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Nutrient Cycles & how Humans impact nutrient cycling

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Presentation on theme: "Nutrient Cycles & how Humans impact nutrient cycling"— Presentation transcript:

1 Nutrient Cycles & how Humans impact nutrient cycling

2 Where do energy & nutrients come from?
What are nutrients? What else do organisms need to survive and grow? Organisms need _______, ______, and a number of key elements like _______, _______, ________, and _________. How do organisms get all of the above? Energy water carbon oxygen nitrogen hydrogen

3 Energy Flows, Nutrients Cycle
Energy enters the biosphere continually from _________. However, all the water and matter (the stuff) organisms need to survive already exists in the biosphere -- it simply gets ______ over and over. If the water & matter we need to live wasn’t ________, we would eventually run out. We have no other source of these things entering the biosphere. So the recycling of matter is very important. How does matter get recycled? A variety of ways… the SUN reused recycled

4 The Water Cycle Atmospheric water vapor (13) condensation condensation Water content of oceans (1,380,000) Water content of sedimentary rocks near earth’s surface (210,000) #’s in parentheses indicate amount of water as billion billion (1018) grams/yr

5 Water Cycles Through the Biosphere…
1a: Liquid water in rivers, lakes & oceans evaporates as it turns into water vapor (gas). 1b: Water vapor is also released from plants during transpiration. 2: Water vapor in atmosphere condenses to form clouds (liquid again). 3: Water returns to earth during precipitation. 4: Precipitation over land may runoff into bodies of water or infiltrate the soil and percolate into the ground to become groundwater (which is stored in aquifers). 5: Water in ground is absorbed by plants through roots. Surface water & groundwater flows to ocean. Now go back to the beginning…

6 Water Cycle is Affected by Human Action
Clearing vegetation from land for agriculture, mining, road & building construction often increases runoff and can reduce infiltration that recharges underground water supplies Use of groundwater for irrigation increases evaporation over land and depletes groundwater supplies (aquifer depletion). Ex) Ogallala aquifer (world’s largest known aquifer) Found under parts of WY, SD, NE, KA, CO, OK, NM, TX Used to irrigate vast areas of arid high-plains prairie into one of largest, most-productive agricultural regions in US (produces 1/5 of US agricultural output) In some areas, water is being pumped out 8-10 times faster than the (slow) natural recharge rate

7 Ogallala Aquifer

8 Dead Plants and Animals
Carbon Cycle Decomposers (bacteria in soil & others) Dead Plants and Animals

9 Carbon: From Air to Organism
Carbon dioxide (CO2) in air is used by ______ during _____________. Carbon moves from CO2 in atmosphere into sugars in plants. plants photosynthesis CO2 + H2O + sunlight --> C6H12O6 + O2

10 Carbon: From Organism to Air
Organic compounds (like C6H12O6) in plants, animals and microbes are used (“burned”) as an energy source. This process, which organisms carry out to release energy from their food, is called __________________. As part of this process, waste ____ is released. cellular respiration C6H12O6 + O2 --> CO2 + H2O + ATP (chemical energy) CO2

11 Other Ways Carbon Circulates (including Human Impact)
Burning of forests or other organic matter releases CO and CO2 into the atmosphere. Burning of fossil fuels (_____, ___, __________) for industry, transportation, and municipal energy production also releases CO and CO2. Anaerobic bacteria (like those in mammalian digestive systems) produce _____________ (CH4) as a byproduct of their metabolism. coal oil petroleum methane gas

12 Dead Plants and Animals
Carbon Cycle Decomposers (bacteria in soil & others) Dead Plants and Animals

13 Ammonia (NH3) taken in by legumes
Nitrogen Cycle Ammonia (NH3) taken in by legumes Dead Plants & Animals Decomposers Ammonia (NH3)

14 Nitrogen: From Air to Soil
Why do organisms need nitrogen? Molecular nitrogen gas (N2) in atmosphere not directly usable by most organisms 1: ________________ bacteria in legume root nodules and in soil “fix” nitrogen, converting N2 into ammonia (NH3) Nitrogen-fixing Clover root nodules inhabited by Rhizobium bacteria

15 Nitrogen: From Soil to Plant
2: Some ammonia in soil is used directly by plants (absorbed through roots) to make _____________, but many plants still cannot use this form of nitrogen. 3: Most ammonia in soil is converted to nitrite (NO2-) and then nitrate (NO3-) by _________ bacteria. 4: Nitrate (NO3-) is the form of nitrogen that most plants can absorb (through roots) and use to make _____________. plant proteins nitrifying plant proteins

16 Nitrogen: From Plant to Animal to Soil Again!
5: Animals get their nitrogen by ____________________________ . 6: Plants & animals die, are broken down by _____________ bacteria, producing ________________ in the soil again. Guess what can happen to this _____ now? eating plants and other animals decomposing ammonia (NH3) NH3 • can be assimilated (taken in & used) by Plants to make Proteins • can be used by Nitrifying Bacteria & converted to Nitrate

17 Nitrogen: From Soil to Air again
7: __________ bacteria in soil convert nitrites & nitrates to molecular nitrogen gas This is especially true in low O2 conditions Implications for farmers? Denitrifying

18 Other Factors in the Nitrogen Cycle
Nitrogen fixation also occurs in some amount due to lightening strikes Nitrogen compounds also released into atmosphere by volcanoes

19 Nitrogen Cycle Dead Plants & Animals Decomposers Ammonia (NH3)

20 Human Effects on Nitrogen Cycle
Nitrogen oxides emitted from the combustion of fossil fuels (from industry, transportation) Excess nitrogen compounds released into environment via improper disposal of livestock waste/manure (think pig poop) or even untreated human sewage Nitrate and phosphate-rich fertilizers used heavily in agriculture ==> can lead to ______________ (enrichment of a previously limiting nutrient) of freshwater ecosystems due to fertilizer-contaminated runoff from farmland. What’s so bad about this? Let’s see… eutrophication

21 Eutrophication as a process:

22 Eutrophication Effects (in pictures)
Also check out:

23 Phosphorus Cycle

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