bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity of inorganic and organic selenium to Daphnia magna (cladocera) and Chironomus riparius (diptera)
Authors: Ingersoll C. G. , Dwyer F. J. , May T. W.
Published: March 2010

Elevated concentrations of selenium (Se) have been previously measured in biota sampled from the Kesterson National Wildlife Refuge (KNWR) in the San Joaquin Valley of central California. We conducted acute and chronic toxicity tests with the cladoceran Daphnia magna and the midge Chironomus riparius to determine the toxicity or bioaccumulation of waterborne Se in a reconstituted water similar to the San Joaquin River. Daphnids were more acutely sensitive than midges to the toxic effects of inorganic Se. An organic form of Se (seleno-[L]-methionine) was extremely toxic to daphnids, but was relatively nontoxic to midges. In long-term exposure to a 6:1 mixture of selenate to selenite (a mixture representative of KNWR), the emergence time of adult midges was delayed at Se concentrations ≥ 837 μg/L. Daphnid reproduction and intrinsic rate of natural increase (r) were reduced at Se concentrations ≥ 348 μg/L and growth of adults was reduced at ≥ 156 μg/L. Whole body Mg, K and Na concentrations in daphnids were not affected by chronic Se exposure; however, whole body Ca concentration increased at intermediate Se exposure concentrations. In addition, whole body Cl concentration was reduced at 711 μg Se/L. Daphnids accumulated potentially toxic concentrations of Se from water that may adversely affect fish or waterfowl through the food chain.
Simplification of in vitro culture techniques for freshwater mussels
Authors: Keller Anne E. , Zam Stephen G.
Published: March 2010

Populations of freshwater mussels have been declining for several decades due to habitat destruction, pollution and sedimentation. Efforts to propagate rare and endangered species in the laboratory have been hampered by their need for fish as hosts during a brief parasitic phase in early development and more recently, by cumbersome alternative methods. The methods developed here are simple and use common tissue culture products that standardize the procedures allowing production of large numbers of juvenile mussels for replenishment of wild mussel populations or for use in toxicity testing protocols. Anodonta imbecilis, Lampsilis teres and Villosa lienosa have been successfully propagated using these methods.
Effects of selected PCB congeners on survival, growth, and reproduction inDaphnia magna
Authors: Dillon Tom M. , Benson William H. , Stackhouse R. Allan , Crider A. Michael
Published: March 2010

The effects of individual polychlorinated biphenyl (PCB) congeners on survival, growth and reproduction in the freshwater cladoceran, Daphnia magna, were determined. Congeners evaluated in this study (IUPAC numbers 52, 77, 101, 118, 138, 153, 180) represent a variety of microsomal mixed-function oxidase (MFO) inducers. After 21 d of static renewal exposure, Daphnia survival was high (88–100%) in all congener treatments and unaffected by any PCB. Polychlorinated biphenyl congeners had little to no detectable sublethal effects on reproduction and growth. The number of neonates produced was either unaffected (congeners 52, 77, 118) or enhanced (congeners 101, 138, 153, 180). Effects on total biomass were mixed and the magnitude of significant differences, when observed, was small. Diminished biomass was observed in Daphnia exposed to congener 101 whereas increases occurred in treatments with congeners 52 and 118. Both elevated and diminished biomass was observed in animals exposed to congener 77. Congeners 138, 153 and 180 had no significant effect on Daphnia biomass.

Daphnia accumulated substantial amounts of all PCBs even though minimal effects on survival, growth and reproduction were observed. Mean tissue concentrations ranged from approximately 2.0 ng/mg to 130 ng/mg dry weight. These tissue residues are one to several orders of magnitude greater than those observed in aquatic fish and invertebrates collected in and around industrial waterways of the Great Lakes. Possible explanations for the lack of PCB congener toxicity are discussed.
The octanol/water partition coefficient of methylmercuric chloride and methylmercuric hydroxide in pure water and salt solutions
Authors: Major Michael A. , Rosenblatt David H. , Bostian Karen A.
Published: March 2010

The 1-octanol/water partition coefficient (Kow) of methylmercury was determined at pH 7 in water and in aqueous solutions ranging from 0.0003 to 0.6000 M in sodium chloride. It was also determined over a pH range of 2 to 10 with a fixed sodium chloride concentration of 0.0045 M. In these experiments, Kow was seen to increase with increasing chloride concentrations in the range 0.0 to 0.075 M and to decrease with increasing pH above 7. Results were similar whether low levels of methylmercuric chloride or methylmercuric hydroxide were used as the starting materials. Partitioning was not affected by changes in ionic strength.
Routes of uptake and their relative contribution to the toxicologic response of Northern bobwhite (Colinus virginianus) to an organophosphate pesticide
Authors: Driver Crystal J. , Drown David B. , Ligotke Michael W. , Van Voris Peter , McVeety Bruce D. , Greenspan Bernard J.
Published: March 2010

