ISSN:0730-7268    

DOI:10.1002/etc.5620070601

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe adsorption and desorption of oligomers of cationic poly(ethylenimine) (PEI) a poly(N,N‐dimethylaminoethyl methacrylate) (PDAM) were measured on several sediments. The adsorption isotherms have a Langmuir shape, with high initial slopes for PEI and adsorption capacities of up to 13% oligomer adsorbed by weight for PDAM. Sorption capacity correlates with the cation exchange capacity for both oligomers. Sorption capacity increases with PEI molecular weight but is independent of PDAM molecular weight. Adsorption/desorption reversibility is less than 15% at all surface coverages for PDAM and for PEI at low surface coverage, but increases up to 50% for PEI at high surface coverage. These data indicate that PDAM adsorbs with all protonated nitrogens directly attached to cation exchange sites at all surface coverages. In contrast, PEI appears to adsorb with a significant mass of adsorbed material in loops and tails indirectly attached to the surface. Adsorption of PDAM appears to increase dramatically if the sediment pH is basic enough to allow bilayer adsorption in the interlamellar region of the sediment. Preadsorption of PDAM on a sediment significantly increased the adsorption of naphthalene from water, suggesting that the lipophilicity of sediments or soils can be substantially increased by oligomer adsorptio

ISSN:0730-7268    

DOI:10.1002/etc.5620070602

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe methods employed to determine critical stability constants from the published literature are described and the best approach for estimating stability constants to establish a sufficiently broad and extensive database that substantially defines all of the metal complex systems encountered in the environment is recommended. With these estimated formation constants, it is possible, with modern computer techniques, to calculate the speciation and concentrations of the metal complexes in multicomponent systems containing thousands of ligands and 10 to 100 times that number of metal complex species. The structure‐stability relationships developed by other investigators are compared with the methods employed herein. Examples of measured, selected and estimated constants are presented for several metal complexes. The distributions of metal complex species in seawater in the absence and presence of an added complexing pollutant are calculated to illustrate the use of the stability constant database and the adjustment of the constants to the conditions required (i.e., ionic strength) for the system under consideratio

ISSN:0730-7268    

DOI:10.1002/etc.5620070603

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA structure—activity relationship developed for the estimation of rate constants for the gas‐phase reactions of the hydroxyl radical with organic compounds is described and extended to certain organophosphorus compounds. The use of this estimation method is illustra

ISSN:0730-7268    

DOI:10.1002/etc.5620070604

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractMeasurements of the median lethal dose (LD50) of chemicals to fish provide a simpler, faster and less expensive alternative to median lethal concentrations (LC50s). Since dose is controlled, LD50s may be a better basis for structure‐activity relationships. However, LC50s are used extensively in aquatic hazard assessments. Therefore, LC50s and LD50s for rainbow trout of 48 organic chemicals were measured to determine whether LC50 could be predicted from LD50. A simple linear regression of log‐transformed data provided the best fit (r= 0.70), but it accounted for only 50% of the variability in LC50s. LC50s were also strongly correlated with measures of molecular size [molecular weight (MW;r= −0.90) and Parachor (r = −0.89)] and of water‐lipid partitioning [octanol‐water partition coefficient (Kow;r= −0.73)]. Hence, inclusion of these factors in a multiple regression analysis was examined. Since MW and Parachor were negatively correlated with LD50 (r= −0.61 and −0.60, respectively), they were not true independent variables and were not used. However, there was no relationship of Kowwith LD50, and a multiple regression analysis using both LD50 and Kowpredicted LC50 with greater certainty (r= 0.92) than did either factor alone. Therefore, LC50 can be predicted from LD50 when partitioning of a chemical from water to li

ISSN:0730-7268    

DOI:10.1002/etc.5620070605

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe incorporation of structure‐activity relationships and other estimation methods in a computer format is a logical and necessary step in handling the complex problem of setting priorities for existing chemicals in a feasible, systematic way. In combination with an appropriate hazard ranking methodology, the computer format is a useful tool for selecting existing chemicals for further testing and more detailed assessment. Recent developments and applications of a proposed system for setting priorities for existing chemicals are discussed, along with the system's expected reliability and limitations. Important gaps that now exist in our understanding of the relationships between structure and physicochemical and toxicological properties, as well as reactivities, are pointed out. Selected chemicals are cited in examples of the application of the new computer‐assisted methodol

ISSN:0730-7268    

DOI:10.1002/etc.5620070606

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA correlation approach was developed to describe narcosis in several aquatic species. By assuming that narcosis occurs as a result of a constant volume fraction of toxicant at the target site in the test organism, it is possible to correlate LC50s for a series of chemicals with their octanol‐water partition coefficients and molar volumes. The approach was successfully tested on acute and chronic toxicity data from the published literature. Two hundred‐fourteen toxicity determinations, with 113 different organic chemicals and involving fathead minnow (Pimephales promelas), guppy (Poecilia reticulata), golden orfe (Leuciscus idus melanotus), water flea (Daphnia magna), brine shrimp (Anemiaspp.) and Paramecium (Tetrahymena elliotti), were employed.The data analysis suggests that partition coefficients of the chemicals between the target phase, i.e., the site of toxicant action, in the test organism and water are similar to, but generally lower than, octanol‐water partition coefficients. The analysis also suggests a method of correlating the toxicities of mixtures and provides an explanation of the “toxicity cut‐off” frequently observed in toxicity tests with chemicals of low water solubility. The interpretation provides insights into the role of partitioning in the acute and chronic effects of nonselective narcoti

ISSN:0730-7268    

DOI:10.1002/etc.5620070607

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe relative sensitivities and discrimination abilities of theDaphnia magna48‐h lethality assay of sediment pore water, thePhotobacterium phosphoreum15‐min bioluminescence inhibition (Microtox®) assay of sediment pore water and theChironomus tentans10‐d growth reduction assay of whole Detroit River sediments were investigated and predictive relationships developed. While all three assays demonstrated the toxicity of some sediments and all of them identified the most and least toxic sediments, theD. magnalethality assay was the least sensitive and discriminatory. The Microtox® assay was the most sensitive. Based on lethality, theC. tentansassay was less sensitive thanD. magna, but growth inhibition was sensitive and the most discriminatory of the three assays. Chironomids were not observed in the sediments that caused a 30% decrease in growth ofC. tentansrelative to that on control sediment in which chironomids were observed. This sediment toxicity is also approximately that which killsD. magna. Some locations were deemed very toxic by one or two assays but not toxic by the others. The results of all of the assays were correlated, but none of the assays accurately predicted the results of the other two. It was concluded that theD. magnalethality test could be used to predict which sediments were so toxic that benthic insects would not be expected to be present. A principal components analysis demonstrated that the Microtox® assay gave sufficiently different information that it could be included in a battery of sediment toxicity tests designed to accurately classify the toxicities of s

ISSN:0730-7268    

DOI:10.1002/etc.5620070608

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractHalf the young in each of four broods of 5‐d‐old mallards (Anas platyrhynchos) were gavaged orally with 4 mg/kg methyl parathion and released with their mother and untreated siblings in pond enclosures. Four control broods received corn oil only. Activity categories (swimming, preening, feeding, loafing) of hens and broods were noted every 15 min and continuous observations were made of length of time to recovery or death (dosed ducklings) and of time spent in a behavior. Observations were made for 4 h following release, for an additional 2 to 4 h that afternoon, and for 2 h the following morning. Control broods were on water during 22 of 37 observations, while treated broods were on land more frequently than on water (43 of 51 observations). There was a significant difference (χ2= 76.4,p<0.001) between behaviors of treated and control broods; treated broods mostly preened and loafed on land while control broods primarily fed and swam in open water. Hens remained with their broods and kept all ducklings together even when dosed young were too sick to move (for 90 to 155 min posttreatment). Forty percent of dosed ducklings died the first day, whereas no control ducklings died. The results of this study indicate that methyl parathion can affect the brood‐rearing phase of reproduction by direct mortality and through behavioral c

ISSN:0730-7268    

DOI:10.1002/etc.5620070609

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractSensitivities of bluegill (Lepomis macrochins), channel catfish (Ictalurus punctatus) and fathead minnow (Pimephales promelas) to pH and aluminum were compared during 96‐h acute toxicity tests in the laboratory. Juveniles were exposed to four HCl (pH 4.5, 5.5, 6.5, 7.5 nominal) and five AlCl3(0, 50, 100, 200, 400 μg/L nominal) treatments in moderately soft fresh water (total hardness, 20 to 25 mg/L CaCO3) under continuous flow‐through conditions. The ranking of species sensitivities to acid alone was fathead minnow (most sensitive), followed by channel catfish and bluegill (about equally sensitive). Aluminum was not toxic to these species at pH 6.5 and 7.5. The ranking of sensitivities to Al at pH 4.5 and 5.5 showed clearer species differences. Fathead minnow were most sensitive and died in all Al treatments. Bluegill were least sensitive and died only in the highest Al concentration at pH 5.5. The sensitivity of channel catfish to Al was intermediate, but was most similar to that of fathead minnow. Aluminum, predominantly as hydroxide species, appeared to be most toxic to bluegill at pH 5.5. Free and hydroxy Al species were apparently toxic to fathead minnow and channel catfish at pH 4.5 and 5.5. Our experimental data corroborate the observed distributions of these species in acidified lakes and str

ISSN:0730-7268    

DOI:10.1002/etc.5620070610

出版商:Wiley Periodicals, Inc.    

年代:1988

数据来源: WILEY