Boreal lakes are considered hot spots of dissolved organic matter (DOM) processing within the globalcarbon cycle. This study has used FT-ICR mass spectrometry and comprehensive data evaluation to assessthe molecular differences of SPE-DOM between lake column water SPE-DOM and sedimentary porewater SPE-DOM in 10 Swedish boreal lakes of the Malingsbo area, which were selected for their largediversity of physicochemical and morphological characteristics. While lake column water is well mixedand fairly oxygenated, sedimentary pore water is subject to depletion of oxygen and to confinement ofmolecules. Robust trends were deduced from molecular compositions present in all compartments andin all 10 lakes (“common compositions”) with recognition of relative abundance. Sedimentary pore waterSPE-DOM featured higher proportions of heteroatoms N and S, higher average H/C ratios in presence ofhigher DBE/C ratios, and higher average oxygenation than lake column water SPE-DOM. These trendswere observed in all lakes except Ljustj€arn, which is a ground water fed kettle lake with an unique lakebiogeochemistry. Analogous trends were also observed in case of single or a few lakes and operated alsofor compounds present solely in either lake column water or sedimentary pore water. Unique compoundsdetected in either compartments and/or in a few lakes showed higher molecular diversity thanthe “common compositions”. Processing of DOM molecules in sediments included selective preservationfor polyphenolic compounds and microbial resynthesis of selected molecules of considerable diversity.