Ingestion of contaminated food is considered the primary route of exposure in birds to agricultural chemicals. Routes of exposure other than ingestion are not often considered in risk assessments of agricultural chemicals to avian wildlife. However, recent studies demonstrated anorexic or avoidance behaviors in birds exposed to organophosphate (OP) insecticides. These behaviors would tend to limit exposure if ingestion alone were considered. The contribution, if any, of dermal, preening, and respiratory pathways to the exposure of birds to pesticides under field conditions is unknown. In addition, oral exposures are currently assessed in artificial environments that do not reflect real-life exposure scenarios. To determine the relative contribution of these pathways and to assess exposures under ecological conditions, 270 northern bobwhite (Colinus virginianus) were exposed to simulated aerial crop applications of methyl parathion in an environmentally controlled wind tunnel. The wind tunnel environment consisted of a 25-cm cotton plant canopy, a 5-cm-thick floor of silt-loam, a temperature of 25°C, 50% RH, UV intensity similar to summer sunlight, and a wind speed of 3.2 km/h. Inhalation, preening, and dermal routes were isolated in groups of birds exposed to each application. Five birds from each group were collected at 1, 4, 8, 24, and 48 h post-spray to determine cholinesterase (ChE) response to the exposures. Contaminated and uncontaminated darkling beetle (Tenebrio molitar) larvae were presented to free-ranging sprayed birds in the wind tunnel to assess oral uptake. ChE response was determined at 4, 8, 24, and 48 h postspray. All exposures were replicated. All four routes contributed to the inhibition of brain ChE at different post-spray periods. Dermal uptake and preening were major contributors to the overall dose and toxic response of birds to methyl parathion. Inhalation was the major route of exposure at 1 h post-spray. At 4 h post-spray, uptake through preening caused the greatest inhibition of brain ChE activity. Oral ingestion resulted in less than 20% inhibition of brain ChE during the test. Routes of uptake in order of contribution to toxicologic response from 8 to 48 h post-spray were dermal > preening ≥ oral > inhalation.
Toxicokinetics and toxicity of a mixture of sediment-associated polycyclic aromatic hydrocarbons to the amphipod Diporeia sp
Authors: Landrum Peter F. , Eadie Brian J. , Faust Warren R.
Published: March 2010

Amphipods, Diporeia sp., were exposed to a reference sediment dosed with two radiolabeled polycyclic aromatic hydrocarbons (PAHs) and sediments dosed with a mixture of PAHs at four concentrations: 21.4, 41.0, 119.6, and 327.0 nmol g−1 dry sediment, as the molar sum of the PAH congeners. Diporeia sp. were sampled for mortality and toxicokinetics for up to 26 d. Significant sediment avoidance was observed at the highest dose out to 6 d of exposure. The toxicity for the mixture was 38 ± 3% after 19 d of exposure at the highest dose, 327 nmol g−1 dry sediment as the molar sum of the PAHs. The measured organism concentration required to produce the mortality at day 19 was 2.9 μmol g−1 as the sum of the bioaccumulated PAHs. The uptake clearance (g dry sediment g−1 organism h−1) from sediments for the radiotracers increased with dose to an apparent plateau. Uptake clearance is the conditional constant relating the contaminant flux into the organism to the contaminant concentration in the referenced environmental compartment, in this case the sediment. This enhanced bioavailability with dose occurred even in the absence of overt effects and in the absence of changes in the measured partition coefficients for phenanthrene (273 ± 98) and pyrene (540 ± 212), between the freely dissolved radiotracers in interstitial water and the sediment particles. These changes in bioavailability with changes in PAH concentration suggest that predictions of bioaccumulation of PAH congeners from sediments under different field concentration conditions will not be possible with standard partitioning relationships.
Mitochondrial response to chlorophenols as a short-term toxicity assay
Authors: Shannon Robert D. , Boardman Gregory D. , Dietrich Andrea M. , Bevan David R.
Published: March 2010

In this investigation the effects of chlorophenols on rat liver mitochondrial respiratory parameters were determined and compared to the toxicities of those compounds in a variety of biological systems currently being used for toxicity testing. Mitochondrial fractions were exposed to six concentrations of five different chlorophenols in a semiclosed, 2-ml reaction vessel. Respiratory parameters were measured polarographically with an oxygen electrode and compared to control experiments. The toxicity of the chlorophenols, as measured by the concentration reducing the respiratory control ratio of the control to 50% (RCR50), increased with increasing chloro substitution. RCR50 concentrations ranged from 599 μM with 2-chlorophenol to 0.110 μM with pentachlorophenol.

The RCR50 concentrations for the five chlorophenols were compared to six physicochemical parameters for the same chlorophenols; high degrees of correlation between the RCR50 concentrations and the physicochemical parameters were found (r ≥ 0.890). The highest correlation coefficient obtained was with the n-octanol/water partition coefficient (r = 0.991), indicating that the ability of chlorophenols to partition into the lipid mitochondrial membrane plays a significant role in eliciting its toxic effect. RCR50 concentrations were also compared to nine currently existing short-term toxicity tests. High degrees of correlation were obtained with several of the tests, including algal, bacterial, and fish bioassays. This suggests that the uncoupling of oxidative phosphorylation may be the major mechanism by which chlorophenols cause toxicity to intact cells as well as more complex organisms.

The use of mitochondrial respiratory parameters appears to offer a complementary approach as a short-term toxicity test for this class of compounds. Further development and testing with a variety of other toxicants is suggested.
A four-day survival and reproduction toxicity test for ceriodaphnia dubia
Authors: Oris James T. , Winner Robert W. , Moore Marianne V.
Published: March 2010

A 4-d survival and reproduction toxicity test utilizing Ceriodaphnia dubia has been developed and evaluated. This toxicity test has been compared to the standard 7-d test using a total of 12 toxicants encompassing a wide range of chemical classes. In addition, 48-h LC50 values were determined for each chemical in the absence of food. Four-day and seven-day tests were run concurrently, twice for each chemical. Less-than-12-h-old neonates for both 4-d and 7-d tests were segregated into individual test cups on Fridays. Animals for 7-d tests were immediately exposed to the test chemical. Animals for 4-d tests were held in control water and not exposed to the test chemical until day 3. Animals were fed daily and solutions were changed on Mondays and Wednesdays. Chemical concentrations were measured by appropriate analytical techniques during each test. Survival and mean total young per female were used to compare the relative sensitivity of the 4-d and 7-d tests. Data were analyzed using traditional hypothesis testing techniques to determine chronic values from the no-observed- and lowest-observed-effect concentrations. In addition, data were analyzed using a nonparametric, monotonic smoothing technique to determine interpolated point estimates and 95% confidence intervals for the 50% inhibition concentration (IC50). Comparisons between the 4-d test versus the 7-d test for both methods of data analysis indicated that the 4-d test provides an acceptable level of sensitivity in the toxicity testing of single compounds.
Brain cholinesterase activity of bobwhite acutely exposed to chlorpyrifos
Authors: Cairns Michael A. , Maguire Christine C. , Williams Bill A. , Bennett Jewel K.
Published: March 2010

Northern bobwhite, Colinus virginianus, were orally dosed with the organophosphorus insecticide chlorpyrifos to examine effects on brain chohnesterase (ChE) activity. Two-week-old quail were acutely exposed and euthanized at selected times following gavage-dosing, ranging from I to 120 h later. The ChE activity was determined in treated birds and compared to concurrently tested control (corn oil) birds. It was found that a lag time of 2 to 4 h following exposure was necessary to detect significant ChE depression caused by chlorpyrifos. The lowest dose that produced ChE depression in these tests was between —30 and 50 mg chlorpyrifos/kg body weight, with some mortality occurring at the high end of that range. Depression typically persisted for at least 24 h.
Long-term persistence of polychlorinated biphenyl congeners in blood and liver and elevation of liver aminopyrine demethylase activity after a single high dose of aroclor 1254 to mice
Authors: Anderson Lucy M. , Dixon Dwayne , Beebe Lisa E. , Fox Steven D. , Issaq Haleem J.
Published: March 2010

Poorly metabolized polychlorinated biphenyl (PCB) congeners are bioaccumulated in the bodies of rodents and humans. Little is known about the continuing biological effects of these persistent chemicals. To determine whether a single high dose of a PCB mixture to mice would have long-term effects on liver enzymes, Aroclor 1254 was given at a single dose of 500 mg/kg to (C57BL/6 × DBA/2)F1 female mice. Paired controls received olive oil. Mice were killed at intervals of 0.5 to 55 weeks after treatment and liver assessed for aminopyrine demethylase activity. At selected time points, blood and homogenates of liver and of whole carcass were analyzed for content of PCBs by gas chromatography with electron capture detection. Hepatic aminopyrine demethylase activity was significantly elevated in Aroclor-treated mice, relative to controls, for 42 weeks after treatment. A three- to fourfold increase persisted for at least 14 weeks, with a convergence of treated and control values thereafter. Significant amounts of nine PCB congeners were detected in carcass, liver, and blood; total carcass PCB, estimated on the basis of these congeners, correlated significantly with liver aminopyrine demethylase elevation, and a similar trend was noted for liver. At 42 weeks after treatment, total PCB levels were 70 mg/kg for carcass, 2.4 mg/kg for liver and 0.28 mg/kg for blood. Congener profiles were similar in all three compartments, with the majority of the retained chemical being 2,3′,4,4′,5- and 2,3,3′,4,4′-pentachlorobiphenyl and 2,2′,4,4′,5,5′-and 2,2′,3,4,4′,5′-hexachlorobiphenyl. These results suggest that congeners bioaccumulated after a high PCB dose retain biological activity in the body for nearly a year after treatment.
Biological and biochemical effects of retained polyhalogenated hydrocarbons
Authors: Beebe Lisa E. , Anderson Lucy M. , Fox Stephen D. , Issaq Haleem J.
Published: March 2010

The polyhalogenated aromatic hydrocarbons (PHHs), consisting of the chlorinated and brominated biphenyls, dibenzo-p-dioxins and dibenzofurans, are important environmental contaminants affecting both wildlife and humans. Although the biological effects due to acute or chronic exposure to these compounds have been extensively investigated with animal models, relatively little is known concerning the long-term ramifications of such exposure due to the persistent body burdens of some PHH congeners. This review examines the persistent effects of these contaminants for two biological end points: tumor formation and induction of cytochrome P-450-associated mixed function oxygenases in target tissues. Literature and data are presented that indicate that retained PHH congeners continue for many months to exert biological effects that contribute to tumor development in rodent livers and lungs. Effects of specific congeners, retention profiles of these congeners in target tissues and the long-term induction of cytochrome P-450 IA1-associated enzyme activity are all consistent with activation of the Ah receptor's being an integral part of the tumor promotion response.
Effects of a contaminated sediment on life history traits and population growth rate of Neanthes arenaceodentata (polychaeta: Nereidae) in the laboratory
Authors: Pesch Carol E. , Munns Wayne R. , Gutjahr-Gobell Ruth
Published: March 2010

