Fate of the herbicides mecoprop, dichlorprop, and 2,4-D in aerobic and anaerobic sewage sludge as determined by laboratory batch studies and enantiomer-specific analysis

Aerobic degradation experiments with the racemic mixtures of mecoprop and dichlorprop revealed that activated sludge collected from the aeration tank of a municipal waste water treatment plant degraded both enantiomers of mecoprop and dichlorprop within 7 days, albeit in an enantioselective manner; the (S) enantiomers were preferentially degraded. Mecoprop, dichlorprop, and 2,4-D were completely metabolized under aerobic conditions, as shown by the 86–98% elimination of dissolved organic carbon. Under anaerobic conditions, the concentration of 2,4-D decreased exponentially with a first-order reaction rate constant of 0.24 per day and without a lag-phase. After an incubation time of 17 days, 2,4-D was completely removed. 2,4-Dichlorophenol was the main metabolite of anaerobic 2,4-D degradation; only traces of 4-chlorophenol were detected. In contrast, the chiral phenoxypropionic acid herbicides mecoprop and dichlorprop persisted under anaerobic conditions during 49 days of incubation.

[1]  A. Smith.  Identification of 4-chloro-2-methylphenol as a Soil degradation product of ring-labelled [14C]mecoprop , 1985, Bulletin of environmental contamination and toxicology.

[2]  H. Hühnerfuss,et al.  Chromatographic separation of the enantiomers of marine pollutants. Part 5: Enantioselective degradation of phenoxycarboxylic acid herbicides by marine microorganisms , 1992 .

[3]  C. Rappe,et al.  Enantioselective determination of various chlordane components and metabolites using high-resolution gas chromatography with a β-cyclodextrin derivative as chiral selector and electron-capture negative ion mass spectrometry detection , 1997 .

[4]  H. Buser,et al.  Conversion Reactions of Various Phenoxyalkanoic Acid Herbicides in Soil. 1. Enantiomerization and Enantioselective Degradation of the Chiral 2-Phenoxypropionic Acid Herbicides , 1997 .

[5]  G. Heron,et al.  Degradation of the herbicide mecoprop in an aerobic aquifer determined by laboratory batch studies , 1992 .

[6]  D. Shelton,et al.  Anaerobic biodegradation of chlorophenols in fresh and acclimated sludge , 1984, Applied and environmental microbiology.

[7]  H. Buser,et al.  Conversion reactions of various phenoxyalkanoic acid herbicides in soil. 2. Elucidation of the enantiomerization process of chiral phenoxy acids from incubation in a D2O/Soil system , 1997 .

[8]  S. R. Daniel,et al.  Phenoxyalkanoic acid herbicides in municipal landfill leachates , 1992 .

[9]  M. Suter,et al.  Involvement of two alpha-ketoglutarate-dependent dioxygenases in enantioselective degradation of (R)- and (S)-mecoprop by Sphingomonas herbicidovorans MH , 1997, Journal of bacteriology.

[10]  H. Buser,et al.  Isomer and Enantioselective Degradation of Hexachlorocyclohexane Isomers in Sewage Sludge under Anaerobic Conditions. , 1995, Environmental science & technology.

[11]  W. Giger,et al.  Environmental Fate of Chiral Pollutants – the Necessity of Considering Stereochemistry , 1997, CHIMIA.

[12]  A. Zehnder,et al.  Enantioselective Uptake and Degradation of the Chiral Herbicide Dichlorprop [(RS)-2-(2,4-Dichlorophenoxy)propanoic acid] by Sphingomonas herbicidovorans MH , 1998, Journal of bacteriology.

[13]  H. Buser,et al.  Occurrence and Transformation Reactions of Chiral and Achiral Phenoxyalkanoic Acid Herbicides in Lakes and Rivers in Switzerland , 1998 .

[14]  C. Worthing,et al.  The pesticide manual, a world compendium. , 1979 .

[15]  W. Gujer,et al.  Behaviour of NTA and EDTA in biological wastewater treatment , 1990 .

[16]  Stefan B. Haderlein,et al.  Changes in the Enantiomeric Ratio of (R)- to (S)-Mecoprop Indicate in Situ Biodegradation of This Chiral Herbicide in a Polluted Aquifer , 1998 .

[17]  H. Lappin-Scott,et al.  Biodegradation of the chlorophenoxy herbicide (R)-(+)-mecoprop by Alcaligenes denitrificans , 2004, Biodegradation.

[18]  Antonius Kettrup,et al.  Enantiomeric Selectivity in the Environmental Degradation of Dichlorprop As Determined by High-Performance Capillary Electrophoresis , 1996 .

[19]  H. Kohler,et al.  Complete microbial degradation of both enantiomers of the chiral herbicide mecoprop [(RS)-2-(4-chloro-2-methylphenoxy)propionic acid] in an enantioselective manner by Sphingomonas herbicidovorans sp. nov , 1996, Applied and environmental microbiology.

[20]  M. Alexander,et al.  Herbicide Structure and Stability, Effect of Chemical Structure on Microbial Decomposition of Aromatic Herbicides , 1961 .

[21]  M. D. Mikesell,et al.  Reductive Dechlorination of the Pesticides 2,4‐D, 2,4,5‐T, and Pentachlorophenol in Anaerobic Sludges , 1985 .

[22]  S. Klinke,et al.  Enantioselective Metabolism of Chiral 3-Phenylbutyric Acid, an Intermediate of Linear Alkylbenzene Degradation, by Rhodococcus rhodochrous PB1 , 1996, Applied and environmental microbiology.

[23]  H. Lappin-Scott,et al.  Enantioselective degradation of the herbicide mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid] by mixed and pure bacterial cultures , 1994 .

[24]  H. M. Tsuchiya,et al.  Batch- and continuous-culture transients for two substrate systems. , 1972, Applied microbiology.