Katalin Hubay

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Papers by Katalin Hubay

Age determination and dust flux of peat core MOHOS

High-resolution multi-proxy reconstruction of Lake Ighiel (Western Carpathians, Romania): processes and controlling factors of lacustrine dynamics during the mid and late Holocene

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An improved chronology for the Lateglacial palaeoenvironmental record of Lake Haemelsee, Germany: challenges for independent site comparisons

Multi-method chronological investigation of a Middle Paleolithic stratigraphic context in Eastern Transylvania, Romania

Paleoenvironmental History of the Retezat Mountains (Southern Carpathians) Inferred from Geochemical Data

Reconstruction of paleoenvironmental changes using geochemical data from South Carpathian Mountains

&lt;p&gt;This study applied bulk sediment geochemistry to reconstruct lateglacial and ear... more &lt;p&gt;This study applied bulk sediment geochemistry to reconstruct lateglacial and early Holocene climatic changes in a glacial lakes (Lake Brazi, 1740 m a.s.l. and Lake Lia, 1910 m a.s.l.) in the Retezat Mts. (South Carpathians, Romania). We studied how the changes of chemical element concentration in the sediment can indicate environmental changes, climate variations and human effects. Our aim was to develop analytical methods, which may complement the methodology of routinely applied paleoenvironmental methods and can be used to identify environmental changes in the past and help us reconstruct local and regional processes.&lt;/p&gt; &lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; In the Retezat Mts., Southern Carpathians, more than hundred glacial lakes were formed after the last glaciation. These glacial lakes are paleoecologically significant because they are characterized by continuous sedimentation since their origin to the present.&lt;/p&gt; &lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; In 2007 and 2008 continuous undisturbed sediment cores were obtained from Lake Brazi and Lake Lia in the Retezat Mts. (Southern Carpathians, Romania) with Livingstone and modified Kullenberg corers. The lowermost part of the sediment cores, covering the period between 9900 and 15 800 cal yr BP, was used for high resolution bulk analysis of major elements (Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, SiO&lt;sub&gt;2&lt;/sub&gt;, TiO&lt;sub&gt;2&lt;/sub&gt;, CaO, MgO, K&lt;sub&gt;2&lt;/sub&gt;O, Na&lt;sub&gt;2&lt;/sub&gt;O, Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; and MnO). Linear discriminant analysis (LDA) was used to compare a priori classified main chemical groups. Subsamples from the core were priory ordered to &amp;#8220;warm&amp;#8221; and &amp;#8220;cold&amp;#8221; groups respectively, according to their age and evidence of cold and warm events in the record, as suggested by proxy correlation with the lateglacial event stratigraphy of North Greenland Ice Core Project (NGRIP). The discriminant function was calculated using concentration of major elements after log ratio transformation. Loss-on-ignition and silicon concentration were not used for the discriminant analysis, but regarded as comparison proxies for checking up the validity of outputs.&lt;/p&gt; &lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; The calculated discriminant values are good indicators of changes in sediment caused by climate change, as their values give the cold and warm directions. The &amp;#8220;a posteriori&amp;#8221; groups can be used to determine the period during which local changes differed from the climate changes in the North Atlantic region. The chemical composition of sediments deposited during the &amp;#8220;cold&amp;#8221; and &amp;#8220;warm&amp;#8221; periods shows differences in both sediments. The discriminant scores showed strong correlation with the NGRIP d&lt;sup&gt;18&lt;/sup&gt;O data and with the pollen percentage sum of trees and shrubs.&lt;/p&gt; &lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Discriminant analyses of bulk sediment major oxide chemical data may be a useful tool to identify the impact of climate events upon the nature and composition of materials delivered to a lake basin.&lt;/p&gt; &lt;p&gt;Key words: climate reconstruction, sediment geochemistry, Retezat Mts.&lt;/p&gt;

Dating of pollen samples from the sediment core of Lake St Anne in the East Carpathian Mountains, Romania

Chronology and inorganic geochemistry of four sediment sequences from the Retezat Mts, South Carpathians (Romania)

GEOREVIEW: Scientific Annals of Stefan cel Mare University of Suceava. Geography Series, 2016

