Transcript 2008, final Lecture 9 Marine Snow

The Biological Pump
Transfer of Energy and Material to the Deep Sea
Formation and Fate of Marine Snow
The ‘Missing’ Carbon
Atmospheric Increases are ~3.2 Gt y-1
Anthropogenic inputs are ~5.4 Gt y-1
~2.2 Gt of anthropogenic Carbon input is
accounted for in the atmosphere, more than half
is missing.
The Biological Pump
Vertical Flux of Organic Particles to the Deep Sea
Sediment Traps
FLUX
gC m-2 d-1
What are sediment traps really measuring?
• Inorganic, organic, and swimming
• Downward fluxes only
• Relative motions and particle sorting
• Statistical funnel
Particle Intercept Trap (PIT)
‘Honjo’ Sediment Trap
Reduction in Vertical Flux over Depth
1
The Martin Curve
50% losses by 300 m
75% losses by 500 m
90% losses by 1500 m
Martin and Knauer 1981
2
3
Explanations for the Shape of the Martin Curve
• Bacterial decomposition = remineralization of Carbon
• Cryptic swimmer distribution
• Smaller, slower sinking particles at depth
Flux = Mass x Sinking Rate
Size distribution of particles in the sea
McCave 1984
Marine Snow
Marine Snow Particles
Marine Snow Particles
Discarded feeding houses
Marine Snow Particles
‘Comets’
Flux = Mass x Sinking Rate
Sinking of particles in the sea
V  d2 x (s-w)
V = settling velocity
d = particle diameter
s = density of particle
w= density of water
Stoke’s Law
Contribution of Marine Snow to Vertical Flux
Narrow window of particle sizes which are large
enough to sink but numerous enough to be widely
distributed.
Cells
Snow
Bodies
2
200
20,000 (um)
cell
chain
plankton
poop
aggregates
Willie
X
1-10 m
50 m
Available to
water column
processes
100 m
2000 m
Aggregates
Composition of Marine Snow
Once living material (detrital) that is large enough to
be seen by the unaided eye.
Described first by Suzuki and Kato (1955)
High C:N makes for poor food quality.
• Senescent phytoplankton
• Feeding webs (e.g., pteropods,
larvaceans)
• Fecal pellets
• Zooplankton moults
Formation of Marine Snow
Type A: Mucous feeding webs are discarded
individually.
Type B: Smaller particles aggregate into larger,
faster sinking particles.
Aggregates
How does Type B Snow Form?
Coagulation Theory: Particle Collision Rates
Differential settling velocities
Turbulent motions
How does Type B Snow Form?
Coagulation Theory: Particle Stickiness
Transparent Exopolymeric Particles
TEPs
Related to bloom conditions of phytoplankton:
• High phyto concentration
• Nutrient depletion
• Self-sedimenting strategy?
Properties of Type B Marine Snow
• High porosity (99% water)
• Carbon source for bacteria and protozoan grazers
(gases often produced)
• Some snow >90% bacteria
• Pore water exchanges dictate chemical gradients
Marine Snow Dynamics
Marine Snow and Surface Production Cycles
Coupled
De-coupled (excesses)
Where will Snow Contribute to Missing Carbon?
Only ~1% of annual new
production reaches sea floor
High Nutrient (Nitrate) - Low Chlorophyll (HNLC)
Eastern Tropical Pacific
Sub-Polar North Pacific
Southern Ocean
Evidence for Iron Limitation in ETP
• Macro-nutrients at non-limiting concentrations
• Small-scale bottle and microcosm experiments
• Natural additions of iron from land nearby
Galapagos Islands
IronEx I
IronEx II
Southern Ocean
www.greenseaventure.com
Ocean Technology Group
(U. of Sydney, Australia)
www.otg.usyd.edu.au
Ocean Carbon Science, Inc.*
(Formerly Carboncorp USA)
www.rsrch.com/carboncorp
Principal
Michael Markels, Jr.
Ian S.F. Jones
Russ George / Robert Falls
Fertilizer
Fe-lignosulphate
or other iron chelate
NH3 solution
Proprietary nutrient supplements,
Fe + ?
GreenSea Venture, Inc.
Organization
Approach
- Fertilizer released along a "spiral
fertilization" path
- Small, floating nutrient pellets
1 t Fe/yr added to HNLC ocean would
capture 30,000 t C/yr [11].
