Page 82 - Soil and water contamination, 2nd edition

Part II

Sources, role, and behaviour of substances in

soil and water

How persistent and toxic pollutants are in natural environments depends largely on their
physical and chemical behaviour. Pollutants can dissolve and precipitate, be adsorbed onto
particulate matter, or decompose; these biogeochemical processes are influenced by the
presence of other substances or organisms, generally referred to as environmental conditions.
When assessing the hazards and risks associated with the toxicity and dispersal of pollutants
in soil, groundwater, and surface waters, it is essential to understand the biogeochemical
behaviour of pollutants (e.g. their solubility, affinity to particulate matter, and decay rates)
under varying environmental conditions. Part II therefore provides a summarising overview
of the natural occurrence and anthropogenic sources, environmental role, physico-chemical
characteristics, and toxicity of the major polluting substances. These substances are described
one by one, according to a common classification based on their natural occurrence and role,
or their physical and chemical characteristics.

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