The concentration of dissolved salts in water is measured by salinity. The electrical conductivity (EC) of the water is used to determine salinity. When compared to water with no dissolved salt, saltwater conducts greater electricity. Ocean water has a salinity of roughly 34 to 36 parts per thousand, but fresh water has essentially no dissolved salt (ppt). Fresh and saltwater mingle to form brackish water.
Because different types of animals and plant life may exist in different salinity ranges, salinity is an essential indicator of water quality. Even a little change in salinity can stress or kill these species, wreaking havoc on the local and wider ecology.Urban and rural runoff from industry, sewage, agriculture, and stormwater are all sources of salinity in freshwater. Salinity levels can be raised as a result of clearing vegetation because the water table rises. Between low and high tide, the salinity of areas inside the tidal limit of rivers that run into the sea will fluctuate. Freshwater entering the estuary from streams usually meets seawater pouring in from the ocean, resulting in a gradual change in salinity.
HOW IS SALINITY CREATED?
Primary salinity, secondary salinity, and tertiary salinity are the three types of salinity that can be created.
1- The most prevalent way is primary salinity, which is caused by natural processes such as the accumulation of salt from rainfall over time. Some of the salt in this water will evaporate from bodies of water or land when it rains. Some of the salt may also be absorbed straight into the groundwater or soil. A little portion of this water will flow into rivers and streams before eventually reaching the oceans and lakes.
2- Secondary salinity develops when groundwater levels rise, which is mainly caused by plant removal from a given location.
3- Salinity can also be created by tertiary salinity, which occurs when water is repeatedly sprayed to horticulture and crops. A little amount of water evaporates each time it is applied to the crops, resulting in an increase in salt concentration. Crops can have very high salt concentrations if water is reused on a regular basis.
IMPORTANCE OF MEASURING SALINITY
There are numerous advantages to evaluating the salinity of water. The specific rewards, however, are dependent on the industry in which you work. As previously mentioned, determining the salinity of water is critical in estuaries and oceans where freshwater and saltwater mingle. Because each aquatic organism requires a particular degree of salinity to exist, evaluating the salinity of water is required if you want to ensure that different bodies of water can support the diverse species of organisms that reside there. The aquatic creatures present in seawater may survive in water with salinity levels as high as 40 parts per trillion.
Organisms that require freshwater to survive, on the other hand, are usually unable to survive in water with a salinity of more than 1ppt. Remember that salinity affects the amount of dissolved oxygen in the water. When salt levels rise, oxygen becomes less soluble, resulting in a decrease in the amount of dissolved oxygen in the water. Dissolved oxygen is essential for the survival of many aquatic creatures. When compared to oxygen in freshwater, oxygen in seawater is around 20% less soluble.
When using a salinity meter or equivalent tool to measure the salinity of water, the appropriate salinity levels are determined by the water's intended purpose. Salinity values of 0.5ppt or less should be found in freshwater used for drinking and irrigation. Aquatic ecosystems may suffer if salinity levels are less than 1ppt but greater than 0.5ppt. The water is deemed saline with salinity levels of 2-10ppt, making it suitable for the majority of animals. The water is deemed highly saline when the salinity levels are between 10-35ppt and should only be utilized for particular types of cattle.
Brine is defined as water with a salt content greater than 35 parts per thousand, which is the type of water you'll find in the ocean. For industrial and mining reasons, a brine solution is often utilized. For example, brine is an excellent deicing agent, which is why it's widely used to keep ice and snow from clinging to roadways throughout the winter. Other industries that use salt brine include food processing, food preservation, and industrial refrigeration. It is important to determine water salinity to keep DO levels in check.