Transcript Biogeochemical Cycles

Where are we so far
• Environment defined & explored
• Climate and Climate Change Presented
• Ideas regarding environmentalism,
sustainability, happiness
– There is a crisis and we can approach it from
different directions
• Everyone in Priuses
• Example from Port Alberni, BC
• Moving towards sustainability and happiness
• Places for renewal
• Biogeochemical Cycles
Two Options
• Mt Teneriffe
• Cutthroat Pass
• I-5 to Mt. Vernon,
• I-90 to North Bend,
Highway 20 to Rainy
Mt. Si Road, cont. to
Pass
school bus turnaround
Biogeochemical Cycles - Lecture 1
Class Lecture Goals
1. What are systems?
2. What are biogeochemical cycles?
3. Why are they important?
4. What is common about them?
5. Carbon and nitrogen cycles
6. Water Cycle (Monday)
What is a system?
• System: a collection of matter, parts, or
components which are included inside a specified,
often arbitrary, boundary. Example: Ecosystem
Flux
Flux
• Systems
often have inputs
Cold
Hot and outputs.
Water
• For
dynamic systems,Water
by definition, one or more
Output
aspects of the system change with time.
– Example of a simple dynamic system: bathtub or your
Input
‘bank’ account.
Pool
Heat system is chosen for
• The
boundary
of
a
dynamic
Flux
Loss
convenience -- often the
boundary is arbitrary
Electric
Energy
Carbon
dioxide
Sugar
C-pool
Night
Where are we?
1. What are systems?
2. What are biogeochemical cycles?
3. Why are they important?
4. What is common about them?
5. Carbon and nitrogen cycles
6. Focus on the Water Cycle (Monday)
What are biogeochemical cycles?
• Earth system has four parts
–
–
–
–
Atmosphere
Hydrosphere
Lithosphere
Biosphere
• Biogeochemical cycles: The chemical
interactions (cycles) that exist between
the atmosphere, hydrosphere,
lithosphere, and biosphere.
• Abiotic (physio-chemical) and biotic
processes drive these cycles
• Focus on carbon and water cycles (but
could include all necessary elements for
life). N - cycle weakly touched on!
What is common amongst them?
• Each compound (water, carbon, nitrogen)
typically exists in all four parts of the Earth
System
• Biologically useful forms are usually in low
concentrations or quantities
• There are
– ‘Pools’
– Fluxes in and out of pools
– Chemical or biochemical transformations
• Transformations
– are important
– can lead to positive & negative consequences
Transformations
Policy Issue:
Examples
of Transformations
Trees
capture
carbon,
1.
Carbon
cycle:
Organic compounds to CO2
Carbon
is storedrespiration,
in trees decomposition, or fire)
(processes:
Carbon
can cycle:
be released
(respiration,
decomposition)
2.
Carbon
CO2 toslowly
organic
compounds
(process:
Or photosynthesis)
Rapidly
(fire) cycle: N2 to NO3 (atmospheric nitrogen to
3.
Nitrogen
plant utilizable nitrate) (process: N-fixation)
4.
Nitrogen
Policy
Issue:cycle: N2 to NH3 (plant utilizable ammonia)
(process:
Haber-Bosch
Industrial
N-fixation)
Rapidly
growing
plants (trees
or crops)
need nitrogen
5.
Water cycle: Liquid water to water vapor (process:
fertilizer
evaporation
and from
evapo-transpiration)
Fertilizer
can come
organic and non-organic sources
6.
Watersources
cycle: Water
vapor to liquid water (process:
Organic
are inefficient
condensation)
Inorganic
sources are fossil fuel intensive
Where are we?
1. What are systems?
2. What are biogeochemical cycles?
3. Why are they important?
4. What is common about them?
5. Carbon and nitrogen cycle
6. Focus on the Water Cycle (Monday)
Carbon Cycle
5000
http://www.epa.gov/climatechange/kids/carbon_cycle_version2.html
Carbon Cycle Data
760
• Burning of fossil
fuels
• Land conversion
• Cement
• Role of Oceans
• Role of terrestrial
plants (trees &
soils)
Lithosphere
Increase biological C fixation
• Focus on oceans
• Proposal to add iron
• Where did idea come from?
