bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of chemical fate in the environment using evaluative, regional and local-scale models: Illustrative application to chlorobenzene and linear alkylbenzene sulfonates
Authors: Mackay Donald , Di Guardo Antonio , Paterson Sally , Kicsi Gabriel , Cowan Christina E. , Kane David M. 
Published: March 2010

Abstract
Evaluation of chemical fate in the environment has been suggested to be best accomplished using a five-stage process in which a sequence of increasing site-specific multimedia mass balance models is applied. This approach is illustrated for chlorobenzene and linear alkylbenzene sulfonates (LAS). The first two stages involve classifying the chemical and quantifying the emissions into each environmental compartment. In the third stage, the characteristics of the chemical are determined using the evaluative equilibrium criterion model, which is capable of treating a variety of chemicals including those that are involatile and insoluble in water. This evaluation is conducted in three steps using levels I, II, and III versions of the model, which introduce increasing complexity and more realistic representations of the environment. In the fourth stage, ChemCAN, which is a level III model for specific regions of Canada, is used to predict the chemical's fate in southern Ontario. The final stage is to apply local environmental models to predict environmental exposure concentrations. For chlorobenzene, the local model was the SoilFug model, which predicts the fate of agro-chemicals, and for LAS the WW-TREAT, GRiDS, and ROUT models were used to predict the fate of LAS in a sewage treatment plant and in riverine receiving waters. It is concluded that this systematic approach provides a comprehensive assessment of chemical fate, revealing the broad characteristics of chemical behavior and quantifying the likely local and regional exposure levels.
Predicting the toxicity of metal-spiked laboratory sediments using acid-volatile sulfide and interstitial water normalizations
Authors: Berry W.J. , Hansen D.J. , Boothman W.S. , Mahony J.D. , Robson D.L. , Di Toro D.M. , Shipley B.P. , Rogers B. , Corbin J.M. 
Published: March 2010

AbstractNumerous studies have shown that dry weight concentrations of metals in sediments cannot be used to predict toxicity across sediments. However, several studies using sediments from both freshwater and saltwater have shown that interstitial water concentration or normalizations involving acid-volatile sulfide (AVS) can be used to predict toxicity in sediments contaminated with cadmium, copper, nickel, lead, or zinc across a wide range of sediment types. Six separate experiments were conducted in which two or three sediments of varying AVS concentration were spiked with a series of concentrations of cadmium, copper, lead, nickel, or zinc or a mixture of four of these metals. The amphipod Ampelisca abdita was then exposed to the sediments in 10-d toxicity tests. Amphipod mortality was sediment dependent when plotted against dry weight metals concentration but was not sediment dependent when plotted against simultaneously extracted metal (SEM)/AVS or interstitial water toxic units (IWTUs). Sediments with SEM/AVS ratios &lt;1.0 were seldom (2.3%) toxic (i.e., caused &lt;24% mortality), while sediments with SEM/AVS ratios &gt;1.0 were frequently (80%) toxic. Similarly, sediments with &lt;0.5 IWTU were seldom toxic (3.0%), while sediments with &gt;0.5 IWTU were toxic 94.4% of the time. These results, coupled with results from related studies, demonstrate that an understanding of the fundamental chemical reactions which control the availability of cadmium, copper, lead, nickel, and zinc in sediments can be used to explain observed biological responses. We believe that using SEM/AVS ratios and IWTUs allows for more accurate predictions of acute mortality, with better causal linkage to metal concentration, than is possible with sediment evaluation tools which rely on dry weight metal concentrations.
Measurements of pesticide spray drift deposition into field boundaries and hedgerows: 2. Autumn applications
Authors: Longley Martin , Sotherton Nicolas W 
Published: March 2010

