Metal bioavailability under the Water Framework Directive Implementation in monitoring and assessment frameworks Implementation of Bioavailability 1

Introduction User-friendly BLMs and Tiered Approaches Practical challenges – What monitoring data inputs are required? – What if these data aren’t available? – What happens if the water falls outside the validated boundaries? – What do we do with these data? Interpreting the outputs – what does it mean? Monitoring and assessment frameworks – Compliance assessment, – Permitting Questions NOT remaining Questions remaining 2

User-Friendly BLMS and Tiered Approaches Step change? – Effectively, a methodology defined measure – ‘bioavailability’ banded? – Post sampling processing of data Risk-based method for accounting for bioavailability Ambient backgrounds can be considered if needed Step Change? 3

User-Friendly BLMS and Tiered Approaches 4 2. Use of user-friendly BLM

User-Friendly BLMS and Tiered Approaches EQSs are set as dissolved metal under conditions of max bioavailability. Best considered at the most local level possible 5

2. Use of user-friendly BLM User-Friendly BLMS and Tiered Approaches Number of sites Level of potential risk 6

Sweden (n = 3997) 1. Comparison with generic (100% bioavailable) EQS 2. Use of screening tool FAIL Pass Percentage pass rate = 100 % (n =271) (n = 3726) (n =0) (n = 271) For Nickel, with an EQS bioavailable of 2 µg l -1, face-value comparison Use of user-friendly BLM

8

User-Friendly BLMS Run in Excel Algorithms or Look-up tables UK preference is algorithms to make embedding tools into laboratories easier Can automate bioavailability reporting by embedding BLM tools in labs or use offline with monitoring data 9 =(( *pH+( ))*LN(Ca)+( *pH ))*DOC^2+(( *pH+( ))*LN(Ca)+( *pH+( )))*DOC+(( *pH )*LN(Ca)+( *pH+( ))) Zinc PNEC algorithm

Interpreting the outputs One EQS, a generic EQS bioavailable based on very sensitive conditions BLM tool calculates bioavailable metal concentration for direct comparison with the EQS bioavailable 10 Choices..... But the same end result And / Or... Use BLM tool to calculate site specific EQS dissolved using site specific data Then dissolved metal monitoring data compared to site specific EQS dissolved

Natural Backgrounds Need good quality local data for accurate estimation of backgrounds Data not usually available Background correction less scientific than bioavailability Local decision whether to include in WFD classification or investigations Use of user-friendly BLM

12 Effect of backgrounds – England & Wales Zinc

Bioavailability - Practical Challenges What monitoring data are required? Dissolved metal (without this a hazard assessment can still be performed) pH Calcium or a measure of water hardness Dissolved organic carbon (DOC) DOC is crucial for correct assessment…… and is often the one parameter with no data 13

Bioavailability - Practical Challenges What if these data aren’t available? Can develop and use default values, these can be based upon: – Historic DOC data – UV absorbance – Dissolved or total Fe concentrations But DOC is relatively low cost test! 14

Estimating DOC concentrations from other water chemistry parameters DOC concentrations co-vary with some other water quality parameters, such as colour and dissolved iron concentrations. Using relationships derived from locally relevant data, estimates of DOC concentrations can be made (e.g. Fe, UV absorbance)

Estimating DOC concentrations from other water chemistry parameters Predicted No Effect Concentrations for nickel as calculated using matched DOC data and DOC values as estimated using dissolved iron concentrations in over 800 samples from Austria. The solid line gives the 1:1 relationship and the hatched lines are a factor of 2.

Practical Challenges What if the water falls outside the validated boundary conditions? Boundary conditions often ignored with existing EQSs Ca and Low pH boundaries most relevant Can assume 100% bioavailability Or fix at boundary value Or extrapolate Or use ‘special’ EQSs 17

Compliance assessment Annual Average dissolved metal concentrations with annual median DOC, annual average Ca and pH Or..... Assess compliance after each sample has been individually adjusted for bioavailability Whichever method..... Normal face value comparison with optional statistical considerations (sampling error) 18 Probably not too different to current practice? Either use....

Permitting Discharge limits best expressed as dissolved metal? The sensitivity of the receiving water can be accurately reflected in the permit. Bioavailability allows permits to be better related to risk – but might be more complex STW effluents add protecting DOC 19

Questions NOT remaining Accounting for bioavailability-based approaches is not overly complicated There is more than one way of doing it! Conceptually it is similar to the use of hardness-based EQS or methodological defined metrics, such as unionised ammonia The approach can be integrated within current regulatory frameworks 20

Some of the Questions remaining How best to obtain DOC data? Options for waters that fall outside the boundary conditions? Permitting - a national ‘challenge’ ? How & when to include natural backgrounds? And no doubt other questions