Nanoparticles, Colloids and their relationship to Titanium, Aluminium and Iron solubility in the Open Ocean

• Applicant: Dr. Peter Leslie Croot
• Subject Area: Oceanography
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 54760597

We propose here to investigate in detail the marine biogeochemistry of three major crustal elements, Al, Fe and Ti which are major constituents of atmospheric dust deposited to the ocean. All 3 elements are strongly hydrolysed in seawater resulting in low solubilities and high particle reactivity resulting in low concentrations in open ocean seawater (Al: 0.3 - 90 nM, Fe: 50 - 2000 pM, Ti: 3- 300 pM). While presently there is a strong focus on the biogeochemistry of iron, there has been little work performed on Al and even less on Ti. The PI has recently developed two new voltammetric speciation techniques for Ti and Al that allow for the first time an examination of the in situ speciation and reaction kinetics of Ti and Al in open ocean seawater. The proposed work is based around a series of cruises in the Atlantic and Southern Ocean, where soluble (x < 10 kDa), colloidal (10 kDa < x < 0.2 um) and particulate (x >0.2 um) concentrations of these metals will be measured. Laboratory investigations will focus on the solubility of these elements in seawater; this is particularly important with regard to Ti, where no reliable data exist for seawater, and for all the 3 metals in understanding the transport of these metals in the Deep Ocean and supply to surface waters by upwelling and diffusion.

• DFG Programme: Research Grants