Matter returns through repeated transformations.
Operational definition
Earth-system process.
The repeated movement and chemical transformation of elements among living organisms and atmospheric, hydrologic, geological, and sedimentary reservoirs.
Examples include the cycles of:
- carbon;
- nitrogen;
- phosphorus;
- sulfur;
- iron;
- water.
Matter may be repeatedly reused, although individual atoms can remain sequestered for very long intervals.