WHOI Successfully Completes Small-Scale Ocean Alkalinity Enhancement Research Trial in the Gulf of Maine

EPA-approved research proceeded in line with extensive modeling, with full results to come

Woods Hole, Mass. (August 25, 2025) – The Woods Hole Oceanographic Institution (WHOI) has successfully completed its EPA-approved, small-scale environmental research trial of ocean alkalinity enhancement (OAE) in the Gulf of Maine as part of the LOC-NESS Project. OAE is noted by leading scientific bodies like the National Academies of Science as a high-potential environmental solution, and is based on enhancing the ocean’s natural ability to remove large amounts of carbon dioxide from the atmosphere.

Background on the research trial:

• In April of this year, the Environmental Protection Agency (EPA) approved the LOC-NESS field research proposal following a rigorous, year-long review that included two public comment periods totaling 75 days and garnered more than 250 comments. The research earned significant, independent support from the scientific community.
• EPA consultations with NOAA Fisheries and the U.S. Fish and Wildlife Service found minimal potential environmental impact for the scale and nature of the proposed trial. The EPA determined that the project “demonstrates scientific rigor” and is “not expected to significantly affect human health, the marine environment or other uses of the ocean.”
• This non-profit research builds on years of laboratory experiments, computer modeling, and theoretical studies about the safety and effectiveness of OAE, and it comes as commercial ventures related to OAE are progressing.
• A series of lab experiments were conducted earlier this year with the copepod Calanus finmarchicus, with preliminary results showing no impact of elevated pH on this key food web species in the region.
• The LOC-NESS team performed a simulated alkalinity deployment at a 10-million-liter open-air federal testing facility in New Jersey, which helped refine the engineering and methodological design of the Gulf of Maine experiment.
• LOC-NESS team members organized or participated in more than 50 community engagement and outreach activities throughout the research design and public review process.

Key details about how the research trial was conducted:

• The LOC-NESS research trial was conducted August 13-17 in federally controlled waters approximately 50 miles off the coast of Massachusetts.
• WHOI scientists gradually added alkalinity to the water. They released highly purified sodium hydroxide—commonly used to adjust the pH of drinking water—into the surface ocean with an inert, red tracer dye known as Rhodamine Water Tracer (RWT) over the course of 6 hours.
• After releasing the alkalinity on August 13, WHOI scientists in a fully-equipped research vessel followed the patch of alkalinity through August 17, monitoring the physical, chemical, and biological conditions of the ocean to assess OAE’s potential for safely removing carbon dioxide from the atmosphere.
• In addition to the scientists on the research vessel, a group of 4 self-propelled autonomous underwater vehicles and free-swimming gliders were used to measure key water properties before, during, and after the alkalinity dispersal.

Key, initial takeaways from the research trial include:

• Extensive pre-trial research and modeling indicated that, as a result of the alkalinity addition, the brief pH increase would dilute to 9.0 within seconds and return to typical ocean conditions (pH 7.9-8.1) within days. Initial observations indicate that initial pH levels were consistent with these models, with a pH at the end of the dispersal of approximately 8.3. As models predicted, the pH values returned to baseline values (about 7.95) by the end of the 4-day monitoring period, which was accurately forecasted by models beforehand.
• Protected species observers reported that no protected species were observed within the area of activity during the trial.
• The research vessel R/V Connecticut, one of multiple vessels involved in the trial, was staffed by a team of nine scientists and technicians.
• The dispersal was witnessed by observers from the Massachusetts Division of Marine Fisheries (MADMF), the U.S. Environmental Protection Agency (EPA), National Oceanic and Atmospheric Administration (NOAA), and the fishing industry.

Next steps:

• Initial data appears to confirm that tracking OAE with a water tracer dye is a highly effective monitoring approach at the research stage, and that the experiment successfully and safely produced conditions that would allow for the surface ocean to take up carbon from the atmosphere.
• In the weeks and months to come, the research team plans to analyze collected samples, synthesize datasets, and generate results to be disseminated at scientific meetings and to the public and interested communities.

“We are excited that our small-scale research trial was completed in line with our extensive preparation and modeling, as well as the rigorous oversight required by the EPA,” said Adam Subhas, Associate Scientist in Marine Chemistry and Geochemistry at WHOI, and Project Lead of LOC-NESS. “We conducted this research hoping that it would help evaluate the effectiveness and environmental impact of OAE, and though we have a lot of analysis to do, we are confident that we’ll have rigorous results that advance scientific knowledge of OAE’s environmental impact. We need independent, transparent research to determine which solutions work, and we are eager to contribute to the body of evidence. We are very grateful to the EPA for their extensive review and careful consideration of our permit application, and we will continue to be in close contact with them as we analyze the findings from this research trial.”

“The LOC-NESS project stands out as the only mCDR field research initiative in the United States that proposes to operate independently of industry,” added Dr. Kristin Kleisner, Associate Vice President, Oceans Science at the Environmental Defense Fund. “This unique position makes it a critical scientific effort to complement the commercial pilot projects currently underway.”

This research, which has been supported by several philanthropic and federal funding sources, advances critical goals laid out in the National Marine Carbon Dioxide Removal Strategy released by the federal government in 2024, as well as a call by the National Academies of Science, Engineering, and Medicine for research to evaluate the safety and effectiveness of a suite of proposed ocean-based carbon dioxide removal techniques.

 

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About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu.

FOR BACKGROUND:

The EPA’s final permit material included several determinations about the rigor of the project and potential environmental impact, including:

• “Based upon its assessment, the EPA determined that the local, temporary changes in water chemistry associated with the research activities are not expected to significantly affect human health, the marine environment or other uses of the ocean.” (EPA Response to Comments, Page 4)
• “We concur with your conclusion that the proposed action is not likely to adversely affect any NMFS ESA-listed species or designated critical habitat.” (NOAA Fisheries Endangered Species Act Consultation, Page 2)
• “[T]he EPA determines that the Wilkinson Basin Study demonstrates scientific rigor and a strong basis (and need) for conducting the research study in ocean waters rather than in a laboratory or mesocosm.” (EPA Response to Comments, Page 11)
• “The research study was designed to minimize potential adverse environmental impacts while ensuring the permittee’s research goals could be achieved. The environmental monitoring plan for the LOC-NESS Wilkinson Basin Study would include robust monitoring of impacts to water chemistry and biological communities.” (EPA Fact Sheet, Page 22)
• The EPA determined that “seawater pH would be expected to be below pH 9 within 12 seconds” of the alkalinity release. (EPA Fact Sheet, Page 20) Drinking water is widely available with a pH higher than 9.