Wednesday 12/07: Kourtney Higgins PhD Proposal Defense

Investigating Biogeochemical Cycling Changes in the Northwestern Hawaiian Islands Using Deep-Sea Corals

Presenter: Kourtney Higgins
Time: Wednesday, 7 December 2022, 1:00 p.m.
Location: 712 O&M Building

Abstract: This dissertation research utilizes both stable and radiogenic isotopic measurements in proteinaceous and scleractinian deep-sea corals to investigate changes in nutrient export and intermediate water variability within the Northwestern Hawaiian Islands. Previous studies have used deep-sea corals to reconstruct primary productivity change. However, little is known about the spatial heterogeneity of the region in a modern context. Further, these deep-sea corals can be used to extend our knowledge of source primary production and water mass histories back several millennia. Proposed techniques for this project are relatively new but have the potential to provide additional oceanographic information about this region given its importance in biogeochemical cycling and climate science.

N* is a tracer for nitrogen fixation and denitrification, where N-fixation is represented by positive values and denitrification in negative values. N* is determined by equation N* = N - 16P + 2.9 from Deutsch et al. (2001), where N- Nitrate and P- Phosphate. Data was collected from World Ocean Atlas 2018 and plotted in Ocean Data View.

Reference:

Deutsch, C., N. Gruber, R. M. Key, J. L. Sarmiento, and A. Ganachaud, 2001: Denitrification and N₂ fixation in the Pacific Ocean. Global Biogeochemical Cycles, 15(2), 483-506, doi:10.1029/2000GB001291.