Sediment Accumulation Rates in an Alaskan Arctic Lake Using a Modified 210Pb Technique

Abstract

Because of high concentrations of authigenic Mn and Fe oxides in surficial sediments from Toolik Lake, Alaska, the normalization of depth and ²¹⁰Pb activity scales to the sediment Al content was used for sediment accumulation rate calculations. These results are compared with the conventional ²¹⁰Pb dating technique. I found the flux of ²¹⁰Pb to the lake to be very low (10 dpm∙cm⁻²∙yr⁻¹), and excess ²¹⁰Pb is restricted to the top 5 cm of sediment. The whole lake sediment accumulation rate is about 2.7 mg∙cm⁻²∙yr⁻¹ and the sediments are little disturbed by physical or biological processes. Low rates of physical and chemical weathering are responsible for the low sediment accumulation rates.