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Ironing Out Fe Residence Time in the Dynamic Upper Ocean
Author(s) -
Black E. E.,
Kienast S. S.,
Lemaitre N.,
Lam P. J.,
Anderson R. F.,
Planquette H.,
Planchon F.,
Buesseler K. O.
Publication year - 2020
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2020gb006592
Subject(s) - residence time (fluid dynamics) , geotraces , iron fertilization , biogeochemical cycle , sediment trap , environmental science , residence , oceanography , cycling , ocean current , climatology , geology , seawater , geography , water column , environmental chemistry , chemistry , phytoplankton , nutrient , demography , geotechnical engineering , organic chemistry , archaeology , sociology
Although iron availability has been shown to limit ocean productivity and influence marine carbon cycling, the rates of processes driving iron's removal and retention in the upper ocean are poorly constrained. Using 234 Th‐ and sediment‐trap data, most of which were collected through international GEOTRACES efforts, we perform an unprecedented observation‐based assessment of iron export from and residence time in the upper ocean. The majority of these new residence time estimates for total iron in the surface ocean (0–250 m) fall between 10 and 100 days. The upper ocean residence time of dissolved iron, on the other hand, varies and cycles on sub‐annual to annual timescales. Collectively, these residence times are shorter than previously thought, and the rates and timescales presented here will contribute to ongoing efforts to integrate iron into global biogeochemical models predicting climate and carbon dioxide sequestration in the ocean in the 21st century and beyond.