The Ural River, also in the north, and the Kura River in the west, are also significant tributaries. The inflowing fresh water from these rivers dilute the water. Salinity changes from north to south, from 1.0 to 13.5 parts per thousand (ppt), according to Casp Info, a data-management project about the Caspian Sea funded by the European Union. By contrast, the North Atlantic Ocean has a salinity of 37 ppt, according to Encyclopedia Britannica.