Total Th data from samples collected on 5 cruises at Station ALOHA off Hawaii and Station M off California from 2019 to 2020 (NCEI Accession 0294382)

This dataset contains chemical data collected on R/V Atlantis, R/V Kilo Moana, and R/V Western Flyer during cruises AT42-10, KM1914, KM2002, KM2008, and Pulse 72 in the North Pacific Ocean from 2019-04-01 to 2020-08-31. These data include depth and thorium-234 activity. The instruments used to collect these data include CTD - profiler, Inductively Coupled Plasma Mass Spectrometer, McLane Large Volume Pumping System WTS-LV, and Riso Laboratory Anti-coincidence Beta Counters. These data were collected by Jeffrey C. Drazen of University of Hawaii at Manoa and Claudia R. Benitez-Nelson of University of South Carolina as part of the "Collaborative Research: Assessing the relative importance of small vs large particles as sources of nutrition to abyssal communities (Abyssal food web)" project. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) submitted these data to NCEI on 2024-04-02.

The following is the text of the dataset description provided by BCO-DMO:

Total Th

Dataset Description:
Methods and Sampling:
Total 234-Thorium (Th) sampling and analyses are similar to those described in Buesseler et al. (2020). Briefly, 2 liters (L) of seawater was collected from 5 - 2500 meters (m) depth. Samples were acidified to pH ~1 and a 230Th yield tracer added. After samples were allowed to equilibrate for 6-8 hours, the pH was adjusted to ~8-9, and reagents were added to form a Mn-oxide precipitate that scavenges Th. Samples were allowed to stand for ~8 hours; after which the precipitate was filtered onto a 25-millimeter (mm) quartz microfiber filter (QMA) and dried at 60 degrees Celsius (˚C) before counting on a low level RISO beta counter using a helium/1%butane gas mixture. Samples were recounted after six months to account for any residual background activity stemming from other naturally occurring radionuclides that co-precipitate with the Mn-oxide. 230Th sample recoveries were measured using ICP-MS after acid digestion and spiking with 229Th according to the methods described in Pike et al. (2005) and Umhau et al. (2019) to account for any loss of sample material during processing.