ENHANCED DEGRADATION OF PESTICIDES

Chung, Keun-Yook

Environmental Engineering Research 2000;5(1): 47-61.

Keun-Yook Chung^†

Institute of Construction Technology, Chungbuk National University, Cheongju, Korea

Corresponding Author: Keun-Yook Chung ,

Received: December 12, 1999; Accepted: January 13, 2000.

ABSTRACT

Pesticides should be persistent for an appropriate time to effectively control target pests in soils. Pesticides in soils are subject to transport (volatilization and leaching) as well as transformation (degra¬dation). The transport mechanism translocates a pesticide from one soil compartment to another without appreciable decrease in the total mass of chemical. Abiotic and biotic transformations are the most important mechanisms for detoxifying pesticides in soils. Abiotic transformations are sometimes involved in the partial degradation of pesticides, resulting in accumulation of metabolites in soils. Biological degradation, however, may lead to complete detoxification; i.e., complete mineralization to CO₂, H₂O, and inorganic ions. A variety of metabolic reactions are involved in the biological degradation of pesticides. Some pesticides are degraded more rapidly by microbial populations adapted following repeated application of the pesticides to the same soil, which is called enhanced degradation. Enhanced degradation of pesticides often results in poor control of target pests. Consequently, crop production can be greatly reduced. Even though enhanced degradation may result in reduced pesticidal efficacy and thus poor crop yield, this is offset by reduced chance for pesticide contamination of groundwater. Cross-enhancement or cross adaptation often explain the enhanced degradation of one pesticide after pretreatment of the soil with another. Two general strategies, such as operational and technological strategies, can overcome the enhanced degradation of pesticide.

Keywords: enhanced degradation | adaptation | pesticide | persistence | detoxification