Biogeochemical Cycles PDF

## The Nitrogen Cycle - The air is composed of ~77% diatomic nitrogen. - Nitrogen is essential for life because it is a component of amino acids, nucleic acids, and ATP, the intercellular energy transfer molecule. - Neither plants nor animals can obtain nitrogen directly from the atmosphere, they r...

## The Nitrogen Cycle - The air is composed of ~77% diatomic nitrogen. - Nitrogen is essential for life because it is a component of amino acids, nucleic acids, and ATP, the intercellular energy transfer molecule. - Neither plants nor animals can obtain nitrogen directly from the atmosphere, they require the process of nitrogen fixation. - Legumes, such as clover, peas, alfalfa, soy beans, and peanuts, have evolved a symbiotic relationship with the diazotroph bacterium. - These bacteria reside in the root nodules of the legumes and convert nitrogen in the soil to ammonia (NH3) which can be taken up by the plant. - The nitrogen fixation into ammonia (NH3) is called ammonification. - After ammonification, chemolithotrophic bacteria convert the ammonia into nitrate in the process of nitrification. - The Nitrosomonas bacterium convert the ammonia into nitrite (NO2). - The Nitrobacter bacterium convert the nitrite into nitrate (NO3) which plants can use. - Plants are then consumed and the nitrogen is used in the synthesis of organic compounds such as amino acids, proteins, and nucleic acids. - Decomposers do denitrification where nitrates are broken down, and nitrogen is released into the atmosphere. ### Procedure 1. Atmosphere (A) Blue 2. N2 absorbing into ground (B) Purple 3. Nitrogen fixing bacteria (D) Red 4. Ammonification (E) Yellow 5. Consumption by plants (I) Green 6. Consumption by animals (J) Orange 7. Denitrification (K) Brown ### Answer Questions 1. What process makes nitrogen available to plants and animals? - Nitrogen Fixation 2. For what do organisms use nitrogen? - Organisms use nitrogen to make organic compounds 3. Describe the nitrogen cycle. - Nitrogen is fixed from the atmosphere by bacteria into ammonia. - Plants absorb ammonia and convert it into nitrates. - Animals eat the plants, and the nitrogen is passed on. - When organisms die, decomposers break down the organic matter and release nitrogen back into the environment. - Some nitrogen is lost through denitrification, where bacteria convert nitrates back into N2 gas. ## The Phosphorous Cycle - Phosphorus is an element in organic compounds. - Phosphorus is a component of adenosine triphosphate used in photosynthesis and is the sugar phosphate of nucleic acid, and the phospholipid in cell membranes. - The atmosphere is not involved in the phosphorous cycle. - Phosphorus becomes concentrated in marine sediment as a result of primary producers incorporating phosphates in organic compounds. - When consumers eat the producers, the phosphate is used in the production of bones and scales. - As marine sedimentary rock is upthrusted from beneath the water, it is exposed to weathering and erosion. - As the dissolved phosphorus combines with oxygen, it forms phosphate. - The phosphate then runs off into water where they are absorbed by plants and used to synthesize organic molecules. - Plants concentrate phosphate, which is then eaten by consumers. - Phosphate is returned to the water as plant and animal waste. ### Procedure 1. Erosion from rock (A) Blue 2. Absorption by Plants (B) Green 3. Consumption by animals (D) Orange 4. Plant and animal waste (F, G) Brown 5. Run off to ocean (H) Yellow 6. Marine sediment (I) Pink 7. Geologic Upthrust (J) Red ### Answer Questions 1. Is phosphorus an element in organic compounds? - Yes 2. Where is the store of phosphorus? - The store of phosphorus is mainly located in rocks, soil, and marine sediment. 3. Describe phosphorous cycle. - Phosphorus is released from rocks through weathering and erosion and is then absorbed by plants. - Animals eat the plants, and the phosphorus is passed on to them. - When organisms die, decomposers break down the organic matter, releasing phosphorus back into the environment. - Some phosphorus runs off into the ocean, where it becomes incorporated into marine sediment. - Over time, the marine sediment can be uplifted, returning phosphorus to land. ## Background: Biogeochemical Cycles - In ecology, a biogeochemical cycle is the circulation of matter through the biotic and abiotic components of an ecosystem. - The substances are recycled or accumulated in sinks. - The Earth is a system of interacting spheres: atmosphere, hydrosphere, lithosphere, and biosphere where energy and mass are cycled between them. ## The Water Cycle - Water is the most abundant substance in living organisms. - Evaporation