Title: Preferential remineralization of dissolved organic phosphorus and non‐Redfield DOM dynamics in the global ocean: Impacts on marine productivity, nitrogen fixation, and carbon export

Abstract

Abstract Selective removal of nitrogen (N) and phosphorus (P) from the marine dissolved organic matter (DOM) pool has been reported in several regional studies. Because DOM is an important advective/mixing pathway of carbon (C) export from the ocean surface layer and its non‐Redfieldian stoichiometry would affect estimates of marine export production per unit N and P, we investigated the stoichiometry of marine DOM and its remineralization globally using a compiled DOM data set. Marine DOM is enriched in C and N compared to Redfield stoichiometry, averaging 317:39:1 and 810:48:1 for C:N:P within the degradable and total bulk pools, respectively. Dissolved organic phosphorus (DOP) is found to be preferentially remineralized about twice as rapidly with respect to the enriched C:N stoichiometry of marine DOM. Biogeochemical simulations with the Biogeochemical Elemental Cycling model using Redfield and variable DOM stoichiometry corroborate the need for non‐Redfield dynamics to match the observed DOM stoichiometry. From our model simulations, preferential DOP remineralization is found to increase the strength of the biological pump by ~9% versus the case of Redfield DOM cycling. Global net primary productivity increases ~10% including an increase in marine nitrogen fixation of ~26% when preferential DOP remineralization and direct utilization of DOP bymore » phytoplankton are included. The largest increases in marine nitrogen fixation, net primary productivity, and carbon export are observed within the western subtropical gyres, suggesting the lateral transfer of P in the form of DOP from the productive eastern and poleward gyre margins may be important for sustaining these processes downstream in the subtropical gyres.« less

Authors:

Letscher, Robert T. ^[1]; Moore, J. Keith ^[1]

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1. Earth System Science University of California Irvine California USA

Publication Date:

Tue Mar 24 00:00:00 EDT 2015

Sponsoring Org.:

USDOE

OSTI Identifier:

1402350

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Global Biogeochemical Cycles

Additional Journal Information:

Journal Name: Global Biogeochemical Cycles Journal Volume: 29 Journal Issue: 3; Journal ID: ISSN 0886-6236

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English