlantic mesopelagic food chains as indicated by time series of seabird feathers
Authors: Monteiro Luís R , Furness Robert W
Published: March 2010

Concentrations of mercury in the environment have increased manyfold since preindustrial times as a result of anthropogenic emissions of gaseous mercury to the atmosphere. However, most records of historical change are affected by regional inputs and evidence of global impact of human activities at pristine oceanic sites is scanty. Seabird feathers contain a valuable record showing historical trends in methylmercury contamination. Some seabirds are top predators in epipelagic and others in mesopelagic food chains and thus reflect methylmercury contamination of these ecosystems. Here, we report the first measurements of mercury concentrations in a time series of animals from the subtropical northeast Atlantic over the last 100 years. These data show increases in mercury levels by 1.1 to 1.9%/year in epipelagic foodchains and by 3.5 to 4.8%/year in mesopelagic food chains. While the rate of increase in the epipelagic ecosystem is in close agreement with model predictions, the higher rate in the mesopelagic ecosystem has not previously been detected. However, the latter concurs with methylmercury production below the thermocline and conveys new insights into the understanding of the anthropogenic impact in the marine cycle of mercury.
Dietary uptake in pike (Esox lucius) of some polychlorinated biphenyls, polychlorinated naphthalenes and polybrominated diphenyl ethers administered in natural diet
Authors: Burreau Sven , Axelman Johan , Broman Dag , Jakobsson Eva
Published: March 2010

The dietary uptake of 12 halogenated diaromatic compounds was studied using northern pike (Esox lucius L.) fed with rainbow trout (Oncorhynchus mykiss (Walbaum)). Before the trout were fed to the pike, they had been injected with a cocktail of five polychlorinated biphenyls, four polychlorinated naphthalenes, and three polybrominated diphenyl ethers, dissolved in rainbow trout lipid. The reported uptake efficiencies (E) were in the range 35 to 90% and differ in some respect from earlier studies. The E-values for those substances with effective cross sections (ECS) >9.5 Å were considerably higher than expected if the membrane permeation at dietary uptake was restricted as proposed previously in the literature. There was no hydrophobicity dependency of the total dietary uptake efficiency as suggested by an earlier proposed empirical model. The difference between the results presented here and earlier studies is likely to depend on cotransport with lipids and/or proteins through a mediated, possibly active uptake of hydrophobic organic compounds (HOC) in the gastrointestinal tract enabled by the actual exposure method. For the proposed mediated/active uptake of HOCs, the uptake efficiency varied with molecular weight and was greatest for a molecular weight of approximately 450.
Xenobiotic and steroid biotransformation enzymes in Atlantic salmon (Salmo salar) liver treated with an estrogenic compound, 4-nonylphenol
Authors: Arukwe Augustine , Förlin Lars , Goksøyr Anders
Published: March 2010

Hepatic microsomal biotransformation reactions with xenobiotic and steroid substrates have been investigated in 4-non-ylphenol (NP; 1, 5, 25, and 125 mg/kg body weight)-treated juvenile Atlantic salmon (Salmo salar), in addition to control and estradiol-17β (5 mg/kg, positive control)-treated fish. Treatment of juvenile salmon with NP caused an initial increase and an apparent dose-dependent decrease in progesterone 6β-, 16α, and 17α-hydroxylase activities in liver microsomes. 7-Ethoxyresorufin O-deethylase and UDP-glucuronosyltransferase activities were also reduced. Plasma levels of estradiol-17β (E2) were lowered 24–43% as a result of NP treatment. Immunochemical analysis of CYP1A, CYP2K-like, and CYP3A-like proteins showed 18%, 47%, and 30% reductions in enzyme-linked immunosorbent assay absorbance levels, respectively, in the groups treated with 125 mg NP/kg fish. The group treated with E2 also showed similar reductions. In summary, the present study has demonstrated variations in steroid hydroxylases, cytochrome P450 isozymes, and conjugating enzyme levels in NP-treated juvenile salmon. These results represent a novel aspect of NP effects not previously demonstrated with an environmental estrogen in any fish species or lower vertebrate.