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1

Radiocarbon dated pulse and cereal crops indicate diachronic use of Iron age extreme upland sites in the Western Carpathians, Slovakia

Barta Peter, Hajnalová Mária, Benediková Lucia, Dreslerová Dagmar, Pieta Karol

Geochronometria

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2023

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Vol. 50, no. 1

1--20

EN

Mountain summits in the Slovak part of the Western Carpathians bear evidence of human presence from the Late Bronze to the Late Iron Age. According to fire-induced changes in archaeological record and finds of weaponry, some of the extreme upland sites (EUS) were viewed as places of safety or refugia violently destroyed within a short period. We have focussed on three sites with summits at 1300–1550 m a. s. l. and found out that two of them were used in 650–400 calBC and 390–150 calBC, respectively. By the first systematic use of 14C dating and targeted 14C sampling, we have overcome the inherent chronological imprecision of their artefactual record and opened new vistas for interpretation of this type of sites.

2

Calibrated geochemical ages of the Baltic Artesian Basin groundwater

Samalavičius Vytautas, Arustienė Jurga

Geologos

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2022

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Vol. 28, No. 3

179--189

EN

For the present study, geochemical ages were derived from radiocarbon and radiokrypton age calibration with ground-water chemical contents (Na+, K+, Mg2+, Ca2+, Cl−, SO42−, HCO3−). Geochemical ages may fill the dating gap (40–150 ka) between the isotope techniques mentioned. A case study of groundwater in the Baltic Artesian Basin has involved geochemical age calibration, data filtering (such as regional subdivision of the basin for more accurate results) and geochemical dating of groundwater of unknown age. Various approaches to interpretations of geochemical age results could be used. Bicarbonate and sulphate are sensitive to the hydrochemical environment and should be omitted from geochemical age calculations. Modern fresh groundwater samples should also be excluded from calibration in order to obtain more reliable trend lines. Calcium-sodium cation exchange occurs in deep aquifers and may be used for geo- chemical age determination of fossil groundwater.

3

Coastal dune dynamics along the northern Curonian Spit, Lithuania : toward an integrated database

Bitinas A., Dobrotin N., Buynevich I. V., Molodkov A., Damušytė A., Pupienis D.

Geological Quarterly

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2018

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Vol. 62, No. 3

553--562

EN

Sand dunes are the most prominent subjects of geological and geomorphological interest along the Curonian Spit - a mega-barrier that separates the Curonian Lagoon from the Baltic Sea. To date, an assessment of various parameters of migrating dunes along the spit has been based on comparative analysis of old maps or aerial and satellite images, as well as geodetic measurements. These investigations have allowed assessment of dune dynamics over a relatively short historical period (~1700s to present). The most recent detailed investigations of the Dead (Grey) Dunes along the Lithuanian part of the spit using ground-penetrating radar (GPR) and magnetic susceptibility (MS) surveys, supported by a radiocarbon (14C) chronological framework of palaeosols and infrared optically stimulated luminescence (IR-OSL) ages of sand horizons, have advanced our understanding of aeolian landscape evolution. The interpretation of dune activity and stability phases has been generally based on IR-OSL dating results of the sand layers located between radiocarbon-dated palaeosols. However, the influence of soil-forming processes on the IR-OSL dating results related to possible migration of natural radioactive isotopes via aeolian sand layers has not been previously considered. Hypotheses of dune reactivation and migration caused by abrupt regional climate shifts, catastrophic forest fires, anthropogenic influence, and more local forcings have been tested. An integrated approach to dune investigations has offered an estimate of the rates of sand accumulation and key phases of aeolian dynamics during both stormy and calm periods, as well as helped to extend the record of dune evolution to the mid-Holocene. The palaeoenvironmental and palaeodynamic reconstructions of the Dead Dunes suggest that this mid-Holocene phase of dune activity was of a local character and likely did not exceed several centuries.

4

Method validation for the determination of fraction of modern (F14C) in wood samples using conventional method

Baydoun R., El Samad O., Nsouli B., Younes G.

