INTRINSIC BIODEGRADATION OF HEAVY OIL FROM NAKHODKA AND THE EFFECT OF EXOGENOUS FERTILIZATION AT A COASTAL AREA OF THE SEA OF JAPAN

摘要

We performed a field experiment in the biodegradation of heavy oil spilled from the Russian tanker Nakhodka on a beach in the Sea of Japan. We collected oil-contaminated cobbles and treated half with nitrogen and phosphorus slow-release fertilizers to stimulate microbial degradation of the oil; the other half acted as unfertilized controls. The cobbles were placed in porous acrylic vessels and submerged. We monitored changes in the oils, macronutrients, microbial community structure and amount of chlorophyll a. There were no significant differences in these criteria between the fertilized and unfertilized vessels, apart from an increase in chlorophyll a in the fertilized vessels. However, there was a major intrinsic degradation of semi-volatile oil compounds in the unfertilized vessels; this occurred at a rate similar to that in the fertilized vessels, despite the low concentration of macronutrients in the seawater at the site.