2.3.2—Cycle components
- Syllabus
- First assessment 2026
- Objective
- 2.3.2
- Level
- HL
Use Input and Output to Find a Sink or Source
Compare total input I with output O: I>O means net accumulation (sink), O>I means net release (source), and I=O means balance.
The label describes the net flux during the chosen time interval. A store can change role when conditions or rates change.
A wetland receives 12 units of carbon and releases 9, so 3 units accumulate: it is a net sink for that interval.
Source, with net release of 3 units; do not keep the old label after rates change.
A sink is not an empty store—it is a store whose input exceeds output over the period measured.