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Nutrient Cycling
3.3
Energy vs. Matter Energy flows throughout an ecosystem in ONE
direction from the sun to autotrophs to heterotrophs
Matter is recycled
WHY?
Biogeochemical Cycles “Matter can cycle through ecosystems
because organisms don’t USE it, they TRANSFORM it.”
Matter/Nutrient cycled includes: Water Nitrogen Carbon Phosphorous
Water Cycle Processes involved:
Evaporation-water changes from liquid to atmospheric gas
Transpiration- water evaporates OUT of plant leaves
Also, condensation, precipitation, seepage, runoff…
Carbon Cycle Key ingredient of living tissue, found in many
places Found in animal skeletons, rocks, carbon
dioxide, carbohydrates, etc. Processes Involved That Take Up and Release
Carbon: Biological- photosynthesis, respiration,
decomposition Geochemical- erosion, volcanic activity Mixed- burial and decomposition coal and
petroleum Human Activities- mining, cutting and burning
forests, burning fossil fuels
Nitrogen Cycle All organisms require nitrogen to make amino
acids Occurs in many forms: N2 (78% atm gas),
Ammonia (NH3), Nitrate and Nitrite (NO3- and
NO2-) are found in waste products and
fertilizers Processes involved:
Nitrogen Fixation: conversion of nitrogen gas into ammonia by bacteria (occurs in the roots of legumes) also can occur thru lightning
Ammonia can be converted into nitrates and nitrites, which are taken up by plants and enter the food web
Denitrification: bacteria in soil convert nitrates into nitrogen gas
Phosphorous Cycle All organisms require phosphorous to create
DNA and RNA Does not enter atmosphere, not very common Exists inorganic form in land rock and soil
minerals and ocean sediment Processes involved:
Erosion: sediment washes into rivers, streams, and ocean
Absorption: Plants and marine organisms take up the phosphorous and it moves through the food web