Loss of Carbofuran from Rice Paddy Water: Chemical and Physical Factors

Abstract

The loss of carbofuran was studied from rice paddy water treated with a granular formulation of the insecticide, and from ponds filled with drainage from the paddy. The average half-life (t1/2)for carbofuran loss was 57 hr. Controlled experiments indicated that pH was the predominating factor governing carbofuran loss from water in the environment studiec The loss due to hydrolysis was over 700 times more rapid at pH 10 (t1/2=1.2 hr.) than at pH 7 (t1/2=864 hr.) in buffered deionized water. The average pH of the rice paddy was 8, but diurnal fluctuations of 7 to 9.5 are common in similar environments. Impurities in the water, sunlight, and temperature influence the rate of carbofuran loss but not nearly so much as pH. There was no evidence for significant loss due to evaporation or oxidation. The results have important implications for the duration of the insecticide's activity and the effect on fish within or downstream from treated paddies. © 1978, Taylor & Francis Group, LLC. All rights reserved.

Source or Periodical Title

Journal of Environmental Science and Health, Part B

ISSN

3601234

Page

131-148

Document Type

Article

Subject

Carbofuran, pH-dependent hydrolysis, rice paddy water

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