# Will dissolved oxygen increase in a water sample inside a jar?

• Frankenstein19
In summary, when the cap is removed from a glass containing 100mL of water and the temperature is decreased by 20 degrees without agitation, the amount of dissolved oxygen remains the same but the percentage oxygen saturation increases. However, there is a possibility that some excess gas may leave the solution and enter the atmosphere in the glass, which could reduce the absolute amount of dissolved oxygen.
Frankenstein19
TL;DR Summary
I know dissolved oxygen increases in water as temperature decreases.

But if I pour some water in a jar and close it, and then decrease temperature, will the DO increase if the sample is just laying in the jar? (No agitation)
If I have 100mL inside a glass with a closed cap. I take the cap off, measure DO, put the cap back on and decrease the temperature 20 degrees. No agitation of any sort.

Does the DO increase?

The amount of oxygen dissolved in the water remains the same.
However, the percentage oxygen saturation in the water will increase.
10% oxygen saturation is the max amount of oxygen the water can maintain in solution under the conditions.

100% oxygen saturation will be less at higher temperatures, but the absolute amount of oxygen will will not. Therefore the percentage oxygen saturation will go up in the sample.

However, it possible that some excess gas will leave solution and go into the atmosphere in the enclose atmosphere of the glass, if any (especially if its about 100% saturation). This will reduce the absolute amount of dissolved oxygen in the water and increase the pressure of the atmosphere in the glass (if its sealed). This is like CO2 in a sealed a bottle of soda.

pinball1970

## 1. How does dissolved oxygen affect water quality?

Dissolved oxygen is a measure of the amount of oxygen gas that is dissolved in water. It is an important indicator of water quality because it is essential for the survival of aquatic organisms.

## 2. What factors can cause an increase in dissolved oxygen in a water sample?

There are several factors that can contribute to an increase in dissolved oxygen in a water sample, including photosynthesis by aquatic plants, aeration from wind or waves, and diffusion from the atmosphere.

## 3. Will the dissolved oxygen level in a water sample increase if it is stored in a jar?

Yes, the dissolved oxygen level in a water sample may increase if it is stored in a jar. This is because the water will be in a closed environment, limiting the exchange of gases with the atmosphere and allowing for the accumulation of oxygen produced by photosynthesis or other sources.

## 4. How long should a water sample be stored in a jar to see an increase in dissolved oxygen?

The amount of time it takes for the dissolved oxygen level to increase in a water sample stored in a jar will depend on various factors such as the initial dissolved oxygen level, the temperature, and the amount of light available for photosynthesis. It is recommended to monitor the sample for at least 24 hours to see a noticeable increase.

## 5. Can the dissolved oxygen level in a water sample inside a jar continue to increase indefinitely?

No, the dissolved oxygen level in a water sample inside a jar will eventually reach equilibrium, where the amount of oxygen being produced or diffused is equal to the amount being consumed by organisms or other processes. This equilibrium level will depend on the specific conditions of the water sample and may vary over time.

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