²²⁴Ra, ²²⁸Th in sediment and pore water – 30 g sediment

This method specifies the minimum requirements and laboratory methods for measuring ²²⁴Ra and ²²⁸Th in sediment core and pore water samples via MnO₂ co-precipitation–RaDeCC counting.

Sediment cores are collected with polycarbonate columns and sectioned based on the research. Pre-treatment on each sediment slice must be completed as soon as possible on board or at laboratory. The sediment slurry is filtrated using a special filtration unit and the sediment plate is finally measured by RaDeCCs within 12 h after sampling. The second measurement should be done in the same RaDeCCs after 8~10 days. Isotope ingrowth and decay corrections are applied to calculate the ²²⁴Ra and ²²⁸Th activities (see Cai et al., 2012 ).