Deposition dust particle

L Fixed-bed, or packed-bed, filters. These units are not cleaned when they become plugged with deposited dust particles but are broken up for disposal or simply abandoned. If they are constructed from fine granules (e.g., sand particles), they may be designed to give high collection efficiencies on fine dust particles. However, if such a filter is to have a reasonable operating life, it can be used only on a gas containing a low concentration of (Just particles. 

Two other deposition mechanisms, in addition to the six listed, may be in operation under particular circumstances. Some dust particles may be collected on filters by sieving when the pore diameter is less than the particle diameter. Except in small membrane filters, the sieving mechanism is probably limited to surface-type filters, in which a layer of collected dust is itself the principal filter medium. 

The spherical packings are too large to serve as effective targets for the deposition of fine dust particles. In dust-coUection service, the packings actually serve as tumulence promoters, while the dust particles are collected primarily by the liquid droplets. 

Diffusion—dust particles deposited on the liquid droplets. Predominant for the submicron and particles up to about 5p. 

A small flux is shown between the land and atmosphere. This represents the transport of dust particles to the atmosphere (F28) and the deposition of these particles back on land either as dry deposition or associated with atmospheric precipitation (F82). Similarly, fluxes that represent the transport of seasalt from the surface ocean to the atmosphere (Fss) and the deposition of soluble (F85) and insoluble (F81) atmospheric forms are also shown. As already discussed for the river fluxes, the insoluble particulate flux is represented as a direct transport of P to the sediment reservoir. 

Mining and industrial activities produce large quantities of volatiles and dust particles and increase concentrations of trace elements and heavy metals in soils, waters, and vegetation. When mineral deposits containing concentrated trace elements and heavy metals are exposed at the earth s... 

---