bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicity to aquatic organisms of off-target deposition of endosulfan applied by aircraft
Authors: Ernst W. R. , Jonah P. , Doe K. , Julien G. , Hennigar P.
Published: March 2010

Aerial drift from pesticide spray applications can result in contamination of nontarget environments such as aquatic systems. In this study, the off-target deposit of aerially applied endosulfan was collected on flat plate samplers and in containers of water placed at various distances downwind of the treated area. The water contaminated by that deposit was subsequently used to conduct 24-h lethal bioassays in a nearby temporary laboratory, using threespine stickleback (Gasterosteus aculeatus), water boatmen (Sigara alternata), caddisfly larvae (Limnephilus spp.), bivalve molluscs (Pisidium spp.), bloodworms (Chironomiidae spp.), and water fleas (Daphnia magna). Three different spray events were sampled, all of which occurred at times when meteorological conditions were within regulatory constraints. Chemical analysis of deposit collectors and exposed water indicated that deposit decreased in an exponential manner with distance downwind and ranged from 82 mg/m3 and 1.7 mg/L for plates and waters within the target site to 0.051 mg/m3 and 0.004 mg/L for plates and waters at 200 m downwind. After 24-h exposure to spray-drift contaminated water, no mortalities that could be attributed to the pesticide were observed for bivalve molluscs, bloodworms, or water fleas, even within the treated area. Water boatmen, caddisfly larvae, and threespine stickleback, on the other hand, suffered levels of mortality that varied directly with distance downwind from the treated area. The distances at which 50% mortality was measured in water boatmen and caddisfly larvae tests were 50 m and 10 m, respectively. Threespine stickleback were the most sensitive species tested, having a mortality of up to 90% at a distance of 200 m downwind. These results demonstrate the extreme risk to aquatic organisms from drift deposit of aerially applied endosulfan and indicate the need for similar assessments of other popular pesticides.
Behavioral responses of lake whitefish (coregonus clupeaformis) to cadmium during preference-avoidance testing
Authors: Mcnicol R. E. , Scherer E.
Published: March 2010

The behavioral responses of lake whitefish (Coregonus clupeaformis) to contact with cadmium solutions (0.2-256 μg/L) were monitored in a countercurrent-type preference-avoidance trough. A total of 27 parameters derived from 5 elements of locomotor behavior or spatial selection (including the percent-time measure) were computed and compared, and their sensitivity of response assessed. At over half of the concentrations, responses at any one concentration were dichotomous among individuals; whereas most fish showed “avoidance,” a significant number displayed “preference” when measured as the time spent on the treated side of the trough. Several of the behavioral measures displayed bimodal dose-response relationships, with a derivative of the time-spent criterion being the most sensitive indicator of response. Whitefish reacted significantly to concentrations <1 and >8 μg/L, but showed little response to those in between. They detected and responded to water containing cadmium at concentrations as low as 0.2 μg/L, the maximum allowable under Canadian water quality guidelines.
Adsorption of phenol and substituted phenols by iron oxides
Authors: McBride M. B. , Kung King-Hsi
Published: March 2010

The ability of Fe oxides to adsorb phenol and various substituted phenols from dilute aqueous solution and from the vapor state was investigated, utilizing Fourier transform infrared (FTIR) spectroscopy to evaluate the type of surface complex formed. Adsorption from solution at pH 5.5 was weak (undetectable in the case of the unsubstituted phenol). There was some indication that quantity of adsorption was inversely related to the pKa of the p-substituted phenols, with the most acidic phenols adsorbing the most strongly from solution. The FTIR spectra revealed that adsorption on goethite and amorphous Fe oxide from the vapor state tended to perturb vibrational bands sensitive to the phenolic OH group, an indication of bonding between surface Fe3+ and the phenolic ligand. Depending on level of adsorption, both physically and chemically adsorbed phenols could be detected by FTIR with chemisorption being more in evidence on amorphous Fe oxide. Phenol that was 2,6-methyl-disubstituted failed to interact strongly with the goethite surface, suggesting that steric hindrance from groups adjacent to the phenolic group prevented inner-sphere coordination of the phenols to surface Fe atoms. This steric effect was not evident for low levels of adsorption on amorphous Fe oxide, suggesting an important role of site geometry in limiting chemisorption. The strength of the Fe3+-phenolic coordination bond was correlated to the pKa of the phenol, with more acidic phenols forming weaker CO bonds. The quantity of water present determined whether the phenols adsorbed at barely detectable or much higher levels, suggesting a competition between H2O and phenols for ligand positions of surface Fe.
The biodegradation of methylene chloride in soils
Authors: Davis John W. , Madsen Steve S.
Published: March 2010

