GEOCHEMISTRY OF POLYCYCLIC ARENES ALONG RIVER-SEA SECTIONS

Abstract

The formation and transformation of organic matter (OM) along a river-sea section are considered for sediments of the Ob Bay, Yenisei Bay, and Kara Sea. It was shown that a large amount of mainly pelite-size sediments rich in terrigenous OM are precipitated and deposited in the northern part of the estuaries and adjacent shelf. However, the flows of sedimentary matter and organic carbon in the open part of the Kara Sea are consistent with the assumed ultraoligotrophic character of this basin, that is, the terrigenous constituent regularly decreases toward the pelagic zone. Simultaneously, polycyclic aromatic hydrocarbons (PAH) show a distinct decrease, the most significant decrease for perylene. In addition, the sediments confined to the inner boundary of the marginal filter show an abrupt increase in PAH contents, which is symbatic to general changes in the geochemical parameters of OM. The most significant increase is typical of molecular group 178 and its constituents, alkylphenanthrenes, which are the final products in the multistage diagenetic transformation of abictic acid.