Geochronometria

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2018

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Vol. 45, no. 1

68--73

EN

The radiocarbon laboratory at the Lebanese Atomic Energy Commission is undertaking environmental studies, in order to determine the anthropogenic impact of technologies on the ecosystem through the determination of radiocarbon content in tree leaves and plants. Thus, it was important to validate the method used to demonstrate that the applied procedure gives reliable results. Method validation is universally applied in analytical laboratories as an essential part of quality assurance system and as a basic technical requirement of the ISO 17025 standard. The conventional method used for determination of Fraction Modern (F14C) is a standard method issued by the American Society for Testing and Materials in 2011 with a code ASTM-D 6866-11 Method C. According to Eurachem guide, internal validation was expressed in terms of accuracy that was evaluated by trueness and precision. Trueness was expressed in terms of relative bias, while for precision ten consecutive replicates were carried out to under repeatability conditions and five duplicates were analyzed under reproducibility conditions. The limit of detection and the minimum detectable activity (MDA) were calculated. Uncertainty sources were defined and their relative standard uncertainties were calculated in order to determine the combined standard uncertainty. Five reference samples of different matrices were analyzed; calculated z score values were acceptable as being between –2 and +2. The calculation and results are presented in this work.

5

Badania izotopowe wody dopływającej do poprzeczni Mina na poz. IV Kopalni Soli „Wieliczka” wykonane w latach 1991-2007: wyniki i ich interpr etacja

Duliński M., Brudnik K.

Przegląd Solny

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2017

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T. 13

24--34

PL

Badania izotopowe wycieku w poprzeczni Mina (W IV- 27) na IV poziomie kopalni soli „Wieliczka” zapoczątkowano w październiku 1991 roku i prowadzono nieprzerwanie do momentu likwidacji wycieku w październiku 2007 roku. Rutynowo obejmowały one analizy składu izotopowego wody (d18O, d2H) i stężenia trytu. Trzykrotnie wykonano oznaczenia składu izotopowego węgla (d13C) oraz aktywności radiowęgla (14C) w rozpuszczonych węglanach. Badania składu izotopowego początkowo wskazywały na dopływ do wycieku wód zasilanych w chłodniejszych warunkach klimatycznych w stosunku do panujących obecnie, lub zdominowanych przez takie wody (tzw. wody „glacjalne”). Z biegiem czasu skład izotopowy uległ przesunięciu w kierunku składu wód współczesnej infiltracji. W całym okresie obserwacji skład izotopowy wykazywał znaczące fluktuacje, potwierdzające złożoność warunków hydrogeologicznych w sąsiedztwie wycieku, stwierdzonych w oparciu o badania znacznikowe na przedpolu poprzeczni Mina. W latach 1991-2007 wykonano łącznie 35 oznaczeń stężenia trytu w wodzie z wycieku. Ich rezultaty stały się podstawą do próby zastosowania modeli komorowych w celu określenia warunków i parametrów przepływu wody przy użyciu programu FLOWPC. Dokładny wgląd w dynamikę dopływu wód do poprzeczni oraz w strukturę danych izotopowych, wraz z postępującym rozwojem wiedzy na temat warunków przepływu wód podziemnych w obszarze zbiornika GZWP-451 zmusił do rewizji poglądów na temat interpretacji danych izotopowych. W latach 1992, 1993 i 2004 wykonano analizy składu izotopowego węgla d13C oraz aktywności 14C w rozpuszczonych węglanach pochodzenia nieorganicznego. Aktywność 14C systematycznie rosła, świadcząc o dopływie do wycieku coraz młodszej wody. Skład izotopowy węgla odzwierciedlał wartości mieszczące się w przedziałach typowych dla układów węglanowych formowanych przy udziale glebowego CO2, zmodyfikowanych w wyniku procesów rozkładu martwej materii organicznej. W prezentowanej pracy zestawiono wszystkie wyniki analiz izotopowych wykonane na przestrzeni lat 1991-2007 dla wycieku W IV-27 w poprzeczni Mina. Przedstawiona interpretacja wyników jest podsumowaniem i zwieńczeniem prac związanych z tym wyciekiem.

