ISSN:0730-7268    

DOI:10.1002/etc.5620061201

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reductive transformation of azobenzene and selected derivatives was investigated in anaerobic sediment/water systems. The azo compounds exhibited pseudo‐first‐order disappearance kinetics through at least three half‐lives. The reduction kinetics of these compounds was studied as a function of their reduction potential and sediment/water distribution coefficient. There was no apparent correlation between the observed disappearance rate constant and reduction potential. In general, as the distribution coefficient increased, the rate of reduction decreased. Values for the pseudo‐first‐order rate constant for disappearance ranged from 5.11 × 10−3min−1for methyl red to 6.03 × 10−6min−1for 4,4′‐dichloroazobenzene. Removal of the solid phase from the sediment/water samples gave a filtrate with little or no reactivity. Chemical sterilization of the sediment/water sample with formaldehyde and treatment withm‐cresol, a dehydrogenase inhibitor, or sodium azide, a metabolic inhibitor, had little effect on the observed reduction rate constants for azobenzene, indicating an abiotic reduction process. Heat sterilization indicated that the reducing agent was heat labile. In studies with 4,4′‐dimethoxyazobenzene, the observed rate constant for reduction increased with increasing sediment concentration. Based on the results of these studies, a model for the reduction process was developed that incorporates a nonreactive sorptive sink and a reactive site, both of which are

ISSN:0730-7268    

DOI:10.1002/etc.5620061202

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractA large resource of unpublished technical data exists in the form of reports submitted by industry under the Toxic Substances Control Act (TSCA) to the U.S. Environmental Protection Agency. The TSCA Test Submissions (TSCATS) database was recently developed and made available to the public to allow computerized searching of test submissions according to specific chemical identity or type of study. Studies are categorized into three broad subject areas (health effects, environmental effects, environmental fate) and additional indexing terms are assigned from a controlled vocabulary describing the experimental protocol and certain observations of the test. Records from the on‐line database also contain reference information to assist in locating the source document, and to identify the submitting organization and reason for submission of the test dat

ISSN:0730-7268    

DOI:10.1002/etc.5620061203

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe anaerobic dechlorination of 4‐chlororesorcinol (4‐Cl‐Res) to resorcinol (1,3‐dihydroxybenzene) by fresh anaerobic digester sludge and by an enriched microbial culture was studied. Complete dechlorination of 50 ppm 4‐Cl‐Res in fresh sludge required about four weeks and occurred without a lag. An anaerobic community capable of degrading 4‐Cl‐Res was enriched with 4‐Cl‐Res as the substrate. Dechlorination of 4‐Cl‐Res by this enrichment occurred at a relatively low rate (0.3 μmol mg−1d−1) and after a long lag period (three weeks). Addition of yeast extract or trypticase markedly enhanced the rate of dechlorination. The rate increased from 0.3 μmol mg−1d−1in the unamended enrichment to 1.1 to 2.6 μmol mg−1d−1in cultures amended with 0.1% yeast extract or 0.1% trypticase. Also, the lag period was reduced from approximately three weeks to less than 2 d. The ability to stimulate reductive dechlorination is important because it demonstrates that this process can be enhanced by carbon additions that may lead to practical schemes for foste

ISSN:0730-7268    

DOI:10.1002/etc.5620061204

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe reported high mutagenic potency of 3‐chloro‐4‐(dichloromethyl)‐5‐hydroxy‐2(5H)‐furanone againstSalmonella typhimurium(TA100) was confirmed in the determined value of 6,300 net revertants/nmol. Partial inactivation of the furanone by Arochlor 1254‐induced rat liver homogenate fraction (S9) was observed. Inactivation by the nucleophiles hydroxide ion, SO2, S2O2/3−, pyrrolidine and glutathione, all in aqueous solutions, was determined and the results compared. Mutagenic reduction was observed for all of the nucleophiles but was most pronounced for glutathione. Inactivation by hydroxide ion was most sensitive in the pH range of 9 to 11, was associated with chloride ion formation and paralleled irreversible ultraviolet spectral change resulting in the loss of the 227 nm absorption maximum and the appearance of a new maximum at 255 nm. Neutral aqueous solutions of the furanone and glutathione were marked by two UV maxima, at 250 and 270 nm, and lacked the aldehydic1H‐NMR signal, which was observed in the spectrum of the neutral solution of the furanone alone and was attributed to the presence of its acyclic tautomeric form. Several other furanones were prepared. Their Ames mutagenicities and those of chlorine‐substituted intermediates obtained in the synthesis of the furanone were determined and compared, and then related to the reported mutagenicities of s

ISSN:0730-7268    

DOI:10.1002/etc.5620061205

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractDimethoate EC 40% and methomyl 90% WSP were applied under field conditions to follow up the decline of their residues on tomato and cabbage plants. The results indicate that the level of dimethoate and methomyl residues were found to be below tolerance level after 7 and 3 d from application, respectively. Dimethoate and methomyl residues also had significant effects on ascorbic acid contents in tomato fruits after 1 and 7 d for dimethoate, while the effect was after 3 and 10 d for methomyl. Dimethoate also showed significant effects on total soluble solids in tomato fruits presented until 14 d after pesticide application. Both dimethoate and methomyl had significant effect on both iron and magnesium content in tomato fruits and leaves and cabbage leaves during the 14 d.

