Interactions between climate and the marine nitrogen cycle on glacial-interglacial timescales ...

• Main Author: Galbraith, Eric Douglas
• Format: Text
• Language: English
• Published: University of British Columbia 2010
• Subjects: Subarctic
• Online Access: https://dx.doi.org/10.14288/1.0052385; https://doi.library.ubc.ca/10.14288/1.0052385

Nitrogen is a principal component of living organisms and comprises the majority of the atmosphere, yet the scarcity of biologically reactive nitrogen in the ocean limits growth and appears to have varied with past changes in physical climate. This thesis takes a multi-faceted approach, including fine-scale sediment analysis, modern field observations and global numerical modeling, to contribute an integrated view of the marine nitrogen cycle and its climatic sensitivity. Nitrogen bound in diatom frustules, extracted from laminated sediments of the Guaymas Basin, has greater seasonal δ¹⁵N variability than corresponding bulk sediment. Downslope transport of frustules from the shelf contributes δ¹⁵N -depleted nitrogen, while pelagic diatom frustules display great sensitivity to seasonal growing conditions. Bulk sedimentary δ¹⁵N represents a reliable integrated monitor of the local nitrogen substrate. Records of bulk sedimentary δ¹⁵N from the subarctic Pacific reflect the tripartite imprints of diagenesis, ...