The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Shu Cai - One of the best experts on this subject based on the ideXlab platform.
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biodegradation of Chloroacetamide herbicides by paracoccus sp fly 8 in vitro
Journal of Agricultural and Food Chemistry, 2011Co-Authors: Jun Zhang, Jinwei Zheng, Bin Liang, Chenghong Wang, Shu CaiAbstract:A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six Chloroacetamide herbicides as carbo...
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Biodegradation of Chloroacetamide herbicides by Paracoccus sp. FLY-8 in vitro.
Journal of agricultural and food chemistry, 2011Co-Authors: Jun Zhang, Jinwei Zheng, Bin Liang, Chenghong Wang, Shu CaiAbstract:A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six Chloroacetamide herbicides as carbon sources for growth, and the degradation rates followed the order alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor. The influence of molecular structure of the Chloroacetamide herbicides on the microbial degradation rate was first analyzed; the results indicated that the substitutions of alkoxymethyl side chain with alkoxyethyl side chain greatly reduced the degradation efficiencies; the length of amide nitrogen’s alkoxymethyl significantly affected the biodegradability of these herbicides: the longer the alkyl was, the slower the degradation efficiencies occurred. The phenyl alkyl substituents have no obvious influence on the degradation efficiency. The pathway of butachlor complete mineralization was elucidated on the basis of the results of metabolite identification and enzyme as...
Henrik Rasmus Andersen - One of the best experts on this subject based on the ideXlab platform.
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Identification and ecotoxicity of degradation products of Chloroacetamide herbicides from UV-treatment of water.
Science of the Total Environment, 2013Co-Authors: Yasmine Souissi, Stephane Bouchonnet, Sophie Bourcier, Kresten Ole Kusk, Michel Sablier, Henrik Rasmus AndersenAbstract:The widespread occurrence of chlorinated herbicides and their degradation products in the aquatic environment raises health and environmental concerns. As a consequence pesticides, and to a lesser degree their degradation products, are monitored by authorities both in surface waters and drinking waters. In this study the formation of degradation products from ultraviolet (UV) treatment of the three Chloroacetamide herbicides acetochlor, alachlor and metolachlor and their biological effects were investigated. UV treatment is mainly used for disinfection in water and wastewater treatments. First, the chemical structures of the main UV-degradation products were identified using gas chromatography coupled with mass spectrometry and liquid chromatography-mass spectrometry. The main transformation reactions were dechlorination, mono- and multi-hydroxylation and cyclizations. The ecotoxicity of the mixed photoproducts formed by UV-treatment until 90% of the original pesticide was converted was compared to the toxicity of Chloroacetamides using the green alga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the marine bacteria Vibrio fischeri as test organisms. UV-treatment of alachlor and metolachlor increased the toxicity compared to the parent compounds while an equal toxicity was found for photolysis products of acetochlor. This suggests that toxic photodegradation products are generated from Chloroacetamides under UV-treatment. An important perspective of this finding is that the photolysis products are at least as toxic as the parent compounds. © 2013 Elsevier B.V. All rights reserved.
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Identification and ecotoxicity of degradation products of Chloroacetamide herbicides from UV-treatment of water.
Science of The Total Environment, 2013Co-Authors: Yasmine Souissi, Stephane Bouchonnet, Sophie Bourcier, Kresten Ole Kusk, Michel Sablier, Henrik Rasmus AndersenAbstract:The widespread occurrence of chlorinated herbicides and their degradation products in the aquatic environment raises health and environmental concerns. As a consequence pesticides, and to a lesser degree their degradation products, are monitored by authorities both in surface waters and drinking waters. In this study the formation of degradation products from ultraviolet (UV) treatment of the three Chloroacetamide herbicides acetochlor, alachlor and metolachlor and their biological effects were investigated. UV treatment is mainly used for disinfection in water and wastewater treatments. First, the chemical structures of the main UV-degradation products were identified using gas chromatography coupled with mass spectrometry and liquid chromatography–mass spectrometry. The main transformation reactions were dechlorination, mono- and multi-hydroxylation and cyclizations. The ecotoxicity of the mixed photoproducts formed by UV-treatment until 90% of the original pesticide was converted was compared to the toxicity of Chloroacetamides using the green alga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the marine bacteria Vibrio fischeri as test organisms. UV-treatment of alachlor and metolachlor increased the toxicity compared to the parent compounds while an equal toxicity was found for photolysis products of acetochlor. This suggests that toxic photodegradation products are generated from Chloroacetamides under UV-treatment. An important perspective of this finding is that the photolysis products are at least as toxic as the parent compounds.
