Geoscience Reference
In-Depth Information
Fig. 8.52 The movement of
water into a soil depends on
land surface slope,
vegetation, degree of surface
loading, and soil texture,
structure, density, and
compaction. More water
moves into the soil zone on
natural landscapes compared
to urban landscapes with
disturbed soils. These
schematic drawings compare
the generalized disposition
and movement of incoming
water on a natural plant-
covered landscape a with that
in a disturbed urban
landscape and b with limited
vegetation and abundant
impervious surfaces (Lyons
and Harmon
2012
; modified
after Scheyer and Hipple
2005
)
and vegetation (Fig.
8.52
). Urbanization strongly affects the physical and hydro-
logical regime of a natural soil-subsurface and may completely change the
pathway of disposed contaminants.
Two specific groups of chemical contaminants that are retained in soil-sub-
surface systems are heavy metals and metalloids, and petroleum hydrocarbons.
Several examples involving these chemicals are discussed here, being represen-
tative of urban contamination.
Arsenic contamination of soil-subsurface systems is of great environmental
concern. Chirenje et al. (
2003
) examined arsenic contamination in urban and
nonurban areas in Florida (USA). Arsenic presence was determined in 440 urban
and 448 uninhabited locations; the distribution of arsenic concentrations is pre-
sented in Fig.
8.53
. In general, arsenic concentrations in urban areas were higher
than those in uninhabited areas. The differences between the two urban sites are
due to their specific land uses. The authors noted that soil arsenic concentration in
the nonurban areas showed significant correlation with natural soil properties,
because
they
were
exposed
to
a
lower
disturbance
than
urban
soils.
As
a
