Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

In situ pump filtration was performed using large volume pumps (WTS-LV; McLane Research Laboratories, Inc.) outfitted with mini-MULVFS (Multiple Unit Large Volume in-situ Filtration System) filter holders (Bishop et al. 2012). Pumps were loaded with filter stacks of either 3 filter pore sizes (51- and 5-um acid cleaned Nitex screens and 1 um pre-combusted quartz fiber filter) or 4 filter pore sizes (51- and 6-um acid cleaned Nitex screens, a double layer of 1 um pre-combusted quartz fiber filters, and a double layer of 0.3 um of pre-combusted glass fiber filters). Samples were frozen at -80 degrees Celsius until laboratory analysis. Sediment trap collection was performed using surface tethered sediment traps (STT) and neutrally buoyant sediment traps (NBST). Particles were collected in polycarbonate tubes with a collection area of 0.0113 m² and triggered to close at the end of the sampling period. Samples were collected in 500 mL of 70 ppt salinity, 0.1% formaldehyde-poisoned brine, buffered to pH 8.5 with borate and overlain with 1‑um filtered surface seawater. After collection and allowing particles to sink to the bottom of the tube on board the ship for an hour, brine was filtered through a 335‑um polyester screen and rotary wet split onto pre-combusted glass fiber filters with a pore size of 0.7 um. Samples were frozen at -80 degrees Celsius until laboratory analysis.

6 um and 51 um Nitex filters were washed down onto 0.7 um GFFs and inspected using a dissecting microscope, removing foreign (non-natural) material. Samples were freeze-dried and then stored at -20 degrees Celsius for the remainder of preparation. Samples were hydrolyzed using 6N HCl at 110 degrees Celsius for 20 hours, filtered, purified (to remove organic molecules other than amino acids and amino acid like molecules) using cation exchange chromatography. Amino acids in samples were derivatized to their isopropyl ester-trifluoroacetyl derivatives in a two-step derivatization: esterification with 4:1 isopropanol:acetyl chloride (110 degrees C, 60 minutes) and acetylation with 3:1 dichloromethane:trifluoroacetic anhydride (100 degrees C, 15 minutes), with the headspace exacuated with N₂ prior to each reaction. They were de-salted using phosphate buffer and chloroform and then re-acetylated. The solvent was exchanged for ethyl acetate immediately prior to analysis.

Analyses were carried out using a Thermo Fisher Scientific Trace 1310 Gas Chromatograph (GC) coupled to a MAT 253 Plus Isotope Ratio Mass Spectrometer (IRMS) through a Thermo Fisher GC Isolink II system with a combined oxidation/reduction reactor held at 1000 degrees C, a liquid nitrogen trap, and a Conflo IV open split interface.

Data Processing:
Data were processed through Thermo Fisher Isodat 3.0 and Microsoft Excel.

BCO-DMO Processing:
- replaced "n/a" with "nd" as missing data value ("no data");
- replaced hyphens with underscores in parameter names to comply with BCO-DMO naming conventions;
- changed all date fields to format YYYY-MM-DD.

NSF Award Abstract:
The biological pump is largely responsible for the vertical transport of organic carbon from the surface to the ocean interior. However, only a small fraction of organic material produced in surface waters is sequestered in the deep ocean. The rest is consumed, or respired, by bacteria and larger organisms. The overarching goal of the proposed work is to characterize the relative influences of bacteria versus larger organisms on the degradation of organic material with depth. Guided by recent results from the subtropical Pacific, the investigators will use measurements of stable isotopes of nitrogen in different amino acids (compound-specific isotopic analysis of amino acids, known as AA-CSIA), along with measurements of the abundances of different forms of amino acids, and other parameters derived from these analyses to identify how the partitioning and flux of large and small particles are affected by different degradation processes. By improving the interpretive power of the AA-CSIA technique the investigators propose to determine: 1) the relative importance of microbial and zooplankton consumption on the efficiency of the biological carbon pump in the subarctic northeast Pacific, and 2) how much microbially-altered small particles fuel the metabolisms of mid-water zooplankton. This work capitalizes on an existing, comprehensive field program (NASA EXPORTS) specifically focused on building a predictive framework relating surface ocean properties to the vertical flux of organic carbon. The tremendous amount of data to be collected on all aspects of the biological pump as part of the EXPORTS program will aid the development and interpretation of the investigators' amino acid isotopic tool. Results will be broadly communicated via production and distribution of several episodes of Voice of the Sea, a local television program that will air in Hawaii and across many Pacific islands. Episodes also will be posted online and publicized through social media to the south Florida community. This project will support a Ph.D. student and an undergraduate student at University of Miami, which serves a 25% Hispanic population, and an M.S. student and an undergraduate student at University of Hawaii, which is a designated minority-serving institution.

The proposed work introduces a new geochemical framework to distinguish microbial versus zooplankton alteration of marine organic matter. Piloted on samples from the subtropical Pacific, this approach interrogates unamended sinking material directly, using amino acid compound-specific isotopic analysis (AA-CSIA) to determine the progressive, cumulative impact of microbial and zooplankton degradative pathways. The proposed work (1) will extend this interpretive framework to explicitly define end-member signatures such as fecal pellets and will apply this refined method to a study site in the subarctic northeast Pacific to (2) determine the vertical progression of degradative mechanisms in an oceanographic location with contrasting productivity and vertical length scales of flux attenuation and (3) determine whether microbially- degraded biomass is important for fueling midwater metazoans under contrasting carbon flux conditions. The proposed work will be conducted in collaboration with the NASA EXPORTS program at the Ocean Station Papa time-series site. Teaming with this program presents a unique opportunity to refine AA-CSIA interpretation in parallel with intensive data collection defining productivity, particle size distribution and flux, and numerous biological parameters. In comparing subtropical and subarctic Pacific locations, the proposed work will test how differences in productivity and plankton community structure influence vertical patterns of consumption and alteration of phytodetritus by microbes and zooplankton, from surface to mesopelagic depths.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

EXport Processes in the Ocean from Remote Sensing (EXPORTS) is a large-scale NASA-led field campaign that will provide critical information for quantifying the export and fate of upper ocean net primary production (NPP) using satellite observations and state of the art ocean technologies.

Ocean ecosystems play a critical role in the Earth’s carbon cycle and the quantification of their impacts for both present conditions and for predictions into the future remains one of the greatest challenges in oceanography. The goal of the EXport Processes in the Ocean from Remote Sensing (EXPORTS) Science Plan is to develop a predictive understanding of the export and fate of global ocean net primary production (NPP) and its implications for present and future climates. The achievement of this goal requires a quantification of the mechanisms that control the export of carbon from the euphotic zone as well as its fate in the underlying "twilight zone" where some fraction of exported carbon will be sequestered in the ocean’s interior on time scales of months to millennia. In particular, EXPORTS will advance satellite diagnostic and numerical prognostic models by comparing relationships among the ecological, biogeochemical and physical oceanographic processes that control carbon cycling across a range of ecosystem and carbon cycling states. EXPORTS will achieve this through a combination of ship and robotic field sampling, satellite remote sensing and numerical modeling. Through a coordinated, process-oriented approach, EXPORTS will foster new insights on ocean carbon cycling that maximizes its societal relevance through the achievement of U.S. and International research agency goals and will be a key step towards our understanding of the Earth as an integrated system.