Unveiling Arctic Organic Carbon Cycling Through Amino Acid Radiocarbon Activity: Implications for Paleoclimatic Reconstruction

Constraining the provenance and ultimate fate of sedimentary organic carbon (OC) in the Arctic remains a fundamental challenge, primarily due to the lack of dependable chronological tools. In this study, we turned to total hydrolyzable amino acids (THAAs)- which decompose preferentially during early diagenesis, leaving behind a residual fraction in sediments that predominantly reflects contemporary marine production- and used their radiocarbon ages as a chronological tool. We applied this approach to core R14 from the Chukchi Plateau and obtained a continuous age framework covering the last deglaciation. The resulting chronology was consistent with previously published Marine Isotope Stage records, confirming the reliability of the method. Importantly, THAAs ¹⁴C dating not only provided direct age estimates for biologically derived OC, but also revealed marked differences in the “pre-depositional” ages among various organic components. During the marine transgression, both total OC (TOC) and humic acids yielded substantially older ages, pointing to intensified coastal erosion as the main driver. In contrast, lipids displayed systematically younger ages, with their timing coinciding with the Younger Dryas and Bering Strait opening. The acid-base insoluble organic matter, on the other hand, reached its minimum age in the mid-Holocene, a period when enhanced marine productivity likely supplied younger organic matter to the seafloor. Collectively, these findings demonstrate that THAAs ¹⁴C dating offers a robust pathway for building reliable sediment chronologies in the Arctic, and they underscore that the intrinsic reactivity of different compound classes fundamentally controls how OC is cycled and ultimately buried across major climatic transitions.