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Multi-archive studies of climate events and archive-specific response times require synchronous time scales. Aligning common variations in the cosmogenic radionuclide production rate via curve fitting methods provides a tool for the continuous synchronization of natural environmental archives down to decadal precision. Based on this approach, we synchronize 10Be records from Western Gotland Basin (WGB, Baltic Sea) and Lake Kälksjön (KKJ, central Sweden) sediments to the 14C production time series from the IntCal20 calibration curve during the Mid-Holocene period ~6400 to 5200 a BP. Before the synchronization, we assess and reduce non-production variability in the 10Be records by using 10Be/9Be ratios and removing common variability with the TOC record from KKJ sediments based on regression analysis. The synchronizations to the IntCal20 14C production time scale suggest decadal to multi-decadal refinements of the WGB and KKJ chronologies. These refinements reduce the previously centennial chronological uncertainties of both archives to about ± 20 (WGB) and ±40 (KKJ) years. Combining proxy time series from the synchronized archives enables us to interpret a period of ventilation in the deep central Baltic Sea basins from ~6250 to 6000 a BP as possibly caused by inter-annual cooling reducing vertical water temperature gradients allowing deep water formation during exceptionally cold winters. [ABSTRACT FROM AUTHOR]

Northern Hemispheric high-latitude climate variations during the last glacial are expected to propagate globally in a complex way. Investigating the evolution of these variations requires a precise synchronization of the considered environmental archives. Aligning the globally common production rate variations of the cosmogenic radionuclide 10Be in different archives provides a tool for such synchronizations. Here, we present a 10Be record at <40-y resolution along with subdecadal proxy records from one Black Sea sediment core around Greenland Interstadial 10 (GI-10) ~41 ka BP and the Laschamp geomagnetic excursion. We synchronized our 10Be record to that from Greenland ice cores based on its globally common production rate variations. The synchronized environmental proxy records reveal a bipartite climate response in the Black Sea region at the onset of GI-10. First, in phase with Greenland warming, reduced sedimentary coastal ice rafted detritus contents indicate less severe winters. Second, and with a lag of 190 (± 44) y, an increase in the detrital K/Ti ratio and authigenic Ca precipitation point to enhanced regional precipitation and warmer lake surface temperatures. We explain the lagged climatic response by a shift in the dominant mode of atmospheric circulation, likely connected with a time-transgressive adjustment of the regional thermal ocean interior to interstadial conditions. [ABSTRACT FROM AUTHOR]

Sediment microfacies, geochemical μ‐XRF and X‐ray density analyses were conducted on varved sediments from Lake Kortejärvi (eastern Finland) covering the last 2700 years. The varves comprise couplets of detrital and organic sub‐layers throughout the complete time‐span. Based on their microfacies and stratigraphical position within a varve as well as comparisons with local discharge and meteorological data, thicker detrital layers are interpreted to reflect intensified snow‐melt floods following more humid winters. Detailed comparisons with monthly to annually resolved North Atlantic Oscillation (NAO) indices back to AD 1049 (901 a BP) suggest that multidecadal increases in snow‐melt layer thickness tend to be connected with a more positive phase of the NAO and, consequently, warmer winters. In contrast, distinct centennial intervals of thicker snow‐melt layers from −40 to 170, 280 to 460 and 1900 to 2300 a BP as well as around 2600 a BP do not consistently correspond to a particular NAO phase, but coincide with extended sea‐ice margins and a colder North Atlantic climate, causing intensified and southward shifted westerly cyclones. Our results point to a differential modification of North Atlantic winter hydroclimate working on varying time scales. [ABSTRACT FROM AUTHOR]

[Display omitted] • Radionuclides and models show soil erosion dynamics over decades to century. • Soil-erosion trend is increasing over past decades on the southeastern TP. • Increasing temperature and human activities are main triggers of recent soil erosion. • Accelerating soil erosion is particularly strong for permafrost-dominant regions. Soil erosion has created landscape problems in many parts of the world and in particular in cold regions where the sensitive permafrost conditions have changed due to climate warming. Such a case occurred in the Tibetan Plateau (TP), which has been strongly affected by global warming and human activities. Monitoring technologies, like remote sensing and field surveys were used to explore soil erosion rates in the TP, but they were limited by the resolution and meteorological disturbance factors or the spatial and time scales. Here, we present for the first time 210Pb ex (excess lead-210) and 137Cs (caesium-137) data of soils from the southeastern TP (SETP) covering an area of 640,000 km2. In the permafrost-dominant areas, the results show mean soil-erosion rates in the last 56–100 years that were relatively higher (1891 t·km−2·a-1) based on 210Pb ex than those based on 137Cs (1623 t·km−2·a-1). Modelling results from the Revised Universal Soil Loss Equation (RUSLE) indicate relatively high mean soil erosion rates of 4363 and 4394 t·km−2·a-1 using a period covering the last 40 or 10 years respectively. Our data suggest accelerating erosion rates on the SETP that are linked to permafrost degradation, and glacier and snow melting due to accelerating global climate warming. The increase in ground surface temperature of ∼2 °C in the last four decades has further shifted the regional hydrology, affecting the degeneration of vegetation cover and a further increase in soil-erosion rates. However, our radionuclides data also expose low erosion rates in the seasonally frozen ground at some sampling sites which indicates the complex nature of erosion trends in cold regions that require careful adaptation of soil management. [ABSTRACT FROM AUTHOR]

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]

The marine-terrestrial Baltic ecosystem is sensitive to a range of environmental forcing and thresholds. Multi-archive investigations of its evolution require a precise synchronization of the considered archives. Here, we apply globally common cosmogenic radionuclide production rate variations to synchronize 10Be records from brackish Western Gotland Basin (Baltic Sea) and terrestrial lake Tiefer See (NE Germany) sediments to the atmospheric 14C time-scale and investigate phase-relationships in proxy responses in the southern Baltic realm associated with the onset of a centennial Mid-Holocene climate oscillation ∼5800 a BP. Based on paired molybdenum and titanium records, we identify a 98 ± 81-year delay in Western Gotland Basin ventilation, compared to the terrestrial response at the onset of the recorded Mid-Holocene climate oscillation. Most plausible mechanism for this delay is strengthened stratification in response to enhanced freshwater input during the first decades of the oscillation. • 10Be used for synchronizing Baltic Sea and terrestrial lake sediment records. • Synchronous southern Baltic sediment records of environmental variability. • Subcentennial delay in Western Gotland Basin ventilation during the Mid-Holocene. [ABSTRACT FROM AUTHOR]

Abstract: Microfacies analyses and X-ray fluorescence scanning (μ-XRF) at sub-mm resolution were conducted on the varved Mid- to Late Holocene interval of two sediment profiles from pre-alpine Lake Ammersee (southern Germany). The coring sites are located in a proximal (AS10prox) and distal (AS10dist) position towards the main tributary River Ammer, in 1.8 km distance from each other. To shed light on sediment distribution within the lake, particular emphasis was (1) the detection of intercalated detrital layers and their micro-sedimentological features, and (2) intra-basin correlation of these event deposits. Detrital layers were dated by microscopic varve counting, verified by accelerator mass spectrometry 14C dating of terrestrial plant macrofossils. Since ∼5500 varve years (vyr) BP, in total 1573 detrital layers were detected in either one or both of the investigated sediment profiles. Based on their microfacies, geochemistry, and proximal-distal deposition pattern, detrital layers were interpreted as River Ammer flood deposits. Earlier studies on flood layer seasonality have proven that flood layer deposition occurs predominantly during spring and summer, the flood season at Lake Ammersee. Most prominent features of the record are the onset of regular flood layer deposition at ∼5500 vyr BP in AS10prox and ∼2800 vyr BP in AS10dist as well as three major increases in mean flood layer thickness at ∼5500, 2800, and 400 vyr BP. Integrating information from both sediment profiles allowed to interpret these changes in terms of shifts towards higher mean flood intensity. Proposed triggering mechanisms are gradual reduction in Northern Hemisphere orbital summer forcing and superimposed centennial-scale solar activity minima. Likely responses to this forcing are enhanced equator-to-pole temperature gradients and changes in synoptic-scale atmospheric circulation. The consequences for the Ammersee region are more intense cyclones leading to extremer rainfall and flood events in spring and summer. [Copyright &y& Elsevier]

Annually laminated sediments of Lake Woserin in north-eastern Germany are investigated using sedimentological and palynological methods. They facilitate high-resolution reconstruction of environmental and land-use change during ca. 7000-4000 cal. BP. Between 6100 and 5800 cal. BP, changes in woodland composition and structure are evident which coincide with a change in subsistence strategy, that is, the adoption of animal husbandry. For the remaining period, eight phases of enhanced human impact (5750-5390, 5270-5150, 4890-4750, 4670-4600, 4520-4450, 4390-4350, 4250-4170 and 4070-3930 cal. BP) are identified. Hereby, the first phase relates to an opening of the landscape in connection with the adoption of large-scale, extensive cereal cultivation. Phases of decreased human impact are generally characterised by woodland regeneration. Over-regional comparison of the results reveals similar and synchronous fluctuation of human impact in the young moraine area of the south-western Baltic region and hints at a large-scale driver. In order to evaluate the role of environmental change for human activity, evidence for coinciding shifts in palaeoclimate records and their potential implication for human-environment interactions are discussed and generally support the idea that environmental changes played an important role for the cultural development during the Neolithic in Northern Germany. Hereby, climate change probably favoured the adoption of new subsistence strategies during the early Neolithic (6100-5350 cal. BP). Furthermore, the fluctuating human impact during Middle and Younger Neolithic (5350-4100 cal. BP) could indicate a socio-economic system susceptible for short-termed climatic fluctuation. [ABSTRACT FROM AUTHOR]

The precipitation rate dominates meteoric 10Be in soils rather than soil dynamics, and the relation of the two is indicated in a binomial way with positive correlation in low precipitation regions (<1200 mm per year) and negative in high precipitation regions (>1200 mm per year). • 10Be concentrations in topsoil are influenced by precipitation and soil dynamics. • Precipitation shows more control on 10Be using PCA and correlation analysis. • 10Be concentrations-precipitation shows different trends in dry and humid regions. • Underlying surface affects 10Be without changing 10Be-precipitation relationships. Meteoric beryllium-10 (10Be) is commonly used as a proxy of landscape dynamics (erosion and sedimentation rates) and soil development. Soil represents the first-stage reservoir of meteoric 10Be, and variability in the concentration of the isotope in soils may be affected by soil properties and atmospheric deposition. Although many investigations have targeted this issue, there are still problems in estimating the atmospheric input of the isotope in different soil environments. Here, we used 10Be data measured in soils distributed across China to explore the potential influence of meteorological and pedological conditions on the isotope concentration and related applications. In addition, to determine the mechanisms controlling 10Be concentrations in topsoil on a regional scale, the soil samples were sub-divided into 18 different catchments according to fluvial systems. The results indicated that there were significant negative correlations between precipitation and the soil 10Be concentration in high-precipitation regions (>1200 mm·y−1) and significant positive correlations for soils in low precipitation regions (<1200 mm·y−1). The data also revealed that precipitation is the most important variable controlling the 10Be concentration in soils of China when compared with the effects of soil properties such as grain size, mineralogy, pH, and cation exchange capacity. Land use and soil erosion may have limited impacts on the distribution of 10Be in soils. [ABSTRACT FROM AUTHOR]

