Heavy metal chronologies in selected coastal wetlands from northern Europe

Sediment cores were collected from five coastal wetlands in England, the Netherlands, and Poland, and samples analysed for heavy metal concentrations. Depth profiles of metal concentrations were converted to time-based profiles, using vertical accretion rates obtained from 137Cs dating. Chronologies of metal concentrations from the two cores (high and low marsh) at each site showed good agreement, indicating that sediment profiles represent historical inputs of metals. Sediment metal concentrations showed that some of the areas are highly polluted, with peak sediment concentrations up to five times greater than in the oldest sediment samples (1890s to 1900s). Chronologies indicated different pollution histories for the five areas. Local hydrology appeared to be important in affecting metal accumulation. Metal concentrations have recently decreased in the cores from St. Annaland Marsh (the Netherlands) and Stiffkey Marsh (UK). Levels of metals from the Oder River remained high throughout the upper part of the cores.