Abstracts

A Multi-Proxies Reconstruction of Biological Productivity in the Chukchi Sea for the Past 4.2 Kyr

Hongliang Li¹, Jianfang Chen², Haiyan Jin³, MingMing Jin⁴, HaiSheng Zhang⁵, ^6
1The Second Institute of Oceanography, SOA, Hangzhou, China, gambooli@hotmail.com
²The Second Institute of Oceanography, SOA, Hangzhou, China, Biogeo_Chen@hotmail.com
³The Second Institute of Oceanography, SOA, Hangzhou, China, Goldsea@hotmail.com
⁴The Second Institute of Oceanography, SOA, Hangzhou, China, Jinmm@hotmail.com
⁵The Second Institute of Oceanography, SOA, Hangzhou, China, Zhanghs@hotmail.com
⁶USA

A 340m sediment core located in the Chukchi Shelf (Arctic Ocean) has been studied to reconstruct rapid variations of paleoproductivity under the global warming, waning of the ice-sheets and changing of nutrients supply (via Bering Strait from North Pacific Ocean and surrounding large rivers) over the last 4.2kyr. The dating of stratigraphy of the core is based on 210Pb data. We studied changing marine productivity by a multi-proxies approach, involving total organic carbon (TOC), total nitrogen (TN), biogenic silica (BSi), organic carbon isotope (d13C). During the first stage (4200-250yr BP), the d13C ratio varied -24.75 per mil to -24.10 per mil suggested only 40% organic matter derived from marine algae in the Chukchi Sea. In contrast, the proportion of marine algae origined organic matter markedly increased in the second stage (250yr–present), especially in the last several decades marine algae contributed as much as 95% of total organic matter. The content of TOC, TN, and BSi increased slowly in the first stage, indicated the upper layer have a steady productivity of Chukchi Sea in this period, while the second stage is characterized by significant increasing productivity, mainly driven by silicate-producing organisms. This trend is consistent with the sea-ice variation of Arctic Ocean in the last century. Thus, our results suggest that as one of the largest shelves in the world (one-forth of world shelves), as well as it's sufficient nutrients supply (from north Pacific Ocean, large rivers), the Arctic Ocean might play a very important role in global carbon sink when sea ice shrinks.

Abstract Categories: 2.3 Arctic Change and Natural Variability