Si fluxes from the continents to the ocean are a key element of the global Si cycle. Due to the ability of coastal ecosystems to process and retain Si, the 'coastal filter' has the potential to alter Si fluxes at a global scale. Coastal zones are diverse systems, sensitive to local environmental changes, where Si cycling is currently poorly understood. Here, we present the first palaeoenvironmental study of estuarine biogenic silica (BSi) fluxes and silicon isotope ratios in diatoms (δ30Sidiatom) using hand-picked diatom frustules in two sediment cores (CBdist and CBprox) from the Chesapeake Bay covering the last 12000 and 8000 years, respectively. Constrained by the well-understood Holocene evolution of the Chesapeake Bay, we interpret variations in Si cycling in the context of local climate, vegetation and land use changes. δ30Sidiatom varies between + 0.8 and + 1.7‰ in both sediment cores. A Si mass balance for the Chesapeake Bay suggests much higher rates of Si retention (~ 90%) within the system than seen in other coastal systems. BSi fluxes for both sediment cores co-vary with periods of sea level rise (between 9500 and 7500 a BP) and enhanced erosion due to deforestation (between 250 and 50 a BP). However, differences in δ30Sidiatom and BSi flux between the sites emphasize the importance of the seawater/freshwater mixing ratios and locally variable Si inputs from the catchment. Further, we interpret variations in δ30Sidiatom and the increase in BSi fluxes observed since European settlement (~ 250 a BP) to reflect a growing human influence on the Si cycle in the Chesapeake Bay. Thereby, land use change, especially deforestation, in the catchment is likely the major mechanism. [ABSTRACT FROM AUTHOR]

Abstract: Tephrochronological studies of partly varved sediments of Trzechowskie palaeolake in central Northern Poland led to the finding of the Late Allerød Laacher See Tephra (LST) from the Eifel Volcanic Field for the first time in a very distal site ca 840 km ENE from its volcanic source. The detection of glass shards of the LST involved a comprehensive combination of techniques, i.e. biostratigraphical constrains, high-resolution μ-XRF core scanning and areal μ-XRF mapping of impregnated sediment slabs as well as detailed visual inspection of sediments. The major element chemistry of volcanic glass confirmed the Laacher See Tephra composition in Trzechowskie palaeolake sediments suggesting a deposition from the Middle Laacher See Tephra (MLST-C) or Upper Laacher See Tephra (ULST) dispersal fans. The finding of the LST in this palaeolake enables direct synchronisation with other high-resolution archives in north-central Europe (i.e., Lake Meerfelder Maar, Rehwiese palaeolake) to investigate regional variations of environmental responses at the onset of the Younger Dryas along a West-East transect through north-central Europe. [Copyright &y& Elsevier]

The continental silicon (Si) cycle, including terrestrial and freshwater ecosystems (lakes, rivers, estuaries), acts as a filter and modulates the amount of Si transported to the oceans. In order to link the variation in the terrestrial Si cycle to aquatic ecosystems, knowledge on changes in vegetation cover, soil disturbance and the impact of human activity are required. This study on varved lake sediments from Tiefer See near Klocksin (TSK) in northeastern Germany investigates Si isotope variations in diatom frustules (δ30Si diatom) over the last ∼4300 years. δ30Si diatom values vary between 0.37 and 1.63‰. The isotopic signal measured in centric (mostly planktonic) and pennate (mostly benthic) diatoms shows the same trend through most of the record. A decrease in δ30Si diatom coinciding with early deforestation between 3900 and 750 a BP in the catchment area, points to an enhanced export of isotopically light dissolved silica (DSi) from adjacent soils to the lake. The burial flux of biogenic silica (BSi) observed in the lake sediments increases with cultivation due to enhanced nutrient supply (N, P and Si) from the watershed and nutrient redistribution caused by wind-driven increased water circulation. When the cultivation intensifies, we observe a shift to higher δ30Si diatom values that we interpret to reflect a diminished Si soil pool and the preferential removal of the lighter 28Si by crop harvesting. Human activity influences the DSi supply from the catchment and appears to be the primary driver controlling the Si budget in TSK. Our data shows how land use triggers variations in continental Si cycling on centennial timescales and provides important information on the underlying processes. • Study of Si isotopes and BSi from lake sediments during the last 4300 years. • DSi fluxes are the main control on Si cycling in Tiefer See. • Vegetation changes and landscape cultivation alter Si fluxes. • Crop harvest reduces Si availability in the catchment. [ABSTRACT FROM AUTHOR]

In the initial online version of the article, the final term in the second equation in the "Materials and methods" section was incorrectly shown as 100 instead of 1000. The original article has been corrected. [ABSTRACT FROM AUTHOR]