The effects of a highly contaminated sediment on life history traits and population dynamics of the nereid polychaete. Neanthes arenaceodentata Moore were assessed in a laboratory experiment Survival, growth and fecundity were measured for one generation of worms exposed to 40 and 10% Black Rock Harbor, Connecticut (BRH) sediment (a contaminated sediment), 100% reference (REF) sediment from central Long Island Sound (the control) and a no-sediment treatment (to follow progress of pairing and reproduction) The BRH sediment did not affect survival or size of adults or number of broods Number of eggs per brood appeared to be lower in 40% BRH sediment than 10% BRH or REF sediment, but the difference was not significant (1,397, 1,621 and 1,556 eggs per brood, respectively) However, number of larvae per brood was significantly lower in the 40% BRH sediment than in 10% BRH or REF sediment (363, 770 and 850 larvae per brood, respectively) Number of juveniles appeared to be lower in 40% BRH than in the other sediment treatments, although the differences were not significant Size of juveniles did not differ in the sediment treatments The finite multiplication rate of population increase, λ, was the same for all treatments The lack of significant differences but the presence of some trends may indicate that 40% BRH sediment was not a high enough dose to produce significant effects Effects of BRH sediment on other species are discussed. In conjunction with an earlier study, this work demonstrates that population responses of life cycle tests with Neanthes arenaceodentata can be used to evaluate the chronic toxicity of sediments, which could provide comparative toxicological data to evaluate the relative sensitivity of this and other marine species and may serve as a model system to study questions in population biology
Uncertainty in ocean-dumping health risks: Influence of bioconcentration, commercial fish landings and seafood consumption
Authors: Lipton Joshua , Gillett James W.
Published: March 2010

Human consumption of marine organisms that have been contaminated by ocean disposal of municipal sewage sludges may pose significant health risks. Previous models of ocean dumping health risk, however, have failed to assess uncertainties associated with model parameters. This failure has resulted in risk assessments that may be misleading to policymakers. Uncertainties regarding contaminant bioaccumulation, commercial fish landings and seafood consumption were incorporated into a model of carcinogenic health risk for two materials found in municipal sewage sludges, dichlorodiphenyltrichloroethane and metabolites (DDT-R) and polychlorinated biphenyls (PCBs). Iterative Latin hypercube simulation was employed to generate probability distributions of health risks. Results indicate that parameter variability and uncertainty, particularly in bioaccumulation models, can lead to a several-orders-of-magnitude range in estimated risk values. This distributional range straddles current risk-management thresholds, suggesting that ocean disposal of municipal sludges may, indeed, pose substantial health risks to seafood consumers under certain sets of conditions and assumptions. Moreover, if not explicitly considered in risk models, uncertainty can lead to errors in risk-based decision making.
The relationship of parathion concentration, exposure time, cholinesterase inhibition and symptoms of toxicity in midge larvae (chironomidae: Diptera)
Authors: Detra Randall L. , Collins William J.
Published: March 2010

Larvae of Chironomus riparius were used to demonstrate a statistically significant relationship between four variables: parathion concentration in water (nominally 20 to 500 μg/L), duration of exposure, symptoms of toxicity, and in vivo cholinesterase (ChE) inhibition. The symptoms of toxicity were a series of swimming behaviors that were categorized and assigned numerical values according to intensity of poisoning. These values were correlated with ChE inhibition by a polynomial regression. Therefore, symptoms of poisoning could be mathematically estimated from measurements of percent ChE inhibition. A three-dimensional relationship between ChE inhibition, the logarithm of exposure time, and the logarithm of parathion concentration was established. This permits the characterization of the range of conditions for the onset of a given toxicity symptom and also predicts the symptom for which values for at least two of these variables are provided.
Optimizing btex biodegradation under denitrifying conditions
Authors: Hutchins Stephen R.
Published: March 2010

Laboratory tests were conducted to determine optimum conditions for benzene, toluene, ethylbenzene, and xylene (collectively known as BTEX) biodegradation by aquifer microorganisms under denitrifying conditions. Microcosms, constructed with aquifer samples from Traverse City, Michigan, were amended with selected concentrations of nutrients and one or more hydrocarbons. Toluene, ethylbenzene, m-xylene, and p-xylene were degraded to below 5 μg/L when present as sole source substrates; stoichiometric calculations indicated that nitrate removal was sufficient to account for 70 to 80% of the compounds being mineralized. o-Xylene was recalcitrant when present as a sole source substrate, but was slowly degraded in the presence of the other hydrocarbons. Benzene was not degraded within one year, regardless of whether it was available as a sole source substrate or in combination with toluene, phenol, or catechol. Pre-exposure to low levels of BTEX and nutrients had variable effects, as did the addition of different concentrations of ammonia and phosphate. Nitrate concentrations as high as 500 mg/L NO3-N were slightly inhibitory. These data indicate that nitrate-mediated biodegradation of BTEX at Traverse City can occur under a variety of environmental conditions with rates relatively independent of nutrient concentrations. However, the data reaffirm that benzene is recalcitrant under strictly anaerobic conditions in these samples.
Effects of largemouth bass stocking rate on fish populations in aquatic mesocosms used for pesticide research
Authors: Deutsch William G. , Webber E. Cliff , Bayne David R. , Reed Clarence W.
Published: March 2010

