2 Exam Review
ATOC 1060
Exam 2: Friday, Mar 23
3:00-3:50pm
Duane Physics G1B20
Content
Unit 2: The Chemical and Biological
Climate System
Lecture 12 -> Lecture 21
up to and including El Nino
Chapters 8, 9
Quizzes 4, 5, 6
Learning group discussions 4, 5, 6
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Rules
allowed items
pencil
eraser
items NOT allowed
calculator
sheet of equations
computer
textbook
notes
cell phones
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What should I bring?
#2 pencil
good eraser
student ID number
4
Test format
33 multiple choice questions
[3 points each]
Fill in the corresponding bubble on
the scan-tron sheet
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Concept review - Lecture 12
Atoms contain protons, neutrons, and electrons
Chemical elements have atomic mass [periodic table]
Molecules are 2+ atoms held together by bonds
Chemical reactions are expressed with chemical equations
[read & understand chemical equation]
The most abundant gases in the atmosphere are N2, O2, Ar,
and CO2; only CO2 is a greenhouse gas
The total pressure (concentration) of the atmosphere is the
sum of the partial pressures of each individual gas
pCO2 has a seasonal cycle and a multi-decadal increase
[Figure: slide 16]
Steady state means the concentration of the gas/chemical is
constant with time; input balances output
Non-steady state means the concentration of the gas/
chemical changes with time; input and output are imbalanced
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Concept review - Lecture 13
The most abundant elements in the ocean are Cl-, Na+, SO42-,
Mg, and HCO3-; concentration is expressed as mass of
chemical per volume of H2O
Residence time is the average length of time a substance
spends in a given reservoir
Under the assumption of steady state, residence time is
proportional to chemical concentration [qualitative relation]
If chemical residence time is longer than the mixing time of
the ocean, the chemical will be well-mixed
Chemical concentration in the ocean is controlled by both
physical (vertical exchange) and biological (photosynthesis)
processes
Certain ocean chemicals are not in steady state: their
concentration is changing with time. Examples: CO2, CFCs
Deep water formation draws anthropogenic CO2 and CFCs into
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the ocean interior [Figures: slides 18, 19]
Concept review - Lecture 14
The ocean stores 60 times more carbon than the atmosphere
because CO2 in the ocean gets converted to bicarbonate and
carbonate, allowing more CO2 from the atmosphere to diffuse
into the ocean
When CO2 enters the ocean, it reacts with water to form
carbonic acid, bicarbonate, and carbonate [chemical reactions]
The carbon speciation reactions are equilibrium reactions;
changing any part of the carbonate chemistry will result in a
shift in all other species [qualitative understanding]
Most of the dissolved inorganic carbon (DIC) in the ocean is
in the form of bicarbonate; only a small fraction is CO2
Oceanographers measure DIC by adding acid to the seawater
sample; this converts all inorganic carbon to CO2
DIC concentrations are higher in the deep ocean than at the
surface because of the solubility pump and the biological
pump
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Concept review - Lecture 15
Photosynthesis plays an important role in the climate system
by transforming CO2 (greenhouse gas) into organic matter
The atmospheric seasonal cycle of pCO2 is driven by
photosynthesis and respiration in the terrestrial biosphere
[Figure 8-4]
Plants are autotrophs: they can photosynthesize
Photosynthesis converts inorganic materials (CO2, nutrients)
into organic matter (carbohydrates, lipids, proteins, nucleic
acids) and oxygen [photosynthesis chemical reaction]
Terrestrial plant photosynthesis may be limited by low pCO2,
low soil nutrients, low precipitation, and/or low light levels
Leaf photosynthesis occurs in a chloroplast. A series of light
reactions and dark reactions x CO2 into organic matter
Stomata allow for CO2 to diffuse into the leaf; but also
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result in transpiration
Concept review Lecture 16
Net Ecosystem Exchange (NEE) is a measure of how much
carbon is entering or leaving the ecosystem; it is an important
quantity for climate
NEE depends on the rates of gross primary respiration, production,
