scholarly journals Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development of the Žitný ostrov Island (SW Slovakia)

2010 ◽  
Vol 61 (6) ◽  
pp. 513-533 ◽  
Author(s):  
Peter Pišút ◽  
Eva Břízová ◽  
Tomáš Čejka ◽  
Radovan Pipík
Keyword(s):  
Late Holocene ◽  
Mixed Forest ◽  
Shallow Groundwater ◽  
Alnus Glutinosa ◽  
Danube River ◽  
Oxbow Lake ◽  
Ceratophyllum Demersum ◽  
Atriplex Prostrata ◽  
New Information ◽  
Carex Riparia

Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development of the Žitný ostrov Island (SW Slovakia)Žitný ostrov, the largest island of the Danube River (SW Slovakia) gained its present shape in the Neoholocene period. As a result of increased flood and geomorphological Danube river activity dated to 1378-1528 AD, the Lower Dudváh River was abandoned and its alluvium became a part of the Žitný ostrov. Study of a Dudváh terrestrialized paleomeander by means of pollen and macrofossil analysis provides new information about the paleoenvironments of the Danubian Plain. The meander under study was cut-off during the Sub-Boreal period when the land was mostly covered by oak-dominated mixed forest with a notable high frequency ofFagusandAbies.In low-lying depressions,Alnus glutinosaformed typical alder carrs. The largest decline of the mixed forest occurred during the Sub-Atlantic period. Until the mid-19thcentury the region was strongly influenced by shallow groundwater and periodical floods, as reflected by pollen of aquatics and marsh species. Amongst non-arboreal taxa, pollen of Cyperaceae, Brassicaceae/Cuscuta, Poaceae and Apiaceae prevailed. Local successional changes started with i) stage of abandoned oxbow still with influx of moving water, poor in both macrophytes and molluscs, ii) shallow eutrophic oxbow lake with slowly flowing or stagnant water overgrown with aquatics (Ranunculussubgen.Batrachium, Potamogetonsp.,Ceratophyllum demersumetc.) and abundant molluscs, iii) an open marsh dominated by Cyperaceae (mainlyCarex riparia) withAtriplex prostrata, supporting diverse molluscan and Ostracod fauna. Present-day habitat is a result of landscape changes, which have been associated with draining, intensified agriculture, ruderalisation and spread of invasive species.

Late-Holocene palaeoenvironmental reconstruction from a lake in the Amazon Rainforest-Tropical Savanna (Cerrado) boundary in Brazil using a multi-proxy approach

The Holocene ◽  
2021 ◽  
pp. 095968362110190
Author(s):  
Kury Milena Souza ◽  
Moreira Luciane Silva ◽  
Cordeiro Renato Campello ◽  
Sifeddine Abdelfettah ◽  
Turcq Bruno ◽  
...  
Keyword(s):  
Late Holocene ◽  
Amazon Region ◽  
Amazon Rainforest ◽  
Oxbow Lake ◽  
Tropical Savanna ◽  
Sedimentary Process ◽  
Climatic Fluctuations ◽  
Climate Conditions ◽  
Depositional Processes ◽  
Lake Formation

As an ecotone, the region between the Amazon Rainforest and Tropical Savanna (Cerrado) biomes is, by definition, more susceptible to climate change. Therefore, understanding palaeoenvironmental dynamics is essential to address the future responses of such transition areas to climatic fluctuations. In this context, we present a new sediment record for the Late-Holocene retrieved from Barro-Preto, currently an oxbow lake located in an ecotone at the southern Brazilian Amazon border. Our multi-proxy data include carbon and nitrogen isotopes, as well as bulk TOC, chlorophyll derivatives, grain-size and microcharcoal analyses, all anchored on a radiocarbon-dated chronology. The sedimentary process recorded at the Barro-Preto Lake responded to both local and regional climate dynamics. It was influenced by river excursions associated to local responses to precipitation changes by the activation of the palaeochannel connecting the main-stem river and the Barro-Preto lake. This activation was evidenced by the presence of different colour lithology laminations accompanied by coarser sediments and also by climate conditions known to influence the Amazon region. Depositional processes linked to lake dynamics and different oxbow lake cycle stages were also important to explain the changes verified in the Barro-Preto record, endorsing the use of this lake formation for palaeoclimatic reconstructions. The record indicated a rising humidity trend, reflected by a progressive increase in lacustrine productivity, in accordance to other studies carried out in the Amazon region concerning the Late-Holocene, associated with a more southward displacement of the Intertropical Convergence Zone. Despite this rising humidity trend, dry episodic events during the Late-Holocene were evidenced by charcoal data, also coherent with regional Amazon studies, albeit exhibiting increased intensity, suggesting that the transitional nature of the environment might have influenced susceptibility to fires.

