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Programme INTERREG III : STARDUST

VLIZ. Programme INTERREG III : STARDUST. S patial and T emporal A ssessment of high R esolution D epth profiles U sing novel S ampling T echnologies. Devenir des polluants contenus dans les sédiments fluviaux et marins en zone transfrontalière

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Programme INTERREG III : STARDUST

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  1. VLIZ Programme INTERREG III : STARDUST Spatial and Temporal Assessment of high Resolution Depth profiles Using novel Sampling Technologies Devenir des polluants contenus dans les sédiments fluviaux et marins en zone transfrontalière Lot van de polluenten in fluviatiele en mariene sedimenten in grensoverschrijdende zones Vlaams Institute voor de Zee Université des Sciences et Technologies de Lille Vrije Universiteit Brussel Relationship between the Sulphur cycle and the bahaviour of trace metals in sediments Martine Leermakers Lille, October 26, 2006 Herhaling titel van presentatie

  2. 3 sampling expedition November_December 2005 Wervik, Leie Helkijn, Scheldt Spiere, canal Spiere-Roubaix

  3. Sulphur Cycle

  4. S forms in sediment • AVS: Acid Volatile Sulphide • predominantly FeS, not stable, easily oxidized • CRS: Chromium Reducible Sulphide • predominantly FeS2 (pyrite),to lesser extend S°

  5. Definitions AVS to CRS ratio Degree of sulphurisation Degree of pyritization

  6. definitions Toxicity index: ratio of SEM (simultaneously Extracted metals)/AVS T.I. =  Me (bound to sulfides) (mol/Kg sed.)/ S-AVS (mol/Kg sed.) Log SEM/AVS <0: metals are strongly bound to sulphides and bioavailability is low Log SEM/AVS >0: metals are bound to labile forms such as carbonates and bioaccumulation is high

  7. Redox, pH and alcalinity at the 3 sites

  8. DET porewater profiles

  9. DGT porewater profiles

  10. DGT porewater profiles

  11. DGT porewater profiles

  12. Conclusions • Biogeochemical condition in the Spiere canal different from the 2 other sites • Sulfate in porewater not limiting in the AVS formation • Very high levels of AVS and CRS • Very low values of log SEM/AVS • Low concentrations of total (DET) and labile (DGT) metals in porewater, especially in upper layer • Porewater concentrations increase in deeper layer (>8cm depth) reaching (or exceeding) levels at other sites

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