Carbon-FE - CARBON Fixation and Export in oligotrophic ocean

Endorsed by SOLAS since January 2022


Carbon-FE is a national project funded by the National Natural Science Foundation of China. It selects the North Pacific Subtropical Gyre (NPSG) as the study site to examine carbon fixation and export, or the biological bump in general, regulated by differently sourced nutrients including macronutrients (i.e., N, P, Si) and micronutrients (e.g., Fe). The major objectives are (1) to determine the distribution of macro- and micro-nutrients, fingerprint their sources and estimate their fluxes into the NPSG, (2) to constrain the spatial-temporal variability of biological N2 fixation and its limiting factors in the Nutrient-depleted layer (NDL), (3) to quantify the carbon fixation and associated planktonic community structure, (4) to constrain the export production from both the NDL and Nutrient-repleted layer (NRL), and (5) to simulate the biological pump and carbon sinks in the NPSG.

Schematic of major biogeochemical processes in the euphotic zone of the oligotrophic ocean (middle) and associated gradients in chemical and physical parameters (left). The right panel indicates the five subprojects of this project.
DDN denotes diazotrophic-derived nitrogen.

Find more about Carbob-FE at:

Annual Update

In 2021, the project made substantial progresses including a winter cruise to the subtropical Northwest Pacific from December 2020 to February 2021. Major scientific findings are: 1) The spatial and temporal variability in internal and external sources and fluxes of macro- and micro-nutrients was quantified in the western North Pacific Subtropical Gyre. 2) Iron to nitrogen supply ratio to the surface water was revealed to be an important factor regulating biological nitrogen fixation. 3) Novel algorithms were developed to characterize the light quality and estimate the primary production. 4) Particulate organic cabon export fluxes were overall low but showed a measurable spatial variability; and subregions with different export patterns were identified. 5) A three-dimensional physical-biogeochemical coupled model, Pacific Regional Ocean Model System (ROMS)-Carbon, Silicate, and Nitrogen Ecosystem (CoSiNE)-Iron, was developed including new modules of iron cycle and nitrogen fixation.
To view the full publications in 2021 at