From 1988 to 1989, the effects of largemouth bass (Micropterus salmoides Lacepede) stocking rate on bluegill (Lepomis macrochirus Rafinesque) and bass populations were studied in twelve 0.1-ha mesocosms in Alabama. About 240 mature bluegill were stocked in each pond in May, and their reproduction was monitored biweekly from June through September. Bass fingerlings were stocked at rates of 15, 28, and 55 fish per pond (four replicates) in June, and all fish were harvested in February. Mean length, weight, and relative condition of bass and number of young bluegill decreased with increasing stocking rate. Mean weight, growth, and relative condition of adult blue-gill were directly related to stocking rate. A bimodal spawning pattern of bluegill was observed in all treatments, but the second peak was three-fold greater in the high bass rate than in the low. A combination of bass and bluegill in mesocosms offers several advantages over bluegill alone. The medium bass stocking rate is recommended to maintain both fishes in good condition. Alternatively, bass may be crowded to keep bluegill in peak reproductive condition and optimal growth, prevent overcrowding of young bluegill, and reduce predation pressure on invertebrate populations.
The mixing, distribution and persistence of esfenvalerate within littoral enclosures
Authors: Heinis Larry J. , Knuth Michael L.
Published: March 2010

The synthetic pyrethroid insecticide esfenvalerate was applied to the surface of 18 littoral enclosures (5 × 10 m) in a 2-ha pond near Duluth, Minnesota. The insecticide was applied as Asana® 1.9 emulsifiable concentrate (EC) at five nominal concentrations ranging from 0.01 to 5.0 μg/L active ingredient. Two applications were made 30 d apart. Samples of water, sediment, macrophytes, enclosure wall material, and fish were collected and analyzed for esfenvalerate residue. Maximum water concentrations occurred 1 to 3 h after application and rapidly decreased during the next 24 h. At 5.0 μg/L, 90% of the active ingredient was lost from the water column within 24 h and was below the detection limit (0.047 μg/L) within 4 d. A vertical concentration gradient was observed following application, with 95% of the measured esfenvalerate contained in the upper 75% of the enclosure water column 24 h after application. All other components of the pond ecosystem contained measurable amounts of esfenvalerate. Water and sediment, and, to a lesser extent, aquatic vegetation and macrophytes, were important reservoirs for esfenvalerate. Cumulative sorption of esfenvalerate to sediment and enclosure wall material was observed after two successive applications to littoral enclosures.
Ecosystem-level testing of a synthetic pyrethroid insecticide in aquatic mesocosms
Authors: Webber E. Cliff , Deutsch William G. , Bayne David R. , Seesock Wendy C.
Published: March 2010

Twelve 0.1-ha rectangular ponds (mesocosms) were constructed during 1986 and 1987 to test ecosystem-level responses to a pyrethroid insecticide containing esfenvalerate. Treatment consisted of 10 weekly drift and 5 biweekly runoff simulations of formulated esfenvalerate between July 9 and September 17, 1988. Control ponds received only untreated runoff, while low, medium, and high treatments received total loadings of 0.23, 4.1, and 23.3 g active ingredient (a.i.)/ pond. The top vertebrate predator in the mesocosms was bluegill (Lepomis macrochirus). Once adult blue-gill spawned and young fish were present, microcrustaceans declined in number. Following esfenvalerate applications, nauplii in medium- and high-rate ponds underwent further significant reductions, indicating a response to esfenvalerate not observed in control and low-rate ponds. Relative to other treatments, high-rate ponds were found to have significantly increased metabolism and reduced macroinvertebrates following application. Bluegill exhibited no significant differences in population structure among treatments, although 2-cm-size bluegill were missing from high-rate ponds at harvest. Patterns of response emerged in this whole ecosystem test of esfenvalerate. Variation measured among communities was high as is typical of natural ecosystems; however, we suggest that this experiment provided an acceptable way of detecting impacts at both the community and the ecosystem level.
Orientation of sampling grids for determining the extent of wavefront contamination
Authors: Skalski J. R.
Published: March 2010

Traditionally, sampling grids for the detection of hazardous waste plumes are oriented perpendicularly to the direction of the wavefront of the contaminant. When rotated 45° to the direction of the wavefront, square lattices reduce the maximum waste plume that could go undetected and reduce the number of sampling stations. Improved site characterization and reduced sampling costs can both be achieved through this simple modification.
The distribution of relative error of toxicity of herbicides and metals to Arabidopsis
Authors: Shirazi M. A. , Ratsch H. C. , Peniston B. E.
Published: March 2010

Median toxicity end points such as EC50 and LC50 numbers are commonly reported in the literature for summarizing results of a whole test. A median number is frequently accompanied with a statement of error often derived from theoretical and idealized models. Toxicity end points other than EC50 are seldom reported, and the distribution of their error based on real data remains unexplored. More general toxicity estimates—for example, ECX, where X is any percent response—frequently are needed in environmental risk assessment. An analysis of distribution of the standard error (SE) of toxicity ECX for an array of chemicals tested with Arabidopsis shows that ECX errors cannot be extrapolated from EC50 errors. The analysis includes detailed chemical-by-chemical toxicity end points covering the full range of tested concentrations. A generalized relative error distribution is produced from the data, and its utility for research and environmental management is discussed.
Effects of chlorpyrifos on a microecosystem
Authors: Kersting Kees , van Wijngaarden René
Published: March 2010

