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APES NDHS Name: _____________________ Date: ______________________ Nutrient Cycles and Human Impact Cycling of in Ecosystems KEY PLAYERS – complete cycle Types of Biogeochemical Cycles: – – NUTRIENT RESEVOIRS: WATER CYCLE Reservoirs The oceans contain of the water in the biosphere. is bound as ice, and is in lakes, rivers, and groundwater. A negligible amount is in the atmosphere. Key processes CARBON CYCLE - base of Reservoirs The major reservoirs of carbon include Key processes by plants and phytoplankton atmospheric . CO2 is added to the by of producers and consumers. add CO2 to the atmosphere. NITROGEN CYCLE Nitrogen is a component of Biologically available forms Plants and algae can use Various bacteria can also use Animals can use only of nitrogen ( ) Reservoirs The major reservoir of nitrogen is the atmosphere, which is of lakes, rivers, and oceans. in surface water and groundwater. Nitrogen is stored in . Key processes Nitrogen enters ecosystems primarily through Some nitrogen is fixed by by bacteria decomposes organic nitrogen. In , bacteria convert NH4+ to NO3−. In , bacteria use NO3− for metabolism instead of O2, releasing N2. - important symbiosis: PHOSPHOROUS CYCLE Part of Biologically available forms , plants absorb and use to synthesize organic compounds. Reservoirs of marine origin. Key processes of rocks gradually adds phosphate to soil. and incorporated into organic Absorbed by material. It is returned to soil or water through biomass or of . Decomposition rates largely determine the rates of nutrient cycling. Decomposition takes an average of years in temperate forests, while in a tropical rain forest, most organic material decomposes in a . The difference is largely the result of and more abundant in tropical rain forests. The rate of decomposition increases with actual – wet and warm Human Impact on Ecosystems and the Biosphere The human population moves nutrients from one part of the biosphere to another. Human activity in nutrient cycles. 1) in the form of : - can exhaust the 2) Introduce : - excess in air atmospheric problems ( ) - excess Nitrates in of water ways, , tainted , 3) Excess : – depletes standing 4) Increase – fossil fuels Acid precipitation: The burning of fossil fuels releases that react with water in the atmosphere to produce and return as Acid precipitation is a than a local one. problem, rather Acid precipitation lowers the soil chemistry of terrestrial ecosystems. With decreased pH, soil. and affects the leach from the The resulting nutrient deficiencies affect the and limit their growth. Freshwater ecosystems are very affects species directly Climate Change: Since the Industrial Revolution, the concentration of – Increased is one consequence of increasing CO2 levels. Rising atmospheric CO2 levels may have an impact on Earth’s . When light energy hits the Earth, much of it is off the surface. CO2 and other gases cause the Earth to that would ordinarily escape the atmosphere. This phenomenon is called the . If it were not for this effect, the average air temperature on Earth would be . A number of studies predict that by the end of the 21st century, atmospheric CO2 concentration will have doubled and average global temperature will rise by . If increased temperatures caused the polar ice caps to melt, sea levels would rise by an estimated , flooding coastal areas from current coastlines. A warming trend would also alter geographic distribution of , making major U.S. agricultural areas much drier. Human activities are depleting atmospheric ozone. Life on earth is protected from the damaging affects of ultraviolet radiation (UV) by a layer of , or ozone, that is present in the . Studies suggest that the ozone layer has been gradually “ ” since 1975. The destruction of ozone probably results from the accumulation of —chemicals used in , as propellant in , and for certain manufacturing The breakdown products from these chemicals Subsequent reactions liberate the , allowing it to react with other in a catalytic chain reaction. The result of a reduction in the ozone layer may be increased levels of that reach the surface of the Earth. Some scientists expect increases in , as well as unpredictable 5) Add to environment - Toxins can become concentrated in successive levels of food webs. by organisms and can accumulate in the of animals and become more concentrated in successive Magnification occurs because the Thus, carnivores tend to be the organisms most by toxic compounds in the environment. - Many toxins cannot be by microbes and persist in the environment for . - Other chemicals may be converted to by reaction with other substances or by the metabolism of microbes. Ex: mercury was routinely expelled into rivers and oceans in an . Bacteria in the bottom mud converted it to , an extremely compound that in the tissues of organisms, including humans who fished in contaminated waters.