Particulate Th data from samples collected on 5 cruises at Station ALOHA off Hawaii and Station M off California from 2019 to 2020 (NCEI Accession 0294376)

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:

Particulate Th

Dataset Description:
Methods and Sampling:
Particulate sample collection methods are similar to those described by Roca-Marti et al. (2021). Briefly, 142 mm diameter, 0.3 micron (µm) pore-size GF75 filters, 1 µm pore-size QMA filters, and 53 µm pore-size Nitex filters were cleaned according to trace metal clean protocols. Filters were mounted sequentially by size on metal-free mini-MLVFS filter holders attached to the in situ pumps and deployed at depths between 10 and 4000 depending on the cruise. Between ~500-2000 L of water were filtered per deployment at a rate of 8 L/minute. High flow rates of ~20 L/minute were used to filter large volumes of water (~5000-7000 L) required for capturing sufficient > 53 µm particles for isotopic and compound specific analyses.

Small particles collected using QMA and GF75 filters were subsampled using a ~22 mm Delrin punch for particulate 234Th, total carbon (C), and bulk C and nitrogen (N) isotopic analyses under trace metal clean conditions. Large particle (> 53 µm) samples for 234Th, C, and bulk N were rinsed onto 25 mm QMA filters using 0.2 µm filtered seawater and visible swimmers were removed. Samples were then dried, mounted onto RISO discs, and stored at 4˚C prior to and immediately following counting. All samples were counted on a low level RISO beta counter using a helium/1%butane gas mixture.