is the process by which water changes into vapor and enters the atmosphere from soil and water on the surface. - The atmosphere includes clouds, which contain water vapor. - When water vapor cools, it condenses and gravity pulls the water to the Earth as rain, sleet, and snow. - Precipitation occurs over land as well as the ocean. - Water is absorbed by plant roots and used in photosynthesis. - Water is lost through plant leaves by transpiration. - Precipitated water enters the ocean by surface and subsurface run off. - The oceans are the major store of water, containing ~97% of the Earth's water. - Over 80% of the evaporated water enters the atmosphere from the oceans. - Of the water that is precipitated, ~52% fall into the oceans; the remainder remains in the atmosphere as vapor, clouds, and ice crystals that precipitate over land. ### Procedure 1. Precipitation over land (A) light blue 2. Precipitation over ocean (B) dark blue 3. Transpiration (C) red 4. Evaporation from ocean (F) orange 5. Surface run off (E) green 6. Subsurface run off (D) brown ### Answer Questions 1. What process removes CO2 from the atmosphere? - Photosynthesis 2. Describe transpiration. - Transpiration is the process by which plants release water vapor into the atmosphere through tiny pores in their leaves called stomata. 3. Describe water cycle. - Water evaporates from the surface of the Earth. - The water vapor rises into the atmosphere, where it cools and condenses to form clouds. - The water falls back to Earth as precipitation (rain, snow, sleet, or hail). - Some precipitation flows over land as surface runoff, while some soaks into the ground. - Groundwater can flow into rivers, lakes, and oceans, or it can evaporate directly from the ground. - Water also evaporates from the surface of oceans, lakes, and rivers. ## The Carbon-Oxygen Cycle - Producers (autotrophs) produce organic compounds from inorganic elements. - Producers are consumed by consumers (heterotrophs). - Decomposers (saprotrophs) break down organic material and release it back to the environment. - During photosynthesis, plants use solar radiation, carbon dioxide, and water to produce sugar and oxygen. - In respiration, animals react sugar and oxygen to produce water, energy, and carbon dioxide. - The decomposers feed on dead organic material and return carbon to the atmosphere as carbon dioxide. - High temperature and pressures over time can convert carbon-containing organic matter into coal, oil, and natural gas. - When these fossil fuels are burned, one product is carbon dioxide which is returned to the atmosphere. - Burning wood also produces carbon dioxide. - Dissolved carbon dioxide in the oceans combines with calcium to form calcium carbonate, which is incorporated into the shells of marine organisms. - The hydrosphere, lithosphere, and biosphere are the Earth's major stores of carbon in the form of dissolved carbon dioxide and organic molecules. - The largest store of oxygen is within minerals of the Earth's crust and mantle. - Oxygen is highly reactive and readily bonds with other elements. - The reacted oxygen contains 99.5% of the total oxygen. - Free oxygen in the biosphere is ~0.01% and in the atmosphere is 0.36%. ### Procedure 1. CO2 (A) Yellow 2. O2 (D) Blue 3. Photosynthesis (B) Green 4. Respiration by Plants (C) Red 5. Plant consumption (E) Dark Blue 6. Respiration by Animals (G) Light Blue 7. Animal waste and decay (H) Brown ### Answer Questions 1. Where is the store of oxygen? - Oxygen is stored in the Earth's crust and mantle in the form of minerals. - Some oxygen is dissolved in the oceans. - Oxygen is also found in the atmosphere 2. In what are carbon atoms? - Carbon atoms are found in all living things, including plants, animals, and bacteria. - They are also found in rocks, soil, the atmosphere, and oceans. 3. Describe carbon-oxygen cycle. - Carbon dioxide is taken up by plants during photosynthesis. - The plants use carbon dioxide to make sugar and release oxygen. - Animals breathe in oxygen and breathe out carbon dioxide. - When organisms die, decomposers break down their bodies and release carbon dioxide back into the atmosphere. - Carbon dioxide can also be released into the atmosphere when fossil fuels are burned. - Carbon dioxide dissolves in water and is used by marine organisms to make shells. - Over time, these shells can become part of sedimentary rocks. - When rocks are uplifted, the carbon dioxide is released back into the atmosphere. - The carbon-oxygen cycle is a complex process that is constantly changing. - However, it is essential for life on Earth because it provides the oxygen we breathe and the carbon needed to build organic molecules.