scholarly journals Scots pine (Pinus sylvestris) dynamics in the Welsh Marches during the mid to late-Holocene

The Holocene ◽  
2021 ◽  
pp. 095968362199465
Author(s):  
Dael Sassoon ◽  
William J Fletcher ◽  
Alastair Hotchkiss ◽  
Fern Owen ◽  
Liting Feng
Keyword(s):  
Pinus Sylvestris ◽  
Scots Pine ◽  
Late Holocene ◽  
British Isles ◽  
Loss On Ignition ◽  
Peat Core ◽  
New Information ◽  
Pine Trees ◽  
Pollen Records

Around 4000 cal yr BP, Scots pine ( Pinus sylvestris) suffered a widespread demise across the British Isles. This paper presents new information about P. sylvestris populations found in the Welsh Marches (western central Britain), for which the long-term history and origins are poorly known. Two new pollen records were produced from the Lin Can Moss ombrotrophic bog (LM18) and the Breidden Hill pond (BH18). The LM18 peat core is supported by loss-on-ignition, humification analysis and radiocarbon dating. Lead concentrations were used to provide an estimated timeframe for the recent BH18 record. In contrast to many other Holocene pollen records from the British Isles, analysis of LM18 reveals that Scots pine grains were deposited continuously between c. 6900–300 cal yr BP, at frequencies of 0.3–5.4%. It is possible that individual Scots pine trees persisted through the wider demise on thin soils of steep drought-prone crags of hills or the fringes of lowland bogs in the Welsh Marches. At BH18, the record indicates a transition from broadleaved to mixed woodland, including conifer species introduced around AD 1850 including Picea and Pinus. The insights from BH18 suggest that the current populations may largely be the result of planting. Comparison of the LM18 findings with other regional pollen records highlights consistent patterns, including a Mid-Holocene maximum (ca. 7000 cal yr BP), long-term persistence at low pollen percentages and a Late-Holocene minimum (ca. 3000 cal yr BP). These distinctive trends encourage further studies on refugial areas for Scots pine in this region and elsewhere.

Geostatistical screening of flood events in the groundwater levels of the diverted inner delta of the Danube River: implications for river bed clogging

2018 ◽  
Vol 10 (1) ◽  
pp. 64-78 ◽  
Author(s):  
Balázs Trásy ◽  
Tamás Garamhegyi ◽  
Péter Laczkó-Dobos ◽  
József Kovács ◽  
István Gábor Hatvani
Keyword(s):  
Spatial Autocorrelation ◽  
Groundwater Monitoring ◽  
Shallow Groundwater ◽  
Monitoring Network ◽  
Danube River ◽  
Monitoring Networks ◽  
Flood Events ◽  
Raw Data ◽  
Monitoring Wells ◽  
Autocorrelation Structure

Abstract The efficient operation of shallow groundwater (SGW) monitoring networks is crucial to water supply, in-land water protection, agriculture and nature conservation. In the present study, the spatial representativity of such a monitoring network in an area that has been thoroughly impacted by anthropogenic activity (river diversion/damming) is assessed, namely the Szigetköz adjacent to the River Danube. The main aims were to assess the spatial representativity of the SGW monitoring network in different discharge scenarios, and investigate the directional characteristics of this representativity, i.e. establish whether geostatistical anisotropy is present, and investigate how this changes with flooding. After the subtraction of a spatial trend from the time series of 85 shallow groundwater monitoring wells tracking flood events from 2006, 2009 and 2013, variography was conducted on the residuals, and the degree of anisotropy was assessed to explore the spatial autocorrelation structure of the network. Since the raw data proved to be insufficient, an interpolated grid was derived, and the final results were scaled to be representative of the original raw data. It was found that during floods the main direction of the spatial variance of the shallow groundwater monitoring wells alters, from perpendicular to the river to parallel with it for over a period of about two week. However, witht the passing of the flood, this returns to its original orientation in ~2 months. It is likely that this process is related first to the fast removal of clogged riverbed strata by the flood, then to their slower replacement. In addition, the study highlights the importance of assessing the direction of the spatial autocorrelation structure of shallow groundwater monitoring networks, especially if the aim is to derive interpolated maps for the further investigation or modeling of flow.

scholarly journals Geological and geomorphological conditions of Archar-Orsoya lowland as a factor for the formation of groundwater chemical composition and in risk of its contamination

2021 ◽  
Vol 35 (1) ◽  
pp. 63-70
Author(s):  
Sava Kolev ◽  
Mila Trayanova
Keyword(s):  
Chemical Composition ◽  
Sand Dunes ◽  
Shallow Groundwater ◽  
Groundwater Table ◽  
Danube River ◽  
Shallow Water Table ◽  
The Danube River ◽  
Sandy Layer ◽  
Shallow Groundwater Table ◽  
Landslide Slope

The Archar-Orsoya lowland is situated in the Danube floodplain west of the town of Lom, NW Bulgaria. It is aligned in a west-east direction along the Danube River and to the south it is bounded by a high landslide slope, built of Pliocene clays and sands. Parallel to the shore, sand dunes are formed with lowered sections between them, in which there are conditions for swamping. The lowland is made up of the alluvial sediments of the Danube, represented by a lower gravelly-sandy layer and an upper sandy-clayey layer. In the gravelly-sandy layer unconfined groundwater is accumulated, with shallow water table – from 0.5 to 7 m beneath the surface. Groundwater is recharged by infiltration of precipitation, surface water and groundwater, which laterally flows into the alluvium from adjacent aquifers. At high waters, the Danube River suppresses the formed groundwater flow and temporarily feeds it. Due to the described formation conditions in the lowland, the chemical composition of groundwater is formed under the influence of intense dynamics and has a low TDS (total dissolved solids). The shallow groundwater table and the corresponding thin unsaturated zone are a prerequisite for easy groundwater contamination with components entering from the surface. Therefore, a map of depth to groundwater table is drawn to identify the most vulnerable areas.

scholarly journals INTERNATIONAL ECOREGIONAL COOPERATION OF UKRAINE FOR THE PROTECTION AND PRESERVATION OF BIODIVERSITY

2019 ◽  
pp. 64-71
Author(s):  
L. Bilous
Keyword(s):  
International Cooperation ◽  
Regional Cooperation ◽  
Mixed Forest ◽  
Danube River ◽  
Forest Steppe ◽  
Beech Forests ◽  
Nature Protection ◽  
Montane Forests ◽  
Mixed Forests ◽  
Data Infrastructure

The place of Ukraine in the systems of the biogeographic and ecoregion order of the world and the biogeographic organization of Europe are considered. The ecoregions are defined as objects of cross-border and international cooperation for protection and conservation of biodiversity and planning of global, regional and national natural protection systems. The review of ecoregions of Ukraine was proposed. 12 ecoregions were defined as existing on the territory of Ukraine. The terrestrial ecoregions are represented by European mixed forests, the Eastern European forest steppe, Pontic steppe, Crimean Submediterranean forest complex, Carpathian montane forests, Pannonian mixed forests. The freshwater ecoregions are represented by Central & Western Europe, Dniester – Lower Danube, Dnieper – South Bug, Crimea Peninsula, Don. The marine ecoregion plays an important role of the nature protection system of Ukraine. This ecoregion is the Mediterranean Sea Ecoregion. The Black and Azov seas belong to its composition. WWF has identified a list of Global 200 that contains 238 ecoregions (142 terrestrial, 53 freshwaters, 43 marine) priority for the protection of their habitat diversity and biodiversity. More than half of these ecoregions are marked as endangered. The habitats of two ecoregions from the Global 200 list are in Ukraine. These are the habitats of the terrestrial ecoregion European-Mediterranean Montane Forests (the mountainous territories of the Crimean and Carpathian regions) and the freshwater ecoregion Danube River Delta. The ecoregions of priority nature conservation in Ukraine are characterized. The features of international cooperation on the biodiversity conservation in these regions are analyzed. The Crimean sub-Mediterranean forest complex is designated as problematic ecoregion for international cooperation. The active participation of Ukraine in the international cooperation for the biodiversity protection in the Euro-Mediterranean mixed forest is outlined. The result of this collaboration is the transnational object «Ancient and Primeval Beech Forests of the Carpathians and Other Regions in Europe». The unique Crimean beech forests with oriental beech (Fagus orientalis), forest beech (Fagus sylvatica), and taurida beech (Fagus taurica) did not enter this object. International cooperation is not possible in annexed territories. Ukraine’s priority has identified the need to develop National Geospatial Data Infrastructure (NGDI). The NGDI is a prerequisite for fruitful international and eco-regional cooperation

scholarly journals Égerlápok a Tengelici-homokvidéken (Carici elongatae-Alnetum glutinosae W. Koch 1926)

2016 ◽  
pp. 13-30
Author(s):  
Balázs Kevey ◽  
István Zsolt Tóth
Keyword(s):  
Betula Pendula ◽  
Forest Canopy ◽  
Sand Dunes ◽  
Alnus Glutinosa ◽  
Danube River ◽  
Sand Ridge ◽  
Herbaceous Species ◽  
Veratrum Album ◽  
Windblown Sand ◽  
Thelypteris Palustris

The study containsa phytosociological analysis of alder swamps found in the Tengelic sand Ridge, an expanse of mostly windblown sand in the westernmost part of the Great hungarian Plain, west of the Danube River. These swamps oc-cur in the depressions among sand dunes, where the ground is covered with water for most part of the year. The species composition is characterized by the dominance of alder (Alnus glutinosa) in the forest canopy with the sporadic occurrence of common birch (Betula pendula). The stands also host several rare herbaceous species, some of which are considered relics in the Great Plain, such as Carex paniculata, C. pseudocyperus, Cirsium palustre, Dryopteris carthusiana, D. dilatata, D. expansa, Listera ovata, Thelypteris palustris, Urtica kioviensis, and Veratrum album.

scholarly journals Bacterioplankton from Two Hungarian Danube River Wetlands (Beda-Karapancsa, Danube-Drava National Park) and its Relations to Environmental Variables

2016 ◽  
Vol 18 (1) ◽  
pp. 1-12
Author(s):  
Hristina Kalcheva ◽  
Mária Dinka ◽  
Edit Ágoston-Szabó ◽  
Árpád Berczik ◽  
Roumen Kalchev ◽  
...  
Keyword(s):  
Environmental Variables ◽  
National Park ◽  
Suspended Solids ◽  
Bacterial Abundance ◽  
The Other ◽  
Danube River ◽  
Oxbow Lake ◽  
Hydrological Connectivity ◽  
Chl A ◽  
Lake Type

AbstractSeasonal and spatial distribution of bacterioplankton from two Hungarian oxbow lake type wetlands, Mocskos-Danube and Riha, was studied. They were both covered by macrophytes and they had different hydrological connectivity to the Danube. The six sampling campaigns from April to October 2014 included parallel samples from the Danube River at Mohács, Hungary. Bacterial abundance was the highest in spring and in Mocskos-Danube, followed by Mohács and Riha. Positive relationships existed between bacterioplankton and temperature on one hand and suspended solids, pH, PO4-P and chl-a on the other. Negative correlations were with DOC, dissolved oxygen and NH4-N.

Redox conditions and groundwater quality issues of selected alluvial aquifers in Serbia

2016 ◽  
Vol 16 (4) ◽  
pp. 1086-1093 ◽  
Author(s):  
B. Majkić-Dursun ◽  
J. Tončić ◽  
A. Petković ◽  
J. Čolić
Keyword(s):  
Groundwater Quality ◽  
Anthropogenic Impacts ◽  
Specific Conductivity ◽  
Shallow Groundwater ◽  
Redox Conditions ◽  
Danube River ◽  
Redox Processes ◽  
Groundwater Abstraction ◽  
Redox Species ◽  
Alluvial Aquifers

Redox conditions are an important regulator of aqueous biogeochemistry and knowledge about them is crucial for an understanding of the fate and occurrence of nitrates, emerging substances, and organic compounds in shallow groundwater. The aim of this paper is to determine redox categories, along with prevailing redox processes, and the differences in groundwater quality between shallow alluvial aquifers of Serbia's major rivers. The research was conducted on public water-supply wells in the alluvial plain of the Velika Morava River, the Danube River, the Tisa River and the alluvial aquifer of the Sava River. The study period is 2010–2014 and the number of collected and analysed samples 243. The redox categories and processes are characterised by concentrations of aqueous redox species (dissolved oxygen, nitrate, dissolved iron, manganese, and sulphate and sulphide concentrations). Parameters such as Eh, total organic carbon, HCO3−, pH, total iron concentrations, temperature and specific conductivity were also analysed. Different geological and hydrogeological settings, groundwater abstraction, distances between the wells and the river, well depths, and anthropogenic impacts result in diverse redox conditions. Groundwater in selected alluvial aquifers is mostly defined as anoxic, with one predominant process, or mixed anoxic, with various redox processes occurring simultaneously.

Constraints on the age of the Great Sand Dunes, Colorado, from subsurface stratigraphy and OSL dates

2013 ◽  
Vol 80 (3) ◽  
pp. 435-446 ◽  
Author(s):  
Richard F. Madole ◽  
Shannon A. Mahan ◽  
Joe H. Romig ◽  
Jeremy C. Havens
Keyword(s):  
Late Holocene ◽  
Sand Dunes ◽  
Middle Pleistocene ◽  
New Information ◽  
Slope Deposits ◽  
Sangre De Cristo

The age of the Great Sand Dunes has been debated for nearly 150 yr. Seven ages ranging from Miocene to late Holocene have been proposed for them. This paper presents new information–chiefly subsurface stratigraphic data, OSL dates, and geomorphic evidence–that indicates that the Great Sand Dunes began to form in the latter part of the middle Pleistocene. The dunes overlie a thick wedge of piedmont-slope deposits, which in turn overlies sediment of Lake Alamosa, a paleolake that began to drain about 440 ka. The wedge of piedmont-slope deposits extends westward for at least 23 km and is as much as 60 m thick at a distance of 10 km from the Sangre de Cristo Range. Ostracodes from one well indicate that the eastern shoreline of Lake Alamosa extended to within 4.3 km of where the Great Sand Dunes eventually formed. The time represented by the wedge of piedmont-slope deposits is not known exactly, but the wedge post-dates 440 ka and was in place prior to 130 ka because by then the dunes overlying it were sufficiently close and tall enough to obstruct streams draining from the Sangre de Cristo Range.

A 12,000-Year Pollen Record from Lake Maliq, Albania

2000 ◽  
Vol 54 (3) ◽  
pp. 423-432 ◽  
Author(s):  
Michelle Denèfle ◽  
Anne-Marie Lézine ◽  
Eric Fouache ◽  
Jean-Jacques Dufaure
Keyword(s):  
Mixed Forest ◽  
Late Glacial ◽  
Pollen Record ◽  
Pollen Data ◽  
The Balkans ◽  
Forest Flora ◽  
New Information ◽  
Winter Temperatures ◽  
History Of ◽  
Glacial Time

Pollen data from Lake Maliq, the first from Albania, contribute new information to the discussion of the vegetational, hydrological, and climatological history of the Balkans since 12,000 yr B.P. During late-glacial time, a perennial lake expanded at Maliq. It was surrounded by a complex vegetation association composed of steppe and mixed forest elements. The highly diverse forest flora suggest that late-glacial forest refugia were more developed here at middle altitude, rather than at higher altitude as previously suggested. The forest developed after 9800 yr B.P., while the water level remained high in the Korçë basin until 5000 yr B.P. Different environmental conditions, characterized by lower available moisture and warmer winters, progressively took place after this date. Human activity in the Korçë basin ca. 4500 yr B.P. was coeval with conditions characterized by an increase in winter temperatures and a decrease in summer moisture.

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