EAS100 Lecture Notes - Lecture 33: Biogeochemical Cycle, Nitrogen Fixation, Nitrogen Cycle

• School: University of Alberta
• Department: Earth and Atmospheric Sciences
• Course: EAS100
• Professor: Korhan Ayranci

Document Summary

A biogeochemical cycle describes the movement of a chemical element or compound. Cycle may include the geosphere, hydrosphere and/or atmosphere as well as the through the biosphere and the rest of the earth system biosphere. Periodic table showing elements required for living organisms. Macronutrients: required by all living things in large amounts (big six: c, h, o, n, p, s) Micronutrients: small amounts for all life or required by some living things. Also occurs in oxidized n 2 o (nitrous oxide) and as nitrate ions no 3 . Also occurs in reduced forms as ammonia nh 3 . 90% done by nitrogen-fixing bacteria called nitrogen fixation. Once converted, taken up by plants and algae, and consumed by animals. Upon death, bacteria convert nitrogen compounds back to n 2 . By denitrification, and it returns to atmosphere. Essential to living processes; often a limiting nutrient. Essential to biosphere: forms part of helical framework of dna and facilitates life"s.