3.2.3.2 Selection of Main Factors of Pollution Mitigation of Vadose
Zone
(1) Selection basis
The main processes that affect the migration and transformation of pollutants in the
vadose zone include convection, dispersion, adsorption and degradation. The
combined effects of these processes will ultimately affect the time taken for pollutants to reach groundwater and the concentration of pollutants in groundwater.
Therefore, when selecting the main factors of pollution mitigation of vadose zone,
priority is given to factors affecting the migration rate and concentration attenuation
of pollutants. In addition, the main factors should be easy to obtain and quantifiable.
Based on the above principles, the main factors are identified for four categories
of vadose zone.
(2) Main factors by vadose zone categories
(a) Monolithologic type
Four factors are selected, of which maximum pollution thickness, permeability of
rocks and soils, and adsorption of rocks and soils measure the impact on the
duration of pollutant migration, and degradability of rocks and soils measures the
impact on pollutant concentrations.
Maximum pollution thickness (M) defines the maximum distance that pollutants
may migrate in the vadose zone (Fig. 3.15), which denotes the vertical distance
from the location of discharge by pollution sources to the groundwater table. Where
Fig. 3.15 Schematic diagram
of maximum pollution
thickness
3.2 Method of Groundwater Pollution Source Intensity Rating …
55
Zone
(1) Selection basis
The main processes that affect the migration and transformation of pollutants in the
vadose zone include convection, dispersion, adsorption and degradation. The
combined effects of these processes will ultimately affect the time taken for pollutants to reach groundwater and the concentration of pollutants in groundwater.
Therefore, when selecting the main factors of pollution mitigation of vadose zone,
priority is given to factors affecting the migration rate and concentration attenuation
of pollutants. In addition, the main factors should be easy to obtain and quantifiable.
Based on the above principles, the main factors are identified for four categories
of vadose zone.
(2) Main factors by vadose zone categories
(a) Monolithologic type
Four factors are selected, of which maximum pollution thickness, permeability of
rocks and soils, and adsorption of rocks and soils measure the impact on the
duration of pollutant migration, and degradability of rocks and soils measures the
impact on pollutant concentrations.
Maximum pollution thickness (M) defines the maximum distance that pollutants
may migrate in the vadose zone (Fig. 3.15), which denotes the vertical distance
from the location of discharge by pollution sources to the groundwater table. Where
Fig. 3.15 Schematic diagram
of maximum pollution
thickness
3.2 Method of Groundwater Pollution Source Intensity Rating …
55