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Free keywords:
Beryllium-10 - Solar activity - Varved lake sediments - Climate - Lake Lehmilampi
DDC:
550 - Earth sciences
Abstract:
Annually resolved terrestrial 10Be archives other than those in polar ice sheets are heretofore unexplored sources of information about past solar activity and climate. Until now, it has proven difficult to find natural archives that have captured and retained a 10Be production signal, and that allow for annual sampling and contain sufficient 10Be for AMS measurement. We report the first annually resolved record of 10Be in varved lake sediments. The record comes from Lake Lehmilampi, eastern Finland, which lies at 63°37′N, 29°06′E, 95.8 m a.s.l. The focus on the last 100 years provided an unprecedented opportunity to compare sediment 10Be data with annual ice core, neutron monitor and sunspot number data. Results indicate successful recovery of 10Be atoms from as little as 20 mg sediment. Sediment 10Be accumulation rates suggest control by solar activity, manifested as a reflection of the 11-year Schwabe solar cycle and its amplitude variations throughout the investigated period. These results open the possibility of using varved lake sediment 10Be records as a new proxy for solar activity, thus providing a new approach for synchronization of paleoclimate events worldwide.
