ABSTRACT
Thus far the present text has focused on basic principles and issues of ecotoxicology. These have been illustrated by taking examples of particular types of pollutants describing environmental problems that they have caused. In this chapter some wider issues will be addressed, some of which have been touched upon in earlier chapters. Phenomena like global warming caused by greenhouse gases and thinning of the ozone layer are matters of international concern that need to be resolved through international cooperation (Chapter 7). This also applies to the problem of acid rain, which is discussed in the same chapter. Sulfur dioxide has been a major contributor to acid rain in the northern hemisphere, and questions have been asked about its role in damaging forests and acidifying lakes (Howells 1995). North America and Scandinavia have been particularly affected, and there has been political discussion about the extent to which the export of sulfur dioxide from one country to another has been responsible. With time, emissions of sulfur dioxide and other gases contributing to acidification of rain have been reduced-notably since the fall of communism. The Gaia theory is a concept that attempts to look at natural processes and cycles in a holistic way, considering the earth to be a single self-regulating entity. Hopefully the use of models of this kind will help to resolve global pollution problems.
