Sedimentation rates in the central lake constance determined with210Pb and137Cs

Abstract

Sediment cores from central Lake Constance were dated with Zl~ and [37Cs. A sedimentation rate of(0.11 :t:0.02) g-cm-2.y -I was determined with the 21~ method. 137Cs measurements revealed sedimentation rates of (0.11+0.01) g.cm--~.y -t and (0.08:1:0.01) g.cm-2-y -I, respectively for two different cores sampled at the same location. The lower Cs-dated value indicates incomplete core recovery and demonstrates the sensitivity of this simple dating method to small losses of material at the water/sediment interface. An unambiguous application of the 137Cs method is, therefore, only possible if complete core recovery is ensured. Sedimentation rates based on particulate matter, collected in sediment traps at various water depths, agree with the results of the radioisotope methods. Estimates of 30-125 days residence times for suspended particulate matter were calculated from 7Be meausurements.

Large Lakes

“…This value comes quite close to the flux recorded in the sediment traps of 0.098 g/cm 2 yr and to the accumulation rate of 0.08-0.11 g/cm 2 yr in two cores from the central part of Lake Constance (von Gunten et al, 1987), where core recovery is assumed to be perfect. This value comes quite close to the flux recorded in the sediment traps of 0.098 g/cm 2 yr and to the accumulation rate of 0.08-0.11 g/cm 2 yr in two cores from the central part of Lake Constance (von Gunten et al, 1987), where core recovery is assumed to be perfect.…”

Radiochronology of lake sediments

“…The presence of 7Be in the sediments thus ensures complete core recovery. We have used the above mentioned radioisotopic techniques over the years for the dating of sediments fiom Lakes Zurich and Constance; the Sea of Marmara as well as sediments fiom southern Turkey and eastern Spain regions of the Mediterranean sea (3,4,5,6). EXPERIMENTAL Sediment cores were recovered using either a gravity corer with transparent PVC-tubes (inner diameter 6.3 cm) or a box cover (Sea of Marmara Sediments).…”

Radiochronology of sediments from the Mediterranean Sea using natural210Pb and fallout137Cs

“…5,6 In those studies the recovery of the topmost sediment seCtion was checked by measuring cosmic ray-produced 7Be (53 d) in first sediment sample. Observation of 7Be as in our case indicated no sediment loss.…”