ISSN 1392-110X
ISSN 2029-056X (online)
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2006 m. Nr. 2
Component-based and radioisotope signature of
lacustrine sediments in Eastern Lithuania
Jonas MAŽEIKA, Arūnas GUDELIS
Results of investigation of sedimentation processes in a few lakes located in the eastern part of Lithuania are presented. The Niemistö gravity corer was used for taking short (up to 80 cm in length) sediment cores. The sliced and dried samples were examined for 210Pb and 137Cs specific activity and for components of sedimentary matrix. The estimated parameters were mean sediment mass accumulation rate (g/cm2/year), derived linear rate of accumulation of wet bulk sediment layer (cm/year), percentage of components of sedimentary matrix. The radioisotope geochronology of sediments was outlined based on constant 210Pb flux and constant sedimentation rate model. Basing on radioisotope geochronology, temporal changes of the components of sedimentary matrix in particular lakes related to environmental changes have been studied. The dry mass accumulation rate for particular cores from different lakes was the following: Lake Drūkšiai 0.06 g/cm2/year, Lake Mažasis Beržinis 0.024 g/cm2/year, Lake Šventas 0.017 g/cm2/year, Lake Duobulis 0.012 g/cm2/year. The linear sedimentation rates of wet sediments for cores from different lakes were derived: Lake Drūkšiai 0.3–0.9 cm/year, Lake Mažasis Beržinis 0.1–0.6 cm/year, Lake Šventas – 0.3-1.0 cm/year, Lake Duobulis 0.1–0.4 cm/year. Based on radioisotope geochronology, the time intervals of change of sediment sources related with the major hydrological events and hydrographic changes in the relevant catchments were determined.
Keywords: lakes, sedimentation rate, lead-210, caesium-137, radioisotope geochronology
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