ISSN:0730-7268    

DOI:10.1002/etc.5620100501

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe mobility and decomposition of the herbicide clopyralid (3,6‐dichloro‐2‐pyridinecar‐boxylic acid) were studied under field conditions in a sandy soil and a clay soil. Leachate was collected in lysimeters with undisturbed soil (sand) and in tile‐drained plots (clay). Soil samples were also collected down to 1 m depth in both soils to characterize the temporal depth distribution of clopyralid in the profiles. The herbicide was applied at two rates, i.e., 120 and 240 g acid equivalents (a.e.)/ha, representing normal and double doses of the compound for sugar beets and oilseed rape. Some lysimeters received supplementary watering. Concentrations of clopyralid above the detection limit {0.4μg/L}, i.e., 0.5 (normal dose) and 6 μg/L (double dose) were found in only two drainage samples from the clay soil. Both samples were collected simultaneously approximately two months after the herbicide application, by which time less than 1 mm of drainage had been collected. The overwhelming part of applied clopyralid remained in the topsoil at both sites. Four months after spraying, no clopyralid was detectable (<2 μg/kg dry soil)

ISSN:0730-7268    

DOI:10.1002/etc.5620100502

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractMobility and persistence of metribuzin (Lexone DF) and its metabolites (deaminated, DA; diketo, DK; deaminated‐diketo, DADK) were studied using 75‐cm × 15‐cm field lysimeters packed with Plainfield sand, and subjected to two moisture regimes (rainfall, supplementary watering). Atrazine was applied to all lysimeters as an internal reference. Each lysimeter set consisted of 24 lysimeters, divided into two moisture treatments of six pairs each. Effluent was monitored for metribuzin, DA, DK, DADK, atrazine and desethylatrazine. Selected core pairs were sectioned (7 × 10 cm) and analyzed to determine mobility and persistence for each chemical at weeks 1, 2, 4, 8, 12, and 21. No chemicals moved more than 30 cm, nor were they detected in the effluent of cores receiving rainfall. In cores receiving supplementary watering, substantial amounts of metribuzin moved more than 30 cm by week 2 and eluted on 21 occasions throughout the study. The DADK and DK were much more mobile than metribuzin in the lysimeters, eluting more frequently than metribuzin. Metribuzin and metabolites were considerably more mobile than either atrazine or desethylatrazine in Plainfield sand. Metribuzin disappearance closely followed first‐order kinetics witht1/2values of 3.08 and 2.04 weeks, respectively, for the rainfall and supplementary watering treatments. The primary degradation pathway for metribuzin was through the DK intermediate rather than the DA int

ISSN:0730-7268    

DOI:10.1002/etc.5620100503

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe inhibitory effects on growth and phosphate uptake by two toxicants, 3,5‐dichloro‐phenol and potassium dichromate, were studied in batch culture experiments with the freshwater green algaSelenastrum capricornutum. The EC50 figures for inhibition of phosphate uptake were considerably smaller than corresponding figures for growth inhibition, but threshold toxicities did not differ as much. Toxic inhibition of phosphate uptake may potentially influence interspecies competition among phytoplank

ISSN:0730-7268    

DOI:10.1002/etc.5620100504

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA strategy for systematic analysis and priority ranking of chemicals was applied to a class of 58 saturated halogenated aliphatics. The training set, selected by statistical design, was subjected to biological testing in an assay (the DNA precipitation assay) estimating DNA damage in V79 Chinese hamster cells. The obtained genotoxicity data were modeled by construction of two multivariate quantitative structure‐activity relationships (QSARs). To experimentally validate the two derived QSAR models, a validation set of chemicals was chosen (also according to statistical design). Predictions were made for the validation set compounds, and they were found to compare well with the observed data. Thus, the two QSARs were utilized to predict the genotoxicity of 36 nontested compounds belonging to the examined class. In addition, it was found that the genotoxicity data required a multitude of chemical and structural descriptors in order to be modelable, and that logPin particular was an informative descriptor variabl

