Studies to Improve the Oceanic Germanium Mass Balance

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The ratio of Ge/Si in biogenic opal has enormous potential as a tracer of the balance between chemical fluxes from continental weathering and hydrothermal sources and as a tracer of oceanic processes such as productivity. However, the degree to which this tracer can be successfully applied to these problems critically depends on the mass-balance of the Ge-Si system and the chemical behavior of these two elements in the oceans. It appears that the current understanding of the Ge-Si system is incomplete since estimates of the hydrothermal Si flux based on the Ge-Si system are much less than fluxes estimated from other tracers or models. The difficulty with current models of the Ge-Si system is that they do not account for the probability that the marine geochemical cycle for the Ge includes significant sinks other than biogenic opal. A series of experiments will be conducted to evaluate the flux of oceanic Ge to nonbiogenic sediment components. The Ge content and key Ge/element ratios will be characterized in eolian source materials as well as in North Pacific pelagic sediments. The results should provide important constraints on the accumulation rate of nonbiogenic Ge in the oxic pelagic environment.