Page 67 - Soil and water contamination, 2nd edition

54 Soil and Water Contamination

O Litter
O Humus
A
E Leached

B Accumulation

C Parent material

R Bedrock
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Figure 3.2 A generalised soil profile in a loamy soil in temperate humid regions.

about soil formation and classification, the reader is referred to standard textbooks on soil
science (e.g., Scheffer and Schachtschabel, 1989; Locher and De Bakker, 1990; Miller and
Gardiner, 2008; and Gerrard, 2000).

3.2.2 Sources of soil pollution

Input of pollutants into soil occurs via many pathways. The deliberate dumping of solid
or liquid wastes in heaps or tailing ponds is one of the most visible kinds of soil pollution.
Municipal, industrial, or mine wastes, or dug-up contaminated soil or sediments may
-
contain a wide range of pollutants, including metals , cyanide (CN ), polycyclic aromatic
hydrocarbons (PAHs), polychlorinated biphenyls (PCBs ), asbestos, methane (CH ),
4
ammonia (NH ), and hydrogen sulphide (H S), which may pose a threat to the surrounding,
3 2
unpolluted soil. Nowadays, the dispersal of pollutants from waste disposal sites is restricted
by means of a sustainable isolation of the site, but there are many former dump sites where
this isolation is absent or malfunctioning. Releases of industrial pollutants into soil may
also occur accidentally, for example as a result of road accidents or accidental spill s from
industrial installations. Liquid substances in particular can easily pollute large volumes of
soil, because they easily penetrate and disperse in soil. The soils of military training grounds
and battlefields are often contaminated by ammunition, bullets, explosives, fuels, and scrap
metals containing substances such as PAHs, lead , and depleted uranium .

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