Thursday, May 30, 2019 – Collecting water samples before transiting southward
PUPCYCLE Log – Day 07: The Bubble Lab
We started the day offshore and southwest of the Oregon–California state line collecting more water samples from a broad shelf region of the California Upwelling Zone. Each research group uses a variety of methods for collecting their water samples, based on the organisms or
Figure 15 – Logan Whitehouse (UNC-CH) adds liquid nitrogen to a freeze-dried container where the filters are sealed and flash frozen for storage in -80 C degrees and RNA-sequencing (transcriptomics and proteomics) after the cruise. [Image credit: Miriam Sutton]particles they are investigating. The Phytoplankton scientists use the CTD (described on Day 02: Saturday, May 25: Phytoplankton Chillin’ with the UCBC!) and an Underway System that draws water from the surface continuously during the research cruise through tubing that feeds directly into their instruments on the ship. Each sample of water from the CTD is transferred to containers and taken to the shipboard lab for filtration. Filters capture the microorganisms and are sealed in small vials before being flash-frozen using liquid nitrogen. (Figure 15) The Underway System provides a steady stream of water to the FIRe Machine and other sensors as they monitor the phytoplankton and nutrients found during the R/V Oceanus’ transits between each study site. (See Day 05: Tuesday, May 28: Insights into PUPCYCLE 2019)
The scientists studying trace metals and dissolved particulates use different equipment to collect their water samples. Claire Till (Humboldt State University) is investigating 13 trace metals found in seawater. Seven of these are micronutrients used by marine organisms and include: Iron (Fe), Manganese (Mn), Copper (Cu), Cobalt (Co), Cadmium (Cd), Nickel (Ni), and Zinc (Zn).
Figure 16 – Kate Kouda (R/V Oceanus) guides the ship’s line as Ben Freiberger and Matt Hurst attach the GoFlo® bottle to collect water samples. [Image credit: Miriam Sutton]The additional six trace metals are not micronutrients in the aquatic food web but can provide insights into other oceanic processes, such as scavenging, where dissolved elements attach to other dissolved particles before sinking. These include: Lead (Pb), Gallium (Ga), Cerium (Ce), Yttrium (Y), Lanthanum (La), and Scandium (Sc). Claire noted that much remains to be learned about the trace metals adding, “Scandium is chemically similar to iron but is not a nutrient.” She suspects that Scandium might act as a substitute for iron, causing interference in the iron uptake by diatoms and other phytoplankton. Claire is hoping to learn more about Scandium during PUPCYCLE 2019 to see if this type of relationship exists.
Since many of the metals they study are also found in the ship and shipboard materials, the scientists use specially designed equipment, including a Teflon-coated GoFlo® system to keep these metal contaminants away from their samples. The GoFlo® system is designed to collect water through a GoFlo® bottle (similar to the CTD Niskin bottle) attached to a nonmetal line and lowered into the water column. Once the selected depth has been reached, a signal is activated for the GoFlo® bottle to close and capture the water. However, rather than receive an electrical signal from a computer through wiring on the ship, the bottle is
Figure 17 – Claire Till, Matt Hurst, and Travis Mellett prepare their water samples inside the “Bubble Room”. [Image credit: Miriam Sutton]triggered to close using a “messenger,” which is a heavy plastic device that is added to the line and then released to slide down the line until it hits the GoFlo® bottle, triggering the bottle to close and sealing the water sample inside. After retrieval, the filled bottles are removed from the line and taken to the “Bubble Room” where researchers prepare the samples for storage and transport off the ship at the end of the cruise. The trace metal analyses will take place at the university’s “bubble room” after the cruise. The dissolved and particulate samples will be filtered and/or prepped for storage for analysis after the cruise.
Claire Till was born in Newton, MA and received her undergraduate degree in Chemistry from Bates College (Lewiston, ME). She completed her PhD at the University of California – Santa Cruz in Ocean Sciences and is currently at Humboldt State University.
Today’s Certificate Challenge: Why are the Trace Metal and Dissolved Particulate researchers conducting their data collection inside the “Bubble”?
