mCP Chem Lab Cruise Blog
The GEOTRACES GP-17 OCE cruise is now complete. Read about the expedition below and come back in November 2023 when we embark on GEOTRACES GP-17 ANT!
Arriving in Punta Arenas, Chile, and demobilization
02/07/2023 18:22 UTC
By Ji-Young Moon
We finished the sampling and measurement at the last station, station 38, at the dawn of January 24th. And that morning, we entered the Strait of Magellan. We had about a day left before the arrival, and everyone was busy disassembling and packing their instruments. We arrived at the port of Punta Arenas, Chile, at 08:00 on January 25th. A beautiful rainbow welcomed us.
After arriving at the port, we sorted the laboratory stuff into containers by their destination. This includes packing laboratory gear into plastic or metal boxes, securing them with plastic or metal straps, wrapping, moving them with cranes, and sorting them into containers using forklifts. This work started the afternoon of the 26th and continued through the late night of the 27th. Strong winds and occasional rains in the Punta Arenas made the work challenging, but we finished it without delay because everybody worked so hard.
GP17-OCE expedition had a range of challenges, as it went through a rough Antarctic Ocean, but it ended up as a successful cruise, and we achieved most of our objectives. Thanks to all the people on the ship and land that contributed to the team effort that enabled us to overcome those challenges. We will continue our efforts by analyzing samples and writing manuscripts. I look forward to sharing our accomplishments in the post-cruise meeting. Farewell, Roger Revelle and all the folks in GP17-OCE!
What do people in the hydro lab do?
02/03/2023 18:12 UTC
By Ji-Young Moon
The R/VRoger Revelle has several laboratories, and the Woosley group analyzed seawater pHt samples in the hydro lab. People in the hydro lab usually collected seawater samples from ODF (Oceanographic Data Facility, at Scripps Institution of Oceanography) casts and worked on various scientific subjects ranging from primary oceanographic parameters to isotopic analysis.
I interviewed Andrew Barna of Scripps Institution of Oceanography at first. His principal duty on the ship was measuring dissolved oxygen (DO) concentration in the seawater sample from ODF casts. To measure DO, he added manganese chloride and sodium hydroxide iodide solutions to the known amount of seawater sample. Manganese hydroxide is oxidized by the dissolved oxygen in the seawater and precipitated, forming hydrated tetravalent oxides of manganese. Upon acidifying the sample, manganese hydroxide dissolves. The tetravalent manganese acts as an oxidizing agent, liberating free iodine from iodide ions. He calculated DO concentration by titrating the sample using a standardized sodium thiosulfate solution and measuring the amount of free iodine which is equivalent to the DO present in the sample. He also prepared the ODF rosette before it went down to the sea, maintained CTD sensors and Niskin bottles, and managed ODF datasets.
Jennifer L. Middleton from Columbia University collected seawater samples for He and He isotopes. Because He diffuses out of glass, she collected samples by air-tight sealing of copper tubes full of seawater. She is conducting collaborative research with the Woods Hole Oceanographic Institute. After the cruise, she will measure He concentration and isotope ratios in the lab in Woods Hole. The study on He in seawater has significant value as it is the indicator of the distribution of hydrothermal vents and can be used as a tracer of water circulation and water mass mixing.
John Calderwood, from Scripps Institution of Oceanography, analyzed samples for seawater practical salinity. Salinity was measured using a salinometer based on the conductivity of samples. He also managed various sensors loaded with the ODF rosette and underwater instruments. These included two conductivity (salinity) sensors, two temperature sensors, a third temperature sensor (measures temperature only at depths where we collect samples), a pressure sensor, a fluorometer, a photometer, transmissometer (provides information on the optical properties of the ocean, which is affected by particulate or colored dissolved organic matter, etc.), two oxygen sensors, oxidation/reduction potential sensor (detect signals from hydrothermal vents), and a turbidity sensor.
