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The photochemical degradation of the herbicide isoproturon in aqueous and non-aqueous solutions and in soils has been investigated. Four new photometabolites were formed in non-aqueous solution and three in soil. These were characterised by spectroscopic methods and identified by comparison with authentic synthetic samples such as 3-(4-isopropylphenyl)-1-methylurea; 3-(4-isopropylphenyl)urea; 4,4′-diisopropylazobenzene and 4,4′-diisopropylazoxybenzene. The pathway of formation of these photo products is depicted. 相似文献
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Dissipation of dithiopyr in soil was monitored after application to wheat crop as pre- or post-emergence applications at two rates, viz 100 and 200 g AI ha(-1). The level of dithiopyr in the soil was assessed by gas chromatography, and its disappearence was found to follow a first-order decay curve irrespective of rate or method of application. The half-life in soil ranged between 17.3 and 25.0 days and residues at harvest (150 days after application) ranged between 4.0 and 8.8% of amounts applied. Investigation of microbial degradation of dithiopyr was conducted in minimal salt and Czapek Dox media in which 80% of the compound degraded within 15 days. Residues were not detected in wheat grain at harvest. 相似文献
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Effects of repeated metolachlor applications on its persistence in field soil and degradation kinetics in mixed microbial cultures 总被引：1，自引：0，他引：1
The persistence of metolachlor, a soil-applied herbicide, was studied under field conditions involving repeated herbicide
applications. The test field received four applications of metolachlor over an 8-month period, which included two cropping
seasons. There was a trend for more rapid rates of degradation with increasing numbers of previous treatments, with fifty
percent dissipation time (DT50) of metolachlor declining from 18 days in the first spray to 2.5 days in the fourth spray. An effort was made to isolate
the microbial population which had become acclimated to the herbicide from this field soil. A fungal community isolated from
this soil showed the capacity to degrade up to 99.6% of the metolachlor within a span of 20 days. The bacterial community
isolated could also degrade up to 81.5% of the metolachlor. Hence, this study clearly indicated that repeated applications
of metolachlor to soil resulted in the generation of an adapted microbial population with an enhanced ability to degrade the
applied herbicide.
Received: 13 November 1998 相似文献
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The organophosphorus insecticide, chlorpyrifos, has been widely applied in agriculture; in veterinary, against household pests;
and in subterranean termite control. Due to its slow rate of degradation in soil, it can persist for extended periods in soil
with a significant threat to environment and public health. The mixed and pure fungi were isolated from three soils by enrichment
technique. The enriched mixed fungal cultures were capable of biodegrading chlorpyrifos (300 mg L−1) when cultivated in Czapek Dox medium. The identified pure fungal strain, Acremonium sp., utilized chlorpyrifos as a source of carbon and nitrogen. The highest chlorpyrifos degradation (83.9%) by Acremonium sp. strain GFRC-1 was found when cultivated in the nutrient medium with full nutrients. Desdiethyl chlorpyrifos was detected
as a major biodegradation product of chlorpyrifos. The isolated fungal strain will be used for developing bioremediation strategy
for chlorpyrifos-polluted soils. 相似文献
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The effect of a mixed fungal culture on the degradation of the herbicide metolachlor in soil was evaluated. Metolachlor was found to degrade up to 92% and 87% after 20 days in sterile and nonsterile soils respectively, when inoculated with a mixed culture of Aspergillus flavus and Aspergillus terricola and treated with 20 g g–1 metolachlor. When the soil was treated at 50 g g–1 level, 84% of the added herbicide degraded in inoculated sterile soil and 80% in nonsterile soil. The half-lives of metolachlor were found to be 5 and 4 times faster at the 20 and 50 g g–1 levels, respectively, in the presence of the mixed fungal culture. In treated soils, four metabolites could be identified by RP-HPLC. 相似文献
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Seven impurities, namely, isopropylaniline (III), isopropylacetanilide (V), isopropylchloroacetanilide (VII), oxoanalogue (VIII), dithiodimer (IX), monothiodimer (X), and mercaptoacetanilide (XI), have been identified from technical anilofos. The quantification of each impurity was carried out by comparison with authentic samples of known concentration by GC and HPLC. The structure of authentic samples (synthesized and isolated) was established on the basis of NMR, IR, and MS spectral data. Bioassay of all the detected impurities along with three possible contaminants was carried out on transplanted rice under laboratory conditions. The oxo compound (VIII) was found to have an inhibitory effect on transplanted rice at 1 microg/g of soil. 相似文献