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Diatom-based reconstruction of trophic status changes recorded in varved sediments of Lake Żabińskie (northeastern Poland), AD 1888-2010

Witak M., Hernández-Almeida I., Grosjean M., Tylmann W.

Oceanological and Hydrobiological Studies

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2017

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Vol. 46, No. 1

1--17

EN

We investigated diatom assemblages in surface sediments of 46 lakes in northern Poland and developed a diatom-based transfer function to infer epilimnetic total phosphorus (TP) concentrations. Multivariate ordination techniques (DCA, CCA) were used to identify major environmental gradients and to evaluate the effect of environmental parameters on the distribution of diatoms in the modern diatom dataset. The transfer function was developed using PLS, WA and WA-PLS models, and applied to a varved sediment core from Lake Żabińskie, AD 1888-2010. Annually-resolved quantitative reconstruction of TP concentrations shows that multidecadal changes in the TP level reflect the local settlement history, land-use changes and development of agriculture and tourism. The period of high trophic levels with maximum values of TP was documented until the late 1920s. In the 1930s-1970s period, TP generally decreased and eutraphentic flora was partly replaced by oligotraphentic and oligo-mesotraphentic diatom taxa. The reconstructed TP concentrations have started to increase from the 1970s. After the 1950s, strong short-term fluctuations of TP values were noted and explained by interactions between meteorological conditions, water column mixing and nutrient cycling in the lake.

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Comparing Varve Counting And 14C-Ams Chronologies In The Sediments Of Lake Żabińskie, Northeastern Poland: Implications For Accurate 14C Dating Of Lake Sediments

Bonk A., Tylmann W., Goslar T., Wacnik A., Grosjean M.

Geochronometria

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2015

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Vol. 42, no.1

159--171

EN

Varved lake sediments from Lake Żabińskie (northeastern Poland) provide a highresolution calendar-year chronology which allows validation of 14C dating results. Microscopic analysis of the varve microfacies revealed that laminations found in Lake Żabińskie were biogenic (calcite) varves. Three independent counts indicated a good preservation quality of laminae in the 348 cm long sediment profile which contained 1000+12/-24 varves. The varve chronology was validated with the 137Cs activity peaks, the tephra horizon from the Askja eruption at AD 1875 and with the timing of major land-use changes of known age inferred from pollen analysis. 32 AMS 14C dates of terrestrial macrofossils distributed along the profile were compared with the varve chronology. After identification of outliers, the free-shape model performed with 21 14C dates provided the best possible fit with the varve chronology. We observed almost ideal consistency between both chronologies from the present until AD 1250 while in the lower part (AD 1000–1250) the difference increases to ca. 25 years. We demonstrate that this offset can be explained by too old radiocarbon ages of plant remains transported to the lake by the inflowing creek. Results of this study highlight that careful interpretation of radiocarbon age-depth models is necessary, especially in lakes where no annual laminations are observed and no independent method are used for cross-validation.

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Nowe stanowiska laminowanych osadów jeziornych na Pojezierzu Kaszubskim

Tylmann W., Zawadzka M.

Przegląd Geologiczny

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2008

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Vol. 56, nr 5

404-408

EN

Annually laminated lake sediments are a very valuable source of paleoecological information because they provide a precise timescale in calendar years and limited post-depositional disturbances. They are formed in specific conditions that enable not only the formation but also preservation of lamination, hence they rarely occur. The goal was to find lakes with annually laminated sediments in Kashubian Lakeland which can provide new high-resolution paleoenvironmental and paleoclimatic data for this part of Europe. Based on statistical analyses including catchment geology and topography, morphometric lake basin features and hydrological parameters, a pre-selection of 22 lakes with water depths ranging from 15 to 35 m was carried out. Gravity cores (30–90 cm long) were obtained from 18 of these lakes during a field survey in 2006. The cores were split lengthwise, photographed digitally and examined carefully. Four of the lakes studied show distinct alternations of pale and dark laminae. For three lakes (Kramsko Duże, Kramsko Małe and BorowoWielkie) such laminations were restricted to sections of the cores only. Lake Suminko was deemed the most promising site with its laminations covering the entire taken core. In all the cases, biochemical varves were developed with pale spring/summer layers composed of autochthonous carbonates and dark fall/winter layers made of organic detritus and minerogenic particles.

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Laminowane osady denne jeziora Szurpiły jako podstawa rekonstrukcji zmian środowiska przyrodniczego w północno - wschodniej Polsce

Kinder M., Tylmann W., Ohlendorf C., Zolitschka B.

Landform Analysis

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2008

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Vol. 9

241--246

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Estimating recent sedimentation rates using 210 PB on the example of morphologically complex lake (Upper Lake Raduńskie, N Poland)

Tylmann W.

Geochronometria

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2004

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Vol. 23

21-26

EN

Upper Lake Raduńskie is a classical channel lake with a typical complexity of lake basin morphology. This study presents the results of 210Pb measurements in four cores of recent sediments taken from different parts of the lake. The unsupported 210Pb activity plotted on a logarithmic scale against the cumulative dry mass decreased almost linearly. Sedimentation rates were determined from the mean slope of the profile (CF:CS model). A diversity of calculated values was significant, the highest value was found in the core RAD02/6 located in the deepest part of the lake. Both 210Pb inventories and fluxes were higher than that expected from atmospheric fallout estimated for this part of Europe. Factors influencing differences between atmospheric fallout and sediment record may include inputs from the catchment and sediment focusing, which seems to be the main reason of sedimentation rates diversity in morphologically complex lakes.