This dataset contains the bulk sediment parameters (total organic carbon (TOC), carbon nitrogen ratio (C/N), δ13C), lipid biomarker (branched glycerol dialkyl glycerol tetraethers (brGDGTs), crenarchaeol, long-chain diols, long-chain n-alkanes, alkenones, sterols) and palynological (dinoflagellate cysts, pollen) content of 20 surface sediments (0-2 cm) from the northern Gulf of Mexico, near the Mississippi and Atchafalaya river mouths. Samples were retrieved from three land-sea transects; (1) offshore the Mississippi river, (2) offshore the Atchafalaya river and (3) on the 20 m isobar on the Louisiana shelf, during a research cruise in February 2020. Samples were analysed on their organic carbon composition, which was divided into soil-, fluvial- and plant-derived terrestrial organic carbon, and marine produced organic carbon, to investigate if the composition and quality of the terrestrial carbon had an influence on their dispersal patterns.