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Research Highlights

News & Insights

Wave Glider provides gateway to remote exploration

November 10, 2020

WHOI geochemist Chris German pairs an autonomous surface vehicle (ASV) called a Wave Glider with other vehicles to expand research here and on other Ocean Worlds

Mining ancient dust from the ocean’s loneliest spot

September 24, 2020

Researchers investigate dust from the ocean’s farthest point from land to reconstruct the climactic history of the Southern Hemisphere, and understand how micronutrients have influenced biological productivity in this oceanic desert.

Working from Home: Mallory Ringham

July 2, 2020

WHOI-MIT joint program student outfits her basement to do vital work on a marine carbon sensor

oil spill

A dangerous leak of diesel fuel in the Arctic

June 18, 2020
plastics by the numbers

The many lifetimes of plastics

June 15, 2020

Infographics strive to give us a sense of how long plastic goods will last in the environment. But is this information reliable? The findings of a new study from WHOI may surprise you.

toxins story

Are natural toxins in fish harmful?

May 28, 2020

Marine life has been naturally producing toxic chemicals well before chemical companies were manufacturing PCBs. But are these naturally-produced compounds as harmful as man-made environmental pollutants, and do those pose a human health threat?

Working from Home: Matt Long

May 7, 2020

A marine chemist spends his time at home tinkering on a high-tech buoy in the basement, proving that being homebound doesn’t mean you can’t think big.

Our Radioactive Ocean: Ken Buesseler

April 30, 2020

Ken Buesseler joins the hosts of Future Hindsight Podcast to talk about the safety of the Pacific Ocean, the natural occurrence of radioactivity in our environment, and a citizen scientist project for oceanic testing.

Why Sunlight Matters for Marine Oil Spills

April 30, 2020

A decade of research since the Deepwater Horizon disaster has revealed how sunlight—its importance long understated in oil spill science—substantially alters petroleum floating at the sea surface.


Finding medical answers in the ocean

March 19, 2020

The test being used to diagnose the novel coronavirus—and other pandemics like AIDS and SARS—was developed with the help of an enzyme isolated from a microbe found in marine hydrothermal vents as well as freshwater hot springs.

News Releases

New geochemical tool reveals origin of Earth’s nitrogen

April 15, 2020
Volcanic gas emissions in Northern Iceland. The research team collected gas samples here that were analyzed as part of this study. (Photo by Peter Barry, © Woods Hole Oceanographic Institution) Volcanic gas emissions in Northern Iceland. The research team collected gas samples here that were analyzed as part of this study. (Photo by Peter Barry, © Woods Hole Oceanographic Institution)

Novel analysis method may also be useful for monitoring volcanic activity

Researchers at Woods Hole Oceanographic Institution (WHOI), the University of California Los Angeles (UCLA) and their colleagues used a new geochemical tool to shed light on the origin of nitrogen and other volatile elements on Earth, which may also prove useful as a way to monitor the activity of volcanoes. Their findings were published April 16, 2020, in the journal Nature.

Nitrogen is the most abundant gas in the atmosphere, and is the primary component of the air we breathe. Nitrogen is also found in rocks, including those tucked deep within the planet’s interior. Until now, it was difficult to distinguish between nitrogen sources coming from air and those coming from inside the Earth’s mantle when measuring gases from volcanoes.

“We found that air contamination was masking the pristine ‘source signature’ of many volcanic gas samples,” says WHOI geochemist Peter Barry, a coauthor of the study.

Without that distinction, scientists weren’t able to answer basic questions like: Is nitrogen left over from Earth’s formation or was it delivered to the planet later on? How is nitrogen from the atmosphere related to nitrogen coming out of volcanoes?

Barry and lead author Jabrane Labidi of UCLA, now a researcher at Institut de Physique du Globe de Paris, worked in partnership with international geochemists to analyze volcanic gas samples from around the globe—including gases from Iceland and Yellowstone National Park—using a new method of analyzing “clumped” nitrogen isotopes. This method provided a unique way to identify molecules of nitrogen that come from air, which allowed the researchers to see the true gas compositions deep within Earth’s mantle. This ultimately revealed evidence that nitrogen in the mantle has most likely been there since our planet initially formed.

“Once air contamination is accounted for, we gained new and valuable insights into the origin of nitrogen and the evolution of our planet,” Barry says.

While this new method helps scientists understand the origins of volatile elements on Earth, it may also prove useful as a way of monitoring the activity of volcanoes. This is because the composition of gases bellowing from volcanic centers change prior to eruptions. It could be that the mix of mantle and air nitrogen could one day be used as a signal of eruptions.

This study was supported by the Deep Carbon Observatory and the Alfred P. Sloan Foundation. The research team also included colleagues David Bekaert and Mark Kurz from WHOI, scientists from several other U.S.-based universities, and from France, Canada, Italy, the United Kingdom and Iceland.

A new geochemical analysis method helps scientists understand the origins of volatile elements on Earth, and may also prove useful as a way of monitoring the activity of volcanoes, such as this one, Mount Etna on the east coast of Sicily, Italy. (Video by Peter Barry, © Woods Hole Oceanographic Institution)

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit

Key Takeaways

  • Nitrogen is the most abundant gas in Earth’s atmosphere, but it’s origin and how much is in Earth’s interior was previously unknown.
  • A new method of nitrogen analysis of volcanic gases from around the world revealed more accurate measurements of volatile elements in Earth’s interior.
  • This new method could be useful in monitoring the activity of volcanoes.
  • Nitrogen in Earth’s mantle has most likely been there from the beginning of our planet.
Healy, Polarstern

A rapidly changing Arctic

April 8, 2020

Shelf sediments, freshwater runoff from rivers brings more carbon, nutrients to North Pole

A new study by researchers at Woods Hole Oceanographic Institution (WHOI) and their international colleagues found that freshwater runoff from rivers and continental shelf sediments are bringing significant quantities of carbon and trace elements into parts of the Arctic Ocean via the Transpolar Drift—a major surface current that moves water from Siberia across the North Pole to the North Atlantic Ocean.

In 2015, oceanographers conducting research in the Arctic Ocean as part of the International GEOTRACES program found much higher concentrations of trace elements in surface waters near the North Pole than in regions on either side of the current. Their results published this week in the Journal of Geophysical Research-Oceans.

“Many important trace elements that enter the ocean from rivers and shelf sediments are quickly removed from the water column,” explains WHOI marine chemist Matthew Charette, lead author of the study. “But in the Arctic they are bound with abundant organic matter from rivers, which allows the mixture to be transported into the central Arctic, over 1,000 kilometers from their source.”

Trace elements, like iron, form essential building blocks for ocean life. As the Arctic warms and larger swaths of the ocean become ice-free for longer periods of time, marine algae are becoming more productive. A greater abundance of trace elements coming from rivers and shelf sediments can lead to increases in nutrients reaching the central Arctic Ocean, further fueling algal production.

Key Takeaways

  • Trace elements may increase with future Arctic melt releasing dissolved organic matter from permafrost thaw.
  • Nutrient levels and productivity may increase in the Arctic, but loss of ice cover will continue to worsen overall warming as more heat is absorbed from the atmosphere.

Transpolar Drift as a Source of Riverine and Shelf-derived Trace Elements to the Central Arctic Ocean  (Journal of Geophysical Research: Oceans, 2020)

Expedition Map

Click image to enlarge. Map of the USCGC Healy route during 2015 expedition in the Arctic Ocean as part of the International GEOTRACES program. (Illustration by Natalie Renier, © Woods Hole Oceanographic Institution)

“It’s difficult to say exactly what changes this might bring,” says Charette. “but we do know that the structure of marine ecosystems is set by nutrient availability.”

Nutrients fuel the growth of phytoplankton, a microscopic algae that forms the base of the marine food web. Generally speaking, more phytoplankton brings more zooplankton—small fish and crustaceans, which can then be eaten by top ocean predators like seals and whales.

Higher concentrations of trace elements and nutrients previously locked up in frozen soils (permafrost) are expected to increase as more river runoff reaches the Arctic, which is warming at a much faster rate than most anywhere else on Earth.  While an increase in nutrients may boost Arctic marine productivity, Charette cautions that the continued loss of sea ice will further exacerbate climate warming, which will impact ecosystems more broadly.

“The Arctic plays an important role in regulating Earth’s climate, with the ice cover reflecting sunlight back to space, helping to mitigate rising global temperatures due to greenhouse gas emissions,” he adds. “Once the ice is gone, the Arctic Ocean will absorb more heat from the atmosphere, which will only make our climate predicament worse.”

A polar bear sighting off the U.S. Coast Guard Cutter Healy during the 2015 Arctic GEOTRACES expedition. The Arctic has experienced the highest degree of warming on the planet, causing sea ice to thin and recede. The region’s iconic polar bears rely on sea ice to hunt, travel and mate. (Video courtesy of Bill Schmoker PolarTrek teacher 2015 GEOTRACES Arctic expedition)

Funding for Arctic GEOTRACES was provided by the U.S. National Science Foundation, Swedish Research Council Formas, French Agence Nationale de la Recherche and LabexMER, Netherlands Organization for Scientific Research, and Independent Research Fund Denmark. The Arctic GEOTRACES expeditions were supported by the captains and crew of the USCGC Healy and the R/V Polarstern.

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit

Buesseler sediment trap

The ocean’s ‘biological pump’ captures more carbon than expected

April 6, 2020

Scientists have long known that the ocean plays an essential role in capturing carbon from the atmosphere, but a new study shows that the efficiency of the ocean’s “biological carbon pump” has been drastically underestimated. (Video by Elise Hugus, UnderCurrent Productions, © Woods Hole Oceanographic Institution)

Every spring in the Northern Hemisphere, the ocean surface erupts in a massive bloom of phytoplankton. Like plants, these single-celled floating organisms use photosynthesis to turn light into energy, consuming carbon dioxide and releasing oxygen in the process. When phytoplankton die or are eaten by zooplankton, the carbon-rich fragments sinks deeper into the ocean, where it is, in turn, eaten by other creatures or buried in sediments. This process is key to the “biological carbon pump,” an important part of the global carbon cycle.

Scientists have long known that the ocean plays an essential role in capturing carbon from the atmosphere, but a new study from Woods Hole Oceanographic Institution (WHOI) shows that the efficiency of the ocean’s “biological carbon pump” has been drastically underestimated, with implications for future climate assessments.

In a paper published April 6 in Proceedings of the National Academy of Sciences, WHOI geochemist Ken Buesseler and colleagues demonstrated that the depth of the sunlit area where photosynthesis occurs varies significantly throughout the ocean. This matters because the phytoplankton’s ability to take up carbon depends on amount of sunlight that’s able to penetrate the ocean’s upper layer. By taking account of the depth of the euphotic, or sunlit zone, the authors found that about twice as much carbon sinks into the ocean per year than previously estimated.

The paper relies on previous studies of the carbon pump, including the authors’ own. “If you look at the same data in a new way, you get a very different view of the ocean’s role in processing carbon, hence its role in regulating climate,” says Buesseler.

“Using the new metrics, we will be able to refine the models to not just tell us how the ocean looks today, but how it will look in the future,” he adds. “Is the amount of carbon sinking in the ocean going up or down? That number affects the climate of the world we live in.”

In the paper, Buesseler and his coauthors call on their fellow oceanographers to consider their data in context of  the actual boundary of the euphotic zone.

“If we’re going to call something a euphotic zone, we need to define that,” he says. “So we’re insisting on a more formal definition so that we can compare sites.”

Rather than taking measurements at fixed depths, the authors used chlorophyll sensors —indicating the presence of phytoplankton— to rapidly assess the depth of the sunlit region. They also suggest using the signature from a naturally-occuring thorium isotope to estimate the rate at which carbon particles are sinking.

Buesseler is a principal investigator with WHOI’s Ocean Twilight Zone project, which focuses on the little-understood but vastly important mid-ocean region. In a commentary published in Nature on March 31, Buesseler and colleagues call on the international marine research community to intensify their studies of the twilight zone during the upcoming United Nations Decade of the Ocean (2021-2030). Increased understanding of the twilight zone ecosystem and its role in regulating climate, the authors say, will lead to global policy to protect the area from exploitation.

Coauthors of the paper include: Phillip Boyd of University of Tasmania, Australia; Erin Black of Dalhousie University, Nova Scotia, and Lamont Doherty Earth Observatory, New York; and David Siegel, University of California, Santa Barbara.

