Rapid sulfur cycling in sediments from the Peruvian oxygen minimum zone featuring simultaneous sulfate reduction and sulfide oxidation.

Treude, Tina , Hamdan, Leila J., Lemieux, Sydnie, Dale, Andrew W. and Sommer, Stefan (2021) Rapid sulfur cycling in sediments from the Peruvian oxygen minimum zone featuring simultaneous sulfate reduction and sulfide oxidation. Limnology and Oceanography, 66 (7). pp. 2661-2671. DOI 10.1002/lno.11779.

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Supplementary data:

Abstract

Bacterial sulfate reduction (SR) is often determined by radiotracer techniques using 35S‐labeled sulfate. In environments featuring simultaneous sulfide oxidation, SR can be underestimated due to re‐oxidation of 35S‐sulfide. Recycling of 35S‐tracer is expected to be high in sediment with low concentrations of pore‐water sulfide and high abundance of giant filamentous sulfur‐oxidizing bacteria (GFSOB). Here, we applied a sulfide‐spiking method, originally developed for water samples, to sediments along a shelf‐slope transect (72, 128, 243, 752 m water depth) traversing the Peruvian oxygen minimum zone. Sediment spiked with unlabeled sulfide prior to 35S‐sulfate injection to prevent radiotracer recycling was compared to unspiked sediment. At stations characterized by low natural sulfide and abundant GFSOB (128 and 243 m), the method revealed 1–3 times higher SR rates in spiked sediment. Spiking had no effect on SR in sediment with high natural sulfide despite presence of GFSOB (72 m). Bioturbated sediment devoid of GFSOB (752 m) showed elevated SR in spiked samples, likely from artificial introduction of sulfidic conditions. Sulfide oxidation rates at the 128 and 243 m station, derived from the difference in SR between spiked and unspiked sediment, approximated rates of dissimilatory nitrate reduction to ammonium by GFSOB. Gross SR contributed considerably to benthic dissolved inorganic carbon fluxes at the three shallowest station, confirming that SR is an important process for benthic carbon respirations within the oxygen minimum zone. We recommend to further explore the spiking method to capture SR in sediment featuring low sulfide concentrations and high sulfur cycling by GFSOB.

Document Type: Article
Keywords: COASTAL MARINE-SEDIMENTS, ANAEROBIC OXIDATION, METHANE OXIDATION, NITROGEN-FIXATION, ORGANIC-MATTER, NITRATE, MARGIN, QUANTIFICATION, MINERALIZATION, RADIO, TRACER
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > SFB 754
Main POF Topic: PT6: Marine Life
Refereed: Yes
Open Access Journal?: No
Publisher: ASLO (Association for the Sciences of Limnology and Oceanography), Wiley
Related URLs:
Projects: SFB754
Expeditions/Models/Experiments:
Date Deposited: 10 May 2021 06:27
Last Modified: 07 Feb 2024 15:38
URI: https://oceanrep.geomar.de/id/eprint/52566

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