Material concentrations are highly skewed, with many deposits of low concentration and a few deposits of high concentration. Since materials are cycled by energy, and energy is hierarchically organized, materials are organized similarly, in hierarchies, with decreased quantities at each level of scale in inverse relation to concentration. . . “Emergy per unit mass is inverse to the quantity. Materials of high value are scarce because more energy is required to make them. . . Part of the environmental problems of our time appears to result from displacement of chemical substances from their normal position in the energy hierarchy” (Odum, 2007, p. 120-22).
Self-organization gets additional performance by concentrating materials in ways in which the concentrations reinforce. However, the greater the concentration the more energy is required per unit weight and the less material can be upgraded. For a system with constant empower, the quantity of material which can be processed in successive steps to a high emergy level is inverse to the energy per mass. Thus higher concentrations are scarce because of the nature of the energy hierarchy and its coupling to materials. . . Materials of different kinds are found coupled with different levels of the energy hierarchy spectrum (below). Theoretically, more system performance results and a material contributes more when it interacts with energy that it can mutually amplify. By that concept, designs for material flows develop where energy flows interact with flows of somewhat higher or lower transformity. The kind of hierarchical pattern of material processing may be at very different ranges of the energy hierarchy spectrum for different materials. Many heavy metals, for example, tend to go to the top of the biological range (Odum, 1999, p. 14).
“The ultimate effect of a pollutant or toxin is not only related to its transformity, but more importantly to its concentration or empower density (emergy per unit area per unit time, i.e. seJ/m2*day) in the ecosystem. Where empower density of a stressor is significantly higher than the average empower density of the ecosystem, it is released into, one can expect significant changes in ecosystem function. For instance, because of the very high transformities of most metals like those at the bottom of the table [below], their concentrations need be only in the parts per billion range to still have empower densities greater than most natural ecosystems” (Ulgiati & Brown, 2009, p. 318).
Genoni et al. (2003) calculated transformities for 25 elements in the Steina River in Germany (in the table above) and found the tendency to bioaccumulate according to the transformity of both the elements and of the accumulating compartments. Thus, metals and heavy elements accumulated in the high transformity trophic compartments of the river.
The growth of our civilization in the last two centuries has been based on rapid use of stored earth reserve of materials and energy. Since we are using the reserves of materials that had been accumulated by earth processes faster than they are being replaced, they are called nonrenewable. (They are actually very slowly renewed.) When the nonrenewable reserves are less, construction will depend on the reuse and reprocessing type of recycle, but these require fuels and services that also become limited (Odum, 1999, p. 47).