San Francisco scientists testing water samples to find invisible microplastic particles

SAN FRANCISCO (KGO) -- For researchers Diana Lin and Kayli Paterson, taking water samples from San Francisco Bay means thinking small. The goal of their specially designed pumping system is to capture and identify tiny particles of microplastic invisible to the naked eye. And many times, smaller than samples collected for earlier studies at the San Francisco Estuary Institute, which helped identify the scope of microplastic pollution in the Bay.

"So, our previous work, we were looking at stuff in the millimeter size range that you could still see visually and, and you would look at them under a microscope, but you could still see them without a microscope. And now we're going back. We're realizing that there are even smaller microplastics. And we're going down into we're using even smaller sieves and looking at stuff that's like small, like thinner than, like human hair," Lin explains.

The most recent samples were taken as a part of a pilot project, conducted with support from BayQuest and Aquarium of the Bay. Researchers believe the tiny particles may originate from a variety of sources ranging from car tires to clothing fibers to plastic products. But a key question is their effect on marine life and potentially the broader food chain.

MORE: SF scientists build robotic storm samplers to track pollutants before they reach the Bay

"We really want to understand. What are the levels of microplastics in the water? This is what the fish and organisms are exposed to. And we want to better understand the impacts to them. But we also want to inform management actions," Lin adds.

To help understand the broader picture, the team hopes to eventually pair their study results with data from an ongoing monitoring program the institute helps manage across the Bay Area watershed. Earlier this year, we caught up with Kayli Paterson and her colleague, David Peterson, as they were deploying robotic water sampling units. Paterson believes that discovering the source of the microplastics and their path into the Bay is critical to identifying solutions.

"So we are seeing that a major pathway for these microplastics is storm water. And so we want to be looking at upstream management practices, because once they're out in the bay, there's not a lot we can do about reducing their numbers. When they're in the Bay. It really goes back to managing upstream and managing them at sources," says Paterson.

MORE: Stanford teams tracking the path of microplastics from source to sea

The team now plans to deploy the more sophisticated collection system in a broader study set to begin this fall. Perhaps developing better ways to identify manage a form of pollution that's becoming an invisible threat to San Francisco Bay.

"That's why we do a lot of studies, with urban storm water runoff as well as wastewater to do the detective work to understand what are the major sources, looking at individual particles and looking at their little, their characteristics. So this might have come from, like a plastic bag break down or this might have come from, like a plastic fork that's broken down into the environment and really trying to make those linkages," says Lin.

Researchers will be working with the California Ocean Protection Council, which is tasked with building a statewide microplastics monitoring program.