ISSN:0730-7268    

DOI:10.1002/etc.5620061001

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe kinetic and equilibrium processes influencing the behavior of organic contaminants in the vicinity of the sediment‐water interface are discussed. These processes include sorption, sediment deposition and resuspension, diffusive and convective movement of contaminants in pore water, and bioturbation. A series of relatively simple mathematical models is presented to illustrate some expected relationships between water and sediment and biota (fish) concentrations. Some implications of these relationships for chemical behavior and bioavailability in aquatic systems are discusse

ISSN:0730-7268    

DOI:10.1002/etc.5620061002

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe earthwormLumbricus terrestriswas exposed to brass powder (70% Cu, 30% Zn) contaminated soils at concentrations ranging from 0 to 430 μg/g. A 14‐d LC50 of 190 μg/g with 95% fiducial limits of 169 and 220 μg/g was determined. Sublethal effects, measured as weight loss, were significantly different (p<.05) from the control at 120 μg/g and

ISSN:0730-7268    

DOI:10.1002/etc.5620061003

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractAs public and scientific interest increases in identifying in vitro alternatives to whole‐animal testing, there is a need to characterize the responses of in vitro systems to defined chemical agents. In this paper we have utilized the medaka (Oryzias latipes) embryo culture system to examine the developmental toxicity of a series of chemically defined model alkylating agents. The medaka embryo culture system was used because it offers numerous advantages over other in vitro embryo systems. This study has examined the developmental toxicity of four model alkylating agents: methylnitrosourea (MNU), ethylnitrosourea (ENU), methyl methanesulfonate (MMS), and ethyl methanesulfonate (EMS). These alkylating agents represent chemical models for compounds that are environmental and occupational pollutants. The embryotoxic parameters that were monitored include embryolethality and specific malformations. Medaka embryos in early organogenesis (stage 20) were exposed for 2 h to the test compound at concentrations ranging from 0.75 to 120 mM. The embryos were cultured at 20°C in Petri dishes and were assessed daily for viability and gross malformations until hatching. All agents tested produced concentration‐dependent decreases in viability and increases in malformations. The developmental toxicity of the four alkylating agents examined is, in order of decreasing potency, MNU>ENU>MMS>EMS. A similar spectrum of malformations was produced following exposure to each alkylating agent; however, agents undergoing first‐order nucleophilic substitution reactions were more potent developmental toxins than those agents which undergo second‐order nucleophilic substitution reactions. Observed abnormalities included flexure, cardiac, optic, and cephalic malfo

ISSN:0730-7268    

DOI:10.1002/etc.5620061004

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractAcute lethality of Al/Zn/Cu mixtures to fry of American flagfish (Jordanella floridae) was reduced by factors of 2.1 to 14.5 in water of pH 5.8 from four lakes of the Canadian Shield, compared to lethality in synthetic soft water. Test waters ranged from clear to dark brown but were otherwise similar. LC50s for total Al/Zn/Cu were correlated with several measurements of humic substances in the lakes, including total organic carbon (TOC), absorbance at 310 nm (A310), color, and Secchi depth. Dialysis techniques showed that toxicity of Al and Cu was reduced by complexation with high‐molecular‐weight (MW) (>1,000) humic substances in the colored water. Zn was present mainly as low‐MW forms and effects of complexation on its lethality were not resolved. Regressions predicted that survival of early life‐stages of fish is doubtful in acidified, soft‐water lakes containing less than 2.2 mg/L of TOC or in whichA310<0.016. Changes in trace‐metal lethality associated with TOC were greater than those associated with changes in tot

ISSN:0730-7268    

DOI:10.1002/etc.5620061005

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractEC50s (calculated concentrations that would inhibit growth by 50%) of 21 pesticides in unicellular algal toxicity tests were calculated by straight‐line graphical interpolation, moving average interpolation, prohibit analysis, and the binomial method. EC50s of 18 tin compounds were calculated by graphical interpolation, moving average, and probit methods. Results from a total of 187 tests were analyzed. The EC50 values were essentially identical when calculated by each method. Although moving average and probit analyses allow calculation of confidence intervals, there is doubt that they can be used with the quantitative data of algal toxicity tests. In the absence of confidence intervals, only the calculated EC50 is used to express relative toxicity, and straight‐line graphical interpolation, a simple and rapid method, may be used in lieu of more complex statistical meth

ISSN:0730-7268    

DOI:10.1002/etc.5620061006

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractAllium cepaL. was grown in soil liquids from beech, birch, and spruce stands of south Sweden. Root growth, cytology, and morphology at different concentrations and speciation of aluminum were studied. A strong cation exchange resin was used to discriminate between toxic and nontoxic species of Al.Root growth was inhibited in all soil liquids compared to controls and was nonlinearly related to the total Al concentration. Cytological changes (i.e., release of nucleolar material into the cytoplasm) were found in certain root tip cells and appeared over the whole Al concentration range of the soil liquids studied. The ion exchange method investigated was able to discriminate between toxic and nontoxic Al in the soil liquid from the mor layer of a podzol (dissolved organic carbon content = 80 mg/L). Labile Al, predominantly corresponding to inorganic monomeric Al forms, made up the toxic Al fraction.

ISSN:0730-7268    

DOI:10.1002/etc.5620061007

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractWe briefly review methods for assessing the impact of forest insecticide spray programs on forest songbirds and discuss the applicabilities of various census techniques. Data obtained on brain acetylcholinesterase enzyme (AChE) levels in live birds collected postspray are reanalyzed. We conclude that these data show a severe collection bias in favor of birds with a low (e.g., approximately below 30% from control) level of AChE inhibition. Possible solutions are discussed. Finally, we suggest that multiyear impact assessment studies involving a number of reproductive parameters are needed to evaluate the effects of nonpersistent insecticides on forest songbirds.

ISSN:0730-7268    

DOI:10.1002/etc.5620061008

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe concept of chronic toxicity has caused confusion in fish toxicology because it has developed four connotations: long duration, inclusion of all life stages, low severity, and high sensitivity. To compare alternate chronic tests and expressions of test results, we extracted concentration‐response data from published life‐cycle, partial‐life‐cycle, and early life‐stage tests and derived concentration‐response relationships by nonlinear regression. The effects examined were reductions in parental survival, fecundity, hatching success, larval survival, weight of early juveniles, and weight of early juveniles per egg. On the average, the most sensitive effect was reduction in fecundity, not effects on early life stages. We also found that maximum acceptable toxicant concentrations (MATCs) corresponded to fairly high levels of effect; mean reductions at the MATC were parental survival, 20%; fecundity, 42%; hatching, 12%; larval survival, 19%; weight, 20%; and weight/egg, 35%. These results indicate that, on average, MATCs are concentrations that cause substantial effects and that MATCs estimated from early life‐stage tests are not good substitutes for life‐cycle tests. We suggest that the acute‐chronic dichotomy be abandoned in favor of tests and benchmarks based on concentration‐duratio

ISSN:0730-7268    

DOI:10.1002/etc.5620061009

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractIn assessments of risks of toxic contaminants to fish populations, the endpoints of ultimate interest are the persistence, abundance, and production of populations. In this article we demonstrate a method for expressing toxicity test data obtained from full‐life‐cycle tests in terms of the same indices used to assess effects of harvesting and power‐plant cooling systems on fish populations. Our approach involves fitting the logistic concentration‐response function to chronic test data and coupling the functions obtained to a fish life‐cycle model. Confidence bands derived from the data quantify uncertainties inherent in predicting population‐level effects from (1) full‐life‐cycle test data for the species of interest, (2) extrapolation of a concentration‐response function from an acute LC50 for the species of interest, and (3) extrapolation from an acute LC50 for another species. Using rainbow trout and largemouth bass as representative species, we evaluate the relative importances of three sources of uncertainty contributing to prediction intervals for populationlevel effects. We also compare population‐level concentration‐response functions to predicted and experimentally derived maximum acceptable toxicant concentrations for

ISSN:0730-7268    

DOI:10.1002/etc.5620061010

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY