<p>Sulfate is one important inorganic aerosol in the atmosphere. It's subject to removal by two main mechanisms.   </p>

<ol>
<li>Wet deposition which include rain/wash-out and cloud deposition.    </li>
<li>Dry deposition which include impaction,diffusion,gravitational settling and etc.</li>
</ol>

<p>This <a href="http://www.aos.wisc.edu/uwaosjournal/Volume22/Karambelas_MSThesis.pdf" rel="nofollow noreferrer">master thesis</a> says:    </p>

<blockquote>
  <p>Sulfate aerosol, in particular, is heavily impacted by dry deposition, which accounts for 40% of the total sulfur deposition on average (Baumgardner et al., 2002; Butler &amp; Likens, 1995) and up to 55% of total sulfur deposition in forested regions (Linderg &amp; Lovett, 1992).<br>
  Aerosol dry deposition depends on wind speed, solar radiation, and the type and condition of ground cover (Sheih et al., 1979).   </p>
</blockquote>

<p>But I'm confused about the status of forested region, which have the high relative humidity, frequent rain, and more surface the aerosol can condense on (cloud deposition process: In high elevation ecosystem, the cloud droplets can be interception by vegetation). In my opinion, it should enhance the wet deposition of sulfate</p>

<p><strong>Does someone know why the dry deposition perform better in forested regions?</strong></p>

CC BY-SA 3.0
2016-02-21T22:51:18.000Z
Forests provide biogenic emissions that provide a chemical pathway that allows for more sulfate aerosol to be produced.  So, the total percentage of deposition that is "dry" increases, since you've converted more gaseous SO2 to an aerosol.
f.thorpe
CC BY-SA 3.0
2016-02-21T23:41:36.077Z
Gravitational settling of small particles is difficult if you have strong winds and turbulence all the way down to the ground. Forests provide a way to have a relatively still boundary layer in which gravity can act. It also provides a ground covered in vegetation, leaves, etc, that further shelters small particles that have settled.
Wolfgang Bangerth
<atmosphere><geochemistry><atmospheric-chemistry><air-pollution>
Dry deposition of the total sulfate deposition in forested region
Han Zhengzu
# Dry deposition of the total sulfate deposition in forested region

(Asked by: username_0 on 2016-02-21)

Sulfate is one important inorganic aerosol in the atmosphere. It's subject to removal by two main mechanisms.

1. Wet deposition which include rain/wash-out and cloud deposition.
2. Dry deposition which include impaction,diffusion,gravitational settling and etc.

This [master thesis](http://www.aos.wisc.edu/uwaosjournal/Volume22/Karambelas_MSThesis.pdf) says:

> Sulfate aerosol, in particular, is heavily impacted by dry deposition, which accounts for 40% of the total sulfur deposition on average (Baumgardner et al., 2002; Butler & Likens, 1995) and up to 55% of total sulfur deposition in forested regions (Linderg & Lovett, 1992).  
> Aerosol dry deposition depends on wind speed, solar radiation, and the type and condition of ground cover (Sheih et al., 1979).

But I'm confused about the status of forested region, which have the high relative humidity, frequent rain, and more surface the aerosol can condense on (cloud deposition process: In high elevation ecosystem, the cloud droplets can be interception by vegetation). In my opinion, it should enhance the wet deposition of sulfate

**Does someone know why the dry deposition perform better in forested regions?**

**Tags:** atmosphere, geochemistry, atmospheric-chemistry, air-pollution

> **Comments:**
> **username_1**: Forests provide biogenic emissions that provide a chemical pathway that allows for more sulfate aerosol to be produced.  So, the total percentage of deposition that is "dry" increases, since you've converted more gaseous SO2 to an aerosol.  
> **username_2**: Gravitational settling of small particles is difficult if you have strong winds and turbulence all the way down to the ground. Forests provide a way to have a relatively still boundary layer in which gravity can act. It also provides a ground covered in vegetation, leaves, etc, that further shelters small particles that have settled.  

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## 0 answers

