Poznan Radiocarbon Laboratory

Poznań, Poland

Poznan Radiocarbon Laboratory

Poznań, Poland
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Esmeijer-Liu A.J.,University Utrecht | Kurschner W.M.,University of Oslo | Lotter A.F.,University Utrecht | Verhoeven J.T.A.,University Utrecht | And 2 more authors.
Water, Air, and Soil Pollution | Year: 2012

In this study, we test whether the δ 13C and δ 15N in a peat profile are, respectively, linked to the recent dilution of atmospheric δ 13CO 2 caused by increased fossil fuel combustion and changes in atmospheric δ 15N deposition. We analysed bulk peat and Sphagnum fuscum branch C and N concentrations and bulk peat, S. fuscum branch and Andromeda polifolia leaf δ 13C and δ 15N from a 30-cm hummocklike peat profile from an Aapa mire in northern Finland. Statistically significant correlations were found between the dilution of atmospheric δ 13CO 2 and bulk peat δ 13C, as well as between historically increasing wet N deposition and bulk peat δ 15N. However, these correlations may be affected by early stage kinetic fractionation during decomposition and possibly other processes. We conclude that bulk peat stable carbon and nitrogen isotope ratios may reflect the dilution of atmospheric δ 13CO 2 and the changes in δ 15N deposition, but probably also reflect the effects of early stage kinetic fractionation during diagenesis. This needs to be taken into account when interpreting palaeodata. There is a need for further studies of δ 15N profiles in sufficiently old dated cores from sites with different rates of decomposition: These would facilitate more reliable separation of depositional δ 15N from patterns caused by other processes. © Springer Science+Business Media B.V. 2011.

Martincic A.,Zaloska cesta 78A | Goslar T.,Adam Mickiewicz University | Goslar T.,Poznan Radiocarbon Laboratory
Holocene | Year: 2010

This paper compares a high resolution, near-annual pollen record from the šijec raised bog (1194 m a.s.l., Pokljuka, Slovenia) with historical land-use maps in order to understand how the Alpine environment has altered because of changeable economic trends in the fifteenth, nineteenth and twentieth centuries AD. In the fifteenth century AD the study site was surrounded by mixed forest (Fagus, Abies, Picea, Quercus) and agricultural fields and pastures, but by the beginning of the nineteenth century AD the landscape had become more open, with very intensive agricultural land-use and grazing. The forest composition also changed: Fagus and Abies declined because of intensive grazing and ironworks (forest clearance and charcoal production). In the second half of the nineteenth and at the beginning of the twentieth century AD, forest recovered, but farming activities continued and, as a result of the forestry policy, Picea prevailed. After AD 1945 agricultural economy declined and mixed forests, which today cover more than 70% of land, are still expanding. © The Author(s) 2010.

Finsinger W.,French National Center for Scientific Research | Finsinger W.,University Utrecht | Schoning K.,Geological Survey of Sweden | Hicks S.,University of Oulu | And 5 more authors.
Journal of Quaternary Science | Year: 2013

We present a record of peatland development in relation to climate changes and human activities from the Palomaa mire, a remote site in northern Finland. We used fine-resolution and continuous sampling to analyse several proxies including pollen (for vegetation on and around the mire), testate amoebae (TA; for mire-wetness changes), oxygen and carbon isotopes from Sphagnum cellulose (δ18O and δ13C; for humidity and temperature changes), peat-accumulation rates and peat-colour changes. In spite of an excellent accumulation model (30 14C dates and estimated standard deviation of sample ages <1 year in the most recent part), the potential to determine cause-effect (or lead-lag) relationships between environmental changes and biotic responses is limited by proxy-specific incorporation processes below the actively growing Sphagnum surface. Nevertheless, what emerges is that mire development was closely related to water-table changes rather than to summer temperature and that water-table decreases were associated with increasing peat-accumulation rates and more abundant mire vegetation. A rapid fen-to-bog transition occurred within a few years around AD 1960 when the water table decreased beyond the historical minimum, supporting the notion that mires can rapidly shift into bogs in response to allogenic factors. © 2012 John Wiley & Sons, Ltd.

Rosqvist G.C.,University of Stockholm | Leng M.J.,University of Leicester | Leng M.J.,British Geological Survey | Goslar T.,Adam Mickiewicz University | And 10 more authors.
Quaternary Science Reviews | Year: 2013

Here we present δ;18Odiatom data from two high-latitude lakes; one has short residence time and a water isotopic composition (δ18Olake) that fluctuate due to seasonal variations in precipitation and temperature, and the other has δ18Olake that is influenced by longer lake water residence times and evaporation. The δ18Odiatom records reveal common responses to precipitation forcing over the past millennium. Relatively wet summers are inferred from δ18Odiatom between 1000 and 1080 AD, 1300 and 1440 AD, and during the early 19th century, coincided with periods of high cloud cover inferred from tree-ring carbon isotopes, and other data for high Arctic Oscillation index. While relatively dry summers with increasing influence of winter snow are indicated between 1600 and 1750 AD. The co-response between carbon isotopes in trees and oxygen isotopes in diatoms strengthens the relationship between cloud cover and precipitation and the hypothesis that these changes were the result of significant regional shifts in atmospheric circulation. © 2012 Elsevier Ltd.

Michalska D.,Adam Mickiewicz University | Czernik J.,Poznan Radiocarbon Laboratory
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015

Lime mortars as a mixture of binder and aggregate may contain carbon of various origins. If the mortars are made of totally burnt lime, radiocarbon dating of binder yields the real age of building construction. The presence of carbonaceous aggregate has a significant influence on the 14C measurements results and depending on the type of aggregate and fraction they may cause overaging. Another problem, especially in case of hydraulic mortars that continue to be chemically active for a very long time, is the recrystallization usually connected with rejuvenation of the results but also, depending on local geological structures, with so called reservoir effect yielding apparent ages. An attempt in separating the binder from other carbonaceous components successfully was made for samples from Israel by Nawrocka-Michalska et al. (2007). The same preparation procedure, after taking into account the petrographic composition, was used for samples coming from Poland, Nawrocka et al. (2009). To verify the procedure used previously for non-hydraulic samples determination an experimental tests on carbonaceous mortars with crushed bricks from Novae in Bulgaria were made. Additionally, to identify different carbonaceous structures and their morphology, a cathodoluminescence and scanning electron microscope with electron dispersive spectrometer were applied. The crushed bricks and brick dust used in mortars production process have been interpreted as an alternative use to other pozzolanic materials. The reaction between lime and pozzolanic additives take place easily and affects the rate and course of carbonates decomposition in orthophosphric acid, during the samples pretreatment for dating. The composition of the Bulgarian samples together with influence of climate conditions on mortar carbonates do not allow for making straightforward conclusions in chronology context, but gives some new guidelines in terms of hydraulic mortars application for dating. This work has mainly methodological character, illustrating the special preparation methods used for mortars with complicated (in context of radiocarbon dating) petrographic composition. The local geology combined with finding sources of raw materials for the production of mortars is important issue in final interpretation of the 14C measurement results. © 2015 Elsevier B.V. All rights reserved.

van der Knaap W.O.,University of Bern | Lamentowicz M.,Adam Mickiewicz University | Lamentowicz M.,Ecole Polytechnique Federale de Lausanne | Lamentowicz M.,University of Neuchatel | And 13 more authors.
Quaternary Science Reviews | Year: 2011

We present a record of peatland development during the last 1000 years from Mauntschas mire in the eastern Swiss Alps (Upper Engadine valley; 1818 m a.s.l.) inferred from testate amoebae (pH and depth to the water table (DWT) reconstructions), stable oxygen isotopes in Sphagnum (δ18O; proxy for water vapour pressure) and carbon isotopes in Sphagnum (δ13C; proxy for mire surface wetness), peat accumulation rates, charcoal (indicating local burning), pollen and spores (proxies for human impact), and plant macrofossils (reflecting local vegetation and trophic state). Past human impact on the local mire conditions was strong but fluctuating during AD 1000-1570 (±50 yr; depth-age model based on 29 14C AMS dates) with local irrigation of nutrient-enriched water and grazing. Human impact was minor AD 1570-1830 (±30 yr) with partial recovery of the local mire vegetation, and it was absent AD 1830 (±30 yr)-present when hummock formation took place. Correlations among DWT, pH, δ13C, and δ18O, carried out both with the raw data and with linear trends removed, suggest that the factors driving peatland development changed over time, since only testate amoeba-based pH and DWT co-varied during all the three aforementioned periods. δ18O correlates with δ13C only in the period AD 1830-present and with DWT only during AD 1570-1830, δ13C correlates with DWT only during AD 1000-1570. Part of this apparent instability among the four time series might be attributed to shifts in the local mire conditions which potentially formed very different (non-analogue) habitats. Lack of analogues, caused, for example, by pre-industrial human impact, might have introduced artefacts in the reconstructions, since those habitats are not well represented in some proxy transfer functions. Human impact was probably the main factor for peatland development, distorting most of the climate signals. © 2011 Elsevier Ltd.

Rozanski K.,AGH University of Science and Technology | Klisch M.A.,AGH University of Science and Technology | Wachniew P.,AGH University of Science and Technology | Gorczyca Z.,AGH University of Science and Technology | And 4 more authors.
Geochimica et Cosmochimica Acta | Year: 2010

Two water-based oxygen-isotope geothermometers (calcite-cellulose and silica-cellulose) were tested using well-dated intervals of laminated sediment retrieved from Lake Gościaz, a small hardwater lake in central Poland. Five sections spanning ca. 90-200years of deposition were selected and subsampled at approximately decadal resolution to characterize relatively stable climatic and hydrologic conditions during the middle of the Younger Dryas cold period, the rapid environmental changes that occurred at the Younger Dryas-Preboreal (YD-PB) boundary, and three subsequent periods of relative stability during the early, middle and late Holocene. The two geothermometers are based on the premise that aquatic cellulose δ18O serves as a direct proxy for lakewater δ18O, thereby allowing resolution of temperature signals in δ18O records obtained from co-existing authigenic calcite or diatom silica. Qualitatively consistent results from the calcite-cellulose geothermometer were obtained for all five intervals, clearly showing the expected low epilimnion water temperatures in the mid-YD, rapid warming during the YD-BP transition and maximum temperatures during the early Holocene, followed by slightly lower temperatures during the middle and late Holocene. Results from the silica-cellulose geothermometer also showed lower temperatures during the YD than the late Holocene, although insufficient diatom silica for analysis was present in the intervening intervals. The calcite-cellulose geothermometer yielded consistently higher estimates of epilimnion temperatures than the silica-cellulose thermometer in the YD and late Holocene intervals, and unrealistically high values throughout the Holocene. We speculate that the calcite-cellulose geothermometer is influenced by kinetic effects during rapid carbonate precipitation, which offsets temperature-dependent fractionation and thus leads to high temperature estimates. In contrast, the silica-cellulose geothermometer may be affected by the production of diatom silica early in the spring, prior to seasonal warming and isotopic enrichment of the epilimnion, thus generating low temperature estimates. © 2010 Elsevier Ltd.

van der Knaap W.O.,University of Bern | van Leeuwen J.F.N.,University of Bern | Goslar T.,Adam Mickiewicz University | Goslar T.,Poznan Radiocarbon Laboratory | And 2 more authors.
Vegetation History and Archaeobotany | Year: 2012

Three mires and a small lake in the Swiss and Austrian Alps were studied palynologically at high resolution, covering the last 1,000, 400, 50 and 1,200 years, respectively. Methodological lessons include: (1) Sub-decadal resolution in upper, little-decomposed peat layers reveals recurrent marked fluctuations in both percentages and influx of regional tree-pollen types, reflecting variations in pollen production rather than in plant-population sizes. (2) Intermittent, single-spectrum pollen maxima in samples of sub-decadal resolution indicate pollen transport in clumps. This type of pollen transport may remain unrecognized in sections with lower sampling resolution, which may then lead to inappropriate interpretation in terms of plant-population sizes. (3) The detection of short-lived phases of human impact in decomposed peat requires sampling intervals as close as 0.2 cm. (4) PAR (pollen influx) may reflect vegetation dynamics more faithfully than percentages. Reliable PAR, however, is difficult to achieve in Alpine mires due to past human impact on peat growth, even when complex depth-age modelling techniques are used. Critical comparison of PAR with percentages is therefore essential. (5) Careful consideration of spatial scales in pollen signals (local-regional and subdivisions) is essential for a realistic palaeo-ecological interpretation. Results in terms of past human impact on vegetation are summarized as follows: (1) Trends in pollen types reflecting regional human action are in general agreement with earlier findings for the western Swiss Alps, allowing for regional differences. (2) All mires in the Alps investigated here and in an earlier study experienced human impact during the last millennium. The studied small lake, lying in sub-alpine pasture, records forest dynamics at a lower elevation since a. d. 800. © 2011 Springer-Verlag.

Michalska D.,Adam Mickiewicz University | Pazdur A.,Silesian University of Technology | Czernik J.,Poznan Radiocarbon Laboratory | Szczepaniak M.,Adam Mickiewicz University | Zurakowska M.,University of West of Scotland
Geochronometria | Year: 2012

Lime mortars may contain carbon from different origins. If the mortars are made of totally burnt lime, radiocarbon dating yields the true age of building construction. The presence of carbonaceous aggregates gives the so-called dead carbon effect, which may generate older ages. Another source of carbon is charcoal present in mortars. An attempt has been made to apply the radiocarbon method to mortars of archaeologically estimated age from the Dead Sea region. Petrographical analyses of these samples show the carbonaceous character of the binder and large amounts of limestone aggregate. Determination of the mineral composition of the mortars and comparison with the geology of the surrounding, allows the provenance of the raw materials to be identified. They probably represent the Cretaceous rocks of the Judea Group. Separate radiocarbon dates were made on bulk mortar samples, binder, charcoal fragments and separated fractions from mortars. In the case of binder-aggregate mixture the reservoir effect correction has been applied. © 2012 Versita Warsaw and Springer-Verlag Wien.

Goslar T.,Adam Mickiewicz University | Goslar T.,Poznan Radiocarbon Laboratory | Andersen G.,University of Bergen | Krzywinski K.,University of Bergen | Czernik J.,Poznan Radiocarbon Laboratory
Radiocarbon | Year: 2013

Reconstructions are presented of past growth rates of 10 Acacia tortilis trees, 5 growing at an arid site (Gebeit, Sudan) and 5 at a hyperarid site (Wadi Nuqrus, Egypt). The reconstructions were made using a free-shape age-depth model based on a series of 14C dates obtained on samples taken along the wood cores retrieved from the trunks of the trees (78 dates in total). In spite of the large difference in annual precipitation between the 2 sites, the range of ages of the trees (60-350 yr) and the variability in their growth rates are quite similar across both sites, whereas within-site growth rates are quite different even for closely spaced individuals. However, the pattern of growth rates of Acacias from the hyperarid Wadi Nuqrus indicates 2 periods of different aridity (the less arid AD 1650-1780 and more arid AD 1780-1930), while at Gebeit no such pattern has been detected. © 2013 by the Arizona Board of Regents on behalf of the University of Arizona.

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