Centennial‐Scale Storage of DOC Within Arctic Ocean Deep Waters Controlled by Subzero Temperatures
Year: 2025
Type: article
Abstract: Refractory dissolved organic carbon (RDOC) represents the second largest reservoir for ocean carbon storage, the bulk of which is held in the deep ocean, out of contact with the atmosphere on decadal to millennial timescales. Thus, understanding the mechanisms governing its production, delivery, and storage within the deep ocean is crucial for fully elucidating the oceanic carbon cycle and its impacts on global climate dynamics. Here we report observations of marine DOC across the Arctic, finding that the Eurasian Basin deep waters (>1,700 m) harbor the global maxima in deep water DOC concentrations. Given the basin's relatively long residence time (>150 years) and the absence of known RDOC delivery pathways into the ocean interior, we attempt to describe how the elevated Arctic Ocean deep water DOC is maintained. Using box model simulations, we find a significant role for brine rejection from continental shelf surface waters in delivering DOC to the abyss, which simultaneously ventilates Arctic Ocean deep waters. Comparison of kinetic loss rates for DOC consumption estimated as a function of subsurface temperatures demonstrates an elevated temperature sensitivity for Arctic RDOC relative to other ocean basins, possibly linked to its elevated terrigenous and/or “fresh” content, with the subzero temperatures of the Arctic currently suppressing DOC remineralization, helping to explain the deep water maxima. The Arctic Ocean currently stores ∼5.3 Pg C as DOC over the multi‐centennial scale residence times of its deep waters, which may be reduced by ∼1%–4% over the next century of warming.
Source: Global Biogeochemical Cycles
DOI: 10.1029/2024gb008428
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,070
Awards: Collaborative Research: US GEOTRACES Arctic Section - Water mass composition, circulation and mean residence times derived from measurements of natural and manmade tracers, Collaborative Research: US GO-SHIP 2021-2026 Repeat Hydrography, Carbon and Tracers, Collaborative Research: What controls the marine refractory DOC reservoir?
OpenAlex ID: W4409392016