bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of an onsite wastewater treatment system in sandy soil: Site characterization and fate of anionic and nonionic surfactants
Authors: Nielsen Allen M. , Decarvalho Alvaro J. , McAvoy Drew C. , Kravetz Lou , Cano Manuel L. , Anderson Damann L.
Published: March 2010

This study reports on the fate of linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and alcohol ether sulfate (AES) surfactants in a home septic system near Jacksonville (FL, USA) that has been used since 1976. The drainfield at this site resides in fine sand (<6% silt and clay) with an unsaturated zone that ranges from 0 to 1.3 m. During the wettest times of the year, it is likely that effluent from the septic system passes directly into the groundwater without exposure to an unsaturated zone of soil. Groundwater was collected during two sampling events, representing seasonal high and low groundwater table levels, and analyzed for the surfactants LAS, AES, and AE. During the wet season, the unsaturated zone was approximately 0.01 m beneath the drainfield. During the dry season, the unsaturated zone was about 0.4 m below the drainfield. Alcohol ethoxylate was not detected in any groundwater samples during either sampling. Alcohol ether sulfate was not found in the dry season sampling, but traces of AES had migrated downgradient about 4.7 m horizontally and 1.8 m vertically in the wet season. Linear alkylbenzene sulfonate was detected in some dry season samples and had moved downgradient some 11.7 m horizontally and 3.7 m vertically in the wet season. These observations demonstrate that these surfactants were removed to a great extent; otherwise, they would have traveled more than 260 m downgradient, which is the calculated distance that a conservative tracer like bromide would have moved downgradient over the life of the system. The most likely removal mechanisms for these surfactants were biodegradation and sorption. Therefore, this study indicates that LAS, AE, and AES are readily removed from groundwater in soils below septic system drainfields even in situations with minimal unsaturated soil zones.
Effect-directed fractionation and identification of cytochrome P4501A-inducing halogenated aromatic hydrocarbons in a contaminated sediment
Authors: Brack Werner , Schirmer Kristin , Kind Tobias , Schrader Steefi , Schüürmann Gerrit
Published: March 2010

On the basis of a new fractionation method combined with in vitro ethoxyresorufin-O-deethylase (EROD) induction in a rainbow trout liver cell line (RTL-W1) and chemical analysis, halogenated aromatic hydrocarbons with dioxin-like activity were identified in a sediment extract from Bitterfeld, Germany. The fractionation method allowed a separation of different nonplanar and coplanar polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) with different degrees of chlorination. The dioxin-like activity at the investigated site could be quantitatively assigned to PCDD/Fs. Both PCBs and PCNs could be excluded as the cause of the measured effects on the basis of the fractionation procedure and bioanalytical results. Thus, the method allowed the chemical analysis to focus on PCDD/Fs, with significant reduction of the analytical expense. The EROD-induction potency of sediment-extract fractions was quantified, and toxicants were confirmed by the application of induction equivalent quantities on the basis of fixed-effect-level concentrations that exhibit 15% of the maximum induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin. This approach was designed to minimize methodological limitations due to superimposing inhibitory effects.
Probabilistic risk assessment of reproductive effects of polychlorinated biphenyls on bottlenose dolphins (Tursiops truncatus) from the Southeast United States coast
Authors: Schwacke Lori H. , Voit Eberhard O. , Hansen Larry J. , Wells Randall S. , Mitchum Greg B. , Hohn Aleta A. , Fair Patricia A.
Published: March 2010

High levels of polychlorinated biphenyls (PCBs) have been reported in the tissues of some species of marine mammals. The high concentrations are of concern because a growing body of experimental evidence links PCBs to deleterious effects on reproduction, endocrine homeostasis, and immune system function. Much of the recent research has focused on determining the exposure of marine mammal populations to PCBs, but very little effort has been devoted to the actual risk assessments that are needed to determine the expected impacts of the documented exposures. We describe a novel risk assessment approach that integrates measured tissue concentrations of PCBs with a surrogate dose-response relationship and leads to predictions of health risks for marine mammals as well as to the uncertainties associated with these predictions. Specifically, we use PCB tissue residue data from three populations of bottlenose dolphins (Tursiops truncatus), study the feasibility of published dose-response data from a surrogate species, and combine this information to estimate the risk of detrimental reproductive effects in female dolphins. Our risk analyses for dolphin populations near Beaufort (NC, USA), Sarasota (FL, USA), and Matagorda Bay (TX, USA) indicate a high likelihood that reproductive success, primarily in primiparous females, is being severely impaired by chronic exposure to PCBs. Excess risk of reproductive failure, measured in terms of stillbirth or neonatal mortality, for primiparous females was estimated as 60% (Beaufort), 79% (Sarasota), and 78% (Matagorda Bay). Females of higher parity, which have previously off-loaded a majority of their PCB burden, exhibit a much lower risk.
The effect of aging on pyrene transformation in sediments
Authors: Guthrie-Nichols Elizabeth , Grasham Adam , Kazunga Chikoma , Sangaiah Ramiah , Gold Avram , Bortiatynski Jacqueline , Salloum Myrna , Hatcher Patrick
Published: March 2010

The effect of aging on pyrene transformation and pyrene association with fractions of the sedimentary organic matrix (SdOM) was evaluated using [4,9-13C2]pyrene. Sediments were collected from a site of previous petroleum hydrocarbon contamination (New Orleans, LA, USA). Aged sediments were autoclaved for 1 h, amended with pyrene, and then stored in the dark in a 0.05% NaN3 solution for 120 d. Both aged and nonaged sediments were incubated in aerated microcosms for 120 d. Microcosms were acidified to collect evolved carbon dioxide (CO2); sediments were fractionated and lipid extracted to quantify pyrene in SdOM fractions. Cross-polarization magic angle spinning 13C-nuclear magnetic resonance (CPMAS 13C-NMR) spectra indicated that synthetic aging techniques did alter SdOM structure to some degree, but these changes did not affect SdOM affinity for pyrene. Aging delayed pyrene mineralization and increased pyrene concentrations extracted from bulk sediment and humic fractions. Aging also reduced the toxicity of sediment humin. Pyrene-4,5-dione and pyrene cis-4,5-dihydrodiol were identified in extracts of aged sediments by 13C-NMR and gas chromatography mass spectrometry, respectively.
The fate, distribution, and toxicity of lindane in tests withChironomus riparius: Effects of bioturbation and sediment organic matter content
Authors: Goedkoop Willem , Peterson Märit
Published: March 2010

In this laboratory study, we address the effect of Chironomus bioturbation (0, 2,000, 6,000, and 18,000 ind/m2) and sediment organic matter content (10, 20, and 40%) on the fate, distribution, and bioavailability of 14C-lindane under standardized conditions in toxicity tests with artificial sediment. The results show that both Chironomus burrowing activity and sediment organic matter strongly modify test conditions. Larval mortality and development were inversely related with Chironomus densities and lindane concentration. Sediment organic matter content affected larval development rates but not mortality. Partitioning of lindane between the sediment, overlying water, and interstitial water was affected negatively by Chironomus larval densities; however, sediment partitioning was positively affected by sediment organic matter content. Bioturbation by Chironomus resulted in a remobilization of particle-associated lindane to the interstitial and overlying water, implying an increase in the bioavailability of the test compound. Strong positive relationships were found between Chironomus densities and lindane concentrations in interstitial water. The presence of Chironomus also resulted in lower label recovery. Label recovery on sediment particles ranged from 49 to 61% of initially added label in microcosms without Chironomus, from 41 to 56% at low larval densities, and from 15 to 50% at high larval densities. These results show that large discrepancies may exist between nominal test concentrations (from test compound additions) and true exposure concentrations even under standardized test conditions, which can introduce a relatively large error term in risk assessments. Calculations show that volatilization may be a quantitatively important sink for test compounds.
Oxidative stress biomarkers in bivalves transplanted to the Guadalquivir estuary after Aznalcóllar spill
Authors: Romero-Ruiz Antonio , Amezcua Oscar , Rodríguez-Ortega Manuel J. , Muñoz José L. , Alhama José , Rodríguez-Ariza Antonio , Gómez-Ariza José L. , López-Barea Juan
Published: March 2010

Biological effects of metals were studied in clams (Scrobicularia plana) transplanted to Guadalquivir estuary (Spain) at several times after the spill of toxic metals from Aznalcóllar pyrite mine (southwest Spain) (April 1998) using biochemical biomarkers responsive to reactive oxygen species. Significant As, Cd, Fe, Mn, Ni, and Pb uptake was found in clams living for seven months at the estuary (from July 1999). Increased activity of antioxidant (catalase, glucose-6-phosphate, and 6-phosphogluconate dehydrogenase) and glutathione-related (glutathione reductase and glyoxalase I and II) enzymes was also found after short exposures; the levels of malondialdehyde and metallothionein increased also, particularly with long exposures. Clams living four weeks at the estuary (from March 2000) but not at a reference site also accumulated metals. The higher malondialdehyde and lower reduced-glutathione levels and the more oxidized glutathione status confirmed the oxidative stress of clams living at the estuary, while no marked increase of antioxidant activities was found this time. Lower metal availability along the second transplant could explain the limited responses in this shorter experiment. Although the status of Guadalquivir estuary has recovered since Aznalcóllar spill, continuous monitoring is needed to confirm its progress and to be alert to possible deterioration after heavy rains.
The bioconcentration and metabolism of chlorpyrifos by the eastern oyster,Crassostrea virginica
Authors: Woodburn Kent B. , Hansen Steven C. , Roth Gary A. , Strauss Kathryn
Published: March 2010

Eastern oysters (Crassostrea virginica) were exposed to [14C]chlorpyrifos (O,O-diethyl-O-[3,5,6-trichloro-2-pyridyl] phosphorothioate) at an average measured seawater concentration of 0.6 μg/L under flow-through conditions for 28 d. The compound O,O-diethyl-O-(3,5-dichloro-6-methylthio-2-pyridyl)phosphorothioate (DMP) was extracted and identified as the single metabolite observed, and this metabolite constituted the majority of the total [14C] activity in the oyster at all sampling times. Once oysters were exposed to clean water, both chlorpyrifos and DMP residues cleared rapidly from whole oysters, with elimination half-lives of <3 d. A simple two-compartment uptake/elimination model was adequate to describe total [14C] activity in whole oysters, edible tissue, and oyster liquor. The average bioconcentration factors (BCFs) for total [14C] activity in whole oysters, edible tissue, and oyster liquor were 565, 1,400, and 35 ml/g, respectively. The parent [14C]chlorpyrifos accumulated to a peak residue concentration of 135 μg/kg in whole oyster tissue, representing an empirical [14C]chlorpyrifos BCF value in the oyster of approximately 225 ml/g; the BCF value for [14C]chlorpyrifos was lower than the BCF for total [14C] activity in whole oysters and edible tissue because of extensive metabolism to DMP and oyster elimination processes.
Immunocompetence of juvenile Chinook salmon against Listonella anguillarum following dietary exposure to Aroclor® 1254
Authors: Powell David B. , Palm Roger C. , Skillman Ann , Godtfredsen Kathy
Published: March 2010

