Nitrogen and Carbon Isotope Paleo-Proxy Verification in the Southern Ocean

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Over the last decade, several new deep-sea sediment proxies for important oceanic properties have been proposed and developed to varying degrees. An urgent need has been recognized, though, for verification and calibration studies, particularly in the Southern Ocean. This proposal focuses on sedimentary 15N/14N ( 15N) and organic 13C/12C ( 13C org), both of which have been shown in core top and surface ocean studies to exhibit large north/south gradients in the modern Southern Ocean. Within the JGOFS study region in the Pacific Sector of the Southern Ocean this research team will: 1) Confirm and calibrate the relationships between NO3 utilization and 13C in surface waters. 2) Determine the fidelity of transfer of the proxy signal to the seafloor. 3) Determine the magnitude and consistency of any diagenetic effects in the preservation of the proxy signals in the sediments and identify sedimentary fractions for which diagenetic effects are minimized. Measurements will be made on samples collected seasonally between the subtropical convergence and Ross Sea.