UPSC CAPF AC 2016 Paper

Ocean water salinity do changes by process of evaporation and precipitation In evaporation, water from oceans are converted into vapours leaving the salt in the ocean, so salinity of ocean increases. During precipitation, fresh rain water is added into. the ocean/sea, so it will causes dilution of ocean water and will reduce the salinity. Temperature brings about change in the ocean water's salinity. As water becomes cool, its density increases, maximum density of water is at 4°C. Beyond the 4°C gradually forming of ice starts to take place and density of it also decreases. However, freshwater freezes at 0°C. When ice formation starts to take place, salt are excluded from the ice, a process known as brine rejection and water surrounding the ice become much denser.
Many terrestrial rivers finally drain into the sea. These rivers bring dissolved salt from the rocks of land by process of weathering and erosion. River finally deposit them in ocean and sea and in this way, they changes the salinity of ocean or sea.