The most basic answer to how sea water and fresh water differ is salt. Seawater has a high saline content. This allows for a different ecosystem than fresh water. It also allows for different properties of the water itself. For example, salt water requires much colder temperatures to freeze than fresh water. Ice does form in the sea, but not as easily as it forms in fresh water like lakes. Another such difference in properties is that seawater is much denser than fresh water. The salt allows for higher surface tension as well. Consider the Red Sea, which has one of the higher salt contents on the planet. It is possible for a person the float completely flat along the surface of the water because the increased salt content creates a high density and surface tension. Animals living in seawater cannot usually survive in fresh water. Both types of water have distinct ecosystems. Freshwater is naturally occuring just like seawater, but it occurs in different areas. Freshwater is often found in rivers and lakes as well as springs. Many sources of freshwater eventually run into the sea and become seawater.
Posted by wannam
on February 21, 2012 at 4:07 AM (Answer #1)