A Cryptic Sulfur Cycle in Oxygen-Minimum–Zone Waters off the Chilean Coast

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Science  11 Nov 2010:
DOI: 10.1126/science.1196889


Nitrogen cycling is normally thought to dominate the biogeochemistry and microbial ecology of oxygen-minimum zones in marine environments. Through a combination of molecular techniques and process rate measurements, we show that both sulfate reduction and sulfide oxidation contribute to energy flux and elemental cycling in oxygen-free waters off the coast of northern Chile. These processes may have been overlooked because the sulfide produced by sulfate reduction immediately oxidizes back to sulfate. This cryptic sulfur cycle is linked to anammox and other nitrogen cycling processes, suggesting it may influence biogeochemical cycling in the global ocean.