Susan Becker of the Scripps Institution of Oceanography measured concentrations of seawater nutrients (nitrate, nitrite, phosphate, and silicate) from ODF, GTC, and pump casts. Because concentrations of nutrients generally increase with depth, we could check with nutrient concentrations whether the niskin bottles from which we collected the seawater sample was miss-tripped or not. Also, nutrients themselves are essential for the growth and reproduction of phytoplankton, and thus they can be used as indicators of marine productivity. Nutrient concentrations are measured using the coulometric method. Mixing the sample with an indicator dye leads to a color change due proportional to the nutrient concentrations. We can calculate nutrient concentrations by measuring the color change (absorbance) with a photometer. The fundamental principle is similar to that of pHtmeasurement. A noticeable difference is that bubbles are used to isolate samples, and they help the seawater sample and indicator mix.
During the cruise, I spent the most time with people in the hydro lab. We sampled and analyzed in the same space. This cruise would have been much more difficult without them, as they have helped me in many ways. I appreciate all of you.
Life on the R/V Roger Revelle
01/21/2023 17:56 UTC
By Ji-Young Moon
We are currently working on station 36. We have less than a week to the end of the cruise. I have lived on R/V Roger Revelle for 50 days so far, and today, I’d like to introduce what life on the ship is like.
There are two people per room. Each room has a bunk bed and blackout curtains. Everyone can sleep whenever they want, as roommates can have different schedules for work. The ship provided bedding, including pillows, blankets, and bed sheets. Every room has a desk, chair, couch, and washstand. Two rooms share a shower and toilet. There is plenty of storage space, including two large closets and drawers below the bed. All drawers have auto-lock, to keep them from opening as the ship rolls. Because small items can fall to the floor from the ship’s rolling, the floor is made of soft carpets. There are lights in the ceiling and ones next to the closet and washstand, so we can use the room without turning on the ceiling light while your roommate is sleeping. There are also four electrical outlets on the desk and one per bed. Rooms are ventilated and temperature-controlled by a 24-hour air conditioning system. Each person has one set of life jackets and immersion suits in the room in case of emergency.
Common spaces include a galley, library, lounge, and laundry room. We have meals in the galley, and everyone meets at the fixed mealtimes. If I cannot come to a meal because of work, I can ask others to save me a plate for later. There is a big desk in the library, and people can work with data or documents with their laptops. There is a large monitor in the lounge, and we had several science meetings. People can also watch movies there. There are two washers and four dryers in the laundry room. Detergents are provided by the ship, and we should get our clothes as soon as possible after using them because others can be waiting for them!
Before the cruise, I had been worried about living on the ship, but it seemed more doable than I thought. If you are ahead of a cruise, I hope this post helps you.
Trace metal-clean bubbles on the ship
01/20/2023 02:30 UTC
By Ji-Young Moon
We headed North and are working on station 35, located at 54˚S. This cruise, GP17-OCE, is part of the GEOTRACES program, an international program studying trace elements and isotope cycles in the marine environment. Deep-water trace metal samples require handling to study, as they can easily be contaminated, even by the atmosphere. As a part of those environments, there are “bubbles” constructed in the labs. To figure out what bubbles are, I interviewed Yerim Kim. She is a Ph.D. student at Texas A&M University and works as a Supertech inside the bubble.
- How is a bubble different from the external environment?
Bubbles are assumed to be particle-free environments wrapped with a plastic sheet. A positive pressure filtered with a HEPA filter to remove particles inside the bubble and block particle influx from the outside.
- What happens inside the bubbles?
We do most of the science [where] particles can contaminate the seawater sample, such as trace metal-clean sampling and ultrafiltration.
- Which parameters are samples in the bubble?
Most of the trace metal parameters. For example, Zinc ligand, Mercury, Iodine, Barium, trace metal concentration], Trace Metal Isotopes of Nickel, Copper, Iron, etc., etc.
- Please introduce your research interest in brief.
I aim to study water mass transition and the influence of anthropogenic activity in the Southern Pacific and Antarctic Oceans using Pb isotope ratio.
Meeting people from various research areas and learning about their studies is one of the pleasures of the cruise. Thanks again to Yerim Kim for taking time out of your busy schedule!
How do scientists collect seawater from the ocean?
01/10/2023 03:39 UTC
By Ji-Young Moon
We are currently on station 27 on the 67°S line. How do marine scientists work in the ocean? There are 38 stations in this expedition. The depth of the ocean in this area is 3000-5500 m (about 2 – 3.5 miles). The stations consist of several different types: super, full, and demi stations determined by geologic and biogeochemical importance. On super stations we collect samples at 37 depths, full stations have 25 depths, and demi stations have 13 depths. The more depths a station has the deeper into the water column we collect samples.
