Surficial sediment samples were collected from Scottish adjacent waters from a variety of research vessels using different methods of sediment collection (detailed in supplementary documentation). The location of the samples were recorded using GPS alongside the water depth. Upon collection, the samples were described using the modified Folk scheme and stored at -20 Celsius. Additional samples were sourced from the British Geological Survey (BGS) sample repository (Keyworth, UK) which were collected by experienced marine geologists for BGS and the United Kingdom Hydrographic Organisation (UKHO) following the same sampling procedure detailed above.
Prior to analysis the samples were freeze dried and milled to a fine powder. Organic and Inorganic carbon content of the samples were measured using the temperature gradient method of elemental analysis (detailed in the supporting documentation). All laboratory equipment were calibrated in accordance with the laboratory practises at the University of St Andrews. Results were recorded on to lab sheets and transferred into an Excel file. Results were exported as comma separated value (.csv) file for ingestion into the data repository.