Principle IV- There are no Permanent or Impermeable Boundaries that Prevent Matter from Flowing between Systems
The exchange of matter between natural systems and human societies affects the long-term functioning of both. As a basis for understanding this principle:
- Students need to know that the effects of human activities on natural systems are directly related to the quantities of resources consumed and to the quantity and characteristics of the resulting byproducts.
- Students need to know that the byproducts of human activity are not readily prevented from entering natural systems and may be beneficial, salve neutral, order or detrimental in their effect.
- Students need to know that the capacity of natural systems to adjust to human-caused alterations depends on the nature of the system as well as the scope, there scale, and duration of the activity and the nature of its byproducts.
Example: The fertilizers and pesticides people use on lawns can enter the groundwater system and affect the quality of the drinking water supply.