This work was funded by: WHOI’s Ocean Twilight Zone project; NASA as part of the EXport Processes in the global Ocean from RemoTe Sensing (EXPORTS) program; the Ocean Frontier Institute at Dalhousie University; and the Australian Research Council.

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit

Key Takeaways

  • Using photosynthesis, phytoplankton floating on the ocean’s surface absorb carbon dioxide from the atmosphere. The depth of this sunlit layer affects the efficiency of the ocean’s “biological carbon pump” or ability to take up carbon.
  • By measuring the depth of the ocean’s sunlit surface area, or “euphotic zone”, scientists found that the “biological carbon pump” is twice as efficient as previously estimated.
  • Using this method could lead to more accurate climate models, such as those used by the Intergovernmental Panel on Climate Change, to set global climate policy.
  • More study of the mid-ocean “twilight zone” will lead to better understanding of the biological carbon pump’s role in regulating climate and the productivity of fisheries.
Buesseler sediment trap Marine chemist Ken Buesseler (right) deploys a sediment trap from the research vessel Roger Revelle during a 2018 expedition in the Gulf of Alaska. Buesseler’s research focuses on how carbon moves through the ocean. Buesseler and co-authors of a new study found that the ocean’s biological carbon pump may be twice as efficient as previously estimated, with implications for future climate assessments. (Photo by Alyson Santoro, © Woods Hole Oceanographic Institution)

Report reveals ‘unseen’ human benefits from ocean twilight zone

January 22, 2020


Exclusive report

Value Beyond View: Illuminating the human benefits of the ocean twilight zone

Download now – it’s free!

Did you know that there’s a natural carbon sink—even bigger than the Amazon rainforest—that helps regulate Earth’s climate by sucking up to six billion tons of carbon from the air each year?

A new report from researchers at Woods Hole Oceanographic Institution (WHOI) reveals for the first time the unseen—and somewhat surprising—benefits that people receive from the ocean’s twilight zone. Also known as the “mesopelagic,” this is the ocean layer just beyond the sunlit surface.  

The ocean twilight zone is a mysterious place filled with alien-looking creatures. The nightly, massive migration of animals from the zone to the surface waters to find food helps to cycle carbon through the ocean’s depths, down into the deep ocean and even to the seabed, where it can remain sequestered indefinitely. 

“We knew that the ocean’s twilight zone played an important role in climate, but we are uncertain about  how much carbon it is sequestering, or trapping, annually,” says Porter Hoagland, a WHOI marine policy analyst and lead author of the report. “This massive migration of tiny creatures is happening all over the world, helping to remove an enormous amount of carbon from the atmosphere.” 

Exactly how much carbon is difficult to pinpoint because the ocean twilight zone is challenging to get to and is understudied. The WHOI Ocean Twilight Zone project, which launched in April 2018, is focused on changing that with the development of new technologies. 

It’s estimated that two to six billion metric tons of carbon are sequestered through the ocean’s twilight zone annually. By comparison, the world’s largest rain forest sucks in only about 544 million metric tons of carbon a year—five percent of the world’s annual 10 billion metric tons of carbon emissions. 


Using a range of prices for carbon, reflecting future damages expected as a consequence of a changing climate, this “regulating” service has an estimated value of $300 to $900 billion annually, Hoagland notes. Without the ocean’s ability to sequester carbon, atmospheric carbon dioxide levels could be as much as 200 parts per million higher than they are today (about 415 ppm), which would result in a temperature increase of about six degrees Celsius or 10.8 degrees Fahrenheit. 

In addition to its role in the carbon cycle, the twilight zone likely harbors more fish biomass than the rest of the ocean combined, and it is home to the most abundant vertebrate species on the planet— the bristlemouth. While twilight zone fish are unlikely to ever end up on peoples’ dinner plates because of their small size and strange appearance, they do provide meals for larger, economically important fish, like tuna and swordfish, and for other top predators, including sharks, whales, seals, penguins, and seabirds.

The twilight zone’s biological abundance makes it an attractive target for commercial fishing operations. Ocean twilight zone animals could be harvested to produce fish meal to support the rapidly growing aquaculture industry and to provide fish oils for nutraceutical markets. Because the twilight zone is situated largely in unregulated international waters, there is concern that its potential resources could be subject to unsustainable exploitation. 

The research team hopes that the report will be useful for decision makers, such as the United Nations delegates who will meet this spring in New York to continue developing a new international agreement governing the conservation and sustainable management of marine life on the high seas, in areas beyond the coastal waters managed by individual member States.

“We need to think carefully about what we stand to gain or lose from future actions that could affect the animals of the twilight zone and their valuable ecosystem services,” says Hoagland. “Increasing scientific understanding is essential if we are going to move toward a goal of the sustainable use of the resources.”

Read Frequently Asked Questions about the ocean twilight zone, or download the report.

This research is part of the Woods Hole Oceanographic Institution’s Ocean Twilight Zone Project, funded as part of The Audacious Project housed at TED.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit

Key Takeaways

  • The ocean’s twilight zone provides benefits to humans that occur largely out of sight.
  • Ocean twilight zone creatures remove two to six billion metric tons of carbon annually, comprising a regulating service worth $300 to $900 billion each year.
  • Without the nightly animal migrations that help shuttle carbon to the deep ocean, atmospheric carbon dioxide levels could be as much as one-third more than they are today, which translates to an average temperature increase of about six degrees Celsius or 10.8 degrees Fahrenheit.
  • Commercial interests are considering the harvest of twilight zone organisms as a source of proteins and lipids for expanding aquaculture and nutraceutical operations, which are expected to grow by 37 percent from 2016 to 2030.
  • The loss of the carbon sequestration service as a consequence of a changing climate or the overfishing of twilight zone animals could amount to significant mitigation and adaptation costs (estimated in the hundreds of billions to trillions of dollars) by the end of the century.

Got questions? Read our FAQs.

How microbes reflect the health of coral reefs

December 19, 2019

Microorganisms play important roles in the health and protection of coral reefs, yet exploring these connections can be difficult due to the lack of unspoiled reef systems throughout the global ocean. A collaborative study led by scientists at the Woods Hole Oceanographic Institution (WHOI) and the Centro de Investigaciones Marinas – Universidad de La Habana (CIM-UH) compared seawater from 25 reefs in Cuba and the U.S. Florida Keys varying in human impact and protection, and found that those with higher microbial diversity and lower concentrations of nutrients and organic carbon—primarily caused by human activities—were markedly healthier.

“Human impacts such as overfishing and pollution lead to changes in reef structure,” says WHOI graduate student Laura Weber, lead author of the paper. A healthy reef provides home to a diverse group of marine animals, including herbivores that in turn help control algal growth. “Removal of algae grazers such as herbivorous fish and sea urchins leads to increases in macroalgae, which then leads to increased organic carbon, contributing to the degradation of coral reefs,” Weber adds.

Key Takeaways:

  • Offshore and highly-protected reefs are healthier than nearshore reefs with less protection from human impacts.
  • Reefs with lower nutrient runoff and carbon from industrial activities are markedly healthier.
  • More species of microbes were found on healthier Cuban reefs than impacted Floridian reefs.

Researchers sampled seawater from each site and measured nutrients as well as a suite of parameters that offer insights into the microbial community. They found a notable difference between the heavily protected offshore reefs in Cuba and the more impacted nearshore ones in the Florida Keys.

Jardines de la Reina (Gardens of the Queen), the largest protected area in the Caribbean, is a complex ecosystem of small islands, mangrove forests, and coral reefs located about 50 miles off the southern coast of Cuba. These highly-protected offshore reefs provide habitat and feeding grounds for large numbers of fish, including top predators like sharks and groupers. Here, researchers found low concentrations of nutrients, and a high abundance of Prochlorococcus—a photosynthetic bacterium that thrives in low nutrient waters.

“Cuba does not have large-scale industrialized agriculture or extensive development along most of its coastline,” says Patricia González-Díaz, Director of CIM-UH and co-author of the study. “So there is not a lot of nutrient run-off and sedimentation flowing on to the reefs.” Additionally, the reefs of Jardines de la Reina may be further buffered from impacts by the mangroves and seagrass meadows that lie between the island of Cuba and the reef system of Jardines de la Reina.

Coral reefs Florida Keys

Nearshore reefs in the heavily-impacted Florida Keys show unhealthier corals and less marine life. This mountainous star coral (Orbicella faveolata) from offshore Summerland Key shows patches of dead coral, now overgrown with algae. (Photo by Amy Apprill, ©Woods Hole Oceanographic Institution)

Conversely, seawater from the more accessible reefs of Los Canarreos, Cuba—which are more impacted by humans through subsistence and illegal fishing, tourism, and the diving industry—and the nearshore reefs in the Florida Keys both contained higher organic carbon and nitrogen concentrations.

The study demonstrates that protected and healthier offshore Cuban reefs have lower nutrient and carbon levels, and microbial communities that are more diverse with abundant photosynthetic microbes compared to the more impacted, nearshore reefs of Florida. This work suggests that the offshore nature and highly protected status of reefs in Jardines de la Reina have played a role in keeping these reefs healthy by being far from or minimizing human impacts. These findings may aid resource managers in decision making to protect and restore Caribbean coral reefs in the face of habitat and climate-based change.

The study was published in the journal Environmental Microbiology on December 13. Co-authors of the paper include colleagues from CIM-UH, Universidad Nacional Autónoma de México, Phillip and Patricia Frost Museum of Science, Mote Marine Laboratory, and the University of California, Santa Barbara. For more information, visit Amy Apprill’s lab.

Funding for this work was provided by OceanX and the National Science Foundation.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit

WHOI-engineered DISCO allows scientists to measure highly reactive superoxide on coral reefs

December 12, 2019

Researchers at Woods Hole Oceanographic Institution (WHOI) successfully conceived and tested a portable device, DISCO, that performed the first in situ measurements of a highly reactive type of oxygen, known as superoxide, which may play an integral role in the health of coral reefs. Their findings were published as an early view article on Oct. 29 in the journal of Environmental Science and Technology.

Superoxide is a reactive chemical that is a byproduct within all respiring and photosynthesizing organisms. This unstable form of oxygen, or reactive oxygen species (ROS), is prone to stealing or giving electrons. As a consequence, superoxide has been known to catalyze chemical reactions that can lead to cancer and other diseases—one of the many reasons today’s diets stress incorporating antioxidant-rich foods, such as blueberries, nuts or dark chocolate. However, in many organisms, including corals, the nature of superoxide may be more complicated.

“It used to be that [superoxide] was only considered toxic,” says WHOI marine chemist Colleen Hansel, a coauthor of the study. “But we know now that it’s used for a lot of beneficial processes. In fungi, plants and even animals, superoxide is important for an organism’s immune response [for example]. That [logic] hasn’t really transferred over into marine life yet.”

Hansel and her team investigated the chemical’s interaction with symbiotic microorganisms that inhabit coral reefs. Preliminary evidence suggests that while corals may not be immune to superoxide’s toxic effects when it reaches high concentrations inside their cells, they may also be employing the chemical outside their cells for beneifical reasons, such as a defense against marine infections––some of which may be spurred on by warmer ocean temperatures.

“Superoxide to organisms reflects like a kind of Goldilocks effect,” says Kalina Grabb, the study’s lead author and WHOI-MIT Joint Program student in Hansel’s lab.  “You don’t want too much because it can lead to oxidative stress, but you don’t want too little because it’s essential for physiological functions.”

Until recently, the ephemeral nature of superoxide has made it incredibly difficult to sample in the marine environment– the chemical only lasts mere minutes in seawater. This traditionally left no time to transfer water samples to a lab for adequate analysis. At the same time, other boat-borne systems were cumbersome to operate and could only be used in very select environments.

To overcome these limitations, WHOI engineer Jason Kapit and WHOI scientist Scott Wankel worked closely with Hansel and her lab to develop the world’s first portable DIver-operated Submersible Chemiluminescent SensOr, or DISCO. With it, they were able to sample superoxide concentrations in real time during a 2017 research trip to Cuba’s pristine reef system, Jardines de la Reina.

The boxy handheld device comprises a water-sealed battery and a tablet screen that scuba divers can operate at depth. Inside, fluidic pumps uptake the invisible chemical as corals produce it. DISCO then adds a chemical to the mixture that reacts with superoxide to create measurable light, read by an onboard sensor. Armed with these tools, DISCO detected notable differences in superoxide levels between species of corals in its first field test.

