Nishida Prize

Youhei Yamashita


Biogeochemical studies on the optical traits and dynamics of dissolved organic matter in the hydrosphere

A list of five major papers

  • Yamashita, Y., M. Nakane, Y. Mori, J. Nishioka, and H. Ogawa (2022) Fate of dissolved black carbon in the deep Pacific Ocean. Nature Communications, 13, 307.
  • Yamashita, Y., J. Nishioka, H. Obata, and H. Ogawa (2020) Shelf humic substances as carriers for basin-scale iron transport in the North Pacific. Scientific Reports, 10, 4505.
  • Yamashita, Y., and R. Jaffé (2008) Characterizing the interactions between trace metal and dissolved organic matter using excitation-emission matrix and parallel factor analysis. Environmental Science and Technology, 42, 7374-7379.
  • Yamashita, Y., and E. Tanoue (2008) Production of bio-refractory fluorescent dissolved organic matter in the ocean interior. Nature Geoscience, 1, 579-582.
  • Yamashita, Y. , and E. Tanoue (2003) Chemical characterization of protein-like fluorophores in DOM in relation to aromatic amino acids. Marine Chemistry, 82, 255-271.

Major achievements

Dr. Youhei Yamashita pioneered the field of chemical analysis of dissolved organic matter in the hydrosphere to evaluate the environmental dynamics at the molecular level by developing methods.
1) He evaluated the dissolved organic matter at the molecular level with qualitative and quantitative analyses of aromatic amino acids combined with the fluorescence properties.
2) He applied multivariate analysis to statistically decompose spectral characteristics of fluorescent dissolved organic matter, which separated between autochthonous and allochthonous ones and made it possible to estimate their properties as organic ligands.
3) He showed that humic-like fluorescent dissolved organic matter complexes with iron and transports iron long distances in the ocean interior.
4) He is clarifying the environmental dynamics of dissolved black carbon in the ocean, mainly produced by biomass and fossil fuel combustion.
As shown by his achievements (79 peer-reviewed articles with total citations of more than 6000), it is clear that he has made a significant contribution to the essential understanding of organic matter dynamics and the carbon cycle in the hydrosphere.


Koji Suzuki


Jun Nishioka, Hiroshi Ogawa