Table of Contents

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

These data are part of a manuscript submitted to Continental Shelf Research:

Goñi, M.A., Welch, K.A., Alegria, E., Alleau Y., Watkins-Brandt, K., White, A.E. (submitted) Wintertime Particulate Organic Matter Distributions in Surface Waters of the Northern California Current System. Continental Shelf Research.

The data are shown in figures in the manuscript (Figures 6, 8 and 9).

Full details for collection and analyses of underway POM samples are provided by Holser et al., 2011 and Goñi et al., 2019 and Goñi et al., submitted. Brief summaries are provided below.

Samples for this study were collected aboard RV Oceanus using the surface underway scientific system.

Aboard the vessel we had access to uncontaminated seawater and collected samples at specific times that allowed us to determine location (latitude and longitude) and seawater characteristics (temperature and salinity) from the ships’ navigation and sensor panels. We used a semi-automated filtration system (SAFS) described by Goñi et al., (2019) connected to Oceanus surface underway water to collect particulate organic matter samples. Surface underway water was connected to the SAFS through a manual flow-control valve via opaque polyethylene tubing.  A fly wheel flow meter was placed in-line and connected to a laptop computer using a data acquisition system to measure and record flows during the filtration stage. A switching valve with 8 ports was placed downstream from the flow meter and controlled by the laptop.  Under stand-by conditions, flow was directed to the ‘waste’ port, which was fitted with unobstructed tubing that drained into one of the ship’s sinks and flowed back to sea.  The 8-sample ports were fitted with tubing, quick-turn sockets  and in-line stainless steel 13-mm Swinney filter holders.  The flow from these filters was directed to the same sink as the ‘waste’ flow.  In each holder, we placed one pre-combusted (400 oC for 3 hours) 13-mm glass fiber filter supported by a stainless steel screen and locked into place with a Teflon o-ring that prevents leakage and results in a filtration area of 78.5 mm2. Once filters were fitted in each of the sample ports, the filtration program was started to collect samples at selected intervals.

Once the filtration run was completed, the filter housings were removed from the SAFS, opened, and each individual filter folded into pre-cleaned silver capsules, which were placed into sample trays that were frozen until CN analyses.  Each sample was assigned a specific time stamp (start-end of filtration process) that coincided with the ship’s clock and allowed us to retrieve location and oceanographic data for each sample, as well as determine an overall filtration volume, which was used to calculate particulate nitrogen and carbon concentrations once their contents were determined.  During normal operations, we stacked two filter holders at specific positions in order to collect both particles from a sample using the first filter as well as measure blanks associated with dissolved organic matter sorption as filtered water goes through the second filter.

Carbon and nitrogen analyses were conducted using high temperature combustion/reduction according to Holser et al., 2011 and Goñi et al., 2019. Sample and blank filters were exposed to concentrated hydrochloric acid fumes to remove carbonates and run in two CN analyzers (NC2500 Thermoquest and ECS 4010 Costech) using the manufacturers’ recommendations for carbon and nitrogen analyses (e.g., specified temperatures for combustion and reduction furnaces, O2 loops/pressure, and the use of a water trap). In each run of a full auto-sampler, we typically included 6 standards (e.g., cystine, atropine) with different and known amounts of carbon and nitrogen to develop distinct calibration curves for each run. All filters were treated the same and we used the DOM blanks to correct for DOC and DN sorption. Detection limits for OC and N were 0.04 and 0.03 micromoles, respectively. Replicate analyses of selected samples yielded average standard errors for both measurements of ~2% of measured values.

References cited: Holser et al., 2011; Goñi et al., 2019; Goñi et al., submitted.

Data were acquired at approximately 1 Hz and then binned to correspond to the time stamps of discrete POM samples collected by the semi-automated filtration system (SAFS, see above). The transmission (Tr) data from the C-Star instrument (r = 0.25 m) was converted into beam attenuation coefficients (c = lnTr/r; m-1), which represent the sum of attenuation due to particles, water and colored dissolved organic matter. Particle beam attenuation data (Cp) were determined after correcting for the latter two by conducting attenuation measurements in low POC waters from offshore regions to adjust measured beam attenuation by an offset (e.g., Gardner et al., 2006). In the winter cruises, we verified these corrections by measuring beam attenuation signals of particle-free waters that were filtered through a 0.2 mm membrane filter (White et al. 2017; Slade et al. 2010). Navigation data were integrated into the sensor data set using the sample filtration time stamps to provide latitude and longitude information for each surface underway sample.

BCO-DMO processing notes:

• Concatenated all cruises
• added ISO_DateTime_UTC column
• Adjusted column names to comply with database requirements
• Adjusted all Date_Time_PST rows to following notation: mm/dd/yyyy HH:MM

NSF Award Abstract:
As is true for many coastal regions worldwide, the Pacific Northwest margin is characterized by intense seasonal contrasts in conditions controlling carbon flux between the atmosphere, land, and ocean. During the wintertime, rapid and intense flooding of small coastal rivers and the associated inputs of freshwater, nutrients, and organic matter are commonplace in the Pacific Northwest. Impacts of these wintertime terrestrial-ocean transfers by small, flood-prone rivers on the upwelling regions, such as the Pacific Northwest, have been underestimated at both global and regional scales. In order to gain a complete and predictive understanding of carbon cycling in ocean margins, the biogeochemistry of periods of intense terrestrial-ocean transfers needs to be comprehensively studied. This project will evaluate the dynamics of organic matter cycling along an upwelling-dominated margin during the wintertime period of active terrestrial inputs and biological cycling using a combination of shipboard, glider, moored and remote measurements. New developments in ocean observational technologies through the Ocean Observatories Initiative (OOI)* and existing scientific infrastructure along the Oregon coast will be instrumental in achieving this goal. This work will provide research opportunities for undergraduate and graduate students, and outreach will be conducted through the Centers for Ocean Science Education Excellence Pacific Partnership, local coastal community colleges, and interpretative centers such as Oregon State University Hatfield Center, the Umpqua Discovery Center, and Oregon Coast Aquarium in an effort to educate students and the public about the research.

Globally, most studies of carbon cycling in eastern boundary regimes have focused on the upwelling phase during the summer months, resulting in a much poorer understanding of non-upwelling periods. As is many coastal upwelling systems, wintertime conditions along the Pacific Northwest margin are characterized by southerly, downwelling-favorable winds and moisture-laden storms that result in seasonal flooding by the numerous small to medium-sized rivers in the region. Elevated discharges by these coastal rivers translate into large inputs of land-derived biogeochemical relevant constituents, including freshwater, dissolved inorganic nutrients, and dissolved and particulate organic matter, which collectively rival or exceed those of the Columbia River. To understand the impact of flood-derived terrestrial inputs on the biogeochemistry of the coastal zone along the Pacific Northwest margin, researchers will conduct a detailed investigation of biogeochemical processes in the water column along the Newport Hydrographic Line off the central Oregon coast during fall/winter conditions. The project includes an intensive field effort that takes advantage of ship-based and autonomous platforms to gain comprehensive wintertime coverage. Among the project outcomes, this effort will lead to a revised paradigm of the biogeochemical drivers of carbon cycling in coastal margins.

*The Ocean Observatories Initiative (OOI) is an NSF-funded, networked infrastructure of science-driven sensor systems to measure the physical, chemical, geological and biological variables in the ocean and seafloor. For more information about OOI, please visit the website: www.oceanobservatories.org