Categorization of water in the environment

The categorization of water in the environment is discussed in detail in Section 3.5. Here, it is sufficient to use the simple and convenient categorization of natural waters  

For the sake of completness we should mention brackish waters which are somewhere between terrestrial waters and seas. They are semi-closed water areas , freely connected with open sea, in which sea water is mixed with fresh water coming from the land. Therefore, their salinity varies quite remarkably. From the ecological viewpoint they should be considered as an independent type of water with its own particular character of biological habitat [28]. 

---