Critical Loads of Cadmium, Lead and Mercury in Europe

Critical loads are compared to atmospheric deposition of these heavy metals in 1990 and 2000 to assess the risk to human health and the environment. Depositions of heavy metals are computed by the EMEP-Meteorological Synthesizing Centre East using national emissions recorded in official inventories. A tentative comparison is also made between critical loads and the input of cadmium and lead from agricultural practices.

Finally, computed ambient concentrations of lead and cadmium in 2000 are viewed in the context of the first and fourth daughter directives of the European Commission Framework Directive 96/62/EC on ambient air quality assessment and management. Seventeen Parties to the Convention on Long-range Transboundary Air Pollution of the United Nations Economic Commission for Europe participated in the computation and mapping of critical loads. Critical loads of cadmium, lead and mercury were computed by 16, 16 and 9 countries, respectively.

Results showed exceedances to diminish between 1990 and 2000, especially for cadmium and lead. In 2000, the exceedance of critical loads of cadmium only occurs in a few European ecosystem areas. Depositions of lead, however, continue to exceed critical loads in many areas in most of the European countries. The distribution of the risk of mercury does not significantly change over time in the countries that submitted data. A preliminary assessment of fertilisation practices in Europe in 2000 suggests that the resulting lead-input will lead to a further exceedance of critical loads. Accumulation of the agricultural and atmospheric input of cadmium seems to increase the risk of cadmium in a few areas only.

Finally, European guideline and limit values for yearly average ambient concentrations of lead and cadmium respectively, turn out not to be exceeded by computed ambient concentration in EMEP 50W50 km2 grid cells in Europe in 2000. Since atmospheric ambient concentrations and deposition are related (with critical loads of lead and cadmium being exceeded in many areas of Europe), these results suggest that the European guideline and limit values may be less adequate than critical loads for the assessment of the risk of lead and cadmium in the context of long-range transboundary air pollution.