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INTERREG III: STARDUST

July 2002-December 2002

VLIZ

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Aim• Understanding of fate and mobility of

pollutants in sediments

• requires high resolution profiles of pollutants

Dissolved phase

DGT, DET

Solid phase

Laser ablation ICPMS

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Dissolved phase

DET DGT

•Equibrium of porewater with agarose gel•TOTAL concentration of pollutants

•Binding of trace metals on Chelex resin gel•Preconcentration capability•In sediments: interpretation depends on remobilisation rate from the sediment phase•Only metals which bind on Chelex: SPECIATION

•Free metal ions and weakly bound metals•As: AsIII•Hg: HgII

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DGT, DET

Laboratory experiments

Field work

Method development and Quality Control•Gel preparations•Blanks and detection limits•Reproducibility•Recovery•Linearity•Capability of HR-SF-ICPMS

Application of the method on sediments of the North Sea: Belgian coast

Belgica expeditions:2002/23: October 20022002/29: December 2002

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Advantages of high resolution sector field ICPMS

• High sensitivity; low detection limits• Low sample volume required (1ml)• Posibility to work with variable resolutions:

– low resolution for elements with little isobaric interfences

– Medium and high resolution for elements with important isobaric interferences

• Possible to measure Fe in water and As in seawater: Both elements not possible with normal quadrupole ICPMS

• Fe: ArO intereference• As: ArCl intereference

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Detection limits 25_02_03 calibration blanks (2% HNO3, 1ppb In)

Cd Hg Pb Mn Fe Co Ni Cu Zn AsDL ppt 0.17 8.1 4.2 0.74 29 0.65 5.5 6.2 37 4.8

Detection limits DET 11_03_03 ( stdev blanks DET, dilution 100)

Cd Hg Pb Mn Fe Co Ni Cu Zn AsDL (ppb) 0.04 0.36 0.97 2.60 52 0.13 7 1.97 142 0.05

Calibration detection limits

DET detection limits

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Field work

•Comparison of DGT_DET and classical porewater sampling methods: squeezing and centrifugation•Performed on different sediment types: sandy, muddy, carbonate rich•sediment cores collected with Reynek boxcorer•DGT, DET performed on cores placed in an incubator on deck of the ship (24 hours)

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Reynek boxcorerSediment core

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Presectioned cores held together with plastic mantle

Sectioning of cores and transfer to squeezing pot

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Porewater squeezingsystem

Glovebag: N2 atmosphereprevent oxidation of sediment

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Mn Zeebrugge 2

-16-14-12-10-8-6-4-2024

0 2 4 6 8 10 12

squeez

cent

DGT

DET

Fe Zeebrugge

-14

-12

-10

-8

-6

-4

-2

0

2

4

0 50 100 150 200

squeez

cent

DGT

DET

Mn and Fe profiles (concentrations in ppm), october 2002

Muddy sedimentnear Zeebrugge

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Co Zeebrugge

-14-12

-10-8-6

-4-20

24

0 5 10 15 20

squeez

cent

dgt

Ni Zeebrugge

-14-12

-10-8-6

-4-20

24

0 50 100 150

squeez

cent

dgt

Cd Zeebrugge

-14-12

-10-8-6

-4-20

24

0 0.5 1 1.5 2 2.5

cent

dgt

Pb Zeebrugge

-14-12

-10-8-6

-4-20

24

0 20 40 60 80

squeez

cent

dgt

Trace metal profiles (concentrations in ppb), october 2002

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B2002/23 stat ZB

-14

-12

-10

-8

-6

-4

-2

0

2

4

0 50 100 150 200 250

As µg/L

Fe mg/L

As and Fe DET profiles: Analysis with HR-ICPMS

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Fe Sierra Ventana µg/L

-10-8

-6-4

-20

24

68

0 2000 4000 6000 8000 10000 12000 14000

As Sierra Vantana µg/L

-10-8

-6-4

-20

24

68

0 2 4 6 8 10 12

As,Fe and Mn DET profiles, december 2002

Fe st 700 µg/L

-8-6

-4-2

02

46

810

0 1000 2000 3000 4000 5000 6000

As st 700 µg/L

-8

-6

-4

-2

0

2

4

6

8

10

0 5 10 15

Mn Sierra Ventana µg/L

-10-8

-6-4

-20

24

68

0 500 1000 1500 2000 2500

Mn st 700 µg/L

-8-6

-4-2

02

46

810

0 500 1000 1500 2000

Fe st 701 µg/L

-8-6

-4-2

02

46

810

0 500 1000 1500 2000 2500 3000 3500

As st 701 µg/L

-8

-6

-4

-2

0

2

4

6

8

10

Mn st 701 µg/L

-8-6

-4-2

02

46

810

0 20 40 60 80 100 120

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High resolution profiles in the solid phase

• Sediment impregnation techniques: 2 techniques are being tested:– Polyester resin– Polyethylene glycol

Tests performed on sediments of the North Sea

• Cutting/polishing

• Analysis by LA-ICPMS

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Vacuum impregnation in polyester resin

-sectioning of core-lyophilisation-vacuum impregnation:polester, aceton, hardener

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Polyethyleneglycol (PEG) impregnation

•Equilibation of porewater with PEG for 3 to 5 weeks at 50°C•Lyophilisation

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Perspectives• Application of DGT, DET methods: Scheldt river and

tributaries

• DET-HR-ICPMS: improve detection limits for a number of elements and expand range of elements measured

• As speciation: – DET: Total As

– DGT: AsIII

– coupling of DET with HPLC-AFS?

• Hg speciation– DGT: Chelex: HgII

– DGT: Sumichelate resin: HgII, methylmercury