Nutrient Cycling Recycling Water, Nitrogen, and Carbon
The Water Cycle The water cycle is the process by which water is purified and recycled in our atmosphere.
The Water Cycle Evaporation moves water from the earth’s surface (oceans, lakes, streams) to the atmosphere in the form of water vapor. Transpiration is another form of evaporation as plants lose moisture from their leaves. Condensation results when cooler air meets water vapor causing clouds to form. Precipitation occurs when too much water vapor is condensed in the clouds. Precipitation returns water to the earth’s surface in the form of rain, snow, sleet, and hail.
The Carbon Cycle All life is carbon based.
The Carbon Cycle Carbon is recycled through the process of respiration. Plants use CO2 and release O2. Animals use O2 and release CO2. Carbon is also recycled during the process of decomposition. The carbon contained in dead organisms is released into the atmosphere as it decays. Fossil fuels are stores of ancient carbon over millions of years.
The Nitrogen Cycle 78% of the atmosphere is nitrogen.
The Nitrogen Cycle Nitrogen is an essential component of many organic molecules such as DNA, RNA, and proteins. Nitrogen (N2) gas found in the air is not usable in that form. It must be “fixed.” Nitrogen fixation is when nitrogen gas is converted by bacteria into a useable form for plants.
Nitrogen Fixation There are specialized bacteria whose function it is to fix nitrogen, converting it so that it can be used by plants. There are still other bacteria who do the reverse so that nitrogen can be turned back into its gaseous from. After nitrogen is fixed, it can be absorbed and used by plants and then by animals.