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Network for the support of European Policies on Air Pollution

Network for the support of European Policies on Air Pollution. The assessment of European control measures and the effects of non-linearities. Non-linearities. Definition. What goes up comes down, the atmospheric mass balance for the emitted reactive pollutants is closed.

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Network for the support of European Policies on Air Pollution

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  1. Network for the support of European Policies on Air Pollution The assessment of European control measures and the effects of non-linearities

  2. Non-linearities

  3. Definition • What goes up comes down, the atmospheric mass balance for the emitted reactive pollutants is closed. • However, the distance scale for the processes of transport, transformation and deposition are large, and differ between the different pollutants (some emitted nitrogen escapes from the European domain, and surface ozone concentrations over Europe are dominated by the advected flux into Europe from the North Atlantic). • In this project, we have identified non-linearities in source-receptor relationships at regional scales in sulphur and nitrogen compounds in air or deposition.

  4. Apparent non-linearities………where for example unknown sources contribute to the deposition • Real non-linearities occur when the processes regulating the lifetime of pollutants change with time (oxidation, deposition)

  5. Three examples • Shipping and the sulphur budget • Changes in dry deposition with time due to changes in SO2 / NH3 3. Oxidized nitrogen budgets

  6. Trends in sulphur deposition throughout the UK 1986-2001 Group 1* : nss-SO42- = -3.25 y + 6542 Group 2* : nss-SO42- = -1.06 y + 2159 Group 3* : nss-SO42- = -0.21 y + 459 Group 4 : nss-SO42- = -0.11 y + 237 * Statistically significant, P < 0.01

  7. Shipping!

  8. Vessel traffic densities for year 2000 based on the sum of reported distributions from AMVER data (AMVER, 2001)

  9. Some areas of the UK show large reductions in acid deposition while other areas (eg Wales and Western Scotland), including some very heavily affected areas have changed little. • Work continues on the influence of shipping emissions on S and N deposition (Univ Oslo) % reduction from 87-01 in total non-marine Sulphur

  10. 2. Has the SO2 dry deposition velocity changed ? • Concentrations are declining faster than expected by models • Current LRT models treat deposition velocity as simply coupled to meteorology and vegetation • LIFE project provides important clues • Is there evidence of regional variations in surface resistance and deposition velocity?

  11. The surface reactions are regulated by SO2/NH3 interactions in suface water films

  12. EMEP 2003 : Total deposition of oxidized S, 2000 mg S m-2 yr-1

  13. 200 0.9 180 0.8 160 0.7 140 0.6 RcSO2 120 0.5 RcNH3 Rc (sm-1) NH4/SO4 100 NH4/SO4 0.4 80 0.3 60 0.2 40 0.1 20 0 0 Speulder Forest Melpitz Auchencorth

  14. Dry deposition rates of SO2 are regulated by chemical processes in water films on terrestrial surfaces. • NH3 is the most important of the pollutants which regulate canopy resistance to SO2 deposition. • Long term rates of SO2 deposition have increased with time as NH3/SO2 ratios have increased. • Non-linearity is introduced into source-receptor matrices by changes in SO2 emission in the presence of significant NH3 concentrations. • Dynamic chemical models are able to reproduce the measured fluxes and resistances of SO2 and NH3 but are not currently applied in Long-Range Transport models.

  15. EMEP model predicts slower trend in ambient SO2 than observed

  16. Sulphur in the UK 1987-2001

  17. Non-linearities in the oxidized nitrogen budgets

  18. NOx emissions Most of the change in emission has already taken place (2005: 50% since late 80’s, only <10% in the next 15 years)

  19. UK Emission deposition and export of atmospheric N 1900-2000

  20. Cause 1 From 1990 to 2010 land-based NOx will decrease from 13.4 to 6.6 Mt While NOx from shipping will increase from 2.8 to 4.6 Mt. So, by 2010, 70% of NOx will originate from shipping (in EU)

  21. Cause 2 NO2 emissions declined ~50% More O3 at night NO2 NO3 HNO3

  22. Exceedances of critical loads of ecosystems for eutrophication by nitrogen in the UK (%)

  23. Detecting the signal of Nitrogen deposition in semi-natural vegetation • 400 1kmx1km survey plots throughout the UK • Species composition and cover 1978, 1980, 2000 • N deposition (Reduced and Oxidized) 5km • Clear signal linking loss of biodiversity to N deposition.

  24. Conclusions • Non-linearities exist and are a cause of regional variation in response to emission changes • Detailed examination of the excellent long term data for air and precipitation composition is a vital step • Models are the tools to summarize our knowledge, for integration, assessment and exploration of the interactions…but they lag behind our understanding of processes

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