INTERREG III STARDUST July 2002 December 2002 VLIZ
INTERREG III: STARDUST July 2002 -December 2002 VLIZ Brussels, 14/03/03
Aim • Understanding of fate and mobility of pollutants in sediments • requires high resolution profiles of pollutants Dissolved phase DGT, DET Solid phase Brussels, 14/03/03 Laser ablation ICPMS
Dissolved phase DGT DET • 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: As. III • Hg: Hg. II • Equibrium of porewater with agarose gel • TOTAL concentration of pollutants Brussels, 14/03/03
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 Brussels, 14/03/03 Application of the method on sediments of the North Sea: Belgian coast Belgica expeditions: 2002/23: October 2002/29: December 2002
Advantages of high resolution sector field ICPMS • High sensitivity; low detection limits • Low sample volume required (1 ml) • 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: Ar. O intereference • As: Ar. Cl intereference Brussels, 14/03/03
Calibration detection limits DET detection limits Brussels, 14/03/03
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) Brussels, 14/03/03
Reynek boxcorer Brussels, 14/03/03 Sediment core
Presectioned cores held together with plastic mantle Sectioning of cores and transfer to squeezing pot Brussels, 14/03/03
Porewater squeezing system Glovebag: N 2 atmosphere prevent oxidation of Brussels, 14/03/03 sediment
Muddy sediment near Zeebrugge Mn and Fe profiles (concentrations in ppm), october 2002 Brussels, 14/03/03
Trace metal profiles (concentrations in ppb), october 2002 Brussels, 14/03/03
As and Fe DET profiles: Analysis with HR-ICPMS Brussels, 14/03/03
As, Fe and Mn DET profiles, december 2002 Brussels, 14/03/03
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 Brussels, 14/03/03
Vacuum impregnation in polyester resin -sectioning of core -lyophilisation -vacuum impregnation: polester, aceton, hardener Brussels, 14/03/03
Polyethyleneglycol (PEG) impregnation • Equilibation of porewater with PEG for 3 to 5 weeks at 50°C • Lyophilisation Brussels, 14/03/03
Brussels, 14/03/03
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: As. III – coupling of DET with HPLC-AFS? • Hg speciation – DGT: Chelex: Hg. II – DGT: Sumichelate resin: Hg. II, methylmercury Brussels, 14/03/03
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