Science operations are 24 hours while on station, and when the work is done, we move to the next station. Each team has is researching a different parameter and each has a different way to collect samples from the ocean without contaminating the sample. Our research team collects seawater samples from ODF (Ocean Data Facility) rosette, or non-trace metal clean rosette.
The ODF rosette consists of 36 Niskin bottles and several sensors including the CTD (conductivity, temperature, and depth). Each Niskin bottle is deployed to the ocean with elastic strings holding its lids open on each end, allowing water to flow through the bottles as it moves through the water column. We hang it on a winch and send it down into the sea, determining sampling depth while measuring the biogeographic characteristics of the seawater with various sensors in real time.
As sampling depths are determined, we close the lid of Niskin using the ratchet operated by an electrical signal at the desired depth while the rosette is brought up. This captures water from the desired depth without any headspace in the bottle. After lifting the rosette on the ship, researchers start to sample the seawater. The seawater properties from the deep ocean starts to change as it meets the air due to gas exchange because the headspace in the Niskin bottle grows as water is sampled from the Niskin. There is a sampling order determined in part to how fast the parameter is affected by the gas exchange. Researchers get seawater samples in that order to minimize the possibility of contaminating the sample.
As I described above, scientists here are working day and night. For the rest of the cruise, I hope everyone can complete the work while caring for their health.
Christmas and New year on the ship
01/07/2023 05:26 UTC
By Ji-Young Moon
We left station 25, heading east to station 26. Our journey is now over two third complete. The weather and seas became calm after we entered the Antarctic Circle. We see lots of icebergs around the ship and sometimes meet whales.
A few days ago, we welcomed Christmas and New Years on the ship. At that time, we were crossing a region where biogeochemistry sharply changes across latitude. Thus, we were all very busy, but everyone set aside time to prepare for small events. A few days before Christmas, the science party decorated labs with colorful light bulbs, Rudolph, and small trees. On Christmas eve, one of chief scientists handed out small pouch with presents, such as a small penguin doll and candy canes. There was white elephant gift exchange event on Christmas morning. People put on Santa and Elf costumes, and had a pleasing time enjoying the event. In the moment it turned into a new year, we celebrated 2023 with ball drop event!
It’s a bit late but let me send greetings for Christmas and New Year. In my home country, we make a wish when it is a new year. I wish everybody in this ship will complete this cruise safely and smoothly.
Measurement of the pH of seawater using the indicator dye m-cresol purple
12/31/2022 18:41 UTC
By Ji-Young Moon
We are keeping up with the expedition and have reached station 20. Though we met rough weather, we have continued our journey. One of the scientific duties of the Woosley group in this expedition is collecting and measuring seawater pH samples.
We are using the spectrophotometric method to measure the pH of seawater on the total hydrogen ion concentration scale. In this procedure, we use the indicator dye m-cresol purple. The principle in this approach is that the indicator dye has different forms depending on the bonding with hydrogen ions (I2– and HI–), and those two forms have substantially different absorption spectra (i.e. colors). The ratio of the two forms varies with pH. Therefore, we can calculate pH from the ratio of those two forms of indicator ([I2–]/[HI–]) using a specially calibrated equation.
I poison the seawater pH samples using a mercuric chloride solution right after collecting them in order to prevent biological activity of marine microorganisms from altering the pH. Then I seal them with rubber caps and aluminum seals. Since pH is very sensitive to temperature, all samples are warmed to 25.0 °C (± 0.1 °C) in the thermostated water bath for an hour. A sample is injected into the spectrophotometric system by an automatic injection apparatus. At first, the reaction cell is rinsed. Then a blank, seawater without any indicator, is measured. The system mixes a portion of the sample and indicator dye and injects the mixture into the reaction cell. Next, the absorbances are measured at the wavelengths corresponding to the absorption maxima of the I2– and HI– of the dye (578 and 434 nm, respectively) and at a non-absorbing wavelength (730 nm). We can calculate the pH extremely precisely (pico-molar, 10-12, levels) from the ratio of the absorbances and an equation calibrated on the total pH scale.
As we progress to the South, I can see the changes in the depth profile of seawater pH indicating changes in the water masses we are crossing. We hope to complete the data set during the second half of the cruise!
