Radiocesium dating of sediments from lakes and reservoirs of different hydrological regimes
Important information on the transport and deposition of anthropogenic substances in rivers and lakes can be assessed using sediment analyses. Dating is a necessary prerequisite to calculate fluxes, to account for varying sedimentation rates, and thus to allow comparison between different localities. For sediments not older than 40 years, 137Cs dating has been successfully applied to natural and artificial lakes representing a wide range in water-residence times and sediment-trapping characteristics. Sedimentation rates for the period 1986 to the time of coring (mid 1990s) vary as a function of distance to the inflowing rivers, between 0.5 and 2.5 cm yr-1 (0.13−1.0 g cm-2 yr-1) in Greifensee and between 1.4 and 3.5 cm yr-1 (0.49−2.4 g cm-2 yr-1) in Lake Biel. In reservoirs located along the major Swiss rivers Aare and Rhine, sedimentation rates are in the same range from 1.8 cm yr-1 (0.69 g cm-2 yr-1) in Augst (Rhine) to 3.4 cm hr-1 (1.8 g cm-2 yr-1) in Klingnau (Aare). Sedimentation rates from the period...