The aerobic biodegradation of methylene chloride was observed in a variety of surface soils including a sand, a sandy loam and a sandy clay loam, as well as a subsurface clay soil. Degradation was found to occur over concentrations ranging from approximately 0.1 ppm to 5.0 ppm. Degradation at higher concentrations was facilitated by the presence of an exogenous organic carbon source. No products other than carbon dioxide were detected in the biologically active microcosms. The time required for 50% disappearance of the parent compound varied over 100-fold, ranging from 1.3 to 191.4 d. Preexposure of the soil to methylene chloride resulted in faster rates of degradation upon subsequent exposures. Methylene chloride degradation was also observed under anaerobic conditions in the sandy loam soil. In contrast to observations under aerobic conditions, a significant lag or acclimation period preceded biodegradation under anoxic conditions, and no loss of the parent compound was observed during the first 70 d. However, following the lag period, the rate of degradation was approximately 10-fold higher under anaerobic conditions.
Early postnatal exposure to PCBs: Sperm function in rats
Authors: Sager D. , Girard D. , Nelson D.
Published: March 2010

Our previous studies have found that early exposure to polychlorinated biphenyls (PCBs) through milk of the dam can affect fertility when male offspring reach adulthood. A significant proportion of ovulated eggs in normal females mated to PCB-exposed males do not implant. This effect does not appear to be related to reduced weight gain of pups during PCB exposure. In this study, dams with litters were given peanut oil or a PCB mixture (Aroclor 1254) in oil at doses of 8, 16, 32 and 64 μg/g (PCBI, II, III, IV) on days 1,3,5,7 and 9 of lactation. At 120 d of age the male offspring were mated to normal females. Oviducts/uteri of sperm-positive females were flushed and eggs examined at the expected pronuclear, two- to four-cell and blastocyst stages of development. We observed either a significant decrease or a decline in number and percent of normal fertilized eggs and eggs at the two- to four-cell and blastocyst stages in females mated to male offspring of PCBII, III and IV. Neither reduced ventral prostate weights nor an increased incidence of a right kidney abnormality were correlated with reduced fertility. Caudal sperm reserves, sperm production, epididymal sperm morphology and FSH levels were not affected; testosterone levels were not reduced as compared to those of controls. With one exception, epididymal sperm motility parameters were not significantly different. It appears that early postnatal exposure to PCBs affects ability of sperm to fertilize eggs but not production, morphology or motility of epididymal sperm.
Effects of exposure to carbofuran-sprayed vegetation on the behavior, cholinesterase activity and growth of mallard ducklings (anas platyrhynchos)
Authors: Martin Pamela A. , Solomon Keith R. , Forsyth Douglas J. , Boermans Herman J. , Westcott Neil D.
Published: March 2010

Mallard (Anas platyrhynchos) ducklings were led for distances of 50, 150 and 300 m through plots of upland vegetation that had been sprayed with a flowable formulation of carbofuran at rates of 0, 132 and 264 g active ingredient/ha. Duckling behavior was observed and quantified immediately after exposure by using an approach-response apparatus. Brain and plasma cholinesterase (ChE) activities were determined for a subsample of ducklings from each treatment group; the remaining ducklings were monitored for growth effects. No mortality occurred during field exposure, but toxic signs were observed in ducklings moving < 150 m at both spray rates. At > 150 m, 17 and 100% of the ducklings had difficulty keeping pace due to anti-ChE toxicosis in the low and high spray plots, respectively. Duckling approach-response behavior became significantly slower with increasing spray rate and exposure distance (p = 0.0001). Inhibition of brain ChE activity was directly related to both spray rate and exposure distance; ducklings receiving maximum carbofuran exposure had 29% of the mean ChE activities of controls. Plasma ChE activity was inversely related to spray rate but was not affected by exposure distance and did not correlate well with brain ChE activity (R2 = 0.36). Subsequent growth rates were not affected in a dose-related manner.
Acute toxicity of four anticholinesterase insecticides to American kestrels, eastern screech-owls and Northern Bobwhites
Authors: Wiemeyer Stanley N. , Sparling Donald W.
Published: March 2010

American kestrels (Falco sparverius), eastern screech-owls (Otus asio), and northern bobwhites (Colinus virginianus) were given single acute oral doses of four widely diverse anticholinesterase pesticides: EPN, fenthion, carbofuran, and monocrotophos. LD50s, based on birds that died within 5 d of dosage, were computed for each chemical in each species. Sex differences in the sensitivity of northern bobwhites in reproductive condition were examined. American kestrels were highly sensitive to all chemicals tested (LD50s 0.6–4.0 mg/kg). Eastern screech-owls were highly tolerant to EPN (LD50 274 mg/kg) but sensitive to the remaining chemicals (LD50s 1.5–3.9 mg/kg). Northern bobwhites were highly sensitive to monocrotophos (LD50 0.8 mg/kg) and less sensitive to the remaining chemicals (LD50s 4.6–31 mg/kg). Female bobwhites (LD50 3.1 mg/kg) were more sensitive to fenthion than males (LD50 7.0 mg/kg). Mean percent depression of brain cholinesterase (ChE) of birds that died on the day of dosing exceeded 65% for all chemicals in all species. The response of one species to a given pesticide should not be used to predict the sensitivity of other species to the same pesticide. The need for research on several topics is discussed.
The role of acid-volatile sulfide in determining cadmium bioavailability and toxicity in freshwater sediments
Authors: Carlson Anthony R. , Phipps Gary L. , Mattson Vincent R. , Kosian Patricia A. , Cotter Anne M.
Published: March 2010

