Environmental Systems and Societies · Topic 2: Ecology

ES2.3 — Biogeochemical cycles

Environmental Systems and Societies · SL / HL · syllabus-mapped notes

1. Stores, sinks, sources and the carbon cycle

   How cycles keep elements available, the store/sink/source distinction, residence time, and the flows that move carbon between stores.

2. Carbon, oceans and human impact

   Agricultural soils as sinks or sources, ocean uptake and acidification, and at least three measures to alleviate human effects on the carbon cycle.

3. The nitrogen cycle

   Organic and inorganic nitrogen stores, the essential bacterial processes, denitrification in anaerobic soils, and mutualistic nitrogen fixation.

4. Nitrogen: human impact and the planetary boundary

   How human activities and the Haber process alter the cycle, why the nitrogen planetary boundary is crossed, and the collaboration needed.

5. HL: Lithosphere carbon stores and methane

   Long-residence carbon in rocks and fossil fuels, limestone from marine hard parts, fossil-fuel formation, and methane from methanogenic bacteria.