Degradation of Selected Organophosphate Pesticides in Water and Soil

Virgil H. Freed, Cary T. Chiou, David W. Schmedding

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

Laboratory studies on the breakdown of several organophosphate pesticides both in aqueous solution and moist soil were conducted. The hydrolysis rates of phosmet, dialifor, malathion, methyl chlorpyrifos, dicapthon, chlorpyrifos, and parathion were measured at 20 and 37.5 °C (pH 7.4) in an aqueous system.A similar studywas carried out at 20 °C and pH 6.1. The half-lives at 20 °C (pH 7.4) range from 7.1h for phosmet to 130 days for parathion; the corresponding rates at 37.5 °C are approximately five-seven times greater than those at 20 °C. The rate equations at pH 7.4 were calculated from the 20 and 37.5°C data in an Arrhenius form : k = A exp(-Ea/RT). In moist soil (pH 6.2), degradation rates were measured at pesticide concentrations of approximately 1.0 and 0.1 ppm in a Willamette clay loam soil at a moisture level of 50% of field capacity. A comparison of the 20 °C half-lives for phosmet and dialifor in water and in moist soil at comparable pH indicates an appreciable increase in persistence for these two compounds, but little for the others in the soil-water system. This study was intended to evaluate the stabilities of several agricultural pesticides.

Original languageEnglish
Pages (from-to)706-708
Number of pages3
JournalJournal of Agricultural and Food Chemistry
Volume27
Issue number4
DOIs
Publication statusPublished - 1979 Feb 1

Fingerprint

organophosphorus pesticides
Organophosphates
Pesticides
phosmet
Phosmet
Soil
Soils
Degradation
degradation
Water
Parathion
parathion
chlorpyrifos
soil
water
half life
pesticides
Malathion
Chlorpyrifos
clay loam soils

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Agricultural and Biological Sciences(all)

Cite this

Freed, Virgil H. ; Chiou, Cary T. ; Schmedding, David W. / Degradation of Selected Organophosphate Pesticides in Water and Soil. In: Journal of Agricultural and Food Chemistry. 1979 ; Vol. 27, No. 4. pp. 706-708.
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Degradation of Selected Organophosphate Pesticides in Water and Soil. / Freed, Virgil H.; Chiou, Cary T.; Schmedding, David W.

In: Journal of Agricultural and Food Chemistry, Vol. 27, No. 4, 01.02.1979, p. 706-708.

Research output: Contribution to journalArticle

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