The objective of this study was to determine if the acid-volatile sulfide (AVS) content of freshwater sediments was important in limiting the bioavailability and toxicity of cadmium. Five different concentrations of cadmium were spiked into sediments with three different AVS concentrations, and 10-d exposures with the oligochaete Lumbriculus variegatus and the snail Helisoma sp. were conducted. Concurrent water-only cadmium exposures were also conducted. When the cadmium-to-AVS ratios were ≤1, toxicity was not observed. At ratios ≤1, mean whole-body cadmium residue concentrations of organisms were approximately equal to or less than the maximum residues obtained in survivors of the cadmium exposures in water only. These results corroborated the results of a previous experiment conducted with saltwater sediments and indicate that metal/AVS relationships could be used to establish numeric sediment quality criteria for use in the protection of aquatic life.
The lethal and sublethal responses of gammarus pulex to stress: Sensitivity and sources of variation in an in situ bioassay
Authors: Crane Mark , Maltby Lorraine
Published: March 2010

The feeding rate and mortality of the freshwater amphipod Gammarus pulex L., a common benthic detritivore, were measured during four trials of an in situ bioassay. The Gammarus pulex were deployed in a factorial experiment designed to assess the effects of water quality (three stations), test population (two sources), and test operator (two laboratories). Stations were selected above and below a domestic sewage treatment works, a sewage treatment works processing domestic and industrial waste, a quarry, and a pulp mill. Feeding rate appeared to have potential as an indicator of water quality, but the source of the test population and the laboratory performing the measurements both significantly influenced the results.
Predicting chemical reactivity by computer
Authors: Karickhoff Samuel W. , Mcdaniel Valeta K. , Melton Clyde , Vellino Andre N. , Nute Donald E. , Carreira Lionel A.
Published: March 2010

Mathematical models for predicting the fate of pollutants in the environment require reactivity parameter values —that is, the physical and chemical constants that govern reactivity. Although empirical structure-activity relationships have been developed that allow estimation of some constants, such relationships generally hold only within limited families of chemicals. Computer programs are under development that predict chemical reactivity strictly from molecular structure for a broad range of molecular structures. A prototype computer system called SPARC (SPARC Performs Automated Reasoning in Chemistry) uses computational algorithms based on fundamental chemical structure theory to estimate a variety of reactivity parameters (e.g., equilibrium/rate constants, UV-visible absorption spectra, etc.). This capability crosses chemical family boundaries to cover a broad range of organic compounds. SPARC does not do “first principles” computation, but seeks to analyze chemical structure relative to a specific reactivity query in much the same manner in which an expert chemist would do so. Molecular structures are broken into functional units with known intrinsic reactivity. This intrinsic behavior is modified for a specific molecule in question with mechanistic perturbation models. To date, computational procedures have been developed for UV-visible light absorption spectra, ionization pKa, hydrolysis rate constants, and numerous physical properties. This paper describes the logic of the approach to chemistry prediction and provides an overview of the computational procedures. Additional papers are in preparation describing in detail the chemical models and specific applications.
The effect of temperature on cadmium kinetics and oxygen consumption in soil arthropods
Authors: Janssen Martien P.M. , Bergema Walter F.
Published: March 2010

Soil arthropod species differ considerably in cadmium concentration and the way their burdens vary seasonally. The seasonal variation is often explained by variation in temperature and metabolic activity. To estimate the distribution of cadmium over the soil community and its annual fluxes through the different species, temperature responses of cadmium kinetics have to be taken into account.

We examined the effect of temperature on consumption, number of fecal pellets, oxygen consumption, and cadmium kinetics in two common soil arthropod species, Platynothrus peltifer and Orchesella cincta. Accumulation and elimination of cadmium was analyzed by fitting a one-compartment model. Oxygen consumption was higher for Orchesella cincta than for Platynothrus peltifer. Consumption and number of fecal pellets increased considerably between 10 and 20°C. Oxygen consumption increased exponentially in both species.

Cadmium kinetics of the species showed a different response to temperature. In Orchesella cincta, assimilation and excretion increased with temperature; in Platynothrus peltifer, assimilation increased with temperature whereas no effect was found for excretion. As a result, the equilibrium concentration remained constant in Orchesella cincta, whereas in Platynothrus peltifer it increased between 10 and 20°C.

The results indicate that the effects of temperature on cadmium kinetics differ among soil arthropod species and that it is difficult to extrapolate results from one species to the whole soil arthropod community. Species equipped to store cadmium internally seem to respond in a more pronounced way to increased temperature than do species equipped to rapidly excrete cadmium. Because oxygen consumption and cadmium kinetics are not directly related, temperature responses of cadmium kinetics should be taken into account in calculating fluxes of metals through soil arthropod populations.
Lead concentrations in wing bones of the mottled duck
Authors: Merchant Mark E. , Shukla Shyam S. , Akers Hugh A.
Published: March 2010

Wing samples from mottled ducks (Anas fulvigula) were collected from federal, state, and private hunting areas in Texas, Louisiana, and Florida during the 1987–1988 waterfowl season. The upper wing bone (humerus) was analyzed for lead content to determine long-term exposure of each bird to lead. Comparisons were made between mean lead concentrations found in males and females, in adults and immatures, and between mottled ducks from different areas. In general, males and adult ducks were found to contain greater lead concentrations than females and immature ducks, respectively. Of the six areas considered, Anahuac National Wildlife Refuge, Texas, was observed to have the greatest (88.9 ppm dry weight basis) and private areas in St. Bernard Parish, Louisiana, found to have the lowest (27.9 ppm) concentrations of lead. The results from this study were found to be comparable to those obtained from a similar study performed during the 1972–1973 waterfowl season.
Population-, community- and ecosystem-level responses of aquatic mesocosms to pulsed doses of a pyrethroid insecticide
Authors: Fairchild James F. , La Point Thomas W. , Zajicek James L. , Nelson Marcia K. , Dwyer F. James , Lovely Phillip A.
Published: March 2010

Population-, community-, and ecosystem-level responses to pulsed dosing of a pyrethroid insecticide were studied in experimental aquatic mesocosms. Twelve mesocosms (0.1 ha, 700 m3 volume) were dosed with technical-grade esfenvalerate dissolved in acetone (subsurface injection of 0-, 0.25-, 0.67-, or 1.71-μg/L nominal concentrations in triplicated mesocosms) on six dates at two-week intervals. We monitored dissipation rate of esfenvalerate; survival, growth, and reproduction of bluegill (Lepomis macrochirus); dynamics of benthos and zooplankton; biomass and productivity of phytoplankton; macrophyte biomass; diurnal oxygen pulse; and water quality over a five-month interval. Esfenvalerate dissipated rapidly from the water column (half-life, 10 h). Zooplankton and benthic macroinvertebrates decreased at 0.25 μg/L. Changes in invertebrate fauna due to esfenvalerate were partly obscured by indirect effects and seasonal dynamics. Bluegill survival, biomass, adult male survival, and reproductive success were negatively correlated with measured esfenvalerate concentrations. Although direct mortality of fish and invertebrates may be predictable from laboratory single-species tests, indirect responses of fish, zooplankton, and phytoplankton are predictable only with prior knowledge of factors controlling ecosystem structure and function.
Lethal and sublethal toxicity of benzene derivatives to the fathead minnow, using a short-term test
Authors: Marchini Silvia , Tosato Maria L. , Norberg-King Teresa J. , Hammermeister Dean E. , Hoglund Marilynn D.
Published: March 2010

The lethal and sublethal effects of six monosubstituted derivatives of benzene (MBs) were measured by using the 7-d test with fathead minnow larvae. The LC50s for larvae were compared to those derived from the acute test. The larvae were more sensitive than juvenile fish, yet the toxicity order of MBs was the same for both life stages, that is, butylphenylether > benzophenone > toluene = benzene > nitrobenzene > aniline. The slopes of the concentration–mortality curves indicate a peculiar behavior for aniline.

The no-observed-effect concentrations (NOECs) and the lowest-observed-effect concentrations (LOECs) for survival and growth, obtained from hypothesis test statistics, are reported together with the inhibition concentrations (ICs) for growth and biomass, calculated with a point estimation technique. The performance of the two different statistical approaches in providing adequate data for toxicity assessment is evaluated. Growth was a more or equally sensitive end point than survival, and for three chemicals biomass was more sensitive than growth.

The results of the 7-d test are compared with those of the early life stage (ELS) test. The short-term test gave the same estimates of chronic toxicity as the ELS test for benzophenone, toluene, and benzene. The toxicity of aniline was underestimated, especially with respect to growth effects.
Effects of elevated selenium concentrations on bluegills (lepomis macrochirus) in outdoor experimental streams
Authors: Hermanutz Roger O. , Allen Kathleen N. , Roush Thomas H. , Hedtke Steven F.
Published: March 2010

Replicated outdoor experimental streams were exposed to control water and 10 and 30 μg/L selenium (introduced as sodium selenite) to evaluate whether standard laboratory test results accurately predict the effects of selenium on fish in freshwater ecosystems and to evaluate effects found in field studies as reported in the literature. Effects on the survival, growth, and reproduction of bluegill sunfish and the early life stage of their progeny were the end points measured in a 356-d study. Adult bluegills exposed to 10 μg/L had survival reductions (p ≤ 0.05) during the final 98-d period, and those exposed to 30 μg/L experienced complete mortality. Adult growth was reduced at 10 μg/L during an intermediate period (p ≤ 0.05). Exposures of adults at both 30 and 10. μg/L for 40 weeks before spawning resulted in reduced embryo and larval survival and produced larvae with a high incidence of edema, lordosis, and internal hemorrhaging (not all were statistically significant at p ≤ 0.05). This study confirms that standard laboratory tests, which expose fish only through the water pathway, have underestimated the toxicity of selenium, and that 10 μg/L of selenium in the water of a natural ecosystem may adversely affect bluegills, as concluded by other investigators in several field studies.
A pharmacokinetic analysis of the uptake of polychlorinated biphenyls (PCBs) by golden shiners
Authors: Karara Adel H. , Mcfarland Victor A.
Published: March 2010

