CO2 - Do plants release BOTH O2 and CO2?

[Recovering Engineer]

Hi everyone. I have a few questions and would appreciate your help. I was never any good at biology in school so ... these might be stupid questions. sorry...

 

 

1) I was in the park one day and overheard a lady say "Not many people know that plants release oxygen only in the morning. By late afternoon, they release a lot of CO2". >>>>>>>>How true is this?

 

 

2) An article on TheScientist.com http://www.the-scientist.com/blog/display/57668/ mentioned that savannnas release a lot of carbon in to the atmosphere, and therefore, they are important. My question is,

 

a. How do savannas release a lot of carbon - is this what the lady in the park meant?

 

b. Now that everyone is anxious to reduce their "carbon footprint" how is it a good thing that savannas release a lot of carbon?

 

c. Can this carbon actually be captured and harnessed for fuel?

 

Here's the sentence:

 

"Furthermore, "[savannas] are able to store and release a tremendous amount of carbon, and [thus] can be reservoirs for quite a bit of the CO₂ that's in the atmosphere," he said "If we were to lose them, the ability to store carbon in this landmass goes away."

 

Thankyou for bearing with me.

 

 

[Dan6541]

Plants use photosynthesis to release oxygen only when there is light, but they release carbon dioxide all the time as a result of respiration. In the day time they release a lot more oxygen than carbon dioxide though.

 

I have no idea about question 2 though.

Edited September 3, 2010 by Dan6541

[Moontanman]

Here's the sentence:

 

"Furthermore, "[savannas] are able to store and release a tremendous amount of carbon, and [thus] can be reservoirs for quite a bit of the CO₂ that's in the atmosphere," he said "If we were to lose them, the ability to store carbon in this landmass goes away."

 

Thankyou for bearing with me.

 

 

Savannas are covered by grass and grass grows fast and absorbs carbon fast as well. This carbon can be released by grazing animals or released even faster by fire

[Recovering Engineer]

Thank you! I think your replies combined, answer my question. Rereading the quote "and [thus] can be reservoirs for quite a bit of the CO₂ that's in the atmosphere," I guess the guy meant, reservoirs contained inside the grass, not in the atmosphere itself. That was the part that confused me.

 

A new question though - regarding plants releasing CO2 all the time - does this mean esp at night and that , for instance, people who keep plants in their room should try to stay away from them at night cos they are slightly poisonous then?

 

Thanks again for your help!

 

cheers

[Mr Skeptic]

Actually, increasing the amount of CO2 will help you sleep. Unless you have trouble breathing, a little extra CO2 won't hurt you. People release much more CO2 than any houseplant anyways.

[Greenfaerie]

A hefty amount of CO2 is released when plants (especially trees) die and rot away.

[pioneer]

Shellfish can turn CO2 into an inorganic state (the shell) that is more permanent, compared to the organic fixation of CO2 by plants. A plant will fix CO2, but when it dies most of the CO2, within the wood or plant material, will be returned to the earth. for recycle. A shell is longer term storage.

Edited September 3, 2010 by pioneer

[skyhook]

The gnu eat the grass and they produce poop. There is methane in cow dung, which can be broken down into CO2. so maybe the other animals of the Savannah is the same. There can be some acacia trees in the savannah. I guess as human population expand, the savannah is going to use for residence, and sometimes it turns into desert-like if overgrazed, or due to drought.

 

c. cow dung is used by some communities as fuel, for cooking. The wood from trees can be used as fire wood. Sometimes, it is possible to grow crops meant for biodiesel, and when you harvest the crops, you can utilise the carbon. It can be detrimental to the savannah system though, as grassland is converted to farmland.The animals lived in reduced natural land. The farmers might want to eliminate certain animals and birds too as they may feed on the crops.

[Recovering Engineer]

How exactly does CO2 help you sleep? Is it the same principle as CO poisoning making you sleep ...to death?

 

1) Do plants release pretty much the same amount of CO2 day or night (respiration on same level all day long?)

 

OR

 

2) Do they respire more during photosynthesis,

thus releasing more CO2 in the day (although this is compensated by a lot of O2 release)

and releasing less CO2 in the night (with no O2 release to compensate the CO2)

[Recovering Engineer]

I think I'm realizing from all this that it is healthier to go jogging in the morning (more O2) than in the evening....

[Mr Skeptic]

I think I'm realizing from all this that it is healthier to go jogging in the morning (more O2) than in the evening....

 

I do hope you realize that oxygen is extremely toxic.

[dttom]

I think an increase in blood CO2 makes one more alert, mediated by chemosensitive cells in nervous system.

[Maximus Semprus Veridius]

I have several different solutions to why that plants release CO2 when they die. (Btw these are essentially GUESSES, so please correct if I am wrong, although I don't have to tell you that!!)

 

1) Because the lifeforms that are perpetuated because of the fallen tree respire and release CO2.

 

or

 

2) Something (i'm not sure), to do with the Nitrogen cycle.

[dttom]

Possibly the denitrification releases CO2, but as the plant die, if it is decomposed, majority of the carbon will be oxidized to CO2.

[CharonY]

Denitrification does not produce CO2 per se, but the oxidation of an organic electron donor might (as with any other form of aerobic or anaerobic respiration).

As mentioned, the release of CO2 is the result of microbial decomposition of the organic plant material.