DOC and TOC of seawater collected during CCGS John P. Tully cruises in the northeast Pacific Ocean from Vancouver Island to Station P from 2018 to 2020 (NCEI Accession 0278690)

This dataset contains chemical data collected on CCGS John P. Tully during cruise Line-P_cruises in the North Pacific Ocean from 2018-09-13 to 2020-02-17. These data include depth, dissolved organic Carbon, and total organic Carbon. The instruments used to collect these data include Niskin bottle and Shimadzu TOC-L Analyzer. These data were collected by Sophia Johannessen of Fisheries and Oceans Canada, Pacific Region, Andrea J. Fassbender of National Oceanic and Atmospheric Administration, and Phoebe J. Lam of University of California-Santa Cruz as part of the "Constraining Upper-Ocean Carbon Export with Biogeochemical Profiling Floats (EXPORTS BGC Floats)" project. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) submitted these data to NCEI on 2021-12-20.

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

Acquisition Description:
Samples
Sampling was conducted aboard the CCGS John P. Tully during five cruises (2018-2020) in the northeast Pacific Ocean from Vancouver Island to Station P (50°N, 145°W).
Fisheries and Oceans Canada (DFO) Cruise numbers: 2018-40, 2019-001, 2019-006, 2019-008, 2020-001

Seawater samples for dissolved and total organic carbon (DOC, TOC) were collected from 10 L Niskin bottles into pre-cleaned 40 mL scintillation vials, with 0.125 cm Teflon low-bleed septa. The vials had been cleaned in Extran 300 and rinsed several times with Type I Ultrapure water. Vials were then soaked in 10% HCl for a minimum of four hours and rinsed several times with Type I Ultrapure water. Cleaned vials were allowed to dry and were then baked at 450°C for a minimum of 5 hours. Septa were briefly washed in 10% HCl, rinsed with Type I Ultrapure water and allowed to air dry.

Samples for TOC were collected directly from the spigot of the Niskin bottle. Samples for DOC were filtered through a Millipore Opticap XL Durapore 0.22 µm inline filter cartridge (Product No. KVGLA04HH3) attached to the spigot. Vials were rinsed three times with sample water and then filled to about three-quarter capacity, to avoid breakage during freezing. The samples were quick-frozen immediately after collection, using a stainless-steel freezer block, and then stored frozen at -20°C until analysis.

DOC and TOC were measured at the Institute of Ocean Sciences, using a Shimadzu TOC-L DOC/TOC analyzer (measurement reproducibility of ± 1.5 %), following Standard Operating Procedure 7 from Chapter 4 in Dickson et al. (2007), with the following modifications: 1) sulphuric acid was used in place of phosphoric acid to reduce vitrification of the column with saline samples; and 2) the sparging time was increased to 150 seconds.

Standards

A 1000ppm standard of potassium hydrogen phthalate was prepared using Type 1 water (defined below). The standard stock solution was stored refrigerated for up to 2 months. Standard dilutions were done by calibrated pipette into volumetric flasks. They were made with Type 1 water that had been further processed to reduce TOC into the 2-3 ppb range. Dilution standards have a shelf life of two weeks. The very low standard concentrations (0.1-0.5 ppm) were made in larger volume flasks to reduce the errors associated with pipetting small amounts. Type I - Ultrapure, Type I water is defined by the American Society for Testing and Materials (ASTM) as having a resistivity of >18 MΩ-cm, a conductivity of <0.056 µS/cm and <50 ppb of Total Organic Carbons (TOC). Low Carbon Water (LCW) is a purchased, 2 μM, reference standard used to determine the instrument blank. Miami Seawater is a purchased, 42-45 μM, reference standard used to determine when the column/instrument was running cleanly enough to measure low concentrations in seawater.