Dataset: Size Fractionated Particulate Thorium-234 measurements collected during the 2012-2013 Palmer Field Season

Final no updates expectedDOI: 10.26008/1912/bco-dmo.881137.1Version 1 (2022-08-02)Dataset Type:Other Field Results

Principal Investigator, Contact: Michael R. Stukel (Florida State University EOAS)

BCO-DMO Data Manager: Sawyer Newman (Woods Hole Oceanographic Institution)


Project: Quantifying Processes Driving Interannual Variability in the Biological Carbon Pump in the Western Antarctic Peninsula (WAP Carbon export)


Abstract

Particle-bound Th-234 measurements and C:234Th ratios for size-fractionated particles collected during the 2012-2013 field season of the Palmer LTER program near Anvers Island in the Western Antarctic Peninsula. Particle-bound Th-234 is a useful tracer for particle scavenging and sinking processes in the ocean. Particles were sampled from 0, 10, 20, or 30 m depth and filtered through a 50-µm sieve before being concentrated onto a GF/F filter for carbon and Th-234 analyses.

Particulate organic carbon, nitrogen, and 234Th associated with >50-µm particles was measured at depths from the surface to 30 m at Station E near Palmer Station.  Samples were collected using two different methods.  For surface sampling, 20-L carboys were filled with surface seawater and gently poured through a 50-µm sieve.  For samples from depth, water was pumped to the surface using a Monsoon pump and filtered through a 50-µm sieve.  Volumes filtered varied depending on particle load but were typically between 50 and 100 L.  Sieves were rinsed onto pre-combusted glass fiber (GF/F) filters.  Filters were dried and mounted in RISO planchets.  Samples were then counted in a RISO low-level beta multi-counter to determine activity of 234Th. Background counts were conducted >6 half-lives after collection.  Samples were then acidified to remove CaCO3 and analyzed in an elemental analyzer to determine particulate organic carbon and particulate nitrogen on filters.  For additional details, see Stukel et al. (2022). 


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Methods

Stukel, M. R., Asher, E., Couto, N., Schofield, O., Strebel, S., Tortell, P., & Ducklow, H. W. (2015). The imbalance of new and export production in the western Antarctic Peninsula, a potentially “leaky” ecosystem. Global Biogeochemical Cycles, 29(9), 1400–1420. Portico. https://doi.org/10.1002/2015gb005211
Methods

Stukel, M. R., Schofield, O. M. E., & Ducklow, H. W. (2022). Seasonal variability in carbon:234thorium ratios of suspended and sinking particles in coastal Antarctic waters: Field data and modeling synthesis. Deep Sea Research Part I: Oceanographic Research Papers, 184, 103764. https://doi.org/10.1016/j.dsr.2022.103764