Preprints
https://doi.org/10.5194/bg-2021-174
https://doi.org/10.5194/bg-2021-174

  06 Jul 2021

06 Jul 2021

Review status: a revised version of this preprint is currently under review for the journal BG.

Dimethylated sulfur compounds in the Peruvian upwelling system

Yanan Zhao1, Dennis Booge1, Christa A. Marandino1, Cathleen Schlundt1, Astrid Bracher2,3, Elliot L. Atlas4, Jonathan Williams5,6, and Hermann W. Bange1 Yanan Zhao et al.
  • 1GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 2Phytooptics Group, Physical Oceanography of Polar Seas, Climate Sciences, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 3Department of Physics and Electrical Engineering, Institute of Environmental Physics, University of Bremen, Bremen, Germany
  • 4Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
  • 5Atmospheric Chemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany
  • 6Energy, Environment and Water Research Centre, The Cyprus Institute, 1645 Nicosia, Cyprus

Abstract. Our understanding of the biogeochemical cycling of the climate-relevant trace gas dimethylsulfide (DMS) in the Peruvian upwelling system is still limited. Here we present, oceanic and atmospheric DMS measurements which were made during two shipborne cruises in December 2012 (M91) and October 2015 (SO243) in the Peruvian upwelling region. Dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) were also measured during M91. Relatively low DMS concentrations were measured in surface waters in October 2015 (1.9 ± 0.9 nmol L−1) and December 2012 (2.5 ± 1.9 nmol L−1). Nutrient availability appeared to be the main driver of the observed variability in the surface DMS distributions in the coastal areas. DMS, DMSP and DMSO showed maxima in the surface layer and no elevated concentrations associated with the oxygen minimum zone off Peru were measured. The possible role of DMS, DMSP and DMSO as radical scavengers (stimulated by nitrogen limitation) is supported by their negative correlations with N : P (sum of nitrate and nitrite: dissolved phosphate) ratios. Large variations in atmospheric DMS mole fractions were measured during M91 (144.6 ± 95.0 ppt) and SO243 (91.4 ± 55.8 ppt); however, the atmospheric mole fractions were generally low, and the sea-to-air flux density was primarily driven by seawater DMS. The Peruvian upwelling region was identified as a source of atmospheric DMS in December 2012 and October 2015, however, in comparison to the global monthly Lana climatology (mean: 6.2–9.8 μmol m−2 d−1 in October/December) (Lana et al., 2011), the Peru upwelling was not a hotspot of DMS emissions at either time (M91: 5.9 ± 5.3 μmol m−2 d−1; SO243: 3.8 ± 2.7 μmol m−2 d−1).

Yanan Zhao et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2021-174', Byron Blomquist, 06 Oct 2021
  • RC2: 'Comment on bg-2021-174', Anonymous Referee #2, 08 Oct 2021
  • RC3: 'Comment on bg-2021-174', Anonymous Referee #3, 20 Oct 2021

Yanan Zhao et al.

Yanan Zhao et al.

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Short summary
We present here, for the first time, simultaneously measured dimethylsulfide (DMS) seawater concentrations and DMS atmospheric mole fractions from the Peruvian upwelling region during two cruises in December 2012 and October 2015. Our results indicate low oceanic DMS concentrations and atmospheric DMS molar fractions in surface waters and the atmosphere, respectively. In addition, the Peruvian upwelling region was identified as an insignificant source of DMS emissions during both periods.
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