Presentation Information
[U11-P02]Anthropocene Diatom Assemblages and Paleoceanographic Variability along the Alaskan Margin of the Arctic Ocean
*Masao IWAI1, Yuki Hamada2,3, Tatsuki Miyake2,4, Masanobu Yamamoto5 (1.Marine Core Research Institute, Kochi University, 2.Graduated Faculty of Science and Technology, Kochi University, 3.the BIKEN Foundation, 4.SANSHIN Co., Ltd., 5.Hokkaido University)
Keywords:
Arctic Ocean,diatom,late Holocene,Barrow Canyon,mouth of the Mackenzie River
Recent Arctic environmental changes may influence the Northern Hemispher and global climate, but high-resolution records from the western Arctic remain limited. We analyzed diatom assemblages in two sediment cores collected from the Alaskan Arctic coast : MT2 (152m-water depth; 39cm-length, 0-130yrBP) near the Mackenzie River and BC2 (224m-water depth; 27cm-length, 0-40yrBP) from Barrow Canyon. Samples were taken at every 1cm intervals, processed, and examined using Nomarski DIC microscopy, and diatom concentratins were calculated.
MT2 showed 1.0x104-1.0x105 valves/g-dry sediment and 12 taxa, while BC2 shows 1.0x105-1.0x106 valves/g-dry sedimentand 33 taxa.MT2 had higher concentration from AD2020-2000 domimated by cold-water and costal species, but diatoms sere neay detection limit below 27cm (befor AD1950). BC2 showed one order high value concentration from AD2020-2000 with similar taxa. Before AD2000, both cores were dominated by cold-water and coasteal species. These results suggest persistent sea-ice at MT2 befoeAD1950 and reduced se-ice after. AD2000.
MT2 showed 1.0x104-1.0x105 valves/g-dry sediment and 12 taxa, while BC2 shows 1.0x105-1.0x106 valves/g-dry sedimentand 33 taxa.MT2 had higher concentration from AD2020-2000 domimated by cold-water and costal species, but diatoms sere neay detection limit below 27cm (befor AD1950). BC2 showed one order high value concentration from AD2020-2000 with similar taxa. Before AD2000, both cores were dominated by cold-water and coasteal species. These results suggest persistent sea-ice at MT2 befoeAD1950 and reduced se-ice after. AD2000.