| Popis: |
A simplified scheme is proposed for the carbon cycle in coastal waters, showing the main pathways and the two most important reservoirs, POC and DOC. The different steps are briefly discussed, including the sources (river inputs and primary production), the degradation steps in the water column and in the sediment, and how we can assess the capacity of the system to recycle or accumulate carbon. Several examples are presented on the different forms of carbon in estuaries and coastal zones, evidencing the specific character of rivers in different parts of the world, and the consequences in terms of carbon inputs and behaviour. The utilisation of molecular tracers is then presented as a tool to identify the origin of organic matter in coastal waters. Different examples are discussed in which one or several tracers, such as pigments, fatty acids, sterols are used to enlighten the nature and evolution of organic matter in natural environments. As a conclusion, it is shown how such regional studies, taking into account or showing the peculiarities of the studied systems, can be used to improve our knowledge on a global scale. |
