Factors Controlling the Release of Methylated Sulfur Species from Laboratory Mesocosm Experiments in Coastal Seawater
Abstract
The oceans are a dynamic source of volatile organic compounds (VOC) which transfer into the atmosphere where oxidation to low-volatility products may lead to aerosol formation. Dimethyl sulfide (DMS), the dominant marine organosulfur VOC, has been intensively studied because its biogenic emission may be linked to various biogeochemical feedbacks such as cloud albedo. Measurements of other organosulfur compounds (OSCs) are limited in the marine environment due to their high temporal and spatial variability which is largely controlled by biological processes. Here, using an laboratory mesocm, we directly measured the temporal evolution of DMS and other OSC emissions over the course of three phytoplankton blooms. We show that emission of other reduced sulfur gases methanethiol (MeSH) and dimethyl disulfide (DMDS) can rival or even exceed emission of DMS. The emissions of DMS, MeSH, and DMDS exhibit it distinctly different temporal behavior, with MeSH and DMDS emissions peaking after DMS. The differential emissions of these organosulfur species appear linked to the "bacterial switch", whereby the ratio of available dimethylsulfioniopropionate (DMSP) to heterotrophic bacteria influences the partitioning of DMSP catabolism towards lysis or demethiolation. Amplicon sequencing of the bacterial assemblages from each mesocosm revealed select taxa that were found to be correlated with DMS and MeSH emissions. Lastly, a modeling comparison of MeSH and DMDS fluxes to DMS indicate that renewed attention should made to understanding the factors that control the production and consumption of MeSH in marine environments. Particularly in areas where bacterial activity is elevated, MeSH or DMDS fluxes may contribute a significant fraction to the budget of atmospheric sulfate.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A33P2924S
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE