Biogeochemical cycles on the deep-sea floor revealed by isotope labeling experiments

Hidetaka NOMAKI

Presentation information

Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS21_28AM1] Biogeochemistry

Mon. Apr 28, 2014 9:00 AM - 10:45 AM 511 (5F)

Convener:*Muneoki Yoh(Tokyo University of Agriculture and Technology), Hideaki Shibata(Field Science Center fot Northern Biosphere, Hokkaido University), Naohiko Ohkouchi(Japan Agency for Marine-Earth Science and Technology), Youhei Yamashita(Faculty of Environmental Earth Science, Hokkaido University), Chair:Taichi Yokokawa(Center for Marine Environmental Studies, Ehime University), Hidetaka Nomaki(Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology), Yoshinori Takano(Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)), Seiya Nagao(Institute of Nature and Environmental Technology, Kanazawa University)

10:00 AM - 10:15 AM

[MIS21-05] Biogeochemical cycles on the deep-sea floor revealed by isotope labeling experiments

*Hidetaka NOMAKI¹ (1.JAMSTEC)

Keywords:Sediment-water interface, Benthos, isotope tracer, Biogeochemical cycle

Deep-sea benthic food webs are mainly sustained by sinking aggregates of phytodetritus derived from the water column. Although the majority of organic matter is consumed before reaching the deep-sea floor, phytodetritus still transports a significant amount of fresh material from the surface ocean to the seafloor. A portion of the phytodetritus is converted to benthic biomass, and the remaining refractory organic matter not utilized by the benthic community is preserved in the sedimentary record. The activity of the benthic community is thus expected to be an important factor in controlling the quality of organic matter, and biogeochemical cycles on the deep-sea floor. We carried out some different types of in situ isotope labeling experiments to reveal these benthic processes. Results quantitatively demonstrated the fate of phytoplankton, bacteria, dissolved organic carbon, and dissolved inorganic carbon on the deep-sea floor.