Controls on riverine δ30Si signatures in a temperate watershed under high anthropogenic pressure (Scheldt - Belgium)

► First seasonal variation of riverine δ30Si in a highly anthropogenised watershed ► Mean annual δ30Si signature output from the Scheldt tidal river is estimated at 0.95‰. ► δ30Si in tidal river result from mixing with tributaries except when diatoms bloom. ► Si isotopic signatures of tributaries are highly correlated with land use. ► River Si isotopic signatures are more sensitive to processes than Si concentrations.