geochemical cycles

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Geochemical Cycles. Water Cycle. Evaporation = water changing from liquid form to gas. Movement of water among ocean, atmosphere, and land. Enters atmosphere through evaporation and transpiration (plant leaves). Transpiration = plant leaves losing water to the atmosphere. - PowerPoint PPT Presentation


  • Geochemical Cycles

  • Water CycleMovement of water among ocean, atmosphere, and land.Enters atmosphere through evaporation and transpiration (plant leaves)Hurricane Katrina approachesEvaporation = water changing from liquid form to gasTranspiration = plant leaves losing water to the atmosphere

  • Geochemical CyclesWater CycleWhen air is warmed up, the particles get farther apart (and so have lower density).H20 rises in columns of warm air and may remain in atmosphere for about 2 weeks.As the H20 vapor rises, it cools into droplets (condenses), forming cloudsCondensation = water vapor transforming into liquid water. Occurs because cooler air does not have as much space to hold water vapor.

  • Water CycleEnters land through precipitation and condensation.Enters lakes or rivers through runoffEnters groundwater where it enters the biosphere.When water vapor in the air cools (usually at night), it condenses on grass (dew) or in the air (fog).Runoff = any water moving across the landGroundwater = any water stored underground!

  • WATER CYCLEOCEANSLAKESMountainsStreamsSUNRun OffAquiferGroundwaterMovement of water vapor by windPrecipitationEvaporationPrecip and CondenEvaporation & Transpiration

  • Humans affect the water cycleHigher global temperature increased evaporation.Higher ocean temps increase evaporationReduction in rainforest reduces transpiration.Reduction of plant life increases runoffGlacial melting reduces amount of reflected light

  • Geochemical CyclesCarbon CycleEarly atmosphere of Earth 95% CO2. Photosynthetic plants removed some of the CO2 and added O2. Todays atmosphere is 0.04% CO2!Reactions of photosynthesis and cellular respiration couldnt take place without carbon. These two reactions form a continuous cycle.Two important sources of Carbon are the ocean (since CO2 dissolves easily in H20) and rocks (such as coal, ore and limestone formed from dead organisms)Carbon is found in the atmosphere primarily as CO2Photosynthesis: Plants taking CO2 out of the atmosphere and using it to produce sugar.Cellular Respiration: Organisms take that sugar and in the process of burning energy release CO2 back into the atmosphere.

  • And, another way to look at the carbon cycle:

  • Humans affect the Carbon CycleBurning of fossil fuels, (oil, coal and natural gas). Fossil fuels were formed very long ago and is fixed: essentially locked out of the carbon cycle. By burning fossil fuels the carbon is released back into the cycle.

  • Humans affect the Carbon CycleWe presently release more carbon into the air than can be reabsorbed by photosynthetic organisms, thereby we have a net INCREASE of carbon in the cycle. This atmospheric carbon has a role to play in the warming of the atmosphere.

  • Geochemical CyclesNitrogen CycleOrganisms require Nitrogen to form amino acids for the building of proteins.Lots of N2 in our atmosphere Unfortunately, most organisms CANNOT use atmospheric nitrogen.Nitrogen-fixing bacteria CAN use N2 from the atmosphere. Nitrogen-fixing bacteria convert atmospheric N2 into ammonia (NH4) which is a form of nitrogen that plants CAN use.

  • Nitrogen Cycle Continued Nitrogen-fixing bacteria live in the soil and in roots of legumes. These bacteria also form nitrites (NO2) and nitrates (NO3); which are compounds containing N and O.Nitrate is the most common source of N for plants.Animals get N from the proteins they eat. Decomposers return N to the soil in the form of ammonia and the cycle repeats.So, oftentimes, the nitrogen cycle does not require the N to be returned to atmospheric form!

  • Nitrogen Cycle SummaryAll living organisms require nitrogen to form amino acids to build proteins. Proteins are important for locomotion, reproduction, defense, and structure.Nitrogen makes up 78% of atmosphere as N2 Nitrogen-fixing bacteria are very important - N2 needs to be fixed before it can be used by most living things.

  • NITROGEN CYCLEN2CropsFertilizer ProductionLightningLegumeNitrogen-Fixing Bacteria in soil & rootsNitrogenFixationAmmoniaNitratesNitritesDecomposersDenitrification(GAS)

  • Humans affect the Nitrogen CycleFrom the production and use of nitrogen fertilizers to the burning of fossil fuels in automobiles, power plants, and industries, humans impact this cycle.Nitrogen is essential to living organisms and its availability plays a crucial role in the world's ecosystems.Excessive nitrogen additions can pollute ecosystems

  • Humans affect the Nitrogen CycleIncreased global concentrations of nitrous oxide (N2O), a potent greenhouse gas, in the atmosphere Increased concentrations of nitric oxide, (NO) that drive the formation of smog along with N2OLosses of soil nutrients such as calcium and potassium that are essential for long-term soil fertility

  • Humans affect the Nitrogen CycleAcidification of soils and of the waters of streams and lakesGreatly increased transport of nitrogen by rivers into estuaries and coastal waters where it is a major pollutant.

    Water Cycle = movement of water among ocean, atmosphere and land.- Enters atmosphere through evaporation and transpiration (when plant leaves lose water)When air is warmed up, the particles get farther apart (therefore, lower density) and the air rises.

    Water vapor may remain in the atmosphere for 2 weeks.

    The higher the air rises, the cooler it gets eventually it cools down enough to CONDENSE into droplets. It forms droplets because cooler air doesnt have as much space to hold the water vapor so it forces some of it out of gas form and into liquid/solid form.Enters land by precipitation and condensation (when water vapor in the air cools usually at night condenses on grass = dew or in the air = fog)

    Runoff = any water moving across the land (streams, rivers)

    Percolation = water moving through soil/ground enters groundwater (water stored underground) Water cycle model can be drawn in several waysCarbon is found in the atmosphere primarily as carbon dioxide.Plants have had a big impact on the amount of carbon dioxide in the atmosphere 95% to 0.04%!Carbon cycle requires photosynthesis and cellular respirationPhotosynthesis: Plants take carbon dioxide and water and suns energy and convert that into food (sugar) and oxygenCellular respiration: All living things (plants and animals and bacteria) take that food (sugar) and oxygen and (in their cells) convert that to carbon dioxide and oxygen and energySources of carbon oceans and rocksAgain, many ways to draw the carbon cycleNitrogen cycle:Nitrogen is necessary nutrient for living.We have a lot of nitrogen in our atmosphere (the atmosphere is primarily nitrogen) unfortunately, most organisms CANNOT use atmospheric nitrogen.Nitrogen-fixing bacteria CAN use that atmospheric nitrogen and convert it to ammonia which contains a form of nitrogen that plants CAN use.Nitrogen-fixing bacteria continued .Nitrogen-fixing bacteria live in the roots of legumes and sometimes directly in the soil.In addition to forming ammonia, they commonly also convert atmospheric nitrogen into nitrates.Most plants get their nitrogen through these nitrates produced by the nitrogen-fixing bacteria.Animals get nitrogen through plants or other animals.Decomposers return nitrogen back to the soil (where plants can access it again). So, oftentimes the nitrogen cycle does not require the nitrogen to be returned to atmospheric form!Nitrogen Cycle summary:Nitrogen is required by all living organisms.Although nitrogen is very abundant in our atmosphere, almost all organisms cannot directly use atmospheric nitrogen.As a result, nitrogen-fixing bacteria are very important because they can take that atmospheric nitrogen and convert it to a usable form for plants.Again, many ways to draw a nitrogen cycle.


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