Degradation of [14C]isofenphos in soil in the laboratory under different soil pH's, temperatures, and moistures.
The effects of three soil pH's, three soil temperatures, and three soil moistures on [14C]isofenphos degradation were investigated. All three factors interacted strongly and significantly affected the persistence of isofenphos as well as the formation of the degradation products (p less than 1%). Isofenphos degradation was greatest at the higher temperatures 35 degrees C greater than 25 degrees C greater than 15 degrees C (except under alkaline pH's), medium moisture 25% greater than 30% greater than 15%, and in both alkaline (pH = 8) and acidic soils (pH = 6) compared with neutral soil (pH = 7). Isofenphos oxon formation was greatest at higher temperatures 35 degrees C compared with 25 degrees C and 15 degrees C, in acidic soil greater than neutral soil greater than alkaline soil, and under high moisture (30%) compared with the 15% and 22.5% moistures. The formation of soil-bound residues was greatest at higher temperatures 35 degrees C greater than 25 degrees C greater than 15 degrees C, higher moisture 30% compared with 15% and 22.5%, and in alkaline soil compared with neutral and acidic soils.
Abou-Assaf
N
N
Department of Entomology, Iowa State University, Ames 50011.
Coats
J R
JR
D001673:Biodegradation, Environmental; D002855:Chromatography, Thin Layer; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000032:analysis*; D009946:Organothiophosphorus Compounds / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D013696:Temperature; D014867:Water / Q000032:analysis
D007306:Insecticides; D009946:Organothiophosphorus Compounds; D012987:Soil; D012989:Soil Pollutants; C035019:isofenphos; D014867:Water