NSES Content Standard D 
Earth and Space Science: Geochemical cycles
Grades 9-12, page 189

The earth is a system containing essentially a fixed amount of each stable chemical atom or element. Each element can exist in several different chemical reservoirs. Each element on earth moves among reservoirs in the solid earth, oceans, atmosphere, and organisms as part of geochemical cycles.

Benchmark 5E The Living Environment: Flow of Matter and Energy
Grades 6-8, page 120
Over a long time, matter is transferred from one organism to another repeatedly and between organisms and their physical environment. As in all material systems, the total amount of matter remains constant, even though its form and location change.