Elemental cycles: a status report on human or natural dominance

Abstract

The modern technological society mobilizes and uses a very large number of materials. These substances are derived from rocks, sediments, and other natural repositories, and most undergo transformation prior to use. A large fraction of the materials is eventually returned to the environment. Natural processes do the same but not necessarily with the same suite of materials. For purposes of better understanding industrial development and potential environmental impact, it is important to know, even approximately, the elemental cycles of all materials potentially useful for modern technology. In this review, we examine and summarize cycle information for 77 of the first 92 elements in the periodic table. Mobilization calculations demonstrate that human activities likely dominate or strongly perturb the cycles of most of the elements other than the alkalis, alkali earths, and halogens. We propose that this pattern is ultimately related to the aqueous solubilities of the predominant chemical forms of the elements as they occur in nature: Human action dominates the cycles of the elements whose usual forms are highly insoluble, nature those that are highly soluble. Examples of the utility of anthropogenically dominated cycle determinations for resource supply analyses, environmental impact assessment, and public policy are presented and discussed. If the rapid rise in the use of materials by the technological society in the twentieth century continues into the next century, anthropogenic dominance of the cycling of a majority of the elements of the periodic table will only increase.