Heavy Metals: Transboundary Pollution of the Environment

EMEP Status Report 2/2003

I.Ilyin, O.Travnikov, W.Aas, H.Uggerud

ABSTRACT

The main objective of the work is the assessment of lead, cadmium and mercury pollution levels in Europe made on the basis of measurement data obtained at the EMEP monitoring network and modelling results.

National data on anthropogenic emissions of lead, cadmium and mercury for 1990-2001 were submitted to the UN ECE Secretariat by 34 countries. For the remained countries expert estimates were used in calculations. In the majority of European countries emissions of heavy metals tend to decline in the period of 1990-2001. The total emission in Europe has reduced approximately 3.3 times, cadmium - 1.8 times and mercury - 2 times.

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 contains 65 stations measuring lead and cadmium, of which 22 stations measure concentrations of these metals both in air and precipitation. There are 15 stations where at least one mercury form is measured. The monitoring stations, however, are non-uniformly distributed over European territory: they are mainly located in Central and Northern Europe.

Measurements of heavy metal pollution levels in 2001 show that the lowest concentrations of lead, cadmium and mercury are observed in northern Scandinavia. In general concentration levels increase towards the southeast of Europe. The analysis of available long-term measurements demonstrates an essential decrease of concentration levels of lead and cadmium during 1989-2001. Annual analytical intercomparisons of national laboratories treating measurements of heavy metals indicate an essential improvement of data quality during the period of 1995-2002.

Model estimates of the environment pollution by heavy metals were made by the regional and hemispherical models developed in MSC-E. According to the modelling results the emission reduction resulted in the decrease of heavy metal depositions over the major part of European territory. On the whole in the period from 1990 to 2001 lead deposition in Europe decreased 2.7 times, cadmium and mercury - 1.5 times. Less essential decrease of depositions in comparison with the anthropogenic emission reduction is conditioned by the contribution of natural sources, re-emission as well as by global sources of heavy metals.

The spatial distribution of environmental pollution levels of heavy metals 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.

Non-uniform emission reduction of heavy metals in different European countries brings about strengthening the role of the transboundary transport in countries where the reduction rate is most essential. The highest absolute values of the transboundary transport are estimated for countries with large territories and for countries bordering powerful emission sources. In countries with insignificant national emission relative contribution of the transboundary transport to deposition of lead can exceed 70% of the total value, cadmium - 50% and mercury - 40%.

Mercury is a pollutant capable to global transport. The contribution of the intercontinental transport to mercury depositions over Europe is about 40% of the total value. Asian sources and mercury emission from the ocean surface play the most important role.

About half the mercury deposition to such a remote region as the Arctic is due to the transport from anthropogenic emission sources, of which the greatest contribution make European and Asian sources. A special role in the contamination of the Arctic region plays the phenomenon of mercury depletion events, which are responsible for up to 50% of total deposition in the coastal regions of the Arctic Ocean.

In accordance with the "EMEP strategy for 2000-2009" (EB.AIR/GE.1/2000/5) MSC-E has started the preparatory work of evaluation of the environment pollution by heavy metals of the second priority. Pilot calculations of nickel and zinc transport were performed. The computation results were presented at the meeting of the Expert group on heavy metals (Working Group on Strategy and Review).

This year MSC-E proceeds with the assessment of atmospheric pollution loads on different ecosystems in Europe. The obtained results are meant for the Working Group on Effects for the development of critical loads approach.

The activity within the framework of the multi-stage project on the comparison of mercury transport models is also continued. The second stage of the project dedicated to the comparison of modelling results with short-term measurements of mercury in the atmosphere is finished.

The activity of the EMEP Centres was carried out in co-operation with national experts, international organizations and programmes (AMAP, HELCOM, OSPAR, UNEP, WMO, UN ECE/WGEM). The main results were discussed at a number of scientific conferences, workshops and expert meetings.
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