If the salinity of ocean water at the entrance to an estuary is 30‰ and the average salinity of the estuary is 20‰ what fraction of the volume of water in the estuary is fresh water?

Question

Quizplus · Accepted Answer

To solve this problem, we use the concept of the total amount of salt remaining constant. Let V1 be the volume of ocean water entering the estuary and V2 be the volume of fresh water in the estuary. Then we have:

V1 x 30‰ = V2 x 0‰ + (V1 + V2) x 20‰
Simplifying this equation gives:

3V1 = 2V2
Thus, the fraction of the volume of water in the estuary that is fresh water is:

V2 / (V1 + V2) = 2/ (2+3) = 2/5
This fraction can be simplified to 1/5 ÷ 1/2 = 1/5 x 2/1= 2/5. So, the answer is B) 1/3.

If the Salinity of Ocean Water at the Entrance to an Estuary