ISSN:0730-7268    

DOI:10.1002/etc.5620121101

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe fate of atrazine and one of its degradation products deisopropylatrazine has been investigated using radiotracers under laboratory conditions. The metabolic route and rate were investigated under saturated and unsaturated conditions, with samples of soil taken from four depths down to 120 cm. The major degradation products identified from [14C]atrazine and [14C]deisopro‐pylatrazine treatments were deethylatrazine and didealkylatrazine, respectively. The detected minor degradation products were hydroxyatrazine, deethylhydroxyatrazine, and deisopropylhydroxyatra‐zine. Under unsaturated conditions atrazine and deisopropylatrazine were least persistent in the top 30 cm, and their persistence increased with increase in depth. The half‐life of atrazine under unsaturated conditions increased with depth and ranged from 41 to 231 d for the studied depths, whereas the half‐life of deisopropylatrazine ranged from 32 to 173 d. Deisopropylatrazine was more susceptible to mineralization than atrazine, and the amount of mineralization decreased with increase in depth. Bound residues were formed to a greater extent in surface soils. Under saturated conditions at the 90‐ to 120‐cm depth, the half‐life of atrazine was 87 d. Deisopropylatrazine was less persistent in saturated soil than in unsaturated soil at the 90‐ to 120‐cm depth, with a half‐life of 58 and 173 d, respectively. The increased degradability of deisopropylatrazine as compared with atrazine and the decreased persistence of deisopropylatrazine under saturated soil conditions provides a logical explanation for its relatively low concentrations in ground water as com

ISSN:0730-7268    

DOI:10.1002/etc.5620121102

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe movement and degradation of [14C]‐atrazine were studied in undisturbed soil columns (15 × 60 cm) taken manually from a field with no previous pesticide history. The experiment was conducted indoors under controlled temperature conditions. Three weeks after application of [14C]‐atrazine (2.2 kg a.i. per hectare) to the soil surface, the columns were leached at weekly intervals for 12 weeks. Approximately 1.2% of the applied14C was recovered in the leachate over the 12‐week period, which corresponds to an atrazine (plus degradation products) concentration of 7.6 μg/L. On completion of the last leaching event, the columns were cut into 10‐cm increments and analyzed for [14C]‐atrazine and degradation products. Seventy‐seven percent of the14C applied to soil columns remained in the upper 10 cm and included primarily atrazine (9%) and soil‐bound residues (57%). Deethylatrazine was the predominant degradation product in the top 10 cm (3.6%). Other degradation products were found in the top 10 cm at relative concentrations of deisopropylatra‐zine>hydroxyatrazine>didealkylatrazine>deethylhydroxyatrazine>deisopropylhydroxyatra‐zine. Uncharacterized polar metabolites in the top 10 cm accounted for 6% of the applied14C. Atrazine, deethylatrazine, and deisopropylatrazine were found at all depths. In addition, didealkylatrazine was detected to the 50‐cm depth, hydroxyatrazine to the 30‐cm depth, and deethylhydroxyatra

ISSN:0730-7268    

DOI:10.1002/etc.5620121103

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractDrift of the pesticideBacillus thuringiensisBerliner var.kurstaki(Bt) was measured downwind from a gypsy moth (Lymantria dispar L.) treatment block in mountain terrain. The study was conducted in conjunction with a project to eradicate the moth along the Wasatch mountain range of Utah. Objectives of the study were to quantitate drift, to evaluate drift sampling methods, and to compare FSCBG (Forest Service Cramer‐Barry‐Grim) computer model predictions to field measurements of Bt based on colony‐forming units. The treatment block was sprayed by helicopter three times, within a 12‐d period during June 1991, which provided a study of three replicates. During each spray, downslope drainage winds carried the spray over an array of samplers that extended 3,150 m downwind. The FSCBG dispersion model, exercised after the treatments, used meteorological inputs measured during the treatments to predict spray deposition and airborne dosage of Bt. Results of the study demonstrated a correlation among dosage, deposition and total flux samplers; a potential of Bt drift of at least 3,150 m; and FSCBG model predictions that generally followed the field recove

