THE NITROGEN CYCLE WITHIN A HIGH LATITUDE OCEAN BASIN (WEDDELL SEA) BEFORE, DURING AND AFTER THE CRETACEOUS/PALEOGENE EXTINCTION EVENT

The processes related to the marine ecosystem recovery in the Weddell Sea after the Cretaceous/Paleogene (K/Pg) extinction event are poorly understood. The goal of this research is to understand the changes within the nitrogen cycle of the Weddell Sea (a high latitude location) before, during and after the K/Pg extinction event. By evaluating the organic nitrogen isotope ratio (δ¹⁵N) fractionation and elemental concentrations from bulk sediment cores retrieved from Maud Rise in the Weddell Sea, we can determine the behavior of the nitrogen cycle processes in the paleoenvironment. Nitrogen fixation and water column denitrification/annamox each have a distinct δ¹⁵N fractionation, which is recorded in the sedimentary rock record, and those processes can be correlated to periods of oxic, suboxic, and anoxic water column conditions. Therefore, our evaluation will provide an explanation of how the nitrogen cycle in the Weddell Sea was affected during the K/Pg extinction event. We anticipate an eventual comparison of our results with the results of similar studies conducted at low and mid latitude locations. This will allow us to better understand the global behavior of the marine nitrogen cycle, as well as water column conditions before, during and after the K/Pg extinction event.