Claimed
Efficacy
600,000 to 2,000,000 t CO2 can be
sequestered by fertilizing 5000 sq. mi. of
Equatorial Pacific Ocean within 20 days
[3].
Equatorial Pacific Ocean
Ocean Area(s)
Targeted for
Fertilization
Claimed Cost Estimate
- Atmospheric nitrogen fixed as ammonia
(NH3) via industrial process (using fossil
fuels)
- Ammonia pumped from a land- or oceanbased (i.e., floating) facility for release into
the surface ocean near the edge of the
continental shelf
- Ammonia discharged via "plurality of riser
pipes"
Adding 1 t N/yr to the ocean sequesters 5 t
C/yr from the atmosphere, even for long-term,
gigaton-scale ocean fertilization application
[12].
Not specified
- Chilean coastal upwelling zone
- Coastal waters of "Low income food
deficient" nations
$7 to $7.5 /tC [3]
- Retrofit commercial ocean liners for releasing
mix into the propeller wash at an "appropriate"
time(s) during a voyage
- Algal response monitored by satellite imaging
and shipboard instrumentation
$18 to $55 /tC [1,2]
- "Plankton domains" along major shipping lanes
Not available
U.S. Patents Filed
Markels, Jr., M., 1995, P/N 5433173, Method of improving production of
seafood.
Markels, Jr., M., 1996, P/N 5535701, Method of increasing seafood
production in the ocean.
Markels, Jr., M., 1999, P/N 5967087, Method of increasing seafood
production in the barren ocean.
Jones, Ian S. F. et al., 1999, P/N 5992089, Process for sequestering into
the ocean the atmospheric greenhouse gas carbon dioxide by means of
supplementing the ocean with ammonia or salts thereof. [Patent for the
Ocean Technology Group at the University of Sydney, Australia. Includes a
schematic for the ‘nourishment’ process.]
Howard Jr., E.G. and O’Brien, T.C. (assignee: E.I. du Pont de Nemours
and Company), 1999, P/N 5965117, Water buoyant particulate materials
containing micronutrients for phytoplankton. [Du Pont’s variant on Markels’
patented idea of floating pellets with embedded iron fertilizer. Specifies a
wide range of compounds for making pellets with.]
Markels, Jr., M., 2000, P/N 6056919, Method of sequestering carbon
dioxide. [Markels’ first patent emphasizing carbon sequestration. Markels’
previous patents were focused upon fish production by fertilization,
although the potential for carbon dioxide capture was also mentioned in
the patents (see below).]
Markels, Jr., M., 2001, P/N 6200530, Method of sequestering carbon
dioxide with spiral fertilization. [Note the incremental, almost annual
"improvements" being made to the patented technology.]
Markels, Jr., M., Filed in 2001, A/N 20010002983, Method of
sequestering carbon dioxide with a fertilizer comprising chelated iron.
[Patent application number six for Markels. Markels proposing a "system"
for tracking sequestered carbon.]
Extreme Deposition: Food Falls
• Rare events (not recorded in traps)
• Deposit large amounts of high quality organic
materials to sea floor (low C:N)
• Rapid sinking, reach 1000s of meters in few days
• Large bodies that remain intact (whales, fish,
macroalgae, etc)
How frequent are food falls?
Deep sea benthic respiration out of balance with traps
~200 kg C km-2 d-1
Same as about 1 fish 5000 m-2 d-1
What impact will that fish have on the deep
sea community?
At 2000 m...
A 10 kg fish will be respired completely...
In 1 DAY over a 0.5 km2 area
In 1 YEAR over a 0.002 km2 area
At 5000 m...
That same 10 kg fish will be respired completely...
In one DAY over a 16 km2 area
In one YEAR over a 0.044 km2 area
Fall event
10 kg
Food fall respired in a 1 m2 area
Carbon
2000 years
Spatial re-distribution of organic material
current
FALL
Particles distributed by feeding
Dissolved Organics
Fecal materials
Rattail or grenadier
Coryphaenoides cinereus
Galatheid crab (Munidopsis sp)
Community response to arrival of food
Local diversity gradient
Non-motile, infaunal
Motile benthic inverts (amphipods, crabs)
Fishes (grenadiers)
Sediment Time-Series
The Statistical Funnel
Siegel and Deuser 1997
Why isn’t the Eastern Atlantic Felimited?