Temporal dynamics of dissolved combined neutral sugars and the quality of dissolved organic matter in the Northwestern Sargasso Sea

Stuart J. Goldberg, Craig A. Carlson, Dennis A Hansell, Norm B. Nelson, David A. Siegel

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

The dynamics of dissolved combined neutral sugars (DCNS) were assessed in the upper 250m at the Bermuda Atlantic Time-series Study (BATS) site between 2001 and 2004. Our results reveal a regular annual pattern of DCNS accumulation with concentrations increasing at a rate of 0.009-0.012μmolCL -1d -1 in the surface 40m from March to July and reaching maximum mean concentrations of 2.2-3.3μmolCL -1. Winter convective mixing (between January and March) annually exported surface-accumulated DCNS to the upper mesopelagic zone (100-250m), as concentrations increased there by 0.3-0.6μmolCL -1. The exported DCNS was subsequently removed over a period of weeks following restratification of the water column. Vertical and temporal trends in DCNS yield (% of DOC) supported its use as a diagenetic indicator of DOM quality. Higher DCNS yields in surface waters suggested a portion of the DOM accumulated relatively recently compared to the more recalcitrant material of the upper mesopelagic that had comparably lower yields. DCNS yields and mol% neutral sugar content, together, indicated differences in the diagenetic state of the surface-accumulated and deep pools of DOM. Seasonally accumulated, recently produced DOM with higher DCNS yields was characterized by elevated mol% of galactose and mannose+xylose levels. Conversely, more recalcitrant DOM from depths >100m had lower DCNS yields but higher mol% of glucose. Lower DCNS yields and elevated mol% glucose were also observed in the surface waters during winter convective mixing, indicating an entrainment of a diagenetically altered DOM pool into the upper 100m. A multivariate statistical analysis confirms the use of DCNS as an index of shifts in DOM quality at this site.

Original languageEnglish (US)
Pages (from-to)672-685
Number of pages14
JournalDeep-Sea Research Part I: Oceanographic Research Papers
Volume56
Issue number5
DOIs
StatePublished - May 2009

    Fingerprint

Keywords

  • Bermuda Atlantic Time-series Study (BATS) site
  • Bioavailability
  • Dissolved combined neutral sugars (DCNS)
  • Dissolved organic matter (DOM)

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography

Cite this