A 96-h, static, nonconstant exposure design was used to assess pharmacokinetic parameters and to identify the rate-limiting process in polychlorinated biphenyl (PCB) uptake by golden shiners (Notemigonus crysoleucas). Fish were exposed individually to 14C-labeled PCBs corresponding to Aroclor 1254 (A1254). After various intervals (2–96 h), fish and water were analyzed for total radioactivity. Uptake of PCBs and decline of the external water concentration were both rapid. A clearance constant-based one-compartment model was used to represent the fish. Model-based equations for PCB concentrations in the fish and in the water were fitted simultaneously to the observed data with the PCNONLIN™ computer program. The absorption clearance constant was 30.8 ml·h−1·g−1 fish, which identified gill blood flow as the uptake rate-controlling process. The model-predicted apparent volume of distribution, Vd, and bioconcentration factor, Kb, were 5,280 ml/g fish and 9,059 ml water per gram fish, respectively. The model-predicted elimination rate constant, ke, was 5.84 × 10−3h−1, corresponding to a t1/2 of 4.9 d.
Evaluation of EPA's rapid bioassessment benthic metrics: Metric redundancy and variability among reference stream sites
Authors: Barbour Michael T. , Graves Carol G. , Plafkin James L. , Wisseman Robert W. , Bradley Brian P.
Published: March 2010

The data analysis scheme used in the U.S. Environmental Protection Agency's (EPA's) rapid bioassessment protocols (RBPs) integrates several community, population, and functional parameters (or metrics) into a single assessment of biological condition. A reference data base of macroinvertebrate data obtained from 10 ecoregions in Oregon, Colorado, and Kentucky was used to evaluate the appropriateness and variability of the benthic metrics and the similarities of results among ecoregions. Several statistical procedures, including principal component analysis, correlation coefficient, analysis of variance, and stepwise discriminant analysis, were used to test the efficacy of 17 community metrics. A general separation between the mountain ecoregions and the valley/plains ecoregions was determined to exist for the metrics. Two of the original eight metrics described in the EPA's RBPs for benthic macroinvertebrates were found to be highly variable and unreliable as measures of biological conditions in some ecoregions. Eleven metrics were determined as being valuable in discriminating between montane and valley/plains groupings of ecoregions.
Predictive model for aerobic biodegradability developed from a file of evaluated biodegradation data
Authors: Howard Philip H. , Stiteler William M. , Meylan William M. , Hueber Amy E. , Beauman Julie A. , Larosche Michael E. , Boethling Robert S.
Published: March 2010

A file of evaluated biodegradation data was used to develop a model for predicting aerobic biodegradability from chemical substructures. Chemicals initially were divided into three groups: (a) chemicals that degrade rapidly under most environmental conditions without requiring acclimation; (b) chemicals that are biodegradable, but only after an acclimation period; and (c) chemicals that degrade slowly or not at all. Chemicals in the first and last groups were then used to develop a model for classifying chemicals as rapidly biodegradable or not rapidly biodegradable. Two models, one based on linear regression and the other based on nonlinear regression, were developed from 35 preselected substructures. Both models predict the biodegradation categories correctly 90% of the time for the training set (264 chemicals) and an independent validation set (27 chemicals), and are 95% correct for chemicals that biodegrade rapidly.
Emerging insects as a biotic pathway for movement of 2,3,7,8-tetrachlorodibenzofuran from lake sediments
Authors: Fairchild Wayne L. , Muir Derek C. G. , Currie Robert S. , Yarechewski Alvin L.
Published: March 2010

Emerging insects are a potential biotic transport route for export of contaminants sequestered in lake sediments to surrounding aquatic and terrestrial ecosystems Emerging insects (mainly Diptera) were collected from four lake mesocosms treated with 10 μg of sediment-sorbed 2,3,7,8-tetrachlorodibenzofuran Insects emerging from the mesocosms had a mean contaminant concentration of 228 pg/g wet weight Contaminant export by emerging insects was from 0 2 to 2 1% of the total sediment contaminant content annually
QSARs based on fuzzy adaptive least-squares analysis for the aquatic toxicity of organic chemicals
Authors: Liu Qian , Hirono Shuichi , Matsushita Yasuo , Moriguchi Ikuo
Published: March 2010

A quantitative structure-activity relationship (QSAR) model for the prediction of aquatic toxicity of organic chemicals was formulated. Toxicity data of 394 compounds with a wide variety of structures were collected from a data base and other literature. The molecular structures were quantitatively described, using substructural and hydrophobic parameters for the QSAR analysis. Fuzzy adaptive least-squares (FALS), a pattern recognition method recently developed at our laboratory, was used in the QSAR study. A discriminant function with 37 variables was obtained, representing satisfactorily the correlation of structure with aquatic toxicity ratings of compounds. The results were highly significant both in recognition and in leave-one-out prediction.
Quantitative modeling of environmental fate and impact of commercial chemicals
Authors: Sabljić Aleksandar , Piver Warren T.
Published: March 2010

