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Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur
Ecological Cycles Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur
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The Nitrogen cycle
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The Nitrogen Cycle Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids. 78% of the world’s atmosphere is nitrogen Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+ ) and the ion nitrate (NO3- ) and CONNOT use raw atmospheric nitrogen
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Four processes participate in the cycling of nitrogen through the biosphere:
nitrogen fixation atmospheric fixation by lightning biological fixation by certain microbes industrial fixation – making ammonia decay (ammonification) – bacteria convert dead matter and wastes into ammonia nitrification – bacteria convert ammonia into nitrates and nitrites denitrification – bacteria return nitrogen to the atmosphere
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Human Influence on Nitrogen Cycle
artificial nitrogen fertilization planting of nitrogen fixing crops N2O has risen in the atmosphere as a result of agricultural fertilization, biomass burning, cattle and feedlots, and other industrial sources (N2O also destroys ozone) eutrophication
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Water Cycle
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Water Cycle – Man’s Influence
Tropical Rain Forest – deforestation Less trees = less tramsiration = less water in atmosphere = less rain Olalla Reservoir Huge groundwater store in central U.S. Being depleted faster than replenished
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Carbon Cycle
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Carbon Cycle O.03 carbon dioxide in atmosphere
Plants take in CO2 and release O2 in PHOTOSYNTHEIS Animals take in O2 and release CO2 in CELLULAR RESPIRATION Decay also release CO2 into the atmosphere
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Man’s Influence on Carbon Cycle
Burning fossil fuels releases CO2 into atmosphere Cellulose in dead plant material is hard to breakdown (too big) Accumulates undecomposed over time forming peat Peat over time and under pressure forms fossil fuels When fossil fuels are burned – releases carbon
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Sulfur Cycle Sulfur Most sulfur is in rock and mineral slats
Component of proteins Component of vitamins Most sulfur is in rock and mineral slats Released naturally into atmosphere from volcanoes and decomposition in wetlands In atmosphere, SO2 reacts with water to produce sulfuric acid
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Man’s Influence We release excess SO2 into the atmosphere by:
Burning fossil fuels Refining petroleum products Mining processes
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Chemosynthesis Ocean vents in trenches
Bacteria use hydrogen sulfide H2S as energy source
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Phosphorus Cycle Phosphorus important in DNA molecules ATP
Cell membranes Bones Teeth shells
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Slow cycle Not much in atmosphere – but in soil, rock, and water Big water component
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Phosphorus Cycle
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