| A | B |
|---|
| nitric oxide (NO) | produced by burning fuels at high temps |
| nitric acid (HNO3) | acid deposition |
| nitrogen fixation | requires special bacteria in soil or water |
| nitrogen gas (N2) | makes up most of the earth's atmosphere |
| nitrogen (N) | part of DNA and proteins |
| ammonia (NH3) | ammonia |
| ammonium (NH4) | can be used by plants |
| nitrification | bacteria convert NH3 and NH4 into nitrite |
| ammonification | decomposer bacteria convert organic material to N-containing inorganics |
| denitrification | N leaves soil through bacteria in waterlogged soil or oceans |
| nitrous oxide (N2O) | anaerobic bacteria breaking down livestock waste and fertilizers |
| nitrogen leaching | unused inorganic fertilizers leave the soil and contaminate water |
| deforestation | releases gaseous N compounds into the atmosphere from the soil |
| nitrates | enter aquatic systems by agricultural runoff |
| nitrogen in topsoil | released into air by agricultural practices |
| autotrophs | can directly use nitrogen as an energy sourtce |
