Crude Oil Bioremediation Field Experiment at a shore in the Sea of Okhotsk in Hokkaido, Japan

No abstracts are to be cited without prior reference to the author.

Experimental bioremediation of crude oils was conducted approximately for 6 months at a sandy beach in Mombetsu Port (Hokkaido) of the Sea of Okhotsk. Artificial mixtures of Sakhalin Vityaz crude oil (SVCO) and/or weathered Arabian light crude oil (ALCO) and sand taken from the experimental site were wrapped in teflon net envelopes. The envelopes were placed in stainless-net box cages that were buried in the intertidal zone of at a sandy beach in Mombetsu Port. Synthetic slow release nitrogen and phosphorus fertilizers were added to the oil–sand mixtures to supply more macronutrients to indigenous oil-degrading microbes. Some oil–sand mixtures were unfertilized controls. The oil–sand mixtures were periodically sampled and the residual oils were subjected to gas chromatography coupled with mass spectrometry to evaluate the depletions of some semi-volatile hydrocarbons. Fertilization significantly stimulated the degradation rate of alkanes contained in ALCO but didn’t that of ones in SVCO. Alkanes in SVCO were shown to be different from ones in ALCO in terms of behaviors such as retention times on gas chromatography and degradability. Although apparent natural attenuations of every hydrocarbon in unfertilized control cages were observed, degradations of any aromatic hydrocarbon both in ALCO and SVCO were not significantly accelerated by fertilization.