Natural forcing of the North Atlantic nitrogen cycle in the Anthropocene

Xingchen Tony Wang, Anne L. Cohen, Victoria Luu, Haojia Ren, Zhan Su, Gerald H. Haug, Daniel Mikhail Sigman

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Human alteration of the global nitrogen cycle intensified over the 1900s. Model simulations suggest that large swaths of the open ocean, including the North Atlantic and the western Pacific, have already been affected by anthropogenic nitrogen through atmospheric transport and deposition. Here we report an ∼130-yearlong record of the 15N/14N of skeleton-bound organic matter in a coral from the outer reef of Bermuda, which provides a test of the hypothesis that anthropogenic atmospheric nitrogen has significantly augmented the nitrogen supply to the open North Atlantic surface ocean. The Bermuda 15N/14N record does not show a longterm decline in the Anthropocene of the amplitude predicted by model simulations or observed in a western Pacific coral 15N/14N record. Rather, the decadal variations in the Bermuda 15N/14N record appear to be driven by the North Atlantic Oscillation, most likely through changes in the formation rate of Subtropical Mode Water. Given that anthropogenic nitrogen emissions have been decreasing in North America since the 1990s, this study suggests that in the coming decades, the open North Atlantic will remain minimally affected by anthropogenic nitrogen deposition.

Original languageEnglish (US)
Pages (from-to)10606-10611
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number42
DOIs
StatePublished - Oct 16 2018

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • Anthropocene
  • Atmospheric deposition
  • Nitrogen cycle
  • North Atlantic

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