EN

Isotope investigations of water inflow to the Mina crosswise (W IV-27) located at the level IV of the „Wieliczka” salt mine started in October 1991. They were conducted regularly until October 2007, when the leak was stopped completely. Routine measurements included analyses of oxygen and hydrogen stable isotope composition of water (d18O, d2H) and tritium concentration. Three analyses of d13C and 14C in total dissolved inorganic carbon had been performed during the lifetime of the inflow. Initially, stable isotope composition of water indicated presence of water recharged in colder climate when compared to present-day conditions. Over time, this composition shifted towards the values typical for waters of modern infiltration. Over the entire period of observations the isotopic composition of inflowing water revealed significant fluctuations, indicating complexity of hydrogeological conditions in the vicinity of the Mina crosswise. During the period 1991 – 2007, a total of 35 determinations of tritium content had been made. Tritium data were used in numerical modeling of flow conditions using lumped parameter models (FLOWPC code). Detailed considerations of the dynamics of the inflow and the structure of isotope data forced the revision of previous interpretation. Analyses of 13C and 14C content in the total dissolved inorganic carbon pool were performed in 1992, 1993 and 2004. Activity of 14C has been increasing over this time period, indicating gradual freshening of the inflow. Stable carbon isotope composition (d13C) reflected values typical for carbonate solutions formed with participation of soil CO2, modified by processes of the dead organic matter decomposition. In a paper results of all isotope analyses performed during the existence of inflow to the Mina crosswise are presented and their new interpretation is proposed.

6

Określanie wieku wód podziemnych z wykorzystaniem izotopów środowiska – uwagi metodyczne

Duliński M., Różański K., Gorczyca Z., Marzec M.

Przegląd Geologiczny

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2017

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Vol. 65, nr 11/1

1049--1054

EN

Groundwater age plays an important role in both development and management of groundwater resources. This is particularly true for groundwater systems being exploitedfor drinking water purposes and subject to anthropogenic stress. Environmental isotopes play a vital role in quantifying time scales of groundwater flow, ranging from fraction of a year to millions of years. Over the past several decades a large number of groundwater age indicators have been proposed. Apart of radioactive isotopes, also stable isotopes of water, isotopes of noble gases and anthropogenic trace substances present in the atmosphere have been usedfor this purpose. This work is focusing on methodological aspects of groundwater age determinations using tritium, radiocarbon and stable isotope composition of water. The discussion is based on a rich material available after several decades of application of environmental isotope techniques in groundwater studies in Poland.

7

Isotope characterisation of deep aquifers in the Gwda catchment, northern Poland

Kotowski T., Satora S.

Geologos

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2016

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Vol. 22, No. 2

137--147

EN

We present the results of isotope measurements (δ18O, δ D, δ13CDIC and 14C) and chemical analyses (TDS, TOC, HCO3–, SO42–, Cl–, NO3–, NH4+, Ca2+, Mg2+ Na+ and K+) conducted on groundwater samples collected from deep Cenozoic aquifers. These aquifers are the basic source of drinking water at numerous localities within the study area in northern Poland. Most of the δ18O determinations are characterised by low variability (i.e., > 70 per cent of δ18O are between –9.5‰ and –9.2‰). In most cases tritium activity was not detected or its content slightly exceeded the uncertainty of measurement (from ±0.3 T.U. to ± 0.5 T.U.). On average, 14C activity is twice higher than that under similar conditions and in hydrogeological systems. The δ13CDIC values fall within the –13.6‰ to –12.8‰ range. A slight variability is observed when considering all isotope and chemical data within the study area and under these hydrogeological conditions. In general, the results of isotope and chemical analyses seem to be homogeneous, indicating the presence of closely similar groundwaters in the system, irrespective of geological formation. It is likely that there is a significant hydraulic connection between shallow and deep aquifers in the Gwda catchment, which indicates the potential for seepage of pollutants from shallow Pleistocene to deep Miocene aquifers. This can endanger the latter by e.g., high concentrations of NO3–, SO42– and Cl– ions from shallow aquifers within the Gwda catchment.

8

Radiocarbon 14C method as useful tool for flue gas monitoring application: review

Stachów M.

Budownictwo i Inżynieria Środowiska

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2016

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Vol. 7, no. 4

247--251

EN

Cosmic-ray research which started just after the second world war in 1947, encouraged widespread use of radioactive particles in many areas of science and technology, starting from astronomy, chemistry, archaeology, biology, botany, medicine and lately ending with environmental studies. Method based on measurements of the radioactive elements remains in various samples (solid, liquid and gaseous) can be very useful tool for ecological and environmental analytical measurements. The 14C liquid scintillating counting method was used for simplified determination of the biomass content in flue gas from combustion processes or in the finished bio-product. Review of the latest results and progress in this research area shows the growth of interest from industrial sector in normalised method for biomass content determination.

