Radium isotopes and 228Th in surface water samples collected on POLARSTERN expedition PS94

• Main Authors: Rutgers van der Loeff, Michiel M, Stimac, Ingrid, Bauch, Dorothea, Valk, Ole, Geibert, Walter, Vieira, Lucia Helena
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2021
• Subjects: GEOTRACES; In-Situ-Pump; Radium; Thorium; Event label; Station label; DATE/TIME; LATITUDE; LONGITUDE; DEPTH, water; Thorium-228; Thorium-228, standard deviation; Radium-224 excess; Radium-224 excess, standard deviation; Radium-224; Radium-224, standard deviation; Radium-226; Radium-226, standard deviation; Radium-228; Radium-228, standard deviation; Method comment; Thorium-228, particulate; Area/locality; In situ pump; Water pump; RaDeCC; Gamma spectroscopy; PS94; Polarstern; Global marine biogeochemical cycles of trace elements and their isotopes GEOTRACES; Arctic; Makarov Basin; makarov basin
• Online Access: https://dx.doi.org/10.1594/pangaea.936052; https://doi.pangaea.de/10.1594/PANGAEA.936052

Radium isotopes are produced by decay of an isotope of thorium, a highly particle reactive element. Radium is relatively soluble in seawater such that once a thorium isotope in suspended or bottom sediments decays, a fraction of the produced radium isotope may be released to solution. 224Ra (3.7-day half-life) and 223Ra (11.4-day half-life) are used extensively as tracers for interaction on the shelf and for submarine groundwater discharge (SGD). 228Ra is strongly enriched in shelf waters and in the Transpolar Drift (TPD) and its half-life (5.8 years) is well suited to study the fate of this shelf-derived water in the central Arctic. This dataset collected in the framework of GEOTRACES during PS94 in 2015 shows that the input of 228Ra in the TPD has increased since previous studies in 2007 and 2011. The distribution of 228Ra-daughter 228Th (1.9 y half-life) and the 228Th/228Ra ratio are measured to trace particle fluxes. The accumulation of 226Ra (1620 y half-life) in the deep Makarov Basin can be used as a measure of basin ventilation time.