The barrenness of life and other particulate material in the clear waters of the central South Pacific allows light to penetrate more deeply than anywhere else. Columbia graduate students Frankie Pavia and Sebastian Vivancos are part of an international team of scientists studying the chemistry and biology of the South Pacific on the FS Sonne. They will try to determine input and removal rates of metals and trace elements from the ocean, which are crucial to our understanding of ocean life and past climates.
How far is five kilometers, vertically? We leaned over the edge of the boat, staring into the water, watching the last glimmer of light from the in-situ pump disappear into the abyss. The furthest down we could see the pump was 50 meters from the surface—remarkably far to still see light anywhere in the ocean, courtesy of the life-devoid upper waters of the South Pacific.
That’s a comprehensible depth, 50 meters. It’s about the same as a 15-story building. But five kilometers? My German colleague and I could conceptualize five kilometers horizontally—the same as her bike ride to work, the same as the first ever race I ran. Neither of us could quite grasp what flipping 5 kilometers 90 degrees might mean, as our pump continued on its 3-hour vertical journey to that depth.
The spirit of exploration is embedded within all scientific research. It is a quest to probe and understand the unknown. But oceanographers and astronauts have something more than that—the work they do also involves the physical exploration of spaces that have yet to come under dominion of humanity. The ocean and space have not yet been rendered permanently habitable. No human lives at sea or in space without having to depend on land for survival.
I expected to conclude the cruise with a deeper connection to the ocean. I expected to feel like I had performed an act of exploration by sailing from one land mass to another, and as a result to have gained some fundamental understanding of the ocean’s spatial domain.
Yet a week after I stepped foot from the FS Sonne for good, I am left feeling like the ocean is further from my grasp than ever. Five kilometers depth, and all I did was sail across a tiny fraction of the surface. Sure, I hauled back samples from the deep, and I will certainly learn an incredible amount about it from chemical measurements. But did I explore the deep ocean? Is it possible to explore a place without actually traveling there?
I wonder how astronauts feel when they return to Earth. Just like oceanographers experience only the top of the ocean, astronauts only scratch the surface of an incomprehensibly large volume of space. Does it make them feel like a part of something greater, or does experiencing its massive scale make them feel even smaller?
While the ocean is a vast nexus of life, space is seemingly devoid of it. The ocean certainly holds clues as to how life formed on our planet, and where it may exist on distant moons in our solar system. On Mars, it is the locations of long-dessicated oceans and running water where life is thought to have been possible in the distant past. In habitability, oceans are our pluperfect, Earth is our future perfect, space is our future.
The connection between oceans and space will certainly be a source of excitement for science in the coming years. Ice-covered moons in our solar system have liquid water oceans; surely there are planets and moons orbiting stars other than ours that have them as well. How will we ever understand them if we have only seen such a small portion of the ocean’s volume on Earth?
And so we plunge onward into the indomitable vastness of the oceans, of space. I came away feeling further than ever from the oceans after this cruise. To fix that, I must keep exploring.
By Frankie Pavia
I was talking to a colleague on board today while we were subsampling sediment cores we had taken from the last station. The cores were especially interesting—the entire surface was covered in manganese nodules, some the size of baseballs. Our conversation was interrupted by a mysterious occurrence. In one of the subcores we’d taken, there were manganese nodules sitting at 15 cm and 18 cm deep in the sediment. Conventional wisdom and that infamous beacon of knowledge, scientific consensus, stated that the nodules stayed on top of the sediment and were never buried after formation. There were also bright streaks of white carbonate nearby polluting the otherwise pristine red clay that occupied the rest of the core.
We had been talking about what it would be like to be back on land after a long cruise like this. My colleague has been to sea a few times before, and I was curious as to what she thought would be the most different to us upon returning to dry land. She explained that for her, the biggest change was interacting with strangers. There are only 64 people aboard the boat, and by now I can match a name to every face. I may not speak to them regularly, but I may have seen how they take their coffee, or what kind of cake they prefer in the afternoon, or exchanged a casual “moin” (hello) in the hallway. I haven’t seen a new face in almost four weeks.
I anticipated that being at sea might be lonely. I knew I would miss my friends and family. It has hit especially hard the past two Sundays when my hometown NFL team, the Seahawks, have played playoff games. I usually watch Seahawks games with my best friends in New York and fire texts back and forth to my friends I grew up with the entire time. Those are the times I am most in contact with the people I love. Sitting alone in my cabin aboard the ship, frantically updating Twitter, trying to follow the happenings and score of the game, feels especially isolating.
In a way, being a scientist is an isolating endeavor, no matter what. A friend of mine who writes for a hip-hop website is easy for any music lover to connect with. I talk to him every time a new mix tape drops, debating which tracks are the most fire. Another friend works for a soccer analytics company; he tracks the most popular sport in the world. I talk to him every time I’m watching an entertaining game or have a question about a soccer article I’ve read. But not many of my friends have burning questions about isotope geochemistry. The rare conversations we have had about protactinium have tended to be short and one-sided. I love talking about my research. I love learning about other peoples’ research. On land, I have limited opportunity to have these conversations.
On the ship, these conversations are nonstop. Oceanography is what the scientists on board all have in common—how could we not constantly talk about it? I might not know what someone’s favorite color is, or what town they grew up in. But I could probably give a pretty solid explanation of the questions they’re trying to answer with their research. I’ve detailed the systematics of protactinium and thorium isotopes countless times to other scientists on board and gotten genuinely interested responses, rather than blank stares. I began to understand what my colleague meant about interacting with strangers being the most difficult thing about returning to land. Returning to land will mean returning to the real world. There, my research and much of my identity will get suppressed until I can find my way back to the company of fellow scientists.
But as I had that realization, I was immediately distracted. The manganese nodules had made their first appearance within the deep sediment where they didn’t belong. Reality on land could wait. My colleague and I began to volley back and forth ideas about how they could have been emplaced so deep, and what experiments we could design to test our hypotheses. This is my beautiful reality at sea.
By Frankie Pavia
We’ve just completed our first full station and are remarkably pleased with the results. We collected 8 seawater samples to measure helium isotopes; 20 to measure thorium and protactinium isotopes; 7 in-situ pump filters to measure particulate thorium and protactinium isotopes; 6 manganese oxides cartridges that were attached to the pumps to measure actinium and radium isotopes; and 1 box core of the ocean floor to measure sedimentary thorium and protactinium isotopes. I was going to make this paragraph into the Twelve Days of Christmas song, but 7 pumps-a-pumping doesn’t really roll off the tongue that well.
What all this means is that the first station was a smashing success for us. The only thing that didn’t quite go as planned was the 9-meter-long gravity corer coming up empty. We suspect it may have been due to the corer not being able to penetrate the hard carbonate layer we saw—about 15 centimeters thick in our box core. Nonetheless, we are delighted.
We were especially pleased that our in-situ pumps worked. We arrived on the cruise with the knowledge that the pumps would be there, but figured that somebody would be an expert on how to program them, maintain them and operate them. The pumps are essentially motors hung on a line deep in the water, drawing thousands of liters water through a filter, catching the ocean’s suspended particles.
After a week of poring over the manual, we were finally ready to deploy the pumps. It would take them 2.5 hours to descend to 3,600 meters water depth, 6 hours of pumping, and 2.5 hours for the deepest pump to return. A convenient time to have them pump is overnight. Sleep is hard to come by while on station, so six hours of pumps pumping away at depth is a great excuse to scuttle off to bed.
We were pretty nervous as to whether they would actually work. We had invested a lot of time and energy getting them up and running. What a bummer it’d be if they spent six hours in the deep ocean not doing anything because I had accidentally programmed them to pump at the wrong time, or something. Our test run the previous day had been a bit spotty, too. The flow rate of the pumps had been something like 3 times lower than it should have been.
We woke up at 4 a.m. the next day to wait for the pumps to arrive back on deck, driven by caffeine and nervous energy. Christmas had been two days previous. On Christmas Eve the crew put on a terrific party in the hangar, and the pumps had been decorated with big red ribbons. We were about to find out whether the pumps were a present we actually wanted, or if they were one of those fancy battery-powered toys you get with a list of parts that has three missing and ends up never working.
All the pumps have names. We were able to name the four new pumps after ourselves, while the other four pumps already names. Claudia, Bernhard, Sebastian, Frankie, Laura, Frauke, Jimmy and Hulda. They all seemed to have a little personality too—especially the old ones, Laura, Frauke, Jimmy and Hulda. Parts of Laura were backwards, Hulda’s screws refused to come loose, Jimmy’s pump head had missing pieces.
Claudia was the first to arrive at the surface. Immediately upon getting her out of the water, we put a shower cap over the filter holder to protect the filter from contamination by atmospheric aerosols and any dust floating around the hangar. We pumped the remaining water from the bottom through the filter, removed the filter holder and brought it to the lab. We carefully unscrewed the top, opened it up, and…
The filter was covered in particles! One by one, the pumps came up with filters that were coated by an even distribution of particles. Everything worked perfectly. Even Laura, Hulda and Jimmy, though they were stubborn above water, did everything they were supposed to do once they were submerged.
We plan to measure protactinium and thorium isotopes on the particles to learn about the kinetics of particle movement in the ocean—sinking rates, absorption coefficients for trace metals, and export fluxes. Particles are the vectors that move elements out of the surface ocean, so studying their characteristics will be crucial for understanding how things like carbon and iron are pumped and exported to the deep.
Functional pumps meant that it was a happy Christmas for us. The next full station starts this afternoon. We’ll spend 42 hours sitting in one place, measuring dissolved, particulate and sediment samples. Yesterday we had to change all the batteries on the pumps. Each pump requires 24 D batteries per deployment, and uses them all. So for every cast of 8 pumps, we use 192 D batteries. We’ll send the pumps out tonight and retrieve them at 4 a.m. again tomorrow morning.
We’re hoping these pumps are gifts that keep on giving.
By Frankie Pavia
Six days after we were supposed to have departed, the UltraPac scientists and ship’s crew remain stranded at port aboard the FS Sonne. Containers with the last of our missing science gear are on a truck driving up from San Antonio, Chile, where the port felt comfortable unloading our acids and radioisotopes. The Sonne’s spare parts are being unloaded from a ship across the harbor that I can see from my cabin’s windows. With an abundance of time and a dearth of work, we have begun to devise ways of doing science before we can actually do science at sea.
We first discussed how to optimize our sample depth selections. In the first three stations, the deep waters will be downwind of the East Pacific Rise, one of the fastest spreading mid-ocean ridges in the world. At ridge axes, water that has percolated through the ocean crust and weathered mantle-derived rocks is erupted back out by volcanism and hydrothermal vents. This ‘plume water’ bears a distinct signature of the Earth’s mantle—high in rare noble gases like 3He, biologically critical trace metals like iron and manganese, and small particles that are reactive sites for removing other elements like phosphorous, magnesium, and most importantly (for me!), protactinium and thorium.
When this plume water enters the ocean, it is very hot and less dense than the surrounding waters. It rises until it attains a state of neutral buoyancy—when its density is the same as ambient seawater. Then it simply moves and acts like any other water—in currents and eddies. But since it bears distinct chemical signatures, chemical oceanographers can find easily find it—after they’ve measured something in it.
But we want to know where it is before we sample it. We want to understand the processes going on inside the plume. What kind of particles are there? How fast do they remove trace metals from the ocean? How much iron enters the ocean from submarine volcanism? If we are to answer these questions, we must first be able to sample exactly within the plume waters—which means we must know where they are before we deploy our bottles.
Luckily, past cruises from the World Ocean Circulation Experiment (WOCE) have measured helium isotopes and density in the Pacific before. As a result, we know roughly what density surface is associated with the neutrally-buoyant plume waters. When we sample, we will send down a line with a CTD sensor to measure temperature, salinity, and pressure, from which we can calculate density. That line will have our bottles on it. We can instantaneously calculate the density of the waters we are sampling, find the depth of the density surface we know is associated with plume waters, then tell our bottles to open and sample at that depth. Problem solved!
We also set up an imaging system to take pictures of the particle filters we bring back. At seven depths of each station, we will deploy in-situ pumps that filter thousands of liters of seawater through a filter at a given depth. We then haul the pumps back to the surface, remove the filters, and analyze them.
We would like to photograph the filters before we analyze them so we can visually assess how much material there is on each filter, to confirm the results from our chemistry. To do this accurately, we must photograph every filter from the same angle, with the same lighting, with the same shutter speed. We went to a hardware store in town yesterday and bought some supplies, not knowing if the imagined setup would actually work.
It worked! We turned a lamp with a flexible stand for adjusting light height into a camera holder, decapitating the lamp portion and replacing it with a tripod holding the camera. Then we installed software allowing the camera to be controlled from a phone, so we could take pictures and adjust shutter speed remotely. We bought a clip-on lamp that will be attached to the camera holder for constant lighting (this one used for its true purpose!).
We are finally scheduled to receive our last missing container and depart port late tonight, around 22:00. While the delay has been frustrating, I suppose it hasn’t been all bad. We were scheduled to leave December 17, the day before the new Star Wars movie came out. Six extra days in port meant we were able to go into town to watch it. It was our last little leisure activity on land. Now it’s time for the ocean.
By Frankie Pavia
Still stuck in Antofagasta, the scientists are becomingly increasingly antsy. Every day we are stuck at the port is a day of sampling we won’t be able to do at sea. Every time we want to take a sample from the bottom of the ocean, at around 5,000 meters depth (16,404 feet), it will take us four hours to lower the line, several hours to do sampling (fill bottles, pumps, etc), and four hours to pull it back up. There are several of these casts at each of eight stations. Every hour we have at sea is precious for returning valuable samples.
What am I doing here, anyway? I am an oceanographer and an isotope geochemist. Originally, I only planned to measure naturally occurring radionuclides thorium and protactinium dissolved in seawater and stuck onto ocean particles. But slowly, more scientists found out there was a chance to get seawater from this part of the ocean and asked us to take samples for them.
The South Pacific Gyre is the most oligotrophic (nutrient-poor) region in the ocean. This makes it largely barren of life and matter—the waters are the clearest in the ocean. The sediments accumulate below the water at rates as low as 0.1 millimeter per thousand years. So, 10 centimeters of seafloor are equivalent to one million years of material deposition in the South Pacific.
The scarcity of particles and lack of eukaryotic life are two major reasons the South Pacific is fascinating to a chemical oceanographer.
Surface biology and dust deposition are the two main factors regulating the flux of particles through the ocean interior. Being so far from land and upwind of major dust sources, almost no atmospheric material makes its way to the South Pacific. Since there is no dust, and no eukaryotes, the particles must largely be made up of tiny bacteria, of which there are millions in each milliliter of seawater.
Much of what we are setting out to do is simply the chemical characterization of the region. We are exploring the ocean using chemistry. We can’t see the scarce sinking particles, but trusty old thorium and protactinium can. They are extremely insoluble. Every time they encounter a particle, they stick to it. We exploit this simple characteristic to provide rare accounts of rates in the ocean. Just by measuring protactinium and thorium, we can calculate how fast particles are sinking through the water, how much dust is entering the water column, how fast different elements are being removed from the water at the seafloor, and more. It’s almost incomprehensible that two obscure elements can teach us so much.
These isotopes are the oceanographer’s equivalent to the Hubble telescope.
They help us see where we cannot. We measure thorium and protactinium to tell us input and removal rates. We measure helium isotopes to trace hydrothermal plumes in the deep ocean. We measure radium and actinium isotopes to determine the mixing rates of waters in the deep ocean. None of these processes are discernable by eye, yet all are crucial for understanding the chemical and physical state of the entire ocean.
So we continue to wait to make our measurements and do our science until we can depart. The void is filled by lighthearted scientific arguments, whether or not we could make a jetpack for one of the massive hordes of dead jellyfish floating around the boat. The idea is that you could throw a bit of dry ice underneath the jellyfish, which would then sublimate, expand, and rise out of the water, taking the jellyfish with it.
Ultimately, no one ever tried it. Who wants to do an experiment where you can just see the answer with your own eyes?
By Frankie Pavia
Days -3 to 1, The delay: In the weeks before departing for my first scientific cruise, everyone I knew who had ever been to sea gave me some form of the same advice:
Nothing ever works the way you expect it to work at sea. Four days ago, their words lingered heavily in my head as I groggily walked to board my final connection to Antofagasta, Chile. I wondered to myself, “How can the unexpected happen when I have no idea what to expect in the first place?”
I am typing from my cabin aboard the FS Sonne, a German research vessel scheduled to depart on a scientific sampling cruise between Antofagasta, Chile, and Wellington, New Zealand, crossing the entire South Pacific, between Dec. 17 and Jan. 28. Fellow Lamont-Doherty graduate student Sebastian Vivancos and I will be measuring a variety of chemical tracers in the ocean for our Ph.D. theses on the cruise. The South Pacific is a bit of a unicorn for oceanographers—due to its remoteness, cruises rarely go there, making it hard to get samples. We were presented with the opportunity to collect seawater aboard the FS Sonne as part of the UltraPac program and jumped at the chance.
We arrived three days ago to load the ship, with the help our lab’s research technician and scientific cruise guru, Marty Fleisher. The expectation was that we would stay in a nearby hotel on the 14th and 15th, set up the ship, and on the 16th we would have everything ready to go, stay the night aboard the Sonne, and depart the next morning.
The answer to my first question was answered almost immediately. One of the bags filled with crucial last-minute additions to our sampling equipment was lost in transit by the airline company. After a massive series of calls emails, we had a tracking number, but no idea if the bag would arrive by the morning of the 17th when we would depart. Some of the things we could buy at a local hardware store, but some of it was likely too specialized. I, for one, have never seen a hardware store that sells pizza slicers made of ceramic.
Once again the unexpected struck. Upon meeting with the other scientists on the cruise, we quickly learned that everyone was missing their supplies. Everyone else’s supplies were scheduled to arrive on the 18th—the day after the cruise was scheduled to depart. Then the bombshell: spare parts for the ship were still at least four days away from arriving, and we couldn’t depart until we had them.
The presence of the unexpected was forcing me to realize what my expectations were in the first place. I had been incredibly anxious leading up to the cruise about leaving my life behind for two months while I went to sea with limited connection to the outside world. I was hoping that the solitude of the ocean and the engagement of constant scientific work would buffer that anxiety. The going is slow. There’s not much work to do until the parts get here and we depart. I’m living on the ship, but my journey hasn’t yet begun.
The best-case scenario is that we leave on Sunday. No one has said anything about the worst-case scenario yet, but there have been rumblings of a Christmas in Chile. That leaves somewhere between three more days and seven more days of the uncertain, and the unexpected grasping my life’s puppet strings, postponing the adventure.