Abstract
Tractor spray applications of a pyrethroid insecticide combined with a fluorescent tracer were applied to cereal field edges on four separate occasions in the autumn. Spray drift measurements were made in field boundaries adjacent to conventionally sprayed and 6-m-wide unsprayed “Conservation Headlands,” which act as buffer zones designed to keep the outermost edge of the crop unsprayed with certain pesticide groups. The volume of drifting spray reaching field boundaries was dependent upon wind conditions and was significantly reduced by the use of these buffer zones. Comparisons of spray drift are made with comparable experiments carried out in summer cereals (reported in an accompanying paper). In a separate experiment, high mortalities of Spodoptera littoralis Boisd. larvae were recorded when they were exposed to grasses collected from hedge bottoms adjacent to conventionally sprayed headlands, and from additional spray applications made with a hand-held sprayer (used to simulate the levels of drift recorded in field trials). Larval mortalities were reduced, but still detectable, when grasses contaminated with drift adjacent to Conservation Headlands were bioassayed. In light of these findings, the current recommendation of these 6-m-wide buffer zones in cereals is discussed.
Calcium fluxes in juvenile tilapia, Oreochromis mossambicus, exposed to sublethal waterborne Cd, Cu or mixtures of these metals
Authors: Pelgrom Sylvia M G J , Lock Robert A C , Balm Paul H M , Bonga Sjoerd E Wendelaar 
Published: March 2010

Abstract
In juvenile tilapia the effects of waterborne Cu, Cd, and combinations of these metals on whole-body Ca fluxes were studied, using 45Ca as tracer. The maintenance of Ca homeostasis in fish is crucial throughout life but is especially important in young fish; Ca is also critical for growth. Single metal exposure had no effect on Ca fluxes after 6 d of exposure. In fish coexposed to 200 μg Cu L−1 + 70 μg Cd L−1 however, Ca influx was significantly decreased, whereas Ca efflux was not affected. As a result, the net flux was decreased. Because the effect on Ca fluxes observed in Cu/Cd-coexposed fish could not have been predicted from the effects of single metal exposures, this study underscores the impact of interactions between toxicants. Because natural freshwaters are commonly polluted by mixtures of metals, interactions between toxicants are important in risk assessment of heavy metals.
Toxic potencies of extracts of sediment and settling particulate matter collected in the recipient of a bleached pulp mill effluent before and after abandoning chlorine bleaching
Authors: Engwall Magnus , Broman Dag , Dencker Lennart , Näf Carina , Zebühr Yngve , Brunström Björn 
Published: March 2010

Abstract
Extracts of bottom sediment and settling particulate matter (SPM) samples collected in the recipient water body of a bleached pulp mill effluent were separated into three fractions: monoaromatic/aliphatic compounds, diaromatic compounds (e.g., polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans), and polyaromatic compounds (e.g., polycyclic aromatic hydrocarbons [PAHs]). The fractions were then tested for dioxinlike potency. The methods used for the assessment of dioxinlike potency were an in vitro assay, based on the induction of 7-ethoxyresorufin-O-deethylase (EROD) in chicken embryo livers, a test for EROD induction in ovo using chicken embryos, and an immunotoxicity test measuring inhibition of lymphoid cell development in cultured fetal mouse thymuses. The samples collected closest to the mill were the most potent. There was a time-dependent decrease in dioxinlike potency in the SPM samples collected near the mill, which coincided with the cessation of chlorine gas bleaching at the mill. The bioassays in general, and the in vitro chicken embryo liver bioassay in particular, proved useful in the assessment of dioxinlike compounds in the sediment and SPM samples. The polyaromatic fractions of the samples were generally more potent than the diaromatic fractions. Only a small part of the effects caused by the polyaromatic fractions could be explained by 15 analyzed PAHs, indicating the presence of unquantified polyaromatic compounds with dioxinlike effects. This investigation indicates that the cessation of chlorine bleaching in the pulp mill resulted in a reduced load of diaromatic dioxinlike compounds in the recipient water body.
Effects of embryonic and adult exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on hepatic microsomal testosterone hydroxylase activities in great blue herons (Ardea herodias)
Authors: Sanderson J Thomas , Janz David M , Bellward Gail D , Giesy John P 
Published: March 2010

