Changes in sea water salinity
Salinity changes occur near edges of oceans
- Where Amazon River flows into sea, find nearly fresh water 100 km off shore
- In Persian Gulf, where shallow sea water evaporates & there is little precipitation or river recharge, salinity approaches 40‰
- Freezing sea water at high latitudes causes salinity to approach 38‰
Generally, however, sea water salinity is roughly constant, & it appears to have had this value for a long time