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001-es BibID:BIBFORM009591
Első szerző:Korponai János (biológus)
Cím:Transition from shallow lake to a wetland: a multi-proxy case study in Zalavári Pond, Lake Balaton, Hungary / János Korponai, Mihály Braun, Krisztina Buczkó, István Gyulai, László Forró, Judit Nédli, István Papp
ISSN:0018-8158 1573-5117
Megjegyzések:Lake Balaton, the largest shallow lake in Central Europe, has no natural outlet, therefore, underwent water level changes during its 15,000-17,000 years of history. The lake is very sensitive to both climate changes and human impacts. Surroundings have been inhabited since the Stone Age; however, heavy human impact can be recognized during the past 6000 years. In this study, we established three different stages for and reconstructed water level changes of Lake Balaton by geochemical data, subfossil Cladocera and diatom remains in the sediments of the Zalavári Pond, a part of the Kis-Balaton wetland. In 9900-8600 cal. year BP, climate was dry, water level was low, and there was a wetland in this area. Although organic matter content was low in the sediment, the ratio of Fe/Mn was high. Between 5600 and 5000 cal. year BP, water level increased, Fe/Mn ratio shows that oxygen conditions of sediments was improved in agreement with the relatively low number of diatom remains and dense chydorid remains. About 5000 cal. year BP, water level of Lake Balaton decreased as indicated by high organic content with low carbonate and high Fe/Mn ratio in the sediments (oxygen depletion). At the bottom of this section, high Fe and S concentrations showed accumulation of pyrite (FeS2) that is common in wetlands with very low redox potential. Low abundance of Cladocera remains together with rich and diverse diatom flora confirm the low water level hypothesis. Our data support that the water level of Lake Balaton was higher between 8600 and 5000 cal. year BP than it is at present.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Lake Balaton
cladocera remains
trace metals
shallow lake
Megjelenés:Hydrobiologia. - 641 : 1 (2010), p. 225-244. -
További szerzők:Braun Mihály (1966-) (vegyész, analitikus) Buczkó Krisztina (1962-) (biológus) Gyulai István (1980-) (biológus) Forró László (1954- ) (biológus) Nédli Judit (1980- ) (biológus) Papp István (1980-) (vegyész)
Internet cím:DOI
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001-es BibID:BIBFORM009590
Első szerző:Magyari Enikő (biológus)
Cím:Palaeolimnology of the last crater lake in the Eastern Carpathian Mountains: a multiproxy study of Holocene hydrological changes / Enikő Magyari, Krisztina Buczkó, Gusztáv Jakab, Mihály Braun, Zoltán Pál, Dávid Karátson, István Pap
Megjegyzések:A multi-proxy investigation (loss-on-ignition, major and trace elements, pollen, plant macrofossil and siliceous algae) was carried out on the sediment of a crater lake (Lake Saint Ana, 950 ma.s.l.) from the Eastern Carpathian Mountains. Diatom-based transfer functions were applied to estimate the lake's trophic status and pH, while reconstruction of the water-depth changes was based on the plant macrofossil and diatom records. The lowest Holocene water depths were found between 9000 and 7400 calibrated BP years, when the crater was occupied by Sphagnumbog. Significant increases in water depth were found from 5350(1), 3300(2) and 2700 cal yr BP. Of these, the first two coincided with major terrestrial vegetation changes, namely (1) the establishment of Carpinus betulus on the crater slope and (2) the replacement of the lakeshore Picea abies forest by Fagus sylvatica. The chemical record indicated significant soil changes along with the canopy changes (from coniferous to deciduous) that led to increased in-lake productivity and pH. A further increase in water depth around 2700 cal yr BP resulted in stable thermal stratification and hypolimnetic anoxia that via P-release further increased in-lake productivity and eventually led to phytoplankton blooms with large populations of Scenedesmus. High productivity was depressed by anthropogenic lakeshore forest clearances from ca. 1000 cal yr BP that led to the re-establishment of P. abies on the lakeshore and consequent acidification of the lake water. On the whole, these data suggest that Lake Saint Ana is a vulnerable ecosystem: in-lake productivity is higher under deciduous canopy and litter, and considerably repressed by coniferous canopy and litter. The lake today subsists in a managed environment that is far from its natural state. This would be a dense F. sylvatica forest supplying more nutrients and keeping up a more productive in-lake flora and fauna.
Tárgyszavak:Természettudományok Földtudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Hydrobiologia. - 631 (2009), p. 29-63. -
További szerzők:Buczkó Krisztina (1962-) (biológus) Jakab Gusztáv (1975- ) (paleontológus) Braun Mihály (1966-) (vegyész, analitikus) Pál Zoltán Karátson Dávid (1964- ) (földrajz-biológia tanár) Papp István (1980-) (vegyész)
Internet cím:DOI
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