AbstractIn a continuing effort to evaluate biomarkers of exposure of great blue herons (Ardea herodias) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons, we examined the effect of TCDD on hepatic microsomal testosterone hydroxylase activities. Heron embryos were exposed in ovo to 2 μg TCDD/kg egg (or corn oil vehicle) and sacrificed at hatch or 7 d posthatch. Adult herons were exposed intraperitoneally to 20 μg TCDD/kg and sacrificed 2 weeks later. The sex of the birds was known for the adults only. Hepatic microsomes of herons of each age group were able to hydroxylate testosterone at the 2β, 6β, 15α, 16α, or 16β positions. In 7-d-old chicks, an additional unidentified compound was formed. The age of the untreated herons had a strong influence on the activities of the five hydroxylases, with changes of up to 17-fold. The TCDD significantly (p &lt; 0.05) induced 2β-, 6β-, and 15α-testosterone hydroxylase activities in the adult females, 15α- in the adult males, and 6β-testosterone hydroxylase activity in the hatchlings. In the 7-d-old chicks, induction was no longer apparent. A significant correlation existed between hepatic microsomal ethoxyresorufin O-deethylase (EROD) and 6β-testosterone hydroxylase activity in hatchlings (r = 0.91; n = 12) and adult female herons (r = 1.0; n = 4). The TCDD-induced changes in testosterone hydroxylase activities occurred at doses that resulted in tissue concentrations and levels of EROD induction that were environmentally relevant, but did not result in overt toxicities.
Inability of bacteria to degrade low concentrations of toluene in water
Authors: Roch François , Alexander Martin 
Published: March 2010

Abstract
Microbial utilization of low concentrations of toluene in water was investigated. When bacteria that were not actively degrading toluene were incubated in solutions containing 2.1 to 11 μg of toluene/L, the concentrations remaining in solution after 8 d ranged from 0.69 to 0.99 μg/L. However, when the initial concentration was ≥31 μg/L, the concentration remaining was &lt;0.2 μg/L. When bacteria actively degrading toluene were inoculated into solutions containing 0.9 μg of toluene/L, the concentration remaining after 8 d was 79 ng/L. We propose that the inability of some bacteria to maintain or attain high metabolic activity on a compound present at low concentrations may prevent its rapid degradation in natural environments.
Effects of triphenyltin and pH on the growth and development ofRana lessonaeandRana esculentatadpoles
Authors: Fioramonti Ennio , Semlitsch Raymond D , Reyer Heinz-Ulrich , Fent Karl 
Published: March 2010

AbstractWe tested the s sceptibility of parental (Rana lessonae) and hemiclonal hybrid tadpoles of the R. esculenta complex to triphenyltin (TPT), a fungicide commonly used in agriculture, at renewed concentrations of 0.11, 0.81, and 1.87 μg/L over the entire larval period. Because habitats of R. lessonae are often characterized by a low pH and disturbed habitats such as gravel pits by high pH, we also tested whether pH 6.4 or pH 8.1 modifies their susceptibility to triphenyltin. We measured survival to metamorphosis, body mass at day 30, body mass at metamorphosis, and time to metamorphosis of individually reared tadpoles. Crosses of R. lessonae males with R. lessonae females and with two hemiclones of R. esculenta females produced tadpoles of R. lessonae, R. esculenta (GUT1) and R. esculenta (GUT2). At increasing triphenyltin concentrations, survival and growth rate decreased and time to metamorphosis increased. The GUT1 larvae of R. esculenta were the least and larvae of R. lessonae the most sensitive. The GUT2 larvae of R. esculenta were intermediate in sensitivity. The effect of pH also depended on the genotype. Tadpoles of R. lessonae had a higher growth rate and a shorter larval period at pH 6.4. The pH effect on tadpoles of R. esculenta was slight, but growth rate was lower and larval period longer at pH 6.4. Because TPT most strongly affected the larval period, exposure to TPT could decrease survival in natural ponds because of the increased risk of predation in permanent ponds or desiccation in drying ponds as well as the increased risk of additional chemical exposure. Our results indicate that the sexual parental species R. lessonae is more sensitive to environmental chemicals such as triphenyltin than is the hemiclonal hybrid R. esculenta.
Depuration and uptake kinetics of I, Cs, Mn, Zn and Cd by the earthworm (Lumbricus terrestris) in radiotracer-spiked litter
Authors: Sheppard Steve C , Evenden William G , Cornwell Teresa C 
Published: March 2010

