We collected a set of continuous gravity and piston cores with varved sediments from four lakes that probably cover the entire Holocene (i.e. the last 11,600 years) or even include the Late-Glacial (i.e. the last ca. 14,000 years). Our research strategy will be as follows:

1. The use of non-destructive and high-resolution XRF scanning techniques enable us to carry out a precise and fast preliminary evaluation of the recovered sediment cores.

2. Varve chronologies will be elaborated by microstratigraphic thin section analyses. Continuous record of varve thickness variations will be cross-checked by radiocarbon dating. Additionally, ²¹⁰Pb dating will be carried out to link records to the present.

3. We want to use the capabilities of the ITRAX XRF core scanner to produce continuous high-resolution (200 µm) XRF scans that show short-term fluctuations in elemental composition.

4. Analyses of discrete samples will be performed with 10 cm resolution and with 1 cm resolution within the time-windows of special interest. A wide range of proxies will be employed:

   • Basic geochemical indicators (TIC, TOC, BSi) and isotopic data will provide a measure of primary productivity. We will use the C/N ratio and stable isotope composition of organic matter to decipher the origin of organic matter. δ¹³C_carb values will provide insight into temporal variations of lacustrine primary productivity and human induced eutrophication as this proxy is directly linked to the dissolved inorganic carbon pool.

   • Oxygen stable isotope data of endogenic carbonates and calcareous microfossils will provide information about hydrological and water temperature changes. The comparison between the δ¹⁸O_carb patterns of the four records distributed along a transect from W to E in northern Poland will allow separating regional hydrological variations due to climatic changes from local watershed disturbances.

   • The biological studies related to pollen and diatoms will shed light on questions related to lake internal productivity and changes of limnological conditions in general, reconstruction of vegetation cover and land use patterns and climatic variability as one of the main forcing factors.

5. All these data and interpretations will be supported by the study of modern processes in the lakes and their catchment areas which helps to understand the mechanisms that work together and form the sedimentary record.

Altogether, four well-dated records with a large variety of proxy parameters will become available along this ca. 700 km long W-E transect through northern Poland. Thus spatiotemporal climate and environmental changes can be investigated in detail.