Environmental Engineering Reference
In-Depth Information
orders, described below, are of particular concern during field sampling.
2.3.1. Gelisol
The Gelisols are soils developing in parent material that is frozen most of the year. They
contain permafrost, which is a layer frozen for two or more years in a row within 100cm
of the surface. These soils are slow to develop and may show extreme mixing because of
freezing and thawing. Gelisols occur in the northern regions of Russia, Alaska, and
Canada. Because of the frozen layer and low temperatures contamination will not be
easily removed by natural processes.
2.3.2. Andisols
Andisols develop in volcanic ash and often contain 40-50% cinders, which are larger
than 2 mm in diameter. They are young soils that are poorly developed and have high
infiltration and percolation rates. Because of their high porosity and lack of profile
development pollutants may pass rapidly through them.
2.3.3. Histosols
Histosols are organic soils in the upper 80 cm of the soil profile containing organic matter
that can either be fully or partially decomposed. They develop in depressional areas under
water-saturated and anaerobic conditions. Organic matter has a high affinity for many
soil contaminants, and thus must be treated and analyzed differently than mineral soils.
2.3.4. Vertisols
Vertisols contain large amounts of expanding clays, and because of these clays develop
cracks that are 30 cm wide and 1 m deep when dry. When wetted the cracks close.
During dry periods surface material falls into the cracks, thus producing an inverted soil.
Not only can soil and organic matter fall into these cracks, but also pollutants. This is
important to keep in mind when sampling. Remediation of these soils is difficult because
water moves through them extremely slowly and the cracks allow pollutants to penetrate
deeply into the soil.
2.3.5. Aridisols
Aridisols occur in arid climates, and because there is little rainfall these soils tend to have
high pHs, usually above 7.5, and are often affected by salts. This means that pollutants
will react differently in these soils when compared to acid soils. The salts will affect
remote sensing, particularly ground penetrating radar (GPR), and both the sampling and
analysis of samples from these soils.
2.3.6. Spodosols
Spodosols occur in acid, sandy soils and develop under conifer (cone-bearing trees
 
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