Dissipation of acetochlor and its distribution in surface and sub-surface soil fractions during laboratory incubations

Taylor, Jason P. and Mills, Margaret S. and Burns, Richard G. (2005) Dissipation of acetochlor and its distribution in surface and sub-surface soil fractions during laboratory incubations. Pest Management Science, 61 (6). pp. 539-548. ISSN 1526-498X. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Pesticides in soil are subject to a number of processes that result in transformation and biodegradation, sorption to and desorption from soil components, and diffusion and leaching. Pesticides leaching through a soil profile will be exposed to changing environmental conditions as different horizons with distinct physical, chemical and biological properties are encountered. The many ways in which soil properties influence pesticide retention and degradation need to be addressed to allow accurate predictions of environmental fate and the potential for groundwater pollution. Degradation and sorption processes were investigated in a long-term (100 days) study of the chloroacetanilide herbicide, acetochlor. Soil cores were collected from a clay soil profile and samples taken from 0-30 cm (surface), 1.0-1.3 m (mid) and 2.7-3.0 m (deep) and treated with acetochlor (2.5, 1.25, 0.67 microg acetochlor g(-1) dry wt soil, respectively). In sterile and non-sterile conditions, acetochlor concentration in the aqueous phase declined rapidly from the surface and subsoil layers, predominantly through nonextractable residue (NER) formation on soil surfaces, but also through biodegradation and biotic transformation. Abiotic transformation was also evident in the sterile soils. Several metabolites were produced, including acetochlor-ethane sulphonic acid and acetochlor-oxanilic acid. Transformation was principally microbial in origin, as shown by the differences between non-sterile and sterile soils. NER formation increased rapidly over the first 21 days in all soils and was mainly associated with the macroaggregate (>2000 microm diameter) size fractions. It is likely that acetochlor is incorporated into the macroaggregates through oxidative coupling, as humification of particulate organic matter progresses. The dissipation (ie total loss of acetochlor) half-life values were 9.3 (surface), 12.3 (mid) and 12.6 days (deep) in the non-sterile soils, compared with 20.9 [surface], 23.5 [mid], and 24 days [deep] in the sterile soils, demonstrating the importance of microbially driven processes in the rapid dissipation of acetochlor in soil.

Item Type: Article
Additional information: 1526-498X (Print) Journal Article
Uncontrolled keywords: Biodegradation, Environmental Herbicides/*chemistry Soil/*analysis Soil Microbiology Time Factors Toluidines/*chemistry
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Sue Davies
Date Deposited: 05 Sep 2008 11:42
Last Modified: 07 May 2014 09:27
Resource URI: https://kar.kent.ac.uk/id/eprint/6735 (The current URI for this page, for reference purposes)
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