G02_P01

Radiocarbon geochemistry of amino acids in marine sediments

Blattmann T^1,2,  Ishikawa N², Keil R³, Yokoyama Y⁴, Ogawa N², Haghipour N^1,5, Sun Y^2,4,6, Neibauer J³, Duffy M³, Suga H², Miyairi Y⁴, Eglinton T¹, Takano Y², Ohkouchi N²

¹ETH Zurich, Zurich, Switzerland, ²Biogeochemistry Research Center, JAMSTEC, Yokosuka, Japan, ³School of Oceanography, Seattle, USA, ⁴Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan, ⁵Laboratory of Ion Beam Physics, ETH Zurich, Zurich, Switzerland, ⁶Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan

The “building blocks of life” occur ubiquitously on Earth’s surface in the form of proteins, peptides, and single amino acids. To shed light on amino acid sources, cycling, and preservation, we have conducted amino acid-specific radiocarbon analysis on surficial marine sediment from the North American west coast. As the main goal for these investigations, we test a hypothesis that amino acid-specific radiocarbon signatures reflect the interactions of organic matter with mineral surfaces on a molecular level. This hypothesis was inspired by laboratory-based sorption experiments showing strong differences in the partitioning of different amino acids between dissolved and clay mineral adsorbed states (Blattmann & Ishikawa, 2020). We employed high-performance liquid chromatography described in Blattmann et al. (2020) to isolate individual amino acids extracted from marine sediment which were vetted for their purity via chromatography and elemental composition. Isolated amino acids were measured on accelerator mass spectrometers as gas and graphite samples at ETH Zurich and the University of Tokyo, respectively. Amino acids showed multiple centuries age difference demonstrating differential turnover within this compound class in marine surface sediments. The results highlight the role of clay minerals in modulating the preservation of amino acids in the sedimentary record.

References:

Blattmann, T.M. & Ishikawa, N.F. (2020) Theoretical amino acid-specific radiocarbon content in the environment: Hypotheses to be tested and opportunities to be taken. Frontiers in Marine Science 7.

Blattmann, T.M. et al. (2020) Liquid chromatographic isolation of individual amino acids extracted from sediments for radiocarbon analysis. Frontiers in Marine Science 7.