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Biogeochemical Cycles Mrs. Stewart Honors Biology CLE 3210.3.4 Describe the events which occur during the major biogeochemical cycles. You will know you have mastered this standard when: You can predict how changes in a biogeochemical cycle can affect an ecosystem Objectives: • Analyze the flow of nutrients in each biogeochemical cycle. • Evaluate the impact that humans have on the biogeochemical cycles. Why do we recycle? • Think – Pair - Share What sustains life on Earth? • Solar energy • The cycling of matter, energy & nutrients • Gravity Two Secrets of Survival: Energy Flow and Matter Recycle • An ecosystem survives by a combination of energy flow and matter recycling. MATTER CYCLING IN ECOSYSTEMS • Nutrient Cycles: Global Recycling – Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. – Nutrients - the elements and compounds that organisms need to live, grow, and reproduce. Macromolecule Review • What element does every organic organism contain? Carbon • What are the 5 major elements that create all the macromolecules? Carbon Hydrogen Oxygen Nitrogen Phosphorous Think – Pair – Share • What would happen to these elements if they were only capable of being used once? – Think about every time an organism is created and/or destroyed They would begin disappearing (dwindling in supply) – like fossil fuels Biogeochemical Cycles – These are just illustrations or representations to show how substances move through air, water, soil, rock and living organisms. Decomposition •Decomposers: – ultimately responsible for recycling of chemical nutrients – releasing the nutrients in detritus •This makes nutrients available again to the autotrophs in the ecosystem Recycling • What nutrients get recycled? – – – – – – Carbon Dioxide Oxygen Water Carbon Nitrogen Phosphorous Water Cycle Movement of Water • Three important processes: 1. Evaporation – adds water as vapor to atmosphere (heat) a. Bodies of water, soil, animal bodies, etc. 2. Transpiration – water evaporates from the leaves of plants 3. Precipitation – water released from the atmosphere (temperature, air pressure) a. Rain, snow, sleet, hail or fog Water Cycle Think-pair-share • What human activities effect the water cycle? – What do we do as humans that could have positive or negative effects on this cycle – 2 minutes Effects of Human Activities on Water Cycle • We alter the water cycle by: – – – – Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Polluting surface and underground water. Contributing to climate change. • How do these changes affect the surrounding ecosystems? Objectives: • Analyze the flow of nutrients in each biogeochemical cycle. • Evaluate the impact that humans have on the biogeochemical cycles. Carbon Cycle Photosynthesis vs Cellular Respiration • Photosynthesis absorbs CO2 from the atmosphere/biosp here and releases O2 • Cellular respiration absorbs O2 from the atmosphere/biosp Carbon is found in 5 major places: 1. 2. 3. 4. 5. Living and dead organisms Carbon Dioxide (CO2) in atmosphere Organic matter in the soil Fossil fuels and rock deposits Oceans – dissolved CO2 and shells Do these plants contain Carbon? What happens to the carbon now? Where is the carbon? Think-pair-share • What human activities effect the Carbon-Oxygen cycle? – What do we do as humans that could have positive or negative effects on this cycle – 2 minutes Effects of Human Activities on Carbon Cycle • We alter the carbon cycle by adding excess CO2 to the atmosphere through: – Burning fossil fuels. – Clearing vegetation faster than it is replaced. • How do those changes affect the surrounding ecosystems? Objectives: • Analyze the flow of nutrients in each biogeochemical cycle. • Evaluate the impact that humans have on the biogeochemical cycles. Nitrogen Cycle Nitrogen Uses: • Proteins – Enzymes, skin, muscles, etc. • Nucleic Acids – DNA – RNA Forms of Nitrogen • Nitrogen is found in many forms in the atmosphere / ecosystem – – – – – – N2 = nitrogen gas (79% of atmosphere) N2O = nitrous oxide NH3 = ammonia NH4 = ammonium NO3 = nitrate NO2 = nitrite Nitrogen Fixation • Converting N2 gas to nitrate (only usable form of nitrogen for most plants) • 2 types: – Natural = lightning, fires and bacteria – Human = fossil fuel combustion, fertilizer manufacturing Nitrogen-fixing bacteria • bacteria that transform Nitrogen gas into a usable form (Nitrate) – Live in the soil – May live in the swellings on the roots of some plants (ex. Beans, peas, clover) • These plants provide sugars for the bacteria, and the bacteria provide usable nitrogen. Recycling Nitrogen • Where is Nitrogen found? – Dead organisms (as proteins & nucleic