WHY IS THE SEA SALTY?

Many parents live in dread of being asked a question by their child and not knowing the answer. Take this example ‘…why is sea water salty…? it seems simple enough but get the answer wrong and you could be on the road to having your child lose faith in your role as an – up ‘til now – all knowing figurehead.

However, all is not lost because the answer to why the sea is salty is simple enough.

The saltiness in our oceans is the result of millions of years of minerals leaching and dissolving from the stones and rocks found within the earth. While the largest proportion of dissolved salts comes from our rivers, a good quantity of these salts are dissolved from rocks and sediments below the ocean floor, and released through volcanic vents. To a lesser degree the weather is also a contributing factor as rain also deposits mineral particles into the oceans.

As time goes on the sun's heat distils or evaporates almost pure water from the surface of the sea, and this leaves the salts and minerals behind. The water returns to the ocean, via rivers or rain washing down even more salt which becomes ever more concentrated. This process is part of the continual exchange of water between the Earth and the atmosphere that is called the hydrological or water cycle.

At this moment in time our seas have an average salinity of approximately 3.5% sodium chloride. This equates to an incredible 50 million billion tonnes of salt in solution within our oceans. Interestingly salinity isn't the same across the globe. Water nearer the poles becomes less salty as it is diluted by melting ice. Conversely, the higher temperatures in the tropics causes greater levels of evaporation makes water there both saltier and denser,

For related articles click onto the following links:
WHERE DOES THE WIND COME FROM?
WHY IS THE SEA SALTY?