Like so many other things, one of the universal truths that we have all verified is that river water is sweet, and that sea water is salty. Surely as a child you have wondered why this is so, and why it is called "sweet water" when it really does not taste sweet, but is tasteless. It is likely that you have a slight idea of the answer to these questions, or you may not or you do not know how to explain it to someone who does not know. If this is the case, find out why the water of the rivers is sweet in this Green Ecologist article.
Where is fresh water found
Fresh water refers to the water that is found naturally on the earth's surface. Only 3% of the planet's water is fresh and it is found in different ways, such as:
- Layers of ice.
- Glaciers
- Icebergs.
- Lakes.
- Lagoons
- Wetlands
- Rivers.
- Streams.
- Underground, in aquifers.
East term for "sweet" began to be used to mark a clear opposition to the term "salt water" of seas and oceans. The truth is that fresh water is not sweet as such, but is colorless and tasteless, and is characterized by having a very low concentration of dissolved salts in it, although we do not notice it on our palate. This means that fresh water also contains mineral salts such as calcium, silica, magnesium or iron, but not at the level of salt water.
The water cycle
The first step in trying to explain why the water in rivers, lakes, wetlands, etc., is sweet, is to understand the source of the water in these rivers and the entire process that follows, that is, to analyze the cycle of the Water.
It is true that the source of practically all fresh water is precipitation, which can manifest itself in the form of rain, snow, or fog. In addition, the accumulated water in the form of ice and snow also produces a contribution of fresh water with the thaw.
With the rainfall comes fresh water to the earth's surface. These precipitations already contain materials that were dissolved in the atmosphere from which they come, as well as from the sea or the land on which the clouds have moved until the moment of the "discharge" of water.
This water that reaches the earth's surface seeps underground or slip on the ground if it is sloping, as can occur on mountain slopes. In this way it originates or feeds rivers that finally flow into the sea. Here, the water evaporates again and it starts the cycle again with the formation of new clouds.
If at this point you have not yet come up with an idea, we will provide you with a key piece of information. Numerous mineral substances and salts are found on the earth's surface. This may give you some clue. With the water that falls through the precipitations the erosion of the terrestrial surface takes place, reason why these substances are dragged until the rivers and along the route of these until their mouths in seas.
From here we can conclude a first point, and that is that the salinity of seas and oceans comes from entrained and transported substances during the water cycle. Although it is not the only reason.
But this first conclusion can also open another new doubt. Many rivers, before reaching the sea, flow into lakes and lagoons that do not have the salinity of these marine environments. So what's going on? What piece of the puzzle are we missing?
Why sea water is salty and river water is not
Well, as we previously concluded, one of the reasons why the sea and oceans are salty is due to the different mineral salts and substances that are dissolved in it from rivers and the water cycle, in particular natural chemical elements. like chlorine, calcium, partner, sulfur, potassium or magnesium. But as we also said, it is not the only reason.
The proportion of water in the seas and oceans is much higher than that in rivers and lakes, since most of the water on the planet is found in them. How can it be, then, that the contribution of small rivers makes such a large body of water salty? Good, the seas and oceans, unlike rivers, they do not have water outletsIn other words, the molecules that reach them remain for thousands of years in the oceans and seas as their water is not renewed. To this is added that the greatest phenomenon that occurs in these bodies of water is evaporation due to solar rays, which, by eliminating the water, but leaving these substances increase your concentration. This is the other reason why sea water is salty, because the substances that reach it are “retained”.
Why is river water sweet or less salty?
With all the above information we should already be able to give an answer to this question.
Again, we remember that, although it is called "fresh water", the water of rivers and lakes also contains mineral salts, although in low concentrations. We also said that when these rivers flowed into the seas and accumulated these substances in them, they made them become saline as they did not have outflow streams. On the contrary, in rivers, being in continuous movement, these substances remain for a short time. Here is the key.
And in the case of the lakes? The same thing happens with them. Although the rivers flow into them mineral salts do not accumulate, since the lakes have drainage systems and water outlets. Thus, the substances it carries disappear with the water that brought them, maintaining a low concentration of salts in these lakes and lagoons.
Finally we can conclude that the water in rivers and lakes is sweet because the mineral salts and substances dissolved in the water they do not remain stagnant and retained in it, but are quickly washed up into seas and oceans.
Here below you can see a short video of a biologist professor who explains why the water of the rivers is sweet and that of the sea is salty.
If you want to read more articles similar to Why the water of the rivers is sweet, we recommend that you enter our category of Curiosities of the Earth and the universe.
