2.2 Nutrient Cycles in Ecosystems2.2 Nutrient Cycles in Ecosystems

Nutrient cyclesNutrient cycles – the flow of nutrients – the flow of nutrients ININ and and OUTOUT of the land, ocean, atmosphere and deep of the land, ocean, atmosphere and deep

rock.rock.

The health of our ecosystems depends on the The health of our ecosystems depends on the balance of:balance of:

Carbon, Nitrogen, PhosphorousCarbon, Nitrogen, Phosphorous, Hydrogen , Hydrogen and Oxygenand Oxygen

CC N P N P H H O O

CARBON CYCLECARBON CYCLE

A. Carbon Facts:A. Carbon Facts: CarbonCarbon is found in all living matter. is found in all living matter. Places that carbon is found are called Places that carbon is found are called stores or sinksstores or sinks

Short-term Stores Long-term Stores- living things in water & on land - underground (oil,

gas, - rotting tissue of plants/animals natural gas and

coal)- atmosphere (air) - sedimentary rock - ocean (dissolved in the water) (limestone)

- ocean floor (old shells)

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B. How Carbon Changes Form:B. How Carbon Changes Form:

1. 1. PhotosynthesisPhotosynthesis (in plants, algae and (in plants, algae and cyanobacteria)cyanobacteria)

CCOO22 + H + H22O + O + sunlight sunlight CC66HH1212OO66 + O + O22

2. 2. Cellular respirationCellular respiration (in cells of all living things) (in cells of all living things)

CC66HH1212OO66 + O + O2 2 CCOO22 + H + H22O + O + ENERGYENERGY

(energy is used for growth, repair etc.)(energy is used for growth, repair etc.)

3.3. DecompositionDecomposition (rotting) – done by (rotting) – done by bacteria/fungibacteria/fungi

cellulose cellulose CCOO22

4. : Ocean mixing: moves CO2 around the world

- CO2 sinks in cold ocean waters flows to the warm equator and evaporates into the air.

5.5. Combustion:Combustion: (burning, engines, volcanoes, (burning, engines, volcanoes, forest fires)forest fires)fossil fuels + Ofossil fuels + O22 CO CO22 + H + H22O + ENERGYO + ENERGY(oil, gas, natural gas, coal)(oil, gas, natural gas, coal)

VOLCANIC ERUPTIONSVOLCANIC ERUPTIONS Sometimes COSometimes CO22 is released from is released from

volcanoes!volcanoes!

MAGMA = Molten

sedimentary rock

Lava going into the ocean at Hawaii’s Volcanoes National Park

FOREST FIRESFOREST FIRES COCO22 is rapidly released during forest is rapidly released during forest

firesfires

Human Activities & COHuman Activities & CO22

1. Burning Fossil Fuels1. Burning Fossil Fuels CCOO22 in atmosphere has increased 30% in past 160 in atmosphere has increased 30% in past 160

years.years. In the 160,000 years before that, it only increased In the 160,000 years before that, it only increased

1-3%.1-3%. CarbonCarbon is removed from long-term storage as we is removed from long-term storage as we

mine coal & drill for oil and gas.mine coal & drill for oil and gas. CCOO22 is also a is also a greenhouse gasgreenhouse gas, (traps heat in , (traps heat in

atmosphere)atmosphere)

2. Removing Trees2. Removing Trees Trees absorb Trees absorb CCOO22, so when they are cut down, , so when they are cut down, CCOO22

is released into the air.is released into the air. Other crops don’t remove as much Other crops don’t remove as much CCOO22

COCO22 on the rise in the on the rise in the atmosphereatmosphere

•For the past 160 000 years, the increase in CO2 was 1-3 %

•Since 1850, the increase has been 30%

Scientists estimate that carbon stores in the atmosphere will

rise by at least 1/3 by the end of the

century.

Burning Fossil Fuels (oil, Burning Fossil Fuels (oil, gas, coal)gas, coal)

HUMAN ACTIVITIES – adding COHUMAN ACTIVITIES – adding CO22 to to atmosphereatmosphere

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Nitrogen CycleNitrogen Cycle

A. Nitrogen FactsA. Nitrogen Facts Makes up Makes up DNA & proteinsDNA & proteins

(muscle function).(muscle function). Help plants grow. Help plants grow.

Nitrogen Stores:Nitrogen Stores: Atmosphere (78% is Atmosphere (78% is NN22)) OceansOceans Organic matter in soilOrganic matter in soil Lakes, marshes, organismsLakes, marshes, organisms

B. How Nitrogen Changes Form:B. How Nitrogen Changes Form:

- - NN22 is not usable by plants or animals, so it has to is not usable by plants or animals, so it has to be converted to other forms.be converted to other forms.

- Plants can use Plants can use NONO33-- (nitrate) (nitrate) and and NHNH44

++ (ammonium)(ammonium)

1.1. Nitrogen FixationNitrogen Fixation Lightning changes Lightning changes NN22 (nitrogen gas) (nitrogen gas) NO NO33

-- (nitrate). (nitrate). Rain washes Rain washes nitratenitrate into soil. (small amount) into soil. (small amount)

Bacteria in soil (Bacteria in soil (rhizobiumrhizobium) & cyanobacteria in ) & cyanobacteria in waterwater

change change NN22 (nitrogen gas) (nitrogen gas) NHNH44+ + (ammonium). (ammonium).

