The influence of dissolved organic matter on the marine production of carbonyl sulfide (OCS) and carbon disulfide (CS2) in the Peruvian upwelling.

Lennartz, Sinikka T. , von Hobe, Marc , Booge, Dennis, Bittig, Henry , Fischer, Tim , Goncalves-Araujo, Rafael, Ksionzek, Kerstin B., Koch, Boris P. , Bracher, Astrid , Röttgers, Rüdiger, Quack, Birgit and Marandino, Christa A. (2019) The influence of dissolved organic matter on the marine production of carbonyl sulfide (OCS) and carbon disulfide (CS2) in the Peruvian upwelling. Open Access Ocean Science, 15 . pp. 1071-1090. DOI 10.5194/os-15-1071-2019.

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Abstract

Oceanic emissions of the climate-relevant trace gases carbonyl sulfide (OCS) and carbon disulfide (CS2) are a major source to their atmospheric budget. Their current and future emission estimates are still uncertain due to incomplete process understanding and therefore inexact quantification across different biogeochemical regimes. Here we present the first concurrent measurements of both gases together with related fractions of the dissolved organic matter (DOM) pool, i.e., solid-phase extractable dissolved organic sulfur (DOSSPE, n=24, 0.16±0.04 µmol L−1), chromophoric (CDOM, n=76, 0.152±0.03), and fluorescent dissolved organic matter (FDOM, n=35), from the Peruvian upwelling region (Guayaquil, Ecuador to Antofagasta, Chile, October 2015). OCS was measured continuously with an equilibrator connected to an off-axis integrated cavity output spectrometer at the surface (29.8±19.8 pmol L−1) and at four profiles ranging down to 136 m. CS2 was measured at the surface (n=143, 17.8±9.0 pmol L−1) and below, ranging down to 1000 m (24 profiles). These observations were used to estimate in situ production rates and identify their drivers. We find different limiting factors of marine photoproduction: while OCS production is limited by the humic-like DOM fraction that can act as a photosensitizer, high CS2 production coincides with high DOSSPE concentration. Quantifying OCS photoproduction using a specific humic-like FDOM component as proxy, together with an updated parameterization for dark production, improves agreement with observations in a 1-D biogeochemical model. Our results will help to better predict oceanic concentrations and emissions of both gases on regional and, potentially, global scales.

Document Type: Article
Research affiliation: MARUM
FZJ
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
HZG
AWI
IOW
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/os-15-1071-2019
ISSN: 1812-0784
Projects: ASTRA-OMZ, ROMIC THREAT, ROMIC SPITFIRE, SOPRAN, The Ocean in the Earth System, Future Ocean
Expeditions/Models/Experiments:
Date Deposited: 01 Mar 2019 14:47
Last Modified: 01 Oct 2019 13:41
URI: http://oceanrep.geomar.de/id/eprint/45953

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