The branched vs. isoprenoid tetraethers (BIT) index, which is based on the relative abundance of non-isoprenoidal, so-called branched glycerol dialkyl glycerol tetraethers (brGDGTs) versus a structurally related isoprenoid GDGT "crenarchaeol", has been used to trace soil organic carbon (OC) from the continent to the ocean. However, it has been found in some locations that the BIT index can be primarily influenced by crenarchaeol concentrations and brGDGT production in fresh water rather than by soil-derived brGDGT concentrations. This may hamper the application of this proxy as an indicator for the input of soil OC. Here we examined the concentration and distribution of brGDGTs as well as variations in the BIT index in marine surface sediments from five transects (Douro, Mondego, Estremadura, Tagus, and Sado) along the southern Portuguese continental margin and in marine suspended particulate matter (SPM) from the Douro and Tagus transects. Higher BIT values and brGDGT concentrations (normalized to OC ... : Supplement to: Zell, Claudia; Kim, Jung-Hyun; Dorhout, Denise J C; Baas, Marianne; Sinninghe Damsté, Jaap S (2015): Sources and distributions of branched tetraether lipids and crenarchaeol along the Portuguese continental margin: Implications for the BIT index. Continental Shelf Research, 96, 34-44 ...