Dynamics of degradation and residue of 14C-fenvalerate in flooded paddy soils

The dynamics of degradation and residue of 14C-CN-Fenvalerate in two types of flooded paddy soils were examined under the laboratory modelling and the natural condition. Experiment results showed that Fenvalerate degraded slowly in the flooded soils the degradation was either by the hydration of the -14CN group of the molecule to produce-14CONH2 group, followed by forming-14COOH and releasing 14CO, or by the ring hydroxylation to produce 4'-OH-Fenvalerate. The two ways were dominant in flooded soils. 14CO2 released from soils increased with increasing time, their relationship of was significant and could be expcessed with an exponent equation. The hydration of the-14CN group and the ring hydroxylation both were related to the types of soil and soil microorganism. The disappearance of Fenvalerate in flooded soils was very slow. The extractable residue still was about 65% of Fenvalerate after 72 day's application. Half life of Fenvalerate in two soils was 117.5 days and 105 days. respectively. Fenvalerate had no sooner reached soil than the bound residue formed