Jun Zhang - One of the best experts on this subject based on the ideXlab platform.
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biodegradation of Chloroacetamide herbicides by paracoccus sp fly 8 in vitro
Journal of Agricultural and Food Chemistry, 2011Co-Authors: Jun Zhang, Jinwei Zheng, Bin Liang, Chenghong Wang, Shu CaiAbstract:A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six Chloroacetamide herbicides as carbo...
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Biodegradation of Chloroacetamide herbicides by Paracoccus sp. FLY-8 in vitro.
Journal of agricultural and food chemistry, 2011Co-Authors: Jun Zhang, Jinwei Zheng, Bin Liang, Chenghong Wang, Shu CaiAbstract:A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six Chloroacetamide herbicides as carbon sources for growth, and the degradation rates followed the order alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor. The influence of molecular structure of the Chloroacetamide herbicides on the microbial degradation rate was first analyzed; the results indicated that the substitutions of alkoxymethyl side chain with alkoxyethyl side chain greatly reduced the degradation efficiencies; the length of amide nitrogen’s alkoxymethyl significantly affected the biodegradability of these herbicides: the longer the alkyl was, the slower the degradation efficiencies occurred. The phenyl alkyl substituents have no obvious influence on the degradation efficiency. The pathway of butachlor complete mineralization was elucidated on the basis of the results of metabolite identification and enzyme as...
A. Lynn Roberts - One of the best experts on this subject based on the ideXlab platform.
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Neutral degradates of Chloroacetamide herbicides: Occurrence in drinking water and removal during conventional water treatment
Water research, 2008Co-Authors: Michelle L. Hladik, Edward J. Bouwer, A. Lynn RobertsAbstract:Abstract Treated drinking water samples from 12 water utilities in the Midwestern United States were collected during Fall 2003 and Spring 2004 and were analyzed for selected neutral degradates of Chloroacetamide herbicides, along with related compounds. Target analytes included 20 neutral Chloroacetamide degradates, six ionic Chloroacetamide degradates, four parent Chloroacetamide herbicides, three triazine herbicides, and two neutral triazine degradates. In the fall samples, 17 of 20 neutral Chloroacetamide degradates were detected in the finished drinking water, while 19 of 20 neutral Chloroacetamide degradates were detected in the spring. Median concentrations for the neutral Chloroacetamide degradates were ∼2–60 ng/L during both sampling periods. Concentrations measured in the fall samples of treated water were nearly the same as those measured in source waters, despite the variety of treatment trains employed. Significant removals (average of 40% for all compounds) were only found in the spring samples at those utilities that employed activated carbon.
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Neutral Chloroacetamide herbicide degradates and related compounds in Midwestern United States drinking water sources.
