uscg polar star overview & particle export during sofex ken o. buesseler
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USCG Polar Star overview &
Particle export during SOFeX
Ken O. Buesseler
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
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
BC1
BC2
BC3
CTD2
CTD4 CTD6
6 “In” profiles- 5 at highest SF6; 1 shoulder sta.
SF6Goldson et al.
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)
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
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
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
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)
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
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!
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?
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….
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
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
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
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