Dataset: Depth profiles of suspended dissolved and particulate 232Th, 230Th, and 231Pa from R/V Knorr KN199-04, KN204-01, subtropical North Atlantic Ocean from 2010-2011 (U.S. GEOTRACES NAT project)

DMO NOTE on GNAZT Suspended Particulate Th/Pa:
- version 4 served on 29 Sept 2015; combined both dissolved and particulate Th & Pa datasets into one.
See dataset "GT10-11 - Dissolved and Particulate Th and Pa"
- version 3: none
- version 2: 8 Aug. 2014
- version 1: 31 Jan. 2013

Notes:

This data refers to the "suspended" size fraction of seawater particles (written with the suffix "_susp"). The particulate samples were collected by in-situ pumping over paired 0.8?m Pall Supor800 polyethersulfone filters behind a 51 ?m Sefar polyester mesh prefilter (See sampling Methodology below for details). Analysis of the paired Supor filters represents a particle size class approximating 0.45-51 µm (Bishop et al. 2012), while the top filter alone represents 0.8-51 µm and it is this size class referred to here as "suspended". We measured a select number of top and bottom filters separately for radionuclides and found that the bottom filters had radionuclide levels that were indistinguishable from clean filter process blanks. Therefore whether or not samples were analyzed as top and bottom paired, or the top filter alone, we refer to the particle size class represented as 0.8-51 µm.

Radionuclide concentrations are given as the mass of radionuclide contained in a given volume of pumped seawater: femtograms (fg = 10-15 g) radionuclide per kilogram (kg) seawater for 230Th and 231Pa, and picograms (pg = 10-12 g) radionuclide per kg seawater for 232Th. Sample size was measured by volume (liters) of seawater pumped by mass flow controllers on the in-situ pumps, but we converted seawater volume to seawater mass using a fixed seawater density of 1.025 kg/L. The units are written simply as fg/kg and pg/kg. Note that the counterpart radionuclide data in the dissolved phase (<0.45 µm) from this CRUISE are also reported in fg and pg per kilogram of seawater. Concentrations below detection are listed as ‘bdl’.