Controlled laboratory challenges with pathogenic Listonella (formerly Vibrio) anguillarum bacteria were used to examine potential effects of dietary exposure to polychlorinated biphenyls (PCBs) on the growth and immunocompetence of juvenile Puget Sound (WA, USA) Chinook salmon (Oncorhynchus tschawytscha). Salmon were fed four levels of the PCB congener mixture Aroclor® 1254 for 28 d to bracket likely exposure to PCBs in the lower Duwamish waterway near Seattle, Washington, USA. Fish were transferred to five replicate tanks per dose, exposed to L. anguillarum, and monitored for 14 d. Half the PCB-dosed fish were vaccinated against L. anguillarum, and specific immunity was allowed to develop in this group for three weeks prior to challenge. All mortalities following challenge were individually sampled for bacteria to identify the cause of death. The data indicate that dietary PCB exposure, even at relatively high levels, did not have a significant effect on growth, innate disease resistance, or acquired immunity to L. anguillarum. The controlled laboratory experiments in this study suggest that the immune system of Chinook salmon is not sensitive to orally delivered PCBs at environmentally relevant concentrations.
Joint acute toxicity of esfenvalerate and diazinon to larval fathead minnows (Pimephales promelas)
Authors: Denton Debra L. , Wheelock Craig E. , Murray Shauna A. , Deanovic Linda A. , Hammock Bruce D. , Hinton David E.
Published: March 2010

California (USA) agriculture employs pyrethroid and organophosphate insecticides to control insects in orchards and other crops. Diazinon and esfenvalerate were selected for this study because of their application overlaps. Toxicological and biochemical responses of larval fathead minnows (Pimephales promelas) exposed singly and in combinations to esfenvalerate and diazinon were determined. Exposures were 96-h static renewal tests that used standard U.S. Environmental Protection Agency acute toxicity test methods. After pesticide exposures, larvae were evaluated for carboxylesterase and acetylcholinesterase activity, and histopathological effects. Carboxylesterase activity was examined because of its potential influence on the toxicity of both organophosphates and pyrethroids. In vivo studies demonstrated that diazinon significantly inhibited carboxylesterase activity at nominal water concentrations as low as 50 μg/L. However, esfenvalerate did not affect carboxylesterase activity at any concentration tested. Liver glycogen depletion was the only histopathological effect observed; this effect was demonstrated with the individual pesticides and pesticide combinations (i.e., mixtures). The combinations of diazinon and esfenvalerate causing acute toxicity to fathead minnow larvae appeared to be greater than additive (i.e., synergistic) in all three tests.
Environmental exposure to polychlorinated biphenyls among raccoons (Procyon lotor) at the Paducah Gaseous Diffusion Plant, Western Kentucky, USA
Authors: Smith Philip N. , Johnson Kevin A. , Anderson Todd A. , McMurry Scott T.
Published: March 2010

An investigation involving raccoons (Procyon lotor) as a sentinel species at the Paducah Gaseous Diffusion Plant (PGDP) in Western Kentucky (USA) delineated the extent of exposure to polychlorinated biphenyls (PCBs) and PCB spatial distribution. Raccoon exposure to PCBs was demonstrated through analysis of subcutaneous fat, abdominal fat, liver, and brain tissues from raccoons collected at the PGDP but also was clearly evident in raccoons from a reference area situated along the Ohio River (USA). Raccoons with the highest tissue PCB concentrations appeared to be those inhabiting areas nearest the plant itself and most likely those that ventured into the plants interior. Male raccoons at the PGDP had similar concentrations of total PCBs in subcutaneous fat (1.86 ± 0.64 μg/g) as males from the reference site (1.41 ± 0.35 μg/g), but females had higher PCB body burdens than those at the reference site (9.90 ± 6.13 μg/g vs 0.75 ± 0.40 μg/g). Gross measurements of exposure to radiation-producing materials revealed that counts per minute exceeded background in 61% of PGDP raccoons compared with 27% at the reference site and five raccoons at the PGDP had beta counts that were more than twice the background. Differences among trapping success, growth rates, and serum chemistry parameters were noted but may have been related to habitat and other environmental and population density factors.
Spatial variation of metals and acid volatile sulfide in floodplain lake sediment
Authors: van Griethuysena Corine , Meijboom Erwin W. , Koelmans Albert A.
Published: March 2010

In risk assessment of aquatic sediments, much attention is paid to the immobilizing effect of acid volatile sulfide (AVS) on trace metals. The difference of AVS and simultaneously extracted metals (SEM) gives an indication of metal availability. In floodplain sediments, where changing redox conditions occur. AVS may play a major role in determining variation in metal availability. The importance of spatial heterogeneity has been recognized in risk assessment of trace-metal-polluted sediments. However, little is known about spatial variation of available metal fractions. We studied spatial variability of sediment, environmental conditions, total contaminant concentrations, and available metals (as SEM-AVS or SEM-AVS/fOC) in a floodplain lake. The top 5 cm of sediment was sampled at 43 locations. Data were analyzed with correlation and principal component analysis as well as with geostatistical methods. Trace metal and SEM concentrations and most sediment characteristics were more or less constant within 10%. In contrast, AVS concentrations were much more variable and showed a strong spatial dependence due to differences in lake depth, total sulfur pools, and redox potential (Eh), which resulted in crucial differences in trace-metal availability within the lake. The spatial pattern of SEM-AVS deviates from total or normalized trace-metal patterns. This particularly has implications for risk assessment of sediments prone to dynamic hydrological conditions, where AVS concentrations are also variable in time.
The use of carbon thirteen nuclear magnetic resonance spectra to predict dioxin and furan binding affinities to the aryl hydrocarbon receptor
Authors: Shade Lindsay , Beger Richard D. , Wilkes Jon G.
Published: March 2010

Four spectroscopic data-activity relationship (SDAR) models for polychlorinated dibenzofurans (PCDFs) and dibenzodioxins (PCDDs) binding to the aryl hydrocarbon receptor (AhR) have been developed based on simulated 13C nuclear magnetic resonance (NMR) data. Models were developed using discriminant function analysis of the compounds' spectral data. An SDAR model with two classifications for 26 PCDF compounds had a leave-one-out (LOO) cross-validation accuracy of 89%. A two-classification SDAR model for 14 PCDD compounds had LOO cross-validation accuracy of 95%. A two-classification SDAR model combining 14 PCDD and 26 PCDF compounds had LOO cross-validation accuracy of 88%, while a four-classification SDAR model based on the same 14 PCDD and 26 PCDF compounds had LOO cross-validation accuracy of 92%. We used each appropriate SDAR model to classify 41 PCDD and/or 121 PCDF compounds with unknown binding affinities to the AhR. The SDAR models provide a rapid, simple, and valid way to model the PCDF and PCDD binding activity in relation to the AhR.
Anaerobic degradation of linear alkylbenzene sulfonate
Authors: Mogensen Anders S. , Haagensen Frank , Ahring Birgitte K.
Published: March 2010

Linear alkylbenzene sulfonate (LAS) found in wastewater is removed in the wastewater treatment facilities by sorption and aerobic biodegradation. The anaerobic digestion of sewage sludge has not been shown to contribute to the removal. The concentration of LAS based on dry matter typically increases during anaerobic stabilization due to transformation of easily degradable organic matter. Hence, LAS is regarded as resistant to biodegradation under anaerobic conditions. We present data from a lab-scale semi-continuously stirred tank reactor (CSTR) spiked with linear dodecylbenzene sulfonate (C12 LAS), which show that C12 LAS was biodegradable under methanogenic conditions. Sorption of C12 LAS on sewage sludge was described with a Freundlich isotherm. The C12 LAS sorption was determined with different concentrations of total solids (TS). In the semi-continuously stirred tank reactor, 18% of the added C12 LAS was bioavailable and 20% was biotransformed when spiking with 100 mg/L of C12 LAS and a TS concentration of 14.2 mg/L. Enhanced bioavailability of C12 LAS was obtained in an upflow anaerobic sludge blanket (UASB) reactor inoculated with granular sludge and sewage sludge. Biodegradation under thermophilic conditions was 37% with LAS as sole carbon source. Benzaldehyde was produced in the UASB reactor during LAS transformation.
Time course of metal loss inLumbriculus variegatusfollowing sediment exposure
Authors: Dawson Timothy D. , Lott Kevin G. , Leonard Edward N. , Mount David R.
Published: March 2010

After exposure for 21 d to sediment spiked with Cd, Pb, Cu, or Zn, oligochaetes (Lumbriculus variegatus) held in clean water depurated metal rapidly over the first few hours but much more slowly from 8 h up to 32 h. Results are consistent with previous work suggesting a 6-h depuration period as generally appropriate for sediment bioaccumulation studies with L. variegatus.
Changes in cellular energy budget as a measure of whole effluent toxicity in zebrafish (Danio rerio)
Authors: Smolders Roel , De Boeck Gudrun , Blust Ronny
Published: March 2010

Organisms exposed to suboptimal conditions face an a priori cost of combating stress in terms of metabolic resources. The energy available for maintenance, growth, and reproduction, based on the biochemical analysis of the energy budget rather than on the direct measurement of those endpoints, may therefore provide a sensitive measure of stress in an organism. The aim of this study was to validate changes in energy budget as an ecologically relevant sublethal parameter by comparing these responses with physiological, growth, and reproductive endpoints. A toxicity test with zebrafish (Danio rerio) was conducted where fish were exposed to a control and 50, 75, and 100% effluent for 28 d under flow-through conditions. Effects of effluent exposure were measured as changes in glycogen, lipid, and protein budgets. Furthermore, the observed effects were linked to different processes like growth, condition, respiration, and reproduction within the same populations. Our results indicate that changes in lipid budgets in exposed fish were the most sensitive endpoint. Excellent relations were found between cellular energy budgets, relative condition factor, and respiration (r2 = 0.795, p < 0.001; and r2 = 0.735, p < 0.001, respectively), but relations were poorer for reproductive output (r2 = 0.410, p < 0.034). As a whole, especially changes in lipid energy budgets provide a sensitive and fast indicator of altered condition in zebrafish under the given exposure regime and allow linking cellular effects to other endpoints within the same exposed populations.
Effects of ammonium perchlorate on the reproductive performance and thyroid follicle histology of zebrafish
Authors: Patiño Reynaldo , Wainscott Melody R. , Cruz-Li Emilia I. , Balakrishnan Saravanan , McMurry Cynthia , Blazer Vicki S. , Anderson Todd A.
Published: March 2010

Adult zebrafish were reared up to eight weeks in control water or in water containing ammonium perchlorate (AP) at measured perchlorate concentrations of 18 (environmentally relevant, high) and 677 ppm. Groups of eight females were paired with four males on a weekly basis to assess AP effects on spawned egg volume, an index of reproductive performance. All treatments were applied to four to five spawning replicates. At 677 ppm, spawn volume was reduced within one week and became negligible after four weeks. At 18 ppm, spawn volume was unaffected even after eight weeks. Also, perchlorate at 18 ppm did not affect percentage egg fertilization. Fish were collected at the end of the exposures (677 ppm, four weeks; control and 18 ppm, eight weeks) for whole-body perchlorate content and thyroid histopathological analysis. Fish perchlorate levels were about one-hundredth of those of treatment water levels, indicating that waterborne perchlorate does not accumulate in whole fish. At 677 ppm for four weeks, perchlorate caused thyroid follicle cell (nuclear) hypertrophy and angiogenesis, whereas at 18 ppm for eight weeks, its effects were more pronounced and included hypertrophy, angiogenesis, hyperplasia, and colloid depletion. In conclusion, an eight-week exposure of adult zebrafish to 18 ppm perchlorate (high environmentally relevant concentrations) affected the histological condition of their thyroid follicles but not their reproductive performance. The effect of 677 ppm perchlorate on reproduction may be due to extrathyroidal toxicity. Further research is needed to determine if AP at lower environmentally relevant concentrations also affects the thyroid follicles of zebrafish.
Copper-induced modifications of the trophic relations in riverine algal-bacterial biofilms
Authors: Barranguet Christiane , van den Ende Frank P. , Rutgers Michiel , Breure Anton M. , Greijdanus Marianne , Sinke Jan J. , Admiraal Wim
Published: March 2010

The effects of copper (Cu) on photosynthetic riverine biofilms were studied in artificial stream channels. Direct effects on the composition and functioning of the biofilms were investigated using plant pigments, community-level physiological profiles (CLPP), and pulse-amplitude-modulated (PAM) fluorescence. Copper caused a significant reduction of microalgal biomass and induced a shift in the population from diatoms to cyanobacteria. However, a decrease in biomass indicated that the replacement of species was not totally effective to counteract the toxic effects of Cu. A direct effect of Cu could also be shown in the bacterial community, and, furthermore, changes in the CLPP could be related to the Cu treatment. Copper-exposed biofilms lost the capacity to use between 11 and 15% of the substrates, but many of the remaining capacities became more robust, indicating an increased Cu tolerance due to the exposure. The change in the biofilm microbial composition points to the indirect effects of Cu on biofilms due to the close interdependence between biofilm autotrophic and heterotrophic compartments. Grazing by snails, which appeared to be an important factor structuring biofilms without any Cu addition, had a very minor effect on Cu-exposed biofilms. Although grazing changed the bacterial composition, its effects were not detected either on the algal community or on the biofilm community tolerance to Cu.
Mechanism of acute silver toxicity in Daphnia magna
Authors: Bianchini Adalto , Wood Chris M.
Published: March 2010

Daphnids (Daphnia magna) were exposed to AgNO3 at 0.303 ± 0.017 μg silver/L (46.9% as Ag+), in the absence of food, in moderately hard synthetic water under static conditions for up to 48 h. Results from accumulation experiments demonstrated that silver body burden was inversely related to body mass. Daphnids exposed to silver exhibited ionoregulatory disturbance, which was characterized by decreases in whole-body sodium concentration. This ionoregulatory disturbance was explained, at least in part, by a competitive inhibition of the whole-body sodium uptake (six- to sevenfold increase in the Michaelis constant with no change in maximal velocity), which was complete by 1 h of exposure, and resulted in approximately 40% inhibition of sodium influx from the water. A rapidly developing inhibition of whole-body Na+,K+-dependent adenosine triphosphatase (Na+,K+-ATPase) activity, significant by 2 h and complete at 90% blockade by 12 h, also was observed during exposure to AgNO3. Therefore, these findings clearly demonstrate that the key mechanism involved in acute Ag+ toxicity in D. magna, the most sensitive freshwater organism tested to date, resembles that described for freshwater fish— that is, inhibition of active sodium uptake by blockade of Na+,K+-ATPase. Furthermore, the results showed that Na+,K+-ATPase inhibition was directly related to silver accumulation in the whole body of D. magna. However, the nature of the sodium uptake inhibition (competitive vs noncompetitive in fish) and the fact that whole-body chloride concentration was not disturbed in daphnids was different from fish. With regard to the biotic ligand model (BLM) for silver, our results yielded a log K value of about 8.9. However, the current version of the BLM uses a rainbow trout log K value (7.3) but achieves the correct sensitivity of the model for daphnids by reducing the saturation of toxic sites needed to cause toxicity. An alternative way may be to use the log K value derived from the present results.
Susceptibility of black fly larvae (Diptera: Simuliidae) to lawn-care insecticides individually and as mixtures
Authors: Overmyer Jay P. , Armbrust Kevin L. , Noblet Ray
Published: March 2010

Urban and suburban watersheds have the potential to be highly impacted by chemicals, especially insecticides to control insect pests on lawns, ornamental plants, and home gardens. Three of the most common lawn-care insecticides detected in urban watersheds, carbaryl, chlorpyrifos, and malathion, have been evaluated using an acute orbital shaker toxicity test to determine their respective concentrations that produce 50% mortality (LC50) in Simulium vittatum Zetterstedt cytospecies IS-7 larvae. Results of the 48-h LC50 tests show chlorpyrifos to be the most toxic to black fly larvae (LC50 = 0.28 μg/L) followed by carbaryl (LC50 = 23.72 μg/L) and malathion (LC50 = 54.20 μg/L). These insecticides were also tested as binary and ternary mixtures using the toxic unit (TU) approach. Toxicity was shown to be greater than additive for the ternary mixture of chlorpyrifos—carbaryl—malathion (LC50 = 0.56 TU) and the binary mixtures of chlorpyrifos—malathion (LC50 = 0.72 TU) and carbaryl-malathion (LC50 = 0.78 TU). The binary combination of chlorpyrifos and carbaryl was shown to be additive (LC50 = 0.98 TU). These results indicate that aquatic invertebrate populations in urban and suburban streams may experience a higher-than-expected increase in toxicity-related effects when all three chemicals are present in the waterway.
Acute-to-chronic species sensitivity distribution extrapolation
Authors: Duboudin Cédric , Ciffroy Philippe , Magaud Hélène
Published: March 2010

Seeking to make greater use of available data for risk assessment of substances, we constructed, for the situation in which chronic data are limited or even nonexistent but acute data are relatively large, an acute to chronic transformation (ACT) methodology based on the concept of species sensitivity distributions (SSDs). This ACT methodology uses a comparison of acute and chronic SSDs, separately for vertebrate data (with 22 substances) and for invertebrate data (with 15 substances). Rather than comparing an acute toxicity value with a chronic value, as when calculating an acute to chronic ratio (ACR), samples of acute and chronic data corresponding to the same category of species were compared. Starting from a sample of acute data, the ACT methodology showed relationships that enable the creation of a sample of predicted chronic values. This sample can then be used to calculate a predicted chronic hazardous concentration potentially affecting 5% of species (HC5%), just as with a sample of real chronic toxicity values. This ACT approach was tested on 11 substances. For each substance, the real chronic HC5% and the predicted chronic HC5% were calculated and compared. The ratio between chronic HC5% and ACT HC5% was, on average, 1.6 and did not exceed 4.4 for the 11 substances studied.
Effects of egg order on organic and inorganic element concentrations and egg characteristics in tree swallows,Tachycineta bicolor
Authors: Custer Christine M. , Gray Brian R. , Custer Thomas W.
Published: March 2010

The laying order of tree swallow eggs was identified from the Housatonic River, Berkshire County, Massachusetts, USA, and eggs were chemically analyzed individually to document possible effects of laying order on organic contaminant and inorganic element concentrations. Effects of laying order on other parameters such as egg weight, size, and lipid and moisture content also were assessed. Some effects of egg order on total polychlorinated biphenyls (PCBs) were detected, but the effect was not uniform across individual females or between years. In 2004, clutches with higher total PCBs tended to have concentrations decline across egg order, whereas clutches with lower concentrations of PCBs tended to increase across egg order. In contrast, in 2005, there was a tendency for concentrations to increase across egg order. Polychlorinated biphenyl concentrations were highly variable within and among clutches in both years. The directionality of egg order associations (i.e., slopes) for trace elements was element dependent, was positive for Mn and Zn, was negative for B, and had no slope for Cr. Whole egg weight increased across egg order. Percentage lipid was variable within a clutch, with no pattern common across all females. Percentage lipid was also correlated with organic contaminant concentration. In highly contaminated environments, higher lipid content could have the unanticipated corollary of having higher concentrations of lipophilic contaminants such as PCBs. To reduce the effect of high variation within a clutch when assessing contamination exposure, it is recommended that two eggs per clutch be collected and pooled for chemical analysis. We further recommend that, as long as the two eggs are randomly collected, the additional effort needed to identify and collect specific eggs is not warranted. Environ. Toxicol. Chem. 2010;29:909–921. © 2009 SETAC
Mercury concentrations in landlocked Arctic char (Salvelinus alpinus) from the Canadian Arctic. Part II: Influence of lake biotic and abiotic characteristics on geographic trends in 27 populations
Authors: Gantner Nikolaus , Muir Derek C. , Power Michael , Iqaluk Deborah , Reist James D. , Babaluk John A. , Meili Markus , Borg Hans , Hammar Johan , Michaud Wendy , Dempson Brian , Solomon Keith R.
Published: March 2010

