Presentation on theme: "Geochemical Cycles. Water Cycle Movement of water among ocean, atmosphere, and land. Enters atmosphere through evaporation and transpiration (plant."— Presentation transcript:
Water Cycle Movement of water among ocean, atmosphere, and land. Enters atmosphere through evaporation and transpiration (plant leaves) Hurricane Katrina approaches Evaporation = water changing from liquid form to gas Transpiration = plant leaves losing water to the atmosphere
Geochemical Cycles Water Cycle When air is warmed up, the particles get farther apart (and so have lower density). H 2 0 rises in columns of warm air and may remain in atmosphere for about 2 weeks. As the H 2 0 vapor rises, it cools into droplets (condenses), forming clouds Condensation = water vapor transforming into liquid water. Occurs because cooler air does not have as much space to hold water vapor.
Water Cycle Enters land through precipitation and condensation. Enters lakes or rivers through runoff Enters 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 land Groundwater = any water stored underground!
WATER CYCLE OCEANS LAKES Mountains Streams SU N Run Off Aquifer Groundwater Movement of water vapor by wind Precipitation Evaporation Precip and Conden Evaporation & Transpiration
Humans affect the water cycle Higher global temperature increased evaporation. Higher ocean temps increase evaporation Reduction in rainforest reduces transpiration. Reduction of plant life increases runoff Glacial melting reduces amount of reflected light
Geochemical Cycles Carbon Cycle Early atmosphere of Earth 95% CO 2. Photosynthetic plants removed some of the CO 2 and added O 2. Today’s atmosphere is 0.04% CO 2 ! Reactions of photosynthesis and cellular respiration couldn’t take place without carbon. These two reactions form a continuous cycle. Two important sources of Carbon are the ocean (since CO 2 dissolves easily in H 2 0) and rocks (such as coal, ore and limestone formed from dead organisms) Carbon is found in the atmosphere primarily as CO 2 Photosynthesis : Plants taking CO 2 out of the atmosphere and using it to produce sugar. Cellular Respiration : Organisms take that sugar and in the process of burning energy release CO 2 back into the atmosphere.
CARBON CYCLE Volcanoes Burning of fossil fuels Photosynthesis Respiration CO 2 in the ATMOSPHERE CO 2 dissolved in the OCEAN FOSSIL FUELS Photosynthesis Used by man Created over time Land Biomass Aquatic Biomass Oil, Natural Gas, Coal… Limestone Dolomite Plant s Respiration Animals Plants Animals
And, another way to look at the carbon cycle:
Humans affect the Carbon Cycle Burning 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.
We 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. Humans affect the Carbon Cycle
Geochemical Cycles Nitrogen Cycle Organisms require Nitrogen to form amino acids for the building of proteins. Lots of N 2 in our atmosphere Unfortunately, most organisms CANNOT use atmospheric nitrogen. Nitrogen-fixing bacteria CAN use N 2 from the atmosphere. Nitrogen-fixing bacteria convert atmospheric N 2 into ammonia (NH 4 ) 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 (NO 2 ) and nitrates (NO 3 ); 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 Summary All 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 N 2 Nitrogen-fixing bacteria are very important - N 2 needs to be “fixed” before it can be used by most living things.
From 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 Cycle
Increased global concentrations of nitrous oxide (N 2 O), a potent greenhouse gas, in the atmosphere Increased concentrations of nitric oxide, (NO) that drive the formation of smog along with N 2 O Losses of soil nutrients such as calcium and potassium that are essential for long-term soil fertility Humans affect the Nitrogen Cycle
Acidification of soils and of the waters of streams and lakes Greatly increased transport of nitrogen by rivers into estuaries and coastal waters where it is a major pollutant. Humans affect the Nitrogen Cycle