Untitled - The Future Ocean

cage occupancy) and numerical modeling of liquid CO 2 permeation from the ocean floor intosediments have only recently be started (Sun and Duan 2005, Kang et al. 2005). These disparateapproaches need to be connected and extended to more realistic multicomponent systems.3. Previous and on-going work of the proponentsAt IFM-GEOMAR, several scientists are involved in the assessment of the marine carbon system,including the uptake of anthropogenic CO 2 , and are playing a leading role within the EU IntegratedProject CARBOOCEAN which focuses on the ocean’s ability to sequester CO 2 . This role includeshigh pressure laboratory investigations to understand the kinetics of phase transitions betweenliquid CO 2 , seawater, and CO 2 clathrates as well as open-ocean in-situ experiments which addressthese key parameters (Rehder et al. 2004, Brewer et al. 2003). Scientists at the CAU’s Institute ofPhysical Chemistry investigate structures and dynamics of clathrates on the molecular leveltheoretically, using quantum chemistry and molecular dynamics. Present expertise in the group ofB. Hartke covers molecular-level simulations, including ab-initio quantum chemistry, force fieldfitting, global structure optimizations and other techniques. Experimental work on the formation ofsolids under hydrothermal conditions is performed in the group of W. Bensch at the Institute ofInorganic Chemistry, using high-end X-ray absorption fine structure (XAFS) techniques for the fluidphases and combined scattering techniques for the bulk solid phases (Michailovski 2005). Thispermits an exact characterization of critical compounds and steps, thus providing indispensableinput for modeling and experiments at larger scales. The Institute of Geosciences is experienced inthe geophysical imaging of sub-sedimentary gas accumulations by acoustic methods and theinvestigation of mechanical properties of clathrate-bearing sediments. This expertise can providesupport for the development of models and monitoring strategies for disposal sites.4. ObjectivesThe new JRG and proponents of A5 will address the reactions at the CO 2 -seawater-sedimentinterfaces down to the molecular level, with emphasis on the mechanisms and kinetics of thephase transition processes. Models concerning the consequences of CO 2 injection require aproper estimation of the transfer of CO 2 from the condensed into the dissolved state. So far, thisprocess has only been investigated in a limited number of open-ocean and laboratory experimentson the pure CO 2 -seawater system. A proper parameterization in the pressure-temperature domainand a mechanistic understanding of the reactions on a molecular level are lacking. The latter iscrucial for an estimation of the sensitivity of the reaction kinetics to impurities and other (non-CO 2 )hydrate formers, and for the potential discovery of hydrate-stabilizing additives. In addition,reactions with particulate matter under extremely high CO 2 pressures, such as metal adsorptionand chemical weathering have not been evaluated. To promote the understanding of ecologicallyimportant processes for various CO 2 deposition scenarios, the group will use methods includingmolecular dynamic modeling, advanced spectroscopy, and high pressure experimental simulationsof oceanic in-situ conditions. The head of the JRG is expected to be specialist in at least one ofthese fields, and to comprehensively address the problem within the JRG and by collaboration with51