Presentation on theme: "Katrien Delbeke, ECI, Frank Van Assche,IZA- Europe Frank Van Assche,IZA- Europe On behalf of the Eurometaux Water Project Team Accounting for bioavailability."— Presentation transcript:
Katrien Delbeke, ECI, Frank Van Assche,IZA- Europe Frank Van Assche,IZA- Europe On behalf of the Eurometaux Water Project Team Accounting for bioavailability and natural background under the WFD Perspective of the Metals Industry
Content WFD issues for metals Metal bioavailability Metal background levels Conclusions
Water quality standards setting for metals: issues For the EQS setting on metals, a number of specific characteristics have been recognized: o Some Metals are data-rich and the ecotoxicity data quality is variable o All are Natural Elements, occurring with varying background levels in water o Bioavailability is key to understand the possible ecological impact of metals
From RA to WFD: ecotoxicity data For several metals, EU risk assessments have been made Approved data sets are available RA data sets checked for quality and relevancy But the EU RA = generic assessment on EU-wide scale EU RA = considers uncertainties at an EU wide scale WFD = National (river basin) assessments WFD = more refined approach, more specific to local water conditions WFD = generic + site - specific information (BG & bioavailability) uncertainties reduced for EQS setting
Integrating Metal bioavailability In EQS setting
- -Corrections for metal Bioavailability have been applied in EU Risk Assessments - Cd : Hardness correction on dissolved metal concentrations - Zn, Ni, Cu : BLM correction on dissolved metal concentrations - -Bioavailability phrasing of the WFD (2000/60/EC): - “ In the case of metals the EQS refers to the dissolved concentration” - “…if pH, Hardness and other water quality parameters affect the bioavailability of metals, member states may take this into account when assessing the monitoring results against the EQS” Use of bioavailability in EU regulations
Tiered approach (UK, WFD proposal) Tier 1 : EQS = reference PNEC Check PEC against ref PNEC If exceedence: go to tier 2 Tier 2 : account for metal bioavailability Check PEC against site specific PNEC Tiered approach to account for bioavailability
Evidence on site-specific toxicity for - Cd - - Zn - - Ni - - Cu - -…. Cu Importance of bioavailability for metal toxicity Zn Toxicity of metals to Daphnia magna in different EU surface waters Up to factor 30 difference in EC 50 D.magna explained by bioavailability
The BIOTIC LIGAND MODEL- BLM Principles of metal toxicity: Key target for metal toxicity = gills or gill-like structures
BLM toxicity prediction from water characteristics –zinc example Algae Toxicity predicted within factor 2 Daphnids Toxicity predicted within factor 2 Original unexplained variability : factor After BLM correction : unexplained variability : factor 2-3
Criteria for use of bioavailability in RA & EQS For at least 3 dissimilar groups, for a range of test media, demonstrate, that NOECs variability < factor 5
Scientific evidence : BLM developments & validations - some other species Unexplained variability : from factor 70 to factor 2-3
Bioavailability translator (BLM) « fish, invertebrates, algae » Bioavailability translator (BLM) « fish, invertebrates, algae » SSD Site-specifc EQS Normalised NOECs ( related to site-specific water) Individual NOECs (varying pH, H, DOC,…) Refined Risk ratio = PEC/EQS site Incorporation of Bioavailability in EQS setting
Water chemistry - Rhine pH : 7.8 DOC : 2.8 mg/L Ca : 65mg/L Mg : 11 mg/L Na: 37 mg/L K : 56 mg/L Alkalinity : 119 mg CaCO3/L Full BLM normalization – case example: Cu in the river Rhine Risk in Rhine if PEC dissolved > 8 µg Cu/L Normalisation of NOECs with c-BLM Normalised SSD
Specific EQSs for different EU waters example: Cu
Water parameters driving Bioavailability and available bioavailability tools Key parameters driving bioavailability for Cu, Zn, and Ni are DOC and pH Other drivers can be Ca, Mg, alkalinity, Na,… Dependent of the metal Available tools: Cd: Hardness algorithm Cu, Zn, Ni: user-friendly software for BLM calculations
Remaining issues for discussion under WFD Measurements of bioavailability parameters 1) Temporal variability? make average? 2) Include in all monitoring, or only in cases of exceedences of the ref PNEC? = Tiered approach?
Variability in bioavailability parameters Seasonal versus geographic variability in BLM variables : DOC From : Kramer et al., 2004
Background levels Metals are Natural Elements, occurring in varying background levels Background corrections under the WFD (2000/60EC): - “If natural background values are higher than the EQS member states may take this into account when assessing the monitoring results against the EQS” ISSUES : - How to account for natural background levels - How to set a natural background level
How to account for natural background levels Zn RA and AMPS (2004): added risk approach (ARA) EQS = BRC+ MPA - BRC = background reference concentration - MPA = maximum permissible addition (= PNEC - background test media) In Cd, Pb, Ni & Cu RA, effects are based on total metal levels. EQS = PNEC (site-specific).
Tiered approach (UK, WFD proposal) -Tier 1 : total risk approach (site specific) EQS = PNEC (site-specific) If exceedence: tier 2 -Tier 2 : account for background level EQS = BRC + MPA - BRC = background reference concentration - MPA=maximum permissible addition (= PNEC - background of test media) How to account for natural background levels
How to set natural background levels CMA - AMPS (June 2004) provided some possible methods for BRC values to be chosen in a particular river basin: Analysed values for trace Metal Concentrations in Pristine Areas (with assurance that river basin is pristine or nearly so) Trace Metal Concentrations in Groundwater (shallow and/or deep) Expert Judgement (incl. International agreements; River basin commissions).
How to set natural background levels CMA - AMPS (June 2004) evaluated the FOREGS ambient geochemical baseline data for Europe (http://www.gsf.fi/foregs/geochem/) as possible EU wide reference BRC values The FOREGS database has good merits: - high quality database - consistency in sampling - consistency in sampling and analysis Sampling in unaffected areas - Sampling in unaffected areas BUT, the scale of sampling is rather coarse and THUS, local data are still preferred
Example of Foregs maps
Initial Tiered approach for compliance checking Tier 1 : Reference EQS National pH,DOC…: Within Reference EQS boundaries? Local EQS Within BLM Boundaries? Case by case evaluation Local Background Added EQS Compliance? C diss
Key Conclusions EQS setting needs high quality ecotoxicity data. RA PNECs should be used as a basis, if available. Criteria have been set on the acceptance of bioavailability models (eg BLMs) for use in RA’s and EQS settings. The implementation of background corrections in an added risk approach has been proposed. The derivation of appropriate river –basin specific background values needs to be established. For several metals (Zn, Cu, Ni (almost finalized)),user- friendly bioavailability models have been developed by industry and tested by UK & NL. They are available to water authorities.
The implementation of bioavailability corrections means that bioavailability parameters (pH, DOC, Ca, Mg, Na, alkalinity) are to be measured. Remaining discussions will take place at the EQS- Metal WG Guidance document on metal EQS Bioavailability Background Criteria for need of Sediment and Biota EQS Key Conclusions
Industry recommendation Co-operation between industry and EU-MS, in the framework of RAs and bilateral discussions, will be useful for further methodological development.