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1.1.4 and 2.5.4 Thermodynamics nutrient cycles
Two basic processes must occur in an ecosystem:
1.A cycling of chemical elements.
2.Flow of energy.
Energy flows through systems while materials circulate around
systems.
Cycling of Chemical Elements
TRANSFERS: normally flow through a system and involve a change in location.TRANSFORMATIONS: lead to an interaction within a system in the formation of a new end product, or involve a change of state.
Water “hydrologic” Cycle
Precipitation
Precipitationto ocean
Evaporation
EvaporationFromocean
Surface runoff(rapid)
Ocean storage
Condensation
Transpiration
Rain clouds
Infiltration andpercolation
Transpirationfrom plants
Groundwater movement (slow)
Groundwater movement (slow)
RunoffRunoff
Surface runoff (rapid)Surface runoff (rapid)
Precipitation
Terrestrial carbon Cycle
photosynthesis
aerobic respiration
Terrestrialrocks
Soil water(dissolved carbon)
Land food websproducers, consumers,
decomposers, detritivores
Atmosphere(mainly carbon dioxide)
Peat,fossil fuels
combustion of wood (for
clearing land; or for fuel
sedimentation
volcanic action
death, burial, compaction over geologic time
leaching runoff
weathering
nitrogen Cycle
NO3 –
in soil
Nitrogen Fixation
by industry for
agriculture
Fertilizers
Food Webs On Land
NH3, NH4
+
in soil1. Nitrificationbacteria convert
NH4+ to nitrate
(NO2–)
loss by leaching
uptake by autotroph
s
excretion, death,
decomposition
uptake by autotroph
s
Nitrogen Fixationbacteria convert to
ammonia (NH3+) ; this
dissolves to form
ammonium (NH4+)
loss by leaching
Ammonificationbacteria, fungi convert
the residues to NH3 ,
this dissolves to form
NH4+
2. Nitrification
bacteria convert NO2-
to nitrate (NO3-)
Denitrificationby bacteria
Nitrogenous Wastes, Remains In Soil
Gaseous Nitrogen
(N2)
In Atmosphere
NO2 –
in soil
© 2004 Brooks/Cole – Thomson Learning
Phosphorous Cycle
GUANO
FERTILIZER
ROCKS
LAND FOO
D WEB
S
DISSOLVED IN OCEAN
WATER
MARINE FOOD WEBS
MARINE SEDIMENTS
weathering
agriculture
uptake by autotroph
s
death, decompositio
nsedimentati
on
settling out
weathering
weathering DISSOLVED IN SOIL WATER,
LAKES, RIVERS
uptake by autotroph
s
death, decompositio
n
uplifting over
geologic time
uplifting over
geologic time
miningmining
excretion
excretion
sulfur Cycle
Hydrogen sulfide(H2S)
+Water (H2O)
Sulfur dioxide (SO2)and
Sulfur trioxide (SO3)
Dimethyl(DMS) Industries
Sulfuric acid(H2SO4)
Oceans
+Ammonia (NH2)
+Oxygen (O2)
Ammonium sulfate[(NH4)2SO4]
Animals
Plants
Sulfate salts(SO4
2-)
Hydrogen sulfide(H2S)
Decayingorganisms
Sulfur(S)
Fog and precipitation(rain, snow)
Aerobic conditionsin soil and water
Anaerobicconditions in
soil and water
Volcanoesand
hot springs
Atmosphere
Flow of Energy
Thermodynamics is the study of the energy transformations that
occur in a system.•It is the study of the flow of energy through nature.
•Within a system energy cannot be re-used.
1st Law of Thermodynamics•States that energy can be transferred and transformed, but it CANNOT be created nor destroyed.
•Law of Conservation of Energy.
•Energy of the universe is constant.
Thermal equilibrium = inputs equal outputs over a long period of time.
2nd Law of Thermodynamics•States that every transformation results in a reduction of the FREE ENERGY (useable energy).
•Energy transfers and transformations increase ENTROPY (disorder, randomness or chaos).
•Law of Entropy.
•Energy always tends to go from a more usable (higher quality) form to a less usable (lower quality) form.
•You can’t get something for nothing
•No such thing as a free lunch
Second Law of Thermodynamics
•Any conversion is less than 100% efficient and therefore some energy is lost or wasted.•Usually this energy is lost in the form of HEAT (= random energy of molecular movement). We usually summarize it as respiration.
Solarenergy
Wasteheat
Chemicalenergy
(photosynthesis)
Wasteheat
Wasteheat
Wasteheat
Chemicalenergy(food)
Mechanicalenergy(moving,thinking,
living)
Only 25% of chemical “E” stored in gasoline is transformed in to motion of the
car and 75% is lost as heat!!
Without adding energy to a system, the system will break down .
Heat
Heat
Heat
Heat
Heat
10
100
1,000
10,000Usable energy
available ateach tropic level(in kilocalories)
Producers(phytoplankton)
Primaryconsumers
(zooplankton)
Secondaryconsumers
(perch)
Tertiaryconsumers(human)
Decomposers