ICES BASE-LINE SURVEY OF TRACE-METALS IN EUROPEAN SHELF WATERS

Dissolved trace-metal (Cd. Cu. Pb, Zn, Hg) data held by ICES have been assessed and reviewed. Difficulties associated with sampling close to sources of known contamination, uncertainties over the quality of the sampling and analysis, and comparison of filtered and unfiltered samples complicated this assessment. For Cd and Cu. data of sufficient quantity and quality exist to describe adequately their distribution in coastal waters. The results are in good agreement with previously published data. For the other elements, notably Zn and Hg. there are less data and the interpretation is more difficult. Generally, however, the conclusions are in broad agreement with published results. The variability in the data limits the applicability of baseline datasets, such as the one described here, for monitoring changes in seawater concentrations of metals. An analysis of the magnitudes of the changes in concentrations that should be visible is presented. A temporal trend in the data is seen in only one of 50 possible year-to-year comparisons. © 1993 Conseil International pour l’Exploration de la Mer.