Metal concentration in biota in the North sea: changes and causes

Abstract

The article reviews available information on time trends in metal concentration in biota from monitoring studies in the North Sea. Data collected in Danish marine waters are presented as examples of changes in metal concentrations since 1975. Causes of trends and problems associated with the use of measurements in biota when assessing time trends in metals are discussed. Although emissions of many metals have apparently been reduced during the last 15 years due to different regulations, it has only been possible to detect any significant changes in the environment in very few of the more contaminated coastal areas. It is argued that this might well be caused by the lack of understanding of the effects of biological covariables on metal concentrations which may explain part of the variance observed in samples, and also of the physical and biogeochemical processes, which may cause changes in the bioavailability of metals and levels of contamination.