Freshwater particulate organic radiocarbon for four major UK catchments, 2013-2014

We collected 5 litre water samples from the tidal limit of four major catchments in the UK (Ribble, Hampshire Avon, Conwy, Scottish Dee) in high-density polyethylene bottles. To minimise risk of carbon contamination, all equipment used during sampling and processing was new or acid-washed and all samples were managed in a radiocarbon tracer-free laboratory. For the Ribble, Conwy and Dee sites samples were collected during high-flow events. For the Avon, which has a much less flashy flow regime, they were taken at regular intervals throughout one year. High flow events were identified from daily river levels measured at gauging stations near the sampling sites, and made available on-line by the Environment Agency of England and Wales and the Scottish Environment Protection Agency. During the period October 2013-October 2014, four samples were taken for most of the sites, but only three each at the Gairn and Dee A sites. Additional 500 or 1000 mL samples were collected for the determination of SPMconcentration and the carbon content of the SPM.