2.3

Cycling of Matter

Main Idea

• Essential nutrients are cycled through biogeochemical processes.

Cycles in the Biosphere

• A constant supply of usable energy for the biosphere is needed.

• But the law of conservation of mass states “ matter can neither be created nor

destroyed”. • So this matter must be cycled through

natural processes in the biosphere.

Cycles in the Biosphere

• Matter – anything that takes up space and has mass – Provides the nutrients needed for organisms

to function

• Nutrient – a chemical substance that an organism must obtain from its environment to sustain life and to undergo life processes

Cycles in the Biosphere

• The cycling of nutrients in the biosphere involves both matter in living organisms and physical process s found in the environment – Examples: weathering of rocks

• Biogeochemical cycle – the exchange of matter through the biosphere

The Water Cycle

• Living organisms need water to survive • Where can you find water?

The Water Cycle

Water is constantly evaporating into the atmosphere

The Water Cycle

• Water is constantly evaporating into the atmosphere

• Water vapor – water in the atmosphere • Clouds – form when the cooling water

vapor condenses into droplets around dust • Precipitation – rain, sleet, or hail

–  this is water falling from the clouds back to the Earth’s surface

The Water Cycle

• Ground water – water that flows into streams, rivers, lakes and oceans and then evaporates back into the atmosphere

• About 3% of the water in the world is freshwater

Carbon and Oxygen cycles

• Oxygen is another element that is important to many life processes

• Photosynthesis – when green plants and algae use carbon dioxide and water to make carbohydrates and release oxygen back into the air

• Carbon dioxide is recycled when other organisms undergo cellular respiration

Carbon and Oxygen cycles

• Carbon is also released when fossil fuels are burned, thus adding carbon dioxide into the atmosphere

• Carbon and Oxygen are also stored in calcium carbonate deposits in the ocean from the shells of plankton, coral, clams, and oysters

The Nitrogen Cycle

• Nitrogen is an element found in proteins • Plants and animals cannot use nitrogen

directly, they need bacteria to help them. • Nitrogen Fixation – is when a bacteria

converts nitrogen gas into a usable form for plants

• Lightning also changes nitrogen to a usable form

The Nitrogen Cycle

• Nitrogen returns to the soil when an animal urinates or dies

• Denitrification – soil bacteria convert fixed nitrogen back into nitrogen gas that then returns into the atmosphere

Phosphorus Cycle

•  Phosphorus is an element that is essential to the growth and development of organisms

•  Short term cycle – from soil to producers, from producers to consumers, back to the soil

•  Long term cycle – Weathering of rocks that contain phosphorus slowly adds phosphorus back to the cycle

• Organic phosphate moves through the food web and to the rest of the ecosystem.

Nutrient Cycles

Ocean

Land

Organisms

Sediments

End of 2.3

End of Ch. 2