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

Haffert, Laura, Haeckel, Matthias, de Stigter, Henko and Janßen, Felix (2019) DISCOL experiment revisited: Assessing the temporal scale of deep-sea mining impacts on sediment biogeochemistry Biogeosciences Discussions . DOI 10.5194/bg-2019-361.

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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.

Document Type: Article
Keywords: Peru basin, manganese nodules, transport-reaction modelling, nutrient flux, bioturbation
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
AWI
NIOZ
Refereed: No
DOI etc.: 10.5194/bg-2019-361
ISSN: 1810-6285
Projects: MiningImpact
Expeditions/Models:
Date Deposited: 25 Sep 2019 08:16
Last Modified: 25 Sep 2019 10:16
URI: http://eprints.uni-kiel.de/id/eprint/47815

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