9

The applicability of C-14 measurements in the soil gas for the assessment of leakage out of underground carbon dioxide reservoirs

Chałupnik S., Wysocka M.

Nukleonika

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2014

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Vol. 59, No. 1

3--7

EN

Poland, due to the ratification of the Kioto Protocol, is obliged to diminish the emission of greenhouse gases. One of the possible solutions of this problem is CO2 sequestration (CCS – carbon capture and storage). Such an option is a priority in the European Union. On the other hand, CO2 sequestration may be potentially risky in the case of gas leakage from underground reservoirs. The most dangerous event may be a sudden release of the gas onto the surface. Therefore, it is very important to know if there is any escape of CO2 from underground gas reservoirs, created as a result of sequestration. Such information is crucial to ensure safety of the population in areas located above geological reservoirs. It is possible to assess the origin of carbon dioxide, if the measurement of radiocarbon 14C concentration in this gas is done. If CO2 contains no 14C, it means, that the origin of the gas is either geological or the gas has been produced as a result of combustion of fossil fuels, like coal. A lot of efforts are focused on the development of monitoring methods to ensure safety of CO2 sequestration in geological formations. A radiometric method has been tested for such a purpose. The main goal of the investigations was to check the application possibility of such a method. The technique is based on the liquid scintillation counting of samples. The gas sample is at first bubbled through the carbon dioxide adsorbent, afterwards the adsorbent is mixed with a dedicated cocktail and measured in a low-background liquid scintillation spectrometer Quantulus. The described method enables measurements of 14C in mine and soil gas samples.

10

Set-up, optimization and first set of samples at the radiocarbon laboratory in Lebanon

Baydoun R., El Samad O., Aoun M., Nsouli B., Younes G.

Geochronometria

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2014

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Vol. 41, no. 1

87--91

EN

A new radiocarbon laboratory has been established recently at the Lebanese Atomic Ener-gy Commission. This laboratory consists of benzene synthesis line and a low background liquid scin-tillation counter, Tri-Carb 3180 TR/SL for measurements with Bismuth Germanate (BGO) guard de-tector. The effectiveness of the benzene line was tested firstly by preparing benzene from a wood sample after carbide and acetylene receiving. Normalization and standardization of the liquid scintil-lation counter was carried out, as well as the Factor of Merit (E2/B) was determined for three differ-ent counting regions. To assure accuracy and reliability of results, reference materials were used. Based on z-score and u-score evaluation, as well as Student's t-test, acceptable data were obtained from travertine and wood samples available through the International Atomic Energy Agency (IAEA-C2 and IAEA-C5), and humic acid (U) and murex shell (R) from the Fifth International Radiocarbon Intercomparison (VIRI). After that, a preliminary study was done, which is the base for future re-search in order to assess the anthropogenic impact and degree of environmental pollution in terms of radiocarbon isotope ratio (Δ14C) deduced from the Percent Modern Carbon or PMC. This work repre-sents the results of four reference materials and those of five green grass samples. The Δ14C of green grass samples collected from two different clean zones were found to be 50‰ and 52‰, while the values of those collected from different polluted zones were 23‰, 7‰ and 15‰.

11

Radiocarbon and dendrochronological dating of Sub-fossil oaks from Smarhoń riverine sediments

Vitas A., Mažeika J., Petrošius R., Pukienė R.

Geochronometria

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2014

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Vol. 41, no. 2

121-128

EN

Sub-fossil oaks from Smarhoń in Belarus have been investigated and tree-ring chronologies were assembled. According to radiocarbon dating, the oldest oak grew from 5782–5612 cal BC and the youngest from 1575–1747 cal AD. Radiocarbon and dendrochronological dating of 97 samples, four single series, 10 mean curves (containing 2–9 series) and three chronologies (10–25 series) were constructed. The longest chronology (No. 16), covering 549 years, was absolutely dated against various oak chronologies of Polish/Baltic origin to AD 778–1326. Germination and dying-off phases were assessed from the three best replicated chronologies.

