摘要:

AbstractThe fate of atrazine in sediment sampled from two agricultural watersheds in the Great Lakes basin of southern Ontario was studied in laboratory flask incubations of sediment slurry and enrichment cultures. Atrazine at an initial concentration of 10 mg/L disappeared within 15 d in sediment slurries incubated aerobically at 30°C. Because atrazine concentrations were stable in similarly incubated autoclaved slurry and the lag preceding atrazine degradation was abolished by repeated atrazine additions, it was concluded that the herbicide was biodegraded. Rapid atrazine degradation was found in concentrated suspended particulates and surface (0 to 10 cm) sediments, but not in sediments taken from a depth of 20 cm. Atrazine was not degraded under anaerobic or denitrifying conditions. Sediment and enrichment cultures converted [U‐ring‐14C]‐labeled atrazine to hydrophilic metabolites, tentatively identified as cyanuric acid and urea, and then to carbon d

ISSN:0730-7268    

DOI:10.1002/etc.5620140501

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA study was conducted on the effect of a nonionic surfactant on the efficiency of the integrated chemical‐biological treatment (ICBT) of polychlorinated biphenyls (PCBs) sorbed to the glass walls of the experimental vessels. The addition of surfactant associated with the chemical oxidation was proposed to overcome two limitations of biodegradation of hydrophobic compounds: adsorption to surfaces, and lack of solubility and thus availability to the microorganisms. Two14C‐labeled PCB congeners, 2‐chlorobiphenyl and 2,2′,4,4′‐tetrachlorobiphenyl, were used as the test compounds. The integrated chemical‐biological treatment consisted of sequential applications of Fenton's reagent (5% H2O2, 1 mM FeSO4) at pH 4.0 (with and without non‐ionic surfactant Novel II 1412‐60) and the inoculation with a mixed culture ofPseudomonassp., strain LB400, andAlcaligenes eutrophus, strain H850, at pH 8.0. The chemical treatment in the presence of surfactant affected the removal of the congeners bound to the glass surfaces of the experimental test systems. As indicated by high‐pressure liquid chromatography analysis, these PCBs were converted to unidentified soluble products that are hypothesized to be partial oxidation products. No parent test compounds were detectable in the system after chemical treatment with or without surfactant. The addition of the mixed culture of PCB‐degrading bacteria after completion of chemical treatment in the presence of surfactant resulted in the removal of approximately 45 % of 2‐chlorobiphenyl and 32% of 2,2′,4,4′‐tetrachlorobiphenyl in the form of14CO2.This compared to 29% and 23% without the addition of surfactant, respectively. We suggest that the combination of surfactant‐induced desorption and chemical oxidation would increase the availability of hydrophobic pollu

ISSN:0730-7268    

DOI:10.1002/etc.5620140502

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractBoth [14C]‐4‐nitrophenol (4‐NP) and [14C]‐3,4‐dichloroaniline (3,4‐DCA) were applied to laboratory sediment‐water systems; these were a sandy sediment (SED‐M), and a sediment with high clay/silt and organic carbon content (SED‐J). After sorption periods of 2 d (assay I) and 28 d (assay II) the water phases were replaced by fresh sample water. About 20/10% (3.9/3.9% of total applied 4‐NP in SED‐M/SED‐J) and 40/15% (8.5/6.2%; 3,4‐DCA) of the sediment‐associated radioactivity were initially (1 d of incubation) desorbed in assay I. The corresponding data of assay II amounted to 2/1% (0.9/0.7%; 4‐NP) and 3/2% (1.7/1.4%; 3,4‐DCA). No parent compounds were detected in the fresh‐water phases. The radioactivity released in assay I was readsorbed to the respective sediment. Remobilization distinctly reflected the preceding sorption process, and that regarding sediment properties and chemical features of 3,4‐DCA and 4‐NP. Fractionation of the nonextractable residues of 3,4‐DCA in SED‐J revealed that the xenobiotic was mainly attached to the insoluble humin fraction (55.8/53.8% after 7/28 d of incubation). Only minor amounts were associated with fulvic (14.3/12.7%) and humic acids (5.3/6.1%). Experiments using a clay fraction of SED‐J (<0.063 μm; SED‐J‐C) and bentonite (CM) demonstrated that 3,4‐DCA was primarily bound to the organic matter of SED‐J‐C. Concerning sorption of 3,4‐DCA, both SED‐J and SED‐J‐C behaved very alike; in contrast, CM showed a strikingly different pattern. Regarding “outdoor” situations, it may be concluded that 4‐NP is not translocated very far from th

ISSN:0730-7268    

DOI:10.1002/etc.5620140503

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe determined the ingestion and loss of the spores ofBacillus thuringiensisvar.israelensis (Bti)by a nontarget organismDaphnia magna.Daphnids were either not fed or fed during the exposure to the spores. The results showed that (a) the uptake rates with unfed and fed daphnids were approximately first‐order with respect to spore concentration, and the rate constants for unfed and fed daphnids were 5.5 × 10−5and 1.4 × 10−7L daphnid−1h−1, respectively, and (b) unfed and fed daphnids rapidly depurated the majority of the accumulated spores, and the depuration rate constants for unfed and fed daphnids were 0.13 and 0.15 h−1,

