Abstract:
Systematic Studies of sedimentation rate variations are essential for
interpretation of a variety of lake sediment interaction processes and also important in the
study of the kinetics of transfer between the lake sediment reservoirs. Mass accumulation
rates of minerals, but also organic debris, nutrient elements, and trace metals in sediments
and their temporal variations require accurate sedimentation rate measurements. Studies
of temporal variations in lacustrine sedimentation and the relation of such variations to
climatic and/or anthropogenically induced changes in lakes, require knowledge of
sedimentation rates and their temporal variations over time scale generally ranging from a
few years to tens of thousands of years.
Various methods have been adopted for estimation of rate of
sedimentation. In the latter part of the last century, the common technique used, in
estimation of sedimentation rate is based on the study of rapid rise of ragweed pollen
(Ambrosia) due to extensive forest cutting and soil cultivation by many (Bortleson and
Lee, 1972; Craig, 1972; Kemp et al., 1974; and Maher, 1977). However, the recent dating
techniques involve natural radio-isotope lead-210 estimation (ICrishnaswami et al., 1971;
Koide et al., 1973) and the bomb fallout nuclide Cesium-137 (Pennington et al., 1973).
The relatively short lived isotopes (22.3 years for Pb21° and 30 years for CS137 are ideally
suited for lake sediments whose rates of sedimentation are on the order of a few
millimeters per year (for details see Krishnaswami and La!, 1978).
