| A | B |
|---|
| Nitrogen fixing | Because atomospheric N cannot be used directly by plants it must first be converted into ammonia by bacteria |
| Ammonification | decomposers covert organic waste into ammonia |
| Nitrification | amonia is converted to nitrate ions |
| Assimilation | inorganic N is converted into organic molecules such as DNA/ammino acids and protiens |
| Dentirification | bacteria convert ammonia back into N |
| Phosphorus does not circulate as easily as N because | it does not exist as a gas, but is released by weathering of phosphate rocks |
| sustainability | the ability to meet humanities current needs without comprimising the ability of future generations to meet their needs |
| Excess phosphorus is added to aquatic ecosystems by | runnoff of animal wastes, fertilizer, discharge of sewer |
| Photosynthesis | plants convert atmospheric C(CO2) into complex carbohydrates (glucose C6H12O6) |
