Back to Search
Start Over
Large, non-Redfieldian drawdown of nutrients and carbon in the extratropical North Atlantic Ocean (46°N): Evidence for dinitrogen fixation.
- Source :
- Limnology & Oceanography; Sep2008, Vol. 53 Issue 5, p1-1, 1p
- Publication Year :
- 2008
-
Abstract
- Considerable drawdown of total dissolved inorganic carbon (C<subscript>T</subscript>) and oversaturation of oxygen (O<subscript>2</subscript>) within a cold (15°C) oligotrophic eddy in the extratropical North Atlantic Ocean (46°N, 20.5°W) indicate that, despite the absence of nitrate (NO<subscript>3</subscript><superscript>-</superscript>), the eddy was highly productive. Estimates of net community production using the mass balances of C<subscript>T</subscript> and O<subscript>2</subscript> were two to five times greater than those obtained using the mass balance of NO<subscript>3</subscript><superscript>-</superscript>. The remineralization rates obtained using the integrated rates of C<subscript>T</subscript> and NO<subscript>3</subscript><superscript>-</superscript> accumulation and O<subscript>2</subscript> utilization for the upper thermocline waters (35-300-m depth) were in agreement with C<subscript>T</subscript>- and O<subscript>2</subscript>-based net community production over the same period; however, all the estimates exceeded the NO<subscript>3</subscript><superscript>-</superscript>-based net community production by a factor of two to five, pointing to a considerable accumulation of NO<subscript>3</subscript><superscript>-</superscript> in the upper thermocline in excess of changes in the mixed-layer NO<subscript>3</subscript><superscript>-</superscript> inventory. The amount of this excess NO<subscript>3</subscript><superscript>-</superscript> suggests that a considerable fraction of the net community production was not supported by the mixed-layer NO<subscript>3</subscript><superscript>-</superscript> inventory and that an external source of NO<subscript>3</subscript><superscript>-</superscript> must be present. Of the various mechanisms that might explain the inequity between NO<subscript>3</subscript><superscript>-</superscript> drawdown in the surface layer and NO<subscript>3</subscript><superscript>-</superscript> accumulation in the upper thermocline, N<subscript>2</subscript> fixation is the most viable yet surprising mechanism for producing such excess NO<subscript>3</subscript><superscript>-</superscript> in this oligotrophic eddy. A significant fraction of net community production in oligotrophic extratropical waters could be supported by processes that are not fully explored or to date have been considered to be insignificant. [ABSTRACT FROM AUTHOR]
- Subjects :
- CARBON
NITROGEN fixation
LIGHT elements
OXYGEN
INORGANIC compounds
Subjects
Details
- Language :
- English
- ISSN :
- 00243590
- Volume :
- 53
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- Limnology & Oceanography
- Publication Type :
- Academic Journal
- Accession number :
- 34945275
- Full Text :
- https://doi.org/10.4319/lo.2008.53.5.1697