Seasonal DOC accumulation in the Black Sea: a regional explanation for a general mechanism |
| |
| Authors: | Gustave Cauwet Gaëlle Dliat Anton Krastev Galina Shtereva Sylvie Becquevort Christiane Lancelot Andr Momzikoff Alain Saliot Adriana Cociasu Lucia Popa |
| |
| Institution: | Gustave Cauwet, Gaëlle Déliat, Anton Krastev, Galina Shtereva, Sylvie Becquevort, Christiane Lancelot, André Momzikoff, Alain Saliot, Adriana Cociasu,Lucia Popa |
| |
| Abstract: | During three cruises in the Black Sea, organised in July 1995 and April–May 1997, biological and chemical parameters that can influence the carbon budget were measured in the water column on the NW shelf, particularly in the mixing zone with Danube River waters. We observed in early spring (end of April–May) conditions an important input of freshwater organisms that enhanced the microbial activity in the low salinity range. High bacterial activity regenerates nitrogen in the form of nitrates, but is also responsible for an important consumption of ammonium and phosphate, leading to a high N/P ratio and a strong deficit in phosphorus. The consequence is a limitation of phytoplankton development but also a production of carbohydrates that accumulate all along the salinity gradient. These mechanisms are responsible for a seasonal accumulation of dissolved organic carbon (DOC) that increases from 210 μM in winter to about 280 μM in summer. All this excess DOC disappears during winter, probably degraded by bacterial activity. The degradation of carbon-rich organic matter increases the phosphorus demand by bacteria bringing limitation to phytoplankton primary production. |
| |
| Keywords: | Dissolved organic carbon Carbon cycling Accumulation Productivity Microbial loop Nutrients consumption Carbohydrates Black Sea Danube Mixing zone |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