acids) – Urine & dung • Decomposers: break down and release Nitrogen as NH3 (ammonia) Nitrogen Processes • Ammonification – converting NH3 (ammonia) to NH4 (ammonium) • Nitrification – converting NH4 (ammonium) into NO2 (nitrite) or NO3 (nitrates) • Denitrification – anaerobic bacteria break down NO3 (nitrates) and release N2 (nitrogen gas) into the atmosphere Nitrogen Sources: • Plants = Nitrates from the soil – Use to form proteins • Animals = eating plants/organisms and digesting the proteins and nucleic acids • Humans = have doubled the amount of fixed N2 in the atmosphere in the last 100 years. – HOW? Too much of a good thing? • Too much nitrogen in aquatic ecosystems results in: •Eutrophication = excess nutrients stimulate plant growth (algal blooms); when these plants die, decomposers use up the available oxygen during decomposition. Eutrophication Nitrogen Cycle Think-pair-share • What human activities effect the Nitrogen cycle? – What do we do as humans that could have positive or negative effects on this cycle – 2 minutes Effects of Human Activities on the Nitrogen Cycle • We alter the nitrogen cycle by: – Adding gases that contribute to acid rain. – Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. – Contaminating ground water from nitrate ions in inorganic fertilizers. – Releasing nitrogen into the troposphere through deforestation. Effects of Human Activities on the Nitrogen Cycle • Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. How does this affect the surrounding ecosystems? • Acid rain • creation of ground level ozone • groundwater contamination • eutrophication. •Exploring the Nitrogen Cycle Activity Objectives: • Analyze the flow of nutrients in each biogeochemical cycle. • Evaluate the impact that humans have on the biogeochemical cycles. Phosphorus Cycle Overview • Movement of phosphorus from the environment, to organisms, and back to the environment • Slow process • Normally does not occur in atmosphere because phosphorus rarely occurs as a gas Phosphorus Uses: • Essential material for animals – Form bones, teeth, molecules (DNA/RNA) Where do organisms get phosphorus? • Plants = absorb from soil and water • Animals = eating plants & other organisms Cycle • Rocks erode, and small amounts of phosphorus dissolve as phosphate PO4 3-, in soil and water • Excreted in wastes from organisms • Released by decomposers from dead organisms • Plants absorb from soil and water, through roots • Animals eat plants/other organisms • Some in fertilizers and applied to fields/crops • Washes off into streams, groundwater and soil Phosphorus Cycle Think-pair-share • What human activities effect the Phosphorus cycle? – What do we do as humans that could have positive or negative effects on this cycle – 3 minutes Effects of Human Activities on the Phosphorous Cycle • We remove large amounts of phosphate from the earth to make fertilizer. • We reduce phosphorous in tropical soils by clearing forests. • We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers. What determines population size? Environment vs Habitat • Many species can survive in more than one environment. • But each species has its “home” or habitat. – Fish may be able to live in fish tanks, but would rather live in the wild What do organisms need to survive? • Basic requirements for survival include: – Food – Water – Shelter Competition • An important aspect of the struggle for survival involves competition for limited resources – – – – Food Water Shelter Sunlight Limiting Factors • Limiting factors are factors that affect the population size of a species in a specific environment. • They can be abiotic or biotic. Predator – Prey relationship • Predators are a biotic limiting factor. • They control population size by feeding on prey. • There is a delicate balance that needs to be maintained. Carrying Capacity • When all the limiting factors are considered together we can determine the maximum number of organisms that can survive in an area. How do we determine the Carrying Capacity of a Species? • All limiting factors must be taken into consideration. • It is very difficult to determine the actual carrying capacity. The Lesson of the Kaibab Deer • Purpose: – to graph data on the Kaibab deer population of Arizona from 1905~1939 – to analyze the methods responsible for the changes in the deer population – to propose a management plan for the Kaibab deer population How Many Bears?? Kaibab Forest: North Rim of the Grand Canyon Key Idea • All organisms have the ability to produce populations of unlimited size • But their environment keeps their numbers in check. • THINK-PAIR-SHARE – How? – List examples of limiting factors. – 3 minutes