Biogeochemical Impact of Iron released by Marine particles of sedimentary and hydrothermal origin – BIIM

BIIM aims to 1) assess the processes leading to the net dissolution of abiotic particulate iron from sedimentary and hydrothermal origin, and 2) evaluate its impact on marine biogeochemistry. This is a crucial topic, as dissolved iron controls marine biological productivity and carbon sequestration in over 30% of the global ocean. Abiotic particulate iron has been up to now considered as refractory material. Recent observations question this assumption and suggest that this iron pool may be prone to dissolution. However, the exchange mechanisms between the particulate and dissolved pools of iron have only been superficially identified and quantified.
Laboratory experiments will be inspired from the modellers’ needs and will assess the dissolution rates of particles from different compositions and origins as a function of environmental factors such as temperature, light levels, or concentrations of organic ligands. These controlling factors are needed by the modellers in the perspective of a global modeling of abiotic particulate iron. The key processes identified during the laboratory experiments will then be modelled using simple 0D models, based on mathematical relationships inferred during these experiments. The parameters values will be obtained by approaching the best possible fit between the model results and the outcome of the laboratory experiments. Finally, abiotic particulate iron cycle, derived from the 0D models, will be added to the three-dimensional global ocean model NEMO-PISCES which, for now, only considers sedimentary and hydrothermal dissolved iron source. This 3D model exercise will allow assessing the potential impact of the abiotic particulate iron on the biogeochemical cycles and in particular, but not restricted to, the carbon cycle.
This project relies on a strong collaborative effort between modelers and observationalists. BIIM will also allow the PI, hired at CNRS in 2014, to further develop her research and to gather a community on the emerging and pivotal topic of particulate trace metals.