Staff from the global chemical logistics company Fluechem, who traveled from the UK to supervise handling sodium hydroxide, check out the progress. Photo by Sarah Schumann.
Sarah Schumann
“So you’re going on an acid trip?” asked my captain, Dean Pesante, as we threw lines aboard the gillnetter F/V Oceana and prepared to head out of Point Judith Harbor into Rhode Island Sound to haul gear one late July morning.
Acid trip? It took me a moment, then I remembered: The afternoon before, I had looped him in on a group text as I tried to find a fill-in for August 13, when I hoped to join a team from Woods Hole Oceanographic Institute as a fishing industry observer for their “Locking Ocean Carbon in the Northeast Shelf and Slope” (LOC-NESS) research cruise.
“Actually, it’s an alkalinity trip,” I replied. “It may not expand my consciousness. But it could make a valuable contribution to the climate toolkit.”
The purpose of the “alkalinity trip” was to release 16,500 gallons of highly alkaline sodium hydroxide solution into surface waters of Wilkinson’s Basin in the Gulf of Maine, then activate scientific instruments – autonomous underwater gliders, aerial drones, all manner of sensors, and plankton sampling equipment – to understand physical, chemical, and biological effects of this release.
A project like this had never been attempted before, and its novelty has made it a headline issue in New England. Some community members were flummoxed by the prospect of scientists dumping caustic chemicals into our beloved ocean wilderness. The motives for this project, however, relate to the ocean chemical property at the center of my banter with Dean that morning: pH.
The world’s oceans have absorbed about 30 percent of the excess carbon dioxide (CO2) gas emitted by humans since the Industrial Revolution, and become more acidic in the process, negatively affecting calcifying organisms such as shellfish and zooplankton. Meanwhile, global warming caused by rising concentrations of CO2 and other gases is melting glaciers, strengthening storms, intensifying droughts and heatwaves.
Scientists think that by adding alkalinity to seawater – a practice known as Ocean Alkalinity Enhancement, or OAE – humans may be able to coax the ocean into removing and storing more carbon safely in the sea, by converting dissolved CO2 gas to a naturally occurring molecule called sodium bicarbonate. This marine carbon dioxide removal (mCDR) could have added benefit, restoring the pH of local seawater, boosting survival of shelled marine organisms and the food webs and fisheries that depend on them.
The WHOI team, led by Dr. Adam Subhas, aimed to go beyond theoretical analysis. They wanted to put these relationships to test in an at-sea trial designed to be small enough to avoid unexpected ecological harm but large enough to yield meaningful scientific information. They spent several years developing a research plan, assembling funding, securing an EPA permit, coordinating community information exchanges, chartering research vessels, and sourcing required chemicals from around the world, to answer these questions:
If we add alkalinity to ocean water, how measurable are the indicators of carbon removal? And what impacts will occur to the surrounding ecosystem and sea life?
Getting into position
On the evening of August 12, the Offshore Supply Vessel Peter M. Mahoney departed the shipyard in Quincy, Massachusetts to steam 70 nautical miles eastward to Wilkinson’s Basin in the Gulf of Maine.
Sharing my stateroom were three women: An EPA employee was present to ensure that the project met conditions of the permit issued under the Marine Protection, Research, and Sanctuaries Act; two protected species observers would monitor for marine mammals and halt the experiment temporarily if any North Atlantic right whales appeared within 500 yards. Also onboard were the crew employed by Goodwin Marine Services, three marine engineers from WHOI, and a team from the global chemical logistics company Fluechem who traveled from the UK to supervise handling sodium hydroxide.
At 8 am on the morning of the 13th, we jogged in place at the designated dispersal side (near 42°32’33”N, 69°31’15”W). Captain Justin Goodwin took his post at the helm, while WHOI’s lead engineer Tom Lanagan set up a table with his laptop, radio, and cellphone for communicating with the research vessel R/V Connecticut, which was arriving from Woods Hole with scientists and technical instruments.
On the back deck, WHOI engineers monitored flowmeters. The system set up two days before involved three flows: A finely calibrated pneumatic pump affixed to a manifold would move a 50-percent sodium hydroxide solution out of tanks through a network of 2-inch stainless tubes; a tote containing 20-percent rhodamine water tracer dye for visualizing the solution in the environment was equipped with an 110-volt pump and a clear one-inch garden hose; and a 100-horsepower diesel-powered pump would move seawater from the side of the vessel to the stern to enhance mixing the solution into ocean waters.
All three flows converged in a “snorkel” mounted on the transom, lowered to a depth of one to two meters below the waterline. At the end of the snorkel was an outflow nozzle, where the solution of saltwater, sodium hydroxide, and rhodamine tracer dye would be injected into the surface of the Gulf of Maine.
Painting the ocean red
At 9 am, 16,500 gallons of red-dyed sodium hydroxide was dispersed creating a patch 800 meters in diameter over the next few hours.
The R/V Connecticut trailed 200 meters behind, picking up information about the surface water’s pH and fluorescence (an indicator of the concentration of rhodamine tracer dye). On the Mahoney’s bridge, a live-stream of measurements appeared on engineer Tom’s laptop, enabling him to spot any increases in pH levels above the EPA-approved thresholds of 8.7 or 10 parts per million; if exceeded, each would trigger a corrective action.
About four hours in, livestream data on Tom’s computer showed a small spike in pH, exceeding the 8.7 pH threshold by a hair. After consulting with the team on the R/V Connecticut, Tom instructed the crew to dial down the flow rate by 50 percent. This would extend the dispersal activity by a few hours, but still well within the 12-hour maximum allowed by the EPA.
A blue shark zigzagged back and forth beneath the boat. Soon after, an ocean sunfish flopped and basked in the patch.
Every now and then we’d pass a drifter buoy. These buoys have underwater sails that keep them pinned to the mass of water they are dropped in, even as currents move. Equipped with GPS beacons, the drifters’ role is to make it possible for the team to track the patch’s location even after the rhodamine tracer dye had ceased to be visible.
Mission accomplished
At 3 pm the trial was complete. The Mahoney’s job was done, and we returned to Quincy that night. But the R/V Connecticut stayed with the patch for four more days, and WHOI’s autonomous underwater gliders remained adrift in the area for another week.
It will take many months for the WHOI team to analyze all of the data, but lead researcher Adam Subhas reports that the treated patch of water returned to normal pH levels between four and five days after the sodium hydroxide release, no protected species had been spotted during the dispersal, and “our shipboard data is confirming the initial hypothesis of no significant environmental impacts.”
He added that early data shows the trial successfully and safely enhanced alkalinity of the surface, resulting in a small increase in pH and driving carbon dioxide from the atmosphere into the seawater patch. They’ll be sharing more results as the analysis proceeds.
If this work expands, fishermen will undoubtedly find ourselves on the front lines of any and all impacts that may result. Designating a fishing industry observer to witness each mCDR field trial and share notes, as I was able to do, remains crucially important.
This story was edited for length, read the whole story here https://www.fisheryfriendlyclimateaction.org/blog/a-fisherman-bears-witness-to-whois-alkalinity-experiment-in-the-gulf-of-maine.