Nutrient CyclesWater, Carbon, Phosphorus,
Nitrogen and Sulfur
Water Cycle Collects, purifies and distributes earth’s supply of water
Driven by evaporation (from oceans, lakes, rivers and soil), precipitation (rain, snow, sleet, dew), and transpiration (from surfaces of plants and soil)
Reservoirs (sinks): groundwater/aquifers, ocean, ice and snow (glaciers), lakes and reservoirs
Humans influence cycle by:• Increased surface runoff• Taking too much groundwater out• Water pollution
Carbon Cylce Building block for organic compounds necessary for life
Key component in atmosphere—greenhouse gases and temperature regulation
Driven by photosynthesis and cell respiration
Reservoirs (sinks): atmosphere, plants, animals, fossil fuels, dissolved in ocean, limestone and ocean sediments
Human Impacts (releasing CO2 into atmosphere):• Driving cars• Deforestation• Burning fossil fuels• Burning forests
Nitrogen Cycle Component of proteins, vitamins and nucleic acids
Cannot be absorbed directly by plants and animals (N2)—rely on nitrogen fixing bacteria
Reservoirs (sinks): atmosphere, ocean sediments, soil (ammonia and nitrates), plants and animals
Human Impacts:• Runoff from fertilizers and decomposition (water, soil)• Burning fuel and fertilizers (atmosphere)• Remove from soils with agriculture and irrigation
Phosphorus Cycle Circulates through water and soil, does not
include the atmosphere
Very slow cycle. Component of nucleic acids and ATP/ADP, bones and teeth
Reservoirs (sinks): phosphate salts in rock and ocean sediments; plants and animals
Human Impacts: • Runoff from mining waste, sewage and fertilizer• Erosion of rock
Sulfur Cycle Used to produce proteins
Stored in underground rocks and minerals, and sulfate salts in ocean sediments
Hydrogen sulfide gas released to atmosphere through volcanoes and decomposers
Reservoirs (sinks): atmosphere, plants, animals, rock and soils, ocean sediments
Human Impacts: • release sulfur dioxide through burning of fossil fuels and refining coal• Mining • Acid rain from fossil fuel burning