In order to investigate waether soil microorganism prefer diazinon to humic substances as their substate, the growth of soil bacteria and the activities of monooxygenase and α-,β-esterase were measured after treatment of diazinon and humic substance...
In order to investigate waether soil microorganism prefer diazinon to humic substances as their substate, the growth of soil bacteria and the activities of monooxygenase and α-,β-esterase were measured after treatment of diazinon and humic substances in defined medium at 30±1℃. Also, the degradation rate of diazinon was determined by addition of humic substances to the medium. The number of soil bacteria was increased from 1 day and 3 days after the treatment with humic substances and diazinon, respectively. And it showed about 1.5 times more with humic substances than diazinon at 10 days. Monooxygenase(MO) activity with the treatment of humic substances was higher than diazinon until 3 days after treatment in the order of HA > FA > humin. Esterase(ES) activity with the treament of humin and HA was higher than dizainon from 5 dyas, but FA was much similar to diazinon. The degradation rate of diazinon showed more persistancy by addition of humic substances ; 51.4% with humin treatment, 58.9% with HA, 62.4% with FA and 71.9% in control at 10 days after treatment. Therefore, as soil microorganisms perfer humic substances to diazinon, the degreadation rate of diazinon might be delayed by addition of humic stbstances in submerged soil.