In-situ Particle Sinking Rates and Forms
at Mesopelagic Depths
from the Sub-tropical and Sub-Arctic Pacific
T. Trull, K. Buesseler, C. Lamborg, S.Pike,
C. Moy, S.Bray, F. Ebersbach, S.Manganini
VERTIGO – get some mesopelagic flux
results, examine particle transport controls
25x variability in flux at 1000m :
i) f-ratio ~0.02 to 0.5
ii) b-attenuation 0.6 to 2.0
carrier
Berelson, others.
ballast
VERTIGO–Vertical Flux in the Global Ocean
K2
HOT
SAZ
PFZ
Export from VGPM & Laws
On the shoulders of giants....
•Fowler S. W. and Knauer G. A. (1986)
Role of large particles in the transport of elements
and organic compounds through the oceanic water
column. Progress in Oceanography 16(147-194).
.... sinking rate matters
•Silver M. W. and Gowing M. M. (1991)
The "particle" flux: origins and biological
components. Progress in Oceanography 26, 75-113.
.... look at your samples
In-situ sinking-velocity trap
Peterson et al., 2003; Prime Focus, Inc.
IRS collects for 6 hours,
dumps to carousel below and
repeats cycle for 6 days
5hr 59’
>2m/day
8’
>142
4
Deployed at 300m
2x at K2, 1x at ALOHA
2
1’
>825
Carousel separates
particles into 11
cups.
1’ – all
empty hole –
deploy/recovery
VK2 deployment 1
POC - without swimmers
PC - with swimmers
0.2
Sinking rates
2
2
7
13
27
53
106
142
212
425
0.0
850
fraction of flux
0.4
(meters/day)
VK2 Deployment 2 >425 meters/day
Swimmers? – mainly radiolarian ‘floaters’ with 1 copepod across all
VK2 Deployment 2 – sinking rate fractions
>425 meters/day
>212 meters/day
>142 meters/day
>27 meters/day
on 25mm silver filters
VK2 Deployment 2 >2 meters/day
Polyacrylamide gels for intact particle recovery
Lundsgaard, 1995; Waite and Nodder, 2001; Trull and Moy, 2006
K2 dominated by copepod faecal pellets, and
their aggregates in varying states of decay
(Stephanie Wilson et al. poster OS26A-03;
Friederike Ebersbach et al. poster OS35M-06 )
Control of flux by the distribution of sinking rates?
1. Use observed POC distribution over sinking rates classes (K2 deploy 1)
2. Assume constant first-order decay (exponential loss) for all sinking rates
3. Track particles as they sink and degrade
4. Sum up all contributions at each depth
V K 2 d e p lo y m e n t 1
P O C - w i th o u t s w i m m e rs
0 .2
S in k in g r a te s
2
2
7
13
27
53
106
142
212
425
0 .0
850
fraction of flux
0 .4
(meters/day)
Control of flux by the distribution of sinking rates?
black dotted lines – individual sinking rate classes
blue lines – sum of all classes for different decay rates
green line – Martin power law (b=0.86)
red circle – NBST results from VERTIGO (Buesseler et al.)
0
0m
-500
Martin
-1000
1000 m
-1500
10%
-2000
5%
-2500
-3000
Depth
1% per day
-3500
-4000
-4500
-5000
5000 m
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Flux as fraction of that leaving 100m
1
Conclusions
1. At K2 at 300m depth:
~35% of POC is sinking at 425 to 850 m/day
~80% of POC is sinking at >50 m/day
large copepod pellets dominate the flux
2. A spectrum of initial sinking rates produces a flux
curve of ‘reasonable shape’ without invoking any
changes in processes with depth.
....time for a quick look at PIC ballasting and ALOHA?
Ballast Role for PIC?
POC/PIC (mol/mol)
15
deployment 1
10
5
VERTIGO K2 site
0
0
100
200
300
400
sinking rate (meters/day)
500
Carrier Role for PIC?
P O C v s P IC flu x c o r r e la tio n
POC flux mM/m2-d
0 .4
V K 2 d e p lo ym e nt 1
1 0 % w/w p ro te ctio n
1 0 0 % w/w p ro te ctio n
0 .2
0 .0
0 .0 0
0 .0 1
0 .0 2
P IC flu x m M /m 2 -d a y
0 .0 3
Some very fast sinking POC at ALOHA so higher decay rate required at ALOHA?
(very sparse data)
ALOH A vs. K 2
0 .6
K2 PO C
fraction of flux
0 .5
0 .4
AL O H A P O C
0 .3
0 .2
0 .1
0 .0
> 850
> 425
> 212
> 142
s in k in g r a te (m e te r s /d a y)
>2
V K 2 d ep lo ym en t 2
P O C with s wim m ers
0.2
S inking ra te s (m /da y)
2
2
7
13
27
53
106
142
212
425
0.0
850
fraction of flux
0.4
VK2 Deployment 2 >850 meters/day