In the frame of PROLONG ( Providing long environmental records of Late Quaternary climatic oscill... more In the frame of PROLONG ( Providing long environmental records of Late Quaternary climatic oscillations in the Retezat Mountains ) project lake sediment records were studied to reconstruct climate changes in the Southern Carpathians. During 2007 and 2008 summer long sediment cores were obtained from four glacial lakes (Lia, Bukura, Gales and Brazi) in the Retezat Mts (Southern Carpathians, Romania). Here we report the chronology and inorganic geochemistry from these lakes

Preliminary stable isotope results from the Mohos peat bog, East-Carpathians

Gas Ion Source Performance of the Environmicadas at Hekal Laboratory, Debrecen, Hungary

A coupled accelerator mass spectrometer–gas interface system has been successfully operating at t... more A coupled accelerator mass spectrometer–gas interface system has been successfully operating at the Hertelendi Laboratory of Environmental Studies, Debrecen, Hungary, since 2013. Over the last 6 years more than 500 gas targets were measured below 100 µg carbon content for carbon isotopic composition. The system was tested with blanks, OxII, IAEA-C1, IAEA-C2, and IAEA-C7 standards. The performance of our instrumentation shows good agreement with other published gas-interface system data and also shows a quite good agreement with the nominal value of international standard samples. There is a measurable but quite small memory effect after modern samples, but this does not significantly affect the final results. Typical ion currents at the low energy side were between 10–15 µA with a 5% CO2 in He mixing ratio. The relative errors average ±6% for samples greater than or equal to 10 µgC sample with mean count rates of 300 counts per microgram C for OxII. The blank is comparable with othe...

Holtmedrek toxikus elemtartalmának vizsgálata üledékminták alapján

Környezetváltozások rekonstrukciója tavak és lápok üledékének vizsgálatával

(Figure 3) Dust flux determined from peat core MOHOS in the Eastern Carpathians, Romania

Holocene paleoclimate inferred from stable isotope (δ18O and δ13C) values in Sphagnum cellulose, Mohos peat bog, Romania

Journal of Paleolimnology

We measured stable isotopes (δ18O and δ13C) in Sphagnum cellulose that was extracted from a long ... more We measured stable isotopes (δ18O and δ13C) in Sphagnum cellulose that was extracted from a long peat core drilled in the ombrotrophic Mohos peat bog, Ciomadul Mountain, Romania. The 10-m-long peat profile spans the period from 11,800 cal yr BP to present. The δ18O and δ13C data indicate there were several cooling events and warm periods in the area of the Mohos peat bog during the Holocene. The 8.2-ka cold event, however, was not detected using δ18O and δ13C values. Response of the peat bog to changing environmental conditions was inferred using data on organic matter accumulation, independent of the stable isotope results. All cool periods during the Holocene, whether of short or long duration, were identified as times of reduced organic matter accumulation rate. Similarly, dry periods were also correlated with reduced accumulation rates of organic matter.

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EnvironMICADAS C-14 AMS Gas ion source performance and its applications at HEKAL Laboratory, Debrecen, Hungary

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Reconstruction of a floodplain area over the last 40.000 years (Tisza river, Hungary) – comparative case study of 14C and OSL methods

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Paleoclimate reconstruction and mire development in the Eastern Great Hungarian Plain for the last 20,000 years

Review of Palaeobotany and Palynology

Abstract We present the reconstruction of mire vegetation changes and fire history recorded in a ... more Abstract We present the reconstruction of mire vegetation changes and fire history recorded in a continuous sediment profile that spans the last 20,000 cal yr BP from the Late Pleniglacial to Holocene in North-eastern Hungary. We also aimed to reveal past climate changes by using ecological requirements of specific aquatic plants as summer temperature indicators. Our results suggest the formation of a mesotrophic mire around 20,000 cal yr BP with brown moss, Betula sp. and Selaginella selaginoides cover beside the occurrence of Phragmites australis, Typha latifolia and T. angustifolia suggesting base-rich fen and tundra-like wet-ground habitats on the lakeshore. This community shifted to reed dominated swamp at c. 18,300 cal yr BP with inferred min. July temperatures of 12–15.7 °C. pinus sp., Betula nana, B. pendula/pubescens, Hippuris vulgaris and P. australis dominated until 16,600 cal yr BP pointing to shallow muddy stagnant water and colder climatic conditions than in the preceding interval. The most warmth-demanding species, T. latifolia and T. angustifolia indicated July mean temperatures > 14–15.7 °C soon after the LGM. The formation of biogenic carbonate also started at an early stage; major accumulation occurred between 15,200 and 10,000 cal yr BP. In the Early Holocene, environmental indicator species (e.g., Phragmites australis and T. latifolia) pointed to warmer and shallower conditions, while the late Holocene was characterized by strong eutrophication and reed swamp dominance on the lakeshore. Elevated macrocharcoal concentration, wood fragments and remains of Typha species suggested frequent local fires and dry mire surface conditions during the last 1700 years.

