Earth & Space
Why is seawater salty?
They follow salt with a picture card instead of their tongues.
The short answer
Water dissolves material from rocks, and rivers carry dissolved salts to the sea. When seawater evaporates, most salt stays behind. Inputs and other processes work over very long times. Rivers do not simply carry visible salt grains.
An imagined Wusel scene
Puschel and Flauschi investigate
A closed seawater container and a little bowl of table salt stand on the teaching table. Puschel“Has somebody seasoned the sea like soup?”
Flauschi puts a river picture beside them. Flauschi“Water dissolves materials from rocks. Rivers carry dissolved salts to the sea.”
Puschel cannot see salt grains in the container. Puschel“So salts can be in water even when they are not lying around.”
Flauschi“Exactly. And when water evaporates, salt does not simply fly away with it.”
Puschel leaves the container closed. Puschel“My tongue does not need to be a sea scientist today.” They follow the river to the coast on the card.
Little Wusel quiz
Do rivers contain dissolved salts at all?
Choose one answer: a), b).
- a)Yes, usually much less than seawater.
- b)No, river water never contains any.
Show answer
Correct answer: a): Yes, usually much less than seawater. Yes. Rivers contain dissolved salts, usually in smaller amounts.
What happens to salt when water evaporates?
Choose one answer: a), b).
- a)It travels away with the water vapour.
- b)It stays behind.
Show answer
Correct answer: b): It stays behind. The salt stays behind.
Word help
- evaporation
- Liquid becomes gas at its surface, even without boiling.
Explore in more detail
Here you will find longer explanations and further details. You can explore them together.
Understand step by step
How it works – simply explained
Water carries substances
Rain and flowing water dissolve rock ingredients. Rivers carry them onward even without visible salt grains.
Substances enter the ocean
Over time salts arrive from rivers and seafloor processes. Seawater contains different salts.
Evaporation leaves salt
Water enters air as vapour while dissolved salts mostly remain. This contributes to salinity. Rivers contain dissolved substances too, usually in lower amounts.
The key points again
Discovery 1
Rain and flowing water dissolve tiny materials from rocks. Rivers carry dissolved salts to the sea. Dissolved means spread through the water without remaining as visible grains.
Source: [1]
Discovery 2
Materials also enter water at the seafloor. Seawater contains different salts, not just kitchen salt.
Source: [1]
Discovery 3
When seawater evaporates, salt stays behind. Rivers also contain dissolved materials, but usually much less salt than seawater.