GGR227H5 Lecture Notes - Lecture 4: Denitrification, Nitrification, Ammonia
Document Summary
We have greatly increased the amount of n cycling at the surface of the earth through the industrial fixing of atmospheric n2to produce nh3(ammonia) for fertilizers haber- 3 h2+ n2 2 nh3: this has resulted in an approximate doubling of the amount of atmospheric n2being fixed (natural n cycle vs. present day, even natural/pristine ecosystems are experiencing n fertilization" as a result. Biological interactions: living organisms (particularly microorganisms, also larger animals) are very important drivers of global biogeochemical cycles, e. g. , salmon bring p and n nutrients from marine ecosystems to freshwaters when they spawn, die and decompose, releasing nutrients. Bears facilitate transfer from salmon to forest: box 8. 5. Sulfur (s: like all macro-nutrients, an essential component for life, a building component of proteins, s rarely a limiting factor" in ecosystems. H2s (gas): produced in wetlands in absence of oxygen, rotten egg smell, escapes to the atmosphere. Scientific metrics of planetary transformations owed to humanity: atmosphere and ecosystems.
