The present understanding of Earth’s global anthrobiogeochemical metal cycles

Comprehensive anthrobiogeochemical metal cycles that incorporate material flow through the natural, social, and interfacing system have been constructed to illustrate the interacting geomorphic forces of human activity. As the purveyor of what is arguably the Anthropocene epoch, human society has a responsibility to manage the movement of these metals in a way that preserves their sustained availability while minimizing the potential impacts on the natural environment. Global metal cycles constructed for aluminum (Al), iron (Fe), copper (Cu), zinc (Zn), silver, nickel, lead, and chromium quantify how humans at the beginning of the twenty-first century have come to cause approximately half the metal mass mobilization on Earth. For the industrial metals of Al, Fe, Cu, and Zn, ∼1–5% of the Earth’s land surface now has metal flow dominated by people. These traditionally mined metals are accumulating as in-use stock in highly concentrated bands in the developed world, a secondary resource available for recovery through recycling. The pattern of ore depletion and translocation to in-use stock accumulation highlights an implicit metal material wealth transfer from the developing to developed world, having long-term implications for understanding which parts of the world actually hold the wealth of “natural” metal resources. Further, this research highlights the human–nature interfaces of metal mass flows that should be the target of environmental management. Copyright Springer-Verlag 2012