AbstractThe relative depuration and uptake kinetics of contaminants should be known to interpret appropriately the use of organisms such as earthworms in environmental bioassays and monitoring. For example, 14-d earthworm bioassays should be interpreted with the knowledge that some contaminants will continue to accumulate in tissues for months. The radiotracers 125I, 134Cs, 54Mn, 65Zn, and 109Cd were applied to deciduous litter and specimens of Lumbricus terrestris were exposed, either to litter alone or to litter on the top of soil columns. Depuration was monitored for 120 d and uptake, in a separate experiment, for 20 d. Both depuration and uptake were described using two-phase, first-order statistical models. Gut clearance had a mean half-time of 1.4 d. The mean half-time for physiological depuration decreased from I (210 d) &gt; Cd (150 d) &gt; Zn (69 d) &gt; Mn (40 d) &gt; Cs (24 d). Both the depuration and the uptake experiments were necessary to resolve even partially the multiphase processes. Earthworm/soil dry weight concentration ratios decreased from Cd &gt; Zn &gt; I ≥ Cs ≥ Mn. The very slow kinetics indicate that tissue concentrations will increase continuously for a long time, with important implications for subsequent food-chain transfers.
A modeling framework for exploring the population-level effects of endocrine disruptors
Authors: McTavish Kathleen , Stech Harlan , Stay Frank 
Published: March 2010

AbstractMethods are proposed for modeling the population-level effects of endocrine-disrupting chemicals on age-structured populations. We present a framework for representing xenobiotic-induced impacts to reproductive, life-stage transition, and mortality rates. Numerical simulations are described addressing delayed disturbance and recovery dynamics and potential transgenerational effects.
Effects of waterborne mercury on terrestrial wildlife at clear lake: Evaluation and testing of a predictive model
Authors: Wolfe Marti , Norman Donald 
Published: March 2010

Abstract
Birds and mammals exposed to waterborne mercury (Hg) and methylmercury (MeHg) were collected and/or sampled at Clear Lake, California, USA, to field test the predictive wildlife criteria model developed for the Great Lakes Water Quality Initiative (GLWQI). Tissue samples collected from sampled animals were analyzed for Hg and organochlorine residues, and for selected physiologic parameters known to be affected by Hg. All mammalian organ tissues analyzed contained less than 12 ppm total Hg, wet weight. All avian tissue samples analyzed contained less than 3 ppm total Hg, wet weight. No evidence of Hg-associated health effects was found. Tissue Hg residues were compared with water, sediment, and animal food samples to characterize bioaccumulation of mercury in the Clear Lake food web. Total Hg bioaccumulation factors for the Clear Lake site closest to the Hg source were: TL-2: 11,100; TL-3: 31,200; TL-4, 190,000. Our results support the final wildlife criterion (1,300 pg/L) and suggest that the GLWQI model, with site-specific modifications, is predictive for other Hg-bearing aquatic systems.
Effect of nitrate-based bioremediation on contaminant distribution and sediment toxicity—column study
Authors: Hutchins Stephen R , Bantle John A , Schrock Elizabeth J 
Published: March 2010

Abstract
A laboratory column study was set up to evaluate changes in contaminant distribution and sediment toxicity following nitrate-based bioremediation and to correlate toxicity reduction with loss of fuel components. Glass columns were packed with sediment from an aquifer that had been contaminated with JP-4 jet fuel and were remediated using feed solution containing 20 mg/L NO3-N. Column influents and effluents were monitored for BTEXTMB (benzene, toluene, ethylbenzene, xylenes, trimethyl-benzenes), electron acceptors, nutrients, and dissolved gases. Duplicate columns were sacrificed after 1, 4, and 7 months, and core material was analyzed for chemical constituents. In addition, core material was evaluated for toxicity using FETAX, a developmental toxicity test employing frog embryos. After 1 month of operation, total mass of BTEXTMB dropped from 51.8 ± 7.3 mg to 29.8 ± 2.9 mg (42% reduction) in the column sediments, with 1.45 ± 0.06 mg eluting in the column effluents and 20.6 ± 3.0 mg being unaccountable, presumably due to biodegradation. Based on stoichiometry of denitrification, nitrate consumption and nitrite and nitrous oxide production were sufficient to account for the observed loss. In contrast, JP-4 levels only dropped from 2,070 ± 260 mg to 1,750 ± 22 mg (15% reduction). Despite the similar distribution of contaminants in the two columns of this first column pair, FETAX mortality remained unchanged at 93.3% in the first column and dropped from 93.3% to 11.7% in the second. Toxicity reduction could not be therefore directly attributed to either BTEXTMB or JP-4 levels. After 7 months, total mass reductions were 93.1 ± 1.1% and 35 ± 1.6% for BTEXTMB and JP-4, respectively, and FETAX mortality and malformation had declined to less than 10%. These data show that closure standards requiring complete removal of residual hydrocarbon may overestimate the time required to counteract sediment toxicity, and that nitrate-based bioremediation may be a viable treatment alternative for fuel-contaminated aquifers.
Ion-pair association of substituted phenolates with K+ in octanol
Authors: Strathmann Timothy J , Jafvert Chad T 
Published: March 2010

