View Abstract

MODEL EVALUATIONS OF PORE WATER IRON ISOTOPE SIGNATURES IN THE SOUTH ATLANTIC OCEAN - IMPLICATIONS FOR BENTHIC EXCHANGE

In recent decades, seafloor sediments have been discovered to be a major contributor of the dissolved micronutrient iron (Fe) to the ocean, sustaining oceanic primary production and carbon export. Quantifying this input and understanding what controls it is urgently required for more accurate simulations of past and future ocean conditions and climate. In this presentation, we will recall our empirical basis for incorporating benthic Fe fluxes into ocean models, followed by recent isotopic evidence for an additional, ill-quantified and unaccounted for ‘non-reductive dissolution’ (NRD) process/processes, which also release Fe from sediments to the ocean. We present dissolved Fe isotope compositions in surface sediment pore waters from across the South Atlantic Ocean (GEOTRACES A10), and show that they are consistently similar to average igneous rocks in the oxidizing layers (δ56Fe = +0.16±0.9 ‰, relative to IRMM-14, n = 16), and partitioned into soluble and colloidal fractions. We use a combined pore water modelling and isotopic mass-balance approach, to consider the mechanisms responsible for controlling the apparent dissolution of Fe in oxidizing layers, and further offer a quantification of benthic Fe fluxes attributed to NRD.

Authors

Homoky, W. B., University of Oxford, United Kingdom, will.homoky@earth.ox.ac.uk

Conway, T. M., University of South Florida, USA, conway.tm@gmail.com

John, S. G., University of Southern California, USA, sethjohn@usc.edu

Woodward, E. M., Plymouth Marine Laboratory, United Kingdom, EMSW@pml.ac.uk

Mills, R. A., University of Southampton, United Kingdom, Rachel.Mills@soton.ac.uk

Details

Oral presentation

Session #:082
Date: 02/28/2017
Time: 17:15
Location: 306 B

Presentation is given by student: No