(more)(more)

Lightning provides the energy for nitrogen to react

with oxygen in the atmosphere!

Nitrogen-fixing Nitrogen-fixing bacteriabacteria in the soil in the soil can convert (“fix”) can convert (“fix”) NN22 to ammonium. to ammonium.

Usually live on roots of Usually live on roots of legumeslegumes

and other plants. and other plants.

Rhizobium

Nitrogen-fixing cyanobacteria in water can also

do this!In the waterIn the soil

Video

2.2. Nitrification Nitrification (done by nitrifying (done by nitrifying bacteria).bacteria).

NHNH44+ + (ammonium) (ammonium) NONO22

- - (nitrite) (nitrite) NONO33

- - (nitrate)(nitrate)

3.3. UptakeUptakeNONO33

-- is sucked into plants & used for is sucked into plants & used for growth.growth.Herbivores eat plants & use Herbivores eat plants & use NN for making for making proteins & proteins & DNA.DNA.

4.4. Denitrification Denitrification (done by denitrifying bacteria & volcanic

eruptions) NONO33

- - NN22

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Nitrogen CycleNitrogen Cycle

C.C. Human activities affect the nitrogen cycle.Human activities affect the nitrogen cycle.The amount of nitrogen in the ecosystem has doubled in 50 y. due to:

1.1. Burning fossil fuelsBurning fossil fuels & sewage treatment. & sewage treatment. NONO & & NONO22 are byproducts are byproducts

2.2. Land-clearingLand-clearing by burning. by burning. acid rain is formed which contains acid rain is formed which contains

nitric acid (HNOnitric acid (HNO33).).

3.3. Overfertilization Overfertilization NHNH44

++ & & NONO33-- leach into soil & waterways. leach into soil & waterways.

huge growth in aquatic algae = huge growth in aquatic algae = eutrophicationeutrophication

These These algal bloomsalgal blooms use up all use up all COCO22 & O & O22, block , block sunlight & produce neurotoxins which poison sunlight & produce neurotoxins which poison and kill many aquatic organisms.and kill many aquatic organisms.

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The Phosphorous CycleThe Phosphorous CycleA. PhosphorousA. Phosphorous Facts Facts

Phosphorous is a part of the molecule that carries Phosphorous is a part of the molecule that carries energy in cells (ATP).energy in cells (ATP).

Phosphorous helps root growth, stem strength and Phosphorous helps root growth, stem strength and seed production.seed production.

In animals, phosphorous is important for strong In animals, phosphorous is important for strong bones.bones.

Phosphorus Stores:Phosphorus Stores: Not in atmosphere, but in Not in atmosphere, but in phosphate rocks (POphosphate rocks (PO44

3–3–, , HPOHPO44

2–2–, H, H22POPO44)) and sediments on the ocean floor. and sediments on the ocean floor.

B.B. How How PhosphorousPhosphorous Changes Form. Changes Form.

1.1. WeatheringWeathering (breaking down rock into smaller pieces).(breaking down rock into smaller pieces).

a) Chemical weathering:a) Chemical weathering:

acid rain or lichens releases acid rain or lichens releases phosphates phosphates (PO(PO44

3-3- ) )

b) Physical weatheringb) Physical weathering

wind, water and freezing release the wind, water and freezing release the phosphates.phosphates.

2.2. Uptake: Uptake: plants suck up plants suck up POPO443-3-, then are eaten by , then are eaten by

animals.animals.

3.3. Decomposition:Decomposition: Bacteria break down organic Bacteria break down organic matter & matter &

phosphorous is returned to soil.phosphorous is returned to soil.

4.4. Geologic Uplift:Geologic Uplift: when rocks under the ground when rocks under the ground are pushed up are pushed up mountains mountains weathering. weathering.

Mt. Everest is made of

limestone that must have

originally formed on ancient sea

floor. It contains fossils of marine

creatures. creatures.

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The Phosphorous CycleThe Phosphorous Cycle

C. Human activities affect the Phosphorous C. Human activities affect the Phosphorous Cycle.Cycle.

1. Mining: increases 1. Mining: increases PP in ecosystems quickly. in ecosystems quickly.

2. Slash-and-burn forest practices: turns 2. Slash-and-burn forest practices: turns PP into ash, which into ash, which

runs into waterways.runs into waterways.

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How Changes in Nutrient Cycles How Changes in Nutrient Cycles Affect BiodiversityAffect Biodiversity

Any significant changes to any of these Any significant changes to any of these nutrients (nutrients (CC, H, O, , H, O, NN or or PP) can greatly impact ) can greatly impact biodiversitybiodiversity..

1.1. Carbon cycleCarbon cycle changes changes climate change & climate change & global warming.global warming.

2.2. Too much Too much nitrogennitrogen can allow certain plant can allow certain plant species to out-compete other species.species to out-compete other species.

3.3. Decreased levels of Decreased levels of phosphorousphosphorous

slow growth of algae slow growth of algae

(important producers).(important producers).

Take the Section 2.2 Quiz