Sedimentary record for the project aims will be obtained from the High Tatras Lakes using a swimming platform. Drilling site will be selected after a lake sonar survey, which provides high resolution 2D acoustic image on sedimentary infill. This allows a selection of the site with the highest thickness of the sediment. Drilling will be realized by steel hydraulic corer allowing to get 2m long core. Sedimentary cores will be transported to Earth Science Institute in Banská Bystrica and deposited under stable climatic conditions.
It will be used to determine the internal structure of the sediment and the distribution of macrofossils in the cores before cutting. For this purpose, microfocal tomograph v|tome|x L 240 will be used (for a detailed description of the devices see. 240 kV tube will be used, which is suitable for larger and more massive samples.
A sedimentary analysis will define the principal attributes of the sediment (sedimentary structure, texture, composition, macrofossil rests and fossil tracks, color, lithification of the deposit), important for a definition of the paleoenvironment and interpretation of the paleobiological and geochemical data. This information will be used for identification of depositional processes which could influence the proxies at the time of deposition.
Among the water meiofauna used in the paleolimnological studies, subfossil remnants of the Ostracoda and Chironomidae will be used. Both taxonomic groups are rich in species with different habitat requirements, therefore analysis of fossil remnants is used for a reconstruction of a number of environmental parameters such as water temperature, salt concentration, pH, nutrients, bathymetry, the O2 content in the hypolimnion, width of the littoral, water levels changes or changes in predator-prey system. In addition to the species composition, carbonate and chitin carapaces will be used for isotope analysis, which will provide information on habitat composition and community trophic structure (Reuss et al. 2013, 2014). Analysis of chironomid associations will be performed by conventional methods (eg. Smol et al. 2001a, b), some of which have already been used in our research (Bitušík et al. 2009).
Pollen analysis is very valuable paleoclimate proxy and it was used for paleoenvironmental reconstructions of the High Tatras landscape (see Rybníček and Rybníčková 2006). In this paper, pollen analysis will be used as a proxy to identify changes in plant communities at the transition from clay (glacial) and to organic (post-glacial) sedimentation.
Geochemical and mineralogical methods
The carbon content (TOC, TIC, TC, CaCO3) will be analysed as % of loss on ignition (LOI%). C content reflects a content of organic carbon (TOC), and carbonate minerals in the sediment. These analyses will be performed on ESI of SAS. Suitability of LOI for the determination of C will be controlled by direct analyses (eg. TOC, TC, XRD).
Organic sediment extracts will be acquired and further be analysed for molecular and isotope composition of fossil lipids. Their composition should reflect: build-up of soil cover of deglaciated area (cadalene, simonellite, humics); onset of forest (nonacosan-10-ol and conifer terpenoids retene, abietane, pimarates); temperature variations (n-alkane isotope composition of hydrogen); rainwater isotope composition (tentative use of UK37 alkenone proxy). Multivariate statistics on biomarkers may show vegetation changes and oscillations of timberline around given lake.
Stable isotopes provide the most valuable information for paleolimnological and paleoclimatic studies. Carbon and nitrogen isotopes in chironomid head capsules and other insects reflect trophic level and its foraging strategies. Carbon in carbonate shells (e.g. Ostracoda) comes from atmosphere or soil CO2 in various proportion depending on thickness of soil cover and intensity of its respiration. Oxygen isotopes (of carbonate or chitin) depend on isotope composition of water and present a proxy to composition of precipitation, its temperature and source areas.
Mineral composition of sediment and its variations will be quantified using Raman microspectroscopy in sections of sedimentary cores. The instrument Labram HR 800 has a spatial resolution of 1 micrometer and use of motorized XYZ stage allows it to acquire line scans or spectral maps. The method does not require any special sample preparation. Graphic representation of mineral composition will be the basis of a mathematical expression of cyclicity and trends in climate change.
Non-destructive method for detection of elements since Al to U. Elemental composition will be analysed in situ on cut halves of sediment cores using micro-XRF spectroscopy. The incident X-rays are focused to a spot 20 micrometres in diameter, which defines its spatial resolution and yields a very bright secondary signal. Analysis under vacuum allows for good sensitivity even for low mass elements. Using motorized stage the cores will be scanned in line scans or elemental maps. A graphical presentation of element content will be a basis for consideration on climate cyclicity and trends.
Clay minerals originate in soil and their mineralogical composition reflects weathering climatic conditions. For identification, comparison and quantification of clay minerals from sedimentary records, the samples from lake surrounding will be taken and analyse under X-ray powder diffractometer. Clay mineral composition will support stabile isotope analysis and paleobiological proxies.
Radiocarbon dating C14
This is a basic method for age determination of the quaternary sedimentary rock, depth-age model design of the lake and determination of the stratigraphical position of the observed events. Plant remains (needles, leaves, wood) preserved in the deposit will be used for dating on the mass spectrometer (AMS) in Sweden or in the USA.
Mathematic and Statistic methods
First, we will transform data sets provided by quantitative sample analyses to time series and store them in data centre. Second, we will analyse time series with the aim of identifying climatic change, i.e. period with high signal to noise ratio, and cyclicity, i.e. periods with repeated pattern. We will apply standard time series analysis methods, e.g. spectral analysis, state space models, as well as will less known methods, e.g. fuzzy inferential systems. We will interpolate missing parts in time series using for example linear interpolation and regression methods. Finally, we will conduct a pairwise comparison of obtained time series, as well as known time series from the literature. We selected methods of analysis with respect to the well-established methodologies in the research area we are focusing on (eg. Rial 2004; Serefiddin et al. 2004; Fairchild et al. 2006; Cronin 2010). Moreover, we took into account existing implementations of these methods in mathematical and statistical packages disposable for our research team. We will use mainly open source systems R and Octave for our analyses.
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Cohen A.S., 2003. Paleolimnology, The History and Evolution of Lake Systems. Oxford University Press, Oxford-New York, 500 pp.
Cronin Th. M., 2010. Paleoclimates – Understanding Climate Change Past and Present. Columbia Unoversity Press. New York, 441 pp.
Reuss N.S., Hamerlík L., Velle G., Michelsen A., Pedersen O., Brodersen K.P. 2013. Limnology and Oceanography, 58, 1023-1034.
Reuss N.S., Hamerlík L., Velle G., Michelsen A., Pedersen O. & Brodersen K.P. 2014. Hydrobiologia, 730, 59-77
Fairchild I.J., Smith C.L., Baker A., Fuller L., Spotl Ch., Mattey D., McDermott F., E.I.M.F., 2006. Earth-Science Reviews, 75, 105-153.
Rial J.A., 2004. Global and Planetary Change, 41, 81-93.
Rybníčková E., Rybníček K., 2006. Vegetation History and Archaeobotany, 15, 345-356.
Serefiddin F., Schwarcz H.P., Ford D.C., Baldwin S., 2004. Palaeogeography, Palaeoclimatology, Palaeoecology 203, 1-17
Smol J.P., Birks H.J.B., Last W.M. (eds), 2001a. Tracking environmental change using lake sediments. Volume 3 Terrestrial, algal and siliceous indicators. Kluwer Academic Publishers, Dordrecht, 371 pp.
Smol J.P., Birks H.J.B., Last W.M. (eds), 2001b. Tracking environmental change using lake sediments. Volume 4 Zoological indicators. Kluwer Academic Publishers, Dordrecht, 217 pp.