Present laws in many countries require that all commercial chemicals be assessed for their environmental behavior and hazards. Because there are a large number of chemicals currently in common use (approximately 100,000) and new chemicals are being registered at a very high rate (1,000 per year), it is obvious that our human and material resources are insufficient to obtain experimentally even basic information about environmental fate and effects for all these chemicals. Thus, it is necessary to develop quantitative models that will accurately and rapidly predict environmental behavior for large sets of chemicals. During the last decade, a considerable effort has been made to develop methods that use molecular characteristics to describe environmental behavior of organic pollutants. Thus far, molecular connectivity indexes have been shown to be the most successful structural property for describing and predicting soil sorption coefficients, association coefficients with dissolved humic substances, Henry's law constants, bioconcentration factors in aquatic organisms and vegetation, biodegradation rates, and fish acute toxicity. The general quantitative model, based on the first-order molecular connectivity index (MCI), has been developed for the accurate estimation of soil sorption coefficients for predominantly hydrophobic chemicals: polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), halogenated hydrocarbons, and phenols. It is possible to extend this model for many classes of agricultural chemicals. A similar model, based on the second-order valence MCI, has been developed for fish bioconcentration factors of PCBs, chlorinated diphenyl oxides, halogenated hydrocarbons, PAHs, and phenols, plus substituted benzenes. Furthermore, a prototype expert system has been developed for classifying untested chemicals as readily or not readily biodegradable, based on their chemical structures. Finally, using a standardized data base for fish acute toxicity, we have obtained a simple linear correlation between the valence zero-order MCI and the 96-h LC50 data for a large group of 150 structurally diverse commercial chemicals.
An evaluation of nickel toxicity to Ceriodaphnia dubia and Daphnia magna in a contaminated stream and in laboratory tests
Authors: Kszos Lynn Adams , Stewart Arthur J. , Taylor Paul A.
Published: March 2010

Seven-day tests with Ceriodaphnia dubia were used to document ambient toxicity in two industrially contaminated streams in southeastern Tennessee. Low survival of Ceriodaphnia dubia was linked to concentrations of Ni (74-200 μg/L) below Environmental Protection Agency (EPA) water quality criteria. A toxicity identification evaluation consisting of Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas (fathead minnow) toxicity tests with Ni, chemical analyses, and experiments with a Ni-selective resin were used to show that Ni was the primary toxicant in one of the streams. Nickel nitrate and Ni chloride were both extremely toxic to Ceriodaphnia dubia but were not very toxic to Pimephales promelas: Ni at a concentration of 7.5 μg/L (water hardness, 40 mg/L as CaCO3) was lethal to Ceriodaphnia dubia within 7 d, but 16 mg/L Ni did not reduce survival or growth of Pimephales promelas. When dilution water with a hardness of 177 mg/L was used, 15.0 μg/L killed all the Ceriodaphnia dubia in 7 d (no reduction in survival or fecundity occurred in 7.5 μg/L). Daphnia magna was less sensitive than Ceriodaphnia dubia to Ni: A concentration of 40 μg/L significantly reduced fecundity but not survival in 21 d. In stream water containing 49 μg/L Ni (hardness, 656 mg/L), 100% mortality of Ceriodaphnia dubia occurred in 7 d, but 70% of the Daphnia magna survived for 14 d. When the Ni in the stream water was reduced to 10 μg/L with the resin, 60% of the Ceriodaphnia dubia lived for 7 d and all the animals reproduced; survival and reproduction of Daphnia magna remained high for all 14 d. Thus, in both ambient water and pure chemical tests, Ceriodaphnia dubia was found to be much more sensitive to Ni than Daphnia magna. Experiments with 63Ni showed that both species accumulated similar amounts of Ni, so the difference in toxicity was not a result of Ni uptake. The high sensitivity of Ceriodaphnia dubia to Ni and the lower than expected reduction in Ni toxicity to Ceriodaphnia dubia with increasing hardness have important implications for effluent and ambient testing and toxicity reduction efforts.
An overview of global warming
Authors: Mohnen Volker A. , Wang Wei-Chyung
Published: March 2010

Temperature records indicate that the global annual mean surface air temperature (referred to as the global temperature) has risen by 0.5°C since 1840. According to recent general circulation model calculations, by the year 2020 the global mean temperature will have risen to 1.3 to 2.5°C above the preindustrial (1840) mean. By the year 2070, the range of temperature increase will be 2.4 to 5.1°C, and sea level will have risen 33 to 75 cm. Measurements from Antarctic ice cores show temperature swings of 4 to 5°C between ice ages and interglacial periods. Fossil fuel-based energy use through power generation and transportation is viewed as the major cause of the very recent and projected future temperature rise. Recent arguments of scientists and policy makers have increasingly focused on the exact scope of global-scale changes and consequences of the globally rising energy appetite. The question of global warming has become the most important scientific issue.
Impact of ozone on loblolly pine seedling foliage production and retention
Authors: Kress Lance W. , Lee Allen H. , Mudano Jane E. , Stow Tara K.
Published: March 2010

Field-grown one-year-old loblolly pine seedlings were exposed to a complete factorial design of ozone and acidic precipitation in open-top chambers for two seasons. Foliage production and retention were evaluated during the second exposure season. Five ozone exposures ranging from 0.42 to 2.95x ambient and two rainfall treatments, pH 5.3 and pH 3.3, were applied for two growing seasons. Fascicle number and length of early season flushes were decreased by increasing ozone, but ozone increased fascicle length of late season flushes. Foliage retention was significantly decreased as ozone concentration increased. A significant reduction in fascicle retention was observed at ambient ozone concentrations. Significant pine family differences were noted for many of the evaluated foliage variables. Acidic precipitation generally had no significant effects, except that overall branch foliage retention tended to increase with increasing acidity and there was an ozone by rain acidity interaction when 1987 branch foliage was evaluated. Decreased foliage retention may be a partial explanation for the growth rate reductions in some stands in the Southeast.
Evaluating the statistical bases for relating receiving water impacts to effluent and ambient toxicities
Authors: Marcus Michael D. , McDonald Lyman L.
Published: March 2010

