Small Particles, Big Problems?

By Rona Kobell | 12/30/22 | Chesapeake Quarterly

It is the things she can’t see that worry Ana Sosa the most. Sosa is a microbial ecologist, so tiny would describe most of what she examines. It is a large purview and includes bacteria, algae, and investigating how microorganisms interact in the environment and sometimes disrupt natural processes. Many of these microscopic organisms can contribute to creating low-oxygen zones and toxic blooms in the Chesapeake Bay. But for her, the most concerning “micro” of all for the continued health of the marine ecosystem are microplastics, the tiniest bits of human-produced, inorganic matter in the Bay and worldwide.

Sosa’s office at the Institute of Marine and Environmental Technology (IMET) is next to the Baltimore Harbor, where microplastics are abundant. There, she takes samples from the water, sequences the DNA of the microorganisms living in it, and determines how plastic may be interfering with their biological processes such as eating, reproducing, and cycling nutrients throughout the system.

“I’ve always been worried about plastics, and microplastics just seem like the biggest threat to the environment. And they’re everywhere,” Sosa said. “If you walk along the harbor and you see big plastic, there’s definitely also small plastic.”

Microplastics are what they sound like—tiny pieces of plastic shed from fabrics, or the remnants of larger objects and materials from our sustained use of everything from candy wrappers to plastic bags. They range from 5 mm to a nanoscale size, with a nanometer being one-billionth of a meter. Long recognized as a problem in the world’s oceans, they are an emerging threat to the Chesapeake Bay and its tributaries.

A 2014 study confirmed these waters are a large landing spot for the tiniest plastics. Lance Yonkos, an aquatic toxicology specialist at the University of Maryland, led a team that found microplastics in all but one of 60 samples in the study, which became a noted peer-reviewed publication on the issue in the estuary. The Patapsco River, which includes Baltimore’s harbor, had the most. A follow-up 2015 University of Toronto survey collected surface samples from 30 sites in the Chesapeake from Baltimore to the mouth of the Potomac River that included inorganic particles, organic matter, and larger trash pieces. Researchers found microplastics in every single sample, said Julie Lawson, the study’s principal investigator. Read More >>