(introduction...)
Even theoretically it would be impossible to keep all contaminants
out of all water everywhere; even without human influences contamination of
bodies of water has always occurred and will continue to occur. To take an
example, we need only think of the compounds which can be formed in lakes under
certain conditions, such as hydrogen sulfide (H2S), which causes most of the
organisms within the affected zone to die off, or at the very least causing
oxidophilic organisms to avoid such polluted aquatic environments. If there is
excessive introduction of allochthonous organic matter and/or in-situ production
of organic substances, hydrogen sulfide is formed, for instance on the bottom of
lakes, when the oxygen content is no longer sufficient for mineralization of
organic materials by aerobic processes. Studies of the earth's history have
revealed that water pollution of this kind has often happened even without human
beings playing a role. The question here is, what possibilities are available
for detecting temporary and longerlasting positive and negative changes in water
bodies? What possibilities exist for identifying and, if possible, predicting
latent and acute threats caused by water pollution and thus of offering means of
dealing with or warding off these threats? Science is only capable of providing
the know-how and tools. Conflicts of interests often lead to these warnings and
indications being ignored, as is shown by the example of the salinization of the
Nile delta and the resulting drastic decline in Egyptian marine fishery yields
caused by the construction of the Aswan Dam. These repercussions were predicted
by scientists of repute, but were ignored by the decision makers. The rerouting
of the Nile in Sudan and the laying dry of the Sudd (the "Jongley Canal"
project) would have had catastrophic effects for the population living there if
they had not succeeded in preventing this measure at the last moment. That the
industrialized nations are also still burdened by problems of this sort is
illustrated by the example of the Rhine. The quality of the water flowing in the
Rhine has improved since the report of the Council of Experts for Environmental
Issues (Rat von Sachverstandigen fur Umweltfragen) (4) in the Federal Republic
of Germany, but it is still far from satisfactory. Heavy metal contamination of
the river even seems to be increasing again. However, this fact does not relieve
us of our responsibility to warn the developing countries of the dangers of
water pollution and to call attention to means of detecting and avoiding such
pollution. This of course also includes the provision of training and
technological
know-how.
