22 Jun 2022
22 Jun 2022
Status: this preprint is open for discussion.

DMS cycling in the Sea Surface Microlayer in the South West Pacific: 1. Enrichment potential determined using a novel sampler

Alexia D. Saint-Macary1,2, Andrew Marriner1, Theresa Barthelmeß3, Stacy Deppeler1, Karl Safi4, Rafael Costa Santana1,2, Mike Harvey1, and Cliff S. Law1,2 Alexia D. Saint-Macary et al.
  • 1National Institute of Water and Atmospheric Research, Wellington, 6021, New Zealand
  • 2Department of Marine Science, University of Otago, Dunedin, 9016, New Zealand
  • 3GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, 24148, Germany
  • 4National Institute of Water and Atmospheric Research, Hamilton, 3216, New Zealand

Abstract. Elevated dimethyl sulfide (DMS) concentrations in the sea surface microlayer (SML) have been previously related to DMS air-sea flux anomalies in the South West Pacific. To further address this, DMS, its precursor dimethylsulfoniopropionate (DMSP), and ancillary variables were sampled in the SML and also subsurface water at 0.5 m depth (SSW) in different water masses east of New Zealand. Despite high phytoplankton biomass at certain stations significant chlorophyll a and DMSP enrichments were only apparent at one of six stations, with the DMSP enrichment factor (EF) ranging from 0.81 to 1.25. DMS in the SML was determined using a novel gas-permeable tube technique which measured consistently higher concentrations than with the traditional glass plate technique; however, DMS enrichment was also present at only one station, with the EF ranging from 0.40 to 1.22. SML DMSP and DMS were influenced by phytoplankton community composition, with correlations with dinoflagellate and Gymnodinium biomass, respectively. DMSP and DMS concentrations were also correlated between the SML and SSW, with the difference in ratio attributable to greater DMS loss to the atmosphere from the SML. DMS in the SML did not significantly influence regional DMS emissions, with the calculated air-sea DMS flux of 1.0 to 11.0 µmol m-2 d-1 consistent with climatological estimates for the region. These results extend previous regional observations that DMS is associated with dinoflagellate abundance but indicate that additional factors are required for significant enrichment in the SML.

Alexia D. Saint-Macary et al.

Status: open (until 17 Aug 2022)

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Alexia D. Saint-Macary et al.

Alexia D. Saint-Macary et al.


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Short summary
The uppermost oceanic layer was sampled to determine what can explain a potential dimethyl sulfide (DMS) enrichment in this environment. A novel sampling method was used, and the results showed that DMS was not as enriched as expected. Our results showed that the phytoplanktonic composition influenced the DMS concentration, confirming results from another study in this oceanic region. However, additional factors are required to observe a DMS enrichment in the uppermost oceanic layer.