Trends in Impacts of Long-range Transboundary Air Pollution : Technical Report prepared by the Bureau, the International Cooperative Programmes (ICP) of the Working Group on Effects

1999

80 S.

Zahlr. Abb., Tab., Lit. Ang.

Bandaufführung

1-870393-52-X

14223

54526

Decreases in emissions of sulphur over the last 20 years have resulted in less deposited acidity throughout Europe and North America. These decreases are linked to the observed recovery of the chemistry and biology in freshwaters and the falling rate of corrosion of materials in many parts of the ECE region. Acidity critical loads exceedances are falling and are predicted to fall further in the future. However, nitrogen emissions remain high, causing widespread and continuing eutrophication of natural ecosystems as well as acidification. As a consequence, improvements in exceedances of nutrient nitrogen critical loads are small. Forest condition shows continued signs of deterioration in some parts of Europe; the results are confounded by stress factors other than air pollution which is still seen as a predisposing or triggering factor for forest damage. Dynamic modelling studies show that recovery from acidification often will be slow and that long-term recovery is influenced more by the decrease in deposition than its timing. Measurement of ozone concentrations in the monitoring programmes reflect the marked yearly variation and geographical differences reported by EMEP. Effects of ozone on crops are widespread and follow the yearly changes of pollutant concentrations, but there are no apparent trends since 1992.