Surface Water Iron Deposition Histories and the Initiation of Phytoplankton Blooms in the North Pacific Subtropical Gyre

A large phytoplankton bloom occurred in the central North Pacific Subtropical Gyre (NPSG) from July to October 2022. Input of limiting nutrients for diazotrophy, particularly iron (Fe), may have contributed to the bloom's initiation. Observations of Fe within the bloom indicate higher than usual aerosol Fe deposition preceding the bloom. Modelled water parcel back‐trajectories with soluble Fe deposition simulations indicate that a large Fe deposition event occurred roughly 1-month before the formation of the bloom. This lag suggests that physical factors preserved the Fe deposition feature long enough in surface waters for diazotrophs to respond to the elevated Fe concentrations. The modelling method developed here is a useful approach for exploring the role of Fe in stimulating marine phytoplankton productivity.

Reference: Kong, K.P., Yang, S.-C., Barone, B., et al. (2026). Surface water iron deposition histories and the initiation of phytoplankton blooms in the North Pacific Subtropical Gyre. Global Biogeochem. Cycles, 40, e2025GB008499. https://doi.org/10.1029/2025GB008499