Abstract
In the downstream of the Tamagawa river, the process of biodegradation of petroleum hydrocarbons was investigated.
Petroleum hydocarbons such as hexadecane, octylbenzene and 1-methylnaphtalene were rapidly degraded by microorganisms in the water sampled from the surface of the river after a period of lag time. The longer lag time was observed in order of hexadecane<octylbenzene<1-methylnaphtalene and was not shortened by physical and chemical emulsification. However, after the microorganisms were acclimated by these hydrocarbons, they were degraded without the lag time and the the rates could not be enhanced by physical and chemical emulsification. It seem that petroleum hydrocarbons were degraded not in physical and chemical process that the hydrocarbons were emulsified by microbial extracellular products, microfinded and enhanced contact area or frequency to microbes, but in biochemical process that the microorganisms gained the ability of petroleum hydrocarbons degradation, that is, induction of production of a degrading enzyme.
In the case where petroleum hydrocarbons is accidentally spilled out, they seemed likely not to be degrade immediately, but with the acclimation, they can be degraded rapidly.
