Meet Alaina Zhang, the 17-year-old Rhode Island student testing whether native seaweed can help clean polluted coastal waters

For Alaina Zhang, seaweed is more than something that washes up along the shore. It could be part of an answer to a pollution problem threatening coastal ecosystems.

The 17-year-old Rhode Island student created Harvesting Change, a project exploring whether locally grown seaweed can remove excess nitrogen from coastal waters before that pollution contributes to damaging algal blooms. Her research focuses on sugar kelp, Saccharina latissima, and suggests that farming the native seaweed could offer an environmentally friendly and comparatively inexpensive way to capture nutrients already in the water. Zhang's work earned her recognition as one of the 2025 winners of the Gloria Barron Prize for Young Heroes.

But the idea did not begin simply as a school science project. Zhang had seen the problem long before she began experimenting with kelp.

Algae-filled waters gave Zhang an idea

Zhang spent part of her childhood in China, where she saw waters affected by algae pollution. After encountering similar environmental problems along Rhode Island's coastline, she began investigating whether something already adapted to the marine environment could help.

She eventually turned her attention to sugar kelp. Working with researchers, field technicians and local fishermen, Zhang developed her project and raised nearly $7,000 to establish a student-run sugar kelp farm. She also contacted researchers at Brown University and the University of Rhode Island and secured permits from Rhode Island's Coastal Resources Management Council for the work.

Her central question was surprisingly straightforward: Could growing seaweed help take unwanted nutrients back out of the water?

Why too much nitrogen can become a coastal problem

Nitrogen itself is not the enemy. It is an essential nutrient that plants and algae need to grow.

Problems can emerge, however, when too much nitrogen enters coastal ecosystems from sources including wastewater and runoff. That nutrient surplus can encourage excessive algal growth. When large amounts of algae eventually die and decompose, the process can consume dissolved oxygen, creating conditions that make survival more difficult for fish and other marine organisms.

This process is part of what scientists call eutrophication.

Zhang began investigating whether kelp could work as a biological filter. Seaweed requires nutrients such as nitrogen to build its tissues. Grow the kelp in nutrient-rich water, the reasoning goes, and some of that nitrogen becomes incorporated into the seaweed's biomass. Harvest the kelp, and that captured material can potentially be physically removed from the ecosystem.

Her sugar kelp model produced a striking result

Zhang established a custom kelp farm in Portsmouth, Rhode Island, and collected field data from February through April 2024.

Her research analyzed nitrogen and carbon content in monthly kelp samples using dynamic flash combustion, based on the Dumas method. Those measurements were then incorporated into a one-dimensional box model to estimate what could happen at a larger scale.

The modeled results were striking. For a 2.5-acre, or roughly 1-hectare, kelp farm, Zhang's model estimated a 43.2% nitrogen removal rate and a 0.8% carbon removal rate. The project summary also estimated operational costs 99.3% lower than the comparison treatment approach used in the analysis.

Those numbers do not mean that kelp has already removed 43.2% of nitrogen pollution from Narragansett Bay. They are results from Zhang's modeled farm scenario and would require broader real-world testing before being applied to an entire coastal ecosystem. Still, they gave the teenager evidence that the idea was worth pursuing.

A school kelp farm grew into serious environmental research

Zhang's work quickly moved beyond an ordinary classroom experiment.

In 2024, Rhode Island's Coastal Resources Management Council awarded her first place in its senior-division special awards category at the Rhode Island Science and Engineering Fair for research examining sugar kelp as a sustainable and economical biofilter for wastewater treatment.

She was also Rhode Island's 2024 state winner for the Stockholm Junior Water Prize. The following year, she returned to the state science fair with research examining biogeochemical climate solutions in the Narragansett Bay estuarine ecosystem and again received first place from the Coastal Resources Management Council.

Her school reported that the 2025 project also received recognition from organizations including NOAA and the U.S. Air Force.

Zhang has since presented her work beyond Rhode Island. A profile from the National Society of High School Scholars says she presented research at the American Geophysical Union Annual Meeting and is lead author on two projects involving sugar kelp, nutrient removal and coastal resilience.

Her work didn't stop at the water's edge

Zhang has also taken the research into public policy and community outreach.

According to Rhode Island Monthly, she has shared her work with more than 500 Rhode Islanders through workshops and presentations. She has co-led the Narragansett Bay Resilience Collaborative, helped develop a policy brief on strengthening the bay's resilience and testified in support of environmental legislation.

That combination, laboratory measurements, fieldwork and policy, is part of what makes her project unusual for someone still in high school.


The Gloria Barron Prize ultimately recognized Zhang in 2025 for creating Harvesting Change and investigating native seaweed as a way to address nitrogen pollution along Rhode Island's coast.

Seaweed alone is unlikely to solve every source of coastal nutrient pollution. Preventing excessive nitrogen from reaching waterways in the first place remains important. Zhang's research instead asks whether kelp could become another tool available to coastal communities.

For a project that began with a teenager looking at polluted water and wondering what could grow inside it, that is already a significant question.

FAQs

How can seaweed remove nitrogen from water?

Seaweed needs nitrogen and other nutrients for growth. As kelp grows, it incorporates nutrients from surrounding water into its biomass. Harvesting that biomass provides a potential way of physically removing some of those captured nutrients from the marine environment.

How much nitrogen did Alaina Zhang's kelp project remove?

Zhang's research summary reported that a model simulating a 2.5-acre, or 1-hectare, kelp farm produced an estimated nitrogen removal rate of 43.2%. That is a modeled result and should not be interpreted as evidence that 43.2% of Rhode Island's overall coastal nitrogen pollution has already been removed.