Download 2. The Carbon cycle

Biogeochemical Cycles
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THE CYCLING OF NUTRIENTS WITHIN
ECOSYSTEMS
Energy Flow in Ecosystems
July 6, 2017
Biogeochemical Cycles
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 Life on Earth depends on recycling essential chemical elements.
 Biogeochemical cycles move elements between the atmosphere,
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hydrosphere, lithosphere, and biosphere.
Carbon is a necessary building block for most biomolecules
Phosphorus is necessary for DNA, RNA and the energy molecule
ATP
Nitrogen is a key component in proteins, DNA, RNA and many
enzymes
Water is necessary for most chemical functions
Energy Flow in Ecosystems
July 6, 2017
General Nutrient cycle model
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Nutrients cycle
between abiotic and
biotic components
of the ecosystem
Energy Flow in Ecosystems
July 6, 2017
1. The water cycle
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 Water is essential to all
living things
 Typically found in
oceans, lakes, rivers, ice
caps, groundwater (small
amount in atmosphere)
 Cycles via sublimation,
precipitation,
evaporation,
condensation,
consumption,
transpiration
Energy Flow in Ecosystems
July 6, 2017
The Water cycle
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 Water is necessary for most chemical processes in living
organisms.
 The water cycle includes both biotic and abiotic processes.
 Water in oceans, rivers etc. evaporates into the atmosphere.
Energy Flow in Ecosystems
July 6, 2017
 Clouds form when water vapour condenses and water falls back
to the ground in the form of precipitation.
 Water returns to the ocean etc. through runoff or returns to
aquifers through seepage.
 Plants take up water and return unused water to the atmosphere
through transpiration.
 Animals take up water and return it through perspiration,
breathing, and elimination
The Water cycle
Net movement of
water vapor by wind
7(36)
Solar heat
Water vapour
over the sea
Evaporation and
transpiration (59)
Precipitation
over the sea
(283)
Water vapor
over the
land
Precipitation
over the land
(95)
Evaporation
from the sea
(319)
Surface
water and
groundwater
Oceans
Energy Flow in Ecosystems
Flow of water from
land to sea (36)
July 6, 2017
2. The Carbon cycle
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 Carbon is essential to
building organic
molecules
 Can be found in the
atmosphere (CO2),
plants, animals, fossil
fuels, soils, sediments
 Cycles via
photosynthesis,
respiration, combustion,
consumption
Energy Flow in Ecosystems
July 6, 2017
The Carbon Cycle
 CO 2 in the atmosphere diffuses into the water.
 Both land and aquatic plants take in CO 2 and
produce carbohydrates and other biomolecules
through photosynthesis.
2. Carbon Cycle
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 Producers: Plants take in CO2 and make sugar by photosynthesis.
 Consumers: Animals eat plants to get energy (respiration) from
sugar and make proteins from the carbon.
 Breath out CO2 as a waste product of respiration.
 Animals die and dentritus (decomposers) break down the carbon
and other elements back into the soil and air for plants to use
again.
 Human activities such as burning fossil fuels, and cutting and
burning forests puts carbon back into the atmosphere.
Energy Flow in Ecosystems
July 6, 2017
The Carbon cycle
CO2 in
atmosphere
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Photosynthesis
Burning
Producers
Wood and
fossil fuels
Cellular respiration
Higher-level
consumers
Primary
consumers
Decomposition
Detritivores
Detritus
Energy Flow in Ecosystems
July 6, 2017
3.The Nitrogen cycle
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 Found in the atmosphere (it is 80% N2), soils, sediments, water,
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organisms
Nitrogen is part of important biological molecules and limits
plant growth
Nitrogen in nitrate forms are used by plants for production of
amino acids and nucleic acids for protein synthesis and DNA
Animals get amino acids by eating plants or animals that have
eaten plants.
N2 in the atmosphere is FIXED into ammonia (NH3) by nitrogen
fixing bacteria in the soil.
a small amount is fixed during chemical reaction that occur
during lightening storms.
Energy Flow in Ecosystems
July 6, 2017
Nitrogen Fixation by bacteria
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 Plants need nitrogen but cannot take it in from the air.
 Bacteria in the soil on the roots of plants take in nitrogen (N2)
and make ammonia (NH4) which plants can then use to get
nitrogen.
 Ammonification is the breakdown of nitrogen products in waste
and decomposing tissue to return it to the cycle.
 Denitrification is the conversion of ammonia in the soil to free
nitrogen by denitrifying bacteria.
Energy Flow in Ecosystems
July 6, 2017
The Nitrogen cycle
Nitrogen (N2) in
atmosphere
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Detritus
Denitrifying
Assimilation
bacteria
by plants
Nitrates
(NO3– )
Amino
acids and
proteins in
plants and
animals
Detritivores
Decomposition
Nitrogen-fixing
bacteria in root
nodules of
legumes
Nitrogen
fixation
Nitrifying
bacteria
Energy Flow in Ecosystems
Ammonium
(NH4+ )
Nitrogenfixing
bacteria
in soil
July 6, 2017
5. The Phosphorous cycle
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 Important component of
many biological molecules
(nucleic acids, ATP)
 Found in rocks in great
amount, some in soils and
water
 Cycles through
weathering, taken up by
organisms, sedimentation
Energy Flow in Ecosystems
July 6, 2017
The Phosphorus Cycle
 Phosphorus in the rocks
leaches into the soil where
it is taken up by plants.
 Producers make nucleic
acids and when they are
eaten pass the phosphorus
through the food chain to
consumers.
 Phosphorus reenters the
soil through
decomposition and waste.
 The Phosphorous cycle
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Uplifting
of rock
Phosphates
in rock
Weathering
of rock
Phosphates
in organic
compounds
Consumers
Producers
Phosphates
in soil
(inorganic)
Rock
Precipitated
(solid)
phosphates
Energy Flow in Ecosystems
Phosphates
in solution
Detritus
Detritivores
in soil
July 6, 2017