Chapter 2: Energy Flow and Nutrient Cycles Support Life in Ecosystems

Today

Virtual labhttp://www.mhhe.com/biosci/genbio/virtual_labs/BL_03/BL_03.html Diagram page 76 textbook Nutrient cycling (CARBON) Stores 6 main processes C is cycled Anthropogenic effects Workbook pages

A 54-year old sealed

terrarium

(planted in 1960)no fresh

air or water

2.2 Nutrient Cycles in Ecosystems• Earth’s biosphere acts like a sealed terrarium

where nutrients and wastes are recycled

• Carbon, nitrogen and phosphorus cycles move nutrients in and out of terrestrial and aquatic ecosystems

•Where does the water you drink come from?

2.2 Nutrient Cycles in Ecosystems

Human activities can upset the natural balance of nutrient cycles:

- land clearing- agriculture- industry- motorized transportation

Nutrient Cycling

• Nutrients: chemicals that are needed for plant and animal growth and other life processes.

• Are accumulated in atmosphere, oceans, and land masses

• Stores: location of nutrient accumulation

Nutrient Cycling• Nutrient Cycling: movement in and out of stores

• Caused by biotic and abiotic processes

• Cycles are near balance (input = output)

You need to know about C, N, & P cycles

But O and H are also needed for life

Carbon Cycle

Carbon Stores• All living things contain carbon in their cells

How carbon is stored:

1. Short term stores- vegetation on land, in oceans- animals and decaying OM in soil- atmosphere as CO2

- top layers of ocean

Carbon Stores

2. Long-term stores:- intermediate and deep oceans- coal deposits- marine deposits and sedimentary rock

Carbon StoresStore Amount of C /Gigatonnes

Marine sediments and sedimentary rock

68 000 000 to 100 000 000

Oceans (intermediate/deep) 38 000 to 40 000 Coal Deposits 3 000Soil and organic matter 1 500 to 1 600Atmosphere 750Terrestrial Vegetation 540 to 610Oil and Gas Deposits 300

Where is most carbon stored?

Carbon Stores• Sedimentation:– Traps many long-term carbon stores

– Layers of soil/decomposing OM get buried

– turn into rock/coal/oil/gas by SLOW geological processes

Carbon Stores

• Limestone (CaCO3 ) forms from shell deposits on ocean floor

• Long-term carbon storesare aka carbon sinks

Carbon Cycle

Carbon is cycled through ecosystems by:1. Photosynthesis2. Cellular respiration3. Decomposition

#1) Photosynthesischemical reaction in plants and

cyanobacteria where sunlight

(solar energy) is used to make

glucose (chemical energy)

Sun + 6H20 + 6CO2 → C6H12O6 + 6O2

(sun + water + carbon dioxide → sugar + oxygen)

#1) Photosynthesis

• recycles carbon and oxygen through ecosystems

By eating plants, consumers obtain energy and take carbon into their cells.

#2) Cellular Respiration• Opposite of photosynthesis

• chemical reaction in mitochondria of cells where oxygen is used to liberate energy from glucose.

6O2 + C6H12O6 -> 6CO2 + 6H2O + energy

#3) Decomposition• the breaking down of dead organic matter

• Decomposers (bacteria + fungi) convert organic molecules (carbohydrates) back into carbon dioxide.

Today

Nutrient cycling (CARBON) Review 6 main processes C is cycled What are YOU doing? PHosphorUs and Nitrogen (Phun with a P-H!)

You’re the next contestant!• http://www.bcscience10.com/docs/puzzles/section02_1_puzzle/index.html

• One lucky volunteer gets to click the link and be the host while I check WB 24-26

• You have 10 minutes…

Other ways carbon is cycled#4) Ocean processes (CO3

2-) sediments, marine organisms

remember CaCO3! We made some in a lab.

#5) Volcanic eruptions release CO2

#6) CO2 is rapidly released during forest fires (slowly for decomposing trees)

Human activities and the carbon cycle

• Industry, motorized transportation, land clearing• Industrial revolution (160 yrs ago) CO2 levels increased by

30% from increase of fossil fuel burning• Increase in CO2 in the previous 160 000 ya was 1-3%• We release C from long-term stores FAST (coal, oil, gas)

Anthropogenic effects• Burning fossil fuel reintroduces C to the cycle that was removed in a long term store• CO2, a greenhouse gas, is the most common form of carbon

absorbs heat in atm.• Contributes to global climate change

Anthropogenic effects?• Clearing land reduces amount of carbon taken from

atmosphere by plants during photosynthesis

• Farm plants remove CO2, but less than natural vegetation

Agriculture: cows are carbon culprits• Our obsession with

cows is causing almost 10% of global warming emissions http://qz.com/128662/our-obsession-with-cows-is-causing-almost-10-of-global-warming-emissions/#/h/15425,1/

• Cows release methane from digestion (23x stronger than CO2)

• Feed is not environmentally friendly

Breaking down the carbon cycle• http://www.bcscience10.com/media/EP_carbon_cycle.swf

Carbon cycle• http://www.bcscience10.com/protect/flash_u1_carbon_cycle.html

Today

Nutrient cycling (CARBON) Review 6 main processes C is cycled What are YOU doing? PHosphorUs and Nitrogen (Phun with a P-H!) BONUS CHALLENGE… tell me what you learned

about nutrient cycling from THE link that was NOT covered in class (5 marks maximum, handed in at beginning of next class)

www.kssscience.weebly.com