230Th dynamics in the Eastern Equatorial Pacific Ocean: testing the 230Th-normalization method to estimate sediment fluxes

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Understanding the behavior of 230Th is critical to interpret the sedimentary record and understand how climate change affects oceanographic processes. This study will address the controversy in using this technique based on assumptions made in the 230Th model. Specifically, the PIs will address the issue of how one explains sedimentary 230Th inventories along the equator in the Pacific that are larger than those expected from a constant water column production rate. They will compare the assumption that the flux of laterally advected sediment can surpass the vertically rained flux by up to 2-4 times versus the argument that mass accumulation rates are affected by 230Th mobility and lateral transport of 230Th from the central Pacific gyres. This project teams up PIs who have reached different conclusions about this question. The award supports a research cruise that will collect water column, sediment trap, and sediment (low-flux red-clay environments) to determine if significant 230Th transport might occur out of the region. The award also supports education and training of a graduate student for three years, and the cruise will include sea-going experience for both graduate and undergraduate students.