First basin-wide experimental results on N2-fixation in the open Mediterranean Sea.
Mediterranean Sea presents several biogeochemical anomalies compared to the global ocean. Unbalanced N budget, high nitrate/phosphate ratios in subsurface waters and light isotopic signals in particulate and dissolved nitrogen have suggested a relevant occurrence of N2-fixation. This study presents,...
| Main Authors: | , , , |
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| Format: | Conference Object |
| Language: | English |
| Published: |
Atti AIOL
2009
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| Subjects: | |
| Online Access: | http://puma.isti.cnr.it/dfdownloadnew.php?ident=cnr.ismar/cnr.ismar.ts/2009-B6-003 http://puma.isti.cnr.it/rmydownload.php?filename=cnr.ismar/cnr.ismar.ts/2009-B6-003/2009-B6-003.pdf |
| Summary: | Mediterranean Sea presents several biogeochemical anomalies compared to the global ocean. Unbalanced N budget, high nitrate/phosphate ratios in subsurface waters and light isotopic signals in particulate and dissolved nitrogen have suggested a relevant occurrence of N2-fixation. This study presents, for the first time, N2-fixation rate measurements in the open Mediterranean Sea on a basin scale during early summer, compared to one site in the North Atlantic. Very low rates (0.052?0.031 nmols N l-1d-1) were observed in all sub-regions of the Mediterranean, unlike the higher values measured in the North Atlantic surface waters (0.300?0.115 nmols N l-1d-1). No evidence of phosphate limitation emerges from this study. Low N2-fixation rates associated to light isotopic composition of PON (from -2.10 to 4.11?) suggest that other light N sources, different from atmospheric N2, fuel the Mediterranean ecosystem. |
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