# Do plants absorb CO2 through their roots?



## Optix (May 31, 2011)

stomata are in plant leaves
...roots transport nutrients, and water

so, nope

the NPT method uses plants that absorb the dissolved CO2 from the water...but since everything is done @low light levels, the bacteria and fish produce enough


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## HolyAngel (Oct 18, 2010)

yeah no, co2 is only taken in at the leaves where photosynthesis is taking place. They can't and will not use it anywhere else as there is nothing the plant can use it for but that.


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## mistergreen (Dec 9, 2006)

I remember reading the Diana's Walstad's book that they do.


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## extrame (May 17, 2011)

nope, i asked a chemist cousin of mine and he said that plants only absorb nutrients from the roots and absorb co2 through the leaves.. also with less water movement/agitation of water surface, there would be higher concentration of co2 in water which is why NPT tanks do necessarily need water movement.


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## Mxx (Dec 29, 2010)

Here is one thing I was able to find - 

_Aquatic plants also have requirements for certain nutrients in the overlying water. Most rooted aquatic plants need Ca, Mg, K and a carbon source in the water if they are to thrive. I say most, since some aquatic species such as Isoetes sp. and Lobelia dortmanna actually obtain even their carbon dioxide from the sediment. These plants are adapted to growing in acidic softwater lakes that have extremely low levels of DIC in the water and so absorb CO2 from the sediment through their roots. http://www.hallman.org/plant/huebert.html Dave Huebert, Department of Botany, University of Manitoba _

So Huebert says that some aquatic species are able to, although I'm not sure about our commonly kept aquatic species. 

However, many of our plants do actively inject oxygen into the substrate around their roots. This may in part be for protection, but also likely would be in order to generate their own co2. The oxygen which is readily available in the water is injected into the substrate, where bacteria utilize it to break down organics, and consequently they release co2 into the substrate in the immediate vicinity of the roots. One would reason that the plants would also be equipped to therefore absorb and utilize the co2 they are helping to produce, especially as it's such a valuable resource available in such limited quantities in many bodies of water.That's the hypothesis in any case?


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