Nutrient Cycles:

How Nature Recycles Matter

Matter in Ecosystems:The Carbon, Nitrogen and

Water Cycles

Matter: Recycled• The atoms and molecules available to make up

organisms on earth is limited

• The total amount of matter is fixed (unchanging)

• All the atoms MUST be recycled in order for new organisms to form.– It is very likely that at least one

of the carbon atoms in your body was also in a 70 million year old dinosaur!

The Water Cycle

The Water CycleWater can be found in the atmosphere, on

land, in the ocean, and even underground.

• It is recycled over and over through the water cycle.

• In the cycle, water changes state

between liquid (water), solid (ice), and gas (water vapor or steam).

- The sun causes water from the oceans, lakes and other areas to heat up and EVAPORATE.

-Most water vapour gets

into the atmosphere bythis process

The Water Cycle

Evaporate

Sun

The Water Cycle

As the water goes into the atmosphere it condenses to form water droplets.

-These droplets form clouds. If they combine with each other they grow larger

Evaporate

Sun

Clouds

-Tiny water droplets form clouds-Once they become too heavy to stay in the air, the water from the clouds falls back to the ground as precipitation (rain or snow)

The Water Cycle

The water returns to the ocean through the ground and rivers picking up materials along the way.

What things would be picked up?

The Water Cycle

Once the water returns to the oceans, rivers or lakes, it is evaporated by the sun to make clouds again.

The Water Cycle

Evaporate

Sun

The Carbon Cycle

• Carbon is the building block of ALL living things

• Carbon is recycled in the carbon cycle through several processes, but mostly through photosynthesis and respiration.

1. Carbon moves from the atmosphere to plants

• It moves in the form of Carbon dioxide.

• Through the process of PHOTOSYNTHESIS, plants use the sun and carbon dioxide to make their own food

2. Carbon moves from plants to animals• Through the food chain, any carbon in

the plants will move to the animals that eat them.

3. Carbon moves from the animals to the ground• When plants and animals die, their bodies decay bringing carbon back into the ground.

4. Carbon moves from the atmosphere to the oceans.

How does carbon get produced in theatmosphere?• Animals and plants undergo CELLULAR

RESPIRATION, where they release carbon dioxide as they exhale

• When humans burn FOSSIL FUELS to power factories, cars and trucks, most of the carbon enters the atmosphere as carbon dioxide

• DECAY of Organisms- decomposers return Carbon left in detritus (decaying matter) back to the soil in a usable form.

Disrupting the Carbon Cycle

• RECALL: Burning fossil fuels (combustion) returns CO2 to the environment

What’s the problem with this?Too many fossil fuels will increase the amount of

carbon in the environment.- Producers won’t be able to use it fast enough- Creates an unbalanced cycle

Also too much carbon dioxide (which absorbs heat)

Increases the green house effect/global warming.

CARBON CYCLE RECAP!

Combustion (CO2 from cars, factories)

CO2 in atmosphere

Respiration- CO2 released

Decomposition – organic carbon decay

Photosynthesis (uses CO2)

FOSSIL FUELS

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Nitrogen cycle• N2 gas composes 79% of atmosphere

• It is Fixed into the soil by bacteria and in the air by lightning– for use in organisms, nitrogen must be bonded to

other elements i.e. “fixed” – E.g. to react in cells and body, N is supplied as the

nitrate ion (NO3-1) & ammonium ion (NH4

+)

• plants use this to make DNA and convert sugars into proteins

• plants are consumed by animals; proteins and DNA (and Nitrogen) become part of the animal’s proteins.

• animals can only obtain nitrogen by eating plants or other animals

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Variations in Cycling RATESDepends on:

1) Biotic factors• soil warmth & moisture, diverse number of

decomposers

2) Abiotic factors

• external temperature & O2 level

• also, soil chemistry& frequency of fires

tropical forests = few monthscooler forest = 4-6 yearstundra = up to 50 years