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Name: Annemarie M.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 7/23/2004
Question:
What is the normal differences between oxygen levels in saltwater and freshwater?

Replies:
Annemarie,

In a normal freshwater stream, one wants to ideally have a dissolved oxygen (DO) concentration of at least 6 ppm or greater. One does not want to have less than 4 ppm DO in the water because at this concentration range, fish can normally not survive.

Oxygen is more easily dissolved into water with low levels of dissolved or suspended solids. Waters with high amounts of salt, such as the ocean (which contains about 35 grams of salt for each 1000 grams of water) have low concentrations of DO. As the amount of salt in any body of water increases, the amount of dissolved oxygen decreases. An increase in salt concentration due to evaporation of water from an ecosystem tends to reduce the dissolved oxygen available to the ecosystems inhabitants. I hope that this helps.

Sincerely,

Bob Trach


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