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 language | English (US) |
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Pages (from-to) | 672-685 |
Number of pages | 14 |
Journal | Deep-Sea Research Part I: Oceanographic Research Papers |
Volume | 56 |
Issue number | 5 |
DOIs | |
State | Published - May 1 2009 |
Keywords
- Bermuda Atlantic Time-series Study (BATS) site
- Bioavailability
- Dissolved combined neutral sugars (DCNS)
- Dissolved organic matter (DOM)
ASJC Scopus subject areas
- Oceanography
- Aquatic Science