Akira Iguchi

Development of nature-positive ocean-based negative emission technologies

Grant No.：JPMJCR25J1

Research Director : Akira Iguchi

Collaborator

Mayuri Inoue	Professor Faculty of Environmental, Life, Natural Science and Technology Okayama University
Kazuhiro Sayama	Principal Researcher Global Zero Emission Research Center National Institute of Advanced Industrial Science and Technology (AIST)
Masahiro Hayashi	Marine Biology Group Manager Central Research Laboratory Marine Ecology Research Institute

Outline

We develop ocean based negative emission technologies (Ocean NETs) that maximize the ocean’s inherent CO₂ absorption capacity while considering environmental impacts. We deepen various electrochemical direct ocean capture methods and alkalinity enhancement techniques, while establishing a methodology for neutral comparative evaluation using advanced environmental impact assessment techniques. We contribute comprehensively to the early societal implementation of nature-positive ocean NETs.

Shigeyoshi Otosaka

Carbon dynamics and sequestration of offshore blue carbon

Grant No.：JPMJCR25J2

Research Director : Shigeyoshi Otosaka

Collaborator

Yusuke Uchiyama	Professor Graduate School of Engineering Kobe University
Kazuhiro Misumi	Senior Research Scientist Sustainable System Research Laboratory Central Research Institute of Electric Power Industry

Outline

By combining novel ocean observations and marine ecosystem models, we will quantitatively evaluate the function of offshore blue carbon, which effectively sequestrates organic carbon from the ocean surface to the seafloor. By combining advanced analysis of sediment with a marine particle transport model near the seafloor, we will also elucidate the impact of bottom topography and environmental changes on offshore blue carbon. The main target area of this study is the continental slope, which is a major absorber of atmospheric carbon dioxide, and we aim to manage and utilize the carbon sequestration function over a wide area connecting land, coastal areas, and the open ocean.

Masaru K Nobu

Innovating ocean models through discovery of hidden microbial carbon flow

Grant No.：JPMJCR25J3

Research Director : Masaru K Nobu

Collaborator

Shigeki Ehira	Professor Graduate school of Science Tokyo Metropolitan University
Yusuke Tsukatani	Senior Researcher Institute for Earth and Material Sciences (EMS) Japan Agency for Marine-Earth Science and Technology
Ryohei Yamaguchi	Associate Professor Atmosphere and Ocean Research Institute The University of Tokyo

Outline

The ocean’s carbon cycle has traditionally been viewed as beginning with phytoplankton growth. In this project, we focus instead on the release of organic compounds by phytoplankton under nutrient limitation, especially in nutrient-poor regions of the open ocean, an overlooked source of carbon. We will investigate how these compounds influence microbial activity, how their composition and elemental balance shift with environmental change, and how they affect long-term carbon storage. By combining research cruise observations with laboratory experiments, we aim to develop a new model of the ocean carbon cycle that integrates the overlooked role of microbial carbon fluxes in regulating carbon flow and storage.

Youhei Yamashita

Marine storage of humic-like fluorescent dissolved organic matter: quantitative assessment and future projections

Grant No.：JPMJCR25J4

Research Director : Youhei Yamashita

Collaborator

Akira Ijiri	Professor Ocean-Bottom Exploration Centor Kobe University
Morimaru Kida	Associate Professor Graduate School of Agricultural Science Kobe University
Masahito Shigemitsu	Scientist Research Institute for Global Change Japan Agency for Marine-Earth Science and Technology

Outline

In order to accurately estimate the ocean’s CO2 absorption flux and predict its future changes, it is necessary to understand the behavior of recalcitrant, non-living organic carbon pools. This project focuses on ultra-recalcitrant, humic-like fluorescent dissolved organic matter (FDOM), which is produced by marine microorganisms. We will develop an equation to enable the conversion of FDOM fluorescence intensity into carbon concentration. By combining this equation with large-scale observations and biogeochemical models of FDOM in the ocean, we will be able to quantify the global FDOM production flux and predict how it will change in the future due to global warming.