The U.S. Environmental Protection Agency's Complex Effluent Toxicity Testing Program (CETTP) investigated the relationship of ecological conditions in eight receiving water systems to toxicities in both discharged effluents and ambient receiving waters. Our evaluation of the CETTP studies showed that they included no statistical evaluation of relationships between effluent toxicity and instream effects. We found that (a) limitations in the designs for these studies prevented statistically based inferences using relationships reported between ambient toxicity and instream impacts to other sites or to other times at these sites; (b) relatively few significant correlations existed between pairs of ambient toxicity and instream community variables; (c) the CETTP method for correlating maximum ambient toxicity to maximum instream impact generally reduced correlation between pairs of variables; and (d) the CETTP method used to show percentages of “correct predictions” by laboratory toxicity projections of instream impacts was mathematically biased and inappropriate. We show that canonical correlation analysis is a potentially useful approach for evaluating relationships between matrices of laboratory toxicity and field community measures. Our results indicate that the short-term chronic test results for ambient waters can potentially provide useful information relating to biological community structure in streams where toxicity is a predominating habitat influence.
Enhancement to the pielou method for estimating the diversity of aquatic communities
Authors: Clark Malcolm John Roy
Published: March 2010

The Pielou abundance ratio method of estimating the diversity of aquatic communities by plotting the relative abundances of the three most common species per sample on ternary plots has been further developed. Algorithms are presented that permit the ternary plots to be readily produced via any computer spreadsheet having orthogonal graphics capability. The Pielou method is modified to present time-series-diversity data as chronological tables or plots similar to those used for other water-quality variables and to accommodate n-dimensional relationships. The modified method is applied to phytoplankton data from two lakes, one impacted by acid mine drainage and one pristine.
Temperature dependence of henry's law constants for selected chlorobenzenes, polychlorinated biphenyls and polycyclic aromatic hydrocarbons
Authors: Hulscher Th.E. M. Ten , Van Der Velde L. E. , Bruggeman W. A.
Published: March 2010

Modeling the fate of organic micropollutants in aquatic systems requires information about gas/water partitioning at environmental temperatures. In this paper experimental data are presented on Henry's law constant (H) for seven chlorobenzenes, three polychlorinated biphenyl (PCB) congeners, and six polycyclic aromatic hydrocarbons (PAHs). The studied compounds were 1,2,3–; 1,2,4– and 1,3,5–tri–; 1,2,3,4– and 1,2,3,5–tetra–; penta–; and hexachlorobenzene; 2–5–di–; 2,4,4′–tri-; and 2,2′5,5′–tetrachlorobiphenyl; and the PAH compounds fluoranthene, benzo[b]flu-oranthene, benzo[kfluoranthene, benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3–cd]pyrene. H was measured in a buffer solution using a modified gas-purge technique. Values for this set of PAH compounds have not been determined experimentally before. The temperature dependence of H was measured for the tetra-, penta-, and hexachlorobenzenes and for all PCBs and PAHs over a temperature range of 10 to 55°C. The experimental data and temperature dependence are in good agreement with partitioning theory and available literature data. The observed temperature dependence results in a doubling of H for every 10°C temperature increase.
Modeling pesticide movement in forested watersheds: Use of przm for evaluating pesticide options in loblolly pine stand management
Authors: Dowd J.F. , Bush P.B. , Berisford Y.C. , Neary D.G. , Taylor J.W.
Published: March 2010

The fate of pesticides in forest ecosystems is strongly influenced by climatic conditions. Drought or excessive rainfall may seriously affect dissipation rates, routes, and the extent of movement through soil profiles. The pesticide root zone model (PRZM) is designed to predict pesticide movement in unsaturated soils within and below the plant root zone in agricultural systems. The applicability of this model to a forested watershed was tested by using on-site hydrologic data to simulate a field application of lindane. PRZM-predicted data were compared with measured residue levels and found to estimate accurately lindane movement and leaching at shallow soil depths (0-10 cm), but underestimated residue levels at deeper soil depths (40-50 cm). Model simulations were used to evaluate various insecticide and herbicide application scenarios used in pine plantation management. Results from these simulations indicate that insecticides commonly used for gypsy moth (Lymantria dispar L.) or southern pine beetle (Dendroctonus frontalis Zimm.) control either are not sufficiently persistent or are adsorbed in the soil to such an extent that they do not pose a potential groundwater contamination problem. In contrast, site preparation herbicides show a potential to leach whenever proper meteorological conditions such as rainfall prevail after application. These herbicides are persistent (t1/2 > 50), moderately adsorbed (10 > Kd > 0.1, assuming 1.7% organic matter), and applied under conditions of reduced evapotranspiration.
Comparison of FSCBG spray model predictions with field measurements
Authors: Rafferty James E. , Bowers James F.
Published: March 2010

