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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2018-411
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2018-411
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 11 Oct 2018

Research article | 11 Oct 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Patterns and drivers of dimethylsulfide concentration in the northeast Subarctic Pacific across multiple spatial and temporal scales

Alysia E. Herr1, Ronald P. Kiene2, John W. H. Dacey3, and Philippe D. Tortell1,4,5 Alysia E. Herr et al.
  • 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
  • 2Department of Marine Sciences, University of South Alabama, Mobile, AL, 36688, USA
  • 3Woods Hole Oceanographic Institute, Woods Hole, MA, 02543, USA
  • 4Botany Department, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
  • 5Peter Wall Institute for Advanced Studies, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada

Abstract. The northeast subarctic Pacific (NESAP) is a globally important source of the climate-active gas dimethylsulfide (DMS), yet the processes driving DMS variability across this region are poorly understood. Here we examine the spatial distribution of DMS at various spatial scales across contrasting oceanographic regimes of the NESAP. We present a new data set of high spatial resolution DMS measurements across hydrographic frontal zones along the British Columbia continental shelf, together with key environmental variables and biological rate measurements. We combine these new data with existing observations to produce a revised summertime DMS climatology for the NESAP, yielding a broader context for our sub-mesoscale process studies. Our results demonstrate sharp DMS concentration gradients across hydrographic frontal zones, and suggest the presence of two distinct DMS cycling regimes corresponding to microphytoplankton-dominated waters along the continental shelf, and nanoplankton-dominated cross-shelf transitional waters. DMS concentrations across the continental shelf transition (range <1–10nM, mean 3.9nM) exhibited positive correlations to salinity (r=0.80), sea surface height anomaly (SSHA; r=0.51) and relative prymnesiophyte abundance (r=0.88). In contrast, DMS concentrations in near shore coastal transects (range <1–24nM, mean 6.1nM) showed a negative correlation with salinity (r=−0.69, r=−0.78) and SSHA (r=−0.81, r=−0.75), and a positive correlation to relative diatom abundance (r=0.88, r=0.86). These results highlight the importance of bloom-driven DMS production in continental shelf waters of this region, and the role of prymnesiophytes in DMS cycling further offshore. In all areas, the rate of DMS consumption appeared to be an important control on observed concentration gradients, with higher DMS consumption rate constants associated with lower DMS concentrations. A compiled dataset of all available summertime DMS observations for the NESAP (including previously unpublished results) was used to examine the performance of several existing algorithms to predict regional DMS concentrations. We found that none of these existing algorithms was able to accurately reproduce observed DMS distributions across the NESAP, although performance was improved by the use of regionally tuned-coefficients. Based on our compiled observations, we derived an average summertime distribution map for DMS concentrations and sea–air fluxes across the NESAP. We estimated that this region emits 0.30Tg of sulfur to the atmosphere during the summer season.

Alysia E. Herr et al.
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Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Alysia E. Herr et al.
Alysia E. Herr et al.
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Short summary
Dimethylsulfide (DMS) is an essential component of the global sulfur cycle and a major source of climate-influencing aerosols. We examine the drivers of DMS concentration gradients along the British Columbia shelf by comparing DMS measurements to environmental variables and biological rates. We further combine new and existing data sets to provide a new summertime DMS climatology for the northeast Subarctic Pacific. Our results highlight the importance of phytoplankton taxonomy to DMS cycling.
Dimethylsulfide (DMS) is an essential component of the global sulfur cycle and a major source of...
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