A recirculating aquatic microecosystem consisting of three subsystems and with a total volume of 7.5 L was used to study effects of the insecticide chlorpyrifos. The three subsystems represent the trophic levels of primary producers (algae), herbivores (Daphnia magna), and decomposers (bacteria on a sand filter). Two of four microecosystems were perturbed with chlorpyrifos 429 d after they were started. All subsystems were monitored weekly for several chemical and biological variables. The response of the systems was followed for 130 d after chlorpyrifos application. An immediate decrease of the Daphnia population could be explained from the mortality observed in single species tests. The population recovered within two weeks. Two weeks after the introduction of chlorpyrifos, the pH in all subsystems dropped by about two units. Concurrent with the pH changes, there were changes in the algal biomass, the Daphnia numbers, and the oxygen concentrations. The pH in the treated systems was comparable to the controls about 90 d after the treatment, but the other variables did not recover. These effects were not predicted by any single-species test and, therefore, represented ecosystem effects.
Radon remediation studies in northern Virginia and southern Maryland
Authors: Mose Douglas G. , Mushrush George W.
Published: March 2010

A three year study of indoor radon in more than 1,000 homes in northern Virginia and southern Maryland was conducted by using three month-exposure alpha-track monitors In a study set of approximately 200 homes, first floor indoor radon concentrations, which most closely ap proximate home exposure levels, averaged slightly more than 3 pC1/L In a study set of approximately 100 homes, radon concentrations in the water supplies were < 10,000 pC1/L, and no evidence was found to indicate that the waterborne radon concentration was related to the airborne radon concentration

In a study set of approximately 100 homes, subslab ventilation was used to reduce indoor radon concentrations Interest in remediation was related to public perception of radon hazard, in that people with indoor radon measurements of >4 pC1/L were more likely to participate in the reme diation phase of the project Subslab ventilation was successful in >90% of the homes in reducing indoor radon from concentrations as high as 30 pC1/L to <4 pC1/L, at least for the entire year of postremediation radon measurements
Uncertainty and sediment quality assessments: I. Confidence limits for the triad
Authors: Alden Raymond W.
Published: March 2010

The Sediment Quality Triad is an approach that has been used in the assessment of anthropogenic degradation of three complementary components of sediment quality sediment chemistry, sediment toxicity, and in situ effects on the benthic biota Triad plots represent one way to summarize the relative impact for each of these components through the display of “ratio-to-reference” (RTR) values on three axes Although environmental managers can readily interpret the patterns on Triad plots, the conventional presentation has no provisions for the display of confidence limits on the RTR indexes An investigation was conducted that employed simulation techniques to determine the effect of the RTR process on the interpretation of Triad plots constructed for single samples and a method for placing confidence limits on the Triad axes The simulations were based on empirical data sets from benthic biological surveys taken in two regions in the port of Hampton Roads, Virginia, which represented “reference” and “impacted” groups for the “in situ effects” component of the Triad The process of making ratios produced highly non-normal (skewed to the left) distributions of RTR values that were not amenable to the development of confidence limits by conventional statistical techniques Furthermore, the RTR approach produced high probabilities of “Type II” errors for at least one of the indexes (species richness) when applied to single samples taken from reference and impacted populations shown a priori to be very significantly different from each other “Bootstrap” simulation techniques produced confidence limits based on data that were “unit deviate standardized” (UDS approach) or standardized to the mean of the reference data (“ratio-to reference mean,” or RTRM, approach) The UDS approach provides equal weight to all variables, whereas the RTRM approach allows a variable displaying a great degree of difference between reference and test data sets to have a more dominating influence on the Triad assessment
Zinc toxicity and its interaction with cadmium in the submerged aquatic macrophyte Lemna Trisulca L
Authors: Huebert David B. , Shay Jennifer M.
Published: March 2010

Lemna trisulca L was grown axenically with a regular replacement of a complete filter-sterilized medium containing various amounts of zinc and/or cadmium Levels of Zn greater than 3 0 to 4 5 μM decreased the multiplication rate The EC50 was estimated at 5 0 μM Zn for final yield and at 14 μM Zn for multiplication rate There was a significant Zn by Cd interaction, increased Zn levels mitigated the inhibitory effect of Cd on the multiplication rate and final yield of Lemna trisulca cultures Increasing the external Zn concentration from 0 08 μM to 3 06 μM decreased Cd uptake, but further increases in the external Zn concentration to 6 12 and 12 2 μM Zn promoted plant uptake of Cd from the medium Uptake of Zn by Lemna trisulca ranged from a low of 0 9 to 2 0 μmol Zn per gram dry weight at 0 08 μM Zn, to a high of 120 to 150 μmol Zn per gram dry weight at 12 2 μM Zn
Analysis and prediction of hydrophobicity parameters of substituted acetanilides, benzamides and related aromatic compounds
Authors: Nakagawa Yoshiaki , Izumi Keiichi , Oikawa Nobuhiro , Sotomatsu Tomoko , Shigemura Masao , Fujita Toshio
Published: March 2010

The partition coefficient P in the 1-octanol/water system was analyzed for a great number of multisubstituted benzenes of ecotoxicological importance consisting of acetanilides, benzamides, nitrobenzenes, and anisoles having various substitution patterns in terms of the Δ log P (log P – log P[unsubstituted benzene]) quantitatively with free energy-related physicochemical substituent parameters. The analyses showed that the stereoelectronic effects of ortho, meta, and para substituents on the relative solvation of individual polar groups capable of hydrogen bonding with the partitioning solvents are very important in determining the variations in the log P value. The effects were additive in the set of complicated multisubstituted benzenes, leading to a correlation equation represented by a linear combination of terms of hydrophobic, electronic, and steric parameters summed up over substituents. It was suggested that the procedure be extended to analyze and predict the log P value of any multiply substituted benzenes.
Aquatic environmental chemistry of 2-(thiocyanomethylthio)benzothiazole and related benzothiazoles
Authors: Brownlee Brian G. , Carey John H. , MacInnis Gordia A. , Pellizzari Ian T.
Published: March 2010

BUSAN 30WB® is an alternative to pentachlorophenol as an antisapstain agent in the lumber industry. The active ingredient is 2-(thiocyanomethylthio)benzothiazole (TCMTB). Because very little information is available in the open literature on the fate of TCMTB in aquatic environments, we wish to report our studies on TCMTB and related benzothiazoles, some of which are potential transformation products of TCMTB. We measured the water solubility and octanol/water partition coefficients of TCMTB, benzothiazole (BT), 2-mercaptobenzothiazole (MBT), and 2-(meth-ylthio)benzothiazole (MTBT). The water solubility of TCMTB at 24°C was 40 mg/L, and the log Kow was 3.12. At pH 8 and 24°C in dilute borax-phosphate buffer, the half-life of TCMTB was 750 h; in seawater (pH 7.8-8.0, 24°C) it was about 740 h. Attempts to measure sediment/water partitioning of TCMTB produced traces of MTBT, presumed to result from biological methylation of MBT released by hydrolysis of TCMTB. MTBT was produced directly from MBT in the presence of sediment. In phosphate buffer, TCMTB readily underwent direct photolysis in sunlight to produce MBT, in about 50% yield, and traces of BT. The photochemistry of MBT, the major photolysis product of TCMTB, was studied in some detail. Sunlight quantum yields of TCMTB and MBT are estimated to be 0.01 and 0.002, respectively. Sunlight photolysis of MBT in phosphate buffer with and without dissolved organic matter and in a natural water led to three products: BT (28-47%), 2-hydroxybenzothiazole (HOBT) (4-5%), and an unidentified product. On the basis of our laboratory and field results, in addition to literature reports on the occurrence of benzothiazoles, we propose a partial pathway for this family of benzothiazoles in aquatic environments. TCMTB and MBT are unlikely to persist or bioaccumulate. Stable end products appear to be BT, MTBT, and 2-hydroxybenzothiazole.
Effects of pH and humus on the availability of 2,2′,4,4′,5,5′-hexachlorobiphenyl-14C in lake water
Authors: Knulst J. C. C.
Published: March 2010

The effects of treatments of lake water with lime and acid on the availability of 2,2′,4,4′,5,5′-hexachlorobiphenyl to aquatic organisms were studied. A closed laboratory system with hexane-filled dialysis bags of two pore sizes was used, in combination with a 14C-labeled PCB isomer and liquid scintillation counting. Although the dialysis concentration factor remained relatively low throughout the experiment, a significant relationship was found between the bioavailability of polychlorinated biphenyl (PCB) and the dissolved organic carbon (DOC) content of the lake water. The availability of PCB was raised by acid and lime treatment for lake water with low DOC content, whereas both treatments lowered the availability of PCB in water from lakes with high DOC content, compared to untreated water. The liming of the lake water did result in a significantly higher bioavailability of hexachlorobiphenyl in five of the 10 tested lakes. The acidification of the lake water had a significant effect on the bioavailability of PCB in some, but not all, of the lakes. The uptake of PCB in the hexane was inversely related to the DOC concentration of the water phase. The pH does influence the bioavailability of PCB in aquatic systems with various concentrations of humus.
A multispecies laboratory microcosm for screening ecotoxicological impacts of chemicals
Authors: Sugiura Katsura
Published: March 2010

Polypeptone, Cu2+ ion, (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), β isomer of 1,2,3,4,5,6-hexachlorocyclohexane (β-HCH), and γ isomer of HCH (γ-HCH) were added to an aquatic microcosm containing green algae (Chlorella and Scenedesmus), a filamentous blue-green alga (Schizothrix), a ciliate protozoa (Cyclidium), two rotifers (Philodina and Lepadella), aquatic oligochaetes (Aeolosoma) and bacteria (five species or more) in the early stages of the succession. With a nutrient (polypeptone) at 100 to 500 ppm and 2,4,5-T at 10 to 100 ppm, some species were eliminated. No such elimination occurred from a copper concentration of up to 0.4 ppm, but the time-dependent changes in community metabolism were shifted from that of the control at the concentrations of 0.3 and 0.4 ppm. The population densities were affected by β-HCH at 0.1 to 3.0 ppm and γ-HCH at 0.01 to 5.0 ppm in the early stage of the succession, but the population densities became closer to those of the control as the succession advanced. However, time-dependent changes in community metabolism were similar to that of the control. The difference in the time-dependent changes in population density and community metabolism with the DDT addition, up to a concentration of 0.5 ppm as compared with the control, was small. It was shown that the effects of chemical agents on the microcosm can be evaluated by measuring the time-dependent changes in population density and community metabolism. Although complete evaluation must await comparative studies based on test results for other compounds, test results for other microcosms containing diverse species, and results of field experiments, it is suggested that this small-scale repeatable microcosm can be used as a tool for screening tests on generic ecosystem-level toxicity.
Groundwater modeling for an NPL risk assessment
Authors: Schuller Teresa A. , Sayko Steven P. , Desalvo Nicholas
Published: March 2010

