biogeochemical cycles - nitrogen

N2 in atmosphere

completely unusable by everything except nitrogen fixing bacteria

nitrogen fixing bacteria

in soil, water, plant roots (legumes)

nitrogen fixiation

done by nitrogen fixing bacteria, takes unusable N2 and creates usable NO3

assimilation

plants use NO3 to make proteins

dead plants broken down to create ______

ammonium - NH4

dentrificiation

taking usable nitrogen NO3 and making it unusable N2, so it can keep cycling

nitrification

converts ammonium NH4 to nitrite NO2 to nitrate NO3

eutrophication

excess plants growth due to excess nitrogen, takes all the oxygen, fish die due to lack of nitrogen, decomposers use oxygen to break down dead fish, plants die due to lack of oxygen, creating dead zone