Degradation and behavior of chlorpyrifos-methyl and propoxur in soil : a comparison between Thailand and Oregon soils Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/765374823

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Chlorpyrifos-methyl, an organophosphate insecticide, and propoxur, a carbamate insecticide both widely used in Thailand, were studied in the laboratory for degradation and behavior in two Thai and two Oregon soils. The purpose of the study was to ascertain the comparative persistence and to measure behavior such as adsorption, evaporation and leaching in the soil environment as a background for predicting or estimating the hazard that may be presented by these two chemicals. The degradation studies of chlorpyrifos-methyl were conducted on four different soils; clay and loamy sand from Thailand, and silt loam and loam soil from Oregon. The variables used included three different temperatures: 1.7 C (35 F), 23 C (70 F), and 32 C (89.6 F); three moisture contents: saturation, field capacity, and midway between field capacity and wilting point at a temperature of 30 C; and pH of 6.5 and 7.3 for the loamy sand at moisture content midway between field capacity and wilting point at 30 C temperature. The effect of the two chemicals on microorganismal activity was studied using [superscript 14]C-glucose as an indicator in clay and silt loam soils at 30 C at saturated moisture content. The adsorption of chlorpyrifos-methyl on clay and silt loam soils was determined at 23 C. The vapor pressure of propoxur at 23 C and 32 C was determined. The evaporation rate of chlorpyrifos-methyl and propoxur from clay and silt loam soils at 32 C was measured. Leaching of the two chemicals in clay and silt loam was measured in soil columns to compare their mobility. Considerable variation at different sampling intervals in the degradation study made precise calculation of half-life and rate impossible. However, a consistent trend in degradation as affected by each environmental factor was apparent. The chlorpyrifos-methyl degradation rate responded to temperature: 32 C > 23 C > 1.7 C; and moisture: midway between field capacity and wilting point > field capacity > saturation; soils: loamy sand > clay > silt loam > loam. Both chlorpyrifos-methyl and propoxur showed degradation in loamy sand at pH 7.3 > pH 6.5. The effect on microbial activity as evidenced by [superscript 14]C- glucose metabolism was chlorpyrifos-methyl > propoxur on silt loam and propoxur > chlorpyrifos-methyl on clay soil. The microbial activity depended on the concentration of these two chemicals, and was 100 ppm > 500 ppm > 1000 ppm for a 1-3 hours incubation period. Metabolism with the chemicals was higher than the control after 4 hours. The distribution coefficient (Kd) of chlorpyrifos-methyl was 93.1 on clay and 76.9 on silt loam. The relative evaporation rate of chlorpyrifos-methyl was field capacity > air dry soil and silt loam > clay soil. The vapor pressure of pure propoxur determined at 23 C was 3.5 x 10⁻⁶ mm Hg and 1.5 x 10⁻⁵ mm Hg at 32 C. The calculated latent heat of evaporation was 29 Kcal/mole. Chlorpyrifos-methyl was less mobile than propoxur. The leachate of chlorpyrifos-methyl contained less than 0.1 % and 0.5 % of the initial concentration for the clay and silt loam soils respectively, but 56 % and 60 % of propoxur was found leached from the clay and silt loam soils.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using ScandAll PRO 1.8.1 on a Fi-6770A in PDF format. CVista PdfCompressor 5.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Deborah Campbell(deborah.campbell@oregonstate.edu) on 2013-07-16T16:34:41Z (GMT) No. of bitstreams: 1 BiadulPongsri1987.pdf: 533812 bytes, checksum: da7c6f16aa1e905bfcd96ceecd2c1a6c (MD5)
  • description.provenance : Submitted by Kim Stowell (ksscannerosu@gmail.com) on 2013-06-26T16:34:11Z No. of bitstreams: 1 BiadulPongsri1987.pdf: 533812 bytes, checksum: da7c6f16aa1e905bfcd96ceecd2c1a6c (MD5)
  • description.provenance : Made available in DSpace on 2013-07-16T16:34:41Z (GMT). No. of bitstreams: 1 BiadulPongsri1987.pdf: 533812 bytes, checksum: da7c6f16aa1e905bfcd96ceecd2c1a6c (MD5) Previous issue date: 1986-08-01
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-06-27T14:42:15Z (GMT) No. of bitstreams: 1 BiadulPongsri1987.pdf: 533812 bytes, checksum: da7c6f16aa1e905bfcd96ceecd2c1a6c (MD5)

Relationships

In Administrative Set:
Last modified: 08/23/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items