Industrial metabolismIndustrial metabolism is a concept to describe the material and energy turnover of industrial systems. It was proposed by Robert Ayres in analogy to the biological metabolism as "the whole integrated collection of physical processes that convert raw materials and energy, plus labour, into finished products and wastes..." In analogy to the biological concept of metabolism, which is used to describe the whole of chemical reactions in, for example, a cell to maintain its functions and reproduce itself, the concept of industrial metabolism describes the chemical reactions, transport processes, and manufacturing activities in industry.
Aquatic ecosystemAn aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic (slow moving water, including pools, ponds, and lakes); lotic (faster moving water, for example streams and rivers); and wetlands (areas where the soil is saturated or inundated for at least part of the time).
Open system (systems theory)An open system is a system that has external interactions. Such interactions can take the form of information, energy, or material transfers into or out of the system boundary, depending on the discipline which defines the concept. An open system is contrasted with the concept of an isolated system which exchanges neither energy, matter, nor information with its environment. An open system is also known as a flow system. The concept of an open system was formalized within a framework that enabled one to interrelate the theory of the organism, thermodynamics, and evolutionary theory.