12

A lake fortress, a floating chronology, and an atmospheric anomaly: the surprising results of a radiocarbon wiggle-match from Āraiši, Latvia

Meadows J., Zunde M.

Geochronometria

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2014

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Vol. 41, no. 3

223--233

EN

An Iron Age timber settlement which, in view of the defensive structures uncovered, is described as a lake fortress, on an island in Lake Āraiši, north-eastern Latvia, was excavated in 1965–69 and 1975–79 by teams led by Jānis Apals, who distinguished five construction phases. Dendrochronological analysis produced a c. 100-year floating chronology for Norway spruce (Picea abies (L.) Karst.) timbers from the earliest phase. A 14C wiggle-match was undertaken to obtain an absolute date range for the final year of the floating chronology, and thus for the construction of the settlement. Ten blocks of wood from one timber, each comprising 6-11 years and collectively spanning the whole 93-year tree-ring series, were dated by AMS. Using the IntCal13 calibration data, there is a 95% probability that the felling date of this timber falls in the range 775–784 cal AD. It appears, however, that the AD 775 spike in the atmospheric 14C level occurred within the 6-year span of the last sample. On this basis, we can narrow the date of construction to 776–780 cal AD. This date is significantly earlier than those reported in previous publications.

13

Peculiarities of sedimentation conditions in the oxbow lakes of Dubysa River (Lithuania)

Gaigalas A., Pazdur A., Michczynski D., Pawlyta J., Kleišmantas A., Melešyte M., Rudnickaite E., Kazakauskas V., Vainorius J.

Geochronometria

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2013

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Vol. 40, no. 1

22-32

EN

Abundant wood remains and buried trees have been found in the western part of Lithuania near Zakeliškiai and Lyduv?nai on Dubysa River (a tributary of Nemunas River) where deposits are rich in organic remnants and buried soils. In Zakeliškiai and Skiručiai sections of Dubysa River ox-bow sediments were investigated by various methods (dendrochronological, carbonate, granulometric, pollen and mollusc fauna analysis). In addition, these sections were dated using the radiocarbon method. Samples were collected from deposits of Dubysa River outcrops. The studied oxbow lakes have existed for more than 5 thousand years (from ca. 4300 BC to 1000 AD). During this period or-ganic rich deposits with trees and branches were formed in the oxbow lake. This indicates that at the end of Atlantic, during Subboreal and in the early Subatlantic periods there was a forest growing that contained mainly oaks which were falling down into an oxbow lake and later were covered by sandy and silty deposits. The granulometry of alluvial deposits, as well as the mixture of medium-grained sand and silt show different stages of Dubysa River palaeochannel formation: riverbed and oxbow lakes. Three climate warming cycles were revealed according to carbonate analysis data in all investi-gated sections. The rheophile thermophilous Holocene age molluscs species Bithynia tentaculata L., Unio cf. crassus Philipsson, Pisidium amnicum (Müller), Theodoxus fluviatilis (Linnaeus) have been found. The pollen composition and sequences have been divided into five local pollen assemblage zones (LPAZ) and described according to pollen spectra in each zone. In this way it is possible restore palaeoclimatic coherent evolution, trends and cyclical change.

14

The feasibility of measurement of radiocarbon in carbon monoxide from coal mines as a potential indicator of mine fires

Luxbacher K., Lindsay C.

Cuprum : czasopismo naukowo-techniczne górnictwa rud

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2012

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nr 2

27-33

EN

The current methods of fire diagnosis for inaccessible areas of coal mines, such as gob are not always definitive. In some cases, it is difficult to determine if incidents involving ignitions or smoldering have evolved into flaming minę fires. A more definitive test for fire could involve monitoring for the existence of radiocarbon -carbon-fourteen (14C) in carbon monoxide (CO). CO is produced by the Iow temperature oxidation of coal; however, since coal is millions of years old, this CO will not have any 14C in it. The only carbon that will have the modern amount of UC in it will be the CO2 that is in the air that is drawn into the mine by the ventilation system. In accordance with the Boudouard Equilibrium, an interchange can take place that converts CO2 to CO, but only at temperatures high enough to be associated with fire. If this interchange takes place, then CO would have 14C in it. The existence of 14C in CO could be a definitive indicator of fire in gob areas. This paper outlines the background associated with this theory and examines preliminary methods for testing for the presence of 14C.

