Environmental Science (2+1)

Nitrogen cycle

 
• About 78 percent of the atmosphere is nitrogen gas (N2), but in this molecular form it is not active in biological systems. The nitrogen must first be fixed in the form of nitrates (NO3-), in which form it can be utilized by plants during photosynthesis. Eventually, it is combined with other substances and converted into proteins, consumed by heterotrophs and broken down again in the process of decay. Nitrification, the process in which nitrogen in the form of ammonia (NH3) is converted to nitrate nitrogen, is of particular significance in water pollution control