GGR227H5 Lecture Notes - Lecture 4: Anthropocene, Soil Retrogression And Degradation, Ion
Document Summary
Ggr227 lecture 4 global climate & environmental. Finishing cycling of matter (n, p and s cycles, acid deposition) Most organisms cannot directly receive atmosphere nitrogen. Nitrogen fixation takes nitrogen from atmosphere transforming it into ammonia: is step 1 can be done abiotic, through lightning, carried out by bacteria. Ammonium is taken and converted into nitrate through process of nitrification: nitrification soil bacteria changes ammonia and ammonium ions into nitrate ions - plants use nitrate ions as nutrient. Decomposition (re-mineralization) converting organic form of nitrogen into a mineral form. Denitrification converts nitrate ions into gas form: returns nitrogen to atmosphere. Caused the doubling of atmospheric nitrogen being fixed. Assimilation and decomposition also called uptake and mineralization connect abiotic nitrogen reservoirs with biotic parts of the ecosystem. No atmospheric form of phosphorus mainly locked up in rock: phosphorus must be mined in order to use it. Is a dominant limiting factor in most ecosystems especially freshwater ecosystems.
