Nutrient cycle

4. Conversion of nitrates back into nitrogen gas by anaerobic denitrifying bacteria in waterlogged soils.
6. Microorganisms that break down dead organisms and waste products, releasing mineral ions (like phosphates) back into the soil.
9. Increased nutrient concentration (e.g., nitrates) in water bodies, leading to rapid algal growth, blockage of light, and death of aquatic plants/organisms.
10. Production of ammonia/ammonium ions from organic nitrogen-containing compounds (proteins, urea, DNA) in dead/waste matter by saprobionts.
11. The breaking down of sedimentary rocks, releasing phosphate ions into soil and water.

1. Process converting atmospheric nitrogen gas into nitrogen-containing compounds (e.g., ammonia) by bacteria in the soil or root nodules.
2. Natural (manure) or artificial (inorganic) nutrients added to soil to replace those lost during crop harvesting.
3. Fungal associations with plant roots that increase the surface area for water and mineral ion (especially phosphate) absorption, acting like a sponge.
5. Waste matter from birds/bats rich in phosphate ions.
7. Oxidation of ammonium ions to nitrites to nitrites by nitrifying bacteria in aerobic conditions.
8. The process where water-soluble nutrients (like nitrates) are washed from the soil into watercourses by rain.