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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2019-361
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-361
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 16 Sep 2019

Submitted as: research article | 16 Sep 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

DISCOL experiment revisited: Assessing the temporal scale of deep-sea mining impacts on sediment biogeochemistry

Laura Haffert1, Matthias Haeckel1, Henko de Stigter2, and Felix Janßen3 Laura Haffert et al.
  • 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1–3, 24148 Kiel, Germany
  • 2NIOZ – Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg – Texel, the Netherlands
  • 3HGF MPG Group for Deep Sea Ecology and Technology at the Max Planck Institute for marine Microbiology, Bremen and Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany Max-Planck Institute for marine Microbiology, Bremen, Germany

Abstract. Deep-sea mining for polymetallic nodules is expected to have severe environmental impacts because in addition to the nodules, benthic fauna as well as the upper reactive sediment layer is removed through the mining operation, and blanketed by resettling material from the suspended sediment plume. This study aims to provide a holistic assessment of the biogeochemical recovery after a disturbance event by applying prognostic simulations based on an updated diagenetic background model and validated with novel (micro)-biological data. It was found that the recovery strongly depends on the impact type; complete removal of the reactive surface sediment reduces seafloor nutrient fluxes over centuries, while geochemical processes after resuspension and mixing of the surface sediment are near pre-impact state one year after the disturbance. Furthermore, the geochemical impact in the DISCOL area would be mitigated to some degree by a clay-bound Fe(II)-reaction layer, impeding the downward diffusion of oxygen, thus stabilizing the redox zonation of the sediment during transient post-impact recovery. The interdisciplinary (geochemical, numerical and biological) approach highlights the closely linked nature of benthic ecosystem functions, e.g. through bioturbation, microbial biomass and nutrient fluxes, which is also of great importance for the system recovery.

Laura Haffert et al.
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Status: open (until 10 Nov 2019)
Status: open (until 10 Nov 2019)
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Laura Haffert et al.
Data sets

Radionuclide data (total 210Pb) measured on sediment multi cores during SONNE cruise SO242/1 at the DISCOL area, Peru Basin H. de Stigter https://doi.pangaea.de/10.1594/PANGAEA.905442

Radionuclide 210Pb and 226Ra data measured on sediment cores during SONNE cruise SO242/1 H. de Stigter https://doi.pangaea.de/10.1594/PANGAEA.905443

Geochemistry of sediment cores during SONNE cruises SO242/1 and SO242/2 at the DISCOL area, Peru Basin M. Haeckel https://doi.pangaea.de/10.1594/PANGAEA.905377

Laura Haffert et al.
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Short summary
Deep-sea mining for polymetallic nodules is expected to have severe environmental impacts. Through prognostic modelling, this study aims to provide a holistic assessment of the biogeochemical recovery after a disturbance event. It was found that the recovery strongly depends on the impact type: E.g. complete removal of the surface sediment reduces seafloor nutrient fluxes over centuries.
Deep-sea mining for polymetallic nodules is expected to have severe environmental impacts....
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