Chlorpyrifos degradation in Turkish soil.
Degradation of chlorpyrifos was evaluated in laboratory studies. Surface (0-15 cm) and subsurface (40-60 cm) clay loam soils from a pesticide-untreated field were incubated in biometer flasks for 97 days at 25 degrees C. The treatment was 2 micrograms g-1 [2,6-pyridinyl-14C] chlorpyrifos, with 74 kBq radioactivity per 100 g soil flask. Evolved 14CO2 was monitored in KOH traps throughout the experiment. Periodically, soil subsamples were also methanol-extracted [ambient shaking, then supercritical fluid extraction (SFE)], then analyzed by thin-layer chromatography. Total 14C and unextractable soil-bound 14C residues were determined by combustion. From the surface and subsurface soils, 41 and 43% of the applied radiocarbon was evolved as 14CO2 during 3 months incubation. The time required for 50% loss of the parent insecticide in surface and subsurface soils was about 10 days. By 97 days, chlorpyrifos residues and their relative concentration (in surface/subsurface) as % of applied 14C were: 14CO2 (40.6/42.6), chlorpyrifos (13.1/12.4), soil-bound residues (11.7/11.4), and 3,5,6-trichloropyridinol (TCP) (3.8/4.8). Chlorpyrifos was largely extracted by simple shaking with methanol, whereas TCP was mainly removed only by SFE. The short persistence of chlorpyrifos probably relates to the high soil pH (7.9-8.1).
Turkish Atomic Energy Authority, Ankara Nuclear Research and Training Center, Turkey.
U
U
Yücel
M
M
Ylim
K
K
Gözek
C S
CS
Helling
Y
Y
Sarýkaya
D000383:Agriculture; D004390:Chlorpyrifos / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000378:metabolism*; D000432:Methanol; D008956:Models, Chemical; D012989:Soil Pollutants / Q000378:metabolism*; D012997:Solvents; D014421:Turkey
D007306:Insecticides; D012989:Soil Pollutants; D012997:Solvents; D004390:Chlorpyrifos; D000432:Methanol