A risk assessment for this National Priority List (NPL) site evaluated the magnitude of the public health impact, assuming that no remediation had or would occur at a landfill. The purpose of the groundwater modeling effort was to predict future groundwater concentrations after liner failure at a residential well currently using the ground water. A two-dimensional, transient, instantaneous-release, multipoint-source model was used to estimate the groundwater concentration at the residential well for 120 years after the release. A worst-case concentration in ground water was calculated by assuming that no retardation or degradation (chemical or biological) would occur. A more realistic concentration was determined by developing a retardation factor. The modeled groundwater concentrations that were simulated did not exceed standards. If no remediation were to occur and worst-case liner failure did occur, then the population would still not be at an unacceptable risk from consuming impacted ground water as a potable water supply. In reality, the predicted worst-case exposure concentrations are unlikely to be reached, and the population (i.e., few individuals) might not be exposed.
The octanol/water distribution coefficients of methylmercuric species: The role of aqueous-phase chemical speciation
Authors: Faust Bruce C.
Published: March 2010

A model is proposed that quantitatively describes the 1-octanol/water distribution coefficients of methylmercuric species in terms of the 1-octanol/water partition coefficients of each individual methylmercuric species (i.e., CH3HgCl0, CH3HgOH0, and CH3Hg+) and the aqueousphase equilibrium speciation of the methylmercuric species CH3HgCl0, CH3HgOH0, and CH3Hg+.
Response of hepatic mfo activity and plasma sex steroids to secondary treatment of bleached kraft pulp mill effluent and mill shutdown
Authors: Munkttrick K. R. M. , Van Der Kraak G. J. , McMaster M. E. , Portt C. B.
Published: March 2010

The discharge of bleached kraft mill effluent (BKME) into Jackfish Bay, Lake Superior, Canada, has been associated with a number of changes in the physiology and whole organism responses of four fish species. Current studies have been following physiological indicators of BKME impact for evidence of improvement after the installation of a secondary treatment system. Secondary treatment has not been successful in eliminating BKME impacts on hepatic mixed-function oxygenase (MFO) activity in white sucker (Catostomus commersoni) because fish collected from Jackfish Bay after initiation of secondary treatment exhibited similar MFO activity as recorded in samples collected during two previous years. Hepatic MFO activity was also induced in long-nose sucker (Catostomus catostomus), lake whitefish (Coregonus clupeaformis), and lake trout (Salvelinus namaycush) after secondary treatment. However, samples collected two weeks after a planned mill maintenance shutdown showed no MFO induction in long-nose sucker, reduced MFO activity in white sucker, and a reduced impact zone for MFO induction in lake whitefish. A reduction in circulating levels of gonadal sex steroids has also been recorded in fish exposed to primary-treated BKME in Jackfish Bay. In contrast, neither secondary treatment nor mill shutdown was sucessful in eliminating impacts of BKME exposur on levels of testosterone and 17β-estradiol in female white sucker and long-nose sucker. The short duration of MFO induction after shutdown and the peristence of steroid reductions suggest that (a) secondary treatment has not been successful in removing “MFO-active” compounds from BKME, (b) induction is not related to sediment contamination with persistent compounds, (c) the inducing agents are rapidly cleared by fish, and (d) effects on steroids may not be directly related to MFO induction.
DNA adducts detected in muskrats by 32P-postlabeling analysis
Authors: Halbrook Richard S. , Kirkpatrick Roy L. , Bevan David R. , Dunn Bruce P.
Published: March 2010

Bottom-dwelling fish from the southern branch of the Elizabeth River, Virginia, have lesions associated with exposure to environmental contaminants (primarily polycyclic aromatic hydrocarbons [PAHs]) known to be present in that reach of the river. There is concern that other wild species such as the muskrat (Ondatra zibethicus) living in the southern branch may be adversely exposed to these contaminants. DNA adducts were detected by 32P-postlabeling methods in liver tissue of muskrats collected from the southern branch of the Elizabeth River and the Nansemond River, a nearby reference river. There was no significant difference in DNA adduct concentrations in muskrats collected from the two rivers. Ten surface sediment samples collected from the southern branch of the Elizabeth River contained concentrations of 14 PAHs ranging from 1.50 to 4,233.0 ppm dry weight (total PAHs). These concentrations were significantly greater than those detected in five surface sediment samples collected from the Nansemond River (total PAHs ranged from 0.34–0.95 ppm dry weight). This is the first known study utilizing this technique to detect DNA adducts in situ in a wild terrestrial (semiaquatic) mammalian species and the first time that muskrats have been used in 32P-postlabeling analysis.