GEOG 1200 Lecture Notes - Lecture 4: Phosphorus Cycle, Nitrogen Cycle, Nitrogen Fixation
5 Dec 2016
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Document Summary
Availability of energy and matter are highly variable from place to place and account for the diversity of life of earth. Limiting factors = physical, chemical and biological characteristics that restrain population growth: for example, plant productivity (e. g. photosynthesis) is limited by the requirement in least supply. Light (radiant energy) is a limiting factor. Environmental resistance = all limiting factors taken together. The flow of matter in the biosphere: nutrients: elements and compounds required for survival that are consumed by organisms (biogeochemical cycle) Sedimentary cycles: nutrients spend much of their time locked up in rock but are released for use by life as a result of weathering processes. Gaseous cycle: nutrients spend much if their time in the atmosphere. Nutrients are exchanged b/w the biosphere and the atmosphere. Our wastewater discharge is also very high in phosphates: nitrogen cycle, input, nitrification: ammonium ions are converted in nitrite ions and then into nitrate ions.
