Transcript Biogeochemical Cycles

Biogeochemical
Cycles
What is ecology?
 The scientific study of interactions
among organisms and between
organisms and their environment is
ecology.
 The biosphere contains the combined
portions of the planet in which all of life
exists, including land, water, and
atmosphere.
Recycling in the Biosphere
 Matter can be recycled through the
biosphere because biological systems
do not use up matter, they transform it.
– The matter is assembled into living tissue
or passed out of the body as waste
products
 Biological systems pass the same
molecules around again and again
within the biosphere.
– O2 you breath may have been same O2 a
dinosaur used millions of years ago
The Water Cycle
All living things
Require water!
Water Cycle
 During the water cycle, water
molecules enter the atmosphere as
water vapor, a gas. This occurs through
evaporation, which is the changing of
liquid water into water vapor.
– It can also evaporate from the leaves of
plants during transpiration
 Warm, moist air rises. Eventually it
cools and condenses into tiny droplets
that form clouds.
 When water Droplets become large
enough, the water returns to Earth as
precipitation
– Rain, snow, sleet, hail
 On land, water runs along the surface
of the land until it reaches rivers,
streams, lakes, etc…
 Water also seeps into the soil,
where it enters plants through the
roots.
AND THE WATER CYCLE BEGINS ALL
OVER AGAIN!
 The food you eat provides energy
and chemicals that keep you alive.
All the chemical substances that an
organism needs to sustain life are
its nutrients.
The Carbon Cycle
CO2 in
Atmosphere
CO2 in Ocean
Carbon Cycle
 Carbon is a key ingredient in living tissues. It
forms animal skeletons, is an important
component of the atmosphere, and is taken
up by plants in photosynthesis.
 In the atmosphere, carbon is present as
carbon dioxide (CO2). Carbon dioxide is
released into the air by volcanic activity,
burning of fossil fuels, and by decomposition
of organic matter (matter from living organisms)
 Animals CO2 as a waste product of cellular
respiration.
Carbon Cycle
 Plants use carbon dioxide in photosynthesis
to build carbohydrates.
 Carbohydrates are passed along food webs
to consumers. (the animals that eat the plants)
 Breakdown of wastes and dead organisms
return carbon dioxide to the atmosphere.
 In the oceans carbon is found in the form of
calcium carbonate which breaks down and
returns carbon dioxide to the atmosphere.
Nitrogen Cycle
N2 in Atmosphere
NH3
NO3and NO2-
Nitrogen Cycle
 All organisms require nitrogen to make
amino acids, which in turn are used to make
proteins.
 Nitrogen makes up 78% of the Earth’s
atmosphere, but guess what? Even though
nitrogen is in every breath of air we take, our
bodies can’t use this nitrogen….So how is
nitrogen transformed into a form our bodies
can use?
Nitrogen Cycle
 Friendly, bacteria, known as nitrogen-fixing
bacteria live in the soil and on roots of plants
called legumes.
 These bacteria convert nitrogen gas(N2) into
ammonia (NH3) in a process called nitrogen
fixation.
 Other bacteria convert ammonia into nitrates
and Nitrites (NO3- & NO2- ) which consumers
take in when they eat plants!
Nitrogen Cycle
 When organisms die, decomposers return
nitrogen to the soil as ammonia. Some soil
bacterial convert nitrates into nitrogen gas
by a process called denitrification.
Phosphorus Cycle
 Phosphorus is essential to living
organisms because it forms part of
important life-sustaining molecules
such as DNA and RNA.
 Phosphorus does not enter the
atmosphere. It remains mostly on land
in rock and soil minerals and in ocean
sediments.
 It exists as inorganic phosphate.
Phosphorus Cycle
 As rocks and sediments wear down
and are washed into rivers and
streams, the phosphate dissolves.
Plants absorb it.
 It is then bound into organic
compounds which cycle through the
food web, from producers to
consumers, and to the rest of the
ecosystem.
Nutrient Limitation
 If a nutrient is in short supply, it will limit an
organism’s growth.
 Farmers add nutrients to the soil in the form
of fertilizers, which contain nitrogen,
phosphorus, and potassium.
 Open oceans are usually considered
nutrient-poor environments.
 Nitrogen is considered a limiting nutrient
because it cycles very slowly an is scarce in
the ocean.
Nutrient Limitation
 Phosphorus is a limiting nutrient in
freshwater environments.
 When aquatic environments receive a large
supply of limiting nutrient, such as from
fertilizer run-off, there can be a sudden
increase in algae and other producers. This
results in an algal bloom.
– These blooms of algae can disrupt the
equilibrium of an ecosystem.