Cycles of Matter
Chapter 3 The Biosphere
Section 3-3; pages 74-80
BIOGEOCHEMICAL CYCLES-connecting the
biological, geological, and chemical aspects of the
biosphere
Matter Statement:
Matter within
ecosystems is
recycled within
and between
ecosystems
BIOGEOCHEMICAL CYCLES
Cycle - water, carbon, oxygen,
nitrogen & other elements cycle
from the abiotic (“geo” nonliving
environment) to biotic (“bio”
living organisms) & then back to
the environment.
 Simply put, biogeochemical
cycles pass the same molecules
around again and again within
the biosphere.

biotic
abiotic
BIOGEOCHEMICAL CYCLES
 Most
element
cycles have an
atmospheric
“bank” where the
element is found
in large amounts.
atmospher
e
“bank”
BIOGEOCHEMICAL CYCLES

Elements move from the
“bank” into organisms.



atmosphere
“bank”
Organisms release elements in
daily activities or after death.
Decomposers (or combustion
or erosion) break down organic
matter.
What is the result of their
actions?
RIP
BIOGEOCHEMICAL CYCLES
 Three
example cycles:
– Water
– Carbon (carbon-oxygen)
– Nitrogen
H2 O
C
N
O
WATER CYCLE






evaporation – heating of water from
liquid to atmospheric gas.
condensation – cooling of water from
vapor to tiny droplets that form clouds.
precipitation – droplets too large to be
contained in clouds and water returns to
earth as rain, snow, or hail.
transpiration – evaporation of water from
leaves of plants.
runoff – excess water from precipitation
that comes from streams and rivers and
carried to oceans and lakes.
accumulation – collection of water on
earth.
Refer to Figure 3-11, page 75
Accumulation
http://ga.water.usgs.gov/edu/watercyclesummary.html
CARBON CYCLE
 The
exchange of gases during
photosynthesis and respiration is
a major example of the livingnonliving cycle of carbon-oxygen.
CO2
respiration
photosynthesis
O2
CARBON CYCLE
 How
does carbon enter the living
part of the cycle?
CO2 CO2
CO2
CO2
CO2 CO
CO2
2
CO2
CO2 + H2O ----> C6H12O6 + O2
CARBON CYCLE
 Carbon
is returned to the atmosphere
environment by:
– cellular respiration
– erosion
– combustion
– decomposition
CARBON CYCLE
respiration – process where organisms
obtain energy from breakdown of
glucose.
 photosynthesis – plants use light energy
(sun) to make glucose.
 decomposition – breakdown of dead
organic matter.
 combustion – burning of fossil fuels
(gas, petroleum, coal) which release
CO2 into atmosphere.
 erosion – runoff of soil into body of
water

Carbon Cycle
Refer to Figure 3-13, page 77
http://www.windows.ucar.edu/earth/climate/images/carboncycle.jpg
NITROGEN CYCLE
 79%
of the atmosphere is
nitrogen gas but it is in a form
most living things cannot use.
N2
free
nitrogen
NITROGEN CYCLE
 If
we can’t take in free nitrogen,
how do we acquire it so we can
use it in our bodies?
 Why
do we need
nitrogen in our
bodies?
NITROGEN CYCLE
 How
do we acquire usable
nitrogen?
 Nitrogen-fixing bacteria convert
nitrogen into nitrates.
 Plants absorb nitrates.
 Animals eat plants.
N2
in air
NITRATES
nitrogen-fixing
bacteria
NITROGEN CYCLE
 How
does the nitrogen return to
the atmosphere?
 Denitrifying bacteria convert
the nitrates back into
nitrogen.
denitrifying
bacteria
N2
in air
NITRATES
nitrogen-fixing
bacteria
NITROGEN CYCLE
 Why
do we need nitrogen?
protein
?
Nitrogen
NITROGEN CYCLE
Simplified
Free N2 in
Atmosphere
denitrifying
bacteria
RIP
Organic
material
nitrogen-fixing
bacteria
NITRATES
NITROGEN CYCLE
Simplified






free N2 bank – atmosphere
nitrogen fixation – conversion of atmospheric
nitrogen to ammonia
nitrates – converted form of nitrogen from
atmosphere.
organisms – living things
organic material – components of living things
made of C, H, O, N
denitrification – ammonia and nitrates converted
to nitrogen and released back into atmosphere
Refer to Figure 3-14, page 78
N2 in Atmosphere
NH3
NO3- &
NO2-
All Cycles Are Related