The Science of the total environment, 2007Co-Authors: Michelle L. Hladik, Edward J. Bouwer, A. Lynn RobertsAbstract:Abstract Recent studies have revealed the presence of neutral degradates of Chloroacetamide herbicides in the Chesapeake Bay at concentrations greatly in excess of the parent compounds. As some degradates are being considered for regulation in drinking water, exposure of human populations to such micropollutants is of interest. Here we report the results of a survey of source waters used by 12 drinking water utilities in the Midwestern United States. Analytes included 20 neutral and six ionic Chloroacetamide degradates, four parent Chloroacetamide herbicides, three triazine herbicides, and two triazine degradates. Samples were collected during Fall 2003 and Spring 2004. In the fall samples, 16 of 20 neutral Chloroacetamide degradates were detected, while 18 of 20 neutral Chloroacetamide degradates were detected in the spring samples. Concentrations of most parent Chloroacetamides and neutral degradates were somewhat to substantially higher in the spring than in the fall, with median concentrations of ∼ 10–100 ng/L. Groundwater sources tended to have lower concentrations of parents and neutral degradates than surface water sources in the fall, although concentrations of parents and degradates in groundwater were similar to those in surface water in the spring.
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Acid- and base-catalyzed hydrolysis of Chloroacetamide herbicides.
Journal of agricultural and food chemistry, 2006Co-Authors: Daniel L. Carlson, Khoi D. Than, A. Lynn RobertsAbstract:Despite the prevalence of Chloroacetamides as herbicides, little is known about the rates or products of acid- or base-catalyzed hydrolysis of these compounds. Mechanisms of acid-catalyzed reactions may parallel those catalyzed by (hydr)oxide minerals, while base-catalyzed processes have as important counterparts reactions with environmental nucleophiles (such as reduced sulfur species). The current study systematically investigates how the structure of nine Chloroacetamides affects their reactivity in 2 N NaOH, 2 N HCl, or 6 N HCl at 25 or 85 °C. Base-catalyzed hydrolysis proceeds either through an intermolecular SN2 reaction to hydroxy-substituted derivatives or (in a few cases) through amide cleavage, while both amide and ether group cleavages are observed under acidic conditions. Our results reveal that subtle differences in Chloroacetamide structure [notably the type of (alkoxy)alkyl substituent] can dramatically influence reactivity and reaction mechanism. Hydroxy-substituted, morpholinone, and seco...
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Removal of neutral Chloroacetamide herbicide degradates during simulated unit processes for drinking water treatment.
Water research, 2005Co-Authors: Michelle L. Hladik, A. Lynn Roberts, Edward J. BouwerAbstract:Abstract Four Chloroacetamide herbicides and 20 neutral Chloroacetamide derivatives (known to occur as their environmental degradates) were subjected to simulated drinking water treatment (coagulation, oxidation and adsorption). Coagulation with alum and ferric chloride, at doses for optimum turbidity removal, provided little to no ( K constants) correlated with K ow values.
Jinwei Zheng - One of the best experts on this subject based on the ideXlab platform.
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biodegradation of Chloroacetamide herbicides by paracoccus sp fly 8 in vitro
Journal of Agricultural and Food Chemistry, 2011Co-Authors: Jun Zhang, Jinwei Zheng, Bin Liang, Chenghong Wang, Shu CaiAbstract:A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six Chloroacetamide herbicides as carbo...
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Biodegradation of Chloroacetamide herbicides by Paracoccus sp. FLY-8 in vitro.
Journal of agricultural and food chemistry, 2011Co-Authors: Jun Zhang, Jinwei Zheng, Bin Liang, Chenghong Wang, Shu CaiAbstract:A butachlor-degrading strain, designated FLY-8, was isolated from rice field soil and was identified as Paracoccus sp. Strain FLY-8 could degrade and utilize six Chloroacetamide herbicides as carbon sources for growth, and the degradation rates followed the order alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor. The influence of molecular structure of the Chloroacetamide herbicides on the microbial degradation rate was first analyzed; the results indicated that the substitutions of alkoxymethyl side chain with alkoxyethyl side chain greatly reduced the degradation efficiencies; the length of amide nitrogen’s alkoxymethyl significantly affected the biodegradability of these herbicides: the longer the alkyl was, the slower the degradation efficiencies occurred. The phenyl alkyl substituents have no obvious influence on the degradation efficiency. The pathway of butachlor complete mineralization was elucidated on the basis of the results of metabolite identification and enzyme as...