The FSCBG (Forest Service, Cramer, Barry, and Grim) aerial spray model was developed under joint sponsorship of the U.S. Army and the USDA Forest Service to predict concentration, dosage, and deposition patterns of spray material downwind from aerial releases. A new version of the model incorporates the AGDISP model, which provides a much more rigorous mathematical description of wake effects on drop trajectories than the simple wake effects algorithm of the original FSCBG model. This paper describes graphical and statistical comparisons of deposition measurements from two field programs with model predictions using (a) no wake effects, (b) the simple wake effects of the original model, and (c) the AGDISP (agricultural dispersal) wake effects of the new model. All model versions showed skill in reproducing observed deposition profiles for both data sets. The inclusion of complex wake effects qualitatively improved the correspondence between predictions and measurements in the vicinity of the peak deposition for inwind releases and at the longer downwind distances for crosswind releases. However, statistical performance measures were inconclusive in quantifying this improvement.
Anaerobic dechlorination of aroclor 1242 as affected by some environmental conditions
Authors: Rhee G.-Yull , Bush B. , Sokol R.C. , Bethoney C.M. , DeNucci A. , Oh H.-M.
Published: March 2010

The effect of electron acceptors and biphenyl on reductive dechlorination was investigated using the commercial polychlorinated biphenyl mixture Aroclor 1242 and sediment microorganisms from the Hudson River. Polychlorinated biphenyl- (PCB-) free sediments spiked with the Aroclor at 700 μg/g and anaerobically incubated for six months, with and without biphenyl enrichment, showed that dechlorination was most advanced with CO2 without biphenyl enrichment. A small amount of methane was detected. However, methane production per se was not essential for dechlorination, because addition of the inhibitor of methane production, 2-bromoethane sulfonate, did not affect dechlorination. On the other hand, dechlorination was inhibited partly by sulfate and completely by nitrate. Biphenyl enrichment initially inhibited dechlorination under both methanogenic and sulfidogenic conditions.
Biotransformation of organophosphorus compounds by rainbow trout (Oncorhynchus mykiss) liver in relation to bioconcentration
Authors: De Bruijn Jack , Seinen Willem , Hermens Joop
Published: March 2010

Biotransformation of a series of organophosphorus compounds by the 9,000-g supernatant of rainbow trout (Oncorhynchus mykiss) liver was tested in an in vitro system fortified either with NADPH-generating cofactors or with reduced glutathione (GSH). Elimination rate constants for both systems were calculated from linear decay curves when substrate concentrations were used that were considerably lower than the Km values of the concerned enzymatic reactions. The results reveal a large variation in both the oxidative and the glutathione-mediated biotransformation rate of the organophosphorus compounds. Half-lives ranged from 25 to 1,216 min in the NADPH system and from 18 to 381 min in the GSH system. Elimination rate constants in the GSH system were related to Hammett σ constants or reactivity toward 4-nitrobenzylpyridine, which substantiates the assumption that electrophilicity is the controlling variable for the reaction with GSH within this particular class of compounds. A remarkable analogy was observed between compounds that were metabolized relatively quickly by glutathione S-transferases and compounds that showed a reduced bioconcentration factor in guppies. A significant improvement of the relationship between the bio-concentration factor in guppies and the octanol/water partition coefficient was obtained when the rate constant with GSH was introduced in this relationship. Such an improvement was not obtained with the rate constants from the oxidative system. These observations are discussed in view of the differences in the activities of the involved enzyme systems in the test species and in view of the possible relevance of the different biotransformation pathways for the in vivo situation.
Impacts of UV radiation and photomodification on the toxicity of pahs to the higher plant Lemna gibba (duckweed
Authors: Huang Xiao-Dong , Dixon D. George , Greenberg Bruce M.
Published: March 2010

The toxicity of polycyclic aromatic hydrocarbons (PAHs) can be enhanced by both biotic and abiotic processes. This is exemplified by light, which, by virtue of the extensive π-orbital systems of PAHs, can be a major factor in PAH toxicity. Light activation of PAHs is known to occur via photosensitization reactions (generation of singlet oxygen and superoxide) and potentially by photomodification of the chemicals (photooxidation and/or photolysis) to more toxic species. To examine the modes of PAH action in the light and determine if the photomodified compounds are hazardous, we investigated the photoinduced toxicity of anthracene, phenanthrene and benzo[a]pyrene to the aquatic higher plant Lemna gibba (a duckweed). Toxicity end points were inhibition of growth and extent of chlorosis. Light did indeed activate the phytotoxicity of PAHs, with UV radiation more effective than visible light. Dose-response curves based on chemical concentration and light intensity revealed the order of phytotoxic strength to be anthracene > phenanthrene > benzo[a]pyrene. To explore whether photomodified PAHs were contributing to toxicity, the chemicals were irradiated before toxicity testing. The rates of photomodification of the three PAHs were rapid (half-lives in hours), and the relative velocities were coincident with the order of toxic strength. Furthermore, the photomodified PAHs were more hazardous to Lemna than the intact compounds. Because interpretations of the potential impacts of PAHs in the environment are based mostly on measurements of the structurally intact chemicals, the severity of PAH hazards is possibly underestimated.