Effect of Temperature and Ultraviolet Radiation on the Persistence of Methyl Parathion and DDT in Soils¹

Abstract

The effect of temperature and ultraviolet (uv) radiation on the persistence of methyl parathion (o,o‐dimethylo, p‐nitrophenyl phosphorothionate) and DDT [2,2 bis(pchlorophenyl)‐l,l,l‐trichloroethane] in soils was studied using controlled environmental conditions. Biologically effective uv radiation (300 to 400 nm) was used. Three alkaline soil types were used in the study: Houston Black clay, Pima silty clay, and Pinal gravelly loam. Soils in petri dishes were treated with a mixture of methyl parathion and DDT at 5, 20, or 1,000 µg/g. The 5 and 20 µg/g treatments were used to quantitate the amount of pesticide remaining in the soils at periodic intervals. The 1,000 #g/g treatment was used for qualitative studies of breakdown products. Standard samples of pesticides were irradiated with uv radiation for qualitative studies. The results indicated that both temperature and uv radiation accelerated the loss of pesticides from soils. Temperature appeared to play a more important role in the loss of DDT than in methyl parathion. At each temperature (30 and 50 C) the addition of uv radiation accelerated the loss of both methyl parathion and DDT. There was a 29% or greater loss of DDT (depending upon the soil type), above that observed in the 50 treatment not receiving uv radiation. The only identifiable breakdown product of DDT in the soil extracts was DDE [2,2 bis(p‐chlorophenyl)‐l,1‐ dichloroethylene]. There were no breakdown products for methyl parathion in the soil extracts. The breakdown products from the irradiated standard samples of DDT and DDE were numerous. For DDT they included DDE, DDD [2,2 bis (p‐chlorophenyl)‐l,l‐dichloroethane], DBP (4,4'‐dichlorobenzophenone), and DDMU [1‐chloro‐ 2,2‐bis(p‐chlorophenyl)ethylene]. The oxon derivative methyl parathion. At each temperature (30 and 50 C) the addition of uv radiation accelerated the loss of both methyl parathion and DDT. There was a 29% or greater loss of DDT (depending upon the soil type) above that observed in the 50 C treatment not receiving uv radiation. The only identifiable breakdown product of DDT in the soil extracts was DDE [2,2 bis(p‐chlorophenyl)‐1,1‐dichloroethylene]. There were no breakdown products for methyl parathion in the soil extracts. The breakdown products from the irradiated standard samples of DDT and DDE were numerous. For DDT they included DDE, DDD [2,2 his (p‐chlorophenyl)‐1,1‐dichloroethane], DBP (4,4'‐dichlorobenzophenone), and DDMU [1‐chloro‐2,2‐bis(p‐chlorophenyl)ethylene]. The oxon derivative of methyl parathion was tentatively identified as a break‐down product of methyl parathion.

Distribution of DDT and toxaphene in Houston black clay on three watersheds

“…Surface soil temperatures of 60 °C have been measured in central Texas. Lahser and Applegate (1966) and Baker (1970) have also reported low recoverable quantities of ddt in soils from Presidio, Tex., and have indicated that volatilization was a major contributor to the loss of ddt.…”

“…Previous experiments (Allen et al, 1954;Edwards, 1964;Lichtenstein, 1958) showed that almost all of the DDT residue in soils could be recovered in the upper 6 in. Lahser and Applegate (1966) and Baker (1970) have also reported low recoverable quantities of DDT in soils from Presidio, Tex., and have indicated that volatilization was a major contributor to the loss of DDT. Toxaphene. The watersheds studied here are situated o n a Vertisol (Houston Black clay), which consist of 50 t o 60% clay and which is predominately montmorillonitic.…”

Molecular modeling of DDT's and it's major metabolites adsorption in the interlaminar space of montmorillonite

“…The DDD and DDE metabolites come from the dehydrochlorination of DDT and their physical and chemical properties are similar [18]. The dehydrochlorination and other types of catalyzed reactions that result in a change of the chemical structure are possible by enzymes, expressed by resistant insects and some species of bacteria and fungi [13,19,20], and a photooxidation mechanism of DDT and DDE has also been discovered [1,11,15].…”

The Effect of Ultraviolet Radiation and Di-1-p-Menthene on the Phytotoxicity of 2,4-D Applications to Black Valentine Bean Plants

“…It has been known for some time that exposure to radiation of the ultraviolet wavelength may affect biological systems and pesticides. Many com-,on herbicides exhibit their principal electronic absorption maxima in the ultraviolet region (200-400 nm) (7) and photodecomposition by ultraviolet light has been shown to occur in a number of pesticides (4,8,12) Including 2,4-D (9). The latter was found to decompose rapidi in the presencQ of water and ultraviolet irradiation at a wavelength of 254 nm.…”