Since 2017, we investigated iDOM in tropical and temperate rivers across Amazonia and Scotland using the next-generation liquid chromatography organic carbon detection – organic nitrogen detection system utilised by Pereira et al. (2014). Monthly sampling of rivers including the Cree, the Clyde and the Forth show evidence for iDOM mobilisation, but no clear quantitative relationship between DOC and iDOM. Humic compounds are the dominant DOC fraction (40 to 80%), contrasting with observations from tropical rivers. In order to get a better understanding of short-term temporal changes of iDOM and its mobilisation in headwaters we studied the DOM composition and changes in a small headwater stream of the River Forth in Scotland, the Menstrie Burn.