DOES SALT CONCENTRATION OR SALINITY OF WATER AFFECT SOLUBILITY OF OXYGEN? - PAGE 2

Salinity is important in coastal waterways for the following reasons:

• Salinity is a dynamic indicator of the nature of the exchange system.
• The salinity of the water within the estuary tells us how much fresh water has mixed with sea water.
• Plots that show the relationship between salinity and other soluble substances (e.g. nutrients) can be used to demonstrate the dynamic or conservative nature of those substances in 'mixing plots';
• Salinity is an important determinant of the mixing regime - because of the density variation associated with salinity variation, salinity stratification tends to inhibit vertical mixing in an estuary; which can have important implications for dissolved oxygen concentrations.

So it can be said that oxygen solubility decreases slightly as salinity increases, but oxygen solubility decreases more as temperature goes up regardless of salinity. There is however, a sizable difference in oxygen solubility in freshwater and seawater. Solubility of oxygen in seawater is 21% less than that of freshwater at 32 degrees Fahrenheit and 17 % less than that of freshwater at 100 degrees Fahrenheit. Oxygen solubility in freshwater decreases from 14.6 to 8.24 mg/L as temperature rises from 32 to 100 degrees. This is a 46.3% decrease. On the other hand, oxygen solubility in seawater decreases from 11.5 to 6.75 mg/L for this same temperature increase, a decreased oxygen solubility of 41.3%.

The salt concentration directly affects the salinity which impacts circulation with estuaries and coastal regions can derive from or be strongly influenced by the density variation associated with salinity. In effect, dense saline water tends to flow under fresh water. Salinity is an important ecological parameter in its own right; and it is important in some chemical processes.

We are changing the environment every day by the choices we make. The salt and chemicals that are released from industries and residential water softeners do have an effect on our natural water sources. For our homes, there are better alternatives including salt-free water conditioners which can reduce scale buildup without the use of sodium. With proper knowledge, caring awareness and a positive attitude we can reduce our ecological footprint and make a big difference to the world we all share. We encourage you to learn more about how to protect our natural water resources, one drop at a time.