Ontology: Natural Order
Neighbours: land time climate biotope person
Components: substances water sand & gravel carbon fossil fuels timber paper nutrients steel aluminium fertiliser solvents heavy metals pesticides hazardous chemicals

Source: Measuring material flow and resource productivity - synthesis report. Technical report, OECD, Paris, France, 2008 (Box 2 on page 16).

Substances

What: chemical elements or compounds such as Cd, Pb, Zn, Hg, N, P, CO₂, CFC.

Type of analysis: Substance flow analysis and accounts (SFA) monitor flows of specific substances that are known for raising particular concerns as regards the environmental and health risks associated with their production and consumption.

Materials

What: Selected raw materials or semi-finished products at various levels of detail and application (e.g. cement, paper, iron and steel, copper, plastics, timber, water).
Type of analysis: Material system analysis (MSA) is based on material specific flow accounts. It considers life-cycle-wide inputs and outputs. It applies to materials that raise particular concerns as to the sustainability of their use, the security of their supply to the economy, and/or the environmental consequences of their production and consumption.

Flows

It is useful to distinguish between "bulk" and "toxic" flows.