Determination of Depositional Beryllium-10 Fluxes in the Area of the Laptev Sea and Beryllium-10 Concentrations in Water Samples of High Northern Latitudes

Abstract

Present day accumulation rates of nine sediment cores recovered during the Russian-German Expedition Transdrift II (1994) from the shelf area of the Laptev Sea were determined by 210Pbex dating and vary from 0.05 to 0.24 g cm-2 a-1. In addition, the sedimentation rates during the isotopic stages 2, 3 and 5 of the sediment core PS 2471-4 from the continental slope of the Laptev Sea were determined via 230Thex dating. The 10Be concentrations together with the accumulation rates (or sedimentation rates) yield the depositional 10Be fluxes in the shelf area of [(10–150) • 106 at cm-2 a-1] and of [(0.9–4.1) • 106 at cm-2 a-1] on the continental slope from the Laptev Sea. They are clearly higher than the recent atmospheric input determined in Greenland ice cores [(0.2–0.5) • 106 at cm-2 a-1]. We conclude that large amounts of continental 10Be are delivered to the Laptev Sea through the rivers (e.g. Lena, Yana) and that the major fraction of 10Be is deposited directly in the shelf area. The distinctly higher concentrations of 10Be in water samples from the shelf area of the Laptev Sea [1000 to 6000 at/g] compared to the concentrations measured in the Norwegian and Greenland Sea [300 to 1000 at/g] and the Central Arctic Ocean [500 at/g] are further evidence that rivers are an important source for the input of 10Be from the Siberian hinterland to the Arctic Ocean.