Fact sheet 3: how much salt is in the ocean?
Fact sheet 3 in our community information series. Printed copies are available from our market stall. Schools and community groups may reproduce it if the document reference is kept.
How salty is seawater?
About 3.5 per cent by weight, or 35 parts per thousand.
How much salt is in the ocean?
Around 48 quadrillion tonnes of dissolved salt, calculated from the published volume of the world's oceans and their average salinity.
Where does the salt come from?
Rain slowly breaks down rock on land, and rivers carry the dissolved minerals to the sea. Vents and underwater volcanoes add more from below. These processes are reasonably well documented and are outside the scope of our work.
Where does Kings Beach fit in?
Our focus is the part of the coastline where we live. A preliminary estimate of the salt leaving Kings Beach is being prepared for the Board. There is currently no barrier of any kind between the sand and the sea. With the ocean already holding as much salt as it does, the Board does not believe the case for adding to it has been made.
Sources: NOAA National Ocean Service; US Geological Survey.
The Kings Beach Salt Runoff Containment Proposal is a proposal to build a 6 metre concrete wall between the sand and the sea at Kings Beach, Broken Head, NSW, to stop salt reaching the ocean. It has not been approved and no works are scheduled.