Cycles of Matter

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• Energy and matter move through the biosphere very differently

• Energy has a 1 way flow

• Matter can be recycled within & between ecosystems

• Elements, chemical compounds, & other forms of matter are passed from 1 organism to another, & from 1 part of the biosphere to another, through the biogeochemical cycles

• Biogeochemical cycles connect biological, geological, chemical aspects of the biosphere

Water Cycle

• Water moves between land, atmosphere, and the oceans

• The water cycle consists of evaporation & transpiration, condensation, & then precipitation

• Evaporation – water enters atmosphere from ocean, lakes, & puddles

• Transpiration – water enters atmosphere from plant leaves

• Condensation – water vapor cools and forms clouds, that hold moisture

• Precipitation – moisture droplets in clouds become too heavy, and fall back to Earth

• Water on land runs along surface until it meets a body of water – runoff

• Water also enters soil to replenish ground water levels - seepage

Nutrient Cycles• Nutrients – all chemical substances an

organism need to survive– Chemical building blocks

• Plants get nutrients from environment

• Like water, nutrients are passed between organisms and environment

Carbon Cycle

• Key ingredient in living tissues

• Found in skeletons & rocks as CaCO3

• Found as CO2 in atmosphere– Taken in by plants during photosynthesis, given

off by plants and animals

• 4 main types of processes that move carbon through its cycle

1) Biological processes – photosynthesis, respiration, decomposition

1) Take up & release carbon

2) Geochemical – erosion & volcanic activity1) Release CO2 to atmosphere &oceans

3) Mixed biogeochemical processes – burial & decomposition of dead organisms & conversion under pressure into coal & petroleum

1) Stores carbon

4)Human activities – mining, cutting & burning trees, burning fossil fuels

1) release CO2

Nitrogen Cycle• All organisms require nitrogen to make amino

acids (proteins)

• Nitrogen gas makes up 78% of the atmosphere

• Ammonia (NH3), nitrates (NO3-), & nitrites (NO2-) are found in animal wastes & dead/decaying organic matter

• Nitrogen exists in oceans & other large bodies of water

• Humans add nitrogen to the biosphere (nitrates) when they use fertilizer

Nitrogen in the Biosphere

• Nitrogen fixing bacteria convert N2 gas to ammonia (NH3)

• The bacteria live in soil & on roots of plants called legumes

• This conversion happens in a process called

nitrogen fixation

• Other bacteria in soil convert ammonia to nitrates & nitrites

• Once NO3- and NO2- are available, producers use them to make proteins

• Consumers eat producers and reuse N2 to make their own protein

• When organisms die, decomposers return nitrogen to the soil as ammonia

• Other soil bacteria convert nitrates into nitrogen gas– Known as denitrification– Releases nitrogen into the atmosphere again

Phosphorus Cycle

• Phosphorus is important to organisms because it forms part of DNA & RNA

• Rare in the biosphere

• Does not enter atmosphere

• Found on land in rocks and soil minerals, and in ocean sediments

• Exists as inorganic phosphate

• As rocks and sediments wear down, phosphate is released

• Washed into rivers from land - used by marine organisms

• On land, phosphorus cycles between organisms and soil

• Producers uptake phosphate from soil or water

• Phosphate is then bound to organic compounds

• Compounds move to consumers & then rest of ecosystem

Nutrient Limitation

• Primary productivity of an ecosystem is the rate at which organic matter is created by producers

• Controlled by nutrient availability

• If important nutrient is in short supply – limiting nutrient

• Limiting nutrient – single substance that limits an ecosystem’s productivity

• Reasons for fertilizer– Contain N:P:K -> helps plants grow larger &

more quickly

• Open oceans are considered nutrient poor

– Contain only 1/10,000 amount of N2 as soils

– Nitrogen is limiting agent in salt water

– Sometimes it can be silica or iron

• In freshwater – phosphorus is limiting nutrient

• When an ecosystem receives a large amount of limiting nutrient it results in an algal bloom

• Algal bloom – increase in algae & other producers

• Why? – more nutrients available– Producers can grow & reproduce more quickly– Without consumers, algae can cover surface of

water

• When all nutrients are used up, algae die– Fed on by bacteria– Cause water to become stinky