The sum of the total material input and the hidden or
indirect material flows, including deliberate landscape
alterations. It is the total material requirement for a national
economy, including all domestic and imported natural resources.
The TMR gives the best overall estimate for the potential
environmental impact associated with natural resource extraction
and use.
Hidden material flow
The portion of the TMR that
never enters the economy. It is the natural resource use that
occurs when providing those commodities that do enter the
economy.
Hidden flows occur at the harvesting or extraction stage of the material
cycle.
The hidden material flow comprises two components,
ancillary flows and excavated and/or disturbed flows, even though these
two components can have markedly different environmental impacts.
For the purposes of physical accounting -- in system terminology --
hidden flows represent a simultaneous input and output.
Domestic Hidden Flows (DHF)
The total weight of materials moved or mobilized in the domestic environment
in the course of providing commodities for economic use, which do not
themselves enter the economy.
Ancillary material flow
This is the material that must be removed from the natural
environment, along with the desired material, to obtain the
desired material. Examples of this category
include:
the portion of a ore that is processed and discarded to
concentrate the ore
the plant and forest biomass that is
removed from the land along with the logs and grain, but is
later separated from the desired material before further
processing.
Excavated and/or disturbed material flow
This is material moved or disturbed to obtain a natural resource,
or to create and maintain infrastructure. Included in this category:
the overburden that must be removed to permit access to an ore
body
the soil erosion from agriculture
the material moved in the construction of infrastructure, such as
a highway or building, or in the dredging of harbors and canals
Direct Material Input (DMI)
This is the flow of natural resource commodities that enter the
industrial economy for further processing. Included in this category
are:
grains used by a food processor
petroleum sent to a refinery
metals used by a manufacturer
logs taken to a mill
Domestic Processed Output (DPO)
The total weight of materials, extracted from the domestic environment
and imported from other countries, which have been used in the domestic
economy, then flow to the domestic environment.
These flows occur at the processing, manufacturing, use, and final
disposal stages of the economic production-consumption chain.
Included in DPO are:
emissions to air from commercial energy combustion (including
bunker fuels) and other industrial processes
industrial and household wastes deposited in landfills
material loads in the wastewater
materials dispersed into the environment as a result of
product use (see dissipative flows below)
emissions from incineration plants
Exported materials are excluded because their wastes occur in
other countries. Recycled material flows in the economy (e.g., metals,
paper, and glass) are subtracted from DPO. An uncertain fraction
of some dissipative use flows (manure, fertilizer) is recycled by plant
growth, but no attempt has been made to estimate this fraction and
subtract it from DPO.
Total Domestic Output (TDO)
The sum of domestic processed output and domestic hidden flows.
This indicator represents the total quantity of material outputs
to the domestic environment caused directly or indirectly by human
economic activity.
Gateway flows
The share of DPO, or TDO, which exits the economy by each of
three environmental gateways: air, land, and water.
Gateways are the first point of entry of a material flow
into the environment.
Both DPO and TDO can be disaggregated to show the quantity,
and major constituents, of material flows to air, land, and water;
gateway flows are a means of differentiating material flows in
order to provide more information about their potential
environmental impacts.
Sector flows
The share of DPO, or TDO, which can directly be attributed to the
activities of individual economic sectors such as:
industry (manufacturing and mining)
agriculture
energy supply (utilities)
construction
transport
household
Both DPO and TDO can be disaggregated to show the quantity of
material output generated by each sector.
Dissipative flows
The quantity (weight) of materials dispersed into the environment
as a deliberate, or unavoidable (with current technology), consequence
of product use.
These flows comprise two components:
Dissipative uses such as fertilizers and manure spread
on fields, and salt spread on roads.
Dissipative losses such as rubber worn away from car
tires, particles worn from friction products such as brakes and
clutches, and solvents used in paints or other coatings.
Dissipative uses can be part of:
an ultimate throughput (e.g., mineral fertilizer)
part of recycling (e.g., manure, compost, and sewage applied
on fields for nutrient recycling)
Net Additions to Stock (NAS)
The quantity (weight) of
new construction materials used in
buildings and other infrastructure
materials incorporated into new durable goods (such as cars,
industrial machinery, and household appliances)
New materials are added to the economy's stock each year
(gross additions) and old materials are removed from stock as
buildings are demolished and durable goods discarded. These
decommissioned materials, if not recycled, are accounted for
in DPO. The balance is the net addition to stock.
