Environmental Engineering Reference
In-Depth Information
Pollution of large urban centres nevertheless remains difficult to control
due to the constant rise in the number of vehicles, despite the technical
advances made. This is especially true in the developing countries.
Significant pollution remains at regional level, due in particular to the
presence of sulphur in the fossil fuels (coal, heavy fuel oil). Emissions of
sulphur and nitrogen oxides contribute atmospheric pollution, leading to
acid rain which is harmful for forests and lakes. The atmosphere is also
polluted by soot and tar emitted by vehicles or industrial facilities, carbon
monoxide resulting from incomplete combustion, unburnt hydrocarbons
and volatile organic compounds (VOCs) from the evaporation or incom-
plete combustion of fuels.
In Asia, industrial pollution caused by development of the economy
produces, between April and October, a vast brown cloud consisting of
sulphur-containing aerosols mixed with carbon monoxide, ozone, nitro-
gen oxides, soot and dust. This cloud reduces solar radiation and rain by
20% to 40%.
Progress is also underway in this area, both as regards the technical
solutions and applicable regulations. TheGothenburg protocol, approved
by the United Nations in 1999, plans a 75% reduction in sulphur dioxide
(SO 2 ) emissions and a 49% reduction in nitrogen oxide (NO x ) emissions
compared with the 1990 levels [6].
Amongst the problems encountered, sea pollution related to the trans-
port of crude oil receives high media coverage. The consequences of oil
spills caused by the accidental sinking of tankers are highly visible, but
represent only a relatively small fraction of all hydrocarbon spills at sea.
The number of oil spills is in fact steadily decreasing.
The number of accidental oil spills at sea has been divided by 10 over the
last 30 years, whilst since 1980 maritime oil traffic has increased by 80%.
In addition, the accelerated introduction of double hull tankers has
reduced even further the risk of oil slicks. In contrast, deliberate discharges
due in particular to tank cleaning, which are difficult to observe and
punish, continue and represent a major source of oil pollution at sea.
The risks for the environment are not restricted to fossil fuels. The
development of nuclear energy also raises a certain number of problems.
The risks involved are not easy to estimate, since they are generally
related to accidental phenomena rather than to normal operation.
Consequently, the level of danger for the environment and the public is
a subject of heated debate. It is related to the management of radioactive
waste and to accidental leakage of toxic products throughout the produc-
tion chain.
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