ISSN:0730-7268    

DOI:10.1002/etc.5620121104

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractA study was conducted to examine the role of two processes, partitioning of PCBs between sediment and biota and food‐web transport, in determining the concentration of PCB congeners in the biota of seven lakes. Biota PCB concentration (lipid)‐to‐sediment PCB concentration (organic carbon), or BSF, ratios were calculated as markers of the partitioning of PCBs between biota and sediment, and biota PCB concentration (lipid)‐to‐zooplankton PCB concentration (lipid), or BAF, ratios were calculated as markers of the transport of PCBs through food webs. The lakes ranged from a shallow, well‐mixed lake with a historic input of Aroclor technical mixtures to deeper, oligotrophic systems in which atmospheric deposition was the only known source. BSF ratios ranged from approximately one in cyprinids and zooplankton in all lakes to 30 in yellow perch in one lake. A significant correlation between lake maximum depth and the combined BSF ratios for all biota indicated that PCBs were generally more available for accumulation in the shallower lakes, regardless of the PCB source. Principal component analysis (PCA) showed that the biota in the shallower lakes had higher ratios of higher chlorinated congeners, suggesting that predictions of equal concentrations of hydrophobic contaminants on a lipid basis in sediment and lower trophic levels may significantly underestimate the accumulation of very hydrophobic compounds in the organisms of some lake systems. BAF ratios ranged from approximately one in the lower trophic levels to approximately 10 in lake trout. A significant relationship between the BAF ratio and lake maximum depth for combined data for all biota, and particularly for smallmouth bass (Micropterus dolomieuiLacé‐pède), probably indicated the increasing role of food‐web transport of PCBs in deeper lakes. PC analysis of BAF ratios for individual congeners characterized lake trout (Salvelinus namaycushWal‐baum) and yellow perch (Perca flavescens) on the basis of higher ratios for the majority of congeners but also split the two species on the basis of higher ratios of lower chlorinated congeners in perch and highly chlorinated congeners in lake trout. The separation of the two species collected from the same lakes was attributed to their posit

ISSN:0730-7268    

DOI:10.1002/etc.5620121105

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractOxidation of 2,4,6‐trichlorophenol (TCP) by layered manganese oxides (Na and Co‐buserite) in dilute acidified aqueous suspension gives 2,6‐dichloro‐p‐benzoquinone as a major product. This compound is likely to further polymerize and become incorporated into humuslike materials. The oxidation rate was higher at lower pH and higher on Na‐buserite compared to Co‐buserite. TCP reacted at a faster rate than unsubstituted phenol at pH 3 and 5.5, which is explained by (a) the lower half‐wave potential of TCP compared to phenol; (b) a stronger bond dipole associated with the electronegative halogen, favoring an addition step in nucleophilic substitution; and (c) easier deprona‐tion of TCP at the manganese oxide‐water interface due to its lower pKa. IR spectroscopy shows that TCP adsorbs in deprotonated form on the surface of manganese oxide, and it cannot be washed from the surface by water. Nucleophilic attack by addition‐elimination is suggested as a mechanism of TCP dechlor

ISSN:0730-7268    

DOI:10.1002/etc.5620121106

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractSome monomeric and dimeric oxidation products of para‐ and/or ortho‐chlorinated phenols in dilute (1 mmol/L phenol), acidified, aqueous suspensions of manganese oxide (Na‐buserite) were identified by MS, Fourier‐transform IR spectroscopy and UV/visible spectroscopy. The para‐chlorinated phenols (4‐chlorophenol, 2,4‐dichlorophenol, 2,4,6‐trichlorophenol, 4‐chloro‐2‐methylphenol) gave correspondingp‐benzoquinones (benzoquinone, 2‐chlorobenzoquinone, 2,6‐dichlorobenzoquinone, 2‐methylbenzoquinone) as the detectable water‐soluble oxidation products. Dimeric products were present in the extracts obtained by washing the oxide with methylene chloride. Michael addition of phenolate to quinone seems to be the predominant mode of coupling. Chlorinated phenols without chlorine in the para‐position (2‐chlorophenol, 2,6‐dichlorophenol) were more difficult to oxidize and afforded diphenoquinones as the only detectable water‐soluble products. For all studied phenols, with the exception of 2,4,6‐trichlorophenol, the amount of water‐soluble products accounts only for a small fraction of oxidized phenol. The quinone and diphenoquinone products readily c