PL

Aktualne metody diagnozowania pożarów w niedostępnych obszarach kopalni węgla, takich jak zroby, nie zawsze są rozstrzygające. W niektórych przypadkach, trudno jest określić, czy wypadki, w których nastąpił zapłon lub tlenie się spowodowały pożar w kopalni. Bardziej rozstrzygające badanie pożaru powinno obejmować monitoring obecności radiowęgla - węgla-14, (14C) w tlenku węgla (CO). Tlenek węgla jest produkowany przy niskotemperaturowym utlenianiu węgla, jednak, skoro węgiel ma miliony lat, tlenek węgla nie będzie zawierał 14C. Jedyny węgiel, który będzie zawierał C z obecnych czasów, będzie to CO2 obecny w powietrzu, które jest wprowadzane do kopalni poprzez system wentylacji. Zgodnie z równowagą Boudouarda może mieć miejsce zamiana, która przekształca CO2 w CO, ale tylko w wysokich temperaturach, które mogą towarzyszyć pożarowi. Jeśli taka zamiana ma miejsce, wtedy CO będzie zawierał 14C. Obecność 14C w CO mogłaby być rozstrzygającym wskaźnikiem pożarów w obszarach zrobów. Artykuł przedstawia w zarysie przesłanki powiązane z tą teorią i analizuje wstępne metody badania obecności 14C.

15

Radiocarbon method in monitoring of fossil fuel emission

Rakowski A. Z.

Geochronometria

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2011

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Vol. 38, no. 4

314-324

EN

The traditional radiocarbon method widely used in archaeology and geology for chronological purposes can also be used in environmental studies. Combustion of fossil fuels like coal, natural gas, petroleum, etc., in industrial and/or heavily urbanized areas, has increased the concentration of carbon dioxide in the atmosphere. The addition of fossil carbon caused changes of carbon isotopic composition, in particular, a definite decrease of 14C concentration in atmospheric CO2 and other car-bon reservoirs (ocean and terrestrial biosphere), known as the Suess effect. Tree rings, leaves, as well as other annual growing plants reflected the changes of radiocarbon concentration in the atmosphere due to processes of photosynthesis and assimilation of carbon from the air. By measuring radiocarbon concentration directly in atmospheric CO2 samples and/or biospheric material growing in industrial and/or highly urbanized areas where high emission of dead carbon is expected, it is possible to estimate the total emission of dead CO2 . Based on equations of mass balance for CO2 concentration, stable isotopic composition of carbon and radiocarbon concentration it is possible to calculate CO2 concentration associated with fossil fuel emission into the atmosphere. The procedure use differences between the radiocarbon concentration and stable isotope composition of carbon observed in clean areas and industrial or/and highly urbanized areas.

16

Combined dating methods applied to building archaeology: the contribution of thermoluminescence to the case of the bell tower of St Martin's church, Angers (France)

Blain S., Guibert P., Prigent D., Lanos P., Oberlin C., Sapin C., Bouvier A., Dufresne P.

Geochronometria

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2011

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Vol. 38, no. 1

55-63

EN

St Martin's church, Angers, is emblematic of the problems raised in pre-12th century history of architecture. In view of the importance of this building, it was necessary to attempt to define its dating and this study particularly focuses on its bell-tower. In addition to the conclusion resulting from the interpretation of written sources and typological criteria positioning the construction of the site at the beginning of the 11th century, not only a significant number of 14C dates were carried out on charcoals from the masonry structures, but also independent dating by archaeomagnetism and thermoluminescence were performed on bricks from the bell-tower. The whole results from these three different methods agree and indicate the lower level of the bell tower was likely built in the 9th century, disputing evidence to the theory of construction in the 11th century of the church. Presented here are the detailed results obtained from the thermoluminescence (TL) dating analysis.

17

Geochemistry and age of groundwater in a hydrochemically diversified aquifer (Permo-Carboniferous, the Intra-Sudetic Synclinorium, SWPoland) derived from geochemical modelling and isotopic studies

Dobrzyński D.

