ATMOSPHERIC HEAVY METALS WITHIN THE ECE REGION

Torunn Berg

Chemical Coordination Centre of EMEP (EMEP/CCC) P.O. Box 100, N-2007 Kjeller, Norway

Phone +47 63 89 82 49, Fax: +47 63 89 80 50, E-mail: torunn.berg@nilu.no

INTRODUCTION

Heavy metals were not a part of EMEP’s monitoring program before 1999. Co-operation concerning heavy metals between EMEP and other international programs was, however, extended from 1996. As a first step CCC developed a database and the participants were asked to deliver data from existing heavy metal networks (e.g. OSPAR, HELCOM, AMAP, MEDPOL).

It is recommended that the future works under the Convention should concentrate on eighth priority elements: lead (Pb), mercury (Hg), cadmium (Cd), chromium (Cr), nickel (Ni), zinc (Zn), copper (Cu) and arsenic (As). Particular attention should be paid to the first three elements.

Since 1996 annual datareports on heavy metals have been published in the framework of EMEP. The majority of the data are included in the priority lists for heavy metals.

MAPS OF HEAVY METAL CONCENTRATIONS OVER EUROPE

Annual averages of Pb and Cd from the 1997 precipitation data are presented in maps (Figures 1-2). The yearly precipitation mean concentrations have been calculated from daily, weekly or monthly reported values as precipitation-weighted averages.

The element concentrations were interpolated from irregular to regular grids using ordinary kriging (Journel and Huijbregts, 1981). The method makes use of the spatial correlation between the measured data, and estimates data values where no measurements exist. The kriging weights are computed from a variogram, which measures the degree of correlation among sample values in the area as a function of distance and direction of samples. The whole EMEP-area consisting of 99x99 grid elements were kriged. One element is 50 x 50 km. It should be noted that the estimation error of concentrations in grid elements distant from the sites can be considerable and that a lack of sites in regions with characteristic high or low concentration will result in a corresponding lack of this feature in the presented maps.

Lead in precipitation

The stations have been located away from local sources and are as far as possible representative for a larger region. The lowest concentrations of Pb during 1997 are found in northern Scandinavia and Portugal, where the annual averages are below 1 µg Pb/l (Figure 1). Increasing gradients can be seen southwestward and south-eastward with peaks around 4 µg Pb/l at Czech and English stations. Usage of Pb in petrol (or as petrol additive) has decreased much more in the Western European countries relatively to the Eastern European countries over the last years (Pacyna, MSC/West, pers. comm.). It should be noticed that few countries in Southern- and Eastern Europe have reported data for heavy metals in precipitation.

Figure 1: Kriged map of lead in precipitation, 1997 (µg/l).

Cadmium in precipitation

In Scandinavia the annual mean values of Cd are below 0.10 µg Cd/l (Figure 2). An increasing gradient can be seen southward. The highest concentrations of Cd, above 0.20 µg Cd/l, are reported from GB91, BE4 and DE2. It should be noticed that only 4 3-monthly samples are reported from the UK stations. There are no data reported from Southern Europe (except Portugal with too high detection limit for Cd) and only the Czech Republic and the Baltic States have reported data from Eastern Europe. The emissions of Cd have also decreased in Europe in recent years, but not so much as for Pb (Pacyna, pers. comm.; Bartnicki, 1998).

Figure 2: Kriged map of cadmium in precipitation, 1997 (µg/l).

TEMPORAL TRENDS FOR LEAD IN AEROSOLS

Figure 3 shows temporal trends for lead in aerosols at 4 stations for which there have been reported data from for at least four years. Several countries in Europe have reduced their emissions of Pb which can be seen in the decreasing level in the Pb concentrations at DE4, DK3 and SK4. A marked seasonal variation in the level of Pb can be seen at NO42 with highest concentrations during the high Arctic winter.

Fig 3: Temporal trends for lead in aerosols