Nitrogen dioxide (NO2) is a relevant air pollutant i.e. by contributing to the ozone (O3) production.

I was wondering if there are any plats or bacteria that fix NO2. I have read that legumes fix N2, but I'm unsure about NO2.

Moreover, I was wondering whether this NO2 fixation - if existing - significantly reduced local or regional NO2 concentrations improving air quality.

Can anyone answer these questions?


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    $\begingroup$ I'm voting to close this question as off-topic because it belongs in biology.stackexchange.com $\endgroup$
    – arkaia
    Commented Dec 28, 2016 at 14:41
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    $\begingroup$ I don't understand why, given that air quality questions are already in this forum. $\endgroup$
    – Diego
    Commented Dec 28, 2016 at 14:49
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    $\begingroup$ Then frame the question in terms of air quality, not just biology. $\endgroup$
    – arkaia
    Commented Dec 28, 2016 at 16:34
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    $\begingroup$ I agree with aretxabaleta that this question would be better posed in biology SE. But for what it's worth, from a thermodynamic perspective, why would any plant evolve to fix NO2? There is neither energy nor nutritional gain in doing so. $\endgroup$ Commented Dec 28, 2016 at 22:36
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    $\begingroup$ The question is on topic in the sense that it is relates to the global nitrogen cycle, greenhouse gas production and landscape sciences. It wouldn't hurt to edit the question to give a little background on the earth science aspects. $\endgroup$
    – haresfur
    Commented Dec 28, 2016 at 23:17

1 Answer 1


NO2 uptake by plants

It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations [Breuninger et al, 2013]. Currently, it is assumed that NO2 is taken up through stomata of plant leaves when the atmospheric NO2 concentrations are above a certain threshold. However, when the atmospheric NO2 concentrations are below this threshold, plant leave stomata act as sources for NO2. Therefore, this process is not fixation in the sense as N2 is fixed by legumes.

See Breuninger et al. [2013] and refernces therein for details

Canpoy reduction

Plants do not only take up (excess) NO2 actively but they decrease the concentrations of several air pollutants by providing a lot of surface for dry deposition as Christoph stated in his comment. After deposition they may revolatilize or be washed down by rain. See e.g. Grundström and Pleijel [2014] for details.

Impact on air quality

The presence of plants/trees in urban environments can reduce ambient NO2 concentrations. However, this effect is not due to NO2 fixation but due to the canopy reduction/enhanced dry deposition rate, which also yields a reduction of other air pollutants. See e.g. Grundström and Pleijel [2014], Yang et al [2005], or Yang et al. [2008] for details.

The canopy reduction is also considered in recent regional modeling studies - see e.g. Arndt et al. [2016] (Disclaimer: I was member of that working group until recently). It can be seen like increasing the surface roughness.


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