autotrophic heterotrophic respiration, and
disturbance [Figure: Slide 3]
Autotrophic respiration: plants convert organic matter into
energy; consumes O2, produces CO2
Net primary production: net amount of organic matter produced
by photosynthesis, after accounting for autotrophic respiration
Heterotrophic respiration: decomposition of soil organic matter
by microbes; consumes O2, produces CO2; depends on
temperature
Disturbance: a natural process that disturbs the terrestrial
carbon reservoir (re, pine beetles)
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Concept review - Lecture 17
Phytoplankton are unicellular autotrophs living in the surface
ocean
Diatoms: create a shell (frustule) out of silica
Dinoagellates: small agella; can create red tides
Coccolithophorids: create a shell (coccoliths) out of CaCO3
All phytoplankton contain chlorophyll and perform
photosynthesis
Chlorophyll absorbs strongly in the blue, reects in the
green part of the electromagnetic spectrum [Figure: Slide 10]
Satellites can detect the surface chlorophyll concentration
in the ocean [qualitative understanding]
Phytoplankton photosynthesis is important for the oceans
biological pump [Figure: Slide 15]
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Concept review Lecture 18
The surface ocean chlorophyll concentration is non-uniform:
elevated chlorophyll at Equator, 60o; low chlorophyll at 30o
[Figure: Slide 2]
Phytoplankton take up carbon, nitrogen, and phosphorous
according to the Redeld ratio [understand ratio]
A limitation to photosynthesis is something that impedes the
photosynthetic process
Photosynthesis in the ocean is never limited by H2O or CO2
Light can limit ocean photosynthesis when phytoplankton
leave the euphotic zone and enter the aphotic zone
Photosynthesis can be limited by low nutrient concentrations;
chlorophyll is elevated where surface nutrients are abundant
Nutrient concentrations are elevated at depth; nutrients
return to the surface in upwelling zones
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Concept review Lecture 19
Zooplankton are heterotrophic organisms that are capable of
movement, but not against a current; most are transparent
CaCO3-shelled zooplankton: forams, pteropods
Fish can swim against a current; heterotrophs that absorb
O2 and release CO2
Food webs exhibit bottom-up control when the primary
producers (phytoplankton) control ecosystem structure
Food webs exhibit top-down control when the top predator
controls the ecosystem structure
The maximum sustainable yield of a shery is the maximum
amount of each type of sh that can be caught without
impairing future populations
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Concept review Lecture 20
Coral individuals are called polyps; live in CaCO3 cups
Hermatypic corals contain zooxanthellae: masses of
photosynthetic dinoagellates living within the lining of coral
tissue
Zooxanthellae and corals live in symbiotic relationship: corals
provide protected environment, CO2, nutrients; zooxanthellae
provide oxygen, glucose, and enhance ability for CaCO3
synthesis
Corals grow better in surface ocean (sunlight)
Corals under stress will expel zooxanthellae, leading to
bleaching and coral starvation
Coral skeletons are at risk of disintegration as the ocean
acidies
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Concept review - Lecture 21
El Nino is a coupled atmosphere-ocean climate phenomena
occurring naturally every 3 to 7 years in the Pacic
El Nino is associated with a slackening of the trade winds,
and causes changes in ocean temperature and atmospheric
convection patterns [Figure: Slide 14]
El Nino events are associated with warmer surface
temperatures, reduced upwelling of nutrients, and fewer
phytoplankton in the Eastern Equatorial Pacic
Fisheries observe a decline in sh population in the Eastern
Equatorial Pacic during an El Nino event
El Nino is associated with extreme drought and res in
South-East Asia; this increases the ux of carbon dioxide
from the terrestrial biosphere into the atmosphere; We can
observe changes in the atmospheric pCO2 growth rate during
El Nino events
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Good luck!
Last minute questions?
Visit TA Sean Haneys ofce hours
Special day/location tomorrow:
Thursday, Mar 22, 5-7pm
Ekeley S231
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