Table of Contents

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

This dataset includes important measures related to the carbon system in the Ross Sea, Antarctica.

Physical data from the R/V Nathaniel B. Palmer cruise NBP 1302 collected along with this dataset 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

For explanation and units of acronyms such as dC13_POM used below, please refer to the "Parameters" section.

Water column samples for TCO2 and TA were collected in 250 mL BOD bottles following the protocols of Dickson et al. (2007) and poisoned immediately with 50 uL saturated mercuric chloride.

TCO2:

Samples were allowed to warm to room temperature prior to analysis, which was typically performed within 4 hours of collection. A volume of 1.25 mL of sample was acidified using an automated custom-built injection and bubble stripping system coupled to an infrared gas analyzer (LICOR LI7000). Integrating the infrared absorbance signal with respect to time for each stripped gas sample yields the total amount of CO2 evolved from the sample. TCO2 measurements were calibrated using certified reference materials (CRMs) obtained from Andrew Dickson at UCSD (Batch 122). CRM’s were run periodically as unknowns over the course of a run to constrain instrument drift. All unknowns were run in triplicate. Precision estimated on the basis of triplicate analysis of unknown seawater samples (>3500 runs) and CRM replicates (n=855) for NBP 1302 is ±3 umol kg-1.

Total Alkalinity (TA):

Samples were prefiltered through 0.45 um polyvinylidene fluoride filter and were typically analyzed within 12 hours of collection with a potentiometric titrator (Metrohm 855 Robotic Titrosampler). TA calculations follow Dickson et al. (2003). Measurements were calibrated using CRMs (Batch 122) and precision estimated on the basis of CRM replicates (n=108) is ±1.5 umol kg-1.

POC, PON, dC13_POM, dN15_POM:

POM was collected by filtering between 0.5 and 4 liters of seawater through precombusted (450C for 4.5 hours) Whatman GFC filters following the protocols of Knap et al. (1996). Filters were rinsed immediately after filtration with 10 mL of 0.1N HCl to remove calcium carbonate. The filters were air dried and analyzed shore-based using a Carlo Erba NA1500 Series 2 elemental analyzer coupled to a Finnigan Delta+ mass spectrometer with a ConFloII open split interface.

References:

Dickson, A. G., Afghan, J. D., and Anderson, G. C.: Reference materials for oceanic CO2 analysis: a method for the certification of total alkalinity, Mar. Chem., 80, 185–197, doi:10.1016/S0304-4203(02)00133-0, 2003.

Dickson, A. G., Sabine, C. L., and Christian, J. R.: Guide to best practices for ocean CO2 measurements, PICES Spec. Publ., 3, p. 191, doi:10.1159/000331784, 2007.

Knap, A., Michaels A., Close A., Ducklow, H., and A. Dickson: Protocols for the Joint Global Ocean Flux Study (JGOFS) Core Measurements, JGOFS Rep., 19, 1–170, 1996.

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.