“Now, we want to be able to get at the why,” adds Hansel. “Why are they purposely making superoxide and is this helping the coral or is it related to stress in some way?”

A DISCO in the Ocean

WHOI scientist Colleen Hansel scuba-dives to corals in Cuba’s Gardens of the Queen reefs with the first model of DISCO, which stands for DIver-operated Submersible Chemiluminescent sensOr. (Photo by Ashlee Lillis, © Woods Hole Oceanographic Institution)

Since its inception, DISCO has been reengineered to become even more portable and lightweight. In 2018, Hansel, Wankel and Kapit collaborated on another iteration of the device, this time at roughly half the size and weight of its predecessor. The team has also adapted DISCO into a deep-sea version known as SOLARIS to accompany WHOI’s human-occupied submersible, ALVIN. In October 2019, they were able to use SOLARIS to detect superoxide produced by corals at 1,300 meters deep (~4,200 feet) along the Davison Seamount off the coast of central California.

“We are already talking about what we can do next with this technology,” says Hansel. “How can we build new sensors that incorporate other reactive oxygen species to fully understand their role in organismal health and ocean chemistry? I don’t see an end in sight.”

Also collaborating on the paper were Scott Wankel, Jason Kapit, Kevin Manganini and Amy Apprill of Woods Hole Oceanographic Institution, and Maickel Armenteros from Universidad de La Habana.

The research was funded by Schmidt Marine Technology Partners (G-1801-57385; to CMH), the National Science Foundation Graduate Research Fellowship Program (to KCG), and the Dalio Foundation’s Ocean Initiative (now ‘OceanX’) (to AA). The research was conducted in the Jardines de la Reina, Cuba, in accordance with the requirements of the Republic of Cuba, conducted under permits NV2370 and NV2568 issued by the Ministerio de Relaciones Exteriores (MINREX). This research was also conducted in accordance with a memorandum of understanding between the National Center of Protected Areas (CNAP) of the Ministry of Science, Technology and Environment (CITMA) in Cuba and the Woods Hole Oceanographic Institution in the USA.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit



Laura Weber collects a syringe sample from seawater surrounding an Orbicella faveolata coral colony in Jardines de la Reina, Cuba.

New Study Finds Distinct Microbes Living Next to Corals

May 21, 2019

Symbiotic algae living inside corals provide those animals with their vibrant color, as well as many of the nutrients they need to survive. That algae, and other microbes within the bodies of corals, have been extensively studied—yet until now, researchers have largely ignored the microbial communities just outside of the coral colonies. A new study from scientists at the Woods Hole Oceanographic Institution (WHOI) has begun to describe and catalogue microbes that live just a few centimeters from the surface of corals, laying the groundwork for future studies. The researchers’ work published May 21 in the journal Limnology and Oceanography.

“Microbes are everywhere on reefs. There’s roughly a million of them in a single milliliter, which is about 20 drops, of seawater. But we don’t yet have a good sense of the microbial population that exists right next to corals,” says Laura Weber, lead author of the study and a PhD student in the joint WHOI-MIT program. “There’s some evidence from previous studies that corals may be surrounded by unique microbial cells, but many questions are still unanswered. Do these cells differ with coral species or reef site? How might they function?” she says.

To begin to chip away at those questions, Weber and her colleagues focused on sampling the seawater surrounding Caribbean corals across multiple reefs. Weber thinks that microbes immediately next to the corals could play a role in breaking down waste products from the colonies, introducing new nutrients and potentially letting symbiotic algae or pathogens into the corals themselves.

Along with her PhD advisor, Amy Apprill, Weber traveled to a protected coral reef system called the “Jardines de la Reina,” located amid a string of remote islands near the southern coast of Cuba. Once there, Weber teamed with local Cuban scientists Patricia Gonzalez-Díaz and Maickel Armenteros to dive on the reefs and collect dozens of small samples from the water near five different species of coral.

“The Cuban reefs provided a perfect opportunity for this study. Because they’re so remote, there’s limited impact from human activities,” says Apprill, a coral reef ecologist at WHOI and senior author on the paper. A majority of the reef system was established as a marine protected area by the Cuban government in 1996, so fishing is prohibited and diving tourism is restricted. “The Cuban scientists we collaborated with are also doing research that complements our own. They have extensive knowledge of their marine environment, and provided access to research permits, which was a clear advantage when planning sites for cruises,” Apprill adds.

Once the samples were back in the US, Weber analyzed the genetic material of the microbes inside them to figure out which species were present. She found that different types of coral did indeed have different microbial communities living near them. ”We started finding cool species-specific trends,” Weber says. “I didn’t think we would see any differences at all—but it turned out that in some areas, the bacterium Endozoicomonas, which lives symbiotically with corals, was actually enriched in the seawater closer to corals compared to the surrounding  reef water. That means the region adjacent to corals could be important for attracting symbionts to a coral’s surface, or it could represent a region where corals shed their symbionts.”

In addition to understanding which microbes are living next to corals, Weber and Apprill also looked at the microorganisms’ potential ecological functions. They found that the seawater microbes contained genes that let them interact with the coral surface, suggesting that there may be important interactions between seawater microorganisms and the coral surface.

“Scientists have been working for a while now to understand the role of microorganisms in reef environments and within coral colonies. But now we have evidence that demonstrates a possible relationship between seawater microbes and coral symbionts. That gives us some clues to how they find and infect coral colonies, and how they might impact the health of the corals. It’s very exciting,” Weber says.

This project was funded by the Dalio Explore Fund, which supports scientific research at WHOI. The fund is part of Dalio Philanthropies’ larger commitment to ocean exploration and discovery, including the new OceanX initiative.

“We are thrilled to support WHOI’s scientific research efforts through the Dalio Explore Fund,” said Vincent Pieribone, Vice Chairman, OceanX. “The findings from this mission will help reveal the secret lives of coral, how their microbiome – similar to ours – supports good health, and how, when they are at an imbalance, corals, like humans, can become sick.”

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit

Biofilm in a natural seep in Costa Rica. Credit: Peter Barry.

Microbes May Act as Gatekeepers of Earth’s Deep Carbon

April 24, 2019

Two years ago an international team of scientists visited Costa Rica’s subduction zone, where the ocean floor sinks beneath the continent and volcanoes tower above the surface. They wanted to find out if microbes can affect the cycle of carbon moving from Earth’s surface into the deep interior. According to their new study in Nature, the answer is affirmatively—yes they can.

This groundbreaking study, published in Nature, shows that microbes consume and – crucially – help trap a small amount of sinking carbon in this zone. This finding has important implications for understanding Earth’s fundamental processes and for revealing how nature can potentially help mitigate climate change.

At a subduction zone there is communication between Earth’s surface and interior. Two plates collide and the denser plate sinks, transporting material from the surface into Earth’s interior. Showing that the microbes at the near-surface are playing a fundamental role in how carbon and other elements are being locked up into the crust provides a profound new understanding of Earth processes and helps researchers model how Earth’s interior may develop over time.

“What we’ve shown in this study is that in areas that are critically important for putting chemicals back down into the planet – these big subduction zones – life is sequestering carbon,” said Chris Ballentine, Head of the Department of Earth Sciences at the University of Oxford and a co-author of the paper. “On geological timescales life might be controlling the chemicals at the surface and storing elements like carbon in the crust.”

This is the first evidence that subterranean life plays a role in removing carbon from subduction zones. It has been well established that microbes are capable of taking carbon dissolved in water and converting it into a mineral within the rocks. The research showed that this happens on the large scale across a subduction zone. It is a natural CO2 sequestration process which can control the availability of carbon on Earth’s surface.

“We found that a substantial amount of carbon is being trapped in non-volcanic areas instead of escaping through volcanoes or sinking into Earth’s interior,” said Peter Barry, WHOI marine chemist and lead author of the paper. Barry carried out the research while at the Department of Earth Sciences, Oxford University.

“Until this point scientists had assumed that life plays little to no role in whether this oceanic carbon is transported all the way into the mantle, but we found that life and chemical processes work together to be the gatekeepers of carbon delivery to the mantle.”

During the 12-day expedition, the 25-person group of multi-disciplinary scientists collected water samples from thermal springs throughout Costa Rica. Scientists have long predicted that these thermal waters spit out ancient carbon molecules, subducted millions of years before. By comparing the relative amounts of two different kinds of carbon – called isotopes – the scientists showed that the predictions were true and that previously unrecognized processes were at work in the crust above the subduction zone, acting to trap large amounts of carbon.

Following their analyses, the scientists estimated that about 94 percent of that carbon transforms into calcite minerals and microbial biomass.

The researchers now plan to investigate other subduction zones to see if this trend is widespread. If these biological and geochemical processes occur worldwide, they would translate to 19 percent less carbon entering the deep mantle than previously estimated.

The research is part of the Deep Carbon Observatory’s Biology Meets Subduction project. The interdisciplinary team included 25 researchers from six nations belonging to each of the Deep Carbon Observatory (DCO) Science Communities: Deep Life, Extreme Chemistry and Physics, Reservoirs and Fluxes, and Deep Energy.

Watch this video for a glimpse of the 2017 field campaign, including the final descent into Póas Volcano’s active crater. Credit: Deep Carbon Observatory/CoLab Productions

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit

Sunlight Reduces Effectiveness of Dispersants Used in Oil Spills

Sunlight Reduces Effectiveness of Dispersants Used in Oil Spills

April 25, 2018

Two new studies have shown that sunlight transforms oil on the ocean surface more significantly and quickly than previously thought. The phenomenon considerably limits the effectiveness of chemical dispersants, which are sprayed during oil spills to break up floating oil and reduce the amount of oil that reaches coastlines.

A research team led by Woods Hole Oceanographic Institution (WHOI) found that sunlight chemically alters crude oil floating on the sea surface within hours or days. In a follow-up study the team reported that sunlight changes oil into different compounds that dispersants cannot easily break up. The results of these two studies could affect how responders decide when, where, and how to use dispersants.

The related studies were published on February 20, 2018, in the Journal Environmental Science & Technology and today (April 25, 2018) in the journal Environmental Science & Technology Letters.

“It has been thought that sunlight has a negligible impact on the effectiveness of dispersants,” said Collin Ward, a scientist at WHOI and lead author of both studies. “Our findings show that sunlight is a primary factor controlling how well dispersants perform. And because photochemical changes happen fast, they limit the window of opportunity to apply dispersants effectively.”

Dispersants contain detergents, not unlike those people use to wash dishes, which help break oil into small droplets that can become diluted in the ocean, and/or are eaten by microbes before the oil can be swept to sensitive coastlines. But to do their work, the detergents (also known as surfactants) first need to mix with both the oil and water—and oil and water, famously, don’t mix.

To overcome this barrier, dispersants contain an organic solvent that helps the oil, detergents, and water to mix. Only once this key step occurs can the surfactants do their work to break oil into droplets. But sunlight hinders this key step, the new studies show.

Before dispersants can even be applied, light energy from the sun is already breaking chemical bonds in oil compounds—splitting off atoms or chemical chains and creating openings for oxygen to attach. This photo-oxidation process (also known as photochemical “weathering”) is similar to the process that causes paint on your car or colors on your clothes to fade if they are left out in the sun for too long.

To date, tests to determine dispersants’ effectiveness used only “fresh” oil that hadn’t been altered by sunlight. In the new studies, the researchers conducted extensive lab tests exposing oil to sunlight. They showed that sunlight rapidly transforms oil into residues that are only partially soluble in a dispersant’s solvent. That limits the ability of detergents to mix with the photo-oxidized oil and break the oil into droplets.

The finding suggests that responders should factor in sunlight when determining the “window of opportunity” to use dispersants effectively. That window will be far shorter than previously thought on sunny days than it would on cloudy days.

“This study challenges the paradigm that photochemical weathering has a negligible impact on the effectiveness of aerial dispersants applied in response to oil spills,” Ward said. “Sunlight rapidly alters oil into compounds that dispersants can’t easily break up into droplets. So photochemical weathering is a critical factor that should be considered to optimize decisions on when to use dispersants.”

In laboratory experiments in the 1970s, scientists showed that light alters the chemistry of oil, but the findings could not be applied to large-scale oil spills in the ocean. This was largely because in most spills, the oil quickly flowed away from the scene before it could be sampled. The long-duration flow from the 2010 Deepwater Horizon disaster provided a unique opportunity: Because oil floated on the sea surface for 102 days, it gave officials a chance to collect oil while it was floating on the sunlit sea surface.

The WHOI scientists obtained and tested samples of Deepwater Horizon oil that was skimmed from the surface almost immediately after it surfaced and was exposed to sunlight. They found that the longer the oil floated on the sunlit sea surface, the more the oil was photo-oxidized. They estimated that half of the spilled oil had been altered within days.

The next step was to test how the photo-oxidized oil would respond to dispersants. The scientists tested fresh unaltered Deepwater Horizon oil that was collected directly from the broken riser pipe on the seafloor. They meticulously controlled laboratory conditions to prevent temperature changes, evaporation, light infiltration, and other factors, and they exposed the oil to increasing durations of light. Cassia Armstrong, a guest student from Trinity College, played a key role in conducting these tests and is an author of the paper.

The WHOI scientists also closely collaborated with Robyn Conmy, one of the U.S. Environmental Protection Agency’s leading experts on developing new technologies for responding to oil spills. To conduct tests on the effectiveness of dispersants, the EPA uses a specific method and custom-designed glassware, which Conmy loaned to the WHOI scientists for their experiments.

Results of the experiments showed that light rapidly photo-oxidized the fresh oil, changing it into compounds that reduced the effectiveness of dispersants by at least 30 percent in a few days.

Next the scientists teamed with Deborah French McCay, an internationally recognized oil spill modeler at RPS ASA, a science and technology consulting firm in Rhode Island. They simulated conditions that might have occurred during the Deepwater Horizon spill, including a range of wind speeds and sunlight levels. Then they superimposed the actual 412 flight lines of planes that sprayed dispersants during the crisis.

The results showed that under average wind and sunlight conditions, the majority of dispersant applications would not have achieved even the minimum effectiveness levels designated by the EPA, because they targeted photochemically weathered oil. Even under the best-case scenarios for aerial dispersant spraying—cloudy weather (which would limit photochemical weathering) and high-wind conditions (which would transport oil farther from the spill area before sunlight transformed it)—dozens of aerial dispersant applications still would not have achieved EPA-designated effectiveness levels.

“We assembled a team that combined the expertise of academia, government, and industry,” explained Christopher Reddy, marine chemist at WHOI. “In future oil spill crises, the community needs the same kind of cooperation and collaboration to efficiently make the wisest decisions on how to respond most effectively.”

“This study shows how important it is to do the most basic research on chemical reactions that take place in the environment,” said Henrietta Edmonds, a program director in the National Science Foundation’s Division of Ocean Sciences, which funded the research. “The results help us learn how to effectively respond to oil spills.”

The Gulf of Mexico Research Initiative and the DEEP-C (Deep Sea to Coast Connectivity in the Eastern Gulf of Mexico) consortium also funded this research.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit



Radioactivity Lingers from 1946-1958 Nuclear Bomb Tests

Radioactivity Lingers from 1946-1958 Nuclear Bomb Tests

October 30, 2017

Scientists have found lingering radioactivity in the lagoons of remote Marshall Island atolls in the Pacific Ocean where the United States conducted 66 nuclear weapons tests in the 1940s and 1950s.

Radioactivity levels  at Bikini and Enewetak Atolls were extensively studied in the decades after the testing ended, but there has been relatively little work conducted there recently. A team of scientists from Woods Hole Oceanographic Institution (WHOI) reported that levels of radioactive cesium and plutonium have decreased since the 1970s, but these elements continue to be released into the Pacific Ocean from seafloor sediments and lagoon waters.

The levels of plutonium are 100 or more times higher in lagoon waters compared to the surrounding Pacific Ocean and about two times higher for a radioactive form of cesium. Despite these enrichments, they do not exceed U.S. and international water quality standards set to protect human health, the scientists reported Oct. 30, 2017, in the journal Science of the Total Environment.

To determine the source of these radionuclides in lagoon waters, the WHOI scientists measured the amounts and flow of radioactive material entering the ocean from groundwater seeping from the islands. They found that groundwater was a relatively low source of radioactivity.

In particular, they found that radioactive groundwater was not leaking much from beneath one suspected potential source: the Runit Dome on the island of Runit—a massive 350-foot-wide concrete lid that covers 111,000 cubic yards of radioactive soil and debris that were bulldozed into a bomb crater and sealed over. It was constructed in the late 1970s by the U.S. government to contain contaminated waste from the nuclear tests. The bottom of the Runit Dome is not lined and below sea level, so scientists and others have been concerned that tidal action could move water through the buried radioactive material and bring it out to sea.

“The foundations of these island atolls are ancient coral reefs that have the porosity of Swiss cheese, so groundwater and any mobilized radioactive elements can percolate through them quite easily,” said WHOI geochemist Matt Charette. Though that does not seem to be happening now, the scientists advise that the Runit Dome area should be continuously monitored as sea level rises and the dome deteriorates.

Using isotopes of plutonium that act like a fingerprint to pinpoint sources, the WHOI scientists found that the seafloor sediments around Runit Island seem to be contributing about half of the plutonium to the lagoon.  “Additional studies examining how radioactive plutonium moves through the environment would help elucidate why this small area is such a large source of radioactivity,” Buesseler said.

The WHOI scientists who conducted the study and wrote the report included Ken Buesseler, Matthew Charette, Steven Pike, Paul Henderson, and Lauren Kipp. They sailed to the islands aboard the research vessel Alucia on an expedition funded by the Dalio Explore Fund.

The team collected sediments from the lagoon with poster tube-sized collectors that were inserted by divers into the seafloor’s sediments, filled with mud, capped. Back in WHOI laboratories, the cores were sliced into layers and analyzed to reveal a buried record of local fallout from the nuclear tests. The scientists also collected and analyzed samples of lagoon waters .

On the islands, they collected groundwater samples from cisterns, wells, beaches, and other sites. They analyzed these samples for the levels of radioactive cesium and plutonium from weapons tests. For the first time on these islands, the scientists also measured isotopes of radium, a naturally occurring radioactive “tracer” that give scientists key information to determine how much and how fast groundwater flows from land into the ocean.

The WHOI research team also compared the radioactive contamination at the Marshall Islands to the contamination found today near Fukushima in Japan in the aftermath of the Dai-ichi Nuclear Power Plant disaster.  “In contrast to Fukushima, where cesium is the most abundant radionuclide of concern, in these atolls, the focus should be on plutonium, given its significantly high levels,” said WHOI radiochemist Ken Buesseler.

The U.S. conducted 66 nuclear weapons tests between 1946 and 1958 at Bikini and Enewetak Atolls, each a ring of low-lying reef islands that surrounds a larger lagoon. Bikini has 26 islands; Enewetak had 42 islands, but three were bombed out of existence. They became known as the western part of the “U.S. Pacific Proving Grounds.”

Bikini and Enewetak are among 29 atolls that make up the Republic of the Marshall Islands, located in the equatorial Pacific, about 2,500 miles west of Hawaii. The collective land area of the thousands of small islands is equivalent to the area of Washington, D.C. but they are spread across an ocean area that exceeds the size of Alaska.

The work holds particular significance to the atolls’ indigenous populations which were evacuated before the tests and thus far have only been allowed to return to one small island in the Enewtak Atoll.

This research was funded by the Dalio Foundation and the Dalio Explore Fund.

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean’s role in the changing global environment. For more information, please visit

Oceanus Magazine

Earthquake aftermath

福島第一と海: 災害対応の10年間を語る

April 1, 2021



English Version

On the high seas

Observers join Orpheus cruise thanks to the Neil Armstrong Fund

By Hannah Piecuch















Reactor Explosion


2011年6月に行われた最初の国際調査航海では、福島第一原発付近沿岸から482キロメートル以上沖合までの放射性核種の拡散を追跡した。過去10年以上にわたり、科学者、技術者、一般市民が、発電所近海からカナダ及びアメリカ合衆国の西海岸の広範囲において、海水、堆積物、海洋生物のサンプルを採取してきた。(撮影:ケン・コステル、©ウッズホール海洋研究所) 2011年6月に行われた最初の国際調査航海では、福島第一原発付近沿岸から482キロメートル以上沖合までの放射性核種の拡散を追跡した。過去10年以上にわたり、科学者、技術者、一般市民が、発電所近海からカナダ及びアメリカ合衆国の西海岸の広範囲において、海水、堆積物、海洋生物のサンプルを採取してきた。(撮影:ケン・コステル、©ウッズホール海洋研究所)







Food Chain








福島第一原発の事故後、誤った情報が拡散し、科学者や政府関係者の情報へ対する世間の不信感が高まった。一般的に誤って伝わったもののひとつの例として、福島第一原発でメルトダウンした直後の放射性物質の広がりを示した地図と思われたものは、実際には地震後に太平洋を横断する津波モデルの分布図であった。 (米国海洋大気庁太平洋海洋環境研究所より転載) 福島第一原発の事故後、誤った情報が拡散し、科学者や政府関係者の情報へ対する世間の不信感が高まった。一般的に誤って伝わったもののひとつの例として、福島第一原発でメルトダウンした直後の放射性物質の広がりを示した地図と思われたものは、実際には地震後に太平洋を横断する津波モデルの分布図であった。 (米国海洋大気庁太平洋海洋環境研究所より転載)









2011年3月11日に始まった終わりない惨劇の遺物、それは福島第一原子力発電所の敷地内に設置された千基以上の汚染された処理水を保存する貯蔵タンクである。日本政府はこれらのタンク内の汚染水を徐々に海洋に放出する予定である。厳密にはその処理水の中にどの放射性同位体がどの程度含まれているのか、明確にされていない。(撮影:ケン・ベッセラー、©ウッズホール海洋研究所) 2011年3月11日に始まった終わりない惨劇の遺物、それは福島第一原子力発電所の敷地内に設置された千基以上の汚染された処理水を保存する貯蔵タンクである。日本政府はこれらのタンク内の汚染水を徐々に海洋に放出する予定である。厳密にはその処理水の中にどの放射性同位体がどの程度含まれているのか、明確にされていない。(撮影:ケン・ベッセラー、©ウッズホール海洋研究所)










=(ローラ・カスタニヨン) biology Coastal Ecosystems Ocean Life

Fukushima and the Ocean: A decade of disaster response

April 1, 2021

Fukushima Dai-ichi and the Ocean:

A decade of disaster response

By Laura Castañon

On the high seas

Observers join Orpheus cruise thanks to the Neil Armstrong Fund

By Hannah Piecuch

On March 11, 2011, a magnitude 9 earthquake 80 miles east of the Japanese city of Sendai generated a towering tsunami that slammed into the coastline and critically damaged the Fukushima Dai-ichi nuclear power plant. Nearly 16,000 people died and the releases of radioactive water from the plant continue today. (Photo by Ken Kostel, © Woods Hole Oceanographic Institution)

On March 11, 2011, 80 miles east of the Japanese city of Sendai, the seafloor heaved. The tectonic plate that holds Japan, which had been slowly compressed by the Pacific plate diving underneath it, suddenly slipped and sprang back. In a matter of moments, parts of the ocean floor were shoved as much as half a football field horizontally and 30 feet upwards.

Japan experiences hundreds of earthquakes every year, but the Great Tohoku Earthquake was the most powerful the country had ever recorded. The 9.0-magnitude quake lasted as long as six minutes and shifted the main island eight feet to the east.

Tsunami waves, generated as the seafloor thrust upwards, hit the closest parts of the Japanese coastline less than half an hour later. Entire towns were destroyed by the three-story wall of water and nearly 16,000 people were killed.

The Fukushima Dai-ichi nuclear power plant had also been damaged. In the following days, explosions rocked the facility and more than 150,000 people were forced to evacuate the surrounding area to avoid potential radioactive fallout. Even more radioactivity was washed into the ocean or deposited there from the atmosphere.

“Fukushima Dai-ichi was an unprecedented event for the ocean, in terms of the amount of radioactivity going in to the ocean from a disaster of this nature,” said Ken Buesseler, a senior scientist at the Woods Hole Oceanographic Institution. “It seems very important to look back and take stock of where we’re at.”

A decade after Japan’s triple disaster, Buesseler joined researchers around the world for a remote discussion of the events at Fukushima, what they’ve learned over the past decade, and how the situation continues to evolve.

Inside the power plant

The Fukushima Dai-ichi nuclear plant had systems in place to cope with an earthquake. When the violent shaking damaged utility lines and cut off the plant and its six reactors from the power grid, the three active reactors shut down automatically. But shutting off a nuclear reactor isn’t as simple as turning off the lights.

