Biogeochemical CyclesBiogeochemical Cycles

A carbon atom in your body today may have been part of a blade of grass last year, or a dinosaur bone millions of years ago.

Fossilized bones in a Colorado dig.

+What Sustains Life on Earth?

Solar energy, the cycling of matter, and gravity sustain the earth’s life.

+Two Secrets of Survival: Energy Flow and Matter Recycle

An ecosystem survives by a combination of energy flow and matter recycling.

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Did You Know? Organisms require several dozen nutrients, such as nitrogen, phosphorus, and carbon, to survive.

Nutrient Cycling

Matter cycles through the environment.

Matter can be transformed (changed), but cannot be created or destroyed. Example of change: Evaporation

Liquid water to water vapor

LAW OF CONSERVATION OF MATTER:

Matter can not be created or destroyed

Total amount of matter in the universe is constant.

+MATTER CYCLING IN ECOSYSTEMS

Nutrient Cycles: Global RecyclingGlobal Cycles recycle nutrients through the

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

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

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

+The Water Cycle

+Effects of Human Activities on Water Cycle

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

underground water.Contributing to

climate change.

+Carbon Cycle

+The Carbon Cycle

+Effects of Human Activities on Carbon CycleWe alter the carbon cycle

by adding excess CO2 to the atmosphere through: Burning fossil fuels.Clearing vegetation

faster than it is replaced.

+The Phosphorus Cycle

+Effects of Human Activities on the Phosphorous Cycle

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

We reduce phosphorous in tropical soils by clearing forests.

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

+The Phosphorus CycleEutrophication – the introduction of phosphorus

and nitrogen into a body of water that leads to an overgrowth of algae and other producers.

+The Nitrogen Cycle

+Effects of Human Activities on the Nitrogen Cycle

We alter the nitrogen cycle by:Adding gases that contribute to acid rain.

Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone.

Contaminating ground water from nitrate ions in fertilizers.

Releasing nitrogen into the air through deforestation.

+Nitrogen Fixation

Nitrogen Fixation – the conversion of Nitrogen gas into ammonia.Done by bacteria

Live in soil or plant roots

Production of fertilizers now fix more nitrogen than all natural sources combined.