The water cycle describes the continuous movement of water on, above and below the surface

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1 Nitrogen and carbon cycles Water cycle The water cycle describes the continuous movement of water on, above and below the surface It is driven by radiation, convection and advection. It includes solid, liquid and gaseous water. The main processes are evaporation, transpiration, sublimation and precipitation. Precipitation condensed water which falls to the ground as a liquid or a solid Sublimation water changing from ice directly to a gas Condensation water changes from a gas to a liquid Evaporation Water changing from a liquid to a gas Transpiration process by which plants give off water vapour into the atmosphere. 1

2 There are several types of precipitation: 1) Snow 2) Ice Pellets/Sleet 3) Rain 4) Drizzle 5) Hail Radiant energy from the sun warms the Earth s surface This warming causes evaporation, transpiration and sublimation The warm air rises, then cools and condenses forming clouds with moisture. Precipitation from the clouds falls back to the Earth as rain, snow, sleet, etc. Precipitation is put back into Earth s surface (land and water) and the cycle repeats itself. This is a continuous cycle. 2

3 Matter in ecosystems is cycled; that is it gets broken down and reused. We focus on 3 Cycles Carbon Nitrogen Phosphorous Chemicals that are essential for living things in order to survive. Any substance needed by an organism for proper growth, repair, and function. Examples: nitrogen, oxygen, carbon, water, phosphorus, sulphur, hydrogen. Organic if the substance contains atoms of carbon and hydrogen. Examples: glucose, proteins, fat. Inorganic if the substance does not contain atoms of carbon and hydrogen. Examples: carbon dioxide, water, oxygen. Matter is taken up by living things when organisms eat. Then when that organism dies, the matter is rereleased into the environment to be made available to other living organisms. Thus, matter can be taken up by one organism, then put back into the environment, then taken up by another organism, and then rereleased; thus it cycles through the ecosystem. 3

4 Carbon can help form solid minerals (such as limestone) Can be dissolved in water or carried around the world through the atmosphere as carbon dioxide gas (used in photosynthesis) Makes possible the existence of all organic compounds essential to life on earth (sugars, etc) Carbon is found in every ecosystem around the world in large concentrations: in the atmosphere, in the soil, in living things and the oceans. It is the key element for living things. Sources are organic: in living things; or are inorganic: atmospheric CO 2. Carbon gets moved through the carbon cycle by two main processes: Photosynthesis Cellular Respiration These two processes are complimentary as they move carbon back and forth between inorganic and organic sources of carbon. Inorganic carbon is converted into organic carbon. Green plants use the energy from the sun to combine carbon dioxide from the atmosphere and water from the soil. It creates glucose and oxygen. Organic carbon is released back into the environment. Animals use energy from the sugars as energy to move, then release carbon dioxide back into the environment. 4

5 amesandactivities.htm Carbon can be stored in atmosphere, the oceans and the Earth s crust when it is not in organic form. They form compounds that can stay in those sources for a large amount of time. Most often organisms take in organic forms of carbon and can keep them in their bodies, however when they die, the carbon is released due to the process of decomposition. There are however, some ecosystems such as bogs, which store huge amounts of organic carbon in the form of peat. There is very little oxygen in bogs and therefore decomposition is slow. Sometimes these deposits get overtaken by sediment the layers end up trapping the peat (organic carbon) in layers of rock. This turns into fossil fuels. Oil can form in a similar manner at the bottom of oceans and lakes. This can hold the organic carbon out of the carbon cycle for millions of years. Combustion: We burn fossil fuels and release carbon Deforestation: Humans remove trees and they cannot remove carbon dioxide from the atmosphere We burn wood and release more carbon dioxide into the air Humans are releasing organic carbon into the atmosphere faster than it would naturally. Organic carbon is being released into the atmosphere in an inorganic form and the amount of inorganic carbon is increasing in the atmosphere. 5

6 Life depends on the cycling of nitrogen. Nitrogen is used to make proteins, and for the creation of Deoxyribonucleic acid (DNA); the hereditary information found in all living things. Nitrogen makes up 79% of the gasses in the atmosphere, so you would think that it should be easily accessed by living things; however it is an un-reactive molecule and therefore it reacts only under limited conditions. Lightning Bacteria in the Soil Is extremely complex, atmospheric nitrogen is converted to nitrates in a process called nitrogen fixation (two ways: lightning and bacteria in the soil). Energy from lightning causes nitrogen gas in the air to react with oxygen in the air, producing nitrates The nitrates dissolve in rain or surface water and move through the nitrogen cycle into plants and eventually end up in DNA. The DNA gets consumed by higher level organisms and gets broken down and changed into amino acids. The higher level organism then uses those amino acids in higher organisms for DNA and proteins. 6

7 There are species of bacteria that are able to convert atmospheric nitrogen into nitrates. This is one of the largest sources of nitrates for ecosystems. These bacteria live in the roots of legumes (peas, beans, alfalfa, soybeans, clover, etc) and supply the plant with nitrates and the plant supplies the bacteria with glucose. Dead organic material is broken down and nitrates are released into the soil for other organisms to use. Denitrifying bacteria may break down nitrates into nitrates and then back into atmospheric nitrogen. Farmers want to reduce denitrifying bacteria, so they aerate their lawn, killing the bacteria that break down nitrates. We also add pesticides or fertilizers into the environment ultimedia/uploads/ecology/ncycle.swf 7

8 Important for cells, long molecules of DNA and calcium phosphate in bones. Phosphates cycle in short and long cycles In living things: Living things take in phosphorous, when they die it dissolves into water and gets reused by living things. In rocks in the Earth s Crust: Dissolved in water, the phosphorous settles out and is captured back into rocks. Rocks then may be dissolved away by surface runoff and end up back into the surface runoff when it rains. Phosphates are mined and used to fertilize crops Runoff of phosphates into lakes can damage the lake ecosystem (excessive plant growth blocks sunlight, and the lake gets depleted of oxygen due to less sunlight and more decomposers) dia/ch30/phos_anim.html...not working nimations/content/phosphorouscycle.html 8

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