Nitrogen isotopic constraints on nutrient transport to the upper ocean

François Fripiat, Alfredo Martínez-García, Dario Marconi, Sarah E. Fawcett, Sebastian H. Kopf, Victoria H. Luu, Patrick A. Rafter, Run Zhang, Daniel M. Sigman, Gerald H. Haug

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Ocean circulation supplies the surface ocean with the nutrients that fuel global ocean productivity. However, the mechanisms and rates of water and nutrient transport from the deep ocean to the upper ocean are poorly known. Here, we use the nitrogen isotopic composition of nitrate to place observational constraints on nutrient transport from the Southern Ocean surface into the global pycnocline (roughly the upper 1.2 km), as opposed to directly from the deep ocean. We estimate that 62 ± 5% of the pycnocline nitrate and phosphate originate from the Southern Ocean. Mixing, as opposed to advection, accounts for most of the gross nutrient input to the pycnocline. However, in net, mixing carries nutrients away from the pycnocline. Despite the quantitative dominance of mixing in the gross nutrient transport, the nutrient richness of the pycnocline relies on the large-scale advective flow, through which nutrient-rich water is converted to nutrient-poor surface water that eventually flows to the North Atlantic.

Original languageEnglish (US)
Pages (from-to)855-861
Number of pages7
JournalNature Geoscience
Issue number11
StatePublished - Nov 2021

All Science Journal Classification (ASJC) codes

  • General Earth and Planetary Sciences


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