Thorium isotopes in the water column at station PS70/260@en

Dissolved samples were filtered directly from the 24 L CTD-Niskin® bottles into cubitainers (LDPE) using 0.45 µm pore size Acropaks®. Samples were collected in volumes of 1 L, 2 L, and 10 L and acidified with concentrated ultraclean HNO3. Seawater for the analysis of total 230Th was sampled without filtration. The analyses were done at the University of Minnesota, Minneapolis, following methods described by Shen et al., 2003. The concentrations were measured using Inductively Coupled Plasma Mass Spectrometry (ICP-MS, Thermo Finnigan, Neptune) equipped with an secondary electron multiplier (SEM) and a Retarding Potential Quadrupole (RPQ) energy filter. […]