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) Water Cycle = movement of water among ocean, atmosphere and land. - Enters atmosphere through evaporation and transpiration (when plant leaves lose water) Transpiration = plant leaves losing water to the atmosphere Hurricane Katrina approaches

Geochemical Cycles Water Cycle When 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 clouds 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 doesn’t have as much space to hold the water vapor so it forces some of it out of gas form and into liquid/solid form. Condensation = water vapor transforming into liquid water. Occurs because cooler air does not have as much space to hold water vapor.

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

Movement of water vapor by wind SUN WATER CYCLE Precipitation Precip and Conden Movement of water vapor by wind Mountains Evaporation & Transpiration Run Off LAKES Streams Water cycle – model can be drawn in several ways Evaporation OCEANS Aquifer Groundwater

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

Carbon is found in the atmosphere primarily as CO2 Geochemical Cycles Carbon Cycle Early atmosphere of Earth 95% CO2. Photosynthetic plants removed some of the CO2 and added O2. Today’s atmosphere is 0.04% CO2! 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 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 CO2 Carbon 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 respiration Photosynthesis: Plants take carbon dioxide and water and sun’s energy and convert that into food (sugar) and oxygen Cellular 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 energy Sources of carbon – oceans and rocks Photosynthesis: 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.

Burning of fossil fuels CARBON CYCLE Volcanoes Burning of fossil fuels Photosynthesis Respiration CO2 in the ATMOSPHERE CO2 dissolved in the OCEAN FOSSIL FUELS Used by man Created over time Land Biomass Aquatic Biomass Oil, Natural Gas, Coal… Limestone Dolomite Plants Animals Again, many ways to draw the carbon cycle

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.

Humans affect the Carbon 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.

Geochemical Cycles Nitrogen Cycle Organisms 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 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 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-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 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 N2 Nitrogen-fixing bacteria are very important - N2 needs to be “fixed” before it can be used by most living things. 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.

Nitrogen-Fixing Bacteria in NITROGEN CYCLE N2 Fertilizer Production Lightning Denitrification (GAS) Nitrogen Fixation Crops Sheep Legume Again, many ways to draw a nitrogen cycle. Nitrogen-Fixing Bacteria in soil & roots Decomposers Ammonia Nitrates Nitrites

Humans affect the Nitrogen Cycle 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 (N2O), a potent greenhouse gas, in the atmosphere Increased concentrations of nitric oxide, (NO) that drive the formation of smog along with N2O 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.