ISSN:0730-7268    

DOI:10.1002/etc.5620061206

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractTo conduct toxicity tests, it is essential to include controls to ascertain the health of the test organisms. The common practice is to include negative controls in every test. That positive controls are not used is perhaps because there is no consensus about the reference toxicant. The objective of this study was to test chromate ion as a candidate for reference toxicant. Two aquatic phytotoxicity tests were performed: a millet root elongation test and a duckweed test.To the same test species, the Cr(VI) toxic effect was very consistent in repeated experiments. The toxic effects to millet were nearly identical in both deionized water and sewage effluent samples. The toxic effect to duckweed was also highly repeatable in 59 water samples from 18 sample stations. The results suggest that the Cr(VI) ion can be used as a general reference toxicant in river water, lake water or wastewater samples. The concentration‐effect relationships, however, are different, depending on the test organism

ISSN:0730-7268    

DOI:10.1002/etc.5620061207

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe nickel concentration of 1.0 mg/L in total form has been adopted as the indigenous aquatic life standard. The objective of this study was to test nickel toxicity to duckweed in water samples encompassing a wide variety of water quality. Fifty‐nine samples were collected from 18 stations: 10 in Illinois and 8 in neighboring states. Common duckweed,Lemna minor, was exposed to nickel for 96 h. Nickel exhibited the highest phytotoxicity to duckweed in water from the Hayes Creek and Horseshoe Lake stations, the two stations where water contained the lowest hardness, 37 to 78 mg/L as CaCO3. The IC50s for nickel were 0.36 and 0.21 mg/L, respectively. The other 16 stations, combined, showed a mean and standard deviation of 2.5 ± 0.83 mg/L. It is estimated that the nickel ion at a concentration of 1 mg/L can cause a 30% inhibition of duckweed growth in almost all surface waters, and a 70% inhibition in extremely soft wate

ISSN:0730-7268    

DOI:10.1002/etc.5620061208

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractSediment from Chesapeake Bay was fortified with naphthalene‐d8, diphenyl‐d10ether, di‐n‐octyl phthalate‐2,3,4,5‐d4,p,p‐DDT‐d8and chrysene‐d12to measure the bioaccumulation of sediment‐sorbed chemicals by baltic clams (Macoma balthica) and soft‐shell clams (Mya arenaria).Macomabioaccumulated the deuterated chemicals from sediment at measurable rates. Uptake transfer coefficients were derived from bioaccumulation, and forMacomathey ranged from 4.95 × 10−2h−1for diphenyl‐d10ether to 1.47 × 10−3h−1for chrysene‐d12. Transfer coefficients forMacomawere inversely related to the water solubilities of the sorbed chemicals.Myadid not show bioaccumulation of the sediment‐sorbed chemicals. Bedded sediments contaminated with trace organic chemicals may be a relevant source of exposure to toxicants in estuarine

ISSN:0730-7268    

DOI:10.1002/etc.5620061209

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractA comprehensive survey of a small Cambria County, Pennsylvania, watershed contaminated by a British Petroleum aviation kerosene leak was conducted from 9 November 1982 until 20 December 1983. The biological data showed evidence of a rapid recolonization process by benthic macroinvertebrates that began at the last two downstream stations shortly after the spill. The recovery at stations located immediately below the spill was delayed because few organisms for repopulation were present in the clean, upstream section and because a drought eliminated most of the biota in the immediate headwaters during 1983. Measurements of species diversity of benthic invertebrates showed that most of the stations in the contaminated sections recovered between June and October 1983. Short‐term in situ toxicity bioassays conducted with brook trout in April 1983 showed that the stream was again suitable for restocking with trout. In addition, a fish electroshocking program in May and October 1983 clearly demonstrated that the contaminated sections of the stream had recovered and again supported a diverse fish population, including trout and young‐of‐the‐year minnows and sunfish. The results of chemical analyses and biochemical oxygen demand measurements indicated that the water quality in the contaminated section recovered between 30 November and 14 December 1982.The major factors that accelerated the recolonization process in the contaminated watershed were (a) immediate and effective cleanup activities; (b) a plentiful source of unpolluted dilution water; (c) the drift of benthic organisms available for recolonization; and (d) the immigration of fish from the unpolluted sections of the wa

ISSN:0730-7268    

DOI:10.1002/etc.5620061210

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY