The gas-phase degradation of chlorpyrifos and chlorpyrifos-oxon towards OH radical under atmospheric conditions

Chemosphere. 2014 Sep:111:522-8. doi: 10.1016/j.chemosphere.2014.04.087. Epub 2014 May 22.

Abstract

The OH initiated oxidation of chlorpyrifos (a widely used insecticide) and its photooxidation product chlorpyrifos-oxon were investigated at the large outdoor European Photoreactor (EUPHORE). The rate constants for reaction of chlorpyrifos and chlorpyrifos oxon with OH radicals were measured using a conventional relative rate method. The value of the OH reaction rate constants with chlorpyrifos and chlorpyrifos-oxon were determined to be k=(9.1±2.1)×10(-11)cm(3)molecule(-1)s(-1) and (1.7±0.9)×10(-11)cm(3)molecule(-1)s(-1) at 303±5K and atmospheric pressure. They gave an atmospheric lifetime in relation to the reaction with OH of approximately 2h and 11h for chlorpyrifos and chlorpyrifos-oxon, respectively. Photolysis was found to be unimportant relative to reaction with OH. The main products detected in the gas phase from the reaction of OH with chlorpyrifos were SO2, chlorpyrifos-oxon, 3,5,6-trichloro-2-pyridinol and diethylphosphate with molar yields of 17±5%, ∼10%, 8±4% and 30±9%, respectively.

Keywords: Atmospheric degradation; Chlorpyrifos; Chlorpyrifos-oxon; Photooxidation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollutants / analysis
  • Air Pollutants / chemistry*
  • Atmosphere / analysis
  • Chlorpyrifos / analogs & derivatives*
  • Chlorpyrifos / analysis
  • Chlorpyrifos / chemistry
  • Gases / analysis
  • Gases / chemistry*
  • Hydroxyl Radical / chemistry*
  • Insecticides / analysis
  • Insecticides / chemistry*
  • Oxidation-Reduction
  • Photolysis
  • Pyridones / analysis

Substances

  • Air Pollutants
  • Gases
  • Insecticides
  • Pyridones
  • Hydroxyl Radical
  • O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate
  • 3,5,6-trichloro-2-pyridinol
  • Chlorpyrifos