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Global patterns of surface ocean dissolved organic matter stoichiometry
  • Zhou Liang,
  • Robert T. Letscher,
  • Angela N Knapp
Zhou Liang
Florida State University

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Robert T. Letscher
University of Hampshire
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Angela N Knapp
Florida State University
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Surface ocean marine dissolved organic matter (DOM) serves as an important reservoir of carbon (C), nitrogen (N), and phosphorus (P) in the global ocean, and is produced and consumed by both autotrophic and heterotrophic communities. While prior work has described distributions of dissolved organic carbon (DOC) and nitrogen (DON) concentrations, our understanding of DOC:DON:DOP stoichiometry in the global surface ocean has been limited by the availability of DOP concentration measurements. Here we estimate mean surface ocean bulk and labile DOC:DON:DOP stoichiometry in biogeochemically and geographically defined regions, using newly available marine DOM concentration databases. Global mean surface ocean bulk (C:N:P = 387:26:1) and labile (C:N:P = 179:20:1) DOM stoichiometries are higher than Redfield stoichiometry, with labile DOM stoichiometry similar to that of global mean surface ocean particulate organic matter (C:N:P = 160:21:1) reported in a recent compilation. DOM stoichiometry varies across ocean basins, ranging from 251:17:1 to 638:43:1 for bulk and 83:15:1 to 414:49:1 for labile DOM C:N:P, respectively. Surface ocean DOP exhibits larger relative changes than DOC and DON, driving surface ocean gradients in DOC:DON:DOP stoichiometry. Inferred autotrophic consumption of DOP helps explain intra- and inter-basin patterns of marine DOM C:N:P stoichiometry, with regional patterns of water column denitrification and iron supply influencing the biogeochemical conditions favoring DOP use as an organic nutrient. Specifically, surface ocean marine DOM exhibits increasingly P-depleted stoichiometries from east to west in the Pacific and from south to north in the Atlantic consistent with patterns of increasing P stress and alleviated iron stress, respectively.
30 Mar 2023Submitted to ESS Open Archive
04 Apr 2023Published in ESS Open Archive