Deposition Velocity

Question 1

What is deposition velocity?

Answer 1

1. Considered the flux of reactive gas to surface in terms of volume of gas (m3) per surface area (m2) per unit time (s)
2. An extent to which a solid surface interacts with gas (Vdeposition)
3. Expresses ability of surface to take up pollutant gas

Question 2

What are the units of Vd?

Answer 2

m3m-2s-1 to ms-1

Question 3

What does the Vd depend on and how does it change?

Answer 3

Depends on a gas’s reactivity with the surface, eg:
1. Ozone on activated charcoal - reactive, high Vd
2. NO2 on inert glass - less reactive, low Vd

Question 4

What is an application of Vd?

Answer 4

Prediction of I/O ratios of pollutant gases

Question 5

What do the values of Vd range from?

Answer 5

0.001 (ozone on glass) - 2.5 (SO2 on cement)