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Slowly Sinking Particles Underlie Dissolved Iron Transport Across the Pacific Ocean
Author(s) -
Misumi K.,
Nishioka J.,
Obata H.,
Tsumune D.,
Tsubono T.,
Long M. C.,
Lindsay K.,
Moore J. K.
Publication year - 2021
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 - 10.1029/2020gb006823
Subject(s) - isopycnal , biogeochemical cycle , oceanography , geology , sedimentary rock , continental shelf , biogeochemistry , oceanic basin , water mass , geotraces , flux (metallurgy) , pelagic zone , structural basin , transect , paleontology , chemistry , environmental chemistry , organic chemistry
Continental shelf sediments are an important source of iron (Fe) in the oceans. Observational data suggest that basin‐scale transport of sedimentary sourced Fe accompanies the ventilation of the intermediate layer in the North Pacific. Here we use a marine biogeochemical model to explore the Fe transport mechanism with a focus on the role of sinking particles. The lateral penetration of sedimentary sourced Fe was best simulated when we assumed a short desorption and disaggregation length scale of Fe from sinking particles. The simulation results indicated that Fe is laterally transported mainly through interactions with particles with sinking velocities of 180–460 m yr −1 ; these velocities are two orders of magnitude slower than typical sinking rates of marine aggregates determined from mass flux measurements. Slowly sinking particles drive the basin‐scale transport of Fe by prolonging its residence time and by injecting sedimentary sourced Fe supplied originally to less dense waters into the intermediate layer water across isopycnal surfaces. A large amount of Fe from shelf sediments of the Okhotsk and Bering Seas is exported to the North Pacific through this particle interaction. These results highlight a biogeochemical linkage between the marginal seas and ocean basins that has been overlooked in global ocean models.