Abstract

Iron is an essential micronutrient for marine phytoplankton. Its low availability in the upper ocean has been made responsible for the high-nitrate low-chlorophyll (HNLC) conditions in some ocean regions. One of the main external iron sources is dust deposition which is spatially and temporally variable and affected by climate change.

In this talk, I first introduce the result from our recent modelling study on the role of dust particles in the iron cycle. In high deposition regions such as the tropical and subtropical Atlantic Ocean, dust is the most important iron source. On the other hand, it is also a source of particle surface for iron adsorption, removing iron from the dissolved pool. We studied this double role of lithogenic material in the marine iron cycle by adding a new scheme for describing particle dynamics into a global biogeochemistry and ecosystem model, including particle aggregation and disaggregation of two particle size classes, as well as iron adsorption on both organic and lithogenic particles. Considering the additional adsorption of iron on lithogenic particles, the modelled dissolved iron concentration is reduced significantly in the tropical and subtropical Atlantic, bringing the model much closer to observations.

Models with high complexity are always accompanied by high uncertainty. In the second part of my talk, I use our study on the role of variable organic iron-binding ligands in the iron cycle as an example to explain how modellers infer parameter values from laboratory experiments and field observations and deal with the unconstrained processes.

At the end of the talk I give an overview of our future work.

CV

08.2014-Present  PostDoctoral researcher, Alfred Wegener Institute

08.2014-03.2015 Assistant lecturer, RWTH Aachen

02.2011-12.2011 PostDoctoral researcher, Alfred Wegener Institute

07.2007-01.2011 PhD, Alfred Wegener Institute

10.2001-03.2007 B.Sc. and M.Sc., Albert-Ludwigs-Universitat Freiburg

Research interests

- Global biogeochemical modelling of iron and other trace metals

- Cycling of biogenic and lithogenic particles

- Feedbacks between climate and the biogeochemical cycle of iron and silicon