Anthropogenic metabolism seen through the lens of entropy

The great ecological challenges in coming decades require a solid understanding of the processes ofanthropogenic metabolism, which must be transformed in such a way that the protection of people and the environment and the careful use of natural resources is guaranteed as much as possible. This understanding includes quantitative and qualitative aspects. While the quantitative aspects can be described well with the method of material flow analysis, the qualitative aspects of a material flowsystem are more difficult to grasp. 

In thermodynamics, the entropy law is used to assess the quality of energy conversion processes. Similarly, statistical entropy is proposed for evaluating the quality of material transformation processes. The concept assesses how a system mixes or separates substances. Material flow analyses describe any anthropogenic process (technology, industrial branch, region) using substance concentrations and mass flows. 

One can now show that these processes can be represented as something that transforms distributions of concentrations and mass flows. The extentof the transformation can be quantified by statistical entropy. Concentrating processes (e.g. recycling) are shown as reducing entropy and polluting emissions as producing entropy. 

Statistical entropy can be used in a very versatile way since many material questions can be reduced to the assessment of concentration / mass distributions. This is illustrated using some examples: A comparison of different agricultural regions shows that animal-based agriculture does worse in terms of environmental pollution from nitrogen compounds compared to plant-based agriculture. A comparison of the globaluse of Cu and Zn shows that they differ significantly in that Zn is used in a much more dissipative manner. 

An analysis of the anthropogenic phosphorus balance shows that even with comprehensive optimization it will be very difficult to realize a sustainable form of use. Statistical entropy can also beused to assess the efficiency of recycling processes and the recyclability of products. Entropy is a very reliable indicator and can help in the search for sustainable solutions.