Nitrogen In The Nation's Rain

Nitrogen is essential for all living things. Nearly 98% of the world's nitrogen is found in the solid earth within the chemical structure of rock, soil, and sediment. The remainder moves in a dynamic cycle involving the atmosphere, oceans, lakes, streams, plants, and animals. Small amounts of the nitrogen in soil and sediment also enter this complex cycle. Molecular nitrogen (N2) is a colorless odorless gas that comprises 78% of our atmosphere. Nearly 8 metric tons of nitrogen sit atop every square meter of the earth's surface. Molecular nitrogen is stable and converting it to other chemical compounds requires considerable energy. A lightning bolt provides sufficient energy to do the job, causing some nitrogen and oxygen in the air to form nitrogen oxides. Photosynthetic energy in plants and chemical energy in soil microorganisms also can convert nitrogen to other chemical forms. All of these natural processes occur in the cycling of nitrogen in our environment.