Authors: JaanMati Punning Galina Kapanen Tiit Hang Natalia Davydova Mihkel Kangur
Publish Date: 2008/02/03
Volume: 599, Issue: 1, Pages: 97-104
Abstract
A comprehensive study chronological lithological and geochemical of an 85 m postglacial sediment sequence from Lake Peipsi was conducted to elucidate the effects of lakelevel changes on the sedimentary environment and biogeochemical dynamics in a large lake Four lithological units were distinguished in the sediment sequence studied clayey silt slightly laminated greyish carbonaceous gyttja brownishgrey gyttja and dark gyttja These units indicate that large shifts in sedimentation processes occurred in the past The sediment data show that fluctuations in water depth had a profound impact on the lake environment recorded as changes in the lithological composition phosphorus content of sediments and composition of diatom assemblages The corresponding changes are best reflected in sediments accumulated during phases of regression when the lake area was also smaller As the water depth and area of the lake increased waveinduced erosion and resedimentation smoothed or even disturbed the initial information The increase of phosphorus content in the unconsolidated highporosity surface sediments 05 m is most probably connected with active diffusion and matter exchange between the watersediment poolsThe study was supported by the Estonian target financed project SF0280016s07 and the Estonian Science Foundation grant no 5370 This research was partly supported by the Estonian Environmental Investment Centre contract no 06063/381 We thank our colleagues Jaanus Terasmaa for assistance in the fieldwork and Liisa Puusepp and Anna Ludikova for the help in compiling the diatom diagram We thank the Estonian Border Guard for supporting field work in Lake Peipsi and Mrs Tiia Kaare for improving the language The journal reviewers and the guest editor of the special issue are acknowledged for constructive comments
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