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Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal re-cords from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (similar to 9e6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

International audience; Severe extratropical winter storms are a recurrent feature of the European climate and cause widespread socioeconomic losses. Due to insufficient long-term data, it remains unclear whether storminess has shown a notable response to changes in external forcing over the past millennia, which impacts our ability to project future storminess in a changing climate. Reconstructing past storm variability is essential to improving our understanding of storms on these longer, missing timescales. Peat sequences from coastal ombrotrophic bogs are increasingly used for this purpose, where greater quantities of coarser grained beach sand are deposited by strong winds during storm events. Moving inland however, storm intensity decreases, as does sand availability, muting potential paleostorm signals in bogs. We circumvent these issues by taking the innovative approach of using mid-infrared (MIR) spectral data, supported by elemental information, from the inorganic fraction of Store Mosse Dune South (SMDS), a 5000-year-old sequence from a large peatland located in southern Sweden. We infer past changes in mineral composition and thereby, the grain size of the deposited material. The record is dominated by quartz, whose coarse nature was confirmed through analyses of potential local source sediments. This was supported by further mineralogical and elemental proxies of atmospheric input. Comparison of SMDS with within-bog and regionally relevant records showed that there is a difference in proxy and site response to what should be similar timing in shifts in storminess over the ~100 km transect considered. We suggest the construction of regional storm stacks, built here by applying changepoint modelling to four transect sites jointly. This modelling approach has the effect of reinforcing signals in common while reducing the influence of random noise. The resulting Southern Sweden-Storm Stack dates stormier periods to 4495e4290, 3880e3790, 2885e2855, 2300e2005, 1175e1065 and 715-425 cal yr BP. By comparing with a newly constructed Western Scotland-Storm Stack and proximal dune records, we argue that regional storm stacks allow us to better compare past storminess over wider areas, gauge storm track movements and by extension, increase our understanding of the drivers of storminess on centennial to millennial timescales.

Glacial Lake Outburst Floods (GLOFs) constitute a major hazard in glacierized regions. They are particularly pronounced in the Baker River watershed (Chilean Patagonia, 48 degrees S), where 23 events occurred between 2008 and 2020. Although GLOF deposits have previously been studied in lake settings, how modern GLOFs are recorded in fjord sediments remains mostly unknown. To address this issue, ten sediment cores collected in the fjord immediately downstream of the Baker River (Martinez Channel) were investigated and compared to the recent GLOF history of the river. Results show that sediments accumulate at 2.0 to 3.4 cm year(-1) and that GLOF deposits can be distinguished from background sediments by their finer grain size (5.98 +/- 0.82 mu m) and lower organic carbon content (0.31 +/- 0.06%), reflecting the release and transport in suspension of high amounts of glacial rock flour during GLOFs. Although 21 GLOFs from Cachet 2 Lake occurred between 2008 and 2017, the first events left a stronger imprint in the sediment, suggesting that more sediment of glacial origin was released during those initial events, possibly due to lake-bed erosion. An older GLOF deposit was tentatively linked to the outburst of Las Lengas Lake in 1988. The sediment cores also contain fine-grained turbidites, especially in the prodelta area. These turbidites confirm recent channel activity, but most of them seem to have been triggered by processes other than GLOFs. Overall, the results of this study suggest that GLOF deposits are distinct from typical flood turbidites. They are best identified by their low grain size and total organic carbon content, and best archived on the delta slope, away from any submarine channel influence. Finally, these results highlight the potential of fjord sediment archives to establish pre-historical GLOF records and ultimately improve GLOF hazard assessments.

The exact spatial and temporal behaviour of rapid climate shifts during the Last Glacial–Interglacial Transition are still not entirely understood. In order to investigate these events, it is necessary to have detailed palaeoenvironmental reconstructions at geographically spread study sites combined with reliable correlations between them. Tephrochronology, i.e., using volcanic ash deposits in geological archives as a dating and correlation tool, offers opportunities to examine the timing of events across wider regional scales. This study aims to review the posited asynchrony of the Younger Dryas stadial in comparison with Greenland Stadial-1 by correlating new proxy data from southernmost Sweden to previous palaeoclimate reconstructions in Europe based on the presence of the Hässeldalen Tephra, the Vedde Ash, and the Laacher See Tephra. μ-XRF core-scanning data were projected using a recently published age–depth model based on these tephras and several radiocarbon dates, and compared to previous findings, including by adapting previous chronologies to the recently proposed earlier date of the Laacher See Tephra (13,006 ± 9 cal. a BP). Although the results to some extent support the idea of a more synchronous Younger Dryas event than previously assumed, this issue requires further high-resolution proxy studies to overcome limitations of temporal precision.

Using diatoms, pollen, and geochemistry, we explore human habitation around Lina myr, Gotland, in relation to shore displacement. Archeological evidence has shown that Lina myr was an important area for its prehistoric human inhabitants. We investigate if and when Lina myr was connected to the sea and could therefore have been part of an inland water system useful for transport. A chronology was based on14C AMS dating of terrestrial macrofossils and bulk sediments with dates ranging between 9100 and 2360 cal. yr BP. The initiation of the Littorina transgression was dated to 8500 cal. yr BP. A twofold pattern for the maximum sub-phase of the Littorina Sea is suggested from 8100 to 7500 cal. yr BP and from 6500 to 6000 cal. yr BP. The onset of cultivation and grazing was indicated by the presence of Hordeum and Plantago lanceolata in the pollen record during the Late Neolithic, at about 4580 cal. yr BP. During this time sea level was relatively higher than today and the Lina myr basin was connected with the Littorina Sea, which it continued to be until isostatic uplift caused it to become isolated at about 3820 cal. yr BP. After about 3000 cal. yr BP, human-made landscape changes intensified, grasslands increased, and shrublands decreased.

Ombrotrophic peatlands are a globally important carbon store and depend on atmospheric nutrient deposition to balance ecosystem productivity and microbial decomposition. Human activities have increased atmospheric nutrient fluxes, but the impacts of variability in phosphorus supply on carbon sequestration in ombrotrophic peatlands are unclear. Here, we synthesise phosphorus, nitrogen and carbon stoichiometric data in the surface and deeper layers of mid-latitude Sphagnum-dominated peatlands across Europe, North America and Chile. We find that long-term elevated phosphorus deposition and accumulation strongly correlate with increased organic matter decomposition and lower carbon accumulation in the catotelm. This contrasts with literature that finds short-term increases in phosphorus supply stimulates rapid carbon accumulation, suggesting phosphorus deposition imposes a threshold effect on net ecosystem productivity and carbon burial. We suggest phosphorus supply is an important, but overlooked, factor governing long-term carbon storage in ombrotrophic peatlands, raising the prospect that post-industrial phosphorus deposition may degrade this carbon sink.

This article belongs to the Section Crystallography and Physical Chemistry of Minerals & Nanominerals., The mineral content of peat has received little attention until the last few decades, when peat cores have been increasingly used to study past dust deposition. Paleodust deposition is commonly reconstructed through elemental datasets, which are used to infer deposition rates, storminess patterns, mineral composition, source identification, and fertilization effects. To date, only a few studies have directly analyzed the mineralogy (by XRD and SEM) and particle size of peat mineral matter, and the conducted studies have usually been constrained by the need to remove a large amount of organic matter, which risks altering the mineral component. One alternative is to use quick, nondestructive techniques, such as FTIR-ATR, that require little sample preparation. In this study, we analyzed by FTIR-ATR both the bulk peat and ash fractions of a sequence taken in a minerogenic mire that covered a wide inorganic matter content range (6%–57%). Aided by principal component analysis on transposed IR spectral data, we were able to identify the main minerals in bulk peat and ash, quartz, mica (likely muscovite), K feldspar (likely microcline), and plagioclase (likely anorthite), which are consistent with the local geology of the mire catchment. Changes in mineral composition during the last ca. 2800 years were coeval with previously reconstructed environmental changes using the same core. Our results suggest that FTIR-ATR has great potential to investigate peat mineral matter and the processes that drive its compositional change., This research was funded by the grant Grupos de Referencia Competitiva (ED431C 2021/32) of Xunta de Galicia. L.L.M was supported by the Madrid Talent Attraction Program (Programa de Atracción de Talento de la Comunidad de Madrid, modalidad 1, 2019-T1/AMB-12782).

Severe winter windstorms have become an increasingly common occurrence over recent decades in northwestern Europe. Although there exists considerable uncertainty, storminess is projected to increas ...

Store Mosse (the ‘Great Bog’ in Swedish) is one of the most extensive bog complexes in southern Sweden (~77 km2), where pioneering palaeoenvironmental research has been carried out since the early 20th century. This includes, for example, vegetation changes, carbon and nitrogen dynamics, peat decomposition, atmospheric metal pollution, mineral dust deposition, dendrochronology, and tephrochronology. Even though organic matter (OM) represents the bulk of the peat mass and its compositional change has the potential to provide crucial ecological information on bog responses to environmental factors, peat OM molecular composition has not been addressed in detail. Here, a 568-cm-deep peat sequence was studied at high resolution, by attenuated reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) in the mid-infrared region (4000–400 cm–1). Principal components analysis was performed on selected absorbances and change-point modelling was applied to the records to determine the timing of changes. Four components accounted for peat composition: (i) depletion/accumulation of labile (i.e. carbohydrates) and recalcitrant (i.e. lignin and other aromatics, aliphatics, organic acids and some N compounds) compounds, due to peat decomposition; (ii) variations in N compounds and carbohydrates; (iii) residual variation of lignin and organic acids; and (iv) residual variation of aliphatic structures. Peat decomposition showed two main patterns: a long-term trend highly correlated to peat age (r = 0.87), and a short-term trend, which showed five main phases of increased decomposition (at ~8.4–8.1, ~7.0–5.6, ~3.5–3.1, ~2.7–2.1 and ~1.6–1.3 ka) – mostly corresponding to drier climate and its effect on bog hydrology. The high peat accumulation event (~5.6–3.9 ka), described in earlier studies, is characterized by the lowest degree of peat decomposition of the whole record. Given that FTIR-ATR is a quick, non-destructive, cost-effective technique, our results indicate that it can be applied in a systematic way (including multicore studies) to peat research and provide relevant information on the evolution of peatlands This research has been partially funded by Consiliencia network (ED 431D2017/08) Xunta de Galicia, GPC (ED431B 2018/20) Xunta de Galicia SI

Southern Africa sits at the junction of tropical and temperate systems, leading to the formation of seasonal precipitation zones. Understanding late Quaternary paleoclimatic change in this vulnerable region is hampered by a lack of available, reliably-dated records. Here we present a sequence from a well-stratified sedimentary infill occupying a lower slope basin which covers 17,060 to 13,400 cal yr BP with the aim to reconstruct paleoclimatic variability in the high Drakensberg during the Late Glacial. We use a combination of pollen, total organic carbon and nitrogen, δ13C, Fourier transform infrared spectroscopy attenuated total reflectance (FTIR-ATR) spectral and elemental data on contiguous samples with high temporal resolution (10 to 80 years per sample). Our data support a relatively humid environment with considerable cold season precipitation during what might have been the final stage of niche-glaciation on the adjoining southern aspects around 17,000 cal yr BP. Then, after an initial warmer and drier period starting ~15,600 cal yr BP, we identify a return to colder and drier conditions with more winter precipitation starting ~14,380 cal yr BP, which represents the first local evidence for the Antarctic Cold Reversal (ACR) in this region. On decadal to centennial timescales, the Late Glacial period was one marked by considerable climatic fluctuation and bi-directional environmental change, which has not been identified in previous studies for this region. Our study shows complex changes in both moisture and thermal conditions providing a more nuanced picture of the Late Glacial for the high Drakensburg.

The El Niño-Southern Oscillation (ENSO) is a driver of global atmosphere-ocean dynamics, but projections of frequency and magnitude in different climate states remain uncertain. Palaeoclimate records offer the potential to improve our understanding of ENSO behaviour but most are fragmentary, suffer low resolution, and/or typically do not cover periods warmer than present day. The Last Interglacial (129-116 kyr BP) was the most recent period during which global temperatures were close to 21st century projections, and potentially provides insights into operation of climate modes of variability in the future. Here we report a continuous, inter-annually resolved record of hydroclimate spanning 220-80 ka from Lynch’s Crater in tropical northeast Australia, a region highly sensitive to ENSO. Our reconstruction is based on a micro-X-ray fluorescence (XRF)-generated elemental profile at 200 µm resolution, combined with loss-on-ignition, magnetic susceptibility, and pollen analysis. We find that during globally warmer periods (including super-interglacial Stage 5e, and 5c), there are significantly larger amplitudes in high-frequency ENSO spectral range (3-8 years), which are absent from the record during the glacial stages MIS6 and MIS4. Our results imply an ENSO dependence on mean climate, with enhanced ENSO variance during interglacials globally warmer than present. These results are consistent with climate model projections for a future slowdown of the Walker circulation and more extreme El Niño events under greenhouse warming.

We present a high-resolution peat paleodust and accumulation rate record spanning the last 8300 years from Draftinge Mosse (400 ha), southern Sweden (57 degrees 06'27.6 '' N 13 degrees 42'54.1 '' E). The record was analysed for peat accumulation rates (PAR), elemental concentrations, mineralogy, and plant macrofossil content. Five periods of increased mineral deposition were recorded. The first event occurred between similar to 6280 and similar to 5570 cal BP, during the fen to bog transition. This is followed by four atmospheric mineral dust events (DE) which were recorded in the ombrotrophic section of the sequence at (cal BP): similar to 2200; similar to 1385-1150; similar to 830-590, and from similar to 420 to the present. Statistical analysis and elemental ratios indicated that both the mineralogy and grain size shifted when the system transitioned from fen into bog, showing that the governing transport process shifted with the peat-land succession stages. This highlights the importance of identifying peatland succession stages within peat paleodust studies. Following all four DE, increases in PAR were observed, implying a coupling to dust deposition. Comparison of DE and PAR with a paleodust record from Store Mosse, a 20 times larger bog located ca 18 km away (Kylander et al. 2016), showed that both PAR and dust deposition are largely represented by single-core reconstructions, indicating that they are driven by a common climate forcing mechanism. However, higher PAR and dust deposition rates were observed in the more moderately sized Draftinge Mosse, suggesting that the size of the bog is important to consider in peat paleodust studies. Furthermore, the smaller bog responded more rapidly to hydrological changes, indicating that the size of the bog affects its' buffering capacity. Authigenic carbonates, observed here during episodes of rapid peat growth, coincide with changes in REE ratios, indicating that authigenic peat processes potentially cause REE fractionation.

Atmospheric metal pollution is a major health concern whose roots pre-date industrialization. This study pertains the analyses of ancient human skeletons and compares them with natural archives to trace historical environmental exposure at the edge of the Roman Empire in NW Iberia. The novelty of our approach relies on the combination of mercury, lead and lead isotopes. We found over a 700-year period that rural Romans incorporated two times more mercury and lead into their bones than post-Romans inhabiting the same site, independent of sex or age. Atmospheric pollution sources contributed on average 57% (peaking at 85%) of the total lead incorporated into the bones in Roman times, which decreased to 24% after the decline of Rome. These values and accompanying changes in lead isotopic composition mirror changes in atmospheric Pb deposition recorded in local peatlands. Thus, skeletons are a time-transgressive archive reflecting contaminant exposure., SCOPUS: ar.j, info:eu-repo/semantics/published

Ombrotrophic peatlands are recognized archives of past atmospheric mineral dust deposition. Net dust deposition rates, grain size, mineral hosts and source areas are typically inferred from down-core elemental data. Although elemental analysis can be time efficient and data rich, there are some inherent limitations. X-ray diffraction (XRD) analysis allowsdirect identification of mineral phases in environmental samples but few studies have applied this method to peat samples and a well-developed protocol for extracting the inorganic fraction of highly organic samples (>95%) is lacking. We tested and compared different levels of pre-treatment: no pre-treatment, thermal combustion (300, 350, 400, 450, 500 and 550 degrees C) and chemical oxidation (H2O2 and Na2S2O8) using a homogenised highly organic (>98%) composite peat sample. Subsequently, minerals were identified by XRD. The results show that combustion is preferred to chemical oxidation because it most efficiently removes organic matter (OM), an important pre-requisite for identifying mineral phases by XRD analysis. Thermally induced phase transitions can be anticipated when temperature is the only factor to take into consideration. Based on the data required in this studythe recommended combustion temperature is 500 degrees C which efficiently removes OM while preserving a majority of common dust minerals.

Understanding past hydroclimate variability and related drivers is essential to improve climate forecasting capabilities especially in areas with high climatic sensitivity, such as the Mediterranean. This can be achieved by using a broad spectrum of high resolution, multiple proxy records which can also allow us to assess linkages between regional hydroclimate variability and shifts in the large-scale atmospheric patterns. Here, we present a multiproxy reconstruction of the central-eastern Mediterranean hydroclimate changes over the last 3600 years based on a sediment core from the Gialova Lagoon, a shallow coastal ecosystem in SW Peloponnese, Greece. Our combined dataset consists of the distribution and compound-specific carbon and hydrogen isotope (δ13C and δD) composition of n-alkanes, bulk organic matter properties and X-ray fluorescence (XRF) core scanning data. This approach was complemented with a semi-quantitative analysis of plant remains in the core. The results indicate a high contribution of local aquatic vegetation to organic matter. Large δ13C variations in predominantly aquatic plant-derived mid-chain alkanes (C23-25) mainly reflect changes in the aquatic plant abundance and their carbon source. Our data suggest that higher δ13C23-25 values (up to −19‰) largely correspond to expansion of aquatic vegetation during wet and/or cold periods causing carbon-limiting conditions in the water and assimilation of isotopically-enriched bicarbonate by the plants. The δD records of the individual n-alkanes (C17 to C31) exhibit a nearly identical pattern to each other, which implies that they all reflect changes in the source water isotope composition, driven by hydroclimate variability. In addition, the δD profiles are consistent with the XRF data with both proxies being driven by a common hydroclimate signal. We observe two major shifts from dry and/or warm periods at ca 3600-3000 cal BP and ca 1700-1300 cal BP to wet and/or cold episodes at ca 3000-2700 cal BP and ca 1300-900 cal BP. The period ca 700-200 cal BP is the wettest and/or coldest in our record and coeval with the Little Ice Age. The climatic fluctuation reported in this study can be explained by the relative dominance of high-latitude (e.g. North Atlantic Oscillation during winters) and the low-latitude atmospheric patterns (Intertropical convergence zone, Subtropical High and the effects of Asian monsoons during summers) which suggests an Atlantic-Mediterranean-Monsoon climate link in this area for the late Holocene.

