Page 17 - Soil and water contamination, 2nd edition

4 Soil and Water Contamination

policies to protect and improve the quality of the environment by preventing, controlling,
and abating environmental pollution. In 1972, the United Nations established the United
Nations Environmental Programme (UNEP) with its headquarters in Nairobi, Kenya. In
1991, the European Union set up the European Environmental Agency in Copenhagen,
Denmark. Since the 1970s and 1980s, environmental protection and pollution control
measures have increasingly been incorporated into national and supranational legislation, for
example the Nitrate Directive (91/676/EC) and the Water Framework Directive (2000/60/
EC) of the European Commission, implemented in 1991 and 2000, respectively. Although
much has been achieved to abate and control environmental pollution in the western world,
the United Nations Millennium Ecosystem Assessment (2005) has demonstrated that at
the global scale, substantial changes are required to mitigate the negative consequences of
growing pressures on ecosystems. However, pressures on land resources have continued to
increase during recent years, despite international commitment and resolve to improve the
management of the resources. Similarly, many water bodies are still affected by pollution, and
many emerging contaminants have poorly understood effects (UNEP, 2012).

1.2 ENVIRONMENTAL POLLUTION

Before further discussing the issues related to environmental pollution, it would be useful to
clarify some terminology. Pollution and contamination are used synonymously to mean the
introduction into the environment by humans of substances that are harmful or poisonous to
people and ecosystems. These substances (called pollutants or contaminants) are, therefore,
anthropogenic, that is, they result from human activities. However, anthropogenic does not
mean that all pollutants are man-made or synthetic chemicals, such as DDT or plutonium ;
chemical compounds that occur naturally in the environment can also be anthropogenic.
In fact, the most widespread environmental pollution involves ‘natural’ compounds (for
example, carbon dioxide ) and fertilisers (such as nitrate ). Furthermore, pollution is not
restricted to substances, but can also refer to energy wastes, such as heat, light, and noise. In
all cases, pollution alters the chemical, physical, biological, or radiological integrity of soil
and water by killing species or changing their growth rate, interfering with food chains, or
adversely affecting human health and well-being.
Note that some experts distinguish between pollution and contamination. They use the
term contamination for situations where a pollutant is present in the environment, but not
causing any harm, while they use the term pollution for situations where harmful effects are
apparent (see Alloway and Ayres, 1997). However, the distinction between contamination
and pollution may not be clear, because harmful effects may be present but unobserved. The
above definition of pollution and contamination avoids this problem, so in this book the two
terms are used interchangeably.
Human activity is unevenly distributed over the world; the Earth’s surface, too, is
variable by nature. As a result, the intensity and consequences of environmental pollution
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vary from place to place. Of the 136 million km land surface on Earth, about 10 percent is
used as arable land and 25 percent consists of productive pasture and of forests that might
be converted into agricultural land. The pursuit of ever-higher agricultural yields, which
has been made possible through technological innovation and the cultivation of marginal
areas, has resulted in widespread degradation of agricultural land. In the past half-century,
40 percent of the world’s agricultural land has been degraded by accelerated erosion by
wind and water, salinisation , compaction, nutrient exhaustion, pollution, and urbanisation
(Millennium Ecosystem Assessment, 2003). Moreover, the excess application of fertilisers
and pesticides contaminates groundwater and surface water via leaching and contaminates
the soil of natural areas next to agricultural land via atmospheric deposition . The increased

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