Water salinity characteristics, Get to know more

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Purwakarta -Have you ever heard the word salinity? Well, if you come from an area far from the coast and go to a coastal area then you will find the water conditions there that feel a little different from the water conditions from your home area, the water there will taste saltier than the water away from the beach, and if you continue down to the ocean then there you will find water with a higher level of saltiness.

Salinity is the level of saltiness or levels of dissolved salts in water. Salinity can also refer to the salt content in the soil. -Wikipedia.

Most natural lakes, rivers, and waterways have a salt content so small that the water in this area is categorized as fresh water. The actual salt content of this water is, by definition, < 0.05%. If more than that, the water is categorized as brackish water or becomes saline if the concentration is 3% – 5%. And water with a salt content of >5%, it is called brine.

Rivers that flow from upstream rivers will end up downstream of the oceans, meaning that the more rivers that empty into the sea, the salinity level of seawater will decrease, because it is mixed with river water with lower levels or very low levels of salt. Meanwhile, seas that are isolated or not connected to the high seas will have high salinity.

Distribution of water salinity

Did you know that two thirds (⅔) of the Earth’s surface is covered by water. About 97% of that water is salty seawater. Only 3% of the planet Earth’s water is fresh. But 2% of the Earth’s fresh water supply is still frozen in the form of ice sheets, glaciers and soil. So that the supply of fresh water on Earth is less than (<) 1%. This fresh water plays a very big role in the process of why seawater is salty.

Citing the National Ocean Service, salt in the oceans comes from two sources, namely mineral ions runoff from land and openings in the seabed.

The sea is affected by heat currents, the salinity will rise (high). This also applies vice versa, where the sea is affected by cold currents, the salinity will decrease (low). The more evaporation occurs, the air around becomes humid. Then the higher the salinity of the sea water.

Substances that dissolve and form salts are measured in terms of salinity and are divided into 4 groups, namely:

1. Main Constituents: Cl, Na, SO4, and Mg

2. Dissolved Gases: CO2, N2, and O2

3. Nutrients: Si, N, and P

4. Trace elements: I, Fe, Mn, Pb, and Hg

Currently, NASA has succeeded in making a map of the world’s ocean salinity through special measurements that have been carried out. This map shows the salt content of the entire ocean which is distinguished by color intensity.
NASA Salinity Map

Information :

  • Red and yellow: high salt content.
  • Blue and purple: lower salt content.

The salt content of seawater is the amount of salt contained in 1,000 grams of seawater and is expressed in units per mile. The average salt content of seawater is 34.5 per mile. The following is the structure and classification of water based on salinity or salt content.

Levels of Salt Levels in Water

Brine water atau air brine (Air Asin) Chemically it is actually water that contains salt. Or chemically called H2O (water) mixed with NaCl (sodium chloride). So water that contains salt can be referred to as brine water. Brine water also varies depending on its use. In general, the variance of the salt content of brine water ranges from 3.5% NaCl content in a solution, up to the highest is about 26% NaCl content in a solution. This rate is adjusted depending on his needs.

Saline water (Air Garam) is water that contains high concentrations of dissolved salts. The concentration of salt in water is expressed as parts per million (ppm). This means that water with a dissolved salt concentration of 10,000 has a weight of 1% contributed by the salt content.

Brickish water (Air payau) ais water with a salinity level between fresh water and sea water. Salinity refers to the concentration of dissolved salts in a body of water, so brackish water is saltier than fresh water, but less salty than seawater. Brackish water has a salt concentration of 1,000 – 10,000 parts per million (PPM). In contrast, fresh water has a salt concentration of less than 1,000 PPM and seawater has a salt concentration of 30,000 – 40,000 PPM. In addition, the total dissolved solids (TDS) content of brackish water far exceeds that of drinking water. Environmental Protection Agency guidelines for drinking water are less than 500 PPM, while brackish water is between 3,000 and 10,000 PPM.

Fresh water (Air tawar) is water that does not taste the opposite of salty water. Is water that does not contain a lot of salt solution and mineral solution in it. When mentioning fresh water, people usually refer to water from a well, lake, river, snow, or ice.

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1. Goetz, P. W. (ed.): “The New Encyclopaedia Britannica (15th edn)”, Vol. 3, p.937, Encyclopaedia Britannica Inc., Chicago, 1986.

2. Lewis, E.L. (1980). The Practical Salinity Scale 1978 and its antecedents. IEEE J. Ocean. Eng., OE-5(1): 3-8.

3.. Unesco (1981a). The Practical Salinity Scale 1978 and the International Equation of State of Seawater 1980. Tech. Pap. Mar. Sci., 36: 25 pp.