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USCG Polar Star overview &
Particle export during SOFeX
Ken O. Buesseler
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Operation personnel, etc.
Export- 234Th WHOI w/on board detectors- K. Buesseler & S. Pike
SF6 WHOI/UEA UK (J. Ledwell, A. Watson)- L. Houghton & L. Goldson
surf. water pCO2 AOML install prior to departure in Seattle(R. Wanninkhof)
Major Nutrients To collect & freeze for later analyses (ancillary team- C. Herbold, K. Mahoney, J. Tegeder, M. Coggeshall)Particles, small
volume- POC/PON/bSi & pigments
WHOI to collect for CHN & bSi (M. Brzezinski- UCSB); pigments (frozen for R. Bidigare, U. Hawaii); C/N isotopes (for M. Altabet)- Ancillary teamParticles, large
volume- 234Th, C/N isotopes
share between Buesseler & Altabet for 234Th & stable C/N work- K. Buesseler & S. Pike
DIC/DOC Collect & return for on shore analyses (F. Millero- U Miami/J. Bauer-VIMS)- R. Daniels
Iron Fe dissolved, total & speciation from Kevlar/bottles & towed fish (P. Croot- IfM & R. Frew- U. Otago, NZ)
Production- primary &bacterial
14C and 3H- (W. Smith-VIMS/R. Barber- Duke and H. Ducklow- VIMS)- C. van Hilst, R. Daniels
Biological Fe stress Fv/Fm- P. Boyd & E. Abraham (NZ)
others salinity, radium (Herbold), bio (chl-C. van Hilst)
Polar Star Science team
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Polar Star cruise- 10 profile stations; 6 In, 4 Out
-67.0
-66.5
-66.0
-65.5
-65.0
-173 -172 -171
B1
BC2
CTD 2
B3
CTD 4
CTD 6
B4
B5
B6
CTD 5
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BC1
BC2
BC3
CTD2
CTD4 CTD6
6 “In” profiles- 5 at highest SF6; 1 shoulder sta.
SF6Goldson et al.
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65 S
67.5
170 W172 W
SOFeX patch as seen from space 4 weeks after iron fertilization
SeaWiFS ocean color
Satellite image- Feb. 12, 2002, F. Chavez et al.
SOFeX patch seen as SF6 peak & Fv/Fm peakThorium-234 indicates similar particle flux in & out of patch (C flux may be elevated, but didn’t see diatom crash)
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Calculate Calculate 234234Th flux from the measured Th flux from the measured 234234Th Th activitiesactivities
Low Low 234234Th = High fluxTh = High flux
Prior Fe Fertilization export data:Prior Fe Fertilization export data:FeEX-II: 6 surface samplesFeEX-II: 6 surface samplesSOIREE: 1 5pt profile and & time-series integralsSOIREE: 1 5pt profile and & time-series integrals(better coverage for EISENEX & SERIES?)(better coverage for EISENEX & SERIES?)
Thorium-234 approach for estimating particle exportThorium-234 approach for estimating particle export
half-life = 24.1 dayshalf-life = 24.1 days
source = source = 238238U parent is U parent is conservativeconservative
sinks = attachment to sinking sinks = attachment to sinking particles and decayparticles and decay
depthdepth(m)(m)
[234Th]
238U
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Melville Feb 3 transect
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-66.4 -66.2 -66.0 -65.8
Latitude
23
4T
h (
dp
m/l
@2
0m
)
0.000
10.000
20.000
30.000
40.000
50.000
SF
6 (
fM)
Thorium
SF6
updated 8/16/02
Melville Feb 13/14 transect
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-173.0 -172.5 -172.0
Latitude
234T
h (
dp
m/l
@
20m
)
0.00
5.00
10.00
15.00
20.00
SF
6 (f
M)
Thorium
SF6
updated 8/16/02
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South to North transect Feb. 18, Polar Star
0
1
2
3
4
5
6
-66.6 -66.1 -65.6
Latitude
SF
6 (f
M)
or
234T
h
tota
l (d
pm
/l)
0
0.2
0.4
0.6
0.8
1
Flu
(sh
ips)
SF6
234Th
Fluupdated 8/16/02
West to East transect Feb. 21, Polar Star
0
1
2
3
4
-173 -172 -171
Latitude
SF
6 (
fM)
or
23
4T
h
tota
l (d
pm
/l)
0
0.2
0.4
0.6
0.8
Flu
(s
hip
s)
SF6
234Th
Flu
updated 8/16/02
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SOFeX time-series progression S-patch"In" stations
Thorium-234 (dpm/l)
1.4 1.6 1.8 2.0 2.2 2.4
Dep
th (
m)
0
20
40
60
80
100
120
140
Jan. 30Feb. 4Feb. 8Feb. 10Feb. 14Feb. 15Feb. 15Feb. 16Feb. 17Feb. 19Feb. 20238U
Highest resolution thorium-234 data setHighest resolution thorium-234 data set
See progression to lower Thorium-234 on See progression to lower Thorium-234 on average during course of SOFeX “In” patch (and average during course of SOFeX “In” patch (and “Out” stations also)“Out” stations also)
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Southern Patch time-series average 0-50m Thorium activity
Days post initial Fe
0 5 10 15 20 25 30Th
ori
um
-234
avt
ivit
y 0-
50m
avg
(d
pm
l-1)
1.2
1.4
1.6
1.8
2.0
2.2
234Th In (w/o last Melville sta)
In Regr dTh/dt = 2.22 -0.026(day) r^2 = 0.97
In 95% conf
234Th out
Out Regr dTh/dt = 1.97 -0.01(day) r^2=0.77
Out 95% conf
last Melville "In" sta (not used in regression)
234Th/t = (238U - 234Th) - PTh + V
where decay rate; PTh = 234Th export flux; V = sum of advection & diffusion
In
Out
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Southern Patch time-series Thorium flux
Days post initial Fe
0 5 10 15 20 25 30
Th
ori
um
-234
flu
x (d
pm
m-2
d-1
)
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
Out NSS model
In NSS model
Thorium-234 flux increasing both “In” and “Out”, but Thorium-234 flux increasing both “In” and “Out”, but significantly larger increased particle flux in Fe fertilized significantly larger increased particle flux in Fe fertilized patchpatch- first time that we see So. Ocean export response to Fe!- first time that we see So. Ocean export response to Fe!