Holocene environmental changes as recorded in the geochemistry of glacial lake sediments from Retezat Mountains, South Carpathians

Quaternary International

Abstract Sediment cores obtained from two deep (>15 m) glacial lakes were analyzed in context ... more Abstract Sediment cores obtained from two deep (>15 m) glacial lakes were analyzed in context of terrestrial vegetation development and in-lake processes from the Retezat Mountains (Southern Carpathians, Romania). Only the Holocene parts were chosen for study for testing what is the connection between geochemical changes and biotas around and in the lakes. The lakes are situated at slightly different altitudes on the northern (Lake Gales, 1990 m a.s.l.) and southern slope (Lake Bucura, 2040 m a.s.l.), respectively. Changes in geochemical composition were relatively low amplitude during the studied period (10,300–1790 and 10,300–695 cal yr BP) in both lakes, but the applicability of enrichment factor (EF) for geochemical elements and diatom ecological traits (guilds) in paleoecological reconstruction were demonstrated in this paper. The main changes have been observed at ca. 10,670–9000, 6500 and 3100 cal yr BP in geochemistry, vegetation and siliceous algal assemblages. Catchment soil stabilization was apparent from ∼9000 cal yr BP onwards, in-lake and terrestrial productivity was the highest between 9000 and 6500 cal yr BP and human impact became the dominant driver in both terrestrial vegetation and sediment geochemical changes and in-lake processes over the last ∼3400 years in both lakes. The geochemical record displayed frequent erosional events within the Holocene. The strongest soil erosions clustered around 6500–7400 and 3200-900 cal yr BP.

Adoption and Evaluation of a sample Pretreatment Protocol for Radiocarbon Dating of Cremated Bones at HEKAL

Radiocarbon

ABSTRACTA comparative study was undertaken to adopt and evaluate a radiocarbon (14C) preparation ... more ABSTRACTA comparative study was undertaken to adopt and evaluate a radiocarbon (14C) preparation procedure for accelerator mass spectrometry (AMS) measurements of cremated bones at our laboratory, including different types of archaeological samples (cremated bone, bone, charcoal, charred grain). All 14C analyses were performed using the EnvironMICADAS AMS instrument at the Hertelendi Laboratory of Environmental Studies (HEKAL) and the ancillary analyses were also performed at the Institute for Nuclear Research (ATOMKI). After the physical and chemical cleaning of cremated bones, CO2 was extracted by acid hydrolysis followed by sealed-tube graphitization and 14C measurement. The supplementary δ13C measurements were also performed on CO2 gas while FTIR was measured on the powder fraction. Based on the FTIR and 14C analyses, our chemical pretreatment protocol was successful in removing contamination from the samples. Good reproducibility was obtained for the 0.2–0.3 mm fraction of blin...

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High-Resolution Peat Core Chronology Covering the Last 12 KYR Applying an Improved Peat Bog Sampling

Radiocarbon

ABSTRACTThis work focuses on building a high-resolution age-depth model for quantitative palaeocl... more ABSTRACTThis work focuses on building a high-resolution age-depth model for quantitative palaeoclimate study from the Mohos peat bog, East Carpathian mountains. The investigated core presents a continuous peat profile for the last 12 kyr. The chronology was based on 36 accelerator mass spectrometry radiocarbon (AMS 14C) analyses of the separated Sphagnum samples from different depths of the profile. Dry Sphagnum samples for AMS dating were prepared using the classic acid-base-acid (ABA) method followed with an oxidative bleaching step to get clean cellulose. Sphagnum cellulose samples were measured by AMS using the EnvironMICADAS at the ICER (Debrecen, Hungary). A high-resolution chronology was obtained with the use of Bayesian age-depth modeling. Peat accumulation rate has been calculated and the sections with variable accumulation rate values were observed along the profile.

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