Oceanography Seminar

October 3, 3:00pm - 4:15am
Mānoa Campus, Marine Sciences Building 100 Add to Calendar

Joji Uchikawa
Post-Doc Researcher
Department of Oceanography

“Characterizing the B/Ca ratios of synthetic CaCO3 under different carbonate chemistry regimes: Motivations and initial results”

Abstract: The ratio of boron to calcium (B/Ca) in foraminiferal shells is increasingly being applied to estimate past ocean pH and carbonate chemistry. With some assumptions, this proxy may provide a way to reconstruct atmospheric CO2 concentration for time periods beyond the reach of ice core records. But culture and core-top calibrations reveal that foraminiferal B/Ca ratios also show varying degrees of dependence on multiple physical/chemical parameters besides pH (e.g., temperature, salinity, Δ[CO32-] = [CO32-]in situ – [CO32-]Saturation, [B(OH)4]/[HCO3-] ratio, etc.). While many of these parameters co-vary in situ, a given parameter can be disentangled and its effect on B incorporation into CaCO3 can be individually evaluated using inorganic precipitation experiments. This study employs a chemo-stat system to grow synthetic CaCO3 under a variety of carbonate chemistry regimes in order to ground-truth the parameter(s) that ultimately regulate boron partitioning in CaCO3.

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Oceanography, Mānoa Campus

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