Dataset: Particulate Thorium-234 Flux
Deployment: KM1910

Particle flux measurements from the Chief Scientist Training cruise generally followed the methods of the Hawaii Ocean Time-Series (HOT). Measurements were made at 75 meters, 150 meters, and 300 meters using multiple cylindrical particle interceptor traps deployed on a free-floating array for approximately 3 days twice during cruise KM1910 at station ALOHA. Sediment trap design and collection methods are described in Winn et al. (1991). Sediment trap tubes were split, with roughly 50% of the split going to Th-234 particulate analysis.

All thorium-234 data were decay corrected back to mid-deployment times. The subsampled trap material was gradually poured into 25 millimeter (mm) filter funnels containing 25 mm QMA or GFF filters (most were QMA and efficiency differences were taken into account). Once all the trap subsample liquid was filtered, the 25 mm filter was dried at low temperature for a few hours (<60 degrees Celsius). Samples were mounted and prepared for beta counting according to the techniques noted in Pike et al., 2005 and Clevenger et al., 2021.