Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

This dataset includes water column concentrations of DOC, TDN, and nutrients collected from February 13, 2013 to March 18, 2013 along the Ross Sea shelf. Sampling focus was in the western Ross Sea along with a zonal section on 76° 30ˈS.

Related files and references:
Physical data from NBP 1302 are archived by the Marine Geoscience Data System. Data held there include shipboard continuous underway (e.g., thermosalinograph and fluorescence), bathymetry, CTD, meteorological, XBT, and navigation. The project link: http://www.marine-geo.org/tools/search/entry.php?id=NBP1302

DOC methodology
Dickson, A.G., Sabine, C.L., Christian, J.R. (Eds.) Guide to best practices for ocean CO₂ measurements. PICES Special Publication 3, 191.

Phosphate methodology
K Grasshoff. 1976. Methods of seawater analysis. Verlga Chemie, Weinheim

Silicate methodology
J.D.H Strickland and T.R. Parsons. 1968. A Practical Handbook of Seawater Analyses. Ottawa: Fisheries Research Board of Canada, Bulletin.

Nitrate methodology
Braman, R.S. and S.A. Hendrix. 1989. Nanogram nitrite and nitrate determination in biological materials by vanadium(III) reduction with chemiluminescence detection. Anal. Chem. 61 (24). 2715-2718.

Sampling and Analytical Methodology
DOC: Samples were run through an inline GF/F 0.7 uM filter by gravity filtration directly from the Niskin bottles and stored frozen in polycarbonate bottles until shore-based analyses. DOC concentrations determined by high temperature catalytic oxidation (TOC-VCPN analyzer, Shimadzu) according to Dickson et al. (2007). Hansell Deep Reference Water was used as an external standard.
Standard deviation: 1.5 µM

Phosphate: Samples were stored in HDPE bottles at 4oC until analysis (within one week of sampling). Phosphate was determined colorimetrically according to Grasshoff (1976) using a fiber optic spectrophotometer (Ocean Optics) onboard RV NBP. Potassium phosphate monobasic (KH₂PO₄) was used as a standard.
Standard deviation of reference water: 0.04 µM PO₄

Silicic Acid: Samples were stored in HDPE bottles at 4oC until analysis (within one week of sampling). Silicic acid was determined colorimetrically according to Strickland and Parsons (1968) using a spectrophotometer onboard RV NBP and standardized with sodium fluorosilicate Na₂SiF₆ in artificial seawater (Salinity=28 ppt).
Standard deviation of reference water: 1.44 µM Si/p>

Nitrate (Note: NO₃ refers to NO₂+NO₃): Samples were stored frozen (for up to 6 months) prior to analysis in a shore-based laboratory. Sample NO₃ was reduced to NO using a heated, acidic V (III) solution and determined by chemiluminescent detection of NO. [Braman and Hendrix 1989]. Potassium nitrate (KNO₃) was used as a standard.
Standard deviation for replicate analyses/sample: 0.2 µM NO₃

Data Processing:
Data converted from micromol/L to micromol/kg

Quality flag descriptions:
2: QC was performed; considered good data
7: QC was performed; considered bad / questionable data
5: Value is missing

BCO-DMO Processing Notes
- Generated from original file "TRACERS_DOC_TDN_NUTS_Hansell2.xls" contributed by Sarah Bercovici
- Parameter names edited to conform to BCO-DMO naming convention found at Choosing Parameter Name
- Date formatted to YYYYMMDD

Sinking particles are a major element of the biological pump and they are commonly assigned to two fates: mineralization in the water column and accumulation at the seafloor. However, there is another fate of export hidden within the vertical decline of carbon, the transformation of sinking organic matter to fine suspended and/or dissolved organic fractions. This process has been suggested but has rarely been observed or quantified. As a result, it is presumed that the solubilized fraction is largely mineralized over short time scales. However, global ocean surveys of dissolved organic carbon are demonstrating a significant water column accumulation of organic matter under high productivity environments. This proposal will investigate the transformation of organic particles from sinking to solubilized phases of the export flux in the Ross Sea. The Ross Sea experiences high export particle production, low dissolved organic carbon export with overturning circulation, and the area has a predictable succession of production and export events. In addition, the basin is shallow (< 1000 m) so the products the PIs will target are relatively concentrated. To address the proposed hypothesis, the PIs will use both well-established and novel biochemical and optical measures of export production and its fate. The outcomes of this work will help researchers close the carbon budget in the Ross Sea.