ISSN:0730-7268    

DOI:10.1002/etc.5620050901

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractA gas‐liquid chromatographic method was modified to quantify both unmetabolized (“free”) and metabolized (“bound”, i.e., thiocyanates) cyanides. The methods for both are efficient and sensitive to 0.05 ppm. Repeated freezing and thawing of whole blood from treated cathartids caused an initial increase in free cyanide concentrations, followed by a gradual decline to a plateau. Bound cyanide concentrations declined after repeated freezing an

ISSN:0730-7268    

DOI:10.1002/etc.5620050902

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractSeasonal effects on microbial transformation rates of an herbicide, 2,4‐dichlorophen‐oxyacetic acid butoxyethyl ester (2,4‐DBE), in a freshwater stream were investigated using low concentrations (less than 100 μg L−1) of the herbicide mixed with an inert dye, rhodamine WT, to correct for dilution. Although water temperatures decreased from 22 ± 0.5 to 8.0 ± 0.5°C and water velocities decreased from 0.09 ± 0.01 to 0.03 ± 0.003 m s−1, microbial transformation rates, as indicated by pseudo‐first‐order transformation rate coefficients, increased as much as threefold in the cold months over those in the spring and summer. The increased winter transformation rates were associated with leaf‐litter accumulation, which provided additional colonized surface area in the stream. Therefore, the increased colonized surface area more than compensated for the effects of temperature and water velocity (under conditions of mass‐transport limitation) that otherwise would have reduced microbial transformation rat

ISSN:0730-7268    

DOI:10.1002/etc.5620050903

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractSimple and multiple linear regressions were applied to the development of models for predicting biodegradability of chemicals from molecular connectivity indexes. Indexes were calculated using the program CFUNC, on the DECsystem 10 computer at the National Institutes of Health, Bethesda, Maryland. Biodegradation data from test systems containing natural media or inocula were obtained from the literature for several homologous series of organic compounds; within each series, all compounds had been tested under the same conditions. The following one‐variable models were among those obtained: for 2,4‐D alkyl esters, log rate constant versus2Xv,r2= 0.954 (n= 6); forN‐3‐chlorophenylcarbamates, log percent degraded versus4Xp/c,r2= 0.971 (n= 7); for dialkyl ethers, log percent theoretical oxygen demand (%ThOD) versus2Xv,r2= 0.974 (n= 6); for dialkyl phthalate esters, rate constant versus2X,r2= 0.938 (n= 12); for aliphatic acids, %ThOD versus4Xc,r2= 0.895 (n= 10). Two‐variable models substantially improved results for aliphatic alcohols and acids. These results indicate that the apparent effect of alkyl chain branching on biodegradability can be quantitatively described by connectivity indexes, especially2X,3Xc,4Xcand4Xp/c,3Xpalso appeared frequently, especially in two‐variable models, suggesting a possible role for molecular shape as a determinant of biodegradability. The results suggest that molecular topology holds promise for future research in quantitative structure‐biodegradability

ISSN:0730-7268    

DOI:10.1002/etc.5620050904

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThree snail species collected from western Oregon were exposed to metals—Juga pliciferaandLithoglyphus virens, which inhabit cool coastal streams, andPhysa gyrina, which is found in Willamette Valley ponds.J. pliciferawere exposed in flow‐through laboratory tests to copper and nickel,L. virenswere exposed to copper, andP. gyrinawere exposed to nickel and zinc.J. pliciferahad a 96‐h LC50 (50% of the test group died) of 0.015 mg/L for copper and a no observed effect level (NOEL, mortality not significantly different from that in control groups) of 0.006 mg/L (30‐d survival).J. pliciferahad a 96‐h LC50 for nickel of 0.237 mg/L and a NOEL of 0.124 mg/L.L. virenshad a 96‐h LC50 for copper of 0.008 mg/L and a NOEL of less than 0.008 mg/L.P. gyrinahad a 96‐h LC50 for nickel of 0.239 mg/L, a 96‐h LC50 for zinc of 1.274 mg/L and a NOEL for zin

ISSN:0730-7268    

DOI:10.1002/etc.5620050905

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractStatic, acute toxicity tests were conducted with mysids (Mysidopsis bahia) and 11 used drilling fluids (also called drilling muds) obtained from active drilling platforms in the Gulf of Mexico in U.S. waters. Each whole mud was tested, along with three phases of each mud: a liquid phase with particulate materials removed, a suspended particulate phase composed of soluble and lighter particulate fractions and a solid phase composed mainly of drill cuttings and rapidly settling particulates. These muds represented seven of the eight generic mud types described by the U.S. Environmental Protection Agency for use on the U.S. outer continental shelf.Based on volume: volume preparations of the drilling muds in seawater, the lowest 96‐h LC50s obtained were 26 μl/L for whole mud, 11,400 μl/L for the liquid phase, 726 μl/L for the suspended particulate phase and 1,456 μg/L for the solid phase. The toxicity of the 11 muds tested was apparently increased by the presence of aliphatic compo

