Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates
<p>As the sea surface microlayer (SML) is the uppermost oceanic layer and differs in biogeochemical composition to the underlying subsurface water (SSW), it is important to determine whether processes in the SML modulate gas exchange, particularly for climate active gases. Enrichment of dimeth...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-10-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/18/1559/2022/os-18-1559-2022.pdf |
| _version_ | 1798044268374261760 |
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| author | A. D. Saint-Macary A. D. Saint-Macary A. Marriner S. Deppeler K. A. Safi C. S. Law C. S. Law |
| author_facet | A. D. Saint-Macary A. D. Saint-Macary A. Marriner S. Deppeler K. A. Safi C. S. Law C. S. Law |
| author_sort | A. D. Saint-Macary |
| collection | DOAJ |
| description | <p>As the sea surface microlayer (SML) is the uppermost
oceanic layer and differs in biogeochemical composition to the underlying
subsurface water (SSW), it is important to determine whether processes in
the SML modulate gas exchange, particularly for climate active gases.
Enrichment of dimethyl sulfide (DMS) and its precursor
dimethylsulfoniopropionate (DMSP) has been reported in the SML, but it
remains unclear how this is maintained whilst DMS is lost to the atmosphere.
To examine this, a comprehensive study of DMS source and sink processes,
including production, consumption, and net response to irradiance, was
carried out in deck-board incubations of SML water at five locations in
different water masses in the southwestern Pacific east of New Zealand. Net
consumption of DMSP and production of DMS in the light and dark occurred at
all sites. The net response of DMS and DMSP to irradiance varied between
stations but was always lower than conversion of DMSP to DMS in the dark. In
addition, DMS photolytic turnover was slower than reported elsewhere, which
was unexpected given the high light exposure in the SML incubations. Although no
relationships were apparent between DMS process rates and biogeochemical
variables, including chlorophyll <span class="inline-formula"><i>a</i></span>, bacteria, and phytoplankton groups, net
bacterial DMSP consumption was correlated with DMSP and DMS concentrations
and also dinoflagellate and <i>Gymnodinium</i> spp. biomass, supporting the findings of a
companion study that dinoflagellates play an important role in DMS cycling
in the SML. However, net DMS production rates and accumulation were low
relative to regional air–sea DMS loss, indicating that
DMS cycling within the SML is unlikely to influence regional DMS
emissions.</p> |
| first_indexed | 2024-04-11T23:01:04Z |
| format | Article |
| id | doaj.art-bc103be019154e2d806ddc2c59b321a9 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-04-11T23:01:04Z |
| publishDate | 2022-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-bc103be019154e2d806ddc2c59b321a92022-12-22T03:58:12ZengCopernicus PublicationsOcean Science1812-07841812-07922022-10-01181559157110.5194/os-18-1559-2022Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and ratesA. D. Saint-Macary0A. D. Saint-Macary1A. Marriner2S. Deppeler3K. A. Safi4C. S. Law5C. S. Law6National Institute of Water and Atmospheric research, Wellington, 6021, New ZealandDepartment of Marine Science, University of Otago, Dunedin, 9016, New ZealandNational Institute of Water and Atmospheric research, Wellington, 6021, New ZealandNational Institute of Water and Atmospheric research, Wellington, 6021, New ZealandNational Institute of Water and Atmospheric Research, Hamilton, 3216, New ZealandNational Institute of Water and Atmospheric research, Wellington, 6021, New ZealandDepartment of Marine Science, University of Otago, Dunedin, 9016, New Zealand<p>As the sea surface microlayer (SML) is the uppermost oceanic layer and differs in biogeochemical composition to the underlying subsurface water (SSW), it is important to determine whether processes in the SML modulate gas exchange, particularly for climate active gases. Enrichment of dimethyl sulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) has been reported in the SML, but it remains unclear how this is maintained whilst DMS is lost to the atmosphere. To examine this, a comprehensive study of DMS source and sink processes, including production, consumption, and net response to irradiance, was carried out in deck-board incubations of SML water at five locations in different water masses in the southwestern Pacific east of New Zealand. Net consumption of DMSP and production of DMS in the light and dark occurred at all sites. The net response of DMS and DMSP to irradiance varied between stations but was always lower than conversion of DMSP to DMS in the dark. In addition, DMS photolytic turnover was slower than reported elsewhere, which was unexpected given the high light exposure in the SML incubations. Although no relationships were apparent between DMS process rates and biogeochemical variables, including chlorophyll <span class="inline-formula"><i>a</i></span>, bacteria, and phytoplankton groups, net bacterial DMSP consumption was correlated with DMSP and DMS concentrations and also dinoflagellate and <i>Gymnodinium</i> spp. biomass, supporting the findings of a companion study that dinoflagellates play an important role in DMS cycling in the SML. However, net DMS production rates and accumulation were low relative to regional air–sea DMS loss, indicating that DMS cycling within the SML is unlikely to influence regional DMS emissions.</p>https://os.copernicus.org/articles/18/1559/2022/os-18-1559-2022.pdf |
| spellingShingle | A. D. Saint-Macary A. D. Saint-Macary A. Marriner S. Deppeler K. A. Safi C. S. Law C. S. Law Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates Ocean Science |
| title | Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates |
| title_full | Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates |
| title_fullStr | Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates |
| title_full_unstemmed | Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates |
| title_short | Dimethyl sulfide cycling in the sea surface microlayer in the southwestern Pacific – Part 2: Processes and rates |
| title_sort | dimethyl sulfide cycling in the sea surface microlayer in the southwestern pacific part 2 processes and rates |
| url | https://os.copernicus.org/articles/18/1559/2022/os-18-1559-2022.pdf |
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