Transcript Unit_1_the_living_world part C

Ecosystem Services
o
Important environmental benefits that
ecosystems provide, such as:
•
•
•
Clean air to breathe
Clean water to drink
Fertile soil in which to grow crops
Overview
Natural Biogeochemical Cycles
1.
2.
3.
4.
5.
The Carbon Cycle
The Nitrogen Cycle
The phosphorus Cycle
The Sulfur Cycle
The Hydrologic Cycle (water cycle)
Biogeochemical Cycles
o
Matter moves between
ecosystems, biotic & abiotic
environments, and organisms
•
o
Biogeochemical cycling
involves
•
o
Unlike energy
Biological, geologic and
chemical interactions
Five major cycles:
•
Carbon, Nitrogen, Phosphorus,
Sulfur and Water (hydrologic)
Carbon
o
o
o
o
All living things are composed of carbon
.037% of the atmosphere (approximately)
is composed of carbon as a gas, CO2
It is present in the oceans in several
forms:
Carbonate- CO2-, and Bicarbonate HCO3
3
The Carbon Cycle
o
o
o
o
The global movement of carbon between
the abiotic/biotic environment including
the atmosphere, and oceans and organisms
Producers/Trees act as carbon sinks in
that they store carbon in their tissues
Consumers eat producers/trees and exhale
CO2
When all of the above are decomposed by
decomposers CO2
The Carbon Cycle : Simplified
Units are expressed as 1015g of carbon. Notice that sedimentary rocks and
fossil fuels hold almost all of the worlds carbon…hmm…
The Nitrogen Cycle
o
o
o
Nitrogen is crucial to living organisms
because it is an essential part of biological
molecules such as proteins, and nucleic
acids (RNA/DNA)
The atmosphere is composed of 78%
nitrogen, N2, a two-atom molecule
However atmospheric nitrogen, N2, is
unstable and needs to be “fixed” in order
for it to be “used” by organisms
5 Steps of the Nitrogen Cycle
1.
2.
Nitrogen Fixation: The conversion of
atmospheric nitrogen (N2) to ammonia
(NH3), performed by nitrogen fixing
bacteria. This can happen by combustion,
volcanic action, lightning discharges, and
industrial processes
Nitrification: The conversion of ammonia
or ammonium to nitrate, performed by
nitrifying bacteria; which employ an
enzyme called nitrogenase that helps aid
this process.
5 Steps of the Nitrogen Cycle
cont…
3.
4.
5.
Assimilation: The conversion of inorganic
nitrogen (nitrate, ammonia, or ammonium)
to the organic molecules of organisms
Ammonification: The conversion of
organic nitrogen back to ammonia and
ammonium ions performed by ammonifying
bacteria (circle within the circle)
Denitrification: The conversion of nitrate
to nitrogen gas, performed by
denitrifying bacteria
The Nitrogen Cycle
Values shown are expressed as 1012g of nitrogen/year. The atmosphere holds the largest
pool of nitrogen as N2.
The Phosphorus Cycle
o
o
o
o
Phosporous does not form compounds in
the gaspeous phase, and therefore does
not enter the atmosphere
It cycles from the land (through erosion of
rocks) to the ocean (found in sediments)
It is also found in soils where it is
assimilated into plant tissues
Once inside cells phosphorous is used in
nucleic acids and ATP (adenosine
triphosphate)
The Phosphorous Cycle
o
o
o
Phosphorus cycles in aquatic communities
much in the same way as it does terrestrial
Humans affect the phospohorous cycle by
taking it from one area and using it in
another as fertilizers
Example: Corn from Iowa fatten cattle in
Illinois, the beef is consumed in New York
and the phosphorous enters the NY sewer
systems)
The Phosphorus Cycle
The Sulfur Cycle
o
o
o
There is much uncertainty regarding the
involved in the global sulfur cycle
Sulfur gases enter the air through sea
spray(sulfates SO2/4-), volcanoes (sulfur
di/trioxides SO2&SO3), and dust storms
from deserts (calcium sulfate CaSO4)
Sulfur comprises a minor part of our
atmosphere because it highly reactive as a
gas
Sulfur Cycle
o
Humans can release excess sulfur into the
atmosphere from power plants, factories,
smelting of metal ores and vehicle
combustion which can lead to acid rain
The Sulfur Cycle
The Hydrologic Cycle (water cycle)
o
o
o
Enough said guys…
Know the following terms: evaporation,
condensation, precipitation, transpiration,
runoff, estuary, and watershed.
Understand the role each of these plays in
the Hydrologic Cycle
The Water (Hydrologic) Cycle