Japan Geoscience Union Meeting 2016

Presentation information


Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS17] Paleoclimatology and paleoceanography

Tue. May 24, 2016 1:45 PM - 3:15 PM A04 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Tomohisa Irino(Faculty of Environmental Earth Science, Hokkaido University), Minoru Ikehara(Center for Advanced Marine Core Research, Kochi University), Akira Oka(Atmosphere and Ocean Research Institute, The University of Tokyo), Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Ikuko Kitaba(Research Centre for Palaleoclimatology, Ritsumeikan University), Akihisa Kitamura(Institute of Geosciences, Faculty of Science, Shizuoka University), Masaki Sano(Research Institute for Humanity and Nature), Ryuji Tada(Department of Earth and Planetary Science, Graduate School of Science, The Univeristy of Tokyo), Takeshi Nakagawa(Ritsumeikan University), Akira Hayashida(Department of Environmental Systems Science, Doshisha University), Chair:Masaki Sano(Research Institute for Humanity and Nature)

2:45 PM - 3:00 PM

[MIS17-29] Biomass burning history deduced from elemental carbon variability at IODP Exp. 346 Site U1423 during the last 4 million years

*Song Lu1, Tomohisa Irino2, Yaeko Igarashi3 (1.Graduate School of Environmental Science, Hokkaido University, 2.Faculty of Environmental Earth Science, Hokkaido University, 3.Institute for Paleoenvironment of Northern Regions)

Keywords:biomass burning, elemental carbon, IODP Expedition 346 Site U1423

The burning of trees and grasses produces charred particles such as charcoal and soot that may be transported long distances via winds and rivers to coastal, deltaic, and ocean environments where they may become preserved in the sediments. Charcoal contained in sediments has been widely used as a proxy for biomass burning and human activities as well as climate change. Charcoal and soot in Cenozoic marine sediments at IODP Exp. 346 Site U1423 was measured to examine the regional history of biomass burning in the East Asia and carbon sequestration in the ocean.
IODP Exp.346 Site U1423 is located in the northeastern Japan Sea and the water depth is 1785 m. Relatively low Linear sedimentation rates (LSRs) are anticipated based on results from the site survey. The LSR are likely to be low enough to detect the contribution of minor amount of charcoal or soot from the surrounding land. One hundred nine samples have been collected from interval between 0 and 200 m CCSF-D which cover the last 4.3 m.y. Charcoal and soot were measured as elemental carbon (EC) in coarse (>2 um) and fine (<2 um) fractions, respectively, using thermal optical transmittance (TOT) method followed by grain size separation using repeated settling. Organic carbon (OC) was also quantified during the process.
EC and OC in both coarse and fine fractions are higher from 0 to 1.8 Ma and lower from 1.8 to 4.3 Ma with large variation, which suggests more frequent or intense biomass burning since 1.8 Ma. The fact that dark layer samples contain higher OC and EC also suggests net carbon input or preservation controls the amount of OC and EC in the sediments. Comparison of OC and EC variabilities with vegetation change reconstructed from pollen analysis suggests that OC and EC was high both in coarse and fine fractions in warm and wet environment. Terrestrial biomass and precipitation could be major control on EC supply. Fine EC varies independently from coarse EC, which suggests remote origin of fine EC. High temperature resistive EC is associated with grass dominant vegetation, while coarse EC is lower (fine EC is higher) when wood vegetation is dominant suggesting that vegetation type could affect the type of burning products.