Transcript "Particulate matter in the Mediterranean Sea: insights into chemical

PERSPECTIVES ON MECHANISMS DRIVING PARTCULATE
ORGANIC CARBON (POC) FLUX: INSIGHTS FROM MEDFLUX
Cindy Lee, Rob Armstrong, Anja Engel, Jianhong Xue, Aaron Beck, Zhanfei Liu, Kirk Cochran, Michael
Peterson, Stuart Wakeham, and Juan-Carlos Miquel
ASLO 2005
Summer Meeting
Ocean Carbon Cycle
Pool units: 1015 gC
Flux units:
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1015
gC/y
Intermediate
and deep ocean
38,100
(from Doney, S.C. and D. Schimel 2002. Global change - The future and the
greenhouse effect. Encyc. Life Sci., Macmillan Publ. Ltd., www.els.net)
Why care about sinking particulate matter?
It is one of the
few processes
that removes C
from the ocean
for long enough
to ameliorate the
increasing CO2
concentration
over time.
Bermuda Atlantic Time-Series Station
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(from USJGOFS Image Gallery)
Sargasso Sea Fluxes
Phytoplankton Biomass
(monthly average)
Organic Carbon Flux
(bimonthly average)
Inorganic Carbon Flux
(bimonthly average)
(Deuser, W.G., F. E. Müller-Karger, R. H. Evans, O. B. Brown, W.E. Esaias and G. C. Feldman. 1990. Surface-ocean
color and deep-ocean carbon flux: How close a connection? Deep-Sea Res. II 37: 1331-1343)
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Ca
Sargasso Sea
Elemental Fluxes
Al
Mg
Sr
(Deuser, W. G., E. H. Ross and R. F. Anderson. 1981.
Seasonality in the supply of sediment to the deep
Sargasso Sea and implications for the rapid transfer of
matter to the deep ocean. Deep-Sea Res. 28: 495–505)
Mn
Ti
Ba
Vx10
I
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Martin Open Ocean Composite Curve
F=1.53(z/100)-0.858
(Martin, J.H., G.A. Knauer, D.M. Karl, W.W. Broenkow. 1987. VERTEX: carbon
cycling in the northeast Pacific. Deep-Sea Res. 34: 267-285)
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Biological Carbon Pump
CO2
N2
fixation of C, N
by phytoplankton
respiration
grazing
excretion
physical mixing
of DOC
aggregate
formation
egestion
Lateral
advection
break up
Base of euphotic zone
active
vertical migration
passive
sinking of
POC, PIC
decomposition
(bacteria)
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consumption,
repackaging
(zooplankton)
Seabed
respiration
excretion
(from OCTET Report, 2000)
POC flux and major biochemical abundances in the
Equatorial Pacific
POC Flux, mg/m d
0.01
1.0
2
Percent of Organic Carbon
0
100
Plankton
20
40
60
80
100
Amino Acid
105 m Trap
Pigment
1000 m Trap
Uncharacterized
Lipid
>3500 m Trap
Sediment
Carbohydrate
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(Wakeham, S. G. and C. Lee. 1993. Production, transport, and alteration of particulate organic matter in the
marine water column. In: M.H. Engel and S. A. Macko (eds) Organic Geochemistry, pp. 145-169. Plenum Press)
Carbon fluxes and concentrations behave differently.
Organic carbon
fluxes decrease with
depth to varying
degrees at different
locations.
The percent of total
mass made up by
organic carbon
reaches a constant
value at depth, ~5%.
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(Armstrong R. A., C. Lee, J.I. Hedges, S. Honjo and S.G.Wakeham. 2002. A new, mechanistic model for organic
carbon fluxes in the ocean based on the quantitative association of POC with ballast minerals. Deep-Sea Res. II,
49: 219-236)
We hypothesized that
ballast minerals on sinking
particles physically protect
a fraction of their
associated organic matter,
and that the ratio of organic
carbon to ballast is key to
predicting variability in
export fluxes and sinking
velocities of organic
carbon.
Labile
Total Flux
Ballast
associated
(Armstrong et al. 2002)
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What should we know about sinking particles?
Are ballast minerals a key to predicting carbon
export?
What role does aggregation play in sinking?
Are ballast and aggregation equally important
throughout the water column?
Do minerals physically protect a fraction of their
associated total organic matter?
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U.S. Collaborators:
European Collaborators:
Lynn Abramson, SUNY
Robert Armstrong, SUNY
Aaron Beck, SUNY
Kirk Cochran, SUNY
Anja Engel, SUNY->AWI
Cindy Lee, SUNY
Zhanfei Liu, SUNY
Michael Peterson, Seattle
Gillian Stewart, SUNY
Jennifer Szlosek, SUNY
Stuart Wakeham, Savannah
Jianhong Xue, SUNY
Scott Fowler, Monaco
Joan Fabres, UB->SUNY
Beat Gasser, Monaco
Madeleine Goutx, Marseille
Catherine Guigue, Marseille
Pere Masqué, UAB
Juan Carlos Miquel, Monaco
Brivaela Moriseau, Brest
Olivier Rageneau, Brest
Alessia Rodriguez y Baena, Monaco
Richard Sempéré, Marseille
Christian Tamburini, Marseille
Elisabet Verdeny, Barcelona
See http://www.msrc.sunysb.edu/MedFlux/ for more information.
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MONACO
Slide 15
MedFlux
Sampling
site
To test ballast ideas we collected sinking particles using sediment traps, in-situ
pumps and nets at the French JGOFS DYFAMED site in the western
Mediterranean.
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Slide 4
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In 2003, mass flux peaked after the spring bloom and rapidly
decreased with time at both 200 and 800 m.
We measured the percent organic carbon in the trap samples. The percent
organic carbon is higher when mass fluxes are lower.
MedFlux Time-series Mooring: March-May 2003
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(Peterson, M.L., S.G. Wakeham, C. Lee, J.C. Miquel and M.A. Askea. 2005. Novel techniques for collection of
sinking particles in the ocean and determining their settling rates. Limnol. Oceanogr. Methods, submitted.)
At 200 m, highest particle flux occurs at rates between 200-500 m/d.
Percent organic carbon is higher at lower settling velocities.
MedFlux Settling Velocity Trap: March-May 2003
(Peterson et al. submitted)
MedFlux 2003
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MedFlux 2003
Positive correlation
Negative correlation
Parameters are: %ASP, GLU, HIS, SER, ARG, GLY, BALA, ALA, TYR, GABA, MET, VAL, PHE, LEU, LYS,
SER+GLY+THR, TAA, LIPIDS, Neuts/TFA, %MASS, Po, Th234, OC/MASS, IC/MASS, TN/MASS
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Elutriator
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Total Mass in Elutriator Fractions (g)
Most material falls at rates greater than 230 m/d.
Th activity was higher at lower settling velocities.
0.8
 Mass
 234Th Activity
Net Trap/Elutriator
0.6
2000
0.4
1000
0.2
0
0
230
115
58
29
Minimum Settling Velocity (m/d)
MedFlux 2003
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3000
1
Organic Biomarkers as Diagenetic Indices
(Sheridan C.C., C. Lee, S.G. Wakeham, and J.K.B. Bishop. 2002. Suspended particle organic composition
and cycling in surface and midwaters of the equatorial Pacific Ocean. Deep-Sea Res. I 49: 1983-2008)
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Principal components analysis of amino acids in elutriated NetTrap samples
Slower sinking
particles
(NT 4 & 5)
Faster sinking
particles
(NT 1-3)
MedFlux 2003
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MedFlux 2003
Opal
May-July
OM
March-May
CaCO3
+ Litho
(Xue et al. In prep)
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MedFlux 2003
Opal
OM
CaCO3
+ Litho
(Xue et al. in prep)
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Laboratory experiment comparing
naked and calcified coccolithophorids
(Lee, Engel et al. In prep)
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MedFlux 2005
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“Unified Ballast-Aggregation Theory of Export”
If mineralized plankton aggregate faster, then
mineralized plankton would be preferentially exported
from the euphotic zone, and aggregation could be
considered as the first step in the association between
carbon and minerals in sinking particles. Ballast may
become more important at depth.
• This narrows the possible theories for preservation at
depth.
• This makes the current acidification of the ocean even
more worrisome as increasing acidification dissolves
forams and coccolithophorids so that there might be
less flux, less organic C export, and thus less CO2
permanently removed from the surface ocean.
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