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S-patch In data only
0.0
5.0
10.0
15.0
20.0
26-Jan-02
2-Feb-02
9-Feb-02
16-Feb-02
23-Feb-02
C/T
h (
uM
/dp
m)
0-50m C/Th
50-100m C/Th
S-patch Out data only
0.0
5.0
10.0
15.0
20.0
26-Jan-02
2-Feb-02
9-Feb-02
16-Feb-02
23-Feb-02
C/T
h (
uM
/dp
m)
0-50m C/Th
50-100m C/Th
POC export = POC export = 234234Th flux • [POC/Th flux • [POC/234234Th ]Th ]sinking particlessinking particles
See references by: See references by:
Buesseler, Bacon, Benitez-Nelson, Cai, Charette, Cochran, Coppola, Dunne, Guo, Buesseler, Bacon, Benitez-Nelson, Cai, Charette, Cochran, Coppola, Dunne, Guo, Gustafsson, Hall, Langone, Miller, Moran, Murray, Pates, Roy-Barman, Rutgers vd Gustafsson, Hall, Langone, Miller, Moran, Murray, Pates, Roy-Barman, Rutgers vd Loeff, Santschi, Sarin, Shimmield, Smith, Wei & more …..Loeff, Santschi, Sarin, Shimmield, Smith, Wei & more …..
>53um particles: C/Th below 50m relatively constant>53um particles: C/Th below 50m relatively constant- used in POC flux calculations- used in POC flux calculations
Some evidence of increase C/Th “In” stations 0-50mSome evidence of increase C/Th “In” stations 0-50m- growth of phyto?- growth of phyto?
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Southern Patch time-series POC flux @50m
Days post initial Fe
0 5 10 15 20 25 30
PO
C f
lux
@50
m (
mm
ol C
m-2
d-1
)
6
7
8
9
10
11
12
In NSS model (C/Th = 4.2)
Out NSS model (C/Th = 5.6)
POC flux “In” increased from 7-8 to 11 mmol C m-2 d-1POC flux “In” increased from 7-8 to 11 mmol C m-2 d-1- calculated at 50m- calculated at 50m
Did not see “crash” of Fe induced bloomDid not see “crash” of Fe induced bloom- flux still increasing; high Fv/Fm; still Fe….- flux still increasing; high Fv/Fm; still Fe….
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Does iron fertilization lead to carbon sequestration into the deep ocean via sinking particles?
FeExII- significant C flux (12 days)
SOIREE- little/no C flux (13 days & satellite 55 days)
EisenEx – little/no “C flux” (22 days)
- lack of in/out differences (thorium-234)
SOFeX- small C flux increase (27.5 days since t^0)
- enhanced export “in” vs “out” (subtle changes)
- did not see crash of Fe induced (or natural) bloom
- maintained high photosynthetic efficiency
- low loss terms imply efficient recycling of iron
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SOFeX time-series progression S-patch"Out" stations
Thorium-234 (dpm/l)
1.4 1.6 1.8 2.0 2.2 2.4
Dep
th (
m)
0
20
40
60
80
100
120
140
Jan. 31Feb. 1Feb. 5Feb. 12Feb. 17Feb. 18Feb. 19238U
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SOFeX time-series progression N-patch"In & Out" stations
Thorium-234 (dpm/l)
1.4 1.6 1.8 2.0 2.2 2.4
Dep
th (
m)
0
20
40
60
80
100
120
140
In Jan. 24Out Jan. 25In Feb. 19Out Feb. 20238U
N-patch: see no clear in vs. out or time-series trendN-patch: see no clear in vs. out or time-series trend? hint at 10-20m on Feb. 19? hint at 10-20m on Feb. 19thth
? late station with lower PProd & Chl than Revelle? late station with lower PProd & Chl than Revelle