Acta Geologica Polonica

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2009

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Vol. 59, no. 3

371-411

EN

Comprehensive investigations of groundwater were performed in a sedimentary aquifer of Permo-Carboniferous, Intra-Sudetic Synclinorium, in SWPoland. The investigation included aqueous chemical and isotopic composition, chemistry of mineral phases, geochemical modelling, and tritium and radiocarbon groundwater dating. Chemical diversity in the groundwater system is created by the mixing of modern fresh water and older sulphate water with higher dissolved solids. The system is treated as a system of flows of two end-member water types. Geochemical modelling is used for: (1) explaining the origin of the chemistry of both water components, (2) quantifying the groundwater mixing, (3) correcting the radiocarbon age of the groundwater for the effects of chemical water-rock interactions, and (4) calculating reaction rates. Study of stable (C, S, O, H) and unstable ([^3H], [^14]C) isotopes allowed the inverse mass balance geochemical models to be verified and specified, and the groundwater to be dated. The chemistry of the modern, tritium-bearing, fresh water is a result of dissolution of limestones, dolomites and gypsum. The mean tritium-age of this water, based on the lumped-parameter approach, varies between 10 and 200 years. The sulphate mineral water owes its chemistry to the process of dedolomitization driven by gypsum dissolution. Its radiocarbon age is about 5.9 ka BP, i.e., during theMid-Holocene Climatic Optimum. Rates of chemical reactions responsible for the formation of sulphate type water are estimated to be: dissolution of gypsum (2.85 [mi]mol/L/year) and dolomite (0.21 [mi]mol/L/year), calcite precipitation (0.20 [mi]mol/L/year), organic matter decomposition (0.08 [mi]mol/L/year).

18

The Effect of PDF peaks' height increase during calibration of radiocarbon date sets

Michczyński A., Michczyńska D. J.

Geochronometria

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2006

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Vol. 25

1-4

EN

Large sets of dates are often used to construct frequency distributions to investigate variability of some events, which can follow an environmental change (eg. crystallization of speleothems depends on climatic conditions). Examples of such distributions are probability density functions (PDF) created for radiocarbon dates. In order to reach reliable conclusions concerning environmental changes, we should know how to interpret these distributions. In this study, the authors discuss the problem of a possible correlation between the presence of some high, narrow peaks in the probability density function and the shape of the calibration curve.

19

Groups of too close radiocarbon dates

Walanus A.

Geochronometria

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2006

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Vol. 25

5-10

EN

In the archaeological and palaeogeographical literature, it is relatively frequent to find groups of radiocarbon dates of too close values. Too close means here that the dates exhibit no other variability than that of random origin, quantified by the given measurement errors. The chi-squared statistic seems to be appropriate to test, if the given group of dates is of random variability, of larger variability (what is typical) or of too small variability. The last case is hard to explain.

20

Carbon and oxygen isotope composition of organic matter and carbonates in recent lacustrine sediments

Sensuła B., Böttger T., Pazdur A., Piotrowska N., Wagner R.

Geochronometria

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2006

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Vol. 25

77-94

EN

The distribution of stable isotopes (18O and 13C) and radiocarbon in organic materials, carbonates and water samples collected from the environment of lacustrine sediments in Gościąż Lake (Central Poland) and Wigry Lake (NE Poland) were investigated. The oxygen and carbon isotopic analysis of terrestrial semi submerged and submerged plants, shells and water samples were compared with the results of the uppermost sediments from lakes. It was found that the concentration of isotopes in different components of organic and carbonate materials in lakes and their environments are reflected in isotope composition averaging of lakes sediments, whereas the isotope composition of plants and carbonate depends on biogeochemical factors. The research carried out revealed significant variations in the distribution of the stable isotopes and 14C in different elements of lacustrine ecosystem. We have analyzed mean values and variations of 14C concentration, δ18O, δ13C of plants, carbonates and the relationship between the total content of carbon and δ13C. In the case of plants, the isotope composition depends also on the physiognomy and the photosynthesis pathway. We noticed variations in δ13C and δ18O within plant tissues, variations in δ13C among whole tissue material and alphacellulose, carbon isotopic composition of photosynthetically fixed carbon and syntaxonomic dependences and then we compared the results of isotope composition of plants and carbonates in Wigry Lake and Gościąż Lake.