ISSN:0730-7268    

DOI:10.1002/etc.5620140504

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractInteractions between some phenolic compounds and macro‐constituents of synthetic seawater (Na+, K+, Ca2+, Mg2+, Cl−, and SO2−4), at 20, 35, and 45%0 salinity, have been investigated potentiometrically by using the [H]‐glass electrode. The formation constants of phenol,o‐ andp‐cresol,o‐ andp‐nitrophenol complexes with sodium, potassium, calcium, and magnesium ions have been determined in the ionic strength range 0 ≤I≤ 1 mol/L. A comparison between the apparent protonation constants of phenols determined in synthetic seawater, and those simulated by a suitable complex formation model, is discussed. The possibility of calculating, by simulation, the apparent protonation constants of some chlorophenolic compounds in synthetic seawat

ISSN:0730-7268    

DOI:10.1002/etc.5620140505

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractIt is relatively simple to determine the growth rate of a microorganism culture, minute‐by‐minute, by monitoring the CO2content of an air stream that has passed through the culture at a constant rate. Any change in the growth rate caused by the addition of a toxicant is readily detectable. This is the basis of a procedure for detecting sulfonylurea herbicides on vegetation. A freshwater alga (Chlorella pyrenoidosa sorokiniana)and baker's yeast (Saccharomyces cerevisiae)were the test organisms evaluated in this study. The alga was the more sensitive to sulfonylureas, and the effect of 0.01 μg of a sulfonylurea that had been simply leached from an apple leaf was evident in 15 min. Triazine herbicides inhibit theChlorellaeven more rapidly than the sulfonylu

ISSN:0730-7268    

DOI:10.1002/etc.5620140506

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA useful cadmium saturation method, the cadmium‐Chelex assay, is adopted and modified for quantification of metallothionein induction and protein cadmium saturation in midgut gland of cadmium‐exposed Roman snails (Helix pomatia).The assay is based on denaturation of nonmetallothionein, cadmium‐binding ligands; complete saturation of metallothionein by adding excess amounts of nonradioactive cadmium; and chelating of excessive amounts of cytosolic metal by the Chelex‐100 cation exchange resin. After short‐term cadmium feeding, snails quickly responded by showing rising metallothionein levels, protein concentrations in the midgut gland increasing from about 300 μg/g tissue (wet weight) to 750 μg/g within a period of 2 d. At the same time cadmium loading of protein rose form 20% in control snails to 50% saturation in exposed individuals. After long‐term cadmium exposure, maximal metallothionein concentrations of about 1,000 μg/g tissue (wet weight) and a relative metallothionein cadmium saturation of 70% were reached in midgut glands of exposed snails. It is proposed that metallothionein quantification inH. pomatiamight be used as a tool for biomarker studies in three ways. First, the slope of metallothionein induction might be used as a biomarker for incipient cadmium exposure and for the responsiveness of an invertebrate to metal exposure stress. Second, the steady‐state level of metallothionein concentration in the midgut gland ofH. pomatiamight serve as an integrating biomarker reflecting single or repeated exposure events occurring over a prolonged period of time. Third, the percentage cadmium saturation of metallothionein could be utilized as a biomarker indicating if and by how much the detoxification capacity ofH. pomatiais becoming exhausted due to elevated

ISSN:0730-7268    

DOI:10.1002/etc.5620140507

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractDensities, food habits, and physical condition of white‐footed mice(Peromyscus leucopus)were examined on 10 Dimilinr̀‐treated and 10 untreated areas in 1985 and 1986. Estimates of mouse density did not differ significantly (p>0.05) between treated and untreated areas. However, juvenile/adult female ratios on untreated areas were significantly higher (p<0.05) than those on treated areas. Mice on treated areas consumed less lepidopteran prey than did mice on untreated areas (p0.05) between treated and untreated a

ISSN:0730-7268    

DOI:10.1002/etc.5620140508

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractConcentrations of lipophilic contaminants in biota are frequently corrected for variation in tissue lipid content. Usually, this correction is accomplished by dividing tissue contaminant concentration by lipid concentration to form lipid‐normalized data. This ratio‐based approach is satisfactory when contaminant concentration varies in direct proportion to lipid content. However, when such a relationship does not exist, erroneous conclusions may be reached. Recent research has emphasized the potential shortcomings of the use of ratio variables. We demonstrate the importance of considering these shortcomings when lipid‐normalizing data. Three examples are presented, and an alternative approach based upon the use of analysis of covariance (ANCOVA) is sugg

ISSN:0730-7268    

DOI:10.1002/etc.5620140509

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe literature suggests that acid deposition may lead to increased mercury (Hg) contamination of fish. Employing published empirical relationships, we have estimated the change in associated Hg contamination with an increase in sulphate deposition from 0.25 to 1.25 g sulfur/m2/year. In seepage lakes, one can predict that Hg in walleye from these lakes, and subsequent human exposure due to consumption of these fish, would be elevated at the higher rate of sulphate deposition. However, for drainage lakes, increasing acidic deposition was predicted to reduce Hg accumulation in lake trout and northern pike. Subsequent human exposure to Hg due to consumption of these species from drainage lakes was therefore also predicted to be lower at the higher rate of acidic deposition. We concluded that the hypothesis that acidic deposition increases mercury (Hg) contamination in fish, and thereby mercury exposure in humans via fish consumption, is only true for acidic deposition onto seepage lakes.

ISSN:0730-7268    

DOI:10.1002/etc.5620140510

出版商:Wiley Periodicals, Inc.    

年代:1995

数据来源: WILEY