ISSN:0730-7268    

DOI:10.1002/etc.5620050906

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractFood avoidance experiments could contribute to assessments of animals' behavioral responses to environmental toxicants. Food avoidance tests with mallards (Anas platyrhynchosL.) and northern bobwhite (Colinus virginianusL.) as the test species were patterned after avian 5‐d dietary LC50 tests. Animals in each treatment group were given free access to untreated feed and feed treated with various concentrations of methiocarb (3,5‐dimethyl‐4‐(methylthio)‐phenyl methylcarbamate), a widely used bird repellent. Prior to food avoidance testing, 5‐d dietary LC50 tests were conducted to provide baseline data for comparison. A measure of avoidance response was estimated from a log (dose)‐probit (response) analysis. The percentage of total (treated plus untreated) feed consumption as treated feed consumption was the response variable. The detectable dietary concentration at which mallards and bobwhite began to avoid a specific contaminant was determined by calculating a median food avoidance concentration 50 (FAC50). In the absence of detectable avoidance behavior, test animals' total feed consumption can be expected to consist of equal amounts of treated and untreated feed. An effective avoidance index (EAI), LC50/FAC50, was used as a measure of a toxicant's “margin of safety.” Calculated results for methiocarb were as follows: for mallard, LC50 = 7,469 ppm, FAC50 = 145 ppm, EAI = 51.5; for bobwhite, LC50 = 827 ppm, FAC50 =

ISSN:0730-7268    

DOI:10.1002/etc.5620050907

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractA cost‐effective testing procedure is described that measures the acute aquatic effects of a single test chemical on seven aquatic species simultaneously:Asellus intermedius(pillbug),Daphnia magna(water flea),Dugesia tigrina(flatworm),Gammarus fasciatus(sideswimmer),Helisoma trivolvis(snail),Lumbriculus variegatus(segmented worm) andPimephales promelas(fathead minnow). These species were chosen because of their ecological importance, diversity and amenability to laboratory culturing. Twenty‐seven commercial inorganic and organic chemicals were tested using the simultaneous exposure procedure. The 96‐h LC50 values were derived for each species and the results compared with literature values. The reproducibility of the results achieved using this testing procedure was shown to be very good. The results compare favorably with 96‐h LC50 values from single‐species tests.The susceptibility of test animals as a function of species and chemical compound was evaluated. Water fleas were found to be as susceptible as, or more so than, the other aquatic organisms for all compounds tested. The relative sensitivities of the other test species were found to be highly chemical

ISSN:0730-7268    

DOI:10.1002/etc.5620050908

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractMargins of uncertainty in predicting toxicity from one species to another, from acute to chronic exposures and from single species to higher levels of biological organization were determined by regression and correlation analyses. Based on the acute sensitivities of 35 aquatic species to 15 compounds, no species was found to be particularly sensitive to all chemicals and the 95% uncertainty factor (UF) ranged from 3 to 1,985. Analyses of acute and chronic sensitivities for the same species to 164 chemicals resulted in the acute/chronic relationship log NOEC = ‐1.28 + 0.95 log L(E)C50 (r= 0.89) and the UF of 25.6 (where NOEC is the no observed effect concentration). Comparison of the lowest acute and corresponding ecosystem effect levels for 34 chemicals indicated the relationship log NOEC(ecosystems) = ‐0.55 + 0.81 log L(E)C50 (r= 0.77) and the UF of 85.7. As to the predictability of ecosystem effect levels from chronic single‐species data, the following relationship was found: log NOEC(ecosystems) = 0.63 + 0.85 log NOEC (r= 0.85), with a UF of 33.5. These data indicate that acute testing is not pointless; it offers a statistical base for the use of acute toxicity information in the hazard assessment of chemicals in the aquatic enviro

ISSN:0730-7268    

DOI:10.1002/etc.5620050909

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY

摘要:

AbstractThree commercial triaryl phosphates, Pliabrac 521, Reofos 95 and Reolub hyd 46, were tested for acute toxicity against the brackish‐water harpacticoidNitocra spinipesBoeck (Crustacea) and the zebra fish,Brachydanio rerioHamilton‐Buchanan. The 96‐h LC50 values ranged from 0.27 to 1.75 mg/L, with Pliabrac 521 as the most toxic and Reolub hyd 46 as the least toxic. The zebra fish was more than 10 times less sensitive to the tested compounds than wasN. spinipes.Low to moderate accumulation of triaryl phosphates was observed. An accumulation factor (AF) of 100 to 2,000 was observed for Pliabrac 521 from water to bleak,Alburnus alburnusL. For the various triaryl phosphates, a dietary accumulation of 0.06 to 0.6 from food to minnow,Phoxinus phoxinusL., was observed. The most hydrophilic compounds were readily cleared from fish when the fish were placed in clean water, whereas the most lipophilic ones were still detectable, albeit in low concentrations, in the fish after a 2‐week depuration period. A rotatory‐flow behavioral study did not reveal any effects on swimming performance in the bleak, but reproduction was affected as a result of long‐term (163 d) exposure of minnows to subacute concentrations of P

ISSN:0730-7268    

DOI:10.1002/etc.5620050910

出版商:Wiley Periodicals, Inc.    

年代:1986

数据来源: WILEY