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Impact of Inorganic Particles of Sedimentary Origin on Global Dissolved Iron and Phytoplankton Distribution
Author(s) -
Beghoura H.,
Gorgues T.,
Aumont O.,
Planquette H.F.,
Tagliabue A.,
Auger P.A.
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015119
Subject(s) - phytoplankton , environmental science , biogeochemical cycle , sediment , oceanography , particulates , scavenging , sedimentation , chemical oceanography , environmental chemistry , nutrient , geology , chemistry , microorganism , paleontology , biochemistry , microbial biodegradation , bacteria , antioxidant , organic chemistry
Iron is known to be the limiting nutrient for the phytoplankton growth over ~40% of the global ocean and to impact the structure of marine ecosystems. Dissolved iron (DFe) is assumed to be the only form available to phytoplankton while particulate iron (PFe) has mostly been considered for its role in the biogenic iron remineralization and induced scavenging. Therefore, most studies focused on the nature of DFe external sources to the ocean (i.e., eolian dust, riverine fluxes, hydrothermal sources, and sediment) and their quantification, which still remain uncertain. Among these external sources, the sedimentary sources have been shown to be underestimated. Moreover, the iron supply from sediments has been documented to be often larger in the particle fraction. Here we test the impacts of an iron sediment source of inorganic particulate iron (PFe Inorg ) on global DFe and phytoplankton distribution. We use experimentally acquired knowledge to test a parameterization of a PFe Inorg pool in a global biogeochemical model and compare with published indirect estimation. Depending on the parameterization of its dissolution and sinking speed, the PFe Inorg can noticeably enrich water masses in DFe during its transport from the sediment to the open ocean, notably in regions not usually accessible to external DFe inputs. Indeed, the fact that DFe is prone to scavenging reduces the impact of equivalent Fe inputs from sediments in the dissolved form in those regions far from the sediment sources. PFe Inorg thereby has the potential to fuel the phytoplankton growth in offshore regions impacting the coastal‐offshore chlorophyll gradient.