[A-CC33] Ice cores and paleoenvironmental modeling

[ACC33-P03] Changes in black carbon concentrations and sizes at Dome Fuji, East Antarctica between 3 and 30 ka BP

*Kumiko Goto-Azuma¹, Kaori Fukuda¹, Jun Ogata¹, Nobuhiro Moteki², Tatsuhiro Mori³, Sho Ohata⁴, Yutaka Kondo¹, Makoto Koike⁵, Motohiro Hirabayashi¹, Kyotaro Kitamura¹, Ayaka Yonekura^6,1,7, Shuji Fujita^1,6, Fumio Nakazawa^1,6, Yoshimi Ogawa-Tsukagawa¹, Ikumi Oyabu^1,6, Kenji Kawamura^1,6 (1.National Institute of Polar Research, 2.Tokyo Metropolitan University, 3.Keio University, 4.Nagoya University, 5.The University of Tokyo, 6.SOKENDAI, 7.Marine Works Japan Ltd.)

Keywords:Black carbon, Ice Core, Dome Fuji, Antarctica, Biomass burning

Black carbon (BC) is an important light-absorbing aerosol species that influences Earth’s radiation budget. During preindustrial times, BC was primarily produced by biomass burning, such as wildfires. Emissions from large wildfires can impact air quality, ecosystems, and the climate. In turn, climate changes can alter the frequency and intensity of wildfires, influencing BC emissions. Despite numerous studies through observations and aerosol/climate models, our understanding of the impacts of BC on the radiation budget remains limited. Similarly, the effects of climate change on BC emissions are poorly understood. Ongoing global warming is expected to affect wildfire activity; however, predictions are constrained by the lack of long-term records of natural wildfires. Ice core BC data offer valuable insights into the history of natural wildfire activity.
In this study, we analyzed the second Dome Fuji deep ice core, drilled in East Antarctica, for a depth interval of 120 to 640 m. This depth interval corresponds to the period between 3-30 ka BP. Measurements were conducted using a recently developed Wide-Range Single Particle Soot Photometer (WR-SP2), which was attached to a Continuous Flow Analysis (CFA) system. This setup enabled high-resolution and accurate measurements of size distributions and concentrations of BC particles with diameters ranging from approximately 70 to 4,000 nm.
BC mass fluxes were calculated using BC mass concentrations and accumulation rate data. At Dome Fuji, BC mass fluxes were high during the LGM, decreased over Termination I, and increased again in the early Holocene. This temporal trend contrasts sharply with the BC mass fluxes at WAIS Divide, West Antarctica. Furthermore, we observed significant changes in the average mass of BC particles (mBC), an indicator of BC size distribution, during Termination I. The mBC values during the LGM were 3–4 times greater than those in the Holocene. Since BC in the Dome Fuji ice core likely originated from terrestrial regions surrounding Antarctica, such as South America, we analyzed variations in BC to assess the influence of climate change on biomass burning in these areas.