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BIOGEOCHEMICAL CYCLES Ecology UNIT What is a Biogeochemical cycle? ORGANISMS matter matter ENVIRONMENT FOUR MAJOR CYCLES CARBON NITROGEN PHOSPHORUS WATER Importance to Organisms Carbon Organic compounds Nitrogen Proteins & nucleic acids Phosphorus Water ATP, Nucleic acids Water !! The Carbon Cycle In nature: CO2 gas in atmosphere CO32- dissolved in oceans HCO3- dissolved in oceans limestone rocks fossil fuels (coal, oil, CH4) cellulose In organisms: plants/algae/cyanobacteria: Photosynthesis (C-fixing) animals: consumption of plants and/or primary consumers Return to Environment: cellular respiration combustion of fossil fuels decomposition of organic material The Nitrogen Cycle In nature: N2 gas in atmosphere NH4+ in soil NH3 and N-containing waste nitrite (NO2-), nitrate (NO3-) In organisms: plants: absorption of NH4+ or nitrate in soil animals: consumption of plants and/or primary consumers How do plants absorb Nitrogen? Nitrogen Fixation Nitrification Assimilation Nitrogen Fixation Bacteria in soil and plant nodules N2 gas nitrogenase or lightning or UV radiation N+H Nitrification Ammonium Ammonia Nitrite soil bacteria Nitrate Assimilation Plant roots absorb nitrate or ammonia formed by previous processes. Nitrogen is incorporated into plant proteins / nucleic acids. Return to Environment: Bacterial action: NO3N2 to atmosphere + Organic cmpds NH4 (decomposition / ammonification) Animal Action: Excretion of NH4+ / NH3 in urea or uric acid. The Phosphorus Cycle In nature: no gaseous state :. Non atmospheric stored in rocks: Erosion P in soil P in water In organisms: plants: root absorption from soil animals: consumption of plants and/or primary consumers Return to the Environment: Decomposers Excretion of P by animals The Phosphorus Cycle The Water Cycle In nature: oceans air (vapor) groundwater glaciers In organisms: plants: absorption from soil animals: drinking eating plants / other animals Return to Environment: Transpiration in plants Animal / Plant Decomposition What distinguishes the Water Cycle from the others??
