Effects of weathering on organic matter

► Characterization of bulk and molecular changes caused by oxidative weathering of immature terrestrial organic matter. ► Oxidative weathering raises vitrinite reflectance values by ca. 0.1%. ► All biomarkers and biomolecules decreased significantly in concentration or were totally depleted. ► Concentration of most polynuclear aromatic hydrocarbons (PAHs) decreased by 50-80%. ► Concentrations of more reactive and less stable PAHs like benzo[a]pyrene and perylene decreased by >90%.