<p>For other readers of this topic who did not look into the manual which is available <a href="https://www.camx.com/Files/CAMxUsersGuide_v6.50.pdf" rel="nofollow noreferrer">here</a>: There is chapter 5.1 on &quot;classical&quot; gas phase chemistry, 5.2 on aerosol chemistry and 5.3 on mercury chemistry.</p>
<p>Generally, the mercury chemistry is quite complex which is also indicated by the first sentences of the first paragraph of chapter 5.3:</p>
<blockquote>
<p>Mercury exists in the atmosphere as elemental mercury, Hg(0), and oxidized mercury, Hg(II) (Schroeder and Munthe, 1998). Hg(II) can be inorganic (e.g., mercuric chloride, HgCl2) or organic (e.g., methyl mercury, MeHg). It can also be present as particulate mercury (e.g., mercuric oxide, HgO, or mercury sulfide, HgS)</p>
</blockquote>
<p>Classical gas phase chemistry mechanisms (Carbon Bound; SAPRC) do not include mercury. There is no self-contained mercury chemistry &quot;package&quot;/mechanism available which can be simply referenced like e.g. Carbon Bound IV for gas phase chemistry. Instead, the full mercury mechanism implemented in CMAx has to be described.</p>
<p>Mercury chemistry does not only take place in the gas phase or in the aerosol phase but in both phases. Additionally, a general introduction on mercury chemistry and an implementation description were necessary. Hence, splitting the description of the mechanism into two parts -- on in chapter 5.1 and another in chapter 5.2 -- would not have been reasonable.</p>
<p>Moreover, it is an optional feature which can be ignored for many air quality studies whereas the content of chapters 5.1 and 5.2 are relevant for most air quality studies.</p>

CC BY-SA 4.0
2024-08-07T21:32:16.710Z
2024-08-07T21:32:16.710Z
daniel.heydebreck
<p>studying the manual (user guide) of CAMx 6.50, a fact that really imprressed me is that there is a subsection in chemistry mechanisms for chemistry of mercury. Thus, I would like to ask why the authors have given this importance to Mercury.</p>

<models><air-pollution>
Subsection for mercury in camxuserguide 6.50
Dimitris Tsiaousidis
# Subsection for mercury in camxuserguide 6.50

(Asked by: username_0 on 2024-08-02)

studying the manual (user guide) of CAMx 6.50, a fact that really imprressed me is that there is a subsection in chemistry mechanisms for chemistry of mercury. Thus, I would like to ask why the authors have given this importance to Mercury.

**Tags:** models, air-pollution


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## 1 answers

### Answer by username_1 on 2024-08-07. Score: 1

For other readers of this topic who did not look into the manual which is available [here](https://www.camx.com/Files/CAMxUsersGuide_v6.50.pdf): There is chapter 5.1 on "classical" gas phase chemistry, 5.2 on aerosol chemistry and 5.3 on mercury chemistry.

Generally, the mercury chemistry is quite complex which is also indicated by the first sentences of the first paragraph of chapter 5.3:

> Mercury exists in the atmosphere as elemental mercury, Hg(0), and oxidized mercury, Hg(II) (Schroeder and Munthe, 1998). Hg(II) can be inorganic (e.g., mercuric chloride, HgCl2) or organic (e.g., methyl mercury, MeHg). It can also be present as particulate mercury (e.g., mercuric oxide, HgO, or mercury sulfide, HgS)

Classical gas phase chemistry mechanisms (Carbon Bound; SAPRC) do not include mercury. There is no self-contained mercury chemistry "package"/mechanism available which can be simply referenced like e.g. Carbon Bound IV for gas phase chemistry. Instead, the full mercury mechanism implemented in CMAx has to be described.

Mercury chemistry does not only take place in the gas phase or in the aerosol phase but in both phases. Additionally, a general introduction on mercury chemistry and an implementation description were necessary. Hence, splitting the description of the mechanism into two parts -- on in chapter 5.1 and another in chapter 5.2 -- would not have been reasonable.

Moreover, it is an optional feature which can be ignored for many air quality studies whereas the content of chapters 5.1 and 5.2 are relevant for most air quality studies.


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