Ge/Si-Opal and the "Missing Sink"-Investigation of Germanium Geochemistry and Paleoredox

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ABSTRACT FROELICH / 9811199 The PI proposes to continue his studies into the geochemical cycling of germanium and silica in the ocean, and the interpretation of Ge/Si-opal records in sediment cores. The two major goals of this proposal are to: 1) use pore water and sediment analyses of Ge to study the diagenetic behavior of Ge, and 2) test the hypothesis that Ge and Si are not fractionated during biouptake. The samples to be analyzed under this proposal represent a unique set of marine sediment, pore water, sediment trap materials, which have been collected by the PI on recent cruises. This proposal provides the opportunity to close the Ge balance in the oceans, since diagenetic reactions in the suboxic zone may represent a non-opal "missing Ge-sink" needed to balance the opal, fluvial and hydrothermal Ge/Si cycle in the ocean. These results will permit a better interpretation of the marine sediment Ge/Si-opal and opal accumulation records, and thus provide a deeper understanding of the interactions among climate change, ocean chemistry and paleoproductivity.