Sediment focusing and210Pb dating: a new approach |
| |
| Authors: | D J Rowan R J Cornett K King B Risto |
| |
| Institution: | (1) Environmental Research Branch, Chalk River Laboratories, K0J 1J0 Chalk River, Ontario, Canada |
| |
| Abstract: | In this paper we test the utility of the mud deposition boundary depth (mud DBD) theory (Rowanet al. 1992) as a means of maximizing sampling efficiency in paleolimnological investigations, particularly those that apply to210Pb dating. The mud DBD is defined by the relationship between near bottom wave velocity and particle threshold velocity, with wave and particle threshold theory simplified to terms of exposure and depth. Mud DBD theory can be used to define the depositional zone in lakes, and within the depositional zone defined by the mud DBD: 1) there is a high probability of obtaining a representative core, 2) variation in mass sediment accumulation rate (MSAR) is not correlated with water depth, and 3) variation in MSAR is considerably reduced from the whole lake average. This suggests that mud DBD theory can account for the effects of sediment focusing, and that the mud DBD defined depositional zone is the zone to which fine-grained sediments are focused. Finally, we have shown that to optimize sampling effort, 5 to 10 cores within the depositional zone are necessary for a reasonably precise estimate of the mean mass sediment accumulation rate. In addition, the use of mud DBD theory prior to sampling can dramatically reduce the cost associated with analyzing large numbers of cores for210Pb.This is the fifth of a series of papers to be published by this journal following the 20
th
anniversary of the first application of210Pb dating of take sediments. Dr P. G. Appleby is guest editing this series. |
| |
| Keywords: | 210Pb sediments cores paleolimnology lakes sediment focusing sampling |
| 本文献已被 SpringerLink 等数据库收录！ |
|
