Limitation of lignin derivatives as biomarkers of land derived organic matter in the coastal marine sediments

Lignin oxidation products (vanillyl, syringil and cummaryl phenols), and delta C-13 were measured in a variety of land and marine samples collected in Inner Puck Bay - dominated by marine vascular plants, small river run-off, and shallow bottom, and in Gdansk Bay - characterized by large river run-off, small marine vascular plants population, and the average depth exceeding euphotic zone. Both study areas are parts of the Gdansk Basin, Southern Baltic. Typical delta C-13 values (delta C-13 = -28 parts per thousand) and both composition and concentrations of lignin phenols were measured in samples originating from land. Small, yet easily measurable amounts of lignin phenols were found in marine vascular plants biomass (Sigma 8 =90 mu g/100 mg organic matter). The biomass was characterized by exceptionally high delta C-13 values (-12 parts per thousand). No lignin phenols and typical delta(13)Cvalues (-22 parts per thousand) were measured in marine phytoplankton biomass. delta C-13 and both composition and content of lignin phenols in organic matter of surface sediments collected in the study area fall in the range marked by the end members. The proportion of land derived organic matter calculated using lignin phenols, or delta C-13 in Gdansk Bay were comparable, while in Puck Bay they differed substantially. It was concluded that a) in areas with substantial bottom coverage with vascular plants the two end members approach, usually employed to establish the contribution of organic matter sources, is insufficient, b) organic matter originating from three sources: riverine, phytoplankton, and vascular plants contribute to sedimentary organic matter in Puck Bay with the respective proportion 30:40:30. (C) 2020 Institute of Oceanology of the Polish Academy of Sciences. Production and hosting by Elsevier B.V.