ORGANIC MATTER AND OIL-CONTAMINATED BOTTOM SEDIMENTS IN PETER THE GREAT BAY (SEA OF JAPAN)

This study focused on the origin of organic matter (OM) and its spatial distribution in the bottom sediments of Peter the Great Bay, as well as assessing the contamination by oil products. Low-molecular compounds with an even number of carbon atoms dominate the composition of n- and iso-alkanes. The compositional profile of saturated hydrocarbons and their ratios indicate a predominantly marine origin of organic matter, along with signs of bacterial transformation. Coastal zones are characterized by additional sources of organic matter, such as terrigenous runoff and coastal macrophytes, specifically plants of the genus Zostera (Eelgrass). Evidence of macrophyte presence was reported at deep-sea stations, presumably associated with the transport of coastal organic matter by episodic submesoscale eddies. In general, oil contamination of bottom sediments in Peter the Great Bay was assessed as weak; however, highly contaminated sediments were found locally in coastal areas with heavy maritime traffic, which may negatively affect the species diversity of the studied water areas.