Use of natural-series radionuclides to understand particle ... · Use of natural-series...
Transcript of Use of natural-series radionuclides to understand particle ... · Use of natural-series...
![Page 1: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/1.jpg)
Use of natural-series radionuclides to understand particle
dynamics and carbon flux in the NW Mediterranean Sea
J.-C. Miquel1, B. Gasser1, S.W. Fowler1,2
1 IAEA Environment Laboratories, Monaco 2School of Marine and Atmospheric Sciences, Stony Brook , USA
IAEA Symposium 2011
![Page 2: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/2.jpg)
Outline DYFAMED site, a unique field lab in the Mediterranean
230Th, a tracer to calibrate trap data
234Th, a tracer for particle export
210Po, a tracer for organic carbon flux
210Po and 234Th in particles and biota
![Page 3: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/3.jpg)
DYFAMED site
![Page 4: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/4.jpg)
DYFAMED site
Unique open sea station in the Mediterranean Sea with a 20yrs time series (hydrodynamic, bio-optics, biogeochemical and biological observations)
Since Jan 2010, Dyfamed is integrated in a large Med network called MOOSE
- Northern current and associated geostrophic front: relatively well isolated from land masses
- Hydrological cycle: winter convection and summer stratification
- Biological cycle: spring plankton bloom
- Atmospheric inputs are important, in particular Saharan dust
![Page 5: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/5.jpg)
biweekly means (1988-2005)
1000 m depth 200 m depth
Flux seasonality
0
100
200
300
Mass F
lux (
mg
m2 d
-1)
0
4
8
12
16
20
PO
C F
lux (
mg
m2 d
-1)
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
0
75
150
225
Sam
ple
d d
ays
0
100
200
300
Mass F
lux (
mg
m2 d
-1)
0
4
8
12
16
20
PO
C F
lux (
mg
m2 d
-1)
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
0
75
150
225
Sam
ple
d d
ays
(Miquel et al., PiO in review)
![Page 6: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/6.jpg)
Phytoplankton and POC flux
-200
-150
-100
-50
0
de
pth
(m
)
0
100
200
300
400
500
600
700
800
900
1000
1100
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Total Chl-a (ng l-1)
Monthly means (1990-2006)
0
3
6
9
12
15
18
P O
C F
l u x
( m
g m
- 2 d
- 1 )
J A N F E B M A R A P R M A Y J U N J U L A U G S E P O C T N O V D E C
Biweekly means (1988-2005)
(Marty et al., DB 2010)
![Page 7: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/7.jpg)
Zooplankton and POC flux
0
3
6
9
12
15
18
P O
C F
l u x
( m
g m
- 2 d
- 1 )
J A N F E B M A R A P R M A Y J U N J U L A U G S E P O C T N O V D E C
Biweekly means (1988-2005)
(Gasser, 1995)
![Page 8: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/8.jpg)
Zooplankton fecal pellets and POC flux
0
3
6
9
12
15
18
P O
C F
l u x
( m
g m
- 2 d
- 1 )
J A N F E B M A R A P R M A Y J U N J U L A U G S E P O C T N O V D E C
Biweekly means (1988-2005)
FP
flu
x (
mg
C m
-2 d
-1)
(Carroll et al., 1998)
![Page 9: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/9.jpg)
Ocean carbon cycle, The biological pump
238U 234Th
210Po 210Pb
230Th
![Page 10: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/10.jpg)
230Th, a tracer to calibrate trap data
![Page 11: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/11.jpg)
230Thlitho,232Thlitho
234Udissolved 230Thdissolved 230Thparticulate
Sinking particles
230Th, a tracer to calibrate trap data
![Page 12: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/12.jpg)
230Thlitho,232Thlitho
234Udissolved 230Thdissolved 230Thparticulate
230Th, a tracer to calibrate trap data
![Page 13: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/13.jpg)
Calculation of trap collection efficiency using 230Th
![Page 14: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/14.jpg)
Calculation of trap collection efficiency using 230Th
year 200m 1000m
1999-2000 187 ± 85% 87 ± 11% (Roy-Barman et al., 2009)
Collection efficiency of traps at Dyfamed:
![Page 15: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/15.jpg)
Calculation of trap collection efficiency using 230Th
year 200m 1000m
1999-2000 187 ± 85% 87 ± 11% (Roy-Barman et al., 2009)
2005 136 ± 47% 96 ± 10% (Roy-Barman et al., unpublished)
2006 46 ± 36% 30 ± 5%
Collection efficiency of traps at Dyfamed:
![Page 16: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/16.jpg)
234Th, a tracer for particle export
![Page 17: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/17.jpg)
Radioactive
Equilibrium
Dep
th
Activity
238U
234Th
Radioactive
Disequilibrium
= 234Th flux
234Th flux = λTh (AU – ATh)dz
(assumes steady state and minimal physics)
• 234Th is highly particle reactive (t1/2 = 24
d) ; 238U is conservative in seawater
• 234Th is removed by scavenging, its
activity is low in surface ocean (particle
scavenging) and increases with depth.
