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Redox processes impacting the flux of iron(II) from shelf sediments to the OMZ along the Peruvian shelf

Citation

Croot, PL and Heller, MI and Wuttig, K, Redox processes impacting the flux of iron(II) from shelf sediments to the OMZ along the Peruvian shelf, ACS Earth and Space Chemistry, 3, (4) pp. 537-549. ISSN 2472-3452 (2019) [Refereed Article]


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Copyright 2019 American Chemical Society

DOI: doi:10.1021/acsearthspacechem.8b00203

Abstract

Iron (Fe) is a limiting nutrient in many regions of the open ocean and can also play a key role in controlling primary productivity in Eastern Boundary Upwelling Systems (EBUS). In EBUS regions, where intense oxygen minimum zones (OMZs) contact the continental shelf, significant iron inputs can result from the supply of Fe(II) from reducing sediments. How much of this iron makes it to the photic zone depends on physical processes mixing over different time scales (minutes to decades) and the kinetics of redox and complexation processes impacting the biogeochemical cycling of iron. In this work we examine the controls on Fe(II) release from shelf sediments across the Peruvian OMZ by measuring Fe(II) and hydrogen peroxide (H2O2) in the water column and benthic boundary layer (BBL) and applying a simple 1D mixing model, with either 1 or 2 layers, where the flux of Fe(II) to the water column is treated as analogous to radon, that the decay rate is constant within the mixing layer. Our modeling approach then allows us to compare our estimated decay rate against published oxidation rates for specific oxidants of Fe(II) in OMZ waters and check the validity of our approach. Our data indicate that throughout the OMZ, Fe(II) decay rates may be partially influenced by H2O2, but it is most likely that nitrate-dependent anaerobic Fe(II) oxidizing (NDFO) bacteria are the main oxidizers. In the secondary nitrite maxima (SNM), abiotic NO2 or biotic-mediated processes may also be important. This work highlights the importance and uses of redox species in understanding biogeochemical cycles in the ocean.

Item Details

Item Type:Refereed Article
Keywords:H2O2, ROS, NDFO, nitrite, nitrate, BBL
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Chemical Oceanography
Objective Division:Environment
Objective Group:Other Environment
Objective Field:Marine Oceanic Processes (excl. climate related)
UTAS Author:Wuttig, K (Dr Kathrin Wuttig)
ID Code:130971
Year Published:2019
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2019-02-23
Last Modified:2020-01-07
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