Biogeochemical cycles

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1. Biogeochemical CyclesBiogeochemical Cycles
Section 22-2
Pages 420-423

2. describe the flow of essential essential
elementselements from the
environment through living
organisms and back into
the environment.
Biogeochemical Cycles

3. Hydrological Cycle

4. Hydrological CycleHydrological Cycle
(water cycle)
1. Reservoir – oceans, air (as water vapor),
groundwater, lakes and glaciers;
evaporation, wind and precipitation
(rain) move water from oceans to
land
2. Assimilation – plants absorb water from the
ground, animals drink water or eat
other organisms which are
composed mostly of water
3. Release – plants transpire, animals breathe
and expel liquid wastes

5. Hydrological CycleHydrological Cycle
1. Reservoir – oceans, air
(as water vapor),
groundwater, lakes and
glaciers; evaporation,
wind and precipitation
(rain) move water from
oceans to land.
2. Assimilation – plants
absorb water from the
ground, animals drink
water or eat other
organisms which are
composed mostly of
water.
3. Release – plants
transpire, animals
breathe and expel liquid
wastes.

6. Carbon Cycle

7. Carbon CycleCarbon Cycle
(carbon is required for building organic compounds)
1. Reservoir – atmosphere (as CO
2
), fossil
fuels (oil, coal), durable organic
materials (for example: cellulose).
2. Assimilation – plants use CO
2
in
photosynthesis; animals consume
plants.
3. Release – plants and animals release CO
2

through respiration and
decomposition; CO
2
is released as
wood and fossil fuels are burned.

9. Carbon CycleCarbon Cycle
1. Reservoir –
atmosphere (as CO
2
),
fossil fuels (oil, coal),
durable organic
materials (for example:
cellulose).
2. Assimilation – plants
use CO
2
in
photosynthesis; animals
consume plants.
3. Release – plants and
animals release CO
2

through respiration and
decomposition; CO
2
is
released as wood and
fossil fuels are burned.

10. Nitrogen Cycle

11. Nitrogen CycleNitrogen Cycle
(Nitrogen is required for the manufacture of
amino acids and nucleic acids)
1. Reservoir – atmosphere (as N
2
); soil (as
NH
4
+
or ammonium, NH
3
or
ammonia, N0
2
-
or nitrite, N0
3
-
or
nitrate

12. 2. Assimilation – plants absorb nitrogen as
either NH
4
+
or as N0
3
-
, animals obtain
nitrogen by eating plants and other
animals. The stages in the
assimilation of nitrogen are as
follows:
Nitrogen Fixation: N
2
to

NH
4
+

by
nitrogen-fixing bacteria (prokaryotes
in the soil and root nodules), N
2 to N0
3
-
by lightning and UV radiation.
Nitrification: NH
4
+
to N0
2
-
and N0
2
-
to

N0
3
-
by various nitrifying bacteria.
Nitrogen CycleNitrogen Cycle

13. 3. Release – Denitrifying bacteria convert
N0
3
-
back

to N
2
(denitrification);
detrivorous bacteria convert
organic compounds back to NH
4
+

(ammonification); animals excrete
NH
4
+

(or NH
3
) urea, or uric acid.
Nitrogen CycleNitrogen Cycle

14. Nitrogen CycleNitrogen Cycle
1. Reservoir – atmosphere (as
N
2
); soil (as NH
4
+
or ammonium,
NH
3
or ammonia, N0
2
-
or nitrite,
N0
3
-
or nitrate
2. Assimilation – plants absorb
nitrogen as either NH
4
+
or as
N0
3
-
, animals obtain nitrogen by
eating plants and other animals.
3. Release – Denitrifying bacteria
convert N0
3
-
back

to N
2
;
detrivorous bacteria convert
organic compounds back to
NH
4
+

; animals excrete NH
4
+
,
urea, or uric acid.

15. Phosphorus Cycle

16. Phosphorus CyclePhosphorus Cycle
(Phosphorus is required for the manufacture
of ATP and all nucleic acids)
1. Reservoir – erosion transfers phosphorus to
water and soil; sediments and rocks that
accumulate on ocean floors return to the
surface as a result of uplifting by
geological processes
2. Assimilation – plants absorb inorganic PO
4
3-

(phosphate)

from soils; animals obtain
organic phosphorus when they plants and
other animals
3. Release – plants and animals release phosphorus
when they decompose; animals excrete
phosphorus in their waste products

17. Phosphorus CyclePhosphorus Cycle
1.Reservoir – erosion transfers
phosphorus to water and soil;
sediments and rocks that
accumulate on ocean floors return to
the surface as a result of uplifting by
geological processes
2.Assimilation – plants absorb
inorganic PO
4
3-

(phosphate)

from
soils; animals obtain organic
phosphorus when they plants and
other animals
3.Release – plants and animals
release phosphorus when they
decompose; animals excrete
phosphorus in their waste products