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Solar modulated variations in cosmogenic radionuclide production provide both information on past changes in the activity of the Sun and a global synchronization tool. However, to date the use of cosmogenic radionuclides for these applications is almost exclusively based on 10 Be records from ice cores and 14 C time-series from tree rings, all including archive-specific limitations. We present the first 10 Be record from annually laminated (varved) lake sediments for the Lateglacial-Holocene transition from Meerfelder Maar. We quantify environmental influences on the catchment and, consequently, 10 Be deposition using a new approach based on regression analyses between our 10 Be record and environmental proxy time-series from the same archive. Our analyses suggest that environmental influences contribute to up to 37% of the variability in our 10 Be record, but cannot be the main explanation for major 10 Be excursions. Corrected for these environmental influences, our 10 Be record is interpreted to dominantly reflect changes in solar modulated cosmogenic radionuclide production. The preservation of a solar production signal in 10 Be from varved lake sediments highlights the largely unexplored potential of these archives for solar activity reconstruction, as global synchronization tool and, thus, for more robust paleoclimate studies. [ABSTRACT FROM AUTHOR]

Time-series of varve properties and geochemistry were established from varved sediments of Lake Woserin (north-eastern Germany) covering the recent period AD 2010-1923 and the mid-Holocene time-window 6400-4950 varve years before present (vyr BP) using microfacies analyses, x-ray fluorescence (µ-XRF) scanning, microscopic varve chronology, and 14C dating. The microscopic varve chronology was compared with a macroscopic varve chronology for the same sediment interval. Calcite layer thickness during the recent period is significantly correlated to increases in local annual precipitation (r = 0.46, p = 0.03) and reduced air-pressure (r = -0.72, p < 0.0001). Meteorologically consistent with enhanced precipitation at Lake Woserin, a composite 500 hPa anomaly map for years with >1 standard deviation calcite layer thickness depicts a negative wave train air-pressure anomaly centered over southern Europe, with north-eastern Germany at its northern frontal zone. Three centennial-scale intervals of thicker calcite layers around the mid-Holocene periods 6200-5900, 5750-5400, and 5300-4950 vyr BP might reflect humid conditions favoring calcite precipitation through the transport of Ca2+ ions into Lake Woserin, synchronous to wetter conditions in Europe. Calcite layer thickness oscillations of about 88 and 208 years resemble the solar Gleissberg and Suess cycles suggesting that the recorded hydroclimate changes in north-eastern Germany are modified by solar influences on synoptic-scale atmospheric circulation. However, parts of the periods of thicker calcite layers around 5750-5400 and 5200 vyr BP also coincide with enhanced human catchment activity at Lake Woserin. Therefore, calcite precipitation during these time-windows might have further been favored by anthropogenic deforestation mobilizing Ca2+ ions and/or lake eutrophication. [ABSTRACT FROM AUTHOR]

Beryllium 10 concentrations ( 10 Be con ) were measured at annual resolution from varved sediment cores of Lakes Tiefer See (TSK) and Czechowskie (JC) for the period 1983–2009 (∼solar cycles 22 and 23). Calibrating the 10 Be con time-series against complementing proxy records from the same archive as well as local precipitation and neutron monitor data, reflecting solar forced changes in atmospheric radionuclide production, allowed (i) identifying the main depositional processes and (ii) evaluating the potential for solar activity reconstruction. 10 Be con in TSK and JC sediments are significantly correlated to varying neutron monitor counts (TSK: r = 0.5 , p = 0.05 , n = 16 ; JC: r = 0.46 , p = 0.03 , n = 22 ). However, the further correlations with changes in organic carbon contents in TSK as well as varying organic carbon and detrital matter contents in JC point to catchment specific biases in the 10 Be con time-series. In an attempt to correct for these biases multiple regression analysis was applied to extract an atmospheric 10 Be production signal ( 10 Be atmosphere ). To increase the signal to noise ratio a 10 Be composite record ( 10 Be composite ) was calculated from the TSK and JC 10 Be atmosphere time-series. 10 Be composite is significantly correlated to variations in the neutron monitor record ( r = 0.49 , p = 0.01 , n = 25 ) and matches the expected amplitude changes in 10 Be production between solar cycle minima and maxima. This calibration study on 10 Be from two sites indicates the large potential but also, partly site-specific, limitations of 10 Be in varved lake sediments for solar activity reconstruction. [ABSTRACT FROM AUTHOR]