Geology Reference
In-Depth Information
3.2 Urban pollution
Urban pollution includes runoff from impervious surfaces, misleadingly
termed rainwater, residues from treatment of collected liquid domestic
pollution, and residues from treatment of household waste.
Roofing collects the airborne fraction of unburnt heating oil
(hydrocarbons, sulfates), and paved surfaces (roads, parking lots) collects
hydrocarbons (lubricants), suspended particles (dust from brakes and
clutches), heavy metals (zinc from paint, and previously lead from fuel), salt
during the winter. Rain following a dry period washes out the pollutants
on paved surfaces.
Residues from treating household waste include ash from incinerators
(in the favorable event that incineration is total, air pollution is still a
concern), and residue from smoke scrubbers (REFIOM). If these easily-
leached residues, likely to return numerous mineral (heavy metals, salts)
or organic (dioxins) pollutants to the environment, are sometimes stored
in impermeable sites, where effl uents are collected and treated, some were,
for a long time, dumped into vulnerable areas (example: sinkholes of the
Besançon limestone plateau). They are still currently used to build road
embankments.
3.3 Industrial pollution
Diverse in its composition, industrial pollution includes liquid effl uents,
leakage from storage areas or pipelines, and solid residue which has often, in
the past, been used to build embankments. Although the liquid effl uent now
undergoes specifi c, effective treatment, leaks are still diffi cult to detect and
control, and abandoned sites result in industrial wastelands with polluted
soil likely to contaminate any underlying aquifer. For example, in the Rhone
valley, an aquifer covered by such material now produces, for a water
union supplying 200,000 consumers, water polluted by methylbenzenes
and chlorinated solvents.
3.4 Agricultural pollution
Agriculture can produce point pollution, such as leakage from livestock
farming by-products: manure and silage effl uent, or fertilizer or plant
protection product spills, during the preparation of material to be spread or
the rinsing of material. In addition, the fertilizers and pesticides spread onto
fi elds make up a diffuse pollution source, the vegetation and soil serving as
a pollutant reservoir, easily mobilized by infi ltrating water. This pollution
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