ISSN:0730-7268    

DOI:10.1002/etc.5620101001

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA brief overview is given of the approach to biodegradation testing adopted by the European Economic Community (EEC) as part of the legislation on new chemicals. The tiered system of screening and simulation tests is outlined and the various tests are discussed briefly. It is concluded that the test strategy is logical and cost‐effective, but that ongoing work to further harmonize and revise screening tests for ready biodegradability must be completed before these tests perform satisfactorily. The principles governing simulation tests should be further developed, and, in particular, the importance of the applied concentration of test chemical should be addresse

ISSN:0730-7268    

DOI:10.1002/etc.5620101002

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractLead chromate pigments can be encapsulated within an amorphous silica coating. This reduces both the chemical teachability and the biological availability of the constituents. The chromate moiety is inactive in in vitro mutagenicity assays, even in the presence of a strong chelating solubilizer under conditions where the unencapsulated material gives positive results. Rodent feeding studies demonstrate much reduced absorption of both lead and chromium from the encapsulated lead chromate compared to the analogous unencapsulated material. Encapsulation also reduces the leachability of both lead and chromium in tests used to define the applicable environmental disposal methods for lead chromate pigments. These findings have important implications for health and environmental issues surrounding the use of lead chromate as a pigment material.

ISSN:0730-7268    

DOI:10.1002/etc.5620101003

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe reductive dechlorination of three dichlorophenol (DCP) isomers was studied in anoxic sediments collected every other month for a year from five sites in one pond. Several physical, chemical, and microbiological characteristics of the sediments also were determined to identify correlations with DCP dechlorination that may be used to predict the persistence of these compounds in anoxic sediments. Stepwise regression indicated that for 2,5‐ and 3,4‐DCP, sediment pH, redox potential (Eh), and concentration of sulfate and nitrate accounted for 83% of the variation inT50values (time for dechlorination of 50% of a DCP to a monochlorophenol). Although the number of sediment microorganisms that dechlorinate 2,4‐DCP varied two orders of magnitude in sediments collected during the study year, regression analysis indicated that neither this nor any other variables could account for greater than 50% of the variation inT50values for 2,4‐DCP. Chlorine was preferentially removed from the aromatic ring in the order ortho>para>meta; however, the influence of chlorine position on the ring on the persistence of the DCPs was generally not statistically sign

ISSN:0730-7268    

DOI:10.1002/etc.5620101004

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe octanol/water partition coefficient of cadmium was measured in the presence of ethyl‐, isopropyl‐, isobutyl‐, and amylxanthates and diethyldithiocarbamate. For each complexing agent, the threshold concentration at which hydrophobic cadmium complexes started to appear was established. Cadmium was shown to form hydrophobic complexes with xanthates and diethyldithiocarbamate (maximal logPOW= 1.73–2.64) at total ligand concentrations of 10−6to 10−1M. The proportion of cadmium in the octanol phase began to increase within the range of approximately 10−6.5to 10−6M for xanthate and approximately 10−5.0M for dieth

ISSN:0730-7268    

DOI:10.1002/etc.5620101005

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractSoil columns were used to investigate leaching of atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] in a Plainfield sandy soil amended with waste activated carbon (WAC), digested municipal sewage sludge (DMS), or animal manure. Lower amounts of atrazine were consistently observed in leachates from soil with amendments than from soil without amendments. Ability of the three wastes to reduce leaching of atrazine followed the order WAC ≫ DMS>animal manure. Atrazine recovery in leachate ranged from 0.1% from soil amended with WAC at 2.1 t of total carbon per ha (t C/ha) to 77.4% from unamended soil. Mobility of atrazine in amended soil was inversely related to its sorption coefficient,KOC. Reduction in amount of leached atrazine by application of DMS or manure may also have involved increased degradation and/or formation of bound residues. Findings of this study provide basic information for possible utilization of waste materials in coarse‐textured soils to reduce leaching of pesticide

ISSN:0730-7268    

DOI:10.1002/etc.5620101006

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractBond contribution values, used to estimate Henry's law constant (HLC) (air‐to‐water partition coefficient) from chemical structure, have been determined for 59 chemical bonds by a least‐square analysis of known HLCs for 345 organic compounds. A correlation coefficient (r2) of 0.94 was determined for the relationship between known LWAPCs (log water‐to‐air partition coefficients) and bond estimated LWAPCs for the 345 compound data set. The correlation coefficient increases to 0.97 when quantified correction factors are applied to selected chemical classes. The ability of the bond method to estimate LWAPCs is demonstrated by a validation test set of 74 diverse and structurally complex compounds that were not included in the least‐squares analysis. The correlation coefficient for the validation

ISSN:0730-7268    

DOI:10.1002/etc.5620101007

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractLog‐transformed values of lethal effect and hardness are often employed to predict metal effects. For example, they are used to develop water quality criteria. A statistical bias encountered with backtransformed, least‐squares regression models can compromise the accuracy of associated predictions. A description and method of estimating this bias are discussed herein. In a selected data set, the bias was as high as

ISSN:0730-7268    

DOI:10.1002/etc.5620101008

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractWe investigated the influence of sulfide, measured as acid‐volatile sulfide (AVS), on the bioavailability of cadmium and nickel in sediments. Seventeen samples from an estuarine system heavily contaminated with cadmium and nickel were analyzed for AVS and simultaneously extracted metals (SEM) and tested in 10‐d exposures with the amphipodHyalella aztecaand the oligochaeteLumbriculus vanegatus.Molar SEM (cadmium + nickel)/AVS ratios in the sediments ranged from less than one to greater than 200, with several in the range of 1 to 10. Samples with SEM/AVS ratios greater than one were consistently toxic toHyalella azteca, whereas sediments with ratios less than one were not.Lumbriculus variegatuswas less sensitive to the test sediments thanHyalella azteca, which was consistent with their relative sensitivity to cadmium and nickel in water‐only exposures. SEM/AVS ratios in the sediments also appeared to be important in determining bioaccumulation of metals byLumbriculus variegatus.These results support other studies with metal‐spiked samples in demonstrating the importance of AVS in determining metal bioavailability in sediments and suggest that AVS normalization is a reasonable means for assessing the hazard of some sediment‐associated metals to aquatic e

ISSN:0730-7268    

DOI:10.1002/etc.5620101009

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe objective of this study was to determine if the acid‐volatile sulfide (AVS) content of freshwater sediments was important in limiting the bioavailability and toxicity of cadmium. Five different concentrations of cadmium were spiked into sediments with three different AVS concentrations, and 10‐d exposures with the oligochaeteLumbriculus variegatusand the snailHelisomasp. were conducted. Concurrent water‐only cadmium exposures were also conducted. When the cadmium‐to‐AVS ratios were ≤1, toxicity was not observed. At ratios ≤1, mean whole‐body cadmium residue concentrations of organisms were approximately equal to or less than the maximum residues obtained in survivors of the cadmium exposures in water only. These results corroborated the results of a previous experiment conducted with saltwater sediments and indicate that metal/AVS relationships could be used to establish numeric sediment quality criteria for use in the protection

ISSN:0730-7268    

DOI:10.1002/etc.5620101010

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY