The biogeochemical balance of oceanic nickel cycling

• Published in: Nature geoscience 2022-11, Vol.15 (11), p.906-912
• Main Authors: John, Seth G., Kelly, Rachel L., Bian, Xiaopeng, Fu, Feixue, Smith, M. Isabel, Lanning, Nathan T., Liang, Hengdi, Pasquier, Benoît, Seelen, Emily A., Holzer, Mark, Wasylenki, Laura, Conway, Tim M., Fitzsimmons, Jessica N., Hutchins, David A., Yang, Shun-Chung
• Format: Article
• Language: English
• Subjects: 704/47/4112; 704/829/827; Bioavailability; Biogeochemistry; Biological uptake; Cycles; Depletion; Diatoms; Distribution; Earth and Environmental Science; Earth Sciences; Earth System Sciences; Famine; Geochemistry; Geology; Geophysics/Geodesy; Gyres; Marine invertebrates; Methanogenesis; Modelling; Nickel; Ocean circulation; Oceans; Phytoplankton; Regeneration (biological); Scavenging; Upwelling; Vertical distribution
• ISSN: 1752-0894; 1752-0908
• DOI: 10.1038/s41561-022-01045-7

Nickel is a biologically essential element for marine life, with the potential to influence diverse processes, including methanogenesis, nitrogen uptake and coral health, in both modern and past oceans. However, an incomplete view of oceanic Ni cycling has stymied understanding of how Ni may impact marine life in these modern and ancient oceans. Here we combine data-constrained global biogeochemical circulation modelling with culture experiments and find that Ni in oligotrophic gyres is both chemically and biologically labile and only minimally incorporated into diatom frustules. We then develop a framework for understanding oceanic Ni distributions, and in particular the two dominant features of the global marine Ni distribution: the deep concentration maximum and the residual pool of approximately 2 nM Ni in subtropical gyres. We suggest that slow depletion of Ni relative to macronutrients in upwelling regions can explain the residual Ni pool, and reversible scavenging or slower regeneration of Ni compared with macronutrients contributes to the distinct Ni vertical distribution. The strength of these controls may have varied in the past ocean, impacting Ni bioavailability and setting a fine balance between Ni feast and famine for phytoplankton, with implications for both ocean chemistry and climate state. Biological uptake in the surface and release in the deep ocean contribute to oceanic nickel distribution, including the residual surface Ni pool, according to culture experiments, field data and global biogeochemical circulation modelling