Basin-scale variations of particulate organic matter stoichiometry in the global ocean

Yang Xiang and Phoebe J Lam, University of California Santa Cruz, Department of Ocean Sciences, Santa Cruz, CA, United States
The particulate organic matter (POM) stoichiometry is of great importance in global biogeochemical cycles because it reveals connections between the marine carbon, nitrogen, and phosphorus cycles. Indeed, the deviation from the Redfield ratio has been recently observed (e.g., Martiny et al., 2013) and has potentially significant consequences for processes such as the nitrogen fixation (e.g., Mills and Arrigo, 2010). Here, we present full water column size-fractionated (1-51 𝜇m; >51 𝜇m) POM stoichiometry in various GEOTRACES and non-GEOTRACES cruises in the global ocean. Our preliminary data show that both carbon to phosphorus (C/P) and carbon to nitrogen (C/N) ratios in large size fraction (LSF; >51 𝜇m) particles are significantly higher than in the small size fraction (SSF; 1- 51 𝜇m) (p values< 0.001). Compared to C/N ratios, C/P ratios are more variable not only within the same basin but also among different basins. Further analysis will help disentangle how different oceanographic processes, such as the lateral transport of lithogenic particles, oxygen-deficient zones (ODZ), hydrothermal vents, and atmospheric deposition, influence the particulate organic matter stoichiometry. This work contributes valuable data to the global dataset of elemental stoichiometry (Martiny et al., 2014), especially in the Arctic Ocean and South Pacific.