2.2 Nutrient Cycles in Ecosystems

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1 2.2 Nutrient Cycles in Ecosystems are chemicals required for growth and other life processes. Nutrients move through the biosphere in Nutrients often accumulate in areas called Without interference, generally the amount of nutrients flowing into a store equals. can upset the natural balance of nutrient cycles. Land clearing, agriculture, urban expansion, mining, industry and motorized transportation can all increase. in the biosphere can have unexpected consequences. There are five chemical elements required for life. cycle between living things and the atmosphere. cycles in from sedimentary rock. See pages Nutrient Cycles: The Carbon Cycle are a fundamental unit in cells of all living things. Carbon is also an essential part of that sustain life. Carbon can be stored in many different locations. is found in aquatic and terrestrial organisms, and in CO 2 in the atmosphere and top layers of the ocean. is found in middle and lower ocean layers as dissolved CO 2, and in coal, oil and gas deposits in land and ocean sediments. Sedimentation Layers of become buried on land and under the oceans. Slowly,, coal, oil and gas form. Layers of shells also are deposited in sediments on the ocean floor, over long periods of time. See pages Carbon stores are also known as

2 Nutrient Cycles: The Carbon Cycle (continued) Carbon is cycled through ecosystems in a variety of ways. : energy from the sun allows CO 2 and H 2 O to react CO 2 + H 2 O + sunlight C 6 H 12 O 6 + O 2 Carbon in the atmosphere is by plants into carbohydrates. also occurs in : carbohydrates release energy in consumers C 6 H 12 O 6 + O 2 CO 2 + H 2 O + energy The energy released is used for. : decomposers break down large quantities of cellulose is a carbohydrate most other organisms cannot break down CO 2 dissolves in cold, northern waters and sinks Ocean currents flow to the tropics, the water rises and releases CO 2 This process is called - volcanic eruptions can release Forest fires also release Nutrient Cycles: The Carbon Cycle (continued) See page 76

3 Nutrient Cycles: The Carbon Cycle (continued) Many can influence the carbon cycle Since the start of the (160 years ago), CO 2 levels have increased by from the increased burning of fossil fuels. The increase in CO 2 levels in the previous years was 1% - 3% Carbon is being removed from more quickly than it naturally would as we. CO 2 is also a, which traps heat in the atmosphere. Clearing land for reduces plants that can absorb and convert CO 2. does not remove as much CO 2 as natural vegetation does. See page 77 Nutrient Cycles: The Nitrogen Cycle Nitrogen is very important in the structure of. In animals, proteins are vital for. In plants, nitrogen is important for. The largest store of nitrogen is in the atmosphere in the form. Approximately of the Earth s atmosphere is N 2 gas. Nitrogen is also stored in, and as organic matter in. Smaller nitrogen stores are found in. Nitrogen is cycled through processes involving plants See page 78

4 Nutrient Cycles: The Nitrogen Cycle (continued) Nitrogen fixation is the conversion of into Both nitrate and ammonium compounds are. Nitrogen fixation occurs in one of three ways 1. - lightning provides the energy for N 2 gas to react with O 2 gas to form nitrate and ammonium ions. Compounds formed by these ions then enter the soil via precipitation This only provides a small amount of nitrogen fixation nitrogen-fixing bacteria like Rhizobium in the soil convert N 2 gas into ammonium ions These bacteria grow on the root nodules of legumes like peas. The plants provide sugars, while bacteria provide nitrogen ions some species of cyanobacteria also convert N 2 into ammonium during the process of photosynthesis. Nutrient Cycles: The Nitrogen Cycle (continued) Nitrification occurs when. Ammonium is converted into by nitrifying bacteria. Ammonium is converted to, which is then converted to nitrate. Nitrates enter plant roots These nitrogen compounds compose plant proteins. Herbivores then eat plants, and use nitrogen for DNA and protein synthesis. Nitrogen is returned to the atmosphere via. Nitrates are converted N2 is also returned to the atmosphere.see page 80

5 Nutrient Cycles: The Nitrogen Cycle (continued) Excess nitrogen dissolves in water, enters the waterways, and. The nitrogen compounds eventually become trapped in, and will not be released again until the rocks weather. See page 81 Nutrient Cycles: The Nitrogen Cycle (continued) can also affect the nitrogen cycle. Due to human activities, the amount of nitrogen in the ecosystem has in the last 50 years. releases nitrogen oxide (NO) and nitrogen dioxide (NO 2 ). Burning also releases nitrogen compounds that increase in the form of nitric acid (HNO 3 ). often use large amounts of nitrogen-containing fertilizers. Excess nitrogen is washed away, or, into the waterways. This promotes huge growth in aquatic algae = These algal blooms use up all CO 2 and O 2 and block sunlight, killing many aquatic organisms. The algal blooms can also produce that poison animals.

6 Nutrient Cycles: The Phosphorous Cycle Phosphorous is essential for in plants and animals. Phosphorous is a part of the molecule that in living cells. Phosphorous promotes. In animals, phosphorous and calcium are important for Phosphorous is Instead, it is trapped in phosphates (PO 4 3, HPO 4 2, H 2 PO 4 ) found in rocks and in the sediments on the ocean floor. Weathering releases these phosphates from rocks., via acid precipitation or lichens, releases phosphates. where wind, water and freezing release the phosphates. Phosphates are then absorbed by plants, which are then eaten by animals. Weathering doesn t occur until there is, exposing the rock to chemical and physical weathering. See pages Nutrient Cycles: The Phosphorous Cycle (continued) Humans add excess phosphorous to the environment through Extra phosphorous, often along with potassium, then enters the ecosystems faster than methods can replenish the natural stores. Humans can. of forests removes phosphorous from trees, and it then is deposited as. See page 85

7 How Changes in Nutrient Cycles Affect Biodiversity Any significant changes to any of these nutrients ( ) can greatly impact biodiversity. Carbon cycle changes are adding to Slight temperature fluctuations and changes in water levels can Changes influence. Increased levels of can allow certain plant species to out-compete other species, decreasing resources for every species in those food webs. Decreased levels of can inhibit the growth of algal species which are very important producers in many food chains. See pages 86-87