The eastern Lesotho highlands are of considerable hydrological importance to southern Africa as a so-called ‘water tower’ for the surrounding region. Here, we contribute proxy-data inferring climate and vegetation changes over the past 1600 years, assessing in parallel inorganic and organic chemical analyses on a sediment core from Ladybird wetland, eastern Lesotho. Several proxies were used to determine changes in local vegetation dynamics, productivity, hydrology (δ13 C, δ15 N, C/N, TOC) and the input and source of the detrital components (Ca/Ti, CIA). The first part of the multi-proxy record (AD 400–800) shows stable terrestrial conditions and low detrital input, followed by higher variability in almost all proxies between ca. AD 900 and 1200. The δ13 C record infers a higher proportion of C4 vegetation, tentatively associated with higher temperatures during this phase, coeval with the Medieval Climate Anomaly (MCA). After AD 1200, local conditions change gradually from purely terrestrial, towards the typical wetland environment prevailing today. A higher proportion of C3 plants and possibly an increase in aquatic organisms within the organic matrix corresponds with decreasing detrital input, suggesting locally high available moisture in this part of Lesotho during the Little Ice Age (LIA). Although age-model constraints impedes a robust regional comparison, the inferred climate variability is discussed as a tentative response to enhanced mid-latitude cyclonic activity during LIA, and the variable MCA climate conditions as indirectly dictated by changes in solar activity.

The coastal areas of Eastern Mediterranean have long been the subject of research, due to their rapid geomorphological changes, but also because of their archaeological interest. Our study is focused on a shallow coastal lagoon of Peloponnese, Gialova Lagoon, which for several years has attracted the scientific interest of archaeologists, geomorphologists as well as sedimentologists. Gialova lagoon is located near the ancient city of Pylos, the kingdom of king Nestor during the Mycenaean period (1600–1100 BC). The objectives of this study are: (a) to reconstruct the middle to late Holocene depositional environments of the lagoon and (b) to correlate our data to already existing publications, in order to shed new light on the Holocene evolution of the lagoon and the associated coastal palaeoenvironmental changes. An 8 m deep vibracore was drilled and a multi proxy analysis was carried out on the sediment sequence, including sedimentological (grain size analysis and moment measures, total organic carbon – TOC, total nitrogen – TN and total phosphorus – TP), high resolution geochemical (XRF-scanning) and palaeontological (micro- and macro faunal) analysis. The chronological framework is based on five 14C datings forming the basis for an age depth model, calculated using the OxCal software. The radiocarbon dates from previous studies (6 cores, ∼20 dates) were also taken into account. The data synthesis and interpretation provided robust and coherent indications regarding the palaeoenvironment, shoreline changes and the rate of geomorphological changes of the coastal area of Gialova Lagoon, as well as useful information about the palaeonvironmental and palaeoclimatic conditions that prevailed during the Mycenaean period. The interpretation, reveal a transition from a shallow marine environment (6500-5800 yr B.P.) to a brackish/lagoonal (5800-3300 yr B.P.), followed by a shift towards a freshwater/marsh environment (3300 yr B.P. to present).

To study the long-range transport of atmospheric pollutants from lower latitude industrial areas to the Arctic, we analysed a peat core spanning the last ~700cal.yr (~1300-2000CE) from southern Greenland, an area sensitive to atmospheric pollution from North American and Eurasian sources. A previous investigation conducted in the same location recorded atmospheric lead (Pb) pollution after ~1845, with peak values recorded in the 1970s, and concluded that a North American source was most likely. To confirm the origin of the lead, we present new Pb isotope data from Sandhavn, together with a high-resolution record for mercury (Hg) deposition. Results demonstrate that the mercury accumulation rate has steadily increased since the beginning of the 19th century, with maximum values of 9.3μgm

A 12 m long lacustrine record from Sokli, N Finland, was analyzed for diatoms, non-pollen palynomorphs, macrofossils, pollen and geochemistry in order to reconstruct the development of a high-latit ...

The potential of dendrochemistry as a tool for tracing anthropogenic contamination at a glassworks site in southeastern Sweden was investigated through a multidisciplinary approach combining continuous high-resolution time series of tree rings and sediment profiles. Tree cores from Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and European aspen (Populus tremula) were analysed for their elemental composition using an energy dispersive X-ray fluorescence (ED-XRF) technique. Sediment cores were sampled along a transect extending from the pollution point source to unpolluted areas and analysed using core-scanning-XRF (CS-XRF). High contaminant concentrations in the soil were found for As (≈2000 ppm), Pb (>5000 ppm), Ba (≈1000 ppm) and Cd (≈150 ppm). The concentrations decreased with depth and distance from the pollution source. The dendrochemical analyses revealed alterations in the Barium, Chlorine and Manganese profiles, allowing the identification of seven potential asynchronous releases from the glassworks. Our results suggest that differences in the response of tree species to elemental uptake together with soil chemical properties dictate the success of dendrochemistry as an environmental monitoring tool.

Atmospheric dust plays an important role in terrestrial and marine ecosystems, particularly those that are nutrient limited. Despite that most dust originates from arid and semi-arid regions, recent research has shown that past dust events may have been involved in boosting productivity in nutrient-poor peatlands. We investigated dust deposition in a mid-latitude, raised bog, which is surrounded by a complex geology (paragneiss/schist, granite, quartzite and granodiorite). As proxies for dust fluxes, we used accumulation rates of trace (Ti, Zr, Rb, Sr and Y) as well as major (K and Ca) lithogenic elements. The oldest, largest dust deposition event occurred between ~8.6 and ~7.4 ka BP, peaking at ~8.1 ka BP (most probably the 8.2 ka BP event). The event had a large impact on the evolution of the mire, which subsequently transitioned from a fen into a raised bog in ~1500 years. From ~6.7 to ~4.0 ka BP, fluxes were very low, coeval with mid-Holocene forest stability and maximum extent. In the late Holocene, after ~4.0 ka BP, dust events became more prevalent with relatively major deposition at ~3.2–2.5, ~1.4 ka BP and ~0.35–0.05 ka BP, and minor peaks at ~4.0–3.7, ~1.7, ~1.10–0.95 ka BP and ~0.74–0.58 ka BP. Strontium fluxes display a similar pattern between ~11 and ~6.7 ka BP but then became decoupled from the other elements from the mid Holocene onwards. This seems to be a specific signal of the granodiorite batholith, which has an Sr anomaly. The reconstructed variations in dust fluxes bear a strong climatic imprint, probably related to storminess controlled by North Atlantic Oscillation conditions. Complex interactions also arise because of increased pressure from human activities.

