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Assume you are a climatologist analyzing seafloor sediment. You have a 200,000 year old cross section of sediment in which you are going to analyze the ratio of oxygen-18 to oxygen-16. During your analysis, you determine that there is a greater quantity of oxygen-18 than oxygen-16 (beyond today's present values). What does this tell you?

User Judean
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Answer:

The past climate was cooler than today.

Step-by-step explanation:

There are three naturally occurring isotopes of oxygen - O-16, O-17, and O-18, where the 16, 17 and 18 refer to the atomic mass.

The ratio of 0-16 to O-18 is used to determine the temperature using the seafloor sediments in the following manner:

1. O-18 is two neutrons heavier than O-16 and thus the water molecule in which it occurs is heavier. Due to this more energy is required to vaporize water having O-18 than water having O-16. Further water with O-18 liberates upon condensation and water with )-16 diffuses more rapidly.

2. Due to a lesser amount of energy required for the vaporization of water with O-16, the first water vapor formed during evaporation of liquid water is rich in O-16, and the residual liquid is rich in O-18.

3. As a result upon condensation of water vapor H2O-18 preferentially enters the liquid, while H2O-16 gets concentrated in the remaining vapor.

4. As an air mass moves from a warm region to a cold region, water vapor condenses followed by precipitation resulting in the removal of H2O-18, leaving behind more H2O-16 enriched water vapor causing precipitation to have lower 0-18 to O-16 ratio with a decrease in temperature.

Thus, the result of the analysis proves that the past climate was cooler than today.

User Xxddoo
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