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Carbofuran degradation in soil profiles
S L Trabue1, X Feng, A V Ogram
1Soil and Water Science Department, University of Florida, Gainesville 32611, USA.
Summary
Soils with prior carbofuran exposure show enhanced degradation of this pesticide. This enhanced degradation, observed in both surface and subsurface layers, involves faster mineralization and different breakdown pathways.
Area of Science:
- Environmental Chemistry
- Soil Science
- Agrochemical Degradation
Background:
- Carbofuran is a widely used pesticide, and understanding its environmental fate is crucial.
- Previous exposure to pesticides can alter soil properties and microbial communities, potentially affecting subsequent degradation rates.
- Different soil types (e.g., Puyallup fine sandy loam, Ellzey fine sand) possess unique pedological and climatological characteristics that influence pesticide behavior.
Purpose of the Study:
- To investigate the impact of prior carbofuran exposure on the degradation rates and pathways in two distinct soil types.
- To compare carbofuran mineralization and disappearance in previously treated soils versus untreated soils.
- To elucidate the specific degradation mechanisms (e.g., hydrolysis, oxidation) involved in treated and untreated soils.
Main Methods:
- Utilized two soil types: Puyallup fine sandy loam (WA) and Ellzey fine sand (FL), with and without prior carbofuran exposure.
- Measured carbofuran degradation by assessing mineralization rates of carbonyl and aromatic ring components using radiolabeled [14C-URL] carbofuran.
- Analyzed disappearance rates and identified degradation pathways (hydrolysis, oxidation) in surface and subsurface soil layers.
Main Results:
- Soils with prior carbofuran exposure exhibited enhanced degradation in both surface and subsurface layers compared to untreated soils.
- Treated soils showed significantly higher mineralization rates for both carbonyl and aromatic ring structures of carbofuran.
- Treated Ellzey soil demonstrated faster carbofuran disappearance and distinct degradation patterns, primarily via biological hydrolysis, unlike untreated soil's combined oxidative and hydrolytic processes.
Conclusions:
- Prior carbofuran exposure primes soils, leading to accelerated degradation and altered breakdown mechanisms.
- Enhanced biodegradation, particularly through hydrolysis, is a key outcome of repeated carbofuran application in susceptible soil types.
- Understanding these enhanced degradation phenomena is vital for predicting pesticide persistence and developing effective soil management strategies.