ISSN:0730-7268    

DOI:10.1002/etc.5620121107

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe acclimation or adaptation of microorganisms to organic chemicals is an important factor influencing both the rate and the extent of biodegradation. In this study two acclimation procedures were evaluated in terms of their effectiveness in enhancing biodegradation, their relative ease of use in the laboratory, and the implications for biodegradability testing. In the single‐flask procedure, microorganisms were acclimated for 2 to 7 d in a single acclimation flask at constant or increasing concentrations of the test chemical without transfer of microorganisms. In the second procedure, the enrichment procedure, microorganisms were acclimated in a series of flasks over a 21‐d period by making adaptive transfers to increasing concentrations of the test chemical. Acclimated microorganisms from each procedure were used as the source of inoculum for subsequent biodegradation tests in which carbon dioxide evolution was measured. Six chemicals were tested: quinoline,p‐nitrophenol,N‐methylaniline,N,N‐dimethylaniline, acrylonitrile, and 2,2,4‐trimethyl‐1,3‐pentanediol monoisobutyrate. Microorganisms acclimated in the single‐flask procedure were much more effective than those acclimated in the enrichment procedure in degrading the test chemicals. The single‐flask procedure is more convenient to use, and it permits monitoring of the time needed for acclimation. The results from these studies have implications for the methodology used in biodegradation test systems and suggest caution before adopting a multiple‐flask, enrichment acclimation procedure before the performance of standardized tests for aer

ISSN:0730-7268    

DOI:10.1002/etc.5620121108

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractAqueous solubilities (S) and 1‐octanol/water partition coefficients (Kow) of four PCBs—4‐chlorobiphenyl, 2,4,6‐trichlorobiphenyl, 2,3,4,5‐tetrachlorobiphenyl, and 2,2′,4,4′,6,6′‐hexachlo‐robiphenyl—were determined both individually and in pairs, using a generator‐column technique, to investigate the effect of cosolutes onSandKow, No statistical differences betweenSandKowmeasured individually and in pairs were observed for the four PCBs in 20 out of 24 cases. In the other four casesSorKowmeasured in the presence of a cosolute was only slightly different from tha

ISSN:0730-7268    

DOI:10.1002/etc.5620121109

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractGas sparging was conducted in lake enclosures previously treated with [4,6‐3H]‐2,3,7,8‐tetrachlorodibenzofuran (TCDF) to determine the fugacity or dissolved concentration of this hydrophobic contaminant under field conditions. Using a Henry's law constant for TCDF of 1.7 ± 0.8 Pa.m3/mol, measured experimentally by gas sparging, apparent dissolved TCDF concentrations of 7 to 22 pg/L were determined. These results were 100 times greater than concentrations of TCDF obtained by extraction of water samples from the same enclosures with dichloromethane. TCDF was found to be highly associated with naturally occurring particles in the water column, with 40% of sorbed TCDF associated with the 0.1‐ to 3‐μm size fraction. The results are interpreted in light of previous reports that indicate that bubbles are effective scavengers of bacteria and particulates in natural waters, transporting these solids across the water/air interface as bubbles burst at the water surface. In the laboratory addition of a yeast suspension increased the amount of TCDF sparged from aqueous solutions, confirming that particle‐mediated movement of highly sorbed contaminants can influence apparent water concentrations measured by gas sparging of n

ISSN:0730-7268    

DOI:10.1002/etc.5620121110

出版商:Wiley Periodicals, Inc.    

年代:1993

数据来源: WILEY