The cryosphere encompasses the frozen parts of Earth, including glaciers and ice sheets, sea ice, and any other frozen body of water. The cryosphere plays a critical role in regulating climate and sea levels. (source #8)

The Geosphere is associated with solid portions of the Earth. It includes the continental and oceanic crust and all other layers of the Earth's interior. This includes all rocks, sediments and soils, surface landforms and the processes that shape the Earth's surface.(source #12)

The Hydrosphere is associated with water in the liquid state, which covers about 70% of the Earth's surface. Most liquid water is found in the oceans. Our Hydrosphere gives Earth a distinct appearance as a blue marble and separates us from other planets in the solar system. (source #12)

magma, molten or partially molten rock from which igneous rocks form. It usually consists of silicate liquid, although carbonate and sulfide melts occur as well. Magma migrates either at depth or to Earth’s surface and is ejected as lava. Several interrelated physical properties determine the characteristics of magma, including chemical composition, viscosity, dissolved gases, and temperature. (source # 7)

As these organisms die, certain microbes such as detritivores are able to participate in the decomposition of organic nitrogen into ammonia (ammonification), providing a constant supply of ammonia to be used in the process of nitrification. (source #7)

Nitrates and ammonia resulting from nitrogen fixation are assimilated into the specific tissue compounds of algae and higher plants. Animals then ingest these algae and plants, converting them into their own body compounds. (source #7)

reduction of nitrates or nitrites commonly by bacteria (as in soil) that usually results in the escape of nitrogen into the air. (source #5)

Nitrogen is fixed, or combined, in nature as nitric oxide by lightning and ultraviolet rays, but more significant amounts of nitrogen are fixed as ammonia, nitrites, and nitrates by soil microorganisms. More than 90 percent of all nitrogen fixation is effected by them.(source #7)

Groundwater is water that exists underground in saturated zones beneath the land surface. The upper surface of the saturated zone is called the water table. (source #15)