Introduction to Contaminated Site Management - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 8

fallout (precipitation, gas phase and particulate matter), especially in winter, at
an urban site in Paris, France);

• metal deposition from lead smelters (e.g., Salemaa et al. ( 2004 ), who measured

elevated concentrations of metals in different plants, especially in bryophytes,
near a copper-nickel smelter in Harjavalta, Finland);

• traffic (e.g., Hjortenkrans et al. ( 2006 ), who measured elevated concentrations of

copper and antinomy due to decelerating activities, and lead and cadmium due to
the combustion of petrol, in top soils in the south of Sweden);

• incineration activities (e.g., Schuhmacher et al. ( 2000 ), who measured ele-

vated concentrations of Poly Chlorinated Dibenzo-p-Dioxins (PCDD) and Poly
Chlorinated Dibenzo Furans (PCDF) in soil and vegetation in the vicinity of an
old municipal solid-waste incinerator in Barcelona, Spain).

Metals and PAHs are known to be the most abundant and widespread contami-
nants worldwide.
Several other major contaminant sources are known to have contributed to large-
scale soil contamination, such as coal combustion and mining activities. Another
notorious source of contaminants, such as all kinds of petroleum hydrocarbons,
PAHs, BETX (benzene, ethylbenzene, toluene and xylenes), methyl- tert -butylether
(MTBE), and metals, is the oil industry, through oil exploration and production,
refining and petro-chemical activities. In Mexico, for example, the number of
reported hydrocarbon spills for the year 2000 exceeded 185 thousand, equivalent
to 6252 tons (Iturbe et al. 2005 ).
In agricultural areas, contaminants have been introduced by using soils for waste-
water filtering, applying sludge onto the soil, or applying ash from waste materials,
used for liming (e.g., Pasquini and Alexander ( 2004 ), who demonstrated an increase
of mainly lead through ash addition to soils on the Jos Plateau in Nigeria). Also
the application of mine waste contributed to soil and groundwater contamination
(e.g., Cobb et al. ( 2000 ), who demonstrated the presence of relatively high metal
uptake of lettuce and radishes in soils mixed with mine waste in Bingham Creek,
USA).
There also are many types of direct emissions. These direct emissions could
follow from unintentional leakage (leaching) from artificial layers applied for soil
surface-raising purposes, filling materials in construction works (dikes, roads) or
from old waste disposal landfills, gas stations or storage tanks. Another example
of an activity that generally caused contamination of soil and groundwater are
gas works. See Fig. 1.1 for a picture of the former gas works 'Delftse Wallen' in
Zoetermeer, the Netherlands, as an example, around 1908. At this site, heavy metals
and PAHs were found in the upper soil layer, due to soil surface-raising activities,
and aromatic contaminants, petroleum hydrocarbons and PAHs in the groundwa-
ter, in the late 20th century. Currently, a soil remediation is ongoing, the latest cost
estimate is 2 million euro.
Another type of direct emissions to soil is spilling of contaminants during
production processes, transport and storage. This often relates to (petro)chemical
industrial sites (e.g., Nadal et al. ( 2004 ) who measured elevated concentrations