1. Refined determination of metal availability in sediments (Acid Volatile Sulphide measurements) Presentation for the CMA meeting Paris, 17 November Eurométaux Lidia Regoli, Lynette Chung, Katrien Delbeke

2. Proposal for monitoring sediments for EU Metal Risk Assessments
“ Proposal for a multi-metal monitoring campaign aiming at a refined determination of metal availability in sediments”
The proposal was presented and agreed by member states at TC NES III ’06
A Steering Group will be set up composed of : members of the TC NES and/or CMA, monitoring experts from the member states, and Industry representatives.

3. Some backround
Various divalent metals (Cu, Zn, Cd, Pb, Ni,..) show high affinity with sulfides in sediments.
This limits their bioavailability, as they form insoluble metal sulfide complexes
EU metal risk assessments (Zn, Cd, and ongoing Ni, Cu, Pb RAs) recognize the use of the SEM-AVS concept to increase the accuracy of predicting the actual risks of these metals in the sediment compartment.
Application of the SEM-AVS concept :
The SEM-AVS concept can be applied to the local/regional scale using paired measured data.
If not available, the use of a conservative default AVS value can be considered.
SEM-AVS : Simultaneous Extracted Metals – Acid Volatile Sulfides

4. TC NES discussions on choosing a default AVS
The Flanders database: the largest database (n = 200 sediments) available on SEM-AVS data in the EU.
10Percentile AVS based on Flanders database was suggested as default AVS value for Europe
TC NES questioned the representativeness of the Flanders region (and the subsequent derived default AVS) for all of Europe.
Whereas Flanders region is representative of EU lowlands (the Netherlands, Germany, Northern France), not enough data available to evaluate if it is representative for other EU regions.
Proposed way forward for ongoing EU metal risk assessments:
A multi-metallic conclusion i) program aimed at collecting AVS data in relevant river systems in order to fill data gaps in AVS in other EU regions.

5. Selection of relevant EU regions
Focus on identified regions for which little data exists with the final objective to derive representative region-specific default AVS values
Considering :
The WFD distinguishes 26 ecoregions in EU based on fauna living in EU inland waters
FOREGS stream sediment maps (total organic carbon, iron oxides, silicon and sulfur content) show differences in Northern and Southern EU in comparison to EU lowlands.
Choosing particular EU regions relevant for the EU risk assessments (regions where production sites are located)

6. WFD: Distinguishes 26 ecoregions in EU

7. FOREGS : TOC and Silicon content across the EU

8. Selection of relevant EU regions
Northern Europe (Scandinavian countries) (Ecoregion 20 and 22)
United Kingdom (Ecoregion 18)
Belgium (Flanders), the Netherlands, Germany and France (midland river sediments) (Ecoregion 13-14) (already covered by the Flanders AVS)
Southern Europe (Ecoregion 1-3-6)

10. Selection of sampling sites & surfacewater body types within the selected regions
For each of the selected regions focus on:
Main river basins/lakes
Need the collaboration of MS expert to identify these
Depositional sediments from the larger rivers/lakes that are at the higher end of the metal exposure spectrum (e.g. nearby local production sites)
Minimum of 90 samples (30 per region), and depending on possible collaboration of MS who could assist with the sampling as part of their regional / national monitoring campaigns

11. Proposed sampling & analysis methodology
Sediment collection :
Stringent quality assurance/quality control guidelines
Sampling will be conducted in Spring 2007 (April-June 2007)
Laboratory Analysis :
Analysis under approved standard procedures
Data analysis :
Data will be analysed to derive the 10th and 50th Percentile of the AVS for the different regions, that could be then used as a default reasonable worst case and typical value in case no other site specific AVS measurement are available.
The details of the sampling strategy will be discussed with the steering group

12. Conclusion
The AVS sampling campaign will allow for deriving default AVS values relevant for different EU regions where information is currently lacking.
A steering group meeting will be organized to agree on the technical details related to the sampling and analysis.
Sampling program will be conducted in Spring 2007 (April–June 2007)
We solicit the cooperation of Member State experts that could provide logisitic support with regards to the sampling and participation in the steering group.