Heavy Metals in the Environment: A Geoschience Perspective

Naturally occurring heavy metals may be transported through the atmosphere over long distances; perhaps hundreds or even thousands of kilometres. Such metals can also be derived from man-made (anthropogenic) sources. A number of nnational and international organizations have been established whose aim is to address increasing environmental and public concerns over the effects such metals may have on ecosystems in remote areas of the world. These concerns result principally from an apparent consensus in the environmental literature that heavy metal concentrations in these areas have increased significantly in relation to naturally occurring background levels as a result of long-range atmospheric transport of metals from industrial sources. Arecent review of literature published over the last 25 years on this and related topics indicates that in some cases there has been insufficient attention paid to whether metals in the environment are of industrial or naturalorigin, and that there remains substantial uncertainty over the role played by natural sources of metals in the atmospheric transport system. There remains a critical lack of representative data on natural metal releases into the atmosphere, but without this information it is difficult to estimate with any degree of accuracy the respective contributions made by natural and industrial sources to total global metal emissions. Natural background concentrations and cycling processes must be known in order to assess the extent and impact of industrial releases of metals to the environment, be it on a global, regional or local scale. There is thus an urgent requirement for further research into quantifying metal emissions from both natural and industrial sources, and into the most appropriate methodologies that may be applied to obtaining increased accuracy in such estimates. A well-coordinated, systematie effort is required to collect representative information so that abetter understanding of long-range atmospheric metals transport and its environmental effects can be achieved.