The behavior of air-sprayed fenitrothion (MEP) with a helicopter was examined at forest land of Kashima-cho, Shimane prefecture.
Most of the air-sprayed MEP was deposited on trees and shrubs. Consequently, the first rainfall after air spraying remarkably increased the concentration of MEP in soil and in water. However, no appreciable effusion or elution of MEP from soil was observed, owing to the strong adsorption of MEP on soil particles. Such an action of soil particles may prolong the persistence of MEP in soil. The half-life period of MEP in soil was evaluated to be 5.95 day.
On the other hand, MEP in water was rapidly decreased by microbial degradation. The half-life period of MEP (1.02 day) under fine weather differed from that of MEP (2.00 day) under cloudy or rainy weather. The difference in half-life period was attributed to the degradative action of sun light.