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

Water 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 by this 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 the atmosphere? 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 CO 2 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

20 Nitrogen cycle N 2 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 (NO 3 -1 ) & ammonium ion (NH 4 + ) 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

21 Variations in Cycling RATES Depends on: 1) Biotic factors soil warmth & moisture, diverse number of decomposers 2) Abiotic factors external temperature & O 2 level also, soil chemistry& frequency of fires tropical forests = few months cooler forest = 4-6 years tundra = up to 50 years