Sedimentation in Lake Pleshcheyevo (Central Part of the East European Plain) in the Late Holocene Under Conditions of Increased Anthropogenic Impact

In the present study, sedimentation conditions and rates in Lake Pleshcheyevo (Yaroslavl region, Central part of the East European Plain) over the past 3600 years were reconstructed based on lithological, geochronological, isotopic, and paleobiological studies of bottom sediments from the deep part of the lake. C/N ratio analysis was used to identify the sources of organic carbon in the lake bottom sediments. Studies of anthropogenic indicators in pollen spectra provided a qualitative comparison of the two age–depth models. Deepwater mesotrophic to eutrophic sedimentation conditions were established during the epoch of cattle farming, 3600–2700 cal yr BP (1600–750 BCE), with relatively high (up to 0.04–0.05 g cm−2 year−1) mass accumulation rates (MAR) corresponding to period of high fluvial activity on the East European Plain. About 1900 cal yr BP (since the beginning of the 1st century CE), with the spread of slash-and-burn agriculture, lake eutrophication occurred, with an increase in sedimentation rates associated with deforestation and ploughing of territories. From 1300 to 200 cal yr BP (7th to the 19th century CE), sedimentation rates decreased. A sharp (up to 0.07 g cm−2 year−1) increase in MAR from the end of the 19th century to the middle of the 20th century was established. Similar trends are typical of lakes within the developed areas and are associated with expansion of cultivated agricultural land.