Among-lake variation in mercury (Hg) concentrations in landlocked Arctic char was examined in 27 char populations from remote lakes across the Canadian Arctic. A total of 520 landlocked Arctic char were collected from 27 lakes, as well as sediments and surface water from a subset of lakes in 1999, 2002, and 2005 to 2007. Size, length, age, and trophic position (δ15N) of individual char were determined and relationships with total Hg (THg) concentrations investigated, to identify a common covariate for adjustment using analysis of covariance (ANCOVA). A subset of 216 char from 24 populations was used for spatial comparison, after length-adjustment. The influence of trophic position and food web length and abiotic characteristics such as location, geomorphology, lake area, catchment area, catchment-to-lake area ratio of the lakes on adjusted THg concentrations in char muscle tissue were then evaluated. Arctic char from Amituk Lake (Cornwallis Island) had the highest Hg concentrations (1.31 µg/g wet wt), while Tessisoak Lake (Labrador, 0.07 µg/g wet wt) had the lowest. Concentrations of THg were positively correlated with size, δ15N, and age, respectively, in 88, 71, and 58% of 24 char populations. Length and δ15N were correlated in 67% of 24 char populations. Food chain length did not explain the differences in length-adjusted THg concentrations in char. No relationships between adjusted THg concentrations in char and latitude or longitude were found, however, THg concentrations in char showed a positive correlation with catchment-to-lake area ratio. Furthermore, we conclude that inputs from the surrounding environment may influence THg concentrations, and will ultimately affect THg concentrations in char as a result of predicted climate-driven changes that may occur in Arctic lake watersheds. Environ. Toxicol. Chem. 2010;29:633–643. © 2009 SETAC
A simple model to estimate monthly forest evapotranspiration in Japan from monthly temperature
Authors: Komatsu Hikaru , Kume Tomonori , Otsuki Kyoichi
Published: March 2010

The estimation of evapotranspiration (E) in forested areas is required for various practical purposes (e.g. evaluation of drought risks) in Japan. This study developed a model that estimates monthly forest E in Japan with the input of monthly temperature (T). The model is based on the assumptions that E equals the equilibrium evaporation rate (Eeq) and that Eeq is approximated by a function of T. The model formulates E as E (mm month−1) = 3·48 T ( °C) + 32·3. The accuracy of the model was examined using monthly E data derived using short‐term water balance (WB) and micrometeorological (M) methods for 15 forest sites in Japan. The model estimated monthly E more accurately than did the Thornthwaite and Hamon equations according to regression analysis of the estimated E and E derived using the WB and M methods. Although the model tended to overestimate monthly E, the overestimation could be reduced by considering the effect of precipitation on E. As T data are commonly available all over Japan, the model would be a useful tool to estimate forest E in Japan. Copyright © 2010 John Wiley & Sons, Ltd.
The temporal trends of reference evapotranspiration and its sensitivity to key meteorological variables in the Yellow River Basin, China
Authors: Liu Qiang , Yang Zhifeng , Cui Baoshan , Sun Tao
Published: March 2010

The temporal trends of reference evapotranspiration (ETref) reflect the combined effects of radiometric and aerodynamic variables, such as global solar radiation (Rs), wind speed, relative humidity and air temperature. The temporal trends of annual ETref during 1961–2006 calculated by Penman‐Monteith method were explored and the underlying causes for these trends were analysed in the Yellow River Basin (YRB). The contributions of key meteorological variables to the temporal trend of ETref were detected using the detrended method and then sensitivity coefficients of ETref to meteorological variables were determined. For ETref, positive trends in the upper, middle and whole of YRB, and significant negative trend (P = 0·05) in the lower basin were obtained by the linear fitted model. Significant increasing trend (P = 0·05) in air temperature and decreasing trend in relative humidity were the main causes for the increasing trends of ETref in the upper, middle and whole basins. For the whole basin, the increasing trend of ETref was mainly caused by the significant increase (P = 0·05) in air temperature and to a lesser extent by a decrease in the relative humidity, decreasing trends of Rs and wind speed reduced ETref. The spatial distribution of sensitivity coefficients addressed that the sensitive regions for ETref response to the changes of the four meteorological variables are different in the YRB. The sensitive region lay in the upper basin for Rs, the northwest portion of the middle basin for wind speed, the south portion of YRB for relative humidity and the west portion of the upper basin and the north portion of the middle basin for air temperature. In general, Rs was the most sensitive variable for ETref, followed by relative humidity, air temperature and wind speed in the basin scale. Copyright © 2010 John Wiley & Sons, Ltd.
Diversification of rural livelihood strategies and its effect on local landscape restoration in the semiarid hilly area of the Loess Plateau, China
Authors: Wang L. , Zhang J.‐L. , Liu L.‐M.
Published: March 2010

This study is about the diversification of livelihood strategies and the interaction of farmers' livelihood with landscape change in Zhongzhuang small watershed, Pengyang County in Ningxia Autonomous region located in the Loess Plateau, western China. Farmers' livelihoods and landscape patterns during 1978–2007 in Zhongzhuang were analysed. In different stages, diverse limiting factors were discovered behind the diversification process of livelihood strategies. Before 1978, ‘planned economy’, ‘production team organization’, strict ‘household registration system’ and the scarcity of livelihood assets were the main factors restricting the diversification of livelihood strategies. From 1978 to 1993, the reform and open policy provided opportunities for local people to diversify their livelihood strategies, but livelihood strategies based on crop production still took an important role in their life. From 2000 to 2007, national policies brought assistance to help local farmers diversify their agricultural activities. However, the insufficient and incomplete credit and insurance market and lack of skill were the main factors constraining non‐farm activity diversification. Meanwhile, through analysis of the links between livelihood strategies diversification and landscape pattern change, we found that diversification of farmers' livelihoods contributed to the recovery of the landscape. Finally, using this relationship, steps for future landscape restoration is proposed, which provide a new view of landscape restoration research in the Loess Plateau. Copyright © 2010 John Wiley & Sons, Ltd.
Adaptive styles in elite collegiate athletes: the role of activation and self‐regulation
Authors: Steiner Hans , Denny Katherine , Stemmle Pascale
Published: March 2010

