New Study Reveals How Tiny Particles Sink Faster in Ocean Depths

In a groundbreaking study conducted by researchers from Brown University and the University of North Carolina at Chapel Hill, scientists have uncovered new insights into the behavior of organic particles in oceanic conditions. Published in the Proceedings of the National Academy of Sciences on June 22, 2025, the research indicates that smaller particles may sink faster than larger ones in stratified ocean waters, challenging previous assumptions in oceanographic studies.

The deep ocean often resembles a snow globe, filled with organic matter that descends from the surface, forming what is known as 'marine snow.' This phenomenon plays a crucial role in the cycling of carbon and nutrients throughout the world's oceans. The study led by Robert Hunt, a postdoctoral researcher at Brown University's School of Engineering, reveals that the speed at which these particles sink is influenced not just by fluid resistance but also by their salt absorption capacity relative to their size.

"It basically means that smaller particles can sink faster than bigger ones," Hunt stated, emphasizing the unexpected nature of this finding. The research highlights a significant deviation from the traditional understanding that larger particles would naturally sink more quickly due to their weight.

Daniel Harris, an associate professor of engineering at Brown and co-author of the study, described the development of a straightforward formula that allows for predictions of sinking speeds based on particle size and liquid density changes. "There's value in having predictive power that's readily accessible," Harris remarked. This new formula could have implications for understanding the ocean nutrient cycle and addressing issues related to microplastics.

The study emerged from earlier work focused on neutrally buoyant particles, which should theoretically remain at a constant depth. Hunt observed unexpected sinking behavior that led to the exploration of how particle porosity and salt absorption impacted sinking rates. The research team engineered a controlled environment simulating stratified fluids using pumps to mix fresh and saltwater, allowing them to manipulate the density of the liquid.

The experiments confirmed that smaller, spherical particles sink faster than their larger counterparts, while elongated particles demonstrated even faster sinking speeds than spherical ones of equivalent volume. These findings could provide critical insights into natural carbon cycling and methods for enhancing carbon capture in aquatic environments.

Hunt and Harris expressed a desire to connect with oceanographers and climate scientists to further explore the broader implications of their findings. The research received funding from the National Science Foundation and the Office of Naval Research, underscoring its relevance in both academic and practical applications.

As global concerns over climate change and ocean health intensify, understanding the dynamics of particle behavior in the ocean could lead to more effective strategies for climate mitigation and environmental protection. The implications of this research extend beyond theoretical physics and into practical applications in environmental science, marine biology, and climate studies, suggesting a need for increased collaboration between scientists across various disciplines.

### Conclusion The findings from this study prompt a reevaluation of established theories regarding particle behavior in oceanic environments. As researchers continue to explore the complexities of marine ecosystems, insights gained from this research may prove invaluable in addressing the challenges posed by climate change and pollution in our oceans. The study not only enhances our understanding of ocean dynamics but also lays the groundwork for future research aimed at improving carbon capture methodologies and mitigating the effects of microplastics in marine environments.