XRF core scanning has evolved to become a standard analytical technique for the rapid assessment of elemental, density and textural variations in a wide range of sediments and other materials, with applications ranging from palaeoceanography, paleoclimatology, geology, and environmental forensics to environmental protection. In general, scanning provides rapid, non-destructive acquisition of elemental and textural variations at sub-millimetre resolution for a wide range of materials. Numerous procedural adaptations have been developed for the growing number of applications, such as analyses of unconsolidated, water-rich sediments, powdered soil samples, or resin bags. Here, practical expertise and guidance from the Itrax community, gained over 15 years, is presented that should provide insights for new and experienced users.

The application of statistical modeling is still infrequent in mercury research in peat, despite the ongoing debate on the weight of the diverse factors (climate, peat decomposition, vegetation changes, etc.) that may affect mercury accumulation. One of the few exceptions is the Hg record of Pinheiro mire (souheast Brazil). Previous studies on this mire modeled mercury using principal components regression and partial least squares. These methods assume independence between factors, which is seldom the case in natural systems, thus hampering the identification of mediating effects and interactions. To overcome these limitations, in this reserach we use structural equation modeling (PLS-SEM) to model mercury and bromine peat records - bromine has been used in some investigations to normalize mercury accumuation. The mercury model explained 83% of the variance and suggested a complex control: increased peat decomposition, dust deposition and humid climates enhanced mercury accumulation, while increased mineral fluxes resulted in a decrease in mercury accumulation. The bromine model explained 90% of the variation in concentrations: increased dust deposition and peat decomposition promoted bromine accumulation, while time (i.e. peat age) promoted bromine depletion. Thus, although mercury and bromine are both organically bound elements with relevant atmospheric cycles the weights of the factors involved in their accumulation differed significantly. Our results suggest caution when using bromine to normalize mercury accumulation. PLS-SEM results indicate a large time dependence of peat decomposition, catchment mineral fluxes, long-term climate change, and atmospheric deposition; while atmospheric dust, mineral fluxes and peat decomposition showed high to moderate climate dependency. In particular, they also point to a relevant role of autogenic processes (i.e. the build up and expansion of the mire within the catchment), which controlled local mineral fluxes; an aspect that has seldom been considered.

The Last Termination (19 000–11 000 a BP) with its rapid and distinct climate shifts provides a perfect laboratory to study the nature and regional impact of climate variability. The sedimentary succession from the ancient lake at Hässeldala Port in southern Sweden with its distinct Lateglacial/early Holocene stratigraphy (>14.1–9.5 cal. ka BP) is one of the few chronologically well‐constrained, multi‐proxy sites in Europe that capture a variety of local and regional climatic and environmental signals. Here we present Hässeldala's multi‐proxy records (lithology, geochemistry, pollen, diatoms, chironomids, biomarkers, hydrogen isotopes) in a refined age model and place the observed changes in lake status, catchment vegetation, summer temperatures and hydroclimate in a wider regional context. Reconstructed mean July temperatures increased between c. 14.1 and c. 13.1 cal. ka BP and subsequently declined. This latter cooling coincided with drier hydroclimatic conditions that were probably associated with a freshening of the Nordic Seas and started a few hundred years before the onset of Greenland Stadial 1 (c. 12.9 cal. ka BP). Our proxies suggest a further shift towards colder and drier conditions as late as c. 12.7 cal. ka BP, which was followed by the establishment of a stadial climate regime (c. 12.5–11.8 cal. ka BP). The onset of warmer and wetter conditions preceded the Holocene warming over Greenland by c. 200 years. Hässeldala's proxies thus highlight the complexity of environmental and hydrological responses across abrupt climate transitions in northern Europe.

Mineral dust deposition is a process often overlooked in northern mid-latitudes, despite its potential effects on ecosystems. These areas are often peat-rich, providing ample material for the reconstruction of past changes in atmospheric deposition. The highly organic (up to 99% in some cases) matrix of atmospherically fed mires, however, makes studying the actual dust particles (grain size, mineralogy) challenging. Here we explore some of the potentials and problems of using geochemical data from conservative, lithogenic elements (Al, Ga, Rb, Sc, Y, Zr, Th, Ti and REE) to build detailed dust records by using an example from the 8900-yr peat sequence from Store Mosse (the “Great Bog”), which is the largest mire complex in the boreo-nemoral region of southern Sweden. The four dust events recorded at this site were elementally distinct, suggesting different dominant mineral hosts. The oldest and longest event (6385–5300 cal yr BP) sees a clear signal of clay input but with increasing contributions of mica, feldspar and middle-REE-rich phosphate minerals over time. These clays are likely transported from a long-distance source (

The Eemian (the Last Interglacial; ca. 129–116 thousand years ago) presents a testbed for assessing environmental responses and climate feedbacks under warmer-than-present boundary conditions. However, climate syntheses for the Eemian remain hampered by lack of data from the high-latitude land areas, masking the climate response and feedbacks in the Arctic. Here we present a high-resolution (sub-centennial) record of Eemian palaeoclimate from northern Finland, with multi-model reconstructions for July and January air temperature. In contrast with the mid-latitudes of Europe, our data show decoupled seasonal trends with falling July and rising January temperatures over the Eemian, due to orbital and oceanic forcings. This leads to an oceanic Late-Eemian climate, consistent with an earlier hypothesis of glacial inception in Europe. The interglacial is further intersected by two strong cooling and drying events. These abrupt events parallel shifts in marine proxy data, linked to disturbances in the North Atlantic oceanic circulation regime., The Eemian period (120 ka) is considered a past analogue for future climatic warming, yet data from the high latitudes remains sparse. Here, the authors show that in Northern Europe, the Eemian saw dramatic climatic shifts, linked to changes in Earth’s orbit and North Atlantic oceanic circulation.

Biological proxies from the Sokli Eemian (Marine Isotope Stage 5e) paleolake sequence from northeast Finland have previously shown that, unlike many postglacial records from boreal sites, the lake becomes increasingly eutrophic over time. Here, principal components (PC) were extracted from a high resolution multi-element XRF core scanning dataset to describe minerogenic input from the wider catchment (PC1), the input of S, Fe, Mn, and Ca-rich detrital material from the surrounding Sokli Carbonatite Massif (PC2), and chemical weathering (PC3). Minerogenic inputs to the lake were elevated early in the record and during two abrupt cooling events when soils and vegetation in the catchment were poor. Chemical weathering in the catchment generally increased over time, coinciding with higher air temperatures, catchment productivity, and the presence of acidic conifer species. Abiotic edaphic processes play a key role in lake ontogeny at this site stemming from the base cation- and nutrient-rich bedrock, which supports lake alkalinity and productivity. The climate history at this site, and its integrated effects on the lake system, appear to override development processes and alters its long-term trajectory.

X-ray fluorescence (XRF) core scanning has become widely available for geological studies during the last decade. The data obtained from XRF core scanning, however, may be strongly influenced by the amount of organic matter, water content, density and porosity of the sediment matrix. In this study we discuss the usefulness of XRF core scanning to distinguish different kinds of organic-rich sediments and peat based on examples from tropical Lakes Kumphawapi and Nong Leng Sai in Thailand. We examined how sedimentary factors influence XRF core scanning analyses by comparing elemental and scattering ratios to lithological changes and quantitative LOI, TOC, biogenic silica (BSi) and grain-size values. Our comparison suggests that the (inc/coh) scattering ratio is of limited use as an indicator for variations in LOI and TOC in peaty gyttja or peat. In Lake Kumphawapi's sediments, Si/Ti ratios reflect clastic input associated with grain-size variations rather than BSi contents. The Ti-normalized ratios of Si, Zr, Sr, K and Rb are linked to mineral input and associated grain-size variations. We conclude that XRF core scanning of organic-rich tropical lake sediments and peat is useful to infer palaeoenvironmental conditions. However, XRF core scanning data does not stand-alone and needs to be underpinned by additional proxies.

The withdrawal of the Late Weichselian ice sheet and rapid isostatic uplift in southern Scandinavia led to the entrainment of large volumes of melt water within the proglacial Baltic Ice Lake (BIL). The eventual western outpost of BIL, Lake Vattern, has been a focal point for studying the dynamic retreat history of the Late Weichselian ice sheet in south central Sweden. This part of the deglacial history is described from an abundance of terrestrial studies, but, to date, no complimentary long sediment cores from Lake Vattern have been available. Here, we present the results from a unique, 74 m borehole in southern Lake Vattern that recovered a Late Pleistocene to Holocene sedimentary sequence. Physical and chemical analyses of the sediment and pore water, together with geophysical mapping, reveal glacial as well as postglacial imprints implying an oscillating ice sheet margin, evidence for neotectonic activity and one or more marine incursions into the lake during deglaciation. We attribute the glaciotec...

Lake sediments and peat deposits from two basins on Nightingale Island (37 degrees S), in the Tristan da Cunha archipelago, South Atlantic, have been analyzed. The studies were focused on the time period 16.2-10.0 cal ka BP, determined by 36 C-14 dates from the two sequences. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, C and N analyzes, stable isotopes (C-13 and N-15), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. In addition, climate model simulations were carried out. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. The climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich I event in the north and a southward displacement of the ITCZ. The development on the island after 16.2 cal ka BP is determined by the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). The period 16.2-14.75 cal ka BP was characterized by varying influence from SHW and with STF situated south of Tristan da Cunha, ending with a humidity peak and cooler conditions. The stable conditions 14.7-14.1 cal ka BP with cool and fairly arid conditions imply that STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The most unstable period, 14.1-12.7 cal ka BP, indicates incessant latitudinal shifts of the zonal circulation, perhaps related to climate variability in the Northern Hemisphere and bipolar seesaw mechanisms as the strength of the Atlantic Meridional Overturning Circulation (AMOC) varied. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming seems to have occurred in the earliest part of the Holocene, but this period was also characterized by humidity shifts, possibly an effect of retraction and expansion phases of SHW during AMOC variations in the north. (C) 2015 Elsevier Ltd. All rights reserved. (Less)

In this paper, we highlight the importance of combining multi-proxy analysis of lake sediments with associated catchment geomorphology to better understand the late Holocene palaeoenvironmental evo ...

We have developed a novel, quick and non-destructive method for tracing flood events in caves through the analysis of a stalagmite thick section with an XRF core scanner. The analyzed stalagmite has multiple horizons of fine sediments from past flood events intercalated with areas of cleaner calcite. Flood events detected from the elemental XRF core scanning data show good agreement with the position of flood horizons identified in petrographic thin sections. The geochemical composition of the individual flood layers shows that in certain cases the clay horizons had a distinct geochemical fingerprint suggesting that it may be possible to distinguish individual flood layers based on their geochemistry. This presents the possibility for using flood events as marker horizons to chronologically tie different speleothems in a cave to each other.

The fossil diatom record from the Hasseldala Port palaeolake, southeastern Sweden, offers an excellent opportunity to investigate how past climatic shifts influenced catchment conditions and early lake development. The record, dating to between 13 900 and 11 200 cal. a BP, covers a climatically dynamic period, starting with deglaciation followed by oscillations between warmer and colder climate states. The stratigraphical changes in the fossil diatom assemblages show a trend of less open-water taxa and a successively more complex periphytic community as the lake shallows and the aquatic habitat structure develops. A diatom-based reconstruction of lake water pH indicates a natural acidification trend early in the record from 13 900 to 12 500 cal. a BP. From 12 500 cal. a BP, coincident with the start of climate cooling, to 11 300 cal. a BP this trend is disrupted and lake waters become more alkaline. A cooler and drier climate most likely resulted in reduced soil organic matter build-up as well as more frozen ground that impeded hydrological flow and decreased the input of dissolved organic matter and organic acids into the lake system. This study demonstrates the importance of the hydrological system as a link between terrestrial and aquatic ecosystems during early lake ontogeny.

Glaciomarine clay found west of Mt Billingen, central Sweden, contains two distinct varve units separated by a sand layer that we interpret to be sediment deposited in the North Sea during the catastrophic drainage of the Baltic Ice Lake (BIL). The lower varve series was deposited proximal to the retreating ice margin and consists of varves that grade upward from gray to red. The upper varve series was deposited after the drainage event when fresh water within the Baltic basin flowed westward north of Billingen; the upper varves grade from red to gray. Grain size, elemental composition (determined by X-ray fluorescence (XRF)), iron and organic-carbon content vary within each varve, with values that grade upward through each varve, but with a sharp contact with the overlying varve. The two varve units differ from each other, with the lower sequence being coarser and the upper containing a higher iron and organic-carbon content. We attribute the differences between pre- and post-drainage varves to reflect changes in distance to the ice margin and provenance. The stratigraphy at the site suggests that the BIL drainage lasted

The development of a glacial lake impounded along the retreating, northeastern ice margin of the Fennoscandian Ice Sheet during the last deglaciation and environmental conditions directly following the early Holocene deglaciation have been studied in NE Finland. This so-called Sokli Ice Lake has been reconstructed previously using topographic and geomorphologic evidence. In this paper a multiproxy approach is employed to study a 3-m-thick sediment succession consisting of laminated silts grading into gyttja cored in Lake Loitsana, a remnant of the Sokli Ice Lake. Variations in the sediment and siliceous microfossil records indicate distinct changes in water depth and lake size in the Loitsana basin as the Sokli Ice Lake was drained through various spillways opening up along the retreating ice front. Geochemical data (XRF core-scanning) show changes in the influence of regional catchment geochemistry (Precambrian crystalline rocks) in the glacial lake drainage area versus local catchment geochemistry (Sokli Carbonatite Massif) within the Lake Loitsana drainage area during the lake evolution. Principal component analysis on the geochemical data further suggests that grain-size is an additional factor responsible for the variability of the sediment geochemistry record. The trophic state of the lake changed drastically as a result of morphometric eutrophication once the glacial lake developed into Lake Loitsana. The AMS radiocarbon dating on tree birch seeds found in the glaciolacustrine sediment indicates that Lake Loitsana was deglaciated sometime prior to 10 700 cal. a BP showing that tree Betula was present on the deglaciated land surrounding the glacial lake. Although glacial lakes covered large areas of northern Finland during the last deglaciation, only few glaciolacustrine sediment successions have been studied in any detail. Our study shows the potential of these sediments for multiproxy analysis and contributes to the reconstruction of environmental conditions in NE Finland directly following deglaciation in the early Holocene.

A new stomatal proxy-based record of CO2 concentrations ([CO2]), based on Betula nana (dwarf birch) leaves from the Hasseldala Port sedimentary sequence in south-eastern Sweden, is presented. The record is of high chronological resolution and spans most of Greenland Interstadial 1 (GI-1a to 1c, Allerod pollen zone), Greenland Stadial 1 (GS-1, Younger Dryas pollen zone) and the very beginning of the Holocene (Preboreal pollen zone). The record clearly demonstrates that i) [CO2] were significantly higher than usually reported for the Last Termination and ii) the overall pattern of CO2 evolution through the studied time period is fairly dynamic, with significant abrupt fluctuations in [CO2] when the climate moved from interstadial to stadial state and vice versa. A new loss-on-ignition chemical record (used here as a proxy for temperature) lends independent support to the Hasseldala Port [CO2] record. The large-amplitude fluctuations around the climate change transitions may indicate unstable climates and that “tippingpoint” situations were involved in Last Termination climate evolution. The scenario presented here is in contrast to [CO2] records reconstructed from air bubbles trapped in ice, which indicate lower concentrations and a gradual, linear increase of [CO2] through time. The prevalent explanation for the main climate forcer during the Last Termination being ocean circulation patterns needs to re-examined, and a larger role for atmospheric [CO2] considered.

The long-term climatic and environmental history of Southeast Asia, and of Thailand in particular, is still fragmentary. Here we present a new C-14-dated, multi-proxy sediment record (TOC, C/N, CNS ...

There is a relatively good understanding of the paleoenvironmental changes that have occurred in southern Sweden since the Late Glacial. A main exception, however, is the sedimentary response of la ...

X-ray fluorescence (XRF) core scanning is a relatively new arrangement of a classic analytical technique which allows for non-destructive, in situ XRF analysis of sediment cores from submillimetre resolution upwards. In this contribution we explore the use of XRF core scanning for tephrochronology based on the analysis of three gyttja-rich sediment cores from the Faroe Islands. Using a combination of optical and radiographic images, analytical parameters and elemental profiles (Si, K, Ca, Ti, Mn, Fe, Sr and Zr), higher concentration basaltic tephra layers (>1000 shards/cm3) were positively identified. The XRF core scanning did not capture the lower concentration (3) rhyolitic layers found in the core. The elemental data generated for the detected tephra layers using XRF core scanning was not comparable to individual shard analysis by electron microprobe. We recommend using XRF core scanning for tephra screening in order to localize depths for high-resolution subsampling and to avoid depths where sediment mixing has caused tailing/mixing of the tephra signal. At the studied site the basaltic Saksunarvatn ash as well as a tephra belonging to the Askja-S/10 ka eruption were identified.

