A Pomona – Pitzer team is participating in an oceanographic research cruise in the Eastern North Pacific. This is the first blog post from our students on the cruise.
The project “Dissolved Organic Nitrogen Transport and Utilization” dubbed as DONUT is funded by the NSF Chemical Oceanography Program to study how a special nutrient, Dissolved Organic Nitrogen” or DON, support phytoplankton growth in the one of the largest ecosystems on earth, the Pacific Subtropical Gyre. DON has been considered a nutrient not typically available for algae in the ocean. But recently, evidence started mounting for DON being the main source of nitrogen in oligotrophic, nutrient poor areas of the ocean, such as Subtropical Gyres. The teams from University of New Hampshire, Texas A&M, University of Minnesota and Pomona College set out to figure out how much of the plankton growth relies on DON as a main source of nitrogen. After more than a year of preparation, the teams are now at sea.
Pomona team includes two students, Elle Hawthorne, rising sophomore of Pomona College, and Charlotte Renner, rising senior of Pitzer College, and co-Principal Investigator, Visiting Assistant Professor of Geology Department, Maria Prokopenko. Elle is supported by Pomona SURP funding, and Charlotte will be doing her senior thesis project with Prof. Prokopenko, interpreting the data collected on this cruise.
Elle and Charlotte are keeping the blog, where they are reporting weekly on our North Pacific Adventures. See what they have to say!
Week 1: June 21st - June 28th
And we’re off! The RV Kilo Moana departed San Diego on Sunday, June 21 — the last time we would see land for another month. We spent two days loading in the Port of San Diego, setting up in the labs, assembling the instruments, getting acquainted with each other. Two Pomona technicians, Austin Cordova and Kyle McCarthy helped us to set up and waved us goodbye.
Within the first few hours, we arrived at station one and were ready for a full day of sampling. The science crew consisted of 17 people — a mixture of professors, students, and technicians. On board, there are participants from eight different academic institutions: in addition to four original teams, groups from Scripps Institution of Oceanography, University of South Florida, Stanford and University of Southern California are participating, all with their own unique missions for the next four weeks. The research includes biogeochemical, organic geochemistry, molecular biology and isotopic studies.
In the first few days, one of our main responsibilities was assisting Professor Prokopenko with the setup of the Membrane Inlet Mass Spectrometer (MIMs), an instrument that constantly measures the concentration of different gases in water. For this cruise we are focused on the O2/Ar ratio as an indicator of biological productivity. As the boat moves, water from the underway is pumped through the systems to give us O2/Ar measurements along the ship’s path. We collected samples from every station using the Conductivity Temperature Depth (CTD) Rosette, which allowed everyone to obtain the water they needed from different depths — the deepest of this week being around 4,000 meters.
We also learned how to filter this seawater, measuring particulate organic carbon and nitrogen to get insight into primary productivity. In the first week, we filtered around 500 liters of seawater! We even found a copepod who had survived the trip from 1,000 meters below the surface (don’t worry, we released him back into the ocean!). Finally, we learned how to collect samples for N2O gas which will be analyzed after the cruise by Professor Manning at UCONN. Jen Karolewski, lab technician from Stanford, taught us how to ensure the samples do not have bubbles and preserve them with NaOH. These samples are taken from both the underway (typically every 4 hours) and from the CTD.
This week, we learned a lot of fundamental sampling techniques and got the opportunity to learn from many different scientists. We will talk about the work other teams are doing in the next installment of this blog. We also saw a lot of wildlife, including fish, seabirds, sharks, and a lot of copepods!