Letter abstract


Nature Geoscience 1, 579 - 582 (2008)
Published online: 17 August 2008 | doi:10.1038/ngeo279

Subject Categories: Biogeochemistry | Oceanography

Production of bio-refractory fluorescent dissolved organic matter in the ocean interior

Youhei Yamashita1,2 & Eiichiro Tanoue1

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Dissolved organic matter in the ocean constitutes one of the largest pools of reduced carbon on the Earth's surface1, 2, but its role in the global carbon cycle is poorly understood. A large part of this pool is thought to be of marine origin2, 3, 4 and to be composed of constituents that are resistant to biological degradation3, 4, 5, 6. It is not clear how this refractory fraction of the carbon pool is produced in the ocean. Here, we analyse observations of fluorescence intensity and apparent oxygen utilization in the interior of the Pacific Ocean, and find that the two parameters are linearly related in the mesopelagic and abyssal layers. We conclude that fluorescent dissolved organic matter is produced in situ in the ocean interior as organic matter is oxidized biologically, and that it is resistant to biological degradation on centennial to millennial timescales. The rate of production of bio-refractory fluorescent dissolved organic matter in the ocean interior is larger than the riverine input of terrestrial humic substances, suggesting that its in situ production is one of the key processes in maintaining the oceanic pool of refractory dissolved organic matter.

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  1. Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
  2. Present address: Southeast Environmental Research Center, and Department of Chemistry and Biochemistry, Florida International University, University Park, OE-148, Miami, Florida 33199, USA

Correspondence to: Youhei Yamashita1,2 e-mail: yamashiy@fiu.edu



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