The influence of dust on ocean biogeochemistry chasing saharan dust storms
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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

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The influence of dust on ocean biogeochemistry chasing saharan dust storms

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 Harrison

University of Birmingham

Ellie Highwood

University of Reading


Overview
Overview

  • Atmospheric inputs into the ocean

  • Poseidon 332 cruise Jan-Feb 2006

  • Discovery 3xx cruise Jan-Feb 2008


Dust Inputs to the Oceans

Tg (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)


The North Atlantic: high dust inputs

N. Atlantic receives largest global dust load

Proximity to Sahara

Modelled dust deposition, Tegen et al. 2005


AMT 15 Transect

Southampton, UK - Capetown, S. Africa, September October 2004

(Upwelling Data Excluded)


Polarstern Anreise cruise 2000

Sarthou, Achterberg et al., Deep Sea Res. 2003


(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: (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)Atmospheric inputs control rates of primary production and microbial diversity in oceanic waters where nutrients are limiting


Poseidon Cruise POS 332 (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)

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 (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)

Aerosol opt. depth


Surface water dissolved aluminium (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)

nM


Surface water dissolved Fe (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)


Surface water (nmol/kg) in the Atlantic along CLIVAR A16 (2003; Chris Measures and Bill Landing)

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 Verde

Closed circles: north and east of Cape Verde




MODIS tau-869 surface water

Aerosol opt. depth

3 Feb. 14:25

(supplied by Steve Groom et al. PML)


MODIS tau-869 surface water

Aerosol opt. depth

4 Feb. 15:10


High volume aerosol filter for February 4, 2006 surface water

Claire Powell, UEA


Cape Verde dust surface water

Saharan dust

Dust particles detected during cruise using ATOFMS


Cruise track surface water

1

3

2


n = 16 surface water

n = 17

Surface water dissolved Fe

nM


Surface water 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 surface water

2.5e+5

80000

6000

Picoeukaryotes

Synechococcus

Prochlorococcus

5000

2.0e+5

60000

n = 14

n = 7

n = 8

n = 14

n = 7

n = 8

4000

n = 14

n = 7

n = 8

1.5e+5

Cells/ml

40000

3000

Cells/ml

Cells/ml

1.0e+5

2000

20000

5.0e+4

1000

0.0

0

0

Feb 3-4

Feb 10

Feb 11

Feb 3-4

Feb 10

Feb 11

Feb 3-4

Feb 10

Feb 11

Transect dates

Transect dates

Transect dates


Discovery 314 cruise 2007
Discovery 314 Cruise 2007 surface water

  • Cancelled due to problems with vessel


Discovery 326 cruise 2008
Discovery 326 Cruise 2008 surface water

  • Study spatial-temporal variability in

    atmospheric dust inputs and phytoplankton-

    bacterial responses

    Cruise Plan

    Region: transect west of the N Africa into oligotrophic waters

    looking for dust storms

    Cruise track will be guided by satellite observations of dust

    Period: 32 days-January 5-February 5


Discovery 326 cruise 20081
Discovery 326 Cruise 2008 surface water

Measurements 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 surface water

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


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