“Even if the fission reaction stops, the radioactive material continues to generate heat,” said Jota Kanda, a professor at Tokyo University of Marine Science and Technology who has led several research expeditions off the coast of Fukushima. “You have to keep cooling by water for quite a long period.”

The facility switched over to its backup generators to continue pumping the water needed to cool the fuel rods. Then the tsunami hit.

The nuclear plant was constructed on a cliff which had been excavated down to 30 feet above the ocean. The maximum expected height of a tsunami in that area was around 20 feet, Kanda said. But the tsunami waves that hit that day measured between 37 and 50 feet high. They flooded the facility and destroyed the backup generators.

When the cooling systems failed, the temperatures in the reactor cores began to rise. The fuel rods inside the reactors started to overheat and melt, exposing the uranium fuel and damaging their containment vessels. At the same time, water in the reactors turned to steam and began reacting with the metal fuel rods, generating volatile hydrogen gas.

To relieve the pressure building up in the reactor cores, plant workers vented the gas several times over the next few days. This gas carried radioactive isotopes, also known as radionuclides, into the atmosphere, but this was not enough. Over following days, three hydrogen explosions at the plant sent even more radioactivity skyward, much of it eventually settling in the ocean.

Emergency crews desperately sprayed the overheating reactors with water cannons and firehoses, and military helicopters dropped hundreds of gallons of water from above. This water also picked up radionuclides and overflowed into the ocean or seeped into the ground, carrying those isotopes to the ocean.

Reactor Explosion

The earthquake knocked out power at Fukushima Dai-ichi and the tsunami flooded back-up generators, causing three of the six reactors to overheat and generating hydrogen gas that later exploded. Irradiated groundwater and cooling water flowed into the ocean, some collecting in beach sands and seafloor sediment, some building up in fish and other organisms, and the rest spreading with currents across the Pacific. (Fukushima Central Television)

Research expedition The first international research expedition in June 2011 traced the spread of radionuclides from the coast near Fukushima Dai-ichi to more than 300 miles offshore. Over the past decade, scientists, technicians, and members of the public have collected samples of water, sediment, and marine life from the ocean near the power plant to the West Coast of Canada and the U.S. (Photo by Ken Kostel, © Woods Hole Oceanographic Institution)

A radioactive ocean

Some of the most abundant radionuclides released in the disaster were iodine-131, cesium-134 and cesium-137. All are potentially hazardous, but they decay at different rates. Most of the iodine-131 was gone in a matter of weeks. With a two-year half-life, only 3% of the cesium-134 remains after 10 years, making it a telltale, but rapidly diminishing, fingerprint of Fukushima’s impact on the ocean. The cesium-137, which has a half-life of 30 years, will linger for decades. In fact, there is still a small but measurable amount of cesium-137 in oceans around the world from atmospheric nuclear weapons testing in the 1950s and ’60s.

“Since the dawn of the nuclear era, we’ve always have some cesium; the question is how much more did this accident add,” said Buesseler, who led a research trip to measure radiation near Fukushima in June 2011.  “We saw extremely high levels-more than 50 million Becquerels per cubic meter-of this radioactive form of cesium in the ocean close to Fukushima Dai-ichi.”

One Becquerel is a very small amount of radioactivity-it equates to one atomic nucleus decaying per second. The World Health Organization guidelines suggest that drinking water shouldn’t contain more than 10,000 Becquerels per cubic meter of cesium-137. Prior to the disaster, the waters around Fukushima had about 2 Becquerels per cubic meter. That shot up to over 50,000,000 immediately after the accident, then quickly dropped in the months following as measures to stanch the flow of radionuclides from the plant were put into the effect. Some of the radioactivity accumulated in the seafloor sediments, but much of it was dispersed into the Pacific by the strong Kuroshio Current, sparking fears that ocean currents would carry cesium to North America.

To investigate the movement of Fukushima radionuclides across the Pacific, Buesseler organized a community-based effort to determine what the levels of cesium were on the West Coast. His lab received seawater samples from ships operating in the area, and from surfers and beachgoers up and down the coast. While they did find evidence that some of the radioactivity from Fukushima had been carried across the Pacific to North America, the levels were extremely low-less than 10 Becquerels per cubic meter.

“That’s a very small number,” Buesseler said. “If you swam in the ocean every day for a year in waters that were about 10 Becquerels per cubic meter, the dose, the additional exposure, would be about a thousand times less than a single dental X-ray. The risk isn’t zero, but it’s so small that I wouldn’t be concerned about swimming, surfing or boating off the West Coast.”

The radioactivity at Fukushima has not entirely dispersed, however. Leaks from the reactors, radioactive sediment in rivers, and contaminated groundwater continue to flow into the ocean, albeit in much smaller amounts than in the first few years after the disaster. Levels in the coastal waters near Fukushima have stayed around 100 Becquerels per cubic meter since 2016.

Food chain

What about the fish?

The abrupt flood of radioactivity into the ocean was an immediate concern for local marine life, and a long-term concern for the people who consume it. The Japanese government immediately shut down fisheries and began an extensive monitoring and testing program to determine what seafood from the region, if any, would be safe to eat.

“Radionuclides that have been released into the ocean can be in either dissolved or particulate form,” said Sabine Charmasson, senior expert at the Institute for Radiological Protection and Nuclear Safety in France. “Both can be taken up by marine organisms.”

A fish living in a contaminated environment might absorb radionuclides through its skin or ingest them with its food or water, but how long they remain depends on the specific element. Cesium, for example, acts like its cousin on the periodic table, potassium, and is taken up by muscles and organs, where it can remain in the animal for weeks or months. Tritium, a radioactive form of hydrogen, behaves primarily like water and can be flushed out of an animal’s system in a matter of days. Strontium is more akin to calcium, Charmasson said, and can linger in a creature’s bones for years.

The particular animal species in question matters as well. An octopus will take up certain radionuclides differently than a sea urchin. A fish with a speedy metabolism might clear contamination more quickly.

Researchers found that animals living near the seafloor around Fukushima had higher levels of radioactivity, even as the contamination levels in the water began to fall.

“This is because these fish feed on prey living on or inside contaminated sediment,” Charmasson said.

After a few years, however, the vast majority of seafood caught off the Northeast Coast of Japan, including the fisheries off Fukushima, was below Japan’s strict radiation limit of 100 Becquerels per kilogram. (The U.S. limit is 1200 becquerels per kilogram.) Since 2015, out of thousands of fish that were tested, only two have exceeded that level.

NOAA Map In the wake of the accidents at Fukushima Dai-ichi the spread of misinformation inflamed public distrust of information from scientists and government officials. One commonly shared fallacy was a map, supposedly showing the spread of radiation immediately after the meltdowns at Fukushima Dai-ichi, but that was actually a model of tsunami waves crossing the Pacific after the earthquake. (Image courtesy of NOAA Pacific Marine Environmental Lab)

A crisis of trust

Despite being demonstrably safe, the seafood from the Fukushima region still carries a stigma of contamination. Caroline Kennedy, who served as the U.S. ambassador to Japan from 2013 to 2017, recalled traveling to the region repeatedly to show that it was safe to visit and eat the local foods.

“You meet these people who are fishing and trying to grow food but everybody is scared to buy their food or their fish, understandably so in many cases,” Kennedy said. “This whole episode is something that, as we piece apart, has many lessons for different areas of disaster response, as well as personal and collective responsibility and science.”

Mistrust of information about Fukushima built in the days and weeks after the disaster, when people were desperate for answers to what seemed like simple questions: Where was the radioactivity traveling on land and in the ocean? Who needed to evacuate? What food was safe?

But communication from the government was messy, delayed, unclear, and incomplete said Azby Brown, lead researcher for Safecast, an environmental monitoring group formed in response to Fukushima. The first official map showing radiation contamination in the Tokyo area wasn’t released until October 2011, seven months after the disaster. Rumors and disinformation spread faster and farther than any official communication, adding to the confusion.

“Trust is not a renewable resource,” Brown said. “Once you lose it, you may never get it back.”

Before the Fukushima disaster, the Japanese limit for radioactivity in fish was 500 Becquerels per kilogram, already stricter than the international standard. In April 2012, in an in an attempt to build public confidence in the safety of Fukushima seafood, the limit was lowered to 100 Becquerels per kilogram. But the lack of clear communication around this change created more confusion and anxiety for many people. Had they previously been eating seafood that was unsafe?

“If you don’t think about who it’s for, how they’re likely to react, how they’re going to find this information, then the information may miss the target,” Brown said. “We have to anticipate the potential failure points and how things can be misunderstood.”

Many people lost faith in official sources of information early on in the disaster and continued missteps, as well as misrepresentation of some information, have compounded the problem, creating a crisis of trust around Fukushima.

Tank Image One of the enduring legacies of events that began on March 11, 2011, is the more than 1,000 storage tanks on the grounds of the Fukushima Dai-ichi nuclear power plant holding contaminated wastewater that the Japanese government wants to empty into the ocean. Exactly what that water is contaminated with remains unclear. (Photo by Ken Buesseler, © Woods Hole Oceanographic Institution)

Fukushima’s ongoing legacy

In addition to changing the landscape of Tohoku, the disaster fundamentally changed the attitudes of of the Japanese people. In the aftermath, there was a renewed (some would say a new) sense of volunteerism and philanthropy in Japan. Atsuko Toko Fish, trustee of the Fish Family Foundation and co-founder of the Japanese Women’s Leadership Initiative, went to Tohoku just three weeks after the earthquake and tsunami to lend a hand and to distribute funds that she’d helped raise from her home in Boston. Japanese society has traditionally been resistant to outside help, whether it came from outside the country or even outside one’s family, so she knew that her help would only be accepted if the people trusted her. She spent months traveling back and forth between Boston and Tohoku, sometimes hitching rides on cargo trucks to get to the disaster-struck region-anything to prove that her motivations came from a sincere desire to help.

Her efforts, and those of many others, form the basis of something Fish calls “trust-based philanthropy.” In particular, she points to the role women have played in providing aid by focusing on building trust, which has had the added impact of giving new momentum to women’s rights in Japan.

“These women will shoulder the future of Tohoku,” said Fish. “They will be important future leaders of Japan, as well.” And their leadership will be needed, as there is still work to be done.

Today, the Fukushima Dai-ichi site is crowded with more than 1,000 towering storage tanks. They are filled with contaminated groundwater and cooling water that came into contact with the radioactive cores and debris. Currently, the wastewater is accumulating at a rate of more than 100 tons each day. The tanks were originally intended to be temporary, but they have become one of the more visible, and potentially long-lasting legacies of events that began ten years ago. The site will run out of space to store water by 2022, according to the Tokyo Electric Power Company (TEPCO), which owns the plant. The stored water has undergone a decontamination process, and the current plan is to slowly release it into the ocean.

But the decontamination process is not perfect, and a lack of transparency from TEPCO and the government has caused a public backlash against the plan, Brown said. TEPCO insisted for years that there was only tritium left in the tanks, a radioactive form of hydrogen that is difficult to remove but poses a lower health risk than other radionuclides. Only in October 2018 did the company finally admit that the water still contained additional contaminants.

These other radionuclides are more dangerous to human health, Buesseler said, and are more likely to remain on the seafloor and accumulate in marine life. “A little transparency would have gone a long way to make us accept and build a solution around not just tritium, but the other isotopes.”

The first step is to get a full accounting of what is in the tanks. Then, says Buesseler, TEPCO needs to demonstrate that they can remove the additional radionuclides, which they admit is needed for more than 70 percent of the tanks. Finally, independent monitoring of the ocean is needed to ensure that they only release what is permitted and at allowable rates. Buesseler also raised the possibility of building more tanks in the surrounding area-there is a 12-mile exclusion zone around the plant-to allow some of the shorter-lived contaminants to decay. But there are concerns that another large earthquake could fracture the tanks and cause uncontrolled leaks.

Whatever the solution, fully decommissioning and decontaminating the site will be a decades-long project. And as the marine ecosystem rebounds and communities in the area continue to rebuild, Buesseler knows the question of “is it safe?” will probably never go away.

“Even as levels get lower, the public will still have these questions,” Buesseler said. “And what I hope in ten years is that we’re still trying to give them answers.”

biology Coastal Ecosystems Ocean Life

Finding answers in the ocean

November 10, 2020

Finding answers in the ocean

In times of uncertainty, the deep sea provides potential solutions

By  | November 9, 2020

Deep-sea hydrothermal vents harbor diverse microbes whose enzymes can be used in diagnostic tests, like the ones to detect the novel coronavirus and other pandemics like AIDS and SARS. (Video acquired from the submersible Alvin at the East Pacific Rise near 9° 50’N at 2510 meters depth. © WHOI-NDSF, Alvin Group, National Science Foundation) vent Deep-sea hydrothermal vents harbor diverse microbes whose enzymes can be used in diagnostic tests, like the ones to detect the novel coronavirus and other pandemics like AIDS and SARS. (Video courtesy of Chris German, WHOI/NSF/ROV Jason/2012/© Woods Hole Oceanographic Institution)

The test being used to diagnose the novel coronavirus—and other pandemics like AIDS and SARS—was developed with the help of an enzyme isolated from a microbe found in marine hydrothermal vents as well as freshwater hot springs.

Biomedical breakthroughs sometimes happen in the most unlikely places. Take the deep ocean, for example, where mineral-laden fluid superheated by magma gushes from hydrothermal vents. Under extreme pressure and acidity, at times with no oxygen to speak of, microbes not only survive there, they thrive. This incredible adaptation offers insight into how life evolved billions of years ago—and how modern humans may be able to fight infections and disease.

“We’ve found marine microorganisms that produce antimicrobials—basically chemical weapons that help them fight off other organisms, and molecular mechanisms that help them resist viruses,” says Virginia (Ginny) Edgcomb, a WHOI microbiologist who investigates fungi and bacteria living in the deep sea and deep subsurface biosphere. These microbes feed on tough compounds like hydrocarbons and produce antimicrobial compounds. “Almost every antibiotic we have was produced by microorganisms. Who knows—maybe we’ll find new antimicrobials when we start to look in deep ocean habitats.”

The deep ocean has already given us compounds to treat cancer, inflammation, and nerve damage. But breakthroughs have also come from the ocean depths in the form of diagnostic tools. Case in point: the test being used to diagnose the novel coronavirus—and other pandemics like AIDS and SARS—was developed with the help of an enzyme isolated from a microbe found in marine hydrothermal vents as well as freshwater hot springs.

The pathway to developing this test started back in 1969 when scientists discovered a bacterium, Thermus aquaticus, living in the extreme temperatures of a hot spring in Yellowstone National Park. Two decades later, WHOI biologist Carl Wirsen and colleagues discovered new strains of bacteria on a hydrothermal vent off of Italy that could withstand even greater extremes (including heat, pressure, and lack of oxygen). More heat-loving microbes have since been found in hydrothermal vent communities across the globe to depths as great as 5000 meters beneath the sea surface.

By the mid-1980s, the unassuming microbes had enabled a major advance in the emerging field of genetics. Scientists found that their enzymes remained stable, even at the temperatures required to perform a revolutionary procedure known as polymerase chain reaction (PCR). With enzymes recovered from the microbes, it became possible to make millions of copies of a single DNA sequence in just a few hours, essentially upgrading geneticists’ tools from carbon-copy paper to state-of-the-art Xerox machinery. A technique using these enzymes, termed DNA polymerases, as well as enzymes isolated from viruses, now make it possible to quickly test for viruses, including coronaviruses like SARS (avian flu) and COVID-19.

Identifying microbial processes in the deep ocean is an essential first step for discerning human applications, says WHOI microbiologist Julie Huber.

“A lot of people think of the deep sea as a desert,” she says. “To our naked eye, it looks like there’s nothing there. But hydrothermal vents have a remarkable diversity of microbes, including genetic diversity. There’s huge potential there. What I can do as a basic science researcher is describe them and make their genome available. And folks in applied science can take that data and turn it into something useful.”

Edgcomb says the coronavirus outbreak underscores the importance of funding basic exploratory research, which may help lead to a cure or diagnostic tool in the future.

“You need to have people exploring different habitats in order to continue feeding the pipeline of medically-relevant enzymes (proteins),” she says. “This is a tough lesson to learn, with this pandemic, but I do hope people realize that the more we can learn more about microbes, the better off we are.”

biology Hydrothermal Vents Ocean Chemistry
Microplastics in the ocean

WHOI establishes new fund to accelerate microplastics innovation

October 26, 2020

WHOI establishes new fund to accelerate microplastics innovation

By | October 26, 2020 Microplastics in the ocean Confetti-sized bits of microplastic get swept through the ocean by fast-moving currents and shifting circulation patterns. (Photo by Shutterstock)

Despite regular media coverage and international concern over microplastics in the ocean, funding to study this emerging ocean pollutant has been surprisingly scarce. Early microplastics research by WHOI scientists was mostly funded through small grants that allowed them to explore very limited facets of the issue.

In 2017 and 2018, WHOI awarded Catalyst Funds—an incubator program funded by private donations—to form the Marine Microplastics Initiative. Leveraging WHOI’s interdisciplinary scientific staff, the initiative’s first priorities were taking stock of the existing research and coordinating a workshop to bring international experts together to chart a course forward. Now, the group has turned its attention to some of the most pressing—and foundational—questions about microplastics: How long do they last in the environment? Where do plastics discharged from wastewater systems end up? And what kinds of health risks do these plastics pose to animals and humans? They are also developing tools to sense and measure microplastics in the water and working on ambitious new projects related to the recovery and processing of plastic waste in the ocean. With the backing of a handful of family foundations, WHOI is launching a Marine Microplastics Innovation Accelerator to help drive innovation and support projects that will have the most impact.
Hannes Frey, a director at March Limited, says the company chose to fund WHOI’s microplastics research in order to help close knowledge gaps that stand in the way of a healthier ocean and to inspire others to make similar philanthropic investments. “As we talked to scientists, we realized that the breakdown into microplastics and their entry into the food chain is one of the most challenging issues to understand. It’s not as visible as animals trapped in fishnets or a seashore covered with plastic bags, but I think that on a scientific basis, it is crucial.” The Seaver Institute is another organization that is helping fund microplastics research at WHOI. “We give seed money for research and support projects that other people aren’t willing to fund until they become understandable,” says the foundation’s president, Victoria Dean. “We are interested in the discovery of scientific fundamentals and getting the information out there—WHOI does a great job of sharing their work.” Funding from private foundations has been an indispensable part of moving this research forward, says Mark Hahn, principal investigator of the Microplastics Initiative. “Currently, there are many more questions than answers about the fate and impacts of microplastics in the ocean,” he says. “The growing support from private foundations is critical in enabling the interdisciplinary, cutting-edge research that is needed to understand and solve this global problem.” Microplastic Research
WHOI geochemist Ken Buesseler discusses marine radioactivity monitoring in the Marshall Islands atop Runit Dome

Putting the ‘nuclear coffin’ in perspective

October 20, 2020

Putting the ‘nuclear coffin’ in perspective

Marine chemist weighs in on leaking radioactive dome in the Pacific

By Evan Lubofsky | August 13, 2019

WHOI geochemist Ken Buesseler discusses marine radioactivity monitoring in the Marshall Islands atop Runit Dome WHOI geochemist Ken Buesseler discusses marine radioactivity monitoring in the Marshall Islands atop Runit Dome—a 350-foot-wide concrete lid built to contain contaminated material from nuclear weapons tests. (Photo courtesy of Ken Buesseler, Woods Hole Oceanographic Institution)

There has been a flurry of headlines this summer about a “nuclear coffin” leaking radioactive waste into the Pacific Ocean. The coffin—a bomb crater filled with radioactive soil on a tiny island in the Marshall Islands—sits under a 350-foot-wide concrete lid known as Runit Dome. It’s arguably the region’s most visible scar from a series of U.S. nuclear weapons tests that took place off Bikini and Enewetak Atolls between 1946 and 1958.

The concerns aren’t unfounded—the area has been a hotspot for lingering radioactivity for more than half a century.  But according to Ken Buesseler, a world-renowned expert in marine radioactivity at Woods Hole Oceanographic Institution (WHOI), the concerns are nothing new.

“We’ve known for years that the dome is leaking,” he said. “When we were there doing fieldwork in 2015, we sampled groundwater and could see there was an exchange between the lagoon water and material under the dome. But it was clear that only a small amount of radioactivity was actually leaking into the lagoon.”

To put “a small amount of radioactivity” into perspective, Buesseler says the amount of plutonium under the dome is just one percent of the total amount buried in the surrounding lagoon sediments, which is less than 0.1% of the plutonium released during the weapons testing more than 60 years ago. These amounts fall below contamination levels for U.S. and international water-quality standards. More generally, radiation levels for the islands of Enewetak Atoll, according to a 2016 study from researchers at Columbia University, are even lower than those in New York City’s Central Park due to the high background radioactivity of granite rocks in the park.

“The dome is a significant visible scar on the landscape, but it’s a relatively small source of radioactivity,” said Buesseler, who had no hesitancy swimming in the azure waters off Runit Island during the 2015 field study.

However, he says the area is generally still of great concern and needs to be closely monitored. A more recent study from Columbia suggests that radiation levels vary significantly between islands, and higher levels have been measured on nearby Bikini and Rongelap atolls. Rongelap, in particular, had received considerable fallout from the 1954 Bravo test, resulting in subsequent decades of local contamination and radiation poisoning throughout the atoll.

Runit Dome sits roughly 25 feet above sea level on low-lying Runit Island, making it vulnerable to inundation from rising seas. People on top of the thick concrete cap, which measures nearly 400 feet in diameter, look like ants in this aerial view. (Photo from Wikimedia Commons)

Runit Dome, which is located on Runit Island—one of 40 islands that make up Enewetak Atoll—was built in 1977 as a temporary measure to contain some of the radioactive material left behind from the bomb explosions, some of which were one thousand times more powerful than those that destroyed Hiroshima and Nagasaki. The U.S. Army bulldozed more than 100,000 cubic yards of contaminated soil and debris into a bomb crater and capped it with hundreds of 18-inch-thick concrete slabs. From a Google Earth perspective, the massive dome looks like something out of science fiction, and completely out of place against the expanse of paradise around it.

While the dome has helped contain the waste and residual contamination levels on Enewetak, there’s no telling what the future holds.

“As long as the plutonium stays put under the dome, it won’t be a large new source of radiation to the Pacific Ocean,” he said. “But a lot depends on future sea-level rise and how things like storms and seasonal high tides affect the flow of water in and out of the dome. It’s a small source right now, but we need to monitor it more regularly to understand what’s happening, and get the data directly to the affected communities in the region.”

Runit Dome, which is located on Runit Island—one of 40 islands that make up Enewetak Atoll—was built in 1977. It was an attempt to contain some of the radioactive material left behind from nuclear testing during which more than 30 megatons of TNT was detonated. The U.S. Army troops bulldozed more than 100,000 cubic yards of contaminated soil and debris into a bomb crater and capped it with hundreds of 18-inch-thick concrete slabs. From a Google Earth perspective, the massive dome looks like something out of science fiction—and completely out of place against the expanse of paradise around it.

The military never returned to the islands to remove the waste—and it’s hard to say where they would have put it if they had. But it turns out, the dome may end up being a temporary container for the contamination after all: rising sea levels have caught up with it.

“The dome is only about 25 feet above sea level to begin with,” Buesseler said. “And sea levels are now at the point where seawater has been washing up on the dome and eroding its concrete edges.”

He says there has been some patching of the concrete, but it’s not a long-term solution. Increased seawater inundation over time will hasten the deterioration.

“They hadn’t considered sea level rise in the 1970s when they built this,” Buesseler said. “And at the current rate, the whole dome will be at least partially submerged by the end of this century.”

That begs the obvious question of what higher seas will mean for additional radiation flow into the Pacific. Buesseler says it’s impossible to predict, but ongoing monitoring of the situation will be critical.

“As long as the plutonium stays put under the dome, it won’t be a large new source of radiation to the Pacific Ocean,” he said. “But a lot depends on future sea-level rise and how things like storms and seasonal high tides affect the flow of water in and out of the dome. It’s a small source right now, but we need to monitor it more regularly to understand what’s happening, and get the data directly to the affected communities in the region so the people there have more confidence in what their levels of exposure are.”

MC&G Department Radiation Health Risks Café Thorium
A DISCO in the Ocean

A DISCO in the Ocean

January 30, 2019

How do you measure a chemical in the ocean that exists for less than a minute?

This was the conundrum facing Colleen Hansel, a scientist at the Woods Hole Oceanographic Institution (WHOI). She studies superoxide, a molecule so unstable that it reacts almost instantly with other molecules around it, vanishing in about 30 seconds.

Bringing water back to the lab simply didn’t work. Any superoxide in it would be gone long before the water could be tested. For years, scientists had measured superoxide in experiments using pumps and a benchtop instrument in the lab designed for the task. However, that device was not built to be used in the field. Superoxide had never been directly measured in the ocean.

Superoxide molecules are an accidental byproduct of breathing. They are ubiquitous and highly toxic. Any living organism that breathes oxygen creates them, and then needs to dispose of them quickly.

To create energy, cells extract electrons from fats and carbohydrates and transfer them to oxygen. When an oxygen molecule grabs four electrons, it then combines with hydrogen to form water.

But this process can be sloppy, particularly when organisms are stressed. Sometimes, oxygen only takes one electron. This makes superoxide. The extra, unpaired electron makes superoxide highly reactive. It either wants to lose or gain another electron to become more stable. To do that, superoxide gives or takes electrons from other cells, setting off destructive chain reactions.

Superoxide has been linked to harmful impacts ranging from cancer to premature aging in humans. Ocean scientists also suspect that superoxide might be involved in coral bleaching—the phenomenon that occurs when the symbiotic algae that live inside corals (giving them food and their vibrant colors) suddenly depart, leaving corals pale and vulnerable to starvation, disease, and ultimately death.

But a link between superoxide and coral bleaching has only been indirectly inferred from studies in the lab.

“It’s difficult to directly measure superoxide in the ocean,” Hansel said. “We were discouraged by the fact that we couldn’t make any measurements in the field.”

Expensive equipment in a very small boat

If Hansel couldn’t bring the samples to the lab, then she had to bring her lab to the samples.

“We said, ‘Let’s just take this lab benchtop instrument out onto a small zodiac on a local pond to see if we can make measurements and hope that we don’t tip the boat over,’” Hansel said.

In 2012, she and a postdoctoral scientist in her lab at WHOI brought their lab instrument out onto Oyster Pond, a large, brackish pond on Cape Cod. They knew bacteria in the water produced superoxide, but could they pump the water fast enough into the instrument on the boat to capture it before it reacted away? If the water pumped into the instrument too quickly, the sensor wouldn’t have enough time to make a measurement. If the water moved too slowly, the superoxide would be gone.

It was a complicated operation. They lowered a weighted tube into the water connected to a pump to draw samples up to the boat. As those waters fed into the sensor, a second pump pulled in a chemical from a separate bottle that specifically binds with superoxide. Once it was analyzed, the waste water was collected through a third tube, while the data was sent to a laptop via Bluetooth, where Hansel could see it in real time. The whole system was connected to portable lithium batteries—also balanced precariously in the zodiac.

And it worked. The setup was unwieldy, and if the tube went too deep, the superoxide would be gone before it made it to the instrument on the surface. But it worked: Hansel had proved it was possible to measure superoxide in situ outside the lab.

This presented an opportunity that Hansel and her WHOI colleague, Amy Apprill, had been waiting for. They now had a tool to measure superoxide around corals in the wild to explore its role in coral stress and bleaching. They finally got their chance in 2014 when widespread bleaching occurred in shallow corals in Hawaii.

Into the wild 

The fall of 2014 was a bad time for coral in Hawaii. The weather was unusually warm and prevailing winds, which usually pushed cooling open-ocean water toward shore and over coral reefs, died down. Coastal water temperatures in Kaneohe Bay, on the western side of Oahu, rose into the high 80s. More than three quarters of the dominant corals on the Kaneohe reef had bleached.

The theory behind coral bleaching is that superoxide builds up inside corals in response to heat stress and causes them to eject the algae they rely on. But as Hansel and Apprill loaded their setup into a small rented boat, they weren’t planning to measure the superoxide inside the corals. They wanted to know whether the corals were producing superoxide outside their cells in the surrounding waters.

They had seen this behavior in corals growing in aquaria in the lab. But were they doing it in the wild as well?

“I had concerns that the approach wasn’t going to work,” Hansel said. “Were the corals making enough superoxide for us to measure it using the set-up on the boat?”

But when the first measurements started coming in, from a resilient coral species known as Porites compressa, they showed that the corals had high levels of superoxide surrounding their colonies. Hansel couldn’t contain her excitement. 

Several more days of sampling began to reveal a pattern: Hardier coral species, the ones more likely to recover from coral bleaching or avoid infections, had more superoxide around their colonies. More fragile species had less, or none at all.

Clearly, there was more to the superoxide story. Perhaps superoxide could be beneficial to corals as well.

To see if these results were part of a larger pattern, Hansel would need to test other, deeper reefs. The reefs in Hawaii were shallow, allowing Hansel and her team to pump water to the instrument set-up in their boat before the superoxide vanished. She needed a better tool.

“After Hawaii, I knew that I wanted to make an in-situ instrument,” Hansel said.

DISCO designs

Back in Woods Hole, Hansel started brainstorming ideas with WHOI biogeochemist Scott Wankel. Wankel had experience building deep-sea sensing instruments for exploring hydrothermal vents on the seafloor. The two scientists have been married for 11 years.

“We sit around talking a lot, obviously,” said Wankel. “I remember sitting in the kitchen, taking a napkin, and drawing it. ‘What do you need? And how does it work? I have a pump that could do that …’ and putting this idea together.”

Together, over a year’s worth of Saturday morning coffees, they began to design what would become the DISCO: a portable, underwater, superoxide detector.

DISCO is short for DIver-operated Submersible Chemiluminescent sensOr (“We cheated on the acronym a little bit,” Wankel said.) It’s a device the size of a small suitcase, controlled by a handheld screen with five buttons and real-time read out display. It is a hefty 60 pounds in air, but neutrally buoyant in water and can operate to depths of 100 feet (30 meters).

The basic mechanics of the DISCO are similar to the lab instrument. Water is pulled inside through a long, thin wand and mixes with a chemical that reacts with superoxide in a mixing cell to produce light that is detected by a photomultiplier tube. The amount of light detected is translated through a small computer to show how much superoxide is in the water.

But this relatively straightforward reaction is made exponentially more complicated by superoxide’s tendency to react with any material it meets. “Superoxide is non-selective,” Hansel said. “It reacts with carbon, metals, other organisms. It reacts with nearly everything.”

The DISCO had to be built out of inert materials such as certain plastics, ceramics, or glass that superoxide can’t react with—nothing metal. These parts can be found, but they’re highly specialized and typically not made for underwater use.

Wankel reached out to WHOI engineer Jason Kapit, who he had worked with on several other projects. “Jason is a master of perusing the literature to find parts and pieces we can use,” Wankel said.

“You’re trying not to re-invent the wheel,” Kapit said. “Sometimes it takes cannibalizing a part that already exists and adapting it to what you want.”

Eventually he found parts from inert benchtop chemistry pumps to pull in seawater and intravenous bags from the medical industry to hold the necessary chemicals. These, along with a small computer, a lightproof chamber, and various other components were packed into a waterproof, pressure-bearing case.

Hansel had been invited to bring the DISCO on a joint U.S.-Cuban expedition to the Gardens of the Queen reefs in Cuba in October 2017. The expedition, led by Apprill, was aboard the research vessel Alucia. The group had hoped to finish the DISCO in time to test it locally, but design and construction took them longer than expected—into the fall of 2017.

“Right before we had to leave, we got it dunk-tested to confirm that it turned on underwater and didn’t leak,” Hansel said. “Cuba was the first field test.”

The trip to Cuba was an opportunity to see if coral species in a healthy Caribbean reef were producing superoxide like their stressed Hawaiian counterparts. That information could lead to a better understanding of the role of superoxide. But getting the data was entirely dependent on the unproven DISCO actually working.

A two-faced chemical?

Scott Wankel knew there were a lot of things that could go wrong.

“This was Colleen’s first project developing an instrument,” he said. “I kept warning her that the alpha prototype may never even make it to the water, let alone make a measurement, let alone make a measurement that is actually meaningful.”

Hansel wasn’t even going to be the one to first test the DISCO in the ocean. Her graduate student, Kalina Grabb, was joining the boat in Cuba two weeks before Hansel.

“It was nerve-wracking. We didn’t know what would happen,” Hansel said. “This was a lot of pressure for a first-year student, so I told her before she went, if you don’t feel comfortable, don’t do it. But she jumped in with it, and she got data on the first dive.”

It wasn’t entirely smooth sailing. The pumps ran too hot and caused the readout screen to overheat.

“After about 10 minutes of use under water, the screen would freeze,” Hansel said. “It took us a while to realize that DISCO was actually still collecting data, we just couldn’t see it.”

Flying blind, they collected data from a variety of coral species. When they were able to view it on the computers, it matched up with what they had previously seen in Hawaii and in the lab experiments.

“What we got from the DISCO is exactly what we got from the benchtop instrument that we schlepped onto the boat in Hawaii and the same that we got with the aquaria-based corals,” Hansel said. “Porites, a coral known for its resistance to stress, has extremely high concentrations of superoxide around itself, sometimes a hundred times higher than seawater.”

If the most resilient corals are producing the most superoxide, maybe superoxide isn’t all bad for corals. Perhaps the layer of superoxide on the outside of corals provides some kind of protection for stressed corals, like fending off viruses or bacteria that might otherwise infect them or helping with tissue repair. This would be similar to what scientists have observed in other forms of life, such as plants and fungi, and even mammalian cells.

“It’s exciting to think about,” Hansel said. “Is superoxide providing a physiological benefit to the coral?”

To answer this question, the team began working on a smaller, lighter version of the DISCO. Kapit took the lead on incorporating smaller, more efficient pumps to avoid overheating, a sleek touchscreen screen for the diver, and other improvements. He also eliminated machinery humming that emanated from the original DISCO, which attracted curious wildlife. Grabb field-tested the new DISCO in the Caribbean over six weeks in the summer of 2018.

The team is also working on a project called the SOLARIS (Submersible Oceanic Luminescent Analyzer of Reactive Intermediate Species), a superoxide detector that can be used at deeper depths and could be incorporated into a deep-sea sampling platform such as WHOI’s submersible, Alvin.

SOLARIS will allow the team to better understand superoxide’s role throughout the ocean. In addition to coral bleaching, superoxide has been implicated in harmful algal blooms and fish kills associated with red tides. But based on lab experiments, Hansel and colleagues have an emerging theory that superoxide is important, perhaps essential, for cell growth in bacteria and phytoplankton.

“Because superoxide is so reactive, it’s going to play a central role in nearly all biogeochemical cycles,” said Hansel. “Being able to finally measure superoxide directly within various marine ecosystems will transform our understanding of its role in ocean chemistry and health.”

This research was funded by Schmidt Marine Technology Partners and the National Science Foundation’s Division of Ocean Science.

Investigating Oil from the USS Arizona

Investigating Oil from the USS Arizona

December 7, 2018
Sweat the Small Stuff

Sweat the Small Stuff

December 3, 2018

An estimated eight million tons of plastics enter our oceans each year, yet only one percent can be seen floating at the surface. This is the first in a three-part article series about how researchers at Woods Hole Oceanographic Institution are trying to understand the fate of “hidden” microplastics and their impacts on marine life and human health.

When we think of plastic in the ocean, we often think of easily seen things such as water bottles and plastic bags. In reality, the vast majority of plastics in the ocean are smaller than a millimeter and can’t be seen with an unaided eye; some particles resemble bird seed, others look like dust.

These small fragments are known as microplastics. Some are “micro” by design: Microbeads, for example, are tiny plastic spheres manufacturers add to body washes, toothpastes and other products to give them extra scrubbing power. Lentil-sized pellets known as nurdles are ubiquitous fodder used in the manufacture of many common plastic products, are also intentionally small.

Other microplastics become “micro” over time when larger pieces of plastic debris, such as water bottles, straws, cups, and car fenders, are exposed to forces of nature that cause them to degrade. Sunlight, for example, oxidizes plastic and causes it to weather and degrade. Freeze-thaw cycles can weaken the structure of plastics over time. And ocean waves could also be taking a toll, making plastics more brittle by constantly washing over them and grinding them into sand.

Scientists have a decent sense for the types of physical and chemical weathering processes that can cause plastics to break down. However, little is known about how quickly degradation happens, and whether most of it is happening on land, in rivers, or in the ocean. It’s unclear, for example, what happens to a plastic water bottle between the time someone takes his or her last swig and when the empty bottle ends up in the ocean, said WHOI senior scientist Chris Reddy.

“There’s a perception that most of the fragmentation of plastics is happening in the ocean, but it could be that a lot of the activity is actually happening on land,” he said. “For example, if you take a red ‘Solo’ cup and leave it on the ground outside for a week, you can see that the red color starts to fade to pink and that the cup is more brittle. So, pre-aging on land could be playing a major, currently unaccounted for role in the fate of plastics in the ocean.”

Another big unknown is the impact marine microbes have on the breakdown of plastics in the ocean. Studies have demonstrated that microbes cling to even tiny plastic fragments, and nibble at them as well. But whether they are causing any significant breakdown of the material is something that scientists at WHOI are just starting to investigate.

The uncertainty surrounding where and how quickly plastics break down has become a critical knowledge gap not only for scientists, but also for chemical companies and plastic manufacturers that want to design plastics that decompose faster into materials that are non-harmful and have minimal effects on the environment.   

One way to gauge the speed of degradation is by placing plastics—including “raw” plastics containing no additives, as well as consumer products such as Styrofoam cups—in specialized weathering chambers. Scientists can conduct experiments in these chambers that test how factors such as sunlight, temperature, and humidity contribute to physical breakdown processes.

“These chambers provide a realistic picture of what happens on land and in the ocean,” Reddy said.

Collin Ward, a marine chemist at WHOI, says one of the main advantages of the weathering chamber is speed: It can accelerate the weathering process to answer environmentally relevant questions faster. When testing the effects of sunlight, for example, the chamber’s light source can be cranked up to flood plastics with ultraviolet light that is ten times more intense than natural sunlight.

“Some of the longest experiments I’ve ever run have been on plastics, and the reaction times are very slow since plastics are designed to not break down easily,” he said. “With these chambers, we can easily get the equivalent of a month’s worth of sunlight in one week, so it really accelerates the weathering.”

Weathering chambers will help, but Ward says that gaining a true sense for how plastics breakdown will be far more complex than simply blasting them with sunlight in a box. This is due to the fact that there are so many different types of plastics, and each type may break down at different rates in the environment due to the base polymers used and the types of additives and pigments applied to the materials during the manufacturing process.

“Cellulose acetate is completely different from polystyrene and polyethylene,” he said, “so these products will weather at different rates and by different processes. And then you have plastics that come in various colors, each with their own pigments and additives that can initiate the fragmentation process at different rates. When you consider all the variables that can impact the breakdown process, it becomes an incredibly complex science question.”

For more information about WHOI’s Marine Microplastics Initiative, visit

Journey to the Bottom of the Sea

October 4, 2018

My eyelids were tightly pressed down as I mustered all the tricks I could think of to get myself to sleep. I rolled around with no sign of getting close to slumber. I had no ticking bedside alarm clock to mark the passage of time. The only audible sound was the thunderous waves crashing against the side of the research vessel Atlantis.

Tonight was far from ordinary. Soon after sunrise, I would dive to the bottom of the Pacific Ocean in the submersible Alvin. I had learned about Alvin for the first time in a biological oceanography class I took in my sophomore year at Chulalongkorn University in Bangkok, Thailand. That seemed like a long time ago. Since then, I had become a graduate student in the MIT-WHOI Joint Program in Oceanography, and I had seen so many photos and videos of hot springs on the seafloor, spewing hot fluids like geysers into the deep ocean. But all of those were nothing compared with what I was about to witness with my own eyes.

My goal for this dive was to collect some samples of hot fluids venting from the seafloor 1.6 miles beneath the surface. I was looking for a particular chemical compound in the fluids: ammonia.

Many of you know ammonia as a common ingredient in cleaning products or fertilizers. But it is also scientifically intriguing, because it is the nitrogen-containing compound that can be converted most easily into key building blocks necessary for life: amino acids—the foundation for proteins and enzymes.

Ammonia is scarce in the ocean, but you can find it in large amounts at vents. Not only are vents oases of life in the deep sea today, they are also thought to be among the possible places where the first life forms on Earth emerged in the distant geologic past. My hope is to study the chemical fingerprints of the ammonia in vent fluids and unravel the chemical processes going on beneath the seafloor that produce it. If we can better understand the geochemical forces that produce ammonia today at vents, it will help open a window into what may have been happening in Earth’s ancient ocean to spark life.

Down to the abyss

Each Alvin dive requires an extraordinary amount of preparation. Many scientists studying various aspects of vents were aboard Atlantis, and Alvin was at the service of all of them. At a meeting the night before my dive, Stefan Sievert, a biologist at Woods Hole Oceanographic Institution and chief scientist of our expedition, went through the long list of tasks to accomplish during the dive. The pilot would execute those tasks, but it is imperative for the scientists inside Alvin to fully understand them, as they often have to make instantaneous judgment calls on how to proceed when questions and unanticipated circumstances arise—as they commonly do.

Now you probably understand why numerous thoughts were racing in my mind as I rehearsed every possible scenario that might happen on the dive and went through everything that needed to get done.

The next morning, full of adrenaline, I got into Alvin. The descent to the seafloor took a little more than an hour. The scene there was eerie; all around us were barren fresh lava rocks. Beyond the vents themselves, not much lives down there except for occasional weird-looking, eel-like fish.

The temperature reading at the seafloor was about 1.6° Celsius (35° Fahrenheit), barely above the freezing point. We started on our long list of scientific tasks to accomplish during the six to eight hours at the bottom.

Crab Spa was the first stop. This is the name of a lukewarm hot spring venting fluids with temperatures of about 25° C (77° F). It hosts numerous tubeworms, mussels, and, as you may have guessed, crabs, which, unlike their colorful shallow-dwelling counterparts, are all white. They spent most of their time around vent orifices that were spewing warm water out of the seafloor. The crabs were trying to grab pieces of white mats made of microbes and shove them into their tiny mouths. It was a pretty amusing scene to witness.

Vent-SID in action

After we took some fluid samples from Crab Spa vents, our next task was to deploy a newly developed instrument called the Vent-SID, short for Vent-Submersible Incubation Device. Sievert and his colleagues are studying the metabolic activities of microbes in vents. To date, scientists have conducted this research by collecting vent fluids, bringing them back on board the ship in incubation devices, and trying their best to simulate the pressure and temperature conditions found at vents.

Investigating these microbial activities through experiments conducted in situ is a better way of understanding what is actually happening in nature. But that’s a daunting challenge. Vent-SID is designed to be placed near vents and suck vent fluids into an incubator chamber. Inside, microbes in the vent fluids carry on their normal biochemical activities, which Vent-SID can measure. The key is that all these chemical reactions are carried out in situ, under the conditions in which they normally happen.

Finding a perfect spot to place the 3.5-by-2.5-by-8-foot-tall Vent-SID was not easy. Yet Pat Hickey, a veteran Alvin pilot with more than 680 dives, did not take long to use Alvin’s two manipulator arms and put Vent-SID right above a Crab Spa vent orifice. Then he maneuvered a temperature probe into the venting fluids to find the best place for the Vent-SID to take fluids into its incubator chamber.

Vent-SID would automatically start filling the chambers with vent fluids (along with the microbes in them) and begin its job as an in situ robotic lab, performing experiments scientists typically do either onboard the ship or back in a lab on land—including injecting chemical tracers, collecting microbes after incubation, and preserving samples for genetic materials. The experiments will help elucidate the kinds of microbes down there and the types and rates of biochemical reactions they perform—in an effort to understand the critical roles microbes play in sustaining vent ecosystems.

Chimneys on the seafloor

We had several more vent sites to visit on our dive. Our next stop was a spectacular site called Bio9. When we approached the area, the clear water was suddenly filled with what looked like dense black smoke. Then it was as if that velvety black curtain was pulled open, and we could see several enormous structures that looked like rocky chimneys spewing the black smoke. These tall structures form when the hot vent fluids meet cold seawater and almost instantly solidify. The “smoke” spewing out is actually vent fluid filled with minerals dissolved from subseafloor rocks. Some of the chimneys were extinct, and others were actively emitting very hot fluids.

Black-smoker chimneys form when the vents fluids are hot. Fluids emanating from Bio9 can be as hot as 360° C (680° F). The fluids and inner chimney walls are too hot for microbes, as life can tolerate temperatures up to only 122° C (252° F). But the fluids cool down quickly when they spew into seawater, creating a more hospitable environment for life to thrive.

Fluids from high-temperature vents such as Bio9 are also particularly important for my research, because they are too hot for living things, such as microbes. So any ammonia in them cannot have been produced by chemical reactions involving microbes. That is the type of ammonia that billions of years ago could have been converted into amino acids that led to the first life on Earth.

We proceeded to collect fluid samples from Bio9 with what we call Major samplers. We had a lot of samples from high-temperature vent sites. So we called it a successful day, dropped Alvin’s weights, and floated back to the surface.

A hard day’s night

My long day in the submersible was no excuse for not having a long night in the lab.

My colleagues and I worked as fast as we could in clockwork fashion to get the vent fluids out of the samplers and into appropriate bottles and then process and store them away either in the refrigerator or freezer.

These samples were particularly foul-smelling. Every time we cracked open the Major samplers to take out the vent fluids, the smell of sulfide permeated the room. It is the same rotten-egg smell you experience from muddy salt marshes. This sulfide, as well as the ammonia that I measure, provide the chemical energy that vent microbes use to live and grow.

But this repugnant smell strangely reminded me of the childhood summers I spent at my grandparents’ home. In their backyard stood a dense mangrove swamp reeking of the same sulfide smell. My life seemed to have come full circle.

My teammates and I carefully extracted fluids from the Major samplers, one by one. We measured the fluids’ pH and salinity—the first line of evidence to confirm the integrity of the samples we had collected.

Most low-temperature vent samples have a salinity similar to seawater. Their pH, a measure of how acidic they are, ranges between 5 and 6, like that of black coffee. On the other hand, high-temperature vent fluids from the black smokers in this area tend to be fresher and have a pH of 3 to 4, like that of vinegar used in cooking.

It’s the high-temperature fluids that I am after.

Isotopes as a fingerprinting tool

Work does not end at sea. Back in the lab at WHOI, we analyze our precious samples with an isotope ratio mass spectrometer (IRMS), hoping to reveal the unique chemical fingerprints hidden within compounds found in the vent fluids. These chemical fingerprints are isotopes—forms of chemical elements with different masses.

I study nitrogen isotopes—more precisely, the ratios between the heavier and scarcer nitrogen-15 to the lighter and more abundant nitrogen-14. Scientists have used these nitrogen isotope ratios for decades to study food webs, trace fertilizer pollution in watersheds, or study the many chemical reactions involving nitrogen that happen in the ocean.

With my Ph.D. advisor, WHOI biogeochemist Scott Wankel, I am investigating the nitrogen-isotope fingerprints to reveal what chemical processes are happening below the seafloor to give rise to ammonia in hydrothermal vent fluids.

I also worked with WHOI geochemist Jeff Seewald to set up closely controlled lab experiments to learn more about ammonia-producing processes. I conduct these reactions within a bag made of gold. Gold is malleable and can withstand high pressure and heat, and it does not react with the other chemicals. So it makes a fine container to put in our reactor at high temperatures and pressures similar to those at seafloor vents.

There are many chemical pathways that can produce ammonia. Which is the major one? What conditions of pressure, heat, rocks, geological features, or other factors favor this pathway versus another? What scenario is more likely to make ammonia? What’s going on at present that would let us infer what might have been happening in ancient oceans to spark the emergence of life?

Like any problem in science, understanding the origin of ammonia in vent fluids is not straightforward. We are just beginning to uncover the geochemical processes beneath the seafloor that produce ammonia. Analyses of fluids from vents in different oceans may show other scenarios beyond what we see at Bio9 and other sites in the Pacific.

The more I explore the subject, the more I find questions begging for answers. And just as during the sleepless hours before my Alvin dive, these scientific questions from time to time keep me awake at night.

This research was funded by the National Science Foundation. Net Charoenpong is supported by the NSF, the J. Seward Johnson Fund, and a Thailand Ministry of Science and Technology fellowship.

Marshes, Mosquitoes, and Sea Level Rise

Marshes, Mosquitoes, and Sea Level Rise

October 2, 2018

In the 1930s, the Cape Cod Mosquito Control Project dug approximately 1,500 miles of ditches across marshes on the Cape to drain their water and reduce the number of ponds where mosquitoes can breed. Woods Hole Oceanographic Institution biogeochemist Amanda Spivak is studying how this and other management decisions have changed the ability of coastal marshes to store carbon and protect against sea level rise.