Currents in the Southern Ocean
12/25/2022 00:13 UTC
By Ji-Young Moon
We entered south of 50°S and are in transit to station 15 located at 54°S. Weather is getting cold, and we are about to enter the subantarctic front. The Southern Ocean is one of the major regions of our expedition. It surrounds the Antarctic continent and significantly affects global climate. Geographic boundaries defining the Antarctic Ocean are not clearly defined, but it is generally considered the oceanic regions south of 50°S. The Antarctic Ocean consists of subbasins such as Ross Sea, Weddell Sea, Bellingshausen Sea, Amundsen Sea, and Davis Sea.
Strong westerly (eastward) winds dominate around Antarctica. In the southern hemisphere, glaciers and currents move in a direction perpendicular to the left of the wind. This phenomenon is called ‘Ekman transport’. In the region where westerly winds blow, Ekman transport moves water toward the equator, making a pressure gradient towards the polar regions. These pressure gradients generate eastward ocean currents in the Antarctic Ocean, creating the Antarctic Circumpolar Current surrounding the Antarctic continent. The Antarctic Circumpolar Current blocks warmer seawater originating in low latitude regions from approaching the Antarctic region and help maintain the large glaciers in the Antarctic.
A few days ago, we met two penguins. We haven’t entered the Antarctic region yet, so we guessed that they came with the recent storm. As we sail further south, we are expecting to see a lot more penguins!
What is pH and Ocean Acidification?
12/09/2022 05:21 UTC
By Dr. Ji-Young Moon
We embarked on December 1st, so today is the 8th day of the cruise. We are currently on science station #3 located at approximately 26˚S in the South Pacific Ocean. Part of my research on this cruise involves collecting seawater pH samples and analyzing them onboard. The pH is a measure of the acid/base balance in a solution. In chemical oceanography, the definition of pH is slightly different from the conventional one because of the high ionic strength (i.e.salinity) of seawater. A widely used definition is total scale pH (pHT). It is defined to account for the effect of both protons and hydrogen sulfate ions.
Since the start of the Industrial Revolution, the carbon dioxide (CO2) concentration in the atmosphere has rapidly increased as a result of burning of fossil fuels, cement production, and land use change. However, more than one-fourth of CO2 has dissolved in the oceans, slowing the accumulation of CO2 in the atmosphere. CO2 acts as a weak acid in seawater, thus the uptake of anthropogenic CO2 shifts the acid/base balance of seawater resulting in a decrease in pH; A process termed ocean acidification (OA). However, OA does not mean that the pH of the ocean will drop below 7.0 and become acidic, only that that the acidity is increasing. The preindustrial surface ocean pH was ~8.2, today it is approaching 8.05. That may sound like a small drop, but it is approximately a 40% increase in acidity because pH is on a log scale. Under many business-as-usual scenarios, the pH is predicted to decrease by another 0.25 – 0.35 units by the end of the century, an increase in acidity of up to 200%!
OA impacts many organisms in the marine environment. The most representative case would be organisms with calcium carbonate skeletons or shells. These include organisms like pteropods, sea urchins, mussels, oysters, gastropods, and corals. The ability of organisms to build their calcium carbonate skeletons and shells is hampered as the concentration of carbonate ions in seawater decrease. OA can also have detrimental impacts on non-calcifying organisms, particularly larval and juvenile stages. As a state variable, decreases in pH can result in other changes to seawater chemistry, such as speciation of trace metals which can be minor nutrients for organisms. Thus, OA has wide ranging impacts on ocean chemistry and marine ecosystems. Part of my research on this cruise is to monitor and quantify the uptake of CO2 and resulting decrease in pH.