• 238U activity varies as a function of
salinity.
• The shift in 234Th from secular
equilibrium with its parent 238U gives us
an idea of particle flux.
C flux = 234Th flux x [C/234Th]sinking particles
234Th, a tracer for particle export
238U-234Th disequilibria
![Page 18: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/18.jpg)
234ThP
Depth profiles of 234Th activity at Dyfamed site (1994)
(Schmidt et al., 2002)
234ThD 234ThP 234ThT
![Page 19: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/19.jpg)
Depth profiles of 234Th activity at Dyfamed site (2003) (Stewart et al., 2007)
(Cochran et al., 2009)
![Page 20: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/20.jpg)
210Po, a tracer for organic carbon flux
![Page 21: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/21.jpg)
• 210Pb and 210Po are both particle
reactive elements, removed by
scavenging.
• Water column 210Pb (t1/2 = 22 y)
activities are a function of in situ 226Ra
decay (conservative) and atmospheric
deposition.
• 210Po (t1/2 = 138 d) is slightly more
particle reactive than 210Pb. Also, 210Po
is removed preferentially from the water
column through biological activity.
• This enables to examine particle export
on timescales of months.
210Pb-210Po disequilibria
Radioactive
Equilibrium
Dep
th
Activity
210Pb 210Po
Radioactive
Disequilibrium
= 210Po flux
226Ra
Atm. dep
of 210Pb
210Po, a tracer for organic carbon flux
![Page 22: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/22.jpg)
Depth profiles of total 210Po and 210Pb activity at Dyfamed site (2003)
(Stewart et al., 2007)
![Page 23: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/23.jpg)
POC export fluxes at Dyfamed site (2003)
(Verdeny et al., 2009)
![Page 24: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/24.jpg)
• Differences in half-lives
• 234Th tracks all particles
• 210Po tracks only the labile POC pool
(Verdeny et al., 2009)
1:1 line
![Page 25: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/25.jpg)
210Po and 234Th in particles and biota
![Page 26: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/26.jpg)
RN specific activities and particle size at Dyfamed site (March 2005)
(Rodriguez-y-Baena et al., 2007)
![Page 27: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/27.jpg)
RN specific activities and surface:volume ratio in particles (March 2005)
![Page 28: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/28.jpg)
POC : RN ratios and particle size (March 2005)
![Page 29: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/29.jpg)
→ 234Th uptake driven by adsorptive processes
→ 210Po uptake driven by internal bioaccumulation processes
![Page 30: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/30.jpg)
Zooplankton Fecal Pellets
Salps
Pteropods
(Gymnosomata and
Thecosomata)
Euphausiids
Copepods
![Page 31: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/31.jpg)
(Miquel et al., 1994)
C flux vs. fecal pellet flux
Dyfamed-Calvi site, 1986-1988
(Schmidt et al., 1990)
234Th flux vs. fecal pellet flux
r = 0.9
![Page 32: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/32.jpg)
Fecal Pellets
Zooplankton
Organism n POC % Th-234 (dpm/g)
POC/Th-234 (mol/dpm)
Po-210 (dpm/g)
POC/Po-210 (mol/dpm)
Salps 3 6.20 1980 2.61 49.0 104
Euphausiids 3 15.3 1270 10.0 37.9 291
Gymnosomes 3 6.36 1920 2.76 39.1 137
Thecosomes 3 13.0 646 18.0 52.6 187
Copepods 2 16.5 1030 13.4 36.4 377
Organism n POC % Th-234 (dpm/g)
POC/Th-234 (mol/dpm)
Po-210 (dpm/g)
POC/Po-210 (mol/dpm)
Salps 2 1.87 12.8 121 1.14 1360
Euphausiids 3 39.7 3.14 13900 3.38 11500
Gymnosomes body 3 20.4 36.9 527 20.5 762
Gymnosomes cart. 3 4.63 1.62 6660 ND -
Thecosomes 2 17.3 38.6 377 144 109
Copepods 3 40.5 12.9 2660 9.10 3600
![Page 33: Use of natural-series radionuclides to understand particle ... · Use of natural-series radionuclides to understand particle dynamics and carbon flux in the NW Mediterranean Sea J.-C.](https://reader034.fdocuments.us/reader034/viewer/2022043001/5f7bc8580c68bf669110a455/html5/thumbnails/33.jpg)
the end
Thanks