Circulation of Nutrients Provides:

1. Circulation of Nutrients Provides: essential elements for processes like photosynthesis, building amino acid and nucleic acids etc decomposition releases minerals and nutrients for metabolic processes

3. Decomposition • Dead or waste organic matter converted to inorganic nutrients • Un-decomposed material is litter • fully decomposed material is humus • physical and biological process • detritovores - detritus eating invertebrates • microbial decomposers - bacteria/fungi • fixed, lost and transformed nutrients

4. Detritus converted to humus (small pieces of material more easily broken down by microbes Decomposition rates influenced by: type of detritus type / abundance of decomposers environmental conditions e.g. temp, moisture, aeration, nutrient availability Mineralisation – release of minerals essential for life

5. Nutrient Cycling nutrients required by living organisms plants from soil animals from ingested material nutrients can be macro or micro macro nitrogen, carbon, phosphorus, (sulphur) trace elements, zinc, magnesium, iron, etc. micro

6. Nutrient Cycling nutrients in biogeochemical cycles fixed in biotic and abiotic components taken up or lost by absorption or leaching chemically transformed by biological or environmental processes

9. Nitrogen cycle (80% stable) converted by redox reactions to useful compounds 5 main steps • Biological nitrogen fixation • gaseous nitrogen converted to ammonia • Rhizobium bacteria (free living or symbiotic in nodules in legumes) • prokaryotic bacteria or cyanobacteria

10. Biological nitrogen fixation • anaerobic conditions, needs energy • enzyme nitrogenase. • leghaemoglobin in nodule bacteria fixes oxygen giving anaerobic conditions

12. Nitrification • ammonia converted to nitrates by soil involves many bacterial groups Nitrosomonas/Nitrococcus convert ammonia to nitrites Nitrobacter oxidises nitrites to nitrates (energy release)

14. 3. Assimilation Initial uptake of ammonia/nitrates by primary producers to make protein/nucleic acids. Consumers eating at various trophic levels 4. Ammonification Decomposition to produce ammonia by bacteria in soil and aquatic ecosystems 5. Denitrification Nitrates converted to nitrogen gas by free living anaerobic denitrifyng bacteria (agrobacterium and psuedomonas)

16. Loss of soluble nutrients

17. Loss of soluble nitrates by leaching and run-off Limits to nitrogen in environment Water saturation creating anaerobic conditions reduces nitrification Tropical rainforest decomposition is rapid but soil quality is poor due to scarcity of humus and litter, leaching removes nutrients quickly Temperate forest decomposition slower, soil quality is good as litter and humus in plentiful supply Crop rotation and addition of fertilizers

18. Carbon cycle

19. Phosphorus cycle

20. Phosphorus nucleic acids, phospholipids, ATP, minerals in bones and teeth local cycling of phosphate bound by humus and soil particles occurs as phosphates in soils from weathered rocks plants take up phosphates and assimilate it animals consume phosphorus and assimilate it animals excrete, organisms die and decomposition returns phosphorus to soil

21. Eutrophication Results from too much phosphorus or nitrogen in aquatic ecosystems plants and algae grow rapidly and die decomposition of plant material uses lots of oxygen from water other organisms e.g. fish unable to survive low oxygen levels