Superficial deep-water sediments of the Eastern Marmara Basin

Superficial sediments (top ∼ Im) of the Eastern Mediterranean Basin, Sea of Marmara, Turkey accumulated rapidly (0.087 ± 0.012 g/cm2 · y) by hemipelagic sedimentation with only limited amounts of gravity flow or bottom current action under low oxygenated but not anoxic conditions. They have restricted faunas, relatively higher organic carbon (1-1.8%) and lower calcium carbonate (14-20%) contents than other Eastern Mediterranean Basin sediments. Sedimentation shows little change over the last millenium except for an increase in Cu, Zn, Pb, Cr, and P over the last few centuries. The increase was most likely caused by increased metallurgical activities since the eighteenth century but are not at sufficient levels for the area to be regarded as polluted. © 1989 Springer-Verlag New York Inc

Sedimentation rates in the central lake constance determined with210Pb and137Cs

Sediment cores from central Lake Constance were dated with210Pb and137Cs. A sedimentation rate of (0.11±0.02) g·cm-2·y-1 was determined with the210Pb method.137Cs measurements revealed sedimentation rates of (0.11±0.01) g·cm-2·y-1 and (0.08±0.01) g·cm-2·y-1 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 the137Cs 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 from7Be measurements. © 1987 Birkhäuser Verlag

Beryllium-10: Half-life and AMS-standards

Absolute AMS measurements of /sup 10/Be require reliable standards for calibration. Among the existing standards, rather large differences have been observed. These differences were found partially to be due to the different half-life values which were assumed. Also for comparison of AMS data with activity measurements, it is necessary to know the /sup 10/Be half-life as precisely as possible. Starting with 5 ml of the standardized ORNL-MASTER solution, a working solution with a well-defined /sup 10/Be content was prepared. Its specific activity was determined by liquid scintillation counting. This measurement yielded a new value of (1.52 +- 0.05) My for the /sup 10/Be half-life, which is in agreement with the previously reported values but is about three times more accurate. Two independent dilution series produced new AMS standards with /sup 10/Be//sup 9/Be ratios of the order of 10/sup -10/ and 10/sup -11/. These standards were measured at the ETH/SIN AMS facility with high accuracy and are compared with other available /sup 10/Be standards. 15 refs, 2 figs., 3 tabs