Refined determination of metal availability in sediments

(Acid Volatile Sulphide measurements)

K. Delbeke, on behalf of Metals assoxiations and Euras

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 was set up composed of : members of the TC NES, monitoring experts from the member states, and Industry representatives.

TCNES discussions on 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= 0.77 µmol/g

TC NES questioned the representativeness of the Flanders region for all of Europe.

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 check the default values and fill data gaps in AVS in other EU regions.

TCNES agreement: Selection of EU regionsSelected regions :

- Northern Europe (Scandinavian countries) - United Kingdom - Southern Europe- Midland rivers (already covered by Flanders

Proposal for monitoring sediments for EU Metal Risk Assessments

“ EURAS Proposal for a multi-metal monitoring campaign aiming at a refined determination of metal availability in sediments”

A proposal was presented and agreed by member states at TC NES III ’06

Interests was solicited through TCNES and WFD experts Interests were obtained from Fi, UK, Sp, Dk, De

An AVS Steering Group was set up, composed of experts from the Fi, UK, Sp, Dk ,De, and Ind A first tel conference took place

AVS steering group agreements

MOU drafted by UK, to be signed by all Sediment collection proposal

Sampling rotocol agreed : upper 5 cm, using core sampler or grab sampler

Sampling time agreed : Spring 2007 Sampling sites

Main river basins/lakes Depositional sediments from the larger rivers/lakes that

are at the higher end of the metal exposure spectrum (between 25-75th percentiles of the region specific metal concentrations)

Laboratory Analysis : Analysis under approved standard procedures at VITO

Number if sites and data analysis under discussion Power analysis performed, demonstrating that 25

samples is enough (Dk & De)

EURAS Power analysis for sample size

0

1

2

3

4

5

6

7

0 20 40 60 80 100

Sample size Region

Det

ecte

d di

ffer

ence

bet

wee

n 5

0P F

lande

rs

(n=

200)

and

50P

Reg

ion X

(µm

ol/g

)

Principles1. One sided difference2. Detection of difference

between median values

Flanders 50P= 8.7 µM/g Power analysis (80%)

Statistically power of with 25 samples when:

AVS <4.2 µmol/g

Statistical power ok

4.5 µmol/g

Conclusion

The AVS sampling campaign will allow for extending the derived default AVS values towards other EU regions.

A steering group meeting agreed on the technical details related to the sampling and analysis.

The sampling program will be conducted in Spring 2007 (April–June). Results are expected in Autumn

Current co-operation with MS allows the start of the program Scandinavian country : Finland UK Southern country : Finland Germany decided not to co-operate Additional co-operation with DK would be appreciated

Main conclusions -

Thanks for the co-operation