ISSN:0730-7268    

DOI:10.1002/etc.5620060601

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractFrog eggs were exposed to di‐2‐ethylhexylphthalate (DEHP) added to the sediment in laboratory model systems. The number of successful hatchings decreased as the DEHP concentration was increased. In tadpoles, the uptake was concentration‐dependent. The phthalate ester was transported from the sediment to the water, and the extent of the transport was governed by levels of DEHP in the sediment. Our results show that the reproduction of frogs may be negatively affected in aquatic environments polluted with phtha

ISSN:0730-7268    

DOI:10.1002/etc.5620060602

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractMallards(Anas platyrhynchos)were fed diets containing 1, 5, 10, 25 or 100 ppm selenium as sodium selenite, a diet containing 10 ppm selenium as seleno‐DL‐methionine or a control diet. There were no effects of 1, 5 or 10 ppm selenium as sodium selenite on either weight or survival of adults or on reproductive success, and there did not appear to be a dose‐response relationship at these lower levels. The 100 ppm selenium diet killed 11 of 12 adults; one adult male fed 25 ppm selenium died. Selenium at 25 and 100 ppm caused weight loss in adults. Females fed 25 ppm selenium took longer to begin laying eggs and intervals between eggs were longer than in females in other treatment groups. Hatching success appeared to be reduced in birds fed 10 ppm selenium as selenomethionine, but the reduction was not statistically significant. The survival of ducklings and the mean number of 21‐d‐old ducklings produced per female were reduced in the 25 ppm selenium as sodium selenite group and the 10 ppm selenium as selenomethionine group. Egg weights were not affected by any selenium treatment, but 25 ppm selenium lowered the Ratcliffe Index. Duckling weights at hatching and at 21 d of age were reduced 28 and 36%, respectively, in birds fed 25 ppm selenium, as compared with controls. Body weights measured on day 21 were lower for ducklings fed 10 ppm selenium as selenomethionine than in some other groups. Selenium in concentrations of 10 and 25 ppm as sodium selenite caused mainly embryotoxic effects, whereas 10 ppm as selenomethionine was more teratogenic, causing hydrocephaly, bill defects, eye defects (microphthalmia and anophthalmia) and foot and toe defects, including ectrodactyly. Selenomethionine was much more readily taken up by mallards and passed into their eggs than was sodium selenite, and a greater proportion of the selenium in the eggs ended up in the white when selenomethionine was fed. Adult males accumulated more selenium than did females, probably because of the females' ability to eliminate selenium in t

ISSN:0730-7268    

DOI:10.1002/etc.5620060603

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe value of hexavalent chromium as a reference toxicant was investigated by comparing the precision of two laboratories in preparing test solutions, examining the consistency of chromium exposure in the test chambers during experiments and determining the effect of nominal versus measured test concentrations on the calculated toxicity (EC50 or LC50). The sensitivities of the test animals to chromium were also determined.The coefficients of variation associated with preparing chromium test concentrations were 51 and 63.8% in salt and fresh water, respectively, at one laboratory, and 136 and 14.8%, respectively, at the other laboratory. Hexavalent chromium remained stable in the hexavalent (as prepared) form during the toxicity test, with recoveries ranging from 77 to 114%. The precision of the analytical laboratory in measuring chromium‐spiked fresh and salt waters ranged from 0.2 to 9.1%. The impact on the calculated EC50s or LC50s of using analytically measured versus nominal concentrations in the analyses was negligible. A comparison of seven species in 27 tests showed organism sensitivity (mean EC50 or LC50 as mg/L Cr6+) to chromium to be, in decreasing order of sensitivity:Ceriodaphniasp. (0.031),Daphnia pulex(0.086),Mysidopsis almyra(5.1),Mysidopsis bahia(6.03),Cyprinodon variegatus(21.4),Pimephales promelas(26.1) andLepomis macrochirus(182.9).The 48‐h LC50s forM. bahiawere not significantly different (p<0.05) either within or between laboratories during a 3‐week study; values ranged from 5.49 to 7.72 mg/L Cr6+in both laboratories (nominally) and from 4.21 to 7.23 mg/L Cr6+when analytically verified by an independent laboratory. The acute toxicities of chromium toD. pulexdiffered significantly between laboratories, by almost one order of magnitude. Interlaboratory variability observed inD. pulextests was attributed to differences in the test organisms' food. As reference toxicant tests, chromium tests are valuable benchmark indices of the relative health of test organisms over time or among laboratories. When toxicity test information is used in critical decision making, such as compliance with effluent permit limitations, a reference toxicant such as chromium contributes to quality control and assu

ISSN:0730-7268    

DOI:10.1002/etc.5620060604

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe photodynamic, actue toxicities of 20 polycyclic aromatic hydrocarbons (PAHs) toDaphnia magnawere predicted by photophysical and physiochemical parameters. The photophysical parameters considered were lowest singlet energy, lowest triplet energy, singlet‐triplet splitting energy and phosphorescence lifetime. The physiochemical parameters were first‐ and second‐order connectivity indices and logPvalues.D. magnawere exposed to aqueous solutions of each PAH such that equimolar concentrations inD. magnawere achieved. The organisms and the PAHs were then exposed to 120 μW/cm2UV‐A and 25 μW/cm2UV‐B light. Mortality times (min) were recorded and the results reported as median lethal time (LT50). Potency factors (π) were calculated and used to rank the PAHs in terms of relative photodynamic toxicity. Some statistically relevant correlations between individual physical parameters and toxicity were observed. Linear, multiple regression models were poor predictors of photoinduced PAH toxicity. A curve‐linear model was developed to predict photoinduced toxicity from triplet energy. Goodness‐of‐fit chi‐square tests were performed and demonstrated that triplet energy was an effective predictor both of observed LT50 and of LT50 values adjusted to a constant PAH concentration. Toxicity data were also analyzed using discriminant functional analysis. A stepwise, canonical correlation parameter selection method separated the PAHs into three toxic categories by using triplet energy and phosphorescence lifetime as variables. This model, which classifies PAHs as very toxic, moderately toxic or nontoxic, was 100% accurate when the model developed from one set of PAHs was tested

ISSN:0730-7268    

DOI:10.1002/etc.5620060605

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractGeneric mixed‐flask microcosms were used to evaluate ecosystem responses to aniline and three closely related compounds—2,6‐diisopropylaniline, 4‐hexyloxyaniline and 2,3,5,6‐tetrachloroaniline. Toxicity was determined on both an acute and chronic basis using changes in ecosystem‐level variables (pH and dissolved oxygen levels) as indicators of effect. These calculated toxicity values were then compared with reported toxicity data on bacteria, algae, protozoa and Cladocera to evaluate the relative sensitivity of the method. The relative toxicities of the tested compounds were the same in microcosm tests as in the available single‐species tests, but the range between the most and least toxic as determined by the microcosm test was smaller by an order of magnitude. Aniline was the least toxic, followed, in order of increasing toxicity, by 2,6‐diisopropylaniline, 4‐hexyloxyaniline and 2,3,5,6‐tetrachloroaniline. The minimum effect concentrations determined for these compounds were generally lower than reported literature values, suggesting that the method does not sacrifice sensitivity in providing an integrated picture of ecos

ISSN:0730-7268    

DOI:10.1002/etc.5620060606

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractCationic polyelectrolytes comprise a large group of chemicals designed to react with and flocculate suspended solids. Their primary use is as water clarification aids in the removal of suspended solids from water supplies and from industrial and domestic effluents entering receiving waters. Many of these water‐soluble macromolecules exhibit an acute toxicity to aquatic organisms of less than 1.0 mg/L. The interaction of residual amounts of these polymers in receiving waters is unclear. The effects of suspended solids (bentonite, illite, kaolin and silica) and of dissolved organic carbon compounds (humic, fulvic and tannic acids, lignin and lignosite) on the acute toxicities of four cationic water clarification aids to the fathead minnow(Pimephales promelas)and a cladoceran(Daphnia magna)were determined. Bentonite and all of the dissolved organic carbon compounds reduced the toxicities of the polymers by one to two orders of magnitude. The remaining suspended solids had a lesser effect in reducing toxicit

ISSN:0730-7268    

DOI:10.1002/etc.5620060607

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractMethods for modeling short‐term (time‐variable) and long‐term (time‐averaged) exposures in the upper mixed layer that may result from the proposed disposal of sewage sludge at the 106‐Mile Ocean Disposal Site are presented. The models have not been field validated at the 106‐Mile Site, but they do provide decision makers with “upper‐bound” estimates of risk to the upper water column from municipal sludge loadings currently projected for disposal at the site. The methods are believed to be useful in managing disposal site operations and in determining if future loadings to the site would be permissible.The models are two‐dimensional in the horizontal plane and assume complete mixing over a prescribed mixed‐layer depth. Upper‐bound estimates of sludge contaminant concentrations in the upper mixed layer were based on summer hydrographic conditions and an annual disposal rate of 7.2 million metric wet tons of sludge. Preliminary assessments of the potential effects of the sludge disposal were made using U.S. Environmental Protection Agency marine water quality criteria, the Food and Drug Administration tolerance level for polychlorinated biphenyl residues in edible portions of fish tissue and whole‐sludge toxicity test results. Within the framework of the assumptions and limitations of this analysis, and based on the projected loading rate, the overall results indicate that there would be no violations of these criteria. The margins of safety relative to the specifie

ISSN:0730-7268    

DOI:10.1002/etc.5620060608

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY