Super Station, Super Techs – Part 1

The ultimate goal of GEOTRACES and GP15 is to better understand the world’s oceans. But focus only on the edifice of accumulated scientific knowledge that GP15 hopes to produce, and one risks papering over the efforts of the human beings laying the bricks of data.

hardhat heros
Jensen, Summers and other members of the GP15 team prepare to retrieve the trace metal clean CTD rosette. Telescoping poles are used to attach tag lines. Image: Alex Fox

During GP15’s nearly three-day Super Station at the equator, I followed Laramie Jensen of Texas A&M University and Brent Summers of the University of South Florida, both graduate students in chemical oceanography working as Super Technicians on GP15. “Super Techs,” as they’re called on board, collect and prepare high quality samples for scientists aboard the Roger Revelle and back on land.

Jensen and Summers are integral to the success of GP15, but public recognition of their toil is likely to be relegated to a handful of acknowledgements in the back pages of scientific journals.

The tight schedule of our expedition often forces them to forgo sleep for 24 hours or more, with most of that time spent working together in tight quarters. During GP15 they sleep, eat and work on the same schedule. If I see one of them, I justifiably expect the other to be nearby.

sky bird
A seabird flies over the open expanse of the Pacific Ocean. Image: Alex Fox

The scale of GP15 and the intensity of activity during its stops to collect data can coalesce into something overwhelming. Much of the data produced by this expedition will take a year or more to analyze and interpret. To say each day’s progress is incremental is an understatement.

Contemplating the immensity of GP15’s 39 stations spread across more than 5,000 miles of ocean becomes a liability when, for Jensen and Summers, the task at hand is to split almost 300 liters of seawater into an array of plastic bottles.

What’s a Super Tech?

Each of the major systems GP15 uses to collect samples has one or two Super Techs. These individuals, usually graduate students, look after the instrument itself and help manage the distribution of the samples it produces.

GTC drip
The trace metal clean CTD rosette emerges from the ocean. Tag lines keep it steady as the winch reels it back on deck. Image: Alex Fox

Jensen and Summers are assigned to the trace metal clean CTD rosette, which, through some linguistic sleight of hand, is abbreviated to GTC by the scientists of GP15. What makes the GTC different from other CTD rosette sampling systems is that it specializes in studying trace metals.

Iron is the prototypical trace metal in the oceans. Like all trace metals, iron is scarce, but some of the world’s most prolific marine ecosystems depend on it. Studying an element present only in tiny quantities means samples can easily become contaminated—especially aboard a metal ship.

Just walking around on deck could track in sample ruining metals. With science that is so sensitive to contamination, every precaution is taken to keep samples free of wayward metals. The GTC is made of plastic, titanium, and powder coated aluminum to ensure that the trace metals in its water samples come from the ocean rather than the instrument.

Super Techs collect water on behalf of all researchers looking for samples from the GTC. Centralizing this responsibility streamlines the process of doling out water, cuts down on miscommunication and limits the number of people touching, and potentially contaminating, samples.

What’s a Super Station?

GP15 cruise-track
GP15’s cruise track. Each dot is a different station. Red dots are Super Stations, which receive the most attention from GP15’s instruments. Blue and purple dots are “full” stations, white dots are “demi” stations, the three brown dots are shallow or shelf stations and the green dots are places the Revelle will stop in port. Photo: GEOTRACES

A station is someplace the Roger Revelle stops to take measurements and collect samples of seawater. Each station splits into individual casts of the five sampling systems on board—each one devised to siphon its own breed of data from the Pacific. The transit of those instruments into the deep and back to the surface splinters further into particular depths where bottles seal in water or pumps filter out particles for study.

Super Stations are GP15’s most intensive sampling efforts. They take 52 hours or more to complete. Super Stations receive this extra attention because of some feature that piques oceanographers’ interest. Often, this means the station coincides with something like a hydrothermal vent or a deep sea trench, or that the same location was sampled by a previous expedition—affording an opportunity to compare measurements.

What this extra intrigue amounts to is spending more time at the station to collect more water and more measurements. Here at Super Station 29 the main attraction is the equator.

What’s super about the equator?

At the equator, the trade winds blowing from the east drag water on the ocean surface west. Just above and below the true equator, the rotation of the Earth produces what’s called the Coriolis Effect. This spins the easterly wind, and the surface water it’s pushing, to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

A simple way to think about how the Coriolis Effect works is to try to draw a straight line across a spinning piece of paper. The spinning causes a line that would otherwise be straight to curve one way or the other. The direction of the wind’s curve switches depending on the hemisphere in the same way the arc on the spinning paper would if you flipped the paper over. The difference is that the Earth is a sphere so “the other side of the paper” is geographically quite close by.

The band of green at the equator shows the dramatic increase in chlorophyll, used by phytoplankton in photosynthesis, as a result of upwelling. Phytoplankton are the base of the ocean food chain and their presence supports innumerable other species both large and small. Image: NASA image created by Jesse Allen, Earth Observatory, data from SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE

As the wind pulls surface water away from the equator it is replaced by deeper, nutrient-rich water. This infusion of deep water nutrients is called upwelling and often occurs on the coast. Those nutrients fuel phytoplankton growth which then attracts the whole gamut of ocean life.

This upwelling and the marine life it supports is what makes the equator special for GEOTRACES. “Many of the trace metals and isotopes we are studying on GP15 are tightly coupled with biology,” said Chief Scientist Greg Cutter of Old Dominion University in Norfolk, Virginia. “We are studying the linkage between biology and chemistry in the ocean.”

Prep: November 7


Most of GP15’s science party is catching up on sleep as the Roger Revelle motors south towards the equator. I am on deck with Jensen and Summers preparing for the coming Super Station.

Under the equatorial sun I feel like an ant smoldering beneath a magnifying glass. We make several trips to stow 12 plastic crates in pallet boxes scattered about the ship. Each crate is full of labelled bottles containing the previous station’s seawater samples.

Laramie Jensen (left) and Brent Summers (right) shuffle crates full of seawater samples on deck in preparation for the equatorial Super Station. Image: Alex Fox

This preparation is not optional. If Jensen and Summers kicked back in between stations, the relentless schedule would bury them like an avalanche upon the Revelle’s arrival. If they fall behind it could delay the entire ship’s scientific operations—and with the ship’s operating costs totaling around $60,000 per day, every second is valuable.

We move inside the ship, clanking shut heavy, metal doors behind us. Jensen and Summers remove their shoes and we pile into an improvised clean room we call the bubble—plastic sheeting covers every surface to keep contamination at bay. The room is small and claustrophobic with three people inside.

Summers’ sneakers and Jensen’s clogs just outside the bubble. Image: Alex Fox

Jensen and Summers’ anti-contamination practices make them easy to find, I just look for their abandoned shoes. Summers, 23, has short brown hair and wears black athletic shorts and a turquoise t-shirt covered in pineapples. He is wiry and alert. He laughs easily but carries some kind of tension with him everywhere—perpetually coiled and ready to spring into action. His sense of humor is dry and acerbic, but beneath the stream of baseless insults that keep Jensen and others entertained he is genuine and conscientious.

Jensen, 24, wears black synthetic pants and a black cotton t-shirt. Her brown hair—lighter than Summers’—hangs just past her shoulders. Outwardly, Jensen seems the more relaxed of the pair—sometimes bursting into disconcertingly accurate renditions of bygone pop hits—but she is meticulous. She wears a blue plastic watch on her right wrist that is always timing something—today it has been 17.5 hours since the GTC was last in the water.

B L bubble
Jensen and Summers organize for the coming equatorial Super Station in the bubble. Each of them have one “clean” gloved hand and one “dirty” bare hand as they organize containers that will hold trace metal samples. Image: Alex Fox

They both stand around 5’5 and have oceanic blue eyes—Jensen’s lighter and tropical and Summers’ the darker blue of the North Pacific waters we passed through in late September. It’s not hard to see why they’re sometimes called “the twins.”

The plastic coated bubble appears to contain an unadulterated mess of plastic bags with little open floor space, but the Super Techs flit about easily, stepping in the cracks between crates in their socks.

We finish for the day around 6pm. I tie up some loose ends on the computer and I’m in bed by 11pm. We start work just after 6am tomorrow and from then on we’ll be working or catching our breath for more than 48 hours.

Stay tuned for part 2!

GP15 blog posts written by Alex Fox unless otherwise stated.

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GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

Deep sea mining appears on GP15’s radar

Imagine the year is 2022, a 500-foot deep sea mining ship bobs in the equatorial Pacific Ocean—7.5 degrees North, 152 degrees West. Four years earlier, this was Station 23, where GP15 measured ocean chemistry from the gleaming surface to the sunless abyss.

Mahi mahi hunt the flying fish hiding in the mining vessel’s shadow. A hose as thick as a tree trunk emerges from the ship’s hull and into the azure waters. Shafts of sunlight parallel the hose’s descent until the water turns cold and dark.

deepgreen boat
A deep sea mineral exploration ship surveys the Clarion-Clipperton Zone in the Pacific Ocean. Image: DEEPGREEN

The motors driving the vacuum pumps are deafening. Sediment that took tens of thousands of years to accumulate is sorted by the ton. Like gold rushing 49ers in the riverbeds of California, these deep sea miners are panning an area of the deep Pacific seafloor called the Clarion-Clipperton Zone for potato-sized nuggets called polymetallic nodules.

Polymetallic nodules like this one, the size of a potato, are tens of millions of years old. They grow less than a quarter inch every million years. Image: NOAA DeepCCZ expedition

These metallic spuds take millions of years to form and are rich in the raw materials needed to make cell phones, wind turbines and electric car batteries—manganese, cobalt, nickel, copper, and rare earth elements. Demand for these technologies is on the rise and so are the prices of the metals required to manufacture them. Cobalt for example, is essential for producing the lithium-ion batteries in most cell phones. In March of 2018, the price of cobalt hit a record high of $95,250 per ton, a rise of more than 400 percent since 2016.

The red blocks represent deep sea mining claims inside the Clarion-Clipperton Zone as of 2018. Layered atop the continental US, the area’s 3,100 mile width comes into focus. These claims are all in the exploration phase. Image: Deep Sea Mining Watch

Elsewhere in the Clarion-Clipperton Zone and around the world, the rest of the deep sea mining fleet grinds, sucks and sifts valuable minerals from the ocean floor using technology developed for offshore oil extraction. As the cost of techniques used to drill for deep ocean oil went down and the price of minerals like cobalt went up, deep sea mining went from a hair-brained scheme to a profitable venture.

Harvester DG
DeepGreen’s rendering of a polymetallic nodule harvester. Notably, this illustration doesn’t depict the sediment that would likely be sucked up along with the nodules. Image: DeepGreen

Three miles underwater, the hose connects to something that looks like a cross between a bulldozer and a vacuum that Canada-based deep sea mining company DeepGreen calls a “harvester.” The harvester’s tank treads stamp the millennia-old mud with corrugated symmetry. In these nearly motionless waters, the tracks will remain clear as the day they were made for hundreds of years.

Rattail fishes, large red shrimp, and cusk eels whip their tails and flee across the abyssal plain in advance of the harvester’s billowing plume. The nozzles rip into the seafloor with powerful suction—hoovering nodule-laden slurry back up to the ship.

In 2016 NOAA’s exploration ship Okeanos Explorer discovered this new species of octopus 13,120 feet down near Hawaii. The little octopus was quickly nick-named Casper by its newly adoring public. Similar octopuses lay their eggs on the polymetallic nodules that are the subject of deep sea mining exploration. Image: NOAA Office of Ocean Exploration and Research

A ghostly white octopus, belonging to a species discovered in 2016 and nick-named Casper, protects a clutch of eggs laid directly onto one of the metal nodules. Its pale, limp body, adapted to the crushing water-pressure, disappears into the maw of the harvester along with its brood of 30 eggs. In the near freezing temperatures of the deep sea the eggs might have taken as long as four years to hatch. A sea sponge with a skeleton made of glass splinters as it lifts out of the mud along with the crustaceans and worms taking shelter in its fiber-optic limbs.

Life is slow and precarious 16,000 feet down, built on the predictability of a harsh environment that scarcely changes. This is not a forest that will grow back—the nodules, if they regenerate, will take tens of millions of years. The erasure of this undersea landscape is all but permanent.

Back at the surface, species not yet described by science compress beneath a mound of ancient mud and metal. Since the 1970’s, nine out of every ten species encountered in the Clarion-Clipperton deep sea mining zone had never been seen before. Once the polymetallic nodules are plucked from the morass, the mud will be dumped back into the sea.

An invisible industry starts to take off

Right now in 2018, there are dozens of vessels prospecting in the Clarion-Clipperton Zone—taking cores and mapping mineral resources. “The problem with deep sea mining is that people either think it’s science fiction or it’s not happening in their backyard,” said Douglas McCauley, a marine biologist from the University of California Santa Barbara.

The online tool Deep Sea Mining Watch tracks deep sea mining activity on the high seas. Each orange ship icon represents a vessel currently prospecting for nodules in the Clarion-Clipperton zone. The black line shows GP15’s path. Image: Deep Sea Mining Watch

McCauley helped create an online tool called Deep Sea Mining Watch that uses algorithms and public GPS data to track deep sea mining ships around the world. The resulting map makes the invisible rise of this new industry into something tangible.

The details of mining more than 6,000 feet beneath the waves can vary depending on what is being mined and where, but the preceding vision of the not-so-distant future is eminently possible. “This is like nothing we have done in the oceans before,” said McCauley. “There are question marks around all facets of this activity and yet it seems like we’re going to do it.”

The idea to mine the deep seas has been around for half a century, but a combination of economics and technology finally tipped the scales toward potential profits in the last decade. Beginning in 2001, a United Nations body called the International Seabed Authority has issued mining permits to a mix of 26 countries, state-owned organizations and private corporations. If all the required permits sail through unimpeded, mining could begin as soon as 2022.

CCZ parcels
Solid colored blocks show license areas for deep sea mining exploration in the CCZ. The red line on the left side of the map shows GP15’s path, with circles representing stations where we will stop and sample ocean chemistry. The green squares are Areas of Particular Environmental Interest. These APEI’s will be protected from mining activity in an effort to minimize its environmental impacts. Image: International Seabed Authority

GP15’s path cuts through the western edge of the Clarion-Clipperton Zone, an area of keen interest to deep sea mining outfits. It spans 3,100 miles across the Pacific Ocean, ranges from 12,000 to 18,000 feet deep and is rich in polymetallic nodules. Seventeen of the world’s 26 active contracts for deep sea mining exploration are within the Clarion-Clipperton Zone. These contracts cover 386,000 square miles of seafloor, an area larger than the states of California, Oregon and Washington combined.

Outside the Clarion-Clipperton Zone, hydrothermal vents and undersea mountains may be mined with heavy equipment for grinding and pulverizing their valuable crusts. Minerals that could be harvested from these other two sources include cobalt, manganese, copper, iron, zinc, silver, platinum and gold.

Deep sea mining owes some of its current appeal to environmental and humanitarian issues with existing supply chains for metals like cobalt. More than half of the world’s cobalt comes from the Democratic Republic of Congo, but along with the silvery metal comes a litany of human rights violations, including child labor. This allows deep sea mining companies to position their future product as a more ethical alternative.

The lesser of two evils?

It is inarguable that the deep sea mining workforce is likely to be better treated and better compensated than those working the Congolese mines. Deep sea mining’s second contention—that it is also more environmentally friendly than mining on land—is more tenuous.

“I don’t think there are any easy answers here, but, environmentally speaking, there is no good that comes out of sea bed mining,” said Jeff Drazen, a deep sea biologist from the University of Hawaii. “All the consequences are negative.” Drazen is one of the few scientists to explore the abyssal plain ecosystem of the Clarion-Clipperton Zone with remotely operated vehicles and cameras.

Cnidarian sp
Relicanthus sp.—a new species seen at 13,120 feet in the Clarion-Clipperton Zone that lives on sponge stalks attached to nodules. Image: Craig Smith and Diva Amon, ABYSSLINE Project

“Half of the species we have observed appear to rely on the nodules, even mobile animals seem to prefer them, said Drazen. “The nodules are precisely what make this habitat unique.”

The consequences of mining for polymetallic nodules are extreme at the local scale. A denuded seafloor and miasma of smothering sediment would follow anywhere the harvesters went. Mining at sea could also generate noise pollution harmful to whales and dolphins. But farther reaching impacts are also cause for concern.

“Toxic metals like cadmium and mercury are in these deep sea sediments,” said Drazen. “If you release them into the middle of the water column they could easily get into our ocean food supply.”

The scientists of GP15 also wonder what dumping thousands of years of accumulated mud would do to ocean chemistry. “All of the deep sea mining exploration areas in the Clarion-Clipperton zone overlap with one of the biggest oxygen deficient zones in the ocean,” said GP15 Co-chief Scientist Phoebe Lam of University of California, Santa Cruz. “If these sediments got dumped between 300 and 3000 feet, the low oxygen environment could potentially accelerate the release of heavy metals.”

nodule mining setup
A potential set up for extracting polymetallic nodules from the Clarion-Clipperton Zone. This illustration depicts multiple harvesters operating simultaneously with waste discharge taking place at depth. Image: Agarwal et al., 2012

The severity of this problem will come down to whether most companies pipe their leftover mud all the way back down to the sea floor or if they kiss it goodbye just deep enough to remain out of sight. Dumping in the ocean’s middle depths would provide a more direct line from the mud’s toxic contents to larger fish eaten by people. Drazen would like to see a requirement that ships discharge their leavings back at the sea floor where they came from.

A significant unknown is whether excavating and redepositing thousands of years of nutrients, toxins and stored carbon might impact the ocean’s miraculous ability to absorb carbon dioxide and mitigate climate change. The dynamics involved are complex, but the oceans are interconnected and the effects of tinkering with age old repositories are unlikely to remain isolated.

Setting a baseline

If mining does begin as soon as 2022, monitoring its impacts will be the next challenge. This is where GP15 comes in. “We have the expertise to measure everything the biologists think might be toxic,” said GP15’s Lam. This GEOTRACES expedition will establish a baseline for the area’s ocean chemistry before any mining takes place. If the 17 mining parcels in the Clarion-Clipperton all come to fruition, this baseline can help regulators monitor any future shifts in ocean chemistry.

The scientists of GP15 deploy instruments that will collect water and particles from the currently undisturbed deep sea. Image: Alex Fox

“An important part of characterizing this ecosystem is understanding its chemistry,” said Drazen. “Deep sea mining has the potential to change that chemistry, so having GEOTRACES go through this area is invaluable.”

To their credit, the budding deep sea mining industry seems interested in the opinions of the scientific community. This makes it an even more important time for GP15 to be collecting these data.

“This is a really good time to be involved and to contribute our expertise,” said Lam. “The timing of our cruise is perfect.”

For McCauley and Drazen, the key to ensuring this new industry pays heed to their warnings is increasing the public’s awareness of the endeavor and its risks. “If someone was strip mining in your neighborhood you would notice and care about it,” said McCauley. “But most people in Hawaii or California have no idea this is happening.”

To make good on this rare opportunity to scrutinize an industry’s impact before it takes off, public interests need to take their seat at the table alongside the mining companies currently dominating the conversation.

Otherwise, the logic for mining the deep seas runs like this: The technology of the future, from supercomputers to renewable energy hinges on the ability to store and distribute electricity. The metals needed to power that future are found in the deep sea. Where better to obtain them than far from the existing dirty, corrupt supply chains on land?

“I’m not sure I’ve made up my mind about whether deep sea mining is better than other exploitative mineral extraction methods,” remarked Lam. “It might be a false dichotomy, but it’s hard to choose a deep sea fish over a child in the Democratic Republic of Congo.”

To this end, McCauley and others are engaging international battery alliances about how to improve the existing battery supply chain. The appeal of deep sea mining appears to boil down to being the lesser of two evils. But, before we ransack the deep, it is imperative to interrogate the question of whether two evils are the world’s only choices.

To learn more about other issues impacting the deep sea visit the Deep Ocean Stewardship Initiative.

Note: The author reached out to a DeepGreen employee for comment but did not receive a response in time for publication.  

GP15 blog posts written by Alex Fox unless otherwise stated.

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GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

Images from Leg 1 – Seattle, WA to Hilo, HI – Part 3

The following galleries depict the scientists of GP15 collecting and analyzing samples from the Pacific Ocean. Please refer to the GEOTRACES Glossary for definitions and explanations of the sampling systems and spaces on board the R/V Roger Revelle. Photography by Alex Fox.

The GEOTRACES trace metal clean CTD Rosette.

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The fish.

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The non-trace metal CTD Rosette.

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Lab life.

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GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

Images from Leg 1 – Seattle, WA to Hilo, HI – Part 2

Life and work aboard the Research Vessel Roger Revelle. Photography by Alex Fox.

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The bridge of the Roger Revelle.
The ship’s stores hold all the food for 59 people for more than a month.
on deck
Waves rise up above the bow of the Roger Revelle.
An avian stowaway took up residence in the Revelle’s bow for several days.
dr buck
Clifton Buck of the Skidaway Institute of Oceanography with his equipment for sampling air and rainwater on GP15.
Research technician Keith Shadle of the Scripps Institute of Oceanography on deck.
Science on a 24-hour schedule sometimes requires a costume change to liven things up. Here a unicorn (Colette Kelly) and a dragon (Jennifer Kenyon) prepare to collect samples in the wee hours of the morning.
Naps are essential in the world of GP15, where sleep schedules are secondary to the schedule of the ship’s scientific equipment. Here, Kyle McQuiggan finds a flat spot on deck.
The optimal temperature for the Roger Revelle’s computers is on the chilly side. The computer lab stayed quite cool regardless of the conditions outside.
the argo life chose me
Left to right: Paul Henderson of Woods Hole Oceanographic Institute, Phoebe Lam of University of California, Santa Cruz and Colette Kelly of Stanford University carry an ARGO float. Close to 4000 of these autonomous floats record oceanographic data throughout the world’s oceans.
letting go of argo
Colette Kelly of Stanford University sends an ARGO float on its way. Close to 4000 of these autonomous floats record oceanographic data throughout the world’s oceans.
this tire
This tire softens any impacts while reeling in delicate scientific equipment.
not a cloud not a boat
The tip of Hawaii, the first land GP15 had encountered in more than 30 days at sea.
joseph can see the future
The landward rail attracts a crowd.
yang crushing it per usual
The science party for leg 1 of GP15 assembles for a group photo just minutes from reaching port in Hilo.
All 37 members of GP15’s science party stand together before arriving in Hilo, Hawaii.
everybody context
All 37 members of GP15’s science party stand together before arriving in Hilo, Hawaii.
port of hilo
The port of Hilo emerges from the fog of more than 30 days on the Pacific.

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GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.


Images from Leg 1 – Seattle, WA to Hilo, HI – Part 1

The sky and the sea seem endless in the open ocean. All photography by Alex Fox.

An albatross swoops above the Pacific.
fishing gear
A wayward piece of fishing gear floats along in an expanse of blue.
Clouds getting some color from the sunset.
gabi and sean looking out
There are no shortage of vistas while at sea.
Whitecaps as far as the eye can sea from the bridge of the R/V Roger Revelle.
The R/V Roger Revelle’s winch arm lets out cable as the Pacific undulates beneath.
soft ocean
The ocean takes on a bewildering variety of textures and colors over the course of a month.
Sea and sky.
The sun sets as the R/V Roger Revelle makes its way to our next station.
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The surface of the Pacific taking on a metallic coating as the scientists of GP15 search for iron, cobalt and manganese (to name a few).
silky trash
A piece of plastic pollution, perhaps a milk crate, floats by.
sunset rays
Sunset or sunrise?
throwing bows
A partial rainbow at sea.
The engines of the R/V Roger Revelle can churn the ocean in some delightful ways.
Velella Bucket
A fellow sailor. This is a velella, a small jellyfish that travels the surface of the ocean using its transparent sail to catch the wind.
Velella Murline1
Captain David Murline holds a velella up to the horizon before releasing it back to the sea.

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GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.


Not that kind of cruise—a GEOTRACES glossary

As the Research Vessel Roger Revelle sails the Pacific Ocean on its mission to study ocean chemistry, certain normal sounding words and phrases take on altered meanings. What follows is a list of 10 common words and phrases one might hear during GP15 along with their definitions. They are not presented in alphabetical order.


These lines represent the many planned and completed GEOTRACES expeditions. Oceanographers typically call these scientific voyages cruises. Photo: GEOTRACES

In these blog posts, GP15 is mostly called an expedition, but when oceanographers talk to their colleagues GP15 is a cruise. Our outreach materials skip the word “cruise” because it makes it sound like we’re taking a vacation to Tahiti. GP15 is many things, but a vacation is not one of them.


GP15 cruise-track
This is GP15’s cruise track. Each dot is a different station. Red dots are Super Stations, blue and purple dots are “full” stations, white dots are “demi” stations, the three brown dots are shallow or shelf stations and the green dots are places the Revelle will stop in port. Photo: GEOTRACES

Each dot along this map of GP15’s path is a station—someplace we will stop to take measurements and collect samples of seawater. The different colors indicate how many depths we will study at each station. Ocean chemistry varies dramatically with depth, so the chemical oceanographers of GP15 are always looking to collect water from a carefully selected set of depths. The most intensive stations are called Super Stations, and take roughly 56 hours to complete.


things happening
Moments before the start of a cast, scientific equipment is airborne above the Pacific Ocean. Next, it will be lowered thousands of feet down by a cable to study ocean chemistry. Photo: Alex Fox

Whenever one of the instruments on board the Research Vessel Roger Revelle goes into the water, it’s called a cast—short for hydrocast. Like fishers casting their bait into the ocean with a rod a reel, the oceanographers of GP15 attach their devices to cables to study the ocean from top to bottom. Some casts are quick, others take more than five hours to complete.

For most of GP15, the bottom is more than 16,000 feet down, and a majority of our stations call for samples from near the seafloor. A round trip to 3,000 feet takes about an hour, and that’s more or less without stopping. Some instruments need to be lowered deeper than 16,000 feet and remain there for hours collecting data.

“The board of lies”

The whiteboard outside the main lab of the Roger Revelle shows the day’s schedule, but each day’s challenges result in frequent amendments and alterations. Photo: Alex Fox

Outside the main laboratory on the R/V Roger Revelle there is a whiteboard. This whiteboard is the subject of intense interest from the scientists of GP15 because it is where one of the chief scientists writes down the day’s schedule. The schedule tells everyone when they will be working and when they can sleep, eat or hang out.

However, there is a reason these schedules are written in dry erase marker and not etched in stone. They are subject to change. These changes can occur at any time, sometimes while the relevant parties are sleeping. The board strives to accurately represent the schedule, but its supreme authority combined with its unpredictability makes a certain amount of friction inevitable.

“CTD Rosette”

gtc drip
The trace metal CTD Rosette emerges from the ocean. Two tag lines are used to keep the CTD steady as it is reeled in. Photo: Alex Fox

CTD stands for conductivity, temperature, and depth. The measurement of electrical conductivity is used to determine the water’s salinity. Rosette refers to the ring of bottles attached to the cylindrical metal frame. The technology that measures conductivity, temperature and depth is nested in the center of the instrument’s metal frame, beneath the rows of bottles. Despite being composed of two separate systems it is often just called “the CTD.”

This key instrument is lowered into the ocean to collect seawater samples from various depths. On each cast the CTD’s rosette of bottles remain open on the way down, allowing water to pass through them freely. On the way back up, if the scientists of GP15 want a sample of seawater from a certain depth they can remotely trigger one of the bottles to snap shut—sealing the seawater inside.

odf ctd hang
GP15’s other CTD on its way down with its Rosette of bottles. Photo: Alex Fox

GP15 has two CTD Rosettes on board. One made specifically for studying trace metals without contaminating its samples, and the other is used to study less contamination prone elements of ocean chemistry.


artsy niskins
A row of bottles lines the wall of the ship’s hangar. Photo: Alex Fox

When oceanographers talk about popping bottles at sea they’re not planning a champagne-soaked celebration. The bottles of oceanography are devices that are used to bring samples of seawater back up to the surface. Their defining feature is the ability to be triggered from the surface to collect water from a particular depth. They can be used individually or they can be arranged in a ring as in a CTD Rosette.

everybody samples
After spending hours underwater, the CTD returns from the ocean. Once it’s inside the hangar, the scientists of GP15 flock to it to collect seawater for their research. Photo: Alex Fox

When arranged in a ring around a CTD the bottles can be “fired” remotely from the ship’s computer lab, but in the case of a single bottle the old school method is to send what’s called a “messenger.” The messenger is a puck with a hole in it that snaps onto the cable the bottle is attached to, slides down the cable and triggers the bottle’s spring loaded lid like a mousetrap. Depending on the system being used, GP15’s bottles may hold 10, 20 or 30 liters of water.


another pump
One of the in situ pumps of GP15 is raised out of the water after pumping seawater through its filters thousands of feet down. Photo: Alex Fox

Short for in situ pump, the pumps of GP15 use motors to push massive volumes of seawater through a set of filters designed to catch ocean particles for study. The in situ part of their full name means they do their pumping in the environment they’re studying, and in this case that means a specific depth at one of GP15’s stations in the Pacific Ocean.

Built around a metal frame, a pump’s main feature is a metal cylinder that can withstand the intense pressure 16,000 feet underwater. Inside the pressure case are a fleet of D-batteries that power the motor. Plastic tubes lead from the pump motor to the filters at the top of each pump that catch the particles the scientists are after. Each pump typically pumps for four hours at its chosen depth.


now that's a torpedo
GP15 scientists wrangle the fish’s torpedo. The fish’s plastic tube is attached to a rope that carries the load as it swims beneath the surface. Photo: Alex Fox

The fish is not some unfortunate sea creature that the scientists of GP15 pressed into oceanographic service. The fish swims alongside the Roger Revelle while it is in transit from one station to the next. At its most basic level, the fish is a tube that pumps seawater from the ocean’s surface back to the Revelle’s laboratory. It earns its piscine moniker by way of a torpedo that swims the tube below the surface and away from the moving ship.

once and future fish
The fish swims alongside the R/V Roger Revelle at a depth of around 15 feet. Photo: Alex Fox

The purpose of the fish is to deliver water samples from the ocean’s surface for trace metal analysis. The fish swims while the Revelle is underway to ensure the water it pumps is fresh and uncontaminated by the Revelle’s metal hull.


This van is responsible for processing samples from the trace metal CTD Rosette. These samples can easily become contaminated, which is why the van is a designated “clean room.” Photo: Alex Fox

On GP15, if someone invites you inside their van there’s no reason to get nervous. On GEOTRACES expeditions a van is a shipping container with a laboratory inside it. After a trip across the country to reach Seattle, WA where GP15 began, the crew of the Roger Revelle bolted the vans to the ship’s deck. GP15 has four vans, each specialized for a different type of oceanographic research. The vans provide crucial lab space to the 37 scientists of GP15 and also provide a little extra shade on deck.

“The bubble”

bubble pumps
Co-chief Scientist Phoebe Lam of the University of California Santa Cruz and her graduate students Vinicius Amaral and Yang Xiang work together inside the sterile confines of the bubble. Photo: Alex Fox

The bubble is a capsule of cleanliness for studying samples prone to contamination from the ship environment. Its walls are made out of sheets of plastic and a group of large air filters fill the bubble with clean air like a balloon. The bubble would pop, but, instead of doors that seal shut, it has flaps. The flaps allow clean air to slowly escape and, in the process, this slight outward pressure keeps contaminants from blowing in.

GP15 blog posts written by Alex Fox unless otherwise stated.

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GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

The north Pacific’s “shadow zone” traps the oldest water in the ocean

In the middle of the northern Pacific Ocean, the scientists of GP15 encountered a shadowy relic of the marine realm: the oldest seawater on the planet. This blob of ancient water last touched the surface during the peak of the Maya civilization in modern day Mexico and Central America—roughly 1,200 years ago. Shrouded in darkness, this blob is loaded with nutrients like nitrogen and phosphorus, but it’s also acidic and oxygen-depleted compared to most of the ocean.

Once this water lost contact with the atmosphere, oceanographers started counting its birthdays. “So much happens when water is at the surface—gases in the air are exchanged and nutrients like nitrogen get sucked up by plankton,” said Co-chief Scientist Phoebe Lam of the University of California, Santa Cruz.

For oceanographers, this water is a trove of ocean history. “These waters are the sum of all these processes in the ocean,” said Co-chief Scientist Karen Casciotti of Stanford University in Palo Alto, California. “I want to know what happens to this water over such a long period of time.”

The CTD Rosette, just before spending hours lowering to more than 16,000 feet underwater. As the winch reels it back in, scientists on board the Research Vessel Roger Revelle trigger its bottles to snap shut at certain depths to collect seawater for analysis. This is one of the chief instruments by which they will study the oldest water in the oceans. Photo: Alex Fox

This water sits around 6,000 feet down and isn’t even close to being the world’s deepest. That title is currently held by a 36,070-foot deep chasm called Challenger Deep that lurks within the already unfathomable Mariana Trench in the western Pacific. Yet, even the waters of Challenger Deep, more than 7,000 feet deeper than Mount Everest is tall, return to the surface faster than GP15’s aged quarry.

A long, dark trip

Stale but well traveled, this water’s thousand year journey began on the surface of the north Atlantic. After years drifting north and baking in the subtropical sun, evaporation turned the water’s upper layer briny. Near Greenland, things cooled off. Becoming saltier and colder increased the water’s density compared to its neighbors, causing it to sink.

conveyor belt
The dark blue line traces the “conveyor belt” of deep water around the world. GP15’s station 12 intersects this ribbon of old, deep water in the north Pacific Ocean at 37 degrees North, 152 degrees West. Image: Sarmiento, Jorge and Nicolas Gruber, “Ocean Biogeochemical Dynamics.” Princeton University Press, 2006.

This dense combination of extra cold and salt sank the water to around 6,000 feet where it climbed aboard what oceanographers call, “the conveyor belt.” The conveyor belt is a one-way procession of deep water that travels around the globe. The explanation for every twist and turn of the belt is still the subject of active research, but density is generally accepted as a driving force.

The belt ferries its most stagnant passengers to a dead end, called the “shadow zone,” in the north Pacific. This is where GP15 encountered these dank waters.

The shadow zone is a clump of water almost totally cut off from the surface, an amorphous purgatory of nearly motionless water. Above and below the shadow zone are waters of contrasting densities that lock it in place. Its only escape is being pushed out as “new” thousand-year-old water seeps in.

An elementary history

“This old water carries a chemical history of all the ecosystems it flows under,” said Casciotti. “It’s called the conveyor belt because all these nutrient-rich particles fall onto it, get broken down and their nutrients get carried to the north Pacific.”

But being cut off from the sun and the atmosphere has chemical consequences. The oldest seawater’s oxygen content is low—microbes used it to decompose organic matter like whale poop. All these microbes chowing down in turn release carbon dioxide, which forms carbonic acid and makes the water more acidic. But it’s not all bad news for living things, because the longer this water is cut off from the surface, the longer it has to accumulate nutrients. Near the surface, those nutrients would get snapped up, but deeper down when microbes run short on oxygen and food nutrients like nitrogen and phosphate build up.

The conveyor belt chugs along beneath a multiplicity of ocean environments, collecting chemical clues from each that the scientists of GP15 can use to understand the marine environment. Photos: Alex Fox

Flash forward a thousand years, and the result is a deep sea stew of nutrients. This larder of rotten ocean helps supply the booming sea life of the north Pacific. Off the coasts of places like Seattle and San Francisco these nutrient-laden waters are swept up from the deep by wind in what’s known as coastal up-welling. At the surface, those nutrients fuel huge blooms of phytoplankton that form the base of an ocean buffet.

What about climate change?

The western U.S. seafood industry is built on this old, deep water, but climate change is turning this already acidic brew caustic. The more carbon dioxide humans pump into the atmosphere the more carbon dioxide the oceans absorb, and this means more carbonic acid. Along the west coast, ocean acidification is forcing longstanding oyster farms to treat their seawater to keep the baby shellfish from dissolving in the saltwater acid bath.

Mel Seattle
Downtown Seattle in the rear view of the Research Vessel Roger Revelle at the start of GP15 on September 18. Photo: Melissa Miller

So far, climate change hasn’t exerted much influence on the size, speed or direction of the conveyor belt, but it’s not outside the realm of possibility. “The rate of the conveyor belt has changed in the past,” said Lam. “During the last ice age it’s thought to have become more sluggish.”

In what might generously be described as a Hollywood blockbuster, the 2004 movie The Day After Tomorrow imagined what might happen if climate change caused this huge ocean process to grind to a halt. In a span of days, a tidal wave hits New York City, super storms the size of continents appear and much of the Northern Hemisphere descends into an ice age.

“The real life version of The Day After Tomorrow scenario is that rising global temperatures melt glaciers in northern Canada and Greenland, sending lots of fresh water into the system,” said Lam. “Because this water isn’t salty it doesn’t sink, which in theory could shut down the conveyor belt’s north Atlantic source of deep water and make things pretty chilly in Europe.”

Crucially, this sort of shift would play out across years or decades, rather than days as it does in the film. Oceanographers have been looking for changes in ocean circulation, but only hints have emerged thus far, according to Lam.

Checking their work

A litany of ocean processes accumulate in this ancient, deep water. Dissecting its chemistry offers an opportunity to fine tune oceanography’s understanding of these cycles. Do current models correctly predict what shows up at the end of the line? What about rare elements that are also necessary for life like iron? “This water helps you check your work,” said Lam. “We’ve got ideas of how various trace elements and isotopes behave at this scale based on limited data, but now we’re putting it to the test.”

CTD party
Whether it’s 3 a.m. or 3 p.m., the return of the CTD Rosette turns the hanger into a hive of scientific activity—each researcher vying for their share of the seawater contained in its 36 bottles. Photo: Alex Fox

This antique slurry lets GP15’s scientists reach beyond their GPS coordinates to capture the life and times of the chemical ocean.

“Where iron and other trace elements are getting on and getting off the conveyor belt isn’t well understood,” said Casciotti. “There is a lot we still don’t know. Bringing this water back to the lab is exciting.”

GP15 blog posts written by Alex Fox unless otherwise stated.

Follow GEOTRACES GP15 on



GEOTRACES GP15 is supported by the National Science Foundation. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.