Sources and distribution of sedimentary organic matter along the northern Bering and Chukchi Seas

Abstract

In this study, lignin-derived phenols were used to determine the sources and distribution of sedimentary organic matter along the northern Bering Sea and Chukchi Sea of the Arctic Ocean. The lignin parameter syringyl/vanillyl (S/V) and cinnamyl/vanillyl (C/V) ratios are used to indicate vegetation sources; and the ratios of vanillic acid/vanillin, (Ad/Al)v and syringic acid/syringaldehyde, (Ad/Al)s are used as indicators of lignin diagenesis. Results showed the predominance of woody gymnosperm signal at the easternmost location in the northern Bering Sea, a mixture of refractory non-woody angiosperm and fresher gymnosperm tissues in the Chukchi Sea, and signal of fresher woody gymnosperm tissues in the northernmost locations in the Chukchi Sea. The lignin materials showed gradual increase in decomposition stage during transport along the northern Bering Sea. Hydrodynamic sorting process, which is the retention of coarser materials nearshore and transportation of finer particles farther offshore, most probably occurred along the east coast of the northern Bering Sea. In Chukchi Sea, the non-woody angiosperm tissues could have originated from the Canadian Arctic and gymnosperm tissues could be from the Russian Arctic side. The fresher materials in the northernmost Chukchi Sea could have been transported here via the ice-rafting process. Detection of fresh lignin materials and the occurrence of lignin decomposition mean that this region could be sensitive to the impact of climate change.

Keywords: Chukchi Sea; Lignin-derived phenols; Northern Bering Sea.