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Nutrient Standards: Workshop Birmingham 19-20 February 2013

Workshop conclusions on nutrient standards, uncertainty, and challenges. Recommendations for further work and data requirements from experts. Considerations on comparing values and utilizing standards for biological assessment.

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Nutrient Standards: Workshop Birmingham 19-20 February 2013

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  1. Nutrient Standards: Workshop Birmingham 19-20 February 2013 Geoff Phillips Environment Agency

  2. Objectives of workshop • Understand current standards, the typologies they apply to and their use. • Identify methods used to develop current standards. • Discuss how to deal with uncertainty. • Identify need for further work & additional data requirements • Recommendations to ECOSTAT Present here my conclusions – not discussed with participants following the workshop – Preliminary Conclusions

  3. Experts from 15 countries attended • Austria • Belgium (Flanders) • Denmark • Finland • France • Germany • Hungary • Ireland • Netherlands • Norway • Poland • Portugal • Slovenia • Sweden • UK • Draft notes from meeting prepared and full report will be made available

  4. General points • Remains very difficult to make numeric comparisons • Range of summary metrics • Percentiles, means (annual/summer), maximum • Total and soluble fractions phosphorus • Difference in typologies and regional variations linked to climate and background nutrient levels • Values still being developed/modified for 2nd cycle of WFD • Too few experts from TRAC waters

  5. How to overcome these difficulties • Could use an appropriate dataset to provide conversions for different summary metrics • Identified some common types (based on IC typology) and asked countries to specify their most appropriate standard • Limited success as few countries had overlapping types • Listed the range of standards

  6. Example comparisons from workshop

  7. Range of river G/M P boundaries in other member states

  8. Methods used • More follow up work needed to check summary made at workshop • Different approaches used for HG and GM • General methods are: • Regression models between summary P metric and BQE (mostly as an EQR, but some metrics e.g. chlorophyll a) • Distribution of summary P metric in classes defined using BQE • Literature and expert judgement (few MS) • Different BQEs used (Macrophyte, Algae, Invertebrates)

  9. Uncertainty in standard from the model Phosphorus (annual mean) Biological EQR

  10. How are standards used • Aim of the WFD was to • use biological assessments to determine status • ensure that nutrient levels “support” good status • Will never be a perfect match between nutrient levels and biological status. • Uncertainty higher for rivers than lakes • Two general approaches have emerged • Use a P standard at which high certainty BQE < Good • Use a P standard at which most likely BQE < Good

  11. How are standards used • Use a P standard where high certainty BQE < Good • Upper error band of regression between P and BQE • Higher percentile of P concentration for sites in good status or at good/moderate boundary for BQE • Use a P standard where most likely BQE < Good • Regression line or lower error band • Median of value for sites in good status or at good/moderate boundary

  12. How are standards used • Use a P standard where high certainty BQE < Good • Take action when P standard is exceeded • Use a P standard where most likely BQE < Good • Take action when P standard is exceeded & their is a biological failure Higher Standards Lower Standards

  13. Range of river G/M P boundaries in other member states

  14. Conclusions • Comparing values must consider the way the standard is used • Standards can be indicators of biological status or they can be risk thresholds • Need to be 90% certain that when standard is reached BQE will be < good. Biology likely to drive status • Point at which there is >50% chance that BQE will be < good, or even 10% chance. Nutrient can drive status • Uncertainty in relationship between biology and nutrients is high (typically P explains <20% variation in biology) • Some countries use different approaches for HG and GM boundaries – interpretation of normative definitions

  15. Recommendations • Better documentation would be useful • Values used & summary metric • Method used to derive value • How standards are used • Follow this up for MS attending the workshop • Comparison of standards would require a development of current IC typology – significant and challenging task. • Clearer guidance on purpose and use of supporting element standards

  16. Questions We will finalise the report of workshop, but should we • Contact other MS to ask for information ? • Do further work to agree some appropriate typologies to facilitate comparison of standards ? • How to deal with the way standards are used ?

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