Volume 36 (2010): Issue -1 (January 2010)

Two chemical treatments for lead-210 measurement were compared on the sub-surface samples of a core from an ombrotrophic bog from East Belgium. The classical procedure involves a concentrated acid extraction of polonium. However, this treatment represents substantial health risks together with unknowns regarding both the degree of cleanliness and the Po extraction rate, and most importantly, is rather time consuming. We developed here an improved procedure involving an ashing step prior to acid extraction. This allows substantial improvements such as: 1/ the use of a relatively small amount of acid compared to the classical procedure and 2/ the substantial reduction of a total sample digestion time. Measurements of ²¹⁰Pb concentrations were conducted by alpha spectrometry. Results show a good agreement of unsupported ²¹⁰Pb activity obtained for both procedures, although some unknowns remain concerning the adsorption of ²¹⁰Po on the plastic test tube, the volatilization of a small amount of ash, or the absorption of alpha particle at the alpha source surface. This however should not affect the ²¹⁰Pb measurement as all the samples are spiked prior to ashing (i.e. the recoveries are fully monitored). Through this study, we are suggesting researchers to follow this new procedure in order to increase safety, cleanliness, better recovery and substantial time gain.

The research was conducted in selected spruce stands of the Silesian Beskids aged over 70 at altitudes from 403 m a.s.l. to 794 m a.s.l. in 2008. The samples were taken and processed in compliance with standard dendrochronological methodology. Tree rings were measured and the tree-ring curves were synchronized using the PAST4 application. The age trend was removed in the ARSTAN application and the climatic influences were modelled in the DendroClim application. The regional standard tree-ring chronology shows an obvious decrease in the radial increment from the beginning of the 1970s to the mid-1990s. The gradual increase in radial increment which followed in the second half of the 1990s was interrupted in 2000, 2003, and 2006. Most of the years with the decreased radial increment have been confirmed by the analysis of significant negative years. The radial increment statistically significantly correlates with the precipitation in July and September of the previous year, precipitation in June of the year in question and precipitation during the vegetation period. Moreover, the growth of spruce is statistically significantly affected by temperatures in October of the previous year and March of the year in question. Additionally, the paper includes habitual monitoring of trees and the volume of salvage cutting in these districts. The condition of the habit of trees and the development of salvage cuttings agree with the hypothesis about strong stress load or its considerable increase in 2003 and the following years.

Seven different tree-ring parameters (total tree-ring width, earlywood width, latewood width, maximum latewood density, minimum earlywood density, average earlywood density, and average latewood density) were obtained from Schrenk spruce in the Urumqi River Basin, China. The chronologies were analyzed individually and then compared with each other. The relationships between the different tree-ring parameters and climate data (Daxigou) are also presented. Earlywood-related parameters (earlywood width, minimum density, and earlywood density) were more sensitive to climate than those of latewood. Temperature (July) was found to be the most strongly related to the earlywood density. Based on the results of climate response analysis, the potential of tree-ring chronologies from this species to provide climate reconstructions in the Urumqi River Basin has been established. This study demonstrates that the use of tree-ring density data can increase the climate information obtained from tree-ring and should lead to improved paleoclimate reconstructions in Central Asian.

The study presents a proposal of application of the statistical permutation test, known from other applications, for searching for the symptoms of cyclicity, in particular related to solar activity, in the annual growth sequences of trees. The test consists in generation of random sequences of the increment widths observed and comparison of their periodograms with the periodogram of the sequence analysed. This allows for evaluation of the significance of the individual frequencies in the total variability. The model calculations carried out indicate that in the studies on cyclicity in dendrochronological sequences satisfactory results could be obtained in the analysis of sets of the individual sequences (but not the chronologies produced from them). It is important to generate sufficiently high numbers (1000 and more) of random sequences and to apply relatively low significance levels (at 0.05, or even 0.01).

Lodowa Cave in Ciemniak, which belongs to the dynamic ice cave type, contains the biggest perennial block of cave-ice in the Tatra Mountains. The ice represents congelation type, since it originates from freezing of water which infiltrates the cave. Two generations of ice have been recognized in this cave. They are divided by the distinct unconformity. The ice building both generations is layered. Two moths which were found in the younger generations were sampled and dated by ¹⁴C method yielding 195 ± 30 and 125 ± 30 years. Bearing in mind the position in the section and the fact that the cave ice has waned since the 20s of the last century, the age is 1720-1820 AD and 1660-1790 AD respectively. It proves that the ice was formed during the Little Ice Age. Hence, the erosion boundary which underlies this generation records the degradation of ice before the Little Ice Age most probably during the Medieval Warm Period. The ice volume in the cave was substantially smaller before the Little Ice Age than it is today, despite the clear tendency to melting, which has been recognized since 20s of the last century. The older generation of ice is supposed to have its origins in a cold stage between the Atlantic period and the Medieval Warm Period.

In this paper we report the results of interdisciplinary investigations of deposits filling small closed depressions in the Western Polesie region. There were reconstructed the environmental changes and the main evolution phases of four morphometrically similar forms (=research sites) situated in the Lublin and Volhynia parts of the Polesie region. The gathered sedimentological, chronostratigraphical, palynological and geochemical data evidence great lithological (peats, gyttja, calcareous tufa) and age (Late Glacial, Neoholocene) differences between the deposits filling individual forms and indirectly suggest their karstic origin.

The study of the deglaciation chronology in the south-eastern Baltic Region belonging to the outer zone of the last Pleistocene glaciation has a long history. The Finnish investigator H. Hausen (1913) who worked in the north-western portion of the East-European Plain at the beginning of the 20^th century was the first to attempt a reconstruction of the course of glacial retreat during the last glaciation. At that time investigators had no physical dating methods and the time scale based on varvometric method, introduced by the Swedish geologist G. de Geer (1912) who divided the deglaciation history of Scandinavia into Daniglacial, Gotiglacial and Finiglacial, each of which had different palaeoglaciological conditions. During last decades different dating methods, including ¹⁴C, ESR, luminescence methods and ¹⁰Be techniques have been used, but they could not help essentially improve the existing stratigraphical charts and many problems of topical interest in the history of deglaciation have not been solved yet. During last years the first two authors have studied the suitability of OSL method for the geochronological purposes, paying the most attention to the waterlaid sediments. In the first step they have found the most promising genetical varieties of glaciofluvial sediments (glaciofluvial deltas and sandurs) and in this paper they widened the study area to all three Baltic states with close cooperation with Latvian and Lithuanian colleagues. The obtained results demonstrated, that not all mineral grains in the uppermost glaciofluvial and glaciolacustrine sediments were fully bleached during the last deglaciation. Probably the older sediments also influenced to the luminescence results. It means, that stratigraphic conclusions based on single dates or their small sets are inadmissible and in each case luminiscence dating requires a verification using other methods.