Organic Compounds in Heavy Oils Reached to Niigata Coastal Area

Abstract

A Russian-registered tanker, Nakhodka, has broken and sunk on January 2, 1997, in the Sea of Japan. A total of 6, 200 t of heavy oil has been spilled into the sea from the tanker; 3, 700 t of oil had reached to the coasts of Niigata Prefecture after the oil spill. To determine sources of the oils reached the coasts, 31 n-alkanes (C₁₀-C₄₀), eight alkyl dibenzothiophenes, 22 polycyclic aromatic hydrocarbons (PAHs) and 24 alkyl benzenes were identified from a drifted oil in the sea and nine oil patches reached to the coasts of the prefecture after the oil spill. The relative ratios of these compounds in the oil samples were compared with those in the heavy oil from the tanker.
A part of low molecular compounds, such as n-alkanes with C₁₀-C₁₅, PAHs with molecular weight of less than 200, as well as benzene, toluene and xylenes, were disappeared from the oils after spillage to the sea. On the other hand, the ratios of n-alkanes with C₁₆-C₄₀, alkyl dibenzothiophenes, PAHs with molecular weight of more than 200 and C4-benzenes in the drifted oil and eight oil samples from the coasts were same as those in the heavy oil from the tanker. This indicated strongly that these oils were spilled from the tanker.