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Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 14, issue 9
Biogeosciences, 14, 2561–2570, 2017
https://doi.org/10.5194/bg-14-2561-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 14, 2561–2570, 2017
https://doi.org/10.5194/bg-14-2561-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 17 May 2017

Research article | 17 May 2017

Strong linkages between surface and deep-water dissolved organic matter in the East/Japan Sea

Tae-Hoon Kim1, Guebuem Kim2, Yuan Shen3, and Ronald Benner3,4 Tae-Hoon Kim et al.
  • 1Department of Earth and Marine Sciences, Jeju National University, Jeju, 63243, Republic of Korea
  • 2School of Earth and Environmental Sciences/Research Institute of Oceanography, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
  • 3Marine Science Program, University of South Carolina, Columbia, South Carolina 29208, USA
  • 4Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA

Abstract. Vertical and horizontal distributions of total dissolved amino acids (TDAAs), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) were measured in the East/Japan Sea (EJS). The euphotic zone of this sea is N-limited, and the N : P ratio is ∼ 13 below 200 m depth. Elevated TDAA concentrations (137 ± 34 nM) and DOC-normalized yields (0.8 ± 0.2 % of DOC) were observed in deep waters ( ≥  1000 m) of the EJS and compared with those in the deep North Pacific Ocean. Significantly high TDAA concentrations and yields were observed in a region of deep-water formation, indicating the convection of margin-derived bioavailable dissolved organic matter (DOM) to deep waters. Declining TDAA concentrations (36 ± 12 %) and yields (33 ± 13 %) were observed between 1000 and 3000 m throughout the EJS, indicating the utilization of bioavailable DOM in deep waters. Concentrations of the D-enantiomers of amino acids (Ala, Glx, Asx, and Ser) were relatively high in deep waters of the EJS, indicating substantial bacterial contributions to DOM from surface and upper mesopelagic waters. Climate warming during the past few decades in the EJS is weakening deep convection during the winter, and one consequence of this reduction in deep convection is a decline in the supply of bioavailable DOM from surface waters.

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Short summary
Significantly high total hydrolysable amino acid concentrations and yields were observed in the East/Japan Sea of deep-water formation, indicating the convection of margin-derived bioavailable dissolved organic matter to deep waters. Our observational results suggest that the effective transport of bioavailable DOM to the deep ocean can be significantly sensitive to changes in the deep-water renewal rates and in temperature of the surface ocean, linked to global warming.
Significantly high total hydrolysable amino acid concentrations and yields were observed in the...
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