4th International Submarine Canyon Symposium (INCISE2018)

5-7 November 2018, Shenzhen, CHINA

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This is the detail of Benthic carbon mineralization in hadal trenches: Insights from in-situ determination of benthic oxygen consumption

< Back to List Version: 1047:1083 Status: Approved Edit Time: 2018/9/28 16:51:06


Author
Min Luo
Co-Author(s)
Ronnie N. Glud, Binbin Pan, Frank Wenzhöfer, Yunping Xu, Gang Lin, Duofu Chen
Abstarct Title
Benthic carbon mineralization in hadal trenches: Insights from in-situ determination of benthic oxygen consumption
Abstarct Body
Hadal trenches have been proposed as depocenters of organic material and hotspots for organic matter mineralization. In this study, we for the first time quantified the total benthic O2 uptake in hadal trenches using in-situ chamber incubations. Three trenches in the tropical Pacific were targeted and exhibited relatively high diagenetic activity given the great water depths, i.e., the Mariana Trench (2.0×102 μmol O2 m-2 d-1, 10,853 m), the Mussau Trench (2.7±0.1×102 μmol O2 m-2 d-1, 7,011 m), and the New Britain Trench (6.0±0.1×102 μmol O2 m-2 d-1, 8,225 m). Combined with carbon isotopic compositions (δ13C) and radiocarbon contents (Δ14C) of sedimentary TOC and previously published in-situ O2 microprofiles from hadal settings, we suggest that hadal benthic carbon mineralization partly is governed by the surface production but also is linked to the distance from land which controls the amount of terrigenous organic material being transported to the trench bottom. 210Pbxs profiles and burial of carbonate (up to 50%) at the New Britain Trench bottom reflected the recent occurrence of mass-wasting events possibly induced by the earthquake, which was responsible for the transfer of pre-aged, terrigenous organic matter to the trench bottom. Therefore, we highlight that terrestrial organic matter can be of importance in sustaining benthic communities in some hadal settings and hypothesize that hadal trenches may host a distinct microbial community that is capable of feeding on the old, refractory terrigenous organic matter.
INCISE Theme
Special Session: Canyons and trenches in the South China Sea and West Pacific
Presentation Type
Oral Presentation
Keywords
Hadal trenches; organic matter degradation; sediment instability

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