7-day quarantine before departing for oceanographic expedition
11/25/2022 19:52 UTC
By Dr. Jiyoung Moon
In the pandemic era, we need extraordinary caution for the oceanographic expedition because many people share the living and working space in the limited area of the ship. The Scripps Institute of Oceanography operating the R/V Roger Revelle has notified us of the covid protocol for minimizing the risk of the pandemic both before and after boarding. All of the people on board, including ship crews and scientific parties, must follow the protocol. Before departing for Tahiti, where the expedition will start, I have to submit the covid vaccination certificate, including the bivalent booster and the negative result of a RT-PCR test. I also paid special attention to following pre-boarding safety measures, such as avoiding crowded public spaces and wearing a mask (N-95 or KN-95) in indoor and crowded outdoor public places (Table 1).
| When | Action Required |
| 14 days prior to boarding | • Submit COVID-19 vaccination documentation to SIO• Bivalent booster required• Begin pre-boarding health safety measures• RT-PCR test before flying to Papeete |
| 7 days prior to boarding date | • Begin quarantine in the port of embarkation• Track symptoms using daily health assessments |
| 2 days prior to boarding date | • Obtain a COVID-19 RT-PCR test.• Before boarding, email results to SIO |
| During public transportation | • Wear an N-95 or KN-95 mask |
| Boarding date | • If you have reported your COVID test results, and if you have no COVID symptoms, proceed to the ship.• The ship will administer an antigen self-test when you arrive at the gangway. Before you board, take the test and show your results to the gangway watch officer. Do not go aboard until you have provided negative test results. |
There were two options regarding the pre-boarding quarantine. One option was a 7-day quarantine from Nov 22nd in Tahiti, and the other was staying in the ship leaving San Diego on Nov 13th to Tahiti, being exempted from the quarantine. I chose quarantine and headed to Tahiti on Nov 21st by flight (Figure 1). Today is Nov 25th, the fourth day of quarantine. I go out of the accommodation once a day to dispose of trash and one or two times a day to get food delivery. This situation is sometimes challenging, but I expect everyone is trying to enjoy the time of quarantine.
There are also COVID safety protocols after boarding. Everyone will get antigen tests when boarding, for the first seven days, and on the tenth day at sea. We will wear masks in indoor spaces. We will practice extra caution in personal hygiene by washing and sanitizing hands and surfaces. Mask requirements and dining restrictions are lifted if everyone gets negative results on the tenth day at sea.
Those safety protocols were also followed during mobilization a few weeks ago. I appreciate the Scripps Institute of Oceanography and all boarding members who are making an effort for everyone’s safety.
Setting up for the GP17-OCE expedition
11/15/2022 21:47 UTC
By Dr. Jiyoung Moon
The RR2214 research cruise aboard the R/V Roger Revelle, a meridional section of the Pacific as part of the GEOTRACES program, is a 55-day expedition consisting of 38 planned stations. The leg will begin in Papeete, Tahiti, crossing the south Pacific Ocean to the ice edge of West Antarctica. Then heading east before crossing northeastward towards Punta Arenas, Chile (Figure 1). The chief objective of this cruise is to determine the sources, distributions and sinks of trace elements and isotopes and their interactions with biological productivity and carbon cycles in the South Pacific Ocean. Various scientific groups will work together to achieve the primary goal, using analytical methods of biogeochemistry and marine chemistry. Ultimately, the deliverables from this research cruise will enhance our understanding of the biogeochemical cycling of trace metals and carbon, processes controlling their distributions, and their interactions with marine environments and ecosystems under climate change.
Our research team will be sailing on the RR2214 cruise, aiming to fill the knowledge gap on the connection between the dissolved inorganic carbon system and the trace elements in the South Pacific Ocean. To do so, we will collect data on dissolved inorganic carbon parameters (pH, dissolved inorganic carbon, total alkalinity) by measuring seawater pH onboard and collecting seawater samples for dissolved inorganic carbon and total alkalinity. We are excited to see how the change in trace metal abundances affects the productivity of the phytoplankton community, changing the carbon dynamics in the study region. Moreover, we will assess long-term variabilities in anthropogenic carbon storage and ocean acidification to see the ocean’s response to rapid environmental changes ongoing in the study region. Our research would contribute to assessing the current state of air-sea carbon dynamics and will provide clues on how future climate change will alter the global ocean.
We participated in the mobilization at the Nimitz Marine Facility in San Diego from November 9th to 12th. Shipping containers for scientific gears and ship stores were loaded onto the deck with the large shore crane during mobilization. Some research groups participated in making bubbles, a trace metal clean space preventing contamination of the sample by using filters to remove small particles from the air. Another priority was to secure their scientific gear, so they will not injure anyone or anything during the roll in the sea (Figure 3).
The research vessel departed San Diego on November 13th and will meet most of the scientific party in Papeete. Stay safe until boarding!