Award: OCE-1536506

The Arctic ecosystem including carbon-rich watersheds, productive coastal shelves and open waters are increasingly vulnerable to climate change with global consequences. Our research was focused on learning more about the reactivity and fate of the enormous amounts of organic matter delivered to the Arctic Ocean by large rivers. To this end we developed a new forensic tool to study the movements and reactions of land-derived organic matter. The tool relied on the measurement of chemical compounds that are unique to vascular plants. For the development of the new method we used field samples collected along the Texas coast, explored various digestion reactions and employed state-of-the-art analytical equipment to achieve the sensitivity needed to work in open ocean environments. Once the new method was developed and validated, we analyzed samples that were collected with a team of scientists on a cruise on the German icebreaker Polarstern across the Arctic Ocean from the Nansen Basin into the Amundsen and Makarov basins. The team of scientists onboard measured a large number of environmental variables allowing the interpretation of our results in a holistic environmental context and emphasizing the efficient, collaborative nature of polar research. We found that land-derived organic matter was rapidly removed within the Arctic Ocean primarily through the oxidation by microbial organisms. Freeze/thawing processes moved dissolved organic matter from surface waters to deeper layers providing an additional oceanographic tracer for studying water mass formation along the vast shelf areas and the central Arctic Ocean. Although the oxidation of dissolved land-derived organic matter to carbon dioxide was extensive during transport, a substantial amount was exported to the North Atlantic through the two main Arctic gateways. In addition to research, our project provided a productive learning environment for undergraduate and graduate students giving them the opportunity to work with modern analytical tools. Findings of the research were published in scientific journals, presented at international meetings and also integrated in lectures for undergraduate and graduate classes. Last Modified: 03/25/2019 Submitted by: Karl Kaiser