living in the environment 17 th miller/spoolman chapter 3 -part 2- biogeochemical cycles
TRANSCRIPT
3-4 What Happens to Matter in an Ecosystem?
• Concept 3-4 Matter, in the form of nutrients, cycles within and among ecosystems and the biosphere, and human activities are altering these chemical cycles.
Nutrients Cycle in the Biosphere
• Biogeochemical cycles, nutrient cycles• Hydrologic• Carbon• Nitrogen• Phosphorus• Sulfur
• Nutrients may remain in a reservoir for a period of time
Water Cycles through the Biosphere• Natural renewal of water quality: three major processes
• Evaporation• Precipitation• Transpiration
• Alteration of the hydrologic cycle by humans• Withdrawal of large amounts of freshwater at rates faster than
nature can replace it• Clearing vegetation• Increased flooding when wetlands are drained
Fig. 3-16, p. 67
Condensation Condensation
Ice and snow
Transpiration from plants
Precipitation to land Evaporation of
surface water Evaporation from ocean
Runoff
Lakes and reservoirs Precipitatio
n to oceanRunoff
Increased runoff on land covered with crops, buildings and pavementInfiltration and
percolation into aquifer
Increased runoff from cutting forests and filling wetlands
Runoff
Groundwater in aquifers
Overpumping of aquifers
RunoffWater pollution
Ocean
Natural process
Natural reservoir
Human impacts
Natural pathwayPathway affected by human activities
Science Focus: Water’s Unique Properties
• Properties of water due to hydrogen bonds between water molecules:• Exists as a liquid over a large range of temperature• Changes temperature slowly• High boiling point: 100˚C• Adhesion and cohesion• Expands as it freezes • Solvent• Filters out harmful UV
Carbon Cycle Depends on Photosynthesis and Respiration
• Link between photosynthesis in producers and respiration in producers, consumers, and decomposers
• Additional CO2 added to the atmosphere• Tree clearing• Burning of fossil fuels• Warms the atmosphere
Fig. 3-19, p. 70
Carbon dioxide in atmosphere Respiration
Photosynthesis
Animals (consumers) Burning
fossil fuelsDiffusion Forest fires
Plants (producers)Deforestation
Transportation RespirationCarbon in
plants (producers)
Carbon dioxide dissolved in ocean
Carbon in animals
(consumers)Decomposition
Marine food webs Producers, consumers, decomposers
Carbon in fossil fuels
Carbon in limestone or dolomite sediments
Compaction
Process
Reservoir
Pathway affected by humans
Natural pathway
Nitrogen Cycles through the Biosphere: Bacteria in Action (1)
• Nitrogen fixed by lightning• Nitrogen fixed by bacteria and cyanobacteria• Combine gaseous nitrogen with hydrogen to make
ammonia (NH3) and ammonium ions (NH4+)
• Nitrification • Soil bacteria change ammonia and ammonium ions to
nitrate ions (NO3-)
• Denitrification• Nitrate ions back to nitrogen gas
Nitrogen Cycles through the Biosphere: Bacteria in Action (2)
• Human intervention in the nitrogen cycle1. Additional NO and N2O in atmosphere from burning
fossil fuels; also causes acid rain2. N2O to atmosphere from bacteria acting on
fertilizers and manure3. Destruction of forest, grasslands, and wetlands4. Add excess nitrates to bodies of water5. Remove nitrogen from topsoil
Fig. 3-20, p. 71
ProcessNitrogen in atmosphere
Denitrification by bacteriaReservoirNitrification by bacteriaPathway affected by humans
Natural pathwayNitrogen in
animals (consumers)Nitrogen oxides
from burning fuel and using inorganic fertilizers
Volcanic activity
Electrical storms
Nitrogen in plants
(producers)
DecompositionNitrates from
fertilizer runoff and
decompositionUptake by plants
Nitrate in soil
Nitrogen loss to deep ocean sediments
Nitrogen in ocean sediments
Bacteria
Ammonia in soil
Phosphorus Cycles through the Biosphere
• Cycles through water, the earth’s crust, and living organisms
• Limiting factor for plant growth
• Impact of human activities1. Clearing forests2. Removing large amounts of phosphate from the
earth to make fertilizers3. Erosion leaches phosphates into streams
Fig. 3-21, p. 73
ProcessReservoir
Pathway affected by humansNatural pathway
Phosphates in sewage
Phosphates in fertilizer Plate
tectonicsPhosphates in mining waste RunoffRunoff
Sea birds
RunoffPhosphate in rock (fossil bones, guano)
ErosionOcean food webs
Animals (consumers) Phosphate
dissolved in water
Phosphate in shallow ocean sediments
Phosphate in deep ocean sediments
Plants (producers)
Bacteria
Sulfur Cycles through the Biosphere• Sulfur found in organisms, ocean sediments, soil, rocks, and
fossil fuels
• SO2 in the atmosphere
• H2SO4 and SO4-
• Human activities affect the sulfur cycle• Burn sulfur-containing coal and oil• Refine sulfur-containing petroleum• Convert sulfur-containing metallic mineral ores
Fig. 3-22, p. 74
Sulfur dioxide in atmosphere
Sulfuric acid and Sulfate deposited as acid rain
Smelting Burning coal
Refining fossil fuels
Dimethyl sulfide a bacteria byproduct
Sulfur in animals
(consumers)
Sulfur in plants
(producers)Mining and extraction Uptake
by plantsSulfur in ocean sediments
Decay
Decay
Process Sulfur in soil, rock
and fossil fuelsReservoirPathway affected by humansNatural pathway