Nitrogen in Past Marine Environments
This chapter reviews the ongoing efforts to use sediment and ice core records to understand the dynamics of oceanic fixed nitrogen (N), focusing on recent glacial-interglacial cycles. Research has, up to this point, followed the reductionist approach of trying to reconstruct either changes in the ocean N budget (largely through low latitude records) or changes in the internal cycling and distribution of N (largely through high latitude records). However, evidence is building for a coupling of high and low latitude changes, connecting the processes that control the distribution of N in the ocean with those that control the size of the whole ocean N inventory. Discussion begins by considering how the nitrogen cycle of times past may have differed from that of today, followed by an overview of how nitrogen cycle features are recorded in marine sediments. It may seem as though the current view of the past marine N-cycle is highly uncertain, but this should be viewed in the context of the last several decades. The first proposition that climate change can influence the marine N-cycle was made and points out that the short residence time of fixed marine N made it a good candidate for change over glacial-interglacial cycles. © 2008 Copyright © 2008 Elsevier Inc. All rights reserved..
Nitrogen in the Marine Environment