The long-term ecological effects of pollutants; some issues

In this paper we consider the long-term ecological effects of pollutants using three case-studies as examples: 'acid rain' and its effects on forests, soil and aquatic ecosystems; excess nitrogen deposition from the atmosphere and its effects on natural vegetation, and increased emission of CO2 and its possible climatic and ecological consequences. We point out that the scale of pollution arising from natural human functions is considerable given the size of the world human population. Additions to this background from industrial processes can be reduced considerably by technical means, but not eliminated entirely. The same 'contaminants' associated with industrial energy consumption (SO2, NOx, CO2) are also produced by natural processes. The sum of these three sources gives rise to a considerable 'irreducible' minimum background pollution level: the ecological consequences of this need to be explored further.