ISSN:0730-7268    

DOI:10.1002/etc.5620100505

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractEngineered bacterial strains have been developed for several environmental uses, including bioremediation and application as biopesticides. Previous in vivo work in this laboratory examined the colonization and competition potential ofPseudomonasspp., isolated from a commercial product for PCB degradation with the intestinal flora of CD‐1 mice. In the present study, the same pseudomonads and two additionalEscherichia colistrains were evaluated by an in vitro tier testing approach developed to screen environmentally relevant microorganisms for their ability to colonize the mammalian intestinal tract and compete with the normal intestinal tract flora. In the initial tier, the competitor strains were tested for their ability to survive in anaerobic pure culture. Next, they were cultured anaerobically in the presence of mouse fecal microbiota. Finally, serial transfers were performed to monitor the survival and competition potential of each strain with the fecal microbiota. All of the tested strains survived for 48 h in pure culture, and all survived for 24 h in culture with the mouse fecal microbiota.Escherichia colistrains survived serial transfer through five cultures, although in declining numbers. EnvironmentalPseudomonasspp. survived transfer through three cultures but were not detected after four transfers. No effects of the competitor strains on the fecal microbiota were found. This in vitro system eventually will be used with human fecal microbiota. The potential consequences of human exposure to environmentally released microorganisms can then be extrapolated by comparison of human in vitro results with rodent in vitro and in vivo results in a parallelogram approac

ISSN:0730-7268    

DOI:10.1002/etc.5620100506

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe sorption and degradation of several benzidine‐based dyes were studied in sedimentwater systems. Studies in resaturated sediment demonstrated that sorption was strongly dependent on pH and the nature and concentration of the inorganic salt in solution. Degradation of the dyes in anaerobic pond sediment followed pseudo‐first‐order kinetics with half‐lives ranging from 2 to 16 d. Product studies indicated that the amount of recovered benzidine accounted for only 2 to 5% of lost Direct Red 28. Studies in pH‐amended pond sediment demonstrated that degradation is inhibited when the dyes are strongly sorbed to the

ISSN:0730-7268    

DOI:10.1002/etc.5620100507

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe fate of triclopyr butoxyethyl ester was investigated following direct aerial application to a boreal forest stream. The average deposit monitored at the stream surface was 3.67 kg acid equivalent (a.e.)/ha (range = 3.35‐3.99 kg a.e./ha). Residues of triclopyr as the butoxyethyl ester (TBEE), triclopyr acid (TRI) and pyridinol metabolite (PYR) were determined in various aquatic substrates. Streamwater residues of TBEE resulting from direct overspray were characterized by instantaneous maxima (0.23‐0.35 mg/L). A series of diminishing pulses of chemical associated with inputs upstream of the sampling site were observed. Average concentrations of TBEE in stream water ranged from 0.05 to 0.11 mg/L during the first 12 to 14 h post‐application and declined to levels below the limits of quantification (0.001 mg/L) within 72 h post‐application. Transient residues of TRI were observed in stream water, with a maximum concentration (0.14 mg/L) 6 h post‐application. The PYR residues did not exceed limits of quantification (0.05 mg/L) in any sample. Results indicate that natural dissipation mechanisms reduce both the period and the concentrations to which aquatic organisms would b

ISSN:0730-7268    

DOI:10.1002/etc.5620100508

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractTwo hypothetical supercooled liquid (HSL) solubility estimation methods are evaluated for 11 solid polynuclear aromatic hydrocarbons (PAHs). The HSL solubility is required to estimate the aqueous solubility of solids such as PAHs when they are part of a liquid hydrocarbon mixture. Aqueous solubility experimental data for binary and multicomponent liquid hydrocarbon mixtures containing PAHs were used to evaluate the HSL solubility estimation methods. An HSL solubility estimation method requiring only the component's pure compound solubility and melting point proved to be adequate for most environmental applications.

ISSN:0730-7268    

DOI:10.1002/etc.5620100509

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe toxicity of Cu++, Ni++, and linear alkylbenzene sulfonate to the bacterioplankton in the Rhóne River plume (Mediterranean Sea) was assessed by [3H]thymidine incorporation into trichloroacetic acid‐insoluble material. This method proved useful to evaluate the toxic effect of three common pollutants to the natural bacterial population in a system with permanent mixtures of fresh and sea water. An important variability in the toxicity has been detected irrespective of bacterial density or activity. The variations in toxicity were associated with the changes of salinity, particulate matter, and nutrients in the river plu

ISSN:0730-7268    

DOI:10.1002/etc.5620100510

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY