Precise measurement of 226Ra/230Th disequilibria in deep-sea sediments by high-sensitivity ICP-MS

We describe a new method suitable for the precise and accurate determination of 226Ra in porewater sediment samples using single-collector sector field ICP-MS (ThermoFisher Element XR) equipped with an Apex-Q desolvation device high-sensitivity Jet-X interface. In combination 230Th measurements parallel samples, this allows quantification 226Ra/230Th disequilibria surface cores, thereby enabling use isotope pair as tracer solute transfer across sediment-water interface deep ocean. The integrates step dilution 228Ra internal spike, pre-concentration Ra Ba by MnO2 precipitation, efficient separation from other undesirable elements cation exchange resin Triskem Sr-spec resin. With inclusion one or two additional columns up to 16 bed-volumes lower molarity (1.7 M) HCl eluent, our procedure eliminates complicated matrix effects persistently encountered previous studies, provides highly purified solution measurement XR apparatus. Consequently, we are able determine activity ∼20–50 ml 100 mg precision ∼1.0% accuracy ∼99.2%. solid phase core North Pacific Ocean allowed distribution coefficient (Kd) be constrained tightly within range 4700–11,600 g−1. Moreover, aid one-dimensional model, us estimate flux 1140 ± 20 dpm m−2 y−1 core.