CHERNOBYL CS-137 USED TO DETERMINE SEDIMENT ACCRETION RATES AT SELECTED NORTHERN EUROPEAN COASTAL WETLANDS

Sediment cores were collected from five coastal wetlands along the Nor th Sea (England and Netherlands) and Baltic Sea (Poland). Cs-137 datin g was used to assess sediment accretion rates, including rates based o n the Cs-137 peak from the 1986 accident at Chernobyl. Peaks from the Chernobyl fallout were found in cores from the Oder and Vistula Rivers in Poland, from the Eastern Scheldt in the Netherlands, and in one of the two cores from Stiffkey Marsh, U.K. No evidence of Chernobyl fall out was found in cores from Dengie Marsh, U.K. The Chernobyl Cs-137 pe ak serves as an excellent marker for short-term accretion rates becaus e of its high activity. Vertical accretion rates (cm yr(-1)) based on 1963 and 1986 peaks were similar at most sites; differences may be due to large inputs of sediment from storms or recent accumulation of org anic matter. Large differences in sediment characteristics and accreti on rates were found between samples from Poland and western Europe. Ve rtical accretion rates over the period 1963-1986 ranged from 0.26 to 0 .85 cm yr(-1) and from 0.30 to 1.90 cm yr(-1) over the 1986-1991 perio d. Vertical accretion rates for the period 1963-1991 were greater than the rates of relative sea-level rise for all cores, so it does not se em that any of these sites are in imminent danger of excessive floodin g. The Chernobyl Cs-137 peak will be especially useful for studies of short-term (i.e. very recent) sedimentation in the near future and for comparisons of sediment processes over different time scales.