Cycles Flashcards
nitrogen fixation
because atmospheric N2 cannot be used directly by plants it must first be converted into ammonia (NH3) by bacteria (rhizobium)
ammonification
decomposers convert organic waste into ammonia
nitrification
ammonia (NH3) is converted to nitrate ions (NO3-)
assimilation
inorganic nitrogen is converted into organic molecules such as DNA/amino acids and proteins
denitrification
bacteria convert nitrate (NO3-) and nitrite (NO2-) back into N2 gas
phosphorus does not circulate as easily as nitrogen because
it does not exist as a gas, but is released by weathering of phosphate [PO4(3-)]n rocks
how excess phosphorus is added back to aquatic ecosystems
runoff of animal wastes, fertilizer, discharge of sewage
largest reservoirs of C
carbonate [CO3(2-)] rocks first, oceans second