Biodegradation of fenitrothion in soil

Area of Science:

• Environmental Science
• Soil Science
• Pesticide Chemistry

Background:

• Organophosphorus pesticides like fenitrothion are widely used in agriculture.
• Understanding pesticide biodegradation in soil is crucial for environmental risk assessment.
• Fenitrothion's persistence and degradation pathways in tropical/subtropical soils require further investigation.

Purpose of the Study:

• To investigate the biodegradation of fenitrothion in garden soil from northern India.
• To identify and characterize the degradation metabolites of fenitrothion under varying temperature conditions.
• To elucidate the sequential steps involved in fenitrothion breakdown in soil.

Main Methods:

• Incubation of fenitrothion-treated natural and autoclaved soil at 25°C and 40°C for 90 days.
• Analysis of soil samples at regular intervals using High-Performance Liquid Chromatography (HPLC) to quantify residual fenitrothion.
• Purification and characterization of formed metabolites using HPLC and Infrared (IR) spectroscopy.

Main Results:

• Fenitrothion recovery was 98% initially and decreased linearly with incubation time.
• Two distinct metabolites were formed at 25°C, and three at 40°C.
• Metabolite characterization revealed a pathway involving oxidative desulphuration, P-O-aryl linkage hydrolysis, and demethylation.

Conclusions:

• Fenitrothion undergoes significant biodegradation in garden soil under the studied conditions.
• Temperature influences the rate and extent of fenitrothion degradation and metabolite formation.
• The identified degradation pathway provides insights into the environmental fate of fenitrothion.