Heavy Metals: Transboundary Pollution of the Environment

EMEP Status Report 2/2004

I. Ilyin, O. Travnikov, W. Aas, K. Breivik, S. Mano

ABSTRACT

In accordance with the EMEP work-plan for 2004 [ECE/EB.AIR/79/Add.2] the Meteorological Synthesizing Centre - East (MSC-E) and the Chemical Coordinating Centre (CCC) continue research activities in the field of heavy metal atmospheric pollution assessment. The main objective of the work is to evaluate lead, cadmium and mercury pollution levels in Europe on the basis of measurement data and modelling results. Particular attention is paid to cooperation with the effect community on development of the critical load approach, to support of activities on the review of the Protocol on Heavy Metals, and to the evaluation of the MSC-E heavy metal transport model in the framework of preparation to the model review.

National data on anthropogenic emissions of lead, cadmium and mercury for 2002 were submitted to the EN ECE Secretariat by 27 countries. In addition 13 countries presented the revised data for the period of 1990-2001 resulted from the improvement of statistical data, emission factors, calculation methods etc. For the remaining countries expert estimates were used in the assessment. Anthropogenic emissions of lead, cadmium and mercury in 2002 reduced by 11%, 5% and 11% respectively as compared with 2001. The most significant emissions of these heavy metals are from the sources located in Western, Central and Southern Europe.

Heavy metals were included in the EMEP monitoring programme in 1999, though measurements of these substances at individual stations have been carried out since 1988. At present the EMEP monitoring network includes 66 stations measuring lead and cadmium, of which 25 stations measure concentrations of these metals both in the air and precipitation. There are 13 stations, where at least one mercury form is measured. However, the distribution of the monitoring stations over the European territory is not uniform: they are mainly located in Central and Northern Europe. The EMEP monitoring strategy being developed for 2004-2009 will probably improve the spatial coverage of monitoring sites in Euope. Annual analytical intercomparisons of national laboratories processing measurements of heavy metals indicate a substantial improvement of data quality during the period of 1995-2002.

Measurements of heavy metal pollution levels in 2002 showed that the lowest concentrations of lead, cadmium and mercury were observed in Northern Scandinavia. In general concentration levels increase towards the southeast of Europe.

Model estimates of the environment pollution by heavy metals were made by the regional and hemispherical models. According to the modelling results the spatial distribution of environmental pollution levels of heavy metals in Europe is highly non-uniform. The deposition intensity in different parts of Europe can differ by more than an order of magnitude. High deposition levels are characteristic of Central and Southern Europe, the lowest levels - of Northern Europe. Transboundary transport plays an important role in pollution of most of European countries. Contribution of external European anthropogenic sources to depositions in European countries varies from 5 to 85% for lead, 4 - 75% for Cd and 3 - 60% for Hg. The highest contribution is characteristic of the countries with insignificant national emissions and of those bordering powerful emission sources. The most significant contributors of heavy metals to the atmospheric transboundary transport in Europe are the countries with the largest national anthropogenic emissions. The contribution of the transboundary transport to depositions of heavy metals to the European Union varies from 7 to 15%. The bulk of heavy metals (75%) involved in the transboundary transport is emitted only by 10, 9 and 9 European countries for lead, cadmium and mercury respectively.

Pollution levels vary greatly within a country. For example, the annual deposition of lead can differ 3.5 times in different Lands of Germany. Besides, contribution of the transboundary transport to the deposition of lead to different Lands varies from 14 to 46%.

Atmospheric depositions contribute significantly to heavy metal pollution of marginal seas. The highest mean deposition flux of lead was reported over the Black Sea, of cadmium - over the Baltic Sea, and of mercury - over the North Sea.

Hemispheric modeling was applied to the assessment of heavy metal pollution of the new Parties to the Convention - Kazakhstan and Kyrgyzstan. Levels of mercury and lead depositions in these countries were analyzed. It was obtained that about 65% of mercury and 62% of lead depositions to the territory of Kazakhstan are determined by external anthropogenic and natural sources. For Kyrgyzstan the contribution of external sources is even larger - 90% for mercury and 83% for lead.

The MSC-E regional transport model used for the assessment of pollution levels in Europe was evaluated against available measurement data and compared with other models. The evaluation demonstrates a significant correlation of modelling results with measurements. However, the model underestimates lead and cadmium concentrations both in the air and in precipitation and slightly overestimates mercury deposition with precipitation as compared with the observed values.

The activities under the multi-stage project on the intercomparison of mercury transport models are continued. The third stage of the project dedicated to the comparison of the long-term modelling results with the annual and monthly mean measurements of mercury ambient air concentrations and atmospheric deposition fluxes is under way.

In the framework of cooperation with the Working Group on Effects MSC-E operationally calculates relevant parameters of atmospheric inputs to ecosystems. Ecosystem-specific depositions of heavy metals in Europe were assessed and analyzed. To support a preparatory work of the Working Group on Strategies and Review aimed to review the Protocol on Heavy Metals, in particular the work of the Expert Group on Heavy Metals, MSC-E continues preparations for the modelling of heavy metals of the second priority. Emission and monitoring data for these pollutants were collected; information on physical and chemical properties of these pollutants was prepared.
Besides, the EMEP Centres were involved in cooperation with other international organizations and national programmes (AMAP, EU, HELCOM, OSPAR, WMO). The main results were discussed at a number of scientific conferences, workshops and expert meetings. Detailed information about CCC and MSC-E activities can be found at the EMEP website (www.emep.int) and in CCC Report [Aas and Breivik, 2004].