Ocean Sciences PhD project 2010

Supervisors: Prof. S. Van den Berg & Dr. P. Salaun

Iron is subject to chemical speciation as a result of redox reactions and interaction with dissolved organic matter. The composition of the natural organic ligands is unknown and much work is carried out towards its identification. Siderophores are thought to play a role in surface waters although even there their concentration is below the concentration required to account for the ligands that have been found to exist at levels of about 1 nmol L-1. Recent work at our laboratory has indicated that humic matter is capable of binding iron more strongly than appreciated, and also that iron-binding humic substances (HS) occur at significant levels in coastal waters (see Figure). A preliminary measurement indicates that deep ocean (Pacific) water contains the equivalent of 1 nM of HS, which would be sufficient to account for all ligands in these waters.