Materials Flow Cycle
- In U.S, more than 4 billion pounds of toxic chemicals were released by industry into air, land and water in 2004, including 72 million pounds of recognized carcinogens.
- Persistent chemical compounds are of global concerns as they cycle through ecosystem which includes humans. This is even more harmful to children, pregnant women, and the elderly.
- Reliance on nonrenewable resources is also another concern with the use of materials. •Renewable resource is any natural resource that is depleted at a rate slower than the rate at which it regenerates.
- 99% of the original material used in the production of or contained in U.S. goods becomes waste within six weeks of sale. The majority of which comes from nonrenewable resources, especially petroleum, which adds to environmental and human health impacts.
Flow of raw materials in U.S by weight
Source: MINING ENGINEERING, DECEMBER 2002, 17
- Built environment is where we live, work, shop, study and play. e.g., buildings, roads, bridges etc.
- Built environment requires tremendous amount of water, energy, and natural resources for its construction and operation.
- Approximately 85% of the U.S. material flow by weight is associated with items such as aggregate, cement, steel reinforcement, and wood. (water is not included in this analysis, if included, it would be the single largest material flow).
- Built environment affects local heating of the urban area – ‘urban heat island’.
- Also affects the water that cycles through highly urbanized watersheds (many along east coast of U.S).
- Moving out of urban centers creates sprawl, which causes problems too (high energy and material requirement, fragmentation of habitat).
- Smart growth or new urbanism is a new initiative.