TY - JOUR
T1 - Microbial Physiology Governs the Oceanic Distribution of Dissolved Organic Carbon in a Scenario of Equal Degradability
AU - Mentges, Andrea
AU - Deutsch, Curtis
AU - Feenders, Christoph
AU - Lennartz, Sinikka T.
AU - Blasius, Bernd
AU - Dittmar, Thorsten
N1 - Funding Information:
This work was funded by the Ministry of Science and Culture of Lower Saxony (Niedersächsisches Ministerium für Wissenschaft und Kultur) within the research training program Interdisciplinary approach to functional biodiversity research and the German Academic Exchange Service (DAAD) through a post-graduate scholarship. CD was supported by a grant from the Gordon and Betty Moore Foundation (GBMF#3775).
Funding Information:
We thank Helmut Hillebrand for his valuable contribution to model interpretation. This study includes results that were presented first in a doctoral thesis (Mentges, 2018). Funding. This work was funded by the Ministry of Science and Culture of Lower Saxony (Nieders?chsisches Ministerium f?r Wissenschaft und Kultur) within the research training program Interdisciplinary approach to functional biodiversity research and the German Academic Exchange Service (DAAD) through a post-graduate scholarship. CD was supported by a grant from the Gordon and Betty Moore Foundation (GBMF#3775).
Publisher Copyright:
© Copyright © 2020 Mentges, Deutsch, Feenders, Lennartz, Blasius and Dittmar.
PY - 2020/9/17
Y1 - 2020/9/17
N2 - Dissolved organic carbon (DOC) forms one of the largest active organic carbon reservoirs on Earth and reaches average radiocarbon ages of several thousand years. Many previous large scale DOC models assume different lability classes (labile to refractory) with prescribed, globally constant decay rates. In contrast, we assume that all DOC compounds are equally degradable by a heterotrophic microbial community. Based on this central assumption, we simulate DOC concentrations using a simple biogeochemical box model. Parameterized correctly, the simple model of neutral DOC uptake produced a recalcitrant carbon pool of 33 mmolC/m3, throughout the entire virtual ocean. The spatial distribution of DOC in the model was independent of the distribution of DOC sources from primary production and particle degradation. Instead, DOC concentrations were primarily driven by spatial gradients in microbial physiology, e.g., mortality rate or growth efficiency. Applying such a gradient, we find DOC concentrations of ~70 mmolC/m3 at the surface and ~35 mmolC/m3 in the deep ocean. Introducing model variations, such as seasonally-varying supply rates or temperature-dependent DOC uptake did not significantly alter model results. DOC spatial patterns are thus not necessarily shaped by the co-cycling of separate reactivity fractions, but can also arise from gradients in physiological parameters determining DOC uptake. We conclude that neutral DOC uptake can lead to realistic large-scale patterns of DOC concentration in the ocean.
AB - Dissolved organic carbon (DOC) forms one of the largest active organic carbon reservoirs on Earth and reaches average radiocarbon ages of several thousand years. Many previous large scale DOC models assume different lability classes (labile to refractory) with prescribed, globally constant decay rates. In contrast, we assume that all DOC compounds are equally degradable by a heterotrophic microbial community. Based on this central assumption, we simulate DOC concentrations using a simple biogeochemical box model. Parameterized correctly, the simple model of neutral DOC uptake produced a recalcitrant carbon pool of 33 mmolC/m3, throughout the entire virtual ocean. The spatial distribution of DOC in the model was independent of the distribution of DOC sources from primary production and particle degradation. Instead, DOC concentrations were primarily driven by spatial gradients in microbial physiology, e.g., mortality rate or growth efficiency. Applying such a gradient, we find DOC concentrations of ~70 mmolC/m3 at the surface and ~35 mmolC/m3 in the deep ocean. Introducing model variations, such as seasonally-varying supply rates or temperature-dependent DOC uptake did not significantly alter model results. DOC spatial patterns are thus not necessarily shaped by the co-cycling of separate reactivity fractions, but can also arise from gradients in physiological parameters determining DOC uptake. We conclude that neutral DOC uptake can lead to realistic large-scale patterns of DOC concentration in the ocean.
KW - DOC
KW - DOM
KW - box model
KW - marine
KW - microbial degradation
KW - reactivity
KW - recalcitrance
KW - stability
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U2 - 10.3389/fmars.2020.549784
DO - 10.3389/fmars.2020.549784
M3 - Article
AN - SCOPUS:85091944681
SN - 2296-7745
VL - 7
JO - Frontiers in Marine Science
JF - Frontiers in Marine Science
M1 - 549784
ER -