ENVR 200 Lecture Notes - Lecture 9: Hydrogen Sulfide, Oxidative Phosphorylation, Methanogenesis

• School: McGill University
• Department: Environment
• Course: ENVR 200
• Professor: George Mc Court

Document Summary

Photosynthesis produces high energy c compounds from low energy co2. C is reduced, has electrons added and becomes more negative. Photosynthesis links atmosphere (co2), the energy budget (sunlight) and the biosphere. Some microorganisms use other electron donors and acceptors than c and o. Sulfur oxidation: hydrogen sulfide -> sulfur + water, sulfur -> sulphate. Carbohydrates, lipids and proteins can be broken down by all organisms. Cellulose is not easily digestible (only microbes with cellulase can digest it) Lignin can only be digested by a few fungal groups. Biomass stored on land as lignocellulose is not easily accessed, as it is hard to digest. Energy is lost at each step in the food chain. Terrestrial biomes store lots of carbon in vegetation and soil, unlike marine biomes. Higher c turnover in marine biomes, slower c turnover in terrestrial biomes. Food webs demonstrate the complexity of systems, but don"t include everything. Organisms also produce waste materials, which go back into the cycle.