The present study examined the interaction of emotional activation and self‐regulation in elite collegiate athletes. We hypothesized that athletes would report higher levels of self‐restraint, repressive defensiveness and denial of distress, but lower levels of distress than non‐athletes. Participants were composed of 461 collegiate athletes and 61 age‐ and gender‐matched non‐athletes from Stanford University. Social‐emotional adjustment and personality were assessed with the Weinberger Adjustment Inventory. Results indicate significant differences between athletes and non‐athletes. Athletes report lower levels of distress, higher levels of self‐restraint, repressive defensiveness and denial of distress. Logistic regressions assessed the important predictors of athlete status. Age, denial of distress and responsibility proved to be the most significant indicators of athlete status. Data can be interpreted in at least two ways: (1) athletes are better at dealing with pressure and therefore report lower levels of distress; or (2) athletes report lower distress because they utilize high levels of repressive defensiveness and denial of distress. Utilizing non self‐report methods would further clarify this question and would provide a deeper understanding of personality traits in athletes. Copyright © 2010 John Wiley & Sons, Ltd.
Psychosocial treatment refusal in personality disorder: a comparative study
Authors: Chiesa Marco , Martino Francesca , Pozzi Euro
Published: March 2010

There is a paucity of research concerning the identification of features implicated in treatment refusal by personality disorder. This study aims to identify clinical factors that may affect treatment uptake to a specialist psychosocial programme for personality disorder. Following a lengthy assessment, 39 patients (out of a total of 60 referrals) were offered entry to the programme. Fourteen patients who did not take up the offer of treatment and 25 patients who started the programme are compared on a number of demographic, diagnostic and clinical variables, including severity of presentation and subjective experience of the assessment process. The results show that, relative to non‐refusers, refusers were significantly younger, single, had a higher frequency of borderline personality disorder (BPD), experienced a less satisfactory relationship with the assessing clinician and had lower treatment expectations. Several dimensions measuring severity of presentation did not make a significant contribution to treatment uptake. A logistic regression analysis showed that assessment‐related variables total score and BPD were significant predictors of treatment refusal. The low sample size and the specialist nature of the service are important limitations with regard to the generalizability of the findings. Copyright © 2010 John Wiley & Sons, Ltd.
The β‐silicon effect. 4: substituent effects on the solvolysis of 1‐alkyl‐2‐(aryldimethylsilyl)ethyl trifluoroacetates
Authors: Fujiyama Ryoji , Alam Md. Ashadul , Shiiyama Aiko , Munechika Toshihiro , Fujio Mizue , Tsuno Yuho
Published: March 2010

Solvolysis rates of 2‐(aryldimethylsilyl)‐1‐methylethyl and 2‐(aryldimethylsilyl)‐1‐tert‐butylethyl trifluoroacetates were determined conductimetrically in 60% (v/v) aqueous ethanol. The effects of aryl substituents at the silicon atom on the solvolysis rates at 50 °C were correlated with $\bar {\sigma }$ parameters of r+ = 0.15 with the Yukawa–Tsuno equation, giving ρ values of −1.5 for both secondary α‐Me and α‐tert‐Bu systems. The ρ values for those secondary systems are less negative than −1.75 for the 2‐(aryldimethylsilyl)ethyl system that proceeds by the Eaborn (non‐vertical) mechanism, while they are distinctly more negative than −0.99 for 2‐(aryldimethylsilyl)‐1‐phenylethyl system that should proceed by the Lambert (vertical) mechanism. There was a fairly linear relationship between the reaction constants (ρ) for the β‐silyl substituent effects and the solvolysis reactivities for a series of β‐silyl substrates. The solvolyses of the α‐Me and tert‐Bu substrates proceed through the transition state (TS) with an appreciable degree of the β‐silyl participation, close to the Eaborn (non‐vertical) TS rather than to the Lambert (vertical) TS. Copyright © 2010 John Wiley & Sons, Ltd.
What is the role of friends when contributing care at the end of life? Findings from an Australian population study
Authors: Burns Catherine M. , Abernethy Amy P. , Leblanc Thomas W. , Currow David C.
Published: March 2010

Purpose: To examine the role of friends as caregivers of people with terminal illness.

Method: Piloted questions were included in the 2001–2007 random face‐to‐face annual health surveys of 23 588 South Australians on the death of a loved one, caregiving provided, and characteristics of the caregiver and deceased individual. The survey was representative of the population by age, gender, and region of residence. Analyses focused on friends of the deceased loved one, providing daily or intermittent ‘hands on’ care. Logistic regression assessed predictors of home death.

Results: Daily ‘hands on’ carers were much more likely to be female and aged between 55 and 64; there was also a younger (<age 45) cohort of intermittent ‘hands on’ caregivers. When friends were carers, the deceased was more frequently younger (12 months. Home deaths were more frequent (32%, p=0.014) when friends were carers, and the rate of palliative care use was higher than when family/others provided care (70 vs 61%). Regression analyses confirmed friends as caregivers as a predictor of home death (OR 1.73: 95%, CI 1.15–2.87).

Conclusion: Friends contribute their caregiving: A cohort of younger caregivers may reflect changing social mores as the extended family shrinks and people turn to friendship networks for care and support at the end of life. Copyright © 2010 John Wiley & Sons, Ltd.