Source of ocean salinity?

Source of ocean salinity?

• A. Sea evaporation
• B. Weathering of rocks and rivers
• C. Photosynthesis
• D. Volcanic outgassing

Answer: (B)

Salinity in the oceans mainly comes from dissolved minerals that are weathered out of rocks on land and carried to the sea by rivers. Over long timescales, chemical weathering releases ions such as sodium and chloride into runoff, and rivers transport these dissolved salts into the oceans. In the sea, evaporation can remove fresh water and leave the salts behind, increasing salinity, but the actual source of the dissolved salts is land weathering and river input. Photosynthesis uses nutrients and does not contribute to salinity, and volcanic outgassing releases gases rather than dissolved salt ions, so it doesn’t establish ocean salinity.

Salinity in the oceans mainly comes from dissolved minerals that are weathered out of rocks on land and carried to the sea by rivers. Over long timescales, chemical weathering releases ions such as sodium and chloride into runoff, and rivers transport these dissolved salts into the oceans. In the sea, evaporation can remove fresh water and leave the salts behind, increasing salinity, but the actual source of the dissolved salts is land weathering and river input. Photosynthesis uses nutrients and does not contribute to salinity, and volcanic outgassing releases gases rather than dissolved salt ions, so it doesn’t establish ocean salinity.