Brittany McIntyre arrived at the farm in Rio Claro, Trinidad, just before noon on a warm December day, walking into its lush, green fields to harvest peppers, cassavas, and other vegetables.
It was one of seven farms scattered across the dual-island Caribbean nation of Trinidad and Tobago she visited that month, gathering enough fruits and vegetables that could feed a family of seven for a week.
But the crops she collected would never be consumed.
The University of Miami Ph.D. student brought them back to a lab at the College of Engineering, where she tested them for levels of arsenic and other heavy metals.
The culprit? Sargassum seaweed.
Some farmers in Trinidad and Tobago have reimagined the smelly, yellowish-brown macroalgae that fouls the shores of their country’s beaches, converting it to compost to improve soil fertility and crop yields.
“It has shown promising results in that regard,” said McIntyre, who is on an environmental science and policy track through the Rosenstiel School of Marine, Atmospheric, and Earth Science but works out of the lab of College of Engineering researcher Helena Solo-Gabriele.
“But despite its potential agricultural benefits, the presence of heavy metals, particularly arsenic, in sargassum raises serious health and environmental concerns,” she said. “Sargassum has been found to bioaccumulate arsenic from marine environments, with variations in concentration influenced by natural oceanic processes and anthropogenic pollution. So, using it as a fertilizer introduces the possibility of arsenic transfer to crops, and that threatens food safety and human health.”
McIntyre’s research, funded by the Hinkley Center for Solid and Hazardous Waste Management in Gainesville, Florida, and the Boston-based Conservation, Food, and Health Foundation, will not only measure levels of arsenic concentrations in crops but also assess the risks of potential human exposure and explore ways to remove arsenic from sargassum.
“We’re employing a multidisciplinary approach that integrates environmental science, toxicology, and agricultural research to inform policies and best practices for the sustainable and safe use of sargassum,” she said.
McIntyre hopes to collect and test crops from farmlands in the Bahamas and Barbados, where some growers also use sargassum gathered from the coastlines of local beaches to fertilize their fields. Her study results, she said, will have far-reaching impacts, benefiting coastal communities around the world.
It comes as large amounts of sargassum seaweed continue to wash ashore and decay on coastlines of the United States, Caribbean, and Central America during certain times of the year, emitting hydrogen sulfide fumes that can kill fish, coral, and seagrass and cause headaches and nausea in beachgoers.
“This isn’t just a regional issue,” McIntyre said. “We’re seeing extremely large sargassum strandings happening all the way in New Zealand. And the heavy metals present in the seaweed are a concern, especially for underserved communities that might not have access to testing.”
Her visits to local farms in Trinidad and Tobago were a homecoming of sorts. She was born and raised in the borough of D’Abadie, Trinidad, experiencing some of the environmental challenges that sometimes impacted her homeland—from a massive oil spill to water scarcity.
“I remember after the oil spill how it wasn’t safe to eat fish from local waters, and other times when we’d turn on the tap, but no water would come out,” McIntyre said. “In many ways, those experiences greatly influenced my desire to study environmental science. My current research really hits close to home.”
