G02_08

Bridging marine biosphere and geosphere using compound-specific radiocarbon analysis of amino acids in fish muscle

Ishikawa N^1,2,  Blattmann T^1,2, Haghipour N², Ogawa N¹, Eglinton T², Ohkouchi N¹

¹Biogeochemistry Research Center, Yokosuka, Japan, ²Geological Institute, Zürich, Switzerland

The Earth surface is a dynamic environment of carbon exchange among different pools. Of these, the linkage between biosphere and geosphere is of key importance for understanding the global carbon cycle. In this presentation, we test a hypothesis that amino acid-specific radiocarbon signatures reflect the exchange of carbon between the marine biosphere and geosphere. To this end, we employed compound-specific radiocarbon analysis of amino acids in fish muscle using High-Performance Liquid Chromatography followed by Elemental-Analyzer Accelerator Mass Spectrometry, which allows us to downsize the final target compounds of > 20 μgC (Ishikawa et al. 2018; Haghipour et al. 2019). Most amino acids did not show Δ¹⁴C values significantly different from those of their expected carbon source (i.e., seawater dissolved inorganic carbon: DIC). However, some amino acids exhibited remarkably low Δ¹⁴C values, suggesting that their carbon skeleton is derived from other carbon sources with signatures different from seawater DIC. The results will not only revise the current picture of carbon cycling in connection with the biosphere, but also open up a new frontier of amino acid biogeochemistry.

References:

Ishikawa, N. F., Itahashi, Y., Blattmann, T. M., Takano, Y., Ogawa, N. O., Yamane, M., Yokoyama, Y., Nagata, T., Yoneda, M., Haghipour, N., Eglinton, T. I., & Ohkouchi, N. (2018). Analytical Chemistry, 90(20), 12035-12041.

Haghipour, N., Ausín, B., Usman, M. O., Ishikawa, N., Wacker, L., Welte, C., Ueda, K., & Eglinton, T. I. (2018). Analytical Chemistry, 91(3), 2042-2049.