Water mass mixing: The dominant control on the zinc distribution in the North Atlantic Ocean

Saeed Roshan, Jingfeng Wu

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Dissolved zinc (dZn) concentration was determined in the North Atlantic during the U.S. GEOTRACES 2010 and 2011 cruise (GOETRACES GA03). A relatively poor linear correlation (R<sup>2</sup>0.756) was observed between dZn and silicic acid (Si), the slope of which was 0.0577nM/μmol/kg. We attribute the relatively poor dZn-Si correlation to the following processes: (a) differential regeneration of zinc relative to silicic acid, (b) mixing of multiple water masses that have different Zn/Si, and (c) zinc sources such as sedimentary or hydrothermal. To quantitatively distinguish these possibilities, we use the results of Optimum Multi-Parameter Water Mass Analysis by Jenkins et al. (2015) to model the zinc distribution below 500m. We hypothesized two scenarios: conservative mixing and regenerative mixing. The first scenario (conservative) could be modeled to results in a correlation with observations with a R<sup>2</sup>0.846. In the second scenario, we took a Si-related regeneration into account, which could model the observations with a R<sup>2</sup>0.867. Through this regenerative mixing scenario, we estimated a Zn/Si0.0548nM/μmol/kg that may be more realistic than linear regression slope due to accounting for process b. However, this did not improve the model substantially (R<sup>2</sup>0.867 versus0.846), which may indicate the insignificant effect of remineralization on the zinc distribution in this region. The relative weakness in the model-observation correlation (R<sup>2</sup>~0.85 for both scenarios) implies that processes (a) and (c) may be plausible. Furthermore, dZn in the upper 500m exhibited a very poor correlation with apparent oxygen utilization, suggesting a minimal role for the organic matter-associated remineralization process. Key Points Dissolved zinc shows a relatively weak correlation with silicic acid in the North Atlantic Dissolved zinc in the North Atlantic is mainly controlled by water mass mixing Some water mass end-members exhibit deviations in the Zn-Si correlation

Original languageEnglish (US)
Pages (from-to)1060-1074
Number of pages15
JournalGlobal Biogeochemical Cycles
Volume29
Issue number7
DOIs
StatePublished - Jul 1 2015

Keywords

  • mixing
  • North Atlantic
  • silicic acid
  • zinc

ASJC Scopus subject areas

  • Global and Planetary Change
  • Atmospheric Science
  • Environmental Science(all)
  • Environmental Chemistry

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