In the past two decades compound-specific isotope analysis of amino acids (CSI-AA) has exploded, moving from a novel analysis performed by a few labs to an increasingly mainstream technique, employed across a steadily increasing range of disciplines from ecology, archaeology, paleoceanography, geomicrobiology, and biogeochemical cycle research. Amino acid stable carbon (d¹³C_AA) and nitrogen (d¹⁵N_AA) measurements remain the best developed applications, with D/H ratios of AA  and molecular position-specific isotopes representing the next frontier. Most work to date has focused on establishing trophic connectivity and baseline isotope values in modern and Anthropocene ecological applications.  However, CSI-AA also has enormous potential for paleo studies. A wide range of d¹⁵N_AA and d¹³C_AA proxies have now been adapted for reconstruction of past N and C cycles, including primary production assemblages, nutrient and export production isotope values.  When coupled with appropriate archives, these approaches represent an entirely new suite of paleo-tools, based on the most abundant class of nitrogenous molecules in well preserved organic material, and offering information about specific processes far beyond common bulk stable isotope records. This talk will present an overview CSI-AA techniques and potential applications, focused primarily on d¹³C_AA and d¹⁵N_AAapplications in paleo-archives, fossils, and microfossils, for reconstructing the ocean N cycle progressively farther back in time.  It will ask how far the past it may be possible to apply this approach, in the face of organic diagenesis and degradation.

Date & Time: Tue Mar 14 2023 11:00:00 GMT+0100 (Central European Standard Time)
Room: Tour 45/55 4eme étage piece 417, https://cnrs.zoom.us/j/92825050021?pwd=cG1vbUtFZFoxT083V2JYNndDeDdiQT09