Abstract
The speciation, environmental distribution, and ultimate fate of phenolic compounds, a class of hydrophobic ionizable organic compounds, is influenced by both their hydrophobic and electrostatic characteristics. In this study, electrical conductance measurements were employed to characterize the ion-pair association properties of a monovalent inorganic cation (K+) with substituted phenolate anions in the model hydrophobic solvent, 1-octanol. Quantification of such processes is important for characterizing the overall partitioning to and speciation in octanol of phenolic compounds. Data were analyzed and association constants were calculated using a modified form of the Fuoss–Onsager equation for electrical conductivity. Results indicate that the magnitude of ion-pair association correlates with the electron-donating and -withdrawing characteristics of phenolic ring substituents. A quantitative structure–activity relationship was developed correlating ion-pair association constants to the sum of Hammett substituent constants for each species. The data suggest that for some phenolate salts, charged triple ion or higher aggregate formation may occur at elevated concentrations. A qualitative interpretation of this phenomenon and the selectivity of its occurrence are discussed.
Effects of application rate on avian risk from granular pesticides
Authors: Stafford Tamara R , Best Louis B 
Published: March 2010

Abstract
Fensulfothion was formulated on silica granules to evaluate the relationship between avian risk of adverse effects from granular pesticides and granule availability. Captive house sparrows (Passer domesticus) were offered the granular pesticide in bands on soil surfaces at application rates of 50, 100, 200, 400, 800, 1,200, 1,600, or 2,000 LD50/ft2. Individual pesticide granules were formulated with ½ the LD50 for house sparrows (0.3 mg/kg). Bird behavior, survival, and brain cholinesterase activity were used to assess pesticide exposure. A significant negative correlation between brain ChE activity and the natural logarithm of application rate indicated that the relationship between avian risk and granule availability was asymptotic rather than linear. Thus, the assumption, implicit in the LD50/ft2 risk index, that the potential exposure of birds to granular pesticides increases as granule availability increases may result in overestimates of risk to birds from granular pesticides, particularly at higher granule application rates.
Molecular orbital calculations to describe microbial reductive dechlorination of polychlorinated dioxins
Authors: Lynam Mary M , Kuty Michal , Damborsky Jiri , Koca Jaroslav , Adriaens Peter 
Published: March 2010

Abstract
Ab initio restricted Hartree Fock and density functional theory (DFT), as well as semiempirical Austin model 1 and parametrization method 3 molecular orbital calculations were carried out for a range of chlorinated dioxin molecules to obtain molecular descriptors such as HOMO–LUMO gaps (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) and partial atomic charges. The HOMO–LUMO gap is an indicator of stability in a molecule: the larger the gap the greater the stability of the molecule toward further reaction. These calculations indicate that with increasing extent of chlorination, the gap decreases. The observed charge pattern shows that carbon atoms in the peri (1,4,6,9) ring positions have a partial negative charge while those in the lateral (2,3,7,8) position have a partial positive or small partial negative charge. The descriptors, from the more precise DFT method, were used to rationalize experimental observations of dechlorination of dioxins. Reductive dechlorination pathways from two different experimental studies were examined using partial charges and estimated Gibbs free energy of dechlorination. In both experimental studies, highly thermodynamically favorable and less thermodynamically favorable pathways were observed. For a given chlorinated dioxin, when more than one degradation pathway was possible, dechlorination in the most thermodynamically favored pathway occurred at the most positively charged carbon atom in the ring, which was usually a lateral carbon atom. These results are discussed in light of a possible mechanism for reductive dechlorination.