Dataset: Thorium-234 data from SalpPOOP cruise on the R/V Tangaroa to the Chatham Rise (subtropical and subantarctic waters) in October and November 2018

This dataset represents water column Thorium-234 data from the SalpPOOP, Tangaroa Cruise 1810 (aka SalpPOOP cruise). Salinity and density were measured using a CTD.  4-liter (L) samples for total water-column 234Th activity were collected using CTD bottles at approximately 12 depths from the surface to approximately 300 meters.  Samples were acidified with nitric acid to a pH < 2, and a Th-230 tracer spike was added.  Samples were shaken and allowed to equilibrate for 4 to 9 hours.  Samples were then re-basified with ammonium hydroxide to a pH of 8-9, shaken, and allowed to equilibrate for more than 8 hours.  Samples were then vacuum filtered at high vacuum pressure through a quartz (QMA) filter.  Filters were mounted in RISO planchets and counted on a RISO low-level beta multi-counter at Palmer Station, Antarctica.  Following a background count > 6 months later, samples were dissolved in 8M nitric acid / 10% hydrogen peroxide solution and a Th-229 tracer spike was added.  Samples were then analyzed on an ICP-MS to quantify the Th-229:Th-230 ratio, which was used to calculate the initial precipitation and filtration yield of Th-234.  Protocols from Pike et al. (2005) were followed. 

For additional sampling details see Decima et al. (in review, Nat. Comm.).