Transcript Cycles of Matter - Southgate Schools

Cycles of Matter
3-3
• 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 activity
1) 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