X-ray fluorescence (XRF) scanning of unlithified, untreated sediment cores is becoming an increasingly common method used to obtain paleoproxy data from lake records. XRF-scanning is fast and delivers high-resolution records of relative variations in the elemental composition of the sediment. However, lake sediments display extreme variations in their organic matter content, which can vary from just a few percent to well over 50%. As XRF scanners are largely insensitive to organic material in the sediment, increasing levels of organic material effectively dilute those components that can be measured, such as the lithogenic material (the closed-sum effect). Consequently, in sediments with large variations in organic material, the measured variations in an element will to a large extent mirror the changes in organic material. It is therefore necessary to normalize the elements in the lithogenic component of the sediment against a conservative element to allow changes in the input of the elements to be addressed. In this study we show that Al, which is the lightest element that can be measured using the Itrax XRF-scanner, can be used to effectively normalize the elements of the lithogenic fraction of the sediment against variations in organic content. We also show that care must be taken when choosing resolution and exposure time to ensure optimal output from the measurements.

The Les Echets sediment sequence has recently been the subject of a high-resolution, multi-proxy study which revealed shifts in lake productivity linked to Greenland stadials and interstadials over the last 40 ka (Wohlfarth et al., 2008. Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-16 ka. Geology 36: 407-410). Here we present new elemental data for this sequence as acquired using an X-ray fluorescence core scanning system which provides in situ high-resolution, continuous, multi-element analyses. It was found that the strength of associations between the studied elements (Ti, Rb, K, Zr, Si, Ca, Sr, Mn and Fe) varied over time with changes in lake status which are ultimately driven by changes in climate. Increases in fine-grained, detrital input (as indicated by Ti, Rb, K and Zr/Rb) overlap with independently established periods of lower lake productivity and are interpreted to represent more arid conditions. Several of these arid periods are coincident with low diatom concentrations and the timing of Heinrich events H4, H3 and H2. The duration of the environmental impacts linked to the H events varied by proxy with elemental data (Ti and Zr/Rb) estimating shorter events than the diatom data. Periods of lower detrital input and coarser grain sizes agreed in time with periods of higher lake productivity. The elemental data provide new insights into hydrological changes and related sediment processes within the catchment, and highlight the need for multi-element and multi-proxy approaches when reconstructing climate change using lacustrine sediment sequences. Copyright # 2011 John Wiley & Sons, Ltd.

The coupling of laser ablation (LA) to inductively coupled plasma-mass spectrometry (ICP-MS) enables the direct analysis of solid samples with micrometric resolution. Analysis is often restricted to relatively small samples owing to the dimensions of conventional ablation cells. Here, we assess the performance of a large rectangular, commercially-available sample cell which enables analysis over a 10.2 x 5.2 cm(2) area. Comparison with the conventional cell shows a small to moderate performance decrease for the large cell resulting from the dilution of ablated particles in a larger volume with a 4-31% lower signal output and longer signal tailings. The performance of this cell is however sufficient for the determination of both major and trace elements in many kinds of samples. The applicability of the large cell LA-ICP-MS setup was demonstrated by the determination of Al, Si, Mn, Fe, Cu, Zn Pb and U in sediment core sections at a resolution of 0.6 mm. Detection limits for sediment analysis were 7 mg Al kg(-1), 68 mg Si kg(-1), 0.5 mg Mn kg(-1), 20 mg Fe kg(-1), 0.2 mg Cu kg(-1), 0.3 mg Zn kg(-1), 0.08 mg Pb kg(-1) and 0.003 mg U kg(-1). Cyclic patterns, which would have been overlooked by conventional analysis at cm resolution, were observed in analysed sediments. This study demonstrates the potential of LA-ICP-MS in environmental analysis, with the large sample cell setup offering the possibility to analyse a wider range of samples without sectioning.

Stable lead (Pb) isotope data from pre-contamination peat sections has the potential to contribute to our understanding of earth system processes (e.g., atmospheric circulation, erosion, volcanic activity) in the past. Key questions arise however. Can the Pb isotopes archived in peat records be used for assessing aerosol dynamics on a hemispheric scale or do they mainly reflect inputs from local soils? What natural Pb sources are important and do contributions vary over time? In order to answer these questions we have synthesized all available Pb isotope data from pre-contamination peat sections in Europe, Australia, North America and South America. We specifically examine the spatial and temporal variability of the Pb isotope records and identify regionally important trends and Pb sources. A pooling of all available pre-contamination peat data generated an average natural 206Pb/207Pb background ratio of 1.21±0.05 (2σ, n=300)(206Pb/204Pb= 18.90±0.86, 207Pb/204Pb= 15.66±0.10 and 208Pb/204Pb= 38.74±0.57, n=207). The majority of the records showed limited temporal and compositional agreement, suggesting that the peat record receives mainly inputs from local (

International audience; Peatland of the eastern Qinghai­Tibetan Plateau lies at the convergence of the East Asian and Indian monsoon systems in eastern Asia. To understand the evolution of this peatland and its potential to provide new insights into the Holocene evolution of the East Asian monsoon a 6 m peat core was collected from the undisturbed central part of a peat deposit near Hongyuan. The age-depth profile was determined using 16 14C-AMS age dates, the peat analysed for a range of environmental variables including carbon, nitrogen and hydrogen concentration, bulk density, d13C and the associated spring water analysed for hydrogen and oxygen isotopes. The age-depth profile of the recovered peat sequence covers the period from 9.6 to 0.3 kyr BP and is linear indicating that the conditions governing productivity and decay varied little over the Holocene. Using changes in carbon density, organic carbon content and its d13C, cold dry periods of permafrost characterised by low density and impeded surface drainage were identified. The low d18O and dD values of the spring water emanating around the peat deposit, down to -13.8 and -102 (VSMOW), respectively, with an inverse relationship between electrical conductivity and isotopic composition indicate precipitation under colder and drier conditions relative to the present day. In view of the current annual mean air temperature of 1 °C this suggests conditions in the past have been conducive to permafrost. Inferred periods of permafrost correspond to independently recognised cold periods in other Holocene records from across China at 8.6, 8.2­7.8, 5.6­4.2, 3.1 and 1.8­1.5 kyr BP. The transition to a cold dry climate appears to be more rapid than the subsequent recovery and cold dry periods at Hongyuan are of longer duration than equivalent cold dry periods over central and eastern China. Light­dark banding peat on a scale of 15­30 years from 9.6 to 5.5 kyr BP may indicate a strong influence of decadal oscillations possibly the Pacific Decadal Oscillation and a potential link between near simultaneous climatic changes in the northwest Pacific, ENSO, movement of the Intertropical Convergence Zone and the East Asian Monsoon.