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High carbon mineralization rates in subseafloor hadal sediments - Result of frequent mass wasting
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  • Matthias Zabel,
  • Ronnie N Glud,
  • Hamed Sanei,
  • Marcus Elvert,
  • Thomas Pape,
  • Pei-Chuan Chuang,
  • Emmanuel Okuma,
  • Patrizia Geprägs,
  • Martin Kölling
Matthias Zabel
Bremen University

Corresponding Author:mzabel@uni-bremen.de

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Ronnie N Glud
Southern Danish University
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Hamed Sanei
Department of Geoscience University Aarhus
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Marcus Elvert
University of Bremen
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Thomas Pape
MARUM - Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen
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Pei-Chuan Chuang
GEOMAR Helmholtz Centre for Ocean Research
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Emmanuel Okuma
University of Bremen - Faculty of Geosciences
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Patrizia Geprägs
University of Bremen
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Martin Kölling
University of Bremen
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In the past 20 years, the exploration of deep ocean trenches has led to spectacular new insights. Even in the deepest canyons, an unusual variety of life and unexpectedly high benthic oxygen consumption rates have been detected while microbial processes below the surface of the hadal seafloor remains largely unknown. The information that exist comes from geophysical measurements, especially related to seismic research, and specific component analyses to estimate the carbon export. In contrast, no information is available on metabolic activities in deeper buried sediments of hadal environment. Here we present the first pore water profiles from 15 up to 11 m long sediment cores recovered during three expeditions to two hadal zones, the Japan Trench and the Atacama Trench. Despite low levels of organic debris, our data reveal that rates of microbial carbon turnover along the trench axes can be similar to those encountered in much shallower and more productive oceanic regions. The extreme sedimentation dynamics, characterized by frequent mass wasting of slope sediments into the trenches, result in effective burial of reactive, microbially available, organic material. Our results document the fueling of the deep hadal biosphere with bioavailable material and thus provide important understanding on the function of deep-sea trenches and the hadal carbon cycle.