• Would it work?
Buesseler & others suggest the following
about ocean Fe fertilization
1. Unclear how long
effect lasts
2. Do not understand
all the potential
biogeochemical
impacts
3. Impact potentially
small
4. Effects on other
greenhouse gases
is non-existent or
small
61%
28%
6%
1
6%
2
3
Pick the false statement
4
Changes in Atmospheric C02
QuickTime™ and a
decompressor
are needed to see this picture.
Key Aspects of the Carbon Cycle
•
•
•
•
Carbon is the skeleton of all life.
Foundation of the food chain or web
Foundation of fossil fuels
Foundation of ‘carbon-neutral’ based fuels
– Ethanol
– Cellulosic biofuels
– Biodiesel
• Carbon dioxide is a critical gas:
–
–
–
–
Taken up by plants in photosynthesis
Released by plants and animals in respiration
Released during decomposition (and fires)
Greenhouse gas
Question: Photosynthesis is
an example of a pool
65%
1. True
2. False
35%
1
2
Where are we?
1. What are systems?
2. What are biogeochemical cycles?
3. Why are they important?
4. What is common about them?
5. Carbon and nitrogen cycle
6. Focus on the Water Cycle (Monday)
Nitrogen Cycle
Forms ofForms:
Nitrogen (N2)
Biological
1. N2 - inert gas, 78% of the atmosphere
2. NO,
N20, NO
gases of nitrogen,
Plants:
Nitrate
(NO2 3--)other
and ammonium
(NH4+) not directly
biologically important. Part of the gases found in
smog.
Plants
to animals (amino acids, proteins)
3. NO3- (nitrate) and NH4+ (ammonium) -- ionic forms of
nitrogen
that(amino
are biologically
usable.
Animal
to animal
acids, proteins)
http://soil.gsfc.nasa.gov/NFTG/nitrocyc.htm
Biological Nitrogen Sources over Time
Nitrogen Cycle: Key Points
• Nitrogen is in the atmosphere as N2 (78%)
• N2 is an inert gas and cannot be used by plants
or animals
• N2 can be converted to a usable form via
– Lightening
– N-fixing micro-organisms (free living, assoc. with plant)
– Industrial process (energy intensive)
• Plant growth is often limited by low soil nitrogen
• Nitrogen is easily converted & lost from biological
systems (e.g., fire)
Knowing something about the
carbon and nitrogen cycle we will
explore corn ethanol as a source of
energy
• Constraints:
– Not a discussion of energy independence
or balance of trade
• An assessment of how corn is involved
in the C and N cycles.
• How we must follow the first and second
laws of thermodynamics
Burning dried plants or compounds
from dried plants is similar to recycling
64%
36%
1. Yes
2. No
1
2
Theoretically, burning ethanol from corn vs.
burning oil should reduce the rate we are
adding carbon dioxide to the atmosphere.
1. True
2. False
71%
29%
1
2
What are the two laws of
thermodynamics?
• Conservation of Energy: Energy can be
transformed from one form to another form;
energy cannot be created nor destroyed.
– Example: Light energy from the sun is converted to
chemical energy represented by the energy in
chemical bonds (carbon-carbon units in sugar).
• Entropy: Each transformation results in heat
production and therefore the form of energy
becomes increasingly less able to do work.
– Example: Inefficiency of
• Photosynthesis
• Food chain
Steps in Ethanol Production
• Sun -- Sugar -- corn plant
• Corn plant -- sugar -- ethanol
• Carbon dioxide produced in
– Farming
•
•
•
•
Planting
Fertilizing and fertilizer production (N)
Irrigation
Harvesting
– Transportation
– Processing
– Distribution
Purely from a Carbon and Nitrogen
cycling consideration, ethanol
production …
1. Is clearly an
outstanding strategy
2. Is a strategy worth
considering
3. Is a strategy worth
considering, but with
proper cautions
4. Is a totally bad idea
5. I walk & bike and its
not my problem
1
2
3
4
5
Summary
•
•
•
•
•
1. What are systems?
2. What are biogeochemical cycles?
3. Why are they important?
4. What is common about them?
5. Carbon and nitrogen cycles
• Monday: water cycle