Global niche of marine anaerobic metabolisms expanded by particle microenvironments

Daniele Bianchi, Thomas S. Weber, Rainer Kiko, Curtis Deutsch

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

In ocean waters, anaerobic microbial respiration should be confined to the anoxic waters found in coastal regions and tropical oxygen minimum zones, where it is energetically favourable. However, recent molecular and geochemical evidence has pointed to a much broader distribution of denitrifying and sulfate-reducing microbes. Anaerobic metabolisms are thought to thrive in microenvironments that develop inside sinking organic aggregates, but the global distribution and geochemical significance of these microenvironments is poorly understood. Here, we develop a new size-resolved particle model to predict anaerobic respiration from aggregate properties and seawater chemistry. Constrained by observations of the size spectrum of sinking particles, the model predicts that denitrification and sulfate reduction can be sustained throughout vast, hypoxic expanses of the ocean, and could explain the trace metal enrichment observed in particles due to sulfide precipitation. Globally, the expansion of the anaerobic niche due to particle microenvironments doubles the rate of water column denitrification compared with estimates based on anoxic zones alone, and changes the sensitivity of the marine nitrogen cycle to deoxygenation in a warming climate.

Original languageEnglish (US)
Pages (from-to)1-6
Number of pages6
JournalNature Geoscience
DOIs
StateAccepted/In press - Mar 19 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences(all)

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