Chapter 3Chapter 3

Nutrient CyclesNutrient Cycles

MATTER CYCLING IN MATTER CYCLING IN ECOSYSTEMSECOSYSTEMS

Nutrient Cycles: Global RecyclingNutrient Cycles: Global Recycling Global Cycles recycle nutrients through the Global Cycles recycle nutrients through the

earthearth’’s air, land, water, and living organisms.s air, land, water, and living organisms. Nutrients are the elements and compounds that Nutrients are the elements and compounds that

organisms need to live, grow, and reproduce.organisms need to live, grow, and reproduce. Biogeochemical cycles move these substances Biogeochemical cycles move these substances

through air, water, soil, rock and living organisms.through air, water, soil, rock and living organisms.

WaterWater’’ Unique Properties Unique Properties There are strong forces of attraction between There are strong forces of attraction between

molecules of water.molecules of water. Water exists as a liquid over a wide Water exists as a liquid over a wide

temperature range. temperature range. Liquid water changes temperature slowly.Liquid water changes temperature slowly. It takes a large amount of energy for water to It takes a large amount of energy for water to

evaporate.evaporate. Liquid water can dissolve a variety of Liquid water can dissolve a variety of

compounds.compounds. Water expands when it freezes.Water expands when it freezes.

The Water CycleThe Water Cycle

Figure 3-26Figure 3-26

Effects of Human Activities Effects of Human Activities on Water Cycleon Water Cycle

We alter the water cycle by:We alter the water cycle by: Withdrawing large amounts of freshwater.Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils.Clearing vegetation and eroding soils. Polluting surface and underground water.Polluting surface and underground water. Contributing to climate change.Contributing to climate change.

The Carbon Cycle:The Carbon Cycle:Part of NaturePart of Nature’’s Thermostats Thermostat

Figure 3-27Figure 3-27

Effects of Human Activities Effects of Human Activities on Carbon Cycleon Carbon Cycle

We alter the We alter the carbon cycle by carbon cycle by adding excess COadding excess CO22 to the atmosphere to the atmosphere through:through: Burning fossil fuels.Burning fossil fuels. Clearing vegetation Clearing vegetation

faster than it is faster than it is replaced.replaced.

Figure 3-28Figure 3-28

The Nitrogen Cycle: The Nitrogen Cycle: Bacteria in ActionBacteria in Action

Figure 3-29Figure 3-29

Nitrogen Cycling TerminologyNitrogen Cycling Terminology

Fixing Nitrogen- converting nitrogen gasFixing Nitrogen- converting nitrogen gas

into forms that can be used by plantsinto forms that can be used by plants

*electrical discharge*electrical discharge

*nitrogen fixing bacteria*nitrogen fixing bacteria

Nitrogen Fixation– soil BacT, produce Nitrogen Fixation– soil BacT, produce ammoniumammonium

Nitrification– soil BacT, produces nitrate Nitrification– soil BacT, produces nitrate

Ammonification- decomposing BacT convert Ammonification- decomposing BacT convert wastes, dead organisms. Produces wastes, dead organisms. Produces ammonia and ammoniumammonia and ammonium

Denitrification-water BacTDenitrification-water BacT

Effects of Human Activities Effects of Human Activities on the Nitrogen Cycleon the Nitrogen Cycle

We alter the nitrogen cycle by:We alter the nitrogen cycle by: Adding gases that contribute to acid rain.Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through Adding nitrous oxide to the atmosphere through

farming practices which can warm the farming practices which can warm the atmosphere and deplete ozone.atmosphere and deplete ozone.

Contaminating ground water from nitrate ions in Contaminating ground water from nitrate ions in inorganic fertilizers.inorganic fertilizers.

Releasing nitrogen into the troposphere through Releasing nitrogen into the troposphere through deforestation.deforestation.

Effects of Human Activities Effects of Human Activities on the Nitrogen Cycleon the Nitrogen Cycle

Human activities Human activities such as such as production of production of fertilizers now fix fertilizers now fix more nitrogen more nitrogen than all natural than all natural sources sources combined.combined.

Figure 3-30Figure 3-30

The Phosphorous CycleThe Phosphorous Cycle

Figure 3-31Figure 3-31

Effects of Human Activities Effects of Human Activities on the Phosphorous Cycleon the Phosphorous Cycle

We remove large amounts of phosphate from We remove large amounts of phosphate from the earth to make fertilizer.the earth to make fertilizer.

We reduce phosphorous in tropical soils by We reduce phosphorous in tropical soils by clearing forests.clearing forests.

We add excess phosphates to aquatic We add excess phosphates to aquatic systems from runoff of animal wastes and systems from runoff of animal wastes and fertilizers.fertilizers.

The Sulfur CycleThe Sulfur Cycle

Figure 3-32Figure 3-32

Effects of Human Activities Effects of Human Activities on the Sulfur Cycleon the Sulfur Cycle

We add sulfur dioxide to the atmosphere by:We add sulfur dioxide to the atmosphere by: Burning coal and oilBurning coal and oil Refining sulfur containing petroleum.Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free Convert sulfur-containing metallic ores into free

metals such as copper, lead, and zinc releasing metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.sulfur dioxide into the environment.