the influence of dust on ocean biogeochemistry; chasing saharan dust storms
DESCRIPTION
The influence of dust on ocean biogeochemistry; chasing Saharan dust storms. Eric Achterberg , Micha Rijkenberg, Polly Hill, Matt Patey, Maria Nielsdottir, Mark Stinchcombe, Jane Heywood, Duncan Purdie, Mike Zubkov, Peter Statham National Oceanography Centre Southampton - PowerPoint PPT PresentationTRANSCRIPT
The influence of dust on ocean biogeochemistry;
chasing Saharan dust storms
Eric Achterberg, Micha Rijkenberg, Polly Hill, Matt Patey, Maria Nielsdottir, Mark Stinchcombe,
Jane Heywood, Duncan Purdie, Mike Zubkov, Peter Statham
National Oceanography Centre Southampton
Claire Powell, Tim Jickells and Alex Baker
University of East Anglia
Manuel Dall’osto and Roy HarrisonUniversity of Birmingham
Ellie HighwoodUniversity of Reading
Overview
• Atmospheric inputs into the ocean
• Poseidon 332 cruise Jan-Feb 2006
• Discovery 3xx cruise Jan-Feb 2008
Dust Inputs to the OceansTg (1012) yr-1
Global Dust Production 1700
Dust Inputs To The Oceans 442
Iron Inputs To The Oceans 15.5
Soluble Iron Inputs To The Oceans 0.15(1% solubility)
N. Atlantic receives largest global dust load
Proximity to Sahara
Modelled dust deposition, Tegen et al. 2005
The North Atlantic: high dust The North Atlantic: high dust inputsinputs
AMT 15 TransectSouthampton, UK - Capetown, S. Africa, September October 2004
(Upwelling Data Excluded)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
-20-16-12-8-40481216202428Latitude (°N)
Dis
solv
ed F
e (n
M)
NEC/CC TSM EqUp GG/SEC STG/BC
Sarthou, Achterberg et al., Deep Sea Res. 2003
Polarstern Anreise cruise 2000
(ii) Hydrocast section data
Dissolved iron (AMT 15)
Ussher, Achterberg, Worsfold, in prep.
Surface water (1000 m) dissolved iron and aluminium (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)
Main hypothesis of our UK SOLAS project:
Atmospheric inputs control rates of primary production and microbial diversity in oceanic waters where nutrients are limiting
Poseidon Cruise POS 332
January 28 – February 23 2006
Objectives of cruise:
1. Provide improved estimate of dust inputs to tropical N Atlantic
2. Determine influence of dust on species diversity, nutrient cycling and N2 fixation
FS Poseidon
MODIS tau-869
Aerosol opt. depth
Surface water dissolved aluminium
nM
Surface water dissolved Fe
Surface water
dissolved free organic Fe binding ligands
nM
Rijkenberg et al., 2007 Submitted to Marine Chemistry
Conditional stability constants of Fe binding ligands in surface water
Open circles: south of Cape VerdeClosed circles: north and east of Cape Verde
CTD FRRF profile for Cape Verde region (typical for cruise)
Nitrogen fixation in the Cape Verde region
MODIS tau-869
Aerosol opt. depth
3 Feb. 14:25
(supplied by Steve Groom et al. PML)
MODIS tau-869
Aerosol opt. depth
4 Feb. 15:10
High volume aerosol filter for February 4, 2006
Claire Powell, UEA
0
20
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120
140
1/27
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1/28
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0
AT
OF
MS
co
un
ts /
ho
ur
dust_1
dust_2
Saharan dust
Cape Verde dust
Dust particles detected during cruise using ATOFMS
Cruise track
1
23
Surface water dissolved Fe
0
0.05
0.1
0.15
0.2
0.25
0.3
first transect second+thirdtransect
[Fe_
dis
s] (
nM
)
n = 16 n = 17
nM
Surface water
dissolved free organic Fe binding ligands
n = 4 n = 3
nM
Rijkenberg et al., 2007 Submitted to Marine Chemistry
Surface water microbial community
Prochlorococcus
Transect dates
Feb 3-4 Feb 10 Feb 11
Ce
lls/m
l
0.0
5.0e+4
1.0e+5
1.5e+5
2.0e+5
2.5e+5
n = 14 n = 7 n = 8
Synechococcus
Feb 3-4 Feb 10 Feb 11
Ce
lls/m
l
0
20000
40000
60000
80000
n = 14 n = 7 n = 8
Picoeukaryotes
Feb 3-4 Feb 10 Feb 11
Cel
ls/m
l
0
1000
2000
3000
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6000
n = 14 n = 7 n = 8
Transect datesTransect dates
Discovery 314 Cruise 2007
• Cancelled due to problems with vessel
Discovery 326 Cruise 2008• Study spatial-temporal variability in atmospheric dust inputs and phytoplankton-bacterial responses
Cruise PlanRegion: transect west of the N Africa into oligotrophic waterslooking for dust stormsCruise track will be guided by satellite observations of dust
Period: 32 days-January 5-February 5
Discovery 326 Cruise 2008Measurements and experiments:
-Dissolved and particulate Fe, Al, Mn analyses-Nanomolar and micromolar nutrients analysis-Microbiology (flow cytometry; FISH; labelled amino acid uptake) -Nitrogen fixation measurements, with NIFH gene determination-DMS measurements and UV exposure studies-Water column light measurements
-Rain and high volume dust collection for subsequent land-based analysis-Real-time ATOFMS measurements of aerosol particles-Low volume dust collection with ship-board dissolution experiments (Bill Landing CLIVAR approach)-Bottle dust dissolution experiments with subsequent dissolved Fe/Al, nutrient measurements-Studies of effect of leached dust solutions on microbial communities-Nutrient addition bioassay experiments (incl. dust additions)
Acknowledgements
Captain and crew of FS Poseidon
NERC-UK-SOLAS for funding the research
Post-doctoral position available at NOCS on Fe biogeochemistry in Iceland-Irminger Basins