Biogeochemical Cycles Biogeochemical Cycles describe the flow of
Biogeochemical Cycles
Biogeochemical Cycles describe the flow of essential elements from the environment through living organisms and back into the environment.
What Sustains Life on Earth? • Solar energy, the cycling of matter, and gravity sustain the earth’s life.
Water Cycle (Hydrologic Cycle)
Hydrological Cycle
Hydrological Cycle 1. Reservoir – oceans, air (as water vapor), groundwater, lakes and glaciers; evaporation, wind and precipitation (rain) move water from oceans to land. 2. Assimilation – plants absorb water from the ground, animals drink water or eat other organisms which are composed mostly of water. 3. Release – plants transpire, animals breathe and expel liquid wastes.
Organism’s Role • Intake of water: Organisms take in water and use it to perform life functions (such as photosynthesis or transport of nutrients). • Transpiration: Plants release water back into the atmosphere through the process of transpiration (the evaporative loss of water from plants).
Organism’s Role • Respiration: All organisms metabolize food for energy and produce water as a byproduct of respiration. • Elimination: Most organisms need water to assist with the elimination of waste products.
Carbon Cycle
CO 2 & CH 4
Carbon Cycle
Carbon Cycle (carbon is required for building organic compounds) 1. Reservoir – atmosphere (as CO 2), fossil fuels (oil, coal, natural gas), durable organic materials (for example: cellulose). 2. Assimilation – plants use CO 2 in photosynthesis; animals consume plants. 3. Release – plants and animals release CO 2 through respiration and decomposition; CO 2 is released as wood and fossil fuels are burned.
Organism’s Role • Photosynthesis: • Photosynthetic organisms take in carbon dioxide from the atmosphere and convert it to simple sugars. Respiration: Organisms break down glucose and carbon is released into the atmosphere as carbon dioxide.
• Organism’s Role • Conversion of • Decomposition: When biochemical organisms die, compounds: decomposers break Organisms store down carbon as compounds which both carbohydrates, enrich the soil or proteins, lipids, aquatic sediments and nucleic acids are eventually released in their bodies. into the atmosphere as carbon dioxide.
Organism’s Role • Combustion: When wood or fossil fuels (which were formed from once living organisms) are burned, carbon dioxide is released into the atmosphere. • Weathering of carbonate rocks: When sedimentary rocks weather and decompose, carbon is released into the ocean and eventually into the atmosphere.
Nitrogen Cycle
Nitrogen Cycle
50% fertilizer (Bacteria)
Nitrogen Cycle
Nitrogen Cycle 1. Reservoir – atmosphere (as N 2); soil (as NH 4+ or ammonium, NH 3 or ammonia, N 02 - or nitrite, N 03 - or nitrate 2. Assimilation – plants absorb nitrogen as either NH 4+ or as N 03 -, animals obtain nitrogen by eating plants and other animals. 3. Release – Denitrifying bacteria convert N 03 - back to N 2; detrivorous bacteria convert organic compounds back to NH 4+ ; animals excrete NH 4+, urea, or uric acid.
Organism’s Role • Nitrogen-fixation: Nitrogen-fixing bacteria, which are found in the soil, root nodules of plants, or aquatic ecosystems, are capable of converting elemental nitrogen found in the air or dissolved in water into the forms that are available for use by plants • Intake of nitrogen: Plants take in the nitrogen through their root systems in the form of ammonia or nitrate and in this way, nitrogen can enter the food chain.
Organism’s Role • Decomposition: When an organism dies or from animal waste products, decomposers return nitrogen to the soil. • Denitrification: Denitrifying bacteria break down the nitrogen compounds in the soil and release elemental nitrogen, N 2, into the atmosphere.
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