<h2>NO2 uptake by plants</h2>

<p>It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations <a href="http://www.atmos-chem-phys.net/13/773/2013/" rel="nofollow noreferrer">[Breuninger et al, 2013]</a>. 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.</p>

<p>See <a href="http://www.atmos-chem-phys.net/13/773/2013/" rel="nofollow noreferrer">Breuninger et al. [2013]</a> and refernces therein for details</p>

<h2>Canpoy reduction</h2>

<p>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. <a href="http://www.sciencedirect.com/science/article/pii/S0269749114000773" rel="nofollow noreferrer">Grundström and Pleijel [2014]</a> for details.</p>

<h2>Impact on air quality</h2>

<p>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 <em>canopy reduction</em>/<em>enhanced dry deposition rate</em>, which also yields a reduction of other air pollutants. See e.g. <a href="http://www.sciencedirect.com/science/article/pii/S0269749114000773" rel="nofollow noreferrer">Grundström and Pleijel [2014]</a>, <a href="http://www.sciencedirect.com/science/article/pii/S1618866704000226" rel="nofollow noreferrer">Yang et al [2005]</a>, or <a href="http://www.sciencedirect.com/science/article/pii/S1352231008006262" rel="nofollow noreferrer">Yang et al. [2008]</a> for details.</p>

<p>The canopy reduction is also considered in recent regional modeling studies - see e.g. <a href="https://www.cmascenter.org/conference//2016/slides/arndt_implementation_canopy_2016.pdf" rel="nofollow noreferrer">Arndt et al. [2016]</a> (Disclaimer: I was member of that working group until recently). It can be seen like increasing the surface roughness.</p>

CC BY-SA 3.0
2016-12-30T07:33:03.427Z
2016-12-30T07:33:03.427Z
daniel.heydebreck
<p>Nitrogen dioxide (NO2) is a relevant air pollutant i.e. by contributing to the ozone (O3) production.</p>

<p>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.</p>

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

<p>Can anyone answer these questions? </p>

<p>Thanks</p>

CC BY-SA 3.0
2016-12-28T14:41:01.907Z
I'm voting to close this question as off-topic because it belongs in http://biology.stackexchange.com
arkaia
CC BY-SA 3.0
2016-12-28T14:49:50.380Z
I don't understand why, given that air quality questions are already in this forum.
Diego
CC BY-SA 3.0
2016-12-28T16:34:32.020Z
Then frame the question in terms of air quality, not just biology.
arkaia
CC BY-SA 3.0
2016-12-28T22:36:36.483Z
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.
Gordon Stanger
CC BY-SA 3.0
2016-12-28T23:17:39.813Z
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.
haresfur
CC BY-SA 3.0
2016-12-29T23:33:19.637Z
I don't think "fixation" is the appropriate term in that context. What you are looking for is dry deposition. I no longer have access to any material about the relevance of dry deposition for NO2 though
Christoph
<nitrogen><air-quality>
Are there plants or bacteria that perform NO2 fixation and how relevant are they for improving local/regional air quality?
Diego
# Are there plants or bacteria that perform NO2 fixation and how relevant are they for improving local/regional air quality?

(Asked by: username_0 on 2016-12-28)

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?

Thanks

**Tags:** nitrogen, air-quality

> **Comments:**
> **username_1**: I'm voting to close this question as off-topic because it belongs in http://biology.stackexchange.com  
> **username_0**: I don't understand why, given that air quality questions are already in this forum.  
> **username_1**: Then frame the question in terms of air quality, not just biology.  
> **username_2**: 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.  
> **username_3**: 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.  
> **username_4**: I don't think "fixation" is the appropriate term in that context. What you are looking for is dry deposition. I no longer have access to any material about the relevance of dry deposition for NO2 though  

---

## 1 answers

### Answer by username_5 on 2016-12-30. Score: 4

## NO2 uptake by plants

It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations [[Breuninger et al, 2013]](http://www.atmos-chem-phys.net/13/773/2013/). 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]](http://www.atmos-chem-phys.net/13/773/2013/) 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 username_4 stated in his comment. After deposition they may revolatilize or be washed down by rain. See e.g. [Grundström and Pleijel [2014]](http://www.sciencedirect.com/science/article/pii/S0269749114000773) 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]](http://www.sciencedirect.com/science/article/pii/S0269749114000773), [Yang et al [2005]](http://www.sciencedirect.com/science/article/pii/S1618866704000226), or [Yang et al. [2008]](http://www.sciencedirect.com/science/article/pii/S1352231008006262) for details.

The canopy reduction is also considered in recent regional modeling studies - see e.g. [Arndt et al. [2016]](https://www.cmascenter.org/conference//2016/slides/arndt_implementation_canopy_2016.pdf) (Disclaimer: I was member of that working group until recently). It can be seen like increasing the surface roughness.


---

