Report

Microbial sulfate reduction and organic sulfur formation in sinking marine particles

See allHide authors and affiliations

Science  08 Jan 2021:
Vol. 371, Issue 6525, pp. 178-181
DOI: 10.1126/science.abc6035

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

Where they can't breathe

Climate warming is causing the expansion of marine oxygen-deficient zones, which are regions in which dissolved oxygen concentrations are so low that many marine animals cannot survive. This phenomenon also might affect the global cycles of carbon, sulfur, nitrogen, and trace metals in the oceans. Raven et al. show how ocean anoxia affects microbial sulfur processing in sinking marine particles. They observed cryptic microbial sulfate reduction, which forms organic sulfur that is resistant to acid hydrolysis, a process that could enhance carbon preservation in sediments underlying oxygen-deficient water columns. This may help explain some of the more extreme episodes of organic carbon preservation associated with marine anoxia in Earth's history.

Science, this issue p. 178

Abstract

Climate change is driving an expansion of marine oxygen-deficient zones, which may alter the global cycles of carbon, sulfur, nitrogen, and trace metals. Currently, however, we lack a full mechanistic understanding of how oxygen deficiency affects organic carbon cycling and burial. Here, we show that cryptic microbial sulfate reduction occurs in sinking particles from the eastern tropical North Pacific oxygen-deficient zone and that some microbially produced sulfide reacts rapidly to form organic sulfur that is resistant to acid hydrolysis. Particle-hosted sulfurization could enhance carbon preservation in sediments underlying oxygen-deficient water columns and serve as a stabilizing feedback between expanding anoxic zones and atmospheric carbon dioxide. A similar mechanism may help